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  • 2000-2004  (142)
  • 1995-1999  (3,023)
  • Analytical Chemistry and Spectroscopy  (2,388)
  • Human  (776)
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  • 1
    Electronic Resource
    Electronic Resource
    The transient disappearance of cytokeratin in human fetal and adult ovaries (2000)
    Springer
    Anatomy and embryology 201 (2000), S. 207-215 
    Details
    ISSN: 1432-0568
    Keywords: Keywords Granulosa cells ; Ontogeny ; Ovary ; Rete ovarii ; Cytokeratin ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Cells from the inner and outer granulosa cell layers of the ovarian follicles differ in function, probably because of their different origins from the surface epithelium and from the rete. This suggestion has not so far been thoroughly investigated in the human ovary. We examined fetal ovaries from the early, middle and late gestational periods, ovaries from fertile women, and preovulatory follicular cells obtained from patients under in vitro fertilization therapy (IVF). Indirect immunohistology and immunocytology were used to detect the presence of cytokeratin (CK)-positive epithelial cells. In fetal ovaries from the early gestational period, prominent rete tubules (sometimes with oocytes) appeared to be fused with the sex cords and primordial follicles. Both showed CK-positively, detected with the pan-CK antibody Lu-5. Cytokeratin 19 was clearly expressed in the fusion area. In the fetal and adult ovaries, CK-positive follicular or granulosa cells were noted in the primordial and primary follicles as well as the preovulatory follicles. Cytokeratin was not detected in the granulosa cells of growing follicles, CK-positive and -negative luteal cells were identified in the developing corpus luteum. We conclude for the human ovary: (1) the heterogeneous morphology of granulosa cells may be explained by their twofold origin from the surface epithelium and the rete, (2) the rete tubules appear to be involved in folliculogenesis, (3) the transient absence of CK expression in growing follicles compared to resting and mature follicles or to the developing corpus luteum indicates a particular role of CK-positive cells at the periovulatory period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050019
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  • 2
    Electronic Resource
    Electronic Resource
    Differential regulation of the monocytic calcium-binding peptides macrophage-inhibiting factor related protein-8 (MRP8/S100A8) and allograft inflammatory factor-1 (AIF-1) following human traumatic brain injury (2000)
    Springer
    Acta neuropathologica 100 (2000), S. 627-634 
    Details
    ISSN: 1432-0533
    Keywords: Key words Allograft-inflammatory factor-1 ; Microglia response factor-1 ; Macrophage-inhibiting factor ; related-protein-8/S100A8 ; Traumatic brain injury ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Intracellular calcium (Ca2+) has been shown to function as second messenger and to be associated with activation of different cell types including microglia. Previously, in human focal cerebral infarctions an early expression of macrophage-related protein-8 (MRP8/ S100A8), a member of the Ca2+-binding S100-protein family, in microglia has been reported. On the other hand, a delayed activation of microglia was observed following traumatic brain injury (TBI). We therefore examined immunohistochemically microglial expression of MRP8 and allograft inflammatory factor-1 (AIF-1), identical to microglial response factor-1 (mrf-1) and ionized calcium binding adaptor molecule-1 (iba1) in human brains after TBI and in control brains. Both, MRP8 and AIF-1 are Ca2+-binding peptides which have been associated with microglial activation in experimental models and in human cerebral infarctions. Detection of AIF-1 in controls confirmed constitutive expression of this peptide in a subset of microglial cells. After TBI, the density of AIF-1+ microglia did not increase significantly. Lesional expression of AIF-1 did not significantly differ from other brain regions. Furthermore, following TBI, we found no significant differences in the density of AIF-1+ microglia as compared to controls. Microglial MRP8 expression was not detectable in controls and within the first 3 days post TBI, but increased rapidly after 3 days post TBI, suggesting a subpopulation of microglial cells to be AIF-1–/MRP8+. We conclude that the delayed expression of MRP8 and the lack of AIF-1 up-regulation in microglia after TBI is in contrast to ischemic brain lesions and might reflect different activation cascades of microglia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004010000232
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  • 3
    Electronic Resource
    Electronic Resource
    Motor neurones in culture as a model to study ALS (2000)
    Springer
    Journal of neurology 247 (2000), S. I28 
    Details
    ISSN: 1432-1459
    Keywords: Key words Motor neurone ; Astrocyte ; Human ; Tissue culture ; ALS ; Glutamate ; Calcium ; SOD-1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Defining the basis of the selective cell vulnerability of motor neurones (MN) represents the key issue in amyotrophic lateral sclerosis (ALS), and tissue culture models are the ideal system for the identification of the MN specific features at the single cell level. Neurone-astrocyte metabolic interactions, which have a critical role in MN through glutamatergic toxicity, have been mostly defined in vitro. Ca++ metabolism, which appears to play a critical role in inducing MN loss in ALS, has been successfully studied using in vitro cell models. Furthermore, primary cultures demonstrated that apoptotic or necrotic death of neurones after injury depends upon the cell energetic status. Superoxide dismutase-1 (SOD-1) mutations were successfully expressed in cultured rodent MNs, providing a critical assay to sequence the molecular processes responsible for MN degeneration due to the identified genetic defect. The recent identification of genes that separate humans from apes further increases the value of the human in vitro models to better understand specific human cellular properties. Purified human MNs and astrocytes can today be obtained from the human embryonic spinal cord anterior horns. Interactions at the single cell level can be dissected using the cDNA amplification techniques. The effects of molecules affecting MN survival, neurite extension, and metabolism can easily be defined in vitro, gaining a critical mass of information of immediate clinical application in the treatment of patients affected by ALS. Understanding the properties of human MNs in vitro represents today a significant and critical tool that can easily be reached after extension of the available knowledge from non-primate to human research. Human MN culture studies can greatly contribute to identifying the primitive critical cellular events responsible for the MN degeneration observed in ALS and to gaining crucial information ¶on new therapeutical agents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004150050554
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  • 4
    Electronic Resource
    Electronic Resource
    G7c, a novel gene in the mouse and human major histocompatibility complex class III region, possibly controlling lung tumor susceptibility (2000)
    Springer
    Immunogenetics 51 (2000), S. 383-386 
    Details
    ISSN: 1432-1211
    Keywords: Key words MHC class III region ; Mouse ; Human ; G7c ; Lung tumor susceptibility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050634
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  • 5
    Electronic Resource
    Electronic Resource
    New alleles of human immunoglobulin κ J segments IGKJ2 and IGKJ4 (2000)
    Springer
    Immunogenetics 51 (2000), S. 487-488 
    Details
    ISSN: 1432-1211
    Keywords: Key words Immunoglobulin ; J segments ; IGKJ genes ; Alleles ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002510050647
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of human plasma on the reactivation of sarin-inhibited human erythrocyte acetylcholinesterase (2000)
    Springer
    Archives of toxicology 74 (2000), S. 21-26 
    Details
    ISSN: 1432-0738
    Keywords: Key words Organophosphate ; Acetylcholinesterase ; Oximes ; Human ; Reactivation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The reactivation of organophosphate-inhibited acetylcholinesterase (AChE) by oximes inevitably results in the formation of highly reactive phosphoryloximes (POX), which are able to re-inhibit the enzyme. In this study, the dependence of POX formation on AChE concentration was investigated with sarin-inhibited human erythrocyte AChE (EryAChE). A marked dependence was found with obidoxime but not with the experimental oxime HI 6, suggesting great differences in the decomposition rates of the respective POXs. At a physiological erythrocyte content the reactivation of EryAChE was markedly affected by POX with obidoxime and pralidoxime (2-PAM) but not with the newer oximes HI 6 and HLö 7. Addition of extensively dialysed, sarin-treated human plasma reduced the reactivation by obidoxime and 2-PAM even more. Obidoxime and 2-PAM were superior to HI 6 and HLö 7 in reactivating butyrylcholinesterase (BChE). This effect was pronounced in diluted plasma, but was obscured in concentrated plasma, probably because of re-inhibition by the generated POX. Addition of native erythrocytes to sarin-treated plasma resulted in marked inhibition of EryAChE in the presence of obidoxime, suggesting a higher affinity of the POX for EryAChE. The results indicate that obidoxime and 2-PAM may reactivate sarin-inhibited AChE insufficiently due to re-inhibition by the POX formed. In addition, the re-inhibition of EryAChE may be aggravated by the POX that is produced during BChE reactivation. These reactions must be regarded as therapeutically detrimental and disqualify those oximes which are capable of forming stable POX by reactivation of BChE.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050647
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  • 7
    Electronic Resource
    Electronic Resource
    Species differences in response to diethylhexylphthalate: suppression of apoptosis, induction of DNA synthesis and peroxisome proliferator activated receptor alpha-mediated gene expression (2000)
    Springer
    Archives of toxicology 74 (2000), S. 85-91 
    Details
    ISSN: 1432-0738
    Keywords: Key words Diethylhexylphthalate ; Peroxisome proliferation ; Hepatocarcinogenesis ; Species differences ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Diethylhexylphthalate (DEHP) is a phthalate plasticizer that belongs to the peroxisome proliferator (PP) class of rodent nongenotoxic hepatocarcinogens. Previously, we have shown that MEHP (a principal metabolite of DEHP and the proximal PP) induced DNA synthesis and suppressed apoptosis in rat but not in human hepatocytes in vitro. Here, we present further studies of species differences in response to DEHP. In rats, 4 days of exposure to DEHP (950 mg/kg per day by gavage) induced peroxisomal β-oxidation, DNA synthesis and suppressed apoptosis. In contrast, there was no response of guinea pig liver to DEHP. In rat hepatocytes in vitro, MEHP (250, 500 and 750 μM) induced peroxisomal β-oxidation, DNA synthesis and suppressed apoptosis. In contrast to the pleiotropic response noted in rat hepatocytes, there was no response of human hepatocytes to 250, 500 or 750 μM MEHP. PPs activate the peroxisome proliferator activated receptor alpha (PPARα) that binds to DNA at peroxisome proliferator response elements (PPREs) within the promoters of PP-responsive genes such as rat acyl CoA oxidase (ACO). However, the human ACO gene promoter differs at three bases within the PPRE from the rat ACO promoter and appears refractory to PPs. To address species differences in response to DEHP at the molecular level, we used promoter-reporter gene assays to compare the ability of MEHP to induce gene expression from the rat or the human ACO promoter. MEHP gave a concentration-dependent increase in reporter gene expression from the rat ACO gene promoter with either mouse or human PPARα. In contrast, the human ACO promoter was unable to drive MEHP-induced gene transcription irrespective of the species origin of PPARα. These data provide further weight of evidence at the cellular and molecular levels for a lack of risk to human health from the phthalate DEHP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002040050657
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  • 8
    Electronic Resource
    Electronic Resource
    Striate cortex in humans demonstrates the relationship between activation and variations in visual form (2000)
    Springer
    Experimental brain research 130 (2000), S. 221-226 
    Details
    ISSN: 1432-1106
    Keywords: Key words Visual perception ; Object recognition ; Functional magnetic resonance imaging ; Neuroimaging ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Electrophysiologic and functional imaging studies have shown that the visual cortex produces differential responses to the presence or absence of structure within visual textures. To further define and characterize regions involved in the analysis of form, functional magnetic resonance imaging (fMRI) was used to detect changes in activation during the viewing of four levels of isodipole textures. The texture levels systematically differed in the density of visual features such as extended contours and blocks of solid color present within the images. A linear relationship between activation level and density of structure was observed in the striate cortex of human subjects. This finding suggests that a special subpopulation of striate cortical neurons participates in the ability to extract and process structural continuity within visual stimuli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002210050024
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  • 9
    Electronic Resource
    Electronic Resource
    Ciliogenesis and ciliary abnormalities (2000)
    Springer
    Medical electron microscopy 33 (2000), S. 109-114 
    Details
    ISSN: 1437-773X
    Keywords: Key words Ciliogenesis ; Ciliated cell ; Abnormal cilia ; Basal body ; Ultrastructure ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cilia are motile processes extending from the basal bodies, playing important roles in the mucociliary clearance in the respiratory tract and the transport of the ovum from the ovary to the uterus in mammals. Ciliogenesis is divided into four stages: (1) duplication of centrioles; (2) migration of centrioles to the apical cell surface to become basal bodies; (3) elongation of cilia containing the axoneme; and (4) formation of accessory structures of basal bodies. The orderly course of ciliogenesis appears to be disturbed by various internal and external factors and, as a result, various unusual forms of the ciliary apparatus develop in the cell. Inhibition of basal body migration results in development of intracytoplasmic axonemes, cilia within periciliary sheaths, and intracellular ciliated cysts. Swollen cilia and the bulging type of compound cilia are formed during ciliary budding and elongation. This review also discusses the origin, composition, and function of the centriolar precursor structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007950000009
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  • 10
    Electronic Resource
    Electronic Resource
    The reliability of balance tests performed on the kinesthetic ability trainer (KAT 2000) (2000)
    Springer
    Knee surgery, sports traumatology, arthroscopy 8 (2000), S. 180-185 
    Details
    ISSN: 1433-7347
    Keywords: Keywords Proprioception ; Equilibrium ; Posture ; Reproducibility of results ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Sports Science
    Notes: Abstract The Kinesthetic Ability Trainer (KAT 2000) is a balance platform designed for training and functional testing of the neuromuscular control system. Forty healthy and sports-active persons were tested and 1 month later retested to investigate the reliability of the KAT 2000 testing “one-leg static balance” and “two-leg dynamic balance”. A significant improvement at retesting on the same day was seen in both tests; furthermore the dynamic test result improved significantly with retesting 1 month later. The data obtained made it possible to calculate the 95% confidence limits for an unchanged test result for a single person and a group of persons. The results show a clear learning effect when the persons are retested, especially in the dynamic test. The KAT 2000 can be used as a tool for testing groups of persons both in short- and long-term studies, but it cannot be used for testing single persons due to the great variance in the test results. Further investigations involving injured persons are needed to determine the range of improvement after intervention.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001670050211
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  • 11
    Electronic Resource
    Electronic Resource
    Melanomas with concordant loss of multiple melanocytic differentiation proteins: immune escape that may be overcome by targeting unique or undefined antigens (2000)
    Springer
    Cancer immunology immunotherapy 48 (2000), S. 661-672 
    Details
    ISSN: 1432-0851
    Keywords: Keywords Melanoma ; Antigens ; Cytotoxic ; T lymphocytes ; Human ; Immunotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Melanoma-reactive HLA-A*0201-restricted cytotoxic T lymphocyte (CTL) lines generated in vitro lyse autologous and HLA-matched allogeneic melanoma cells and recognize multiple shared peptide antigens from tyrosinase, MART-1, and Pmel17/gp100. However, a subset of melanomas fail to be lysed by these T cells. In the present report, four different HLA-A*0201+ melanoma cell lines not lysed by melanoma-reactive allogeneic CTL have been evaluated in detail. All four are deficient in expression of the melanocytic differentiation proteins (MDP) tyrosinase, Pmel17/gp100, gp75/trp-1, and MART-1/Melan-A. This concordant loss of multiple MDP explains their resistance to lysis by melanoma-reactive allogeneic CTL and confirms that a subset of melanomas may be resistant to tumor vaccines directed against multiple MDP-derived epitopes. All four melanoma lines expressed normal levels of HLA-A*0201, and all were susceptible to lysis by xenoreactive-peptide-dependent HLA-A*0201-specific CTL clones, indicating that none had identifiable defects in antigen-processing pathways. Despite the lack of shared MDP-derived antigens, one of these MDP-negative melanomas, DM331, stimulated an effective autologous CTL response in vitro, which was restricted to autologous tumor reactivity. MHC-associated peptides isolated by immunoaffinity chromatography from HLA-A1 and HLA-A2 molecules of DM331 tumor cells included at least three peptide epitopes recognized by DM331 CTL and restricted by HLA-A1 or by HLA-A*0201. Recognition of these CTL epitopes cannot be explained by defined, shared melanoma antigens; instead, unique or undefined antigens must be responsible for the autologous-cell-specific anti-melanoma response. These findings suggest that immunotherapy directed against shared melanoma antigens should be supplemented with immunotherapy directed against unique antigens or other undefined antigens, especially in patients whose tumors do not express MDP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002620050015
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  • 12
    Electronic Resource
    Electronic Resource
    Toxicokinetic modelling of methyl formate exposure and implications for biological monitoring (2000)
    Springer
    International archives of occupational and environmental health 73 (2000), S. 479-487 
    Details
    ISSN: 1432-1246
    Keywords: Key words Biological monitoring ; Formate ; Formic acid ; Human ; Methanol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A toxicokinetic (TK) model was developed to describe the inhalation exposure in humans to methyl formate (MF), a catalyst used in foundries, and to discuss biological monitoring. The TK model consisted of four compartments: MF, the metabolites – methanol (MeOH) and formic acid (FA) – and, in addition, a urinary compartment describing the saturable reabsorption of FA. Levels of MeOH and FA in urine, from an experimental study (100 ppm MF, 8 h at rest), validated the present model. The TK model describes well the general behaviour of MeOH and FA in urine after MF exposure. A nonlinear and a linear relationship respectively, was predicted between MF exposure and FA or MeOH excretion in urine, and this has previously been seen after occupational MF exposure. The present model has been modified to simulate MeOH exposure as well. Generally low exposures (concentration or exercise) produce only marginal increases in FA urinary excretions, but when exposure is elevated, urinary FA excretion increases because of saturation in the mechanism of reabsorption. Using FA urinary excretion as the critical indicator, because of its link to health effects, an occupational exposure limit value for MF of no greater than 50 ppm should be selected (based on predictions with the TK model). MeOH in urine can be considered as a biomarker for MF at low exposure, because of lower background values and of a linear relationship with exposure. At higher exposures, however, FA could be used as a biomarker as it becomes progressively more sensitive. But the use of biological monitoring for MF is difficult because of individual variations in background values. Under the present state of knowledge both FA and MeOH should be used to estimate only group exposures, rather than individual exposures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004200000170
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  • 13
    Electronic Resource
    Electronic Resource
    Biological Features of Premalignant Disease in the Human Breast (2000)
    Springer
    Journal of mammary gland biology and neoplasia 5 (2000), S. 351-364 
    Details
    ISSN: 1573-7039
    Keywords: Human ; breast cancer ; premalignant
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Most human invasive breast cancers (IBCs)4 arise from preexisting benign lesions. There are many types of benign lesions in the human breast and only a few appear to have significant premalignant potential (atypical hyperplasias and in situ carcinomas). These lesions are relatively common and only a small proportion progress to IBC. They are currently defined by their histological features and their prognosis is imprecisely estimated from indirect evidence based on epidemiological studies. Although lesions within specific categories look alike, they must possess morphologically silent biological differences motivating some to remain stable and others to progress. Understanding the biological changes responsible for the development and progression of premalignant disease is a very active area of medical research. Progress in this area may provide new opportunities for breast cancer prevention by providing strategies to treat premalignant lesions before they develop or become cancerous. A large number of biological features have been evaluated in this setting during the past decade. This review discusses a few features that appear to be particularly important and have been studied in a relatively comprehensive manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009573710675
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  • 14
    Electronic Resource
    Electronic Resource
    Identification and molecular cloning of cathepsin P, a novel human putative cysteine protease of the papain family (2000)
    Springer
    Pflügers Archiv 439 (2000), S. r116 
    Details
    ISSN: 1432-2013
    Keywords: Key words cDNA ; Human ; Cathepsin P ; Propeptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A cDNA encoding a novel human putative member of the papain family of cysteine peptidases has been cloned. The protease, named cathepsin P, is synthesized as a preproprotein. The presumed propeptide of 38 amino acids is followed by a 242-residue mature protein. The mature protease region is 30% identical to human papain-like cathepsins, with all the residues important for catalysis conserved. No similarity was observed in the propeptide region. On the contrary, the proenzyme shares 51-87% residues with some precursors of cysteine proteases from other species that have not yet been characterized. They all show a nearly completely conserved “CYTRED motif” in the propeptide region, not present in other members of the family, and could therefore constitute a distinct subfamily.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004240000112
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  • 15
    Electronic Resource
    Electronic Resource
    Preliminary functional analysis of human epidermal T cells (2000)
    Springer
    Archives of dermatological research 292 (2000), S. 9-15 
    Details
    ISSN: 1432-069X
    Keywords: Key words Epidermal T cells ; Function ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The function of human epidermal T cells (ETC) is unknown. In the present study, dermal T cells (DTC), ETC and keratinocytes were cultured from normal human skin. DTC and ETC lines were expanded in medium containing interleukin 2. The autologous keratinocytes were transfected with a human papillomavirus 16 E6 and E7 plasmid to produce an immortal keratinocyte line “HEK001”. Lymphocyte migration and adhesion to HEK001 was assessed in calcein fluorimetric assays. ETC migrated towards HEK001 three to four times more than DTC. ETC adhered to HEK001 two to four times more than DTC. The proportion of ETC expressing the cutaneous lymphocyte-associated antigen was greater than that of DTC (26% and 1%, respectively). The keratinocyte line HEK001 expressed ICAM-1 following stimulation with TNF-α or IFN-γ and following coculture with autologous cutaneous T cells. A blocking anti-ICAM-1 antibody reduced DTC and ETC adhesion to HEK001 by 30% and 50%, respectively. Therefore, cutaneous T cells may upregulate keratinocyte ICAM-1 expression which mediates adhesion to autologous keratinocytes. These results are consistent with the hypothesis that the ETC and DTC populations are distinct. Both directed migration (epidermotropism) and selective retention may be involved in the development and maintenance of the ETC population in normal human skin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00007461
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  • 16
    Electronic Resource
    Electronic Resource
    Predicting haloperidol occupancy of central dopamine D2 receptors from plasma levels (2000)
    Springer
    Psychopharmacology 149 (2000), S. 1-5 
    Details
    ISSN: 1432-2072
    Keywords: Key words Haloperidol ; Dopamine ; Receptor occupancy ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Positron emission tomography (PET) is increasingly being used to study dopamine receptor occupancy and the clinical effects of antipsychotic medication. Dopamine D2 receptor occupancy has been shown to predict several clinical effects of antipsychotic medication including therapeutic response, motor and endocrine side-effects. Plasma levels may be used as a surrogate marker for central occupancy if the relationship between these two measures may be accurately described. This study was designed to test the capacity of a previously derived relationship equation (%D2 occupancy=plasma level/ED50+plasma level, where ED50= 0.40 ng/ml) to predict striatal D2 occupancy from plasma level. Twenty-one patients receiving treatment with low dose haloperidol underwent a 11C-raclopride PET scan to measure D2 occupancy. The D2 occupancy levels were accurately predicted by use of the previously generated equation with only a small degree of error (3.89% CI 0.45–7.33). Predicted and measured D2 occupancy values correlated closely (Pearson’s r=0.864, P=0.003). The study indicates that reliable prediction of D2 occupancy from plasma levels is possible. This provides a potentially useful surrogate measure of D2 occupancy for research and possibly clinical practice, as the routine use of PET to measure occupancy levels is not feasible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002139900333
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  • 17
    Electronic Resource
    Electronic Resource
    Reinforcing and subjective effects of morphine in human opioid abusers: effect of dose and alternative reinforcer (2000)
    Springer
    Psychopharmacology 148 (2000), S. 272-280 
    Details
    ISSN: 1432-2072
    Keywords: Key words Opioids ; Self-administration ; Progressive ratio ; Drug abuse ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Although most opioid self-administration research has been conducted with laboratory animals, such research with humans is necessary to answer questions unique to human drug-taking behavior. Objective: We investigated the influence of morphine dose and an alternative non-drug reinforcer on choice between morphine versus money and examined the relationship between drug-reinforced behavior and subjective euphoria. Methods: Five male opioid users participated in the 7-week study. During the first 5 weeks, a single dose of morphine (0, 4, 8, 16, or 32 mg/70 kg) was available each week. On Monday, subjects received an IM injection of the dose tested that week. On Tuesday, Thursday, and Friday, subjects could work for morphine or money under a second-order, progressive ratio schedule. For each primary ratio completed on the drug lever, subjects earned one-ninth of the available drug dose, and for each ratio completed on the money lever, subjects earned $1. Total amount of drug earned was administered in a single IM injection at the end of the session; money earned was credited to the subject’s account. Results: As morphine dose increased, responding for drug increased in an orderly manner and responding for money decreased. During the final phase of the study, the lowest and highest doses that maintained drug responding for each subject were repeated, and the value of the alternative reinforcer was increased to $2 per ratio. This manipulation was associated with decreased drug-maintained responding at the lowest, but not the highest, reinforcing dose of morphine. Conclusion: The progressive ratio, concurrent access procedure may be useful in predicting the outcome of drug abuse treatment interventions that use alternate reinforcement strategies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050051
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  • 18
    Electronic Resource
    Electronic Resource
    Abuse liability assessment of sibutramine, a novel weight control agent (2000)
    Springer
    Psychopharmacology 147 (2000), S. 339-346 
    Details
    ISSN: 1432-2072
    Keywords: Key words Sibutramine ; d-Amphetamine ; Abuse potential ; Subjective effect ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Sibutramine (Meridia) is a serotonin and norepinephrine reuptake inhibitor marketed for weight control. Previous studies demonstrated low abuse potential for 20 and 30 mg sibutramine (doses near the therapeutic range); however, no data existed on supratherapeutic doses. This study, therefore, examined 25 and 75 mg sibutramine in humans compared to d-amphetamine (20 mg) as a positive control and placebo as a negative control. Objectives: The study examined the acute subjective, reinforcing, and physiological effects of sibutramine to assess its abuse liability. Methods: Twelve polydrug abusers with no history of drug dependence participated in this double-blind, inpatient/outpatient study. Volunteers participated in four drug sessions, in which they completed subjective effects scales including the Profile of Mood States (POMS), Visual Analog Scales (VAS), and the Addiction Research Center Inventory (ARCI). The Multiple Choice Procedure (MCP) was used to evaluate reinforcing efficacy. Results: Sibutramine 25 mg produced subjective effects that were indistinguishable from placebo. Sibutramine 75 mg produced significant unpleasant effects, such as Anxiety, Confusion, and decreased Vigor. On the MCP, volunteers chose to give up an average of $4.04 from their study pay rather than receive the higher dose of sibutramine again. In contrast, d-amphetamine 20 mg produced positive mood changes and was well liked. Conclusions: These data indicate sibutramine lacks amphetamine-type abuse liability when administered acutely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050001
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  • 19
    Electronic Resource
    Electronic Resource
    Conditioned effects of environmental stimuli paired with smoked cocaine in humans (2000)
    Springer
    Psychopharmacology 149 (2000), S. 24-33 
    Details
    ISSN: 1432-2072
    Keywords: Key words Cocaine ; Conditioning ; Cardiovascular effect ; Subjective effect ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Clinical data suggest that stimuli paired with cocaine use acquire emergent stimulus effects, such as the ability to elicit cocaine craving. Objectives: The purpose of this study was to determine the conditioned effects of neutral stimuli paired with cocaine smoking. Methods: Eight experienced adult cocaine smokers participated in 22 experimental sessions while residing on a Clinical Research Center. One set of cues (CS–) was paired with placebo smoked cocaine and one set of cues (CS+) was paired with 25 mg smoked cocaine. Results: After 18 training trials, the effects of cocaine on heart rate and ratings of ”anxious” were greater, and skin temperature and ratings of ”tired” were smaller when compared to the effects of cocaine after the first training trial. When instructed to select a cue to experience after training, seven of eight participants selected the CS+, while only three of the participants selected the CS+ prior to training, i.e., the CS+ functioned as a conditioned reinforcer. Presentation of the CS+ alone without cocaine during extinction trials increased HR, SP, and ratings of ”anxious””tired”, and ”I want cocaine” and decreased skin temperature. These changes elicited by presentation of the CS+ decreased over the course of the extinction sessions. Conclusions: The present results indicate that classical conditioning is one mechanism by which stimuli paired with cocaine acquire emergent stimulus effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002139900340
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  • 20
    Electronic Resource
    Electronic Resource
    Magnetic resonance spectroscopy of brain in epilepsy (2000)
    Springer
    Child's nervous system 16 (2000), S. 235-241 
    Details
    ISSN: 1433-0350
    Keywords: Key words Magnetic resonance spectroscopy ; Epilepsy ; Brain metabolism ; GABA ; N-Acetyl aspartate ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The current applications of magnetic resonance spectroscopy (MRS) in the clinical management of epileptic patients are reviewed. A major contribution of MRS to epilepsy is its ability to determine lateralisation before surgical resection of the diseased brain region. Phosphorus-31 and proton single-voxel MRS identify abnormalities in high-energy metabolism, neuronal function and neurotransmitter levels, but information can only be obtained from restricted regions of the brain. Spectroscopic imaging techniques (also known as chemical shift imaging) provide a metabolic mapping of the whole brain. They expand the range of applications of MRS to other types of epilepsy (neocortical, frontal) than temporal lobe epilepsy, which is the most often studied. Also, spectral editing techniques in proton MRS make it possible to detect and monitor drug-induced variations of GABA in the human brain, opening new insights into patient response to drug therapy of epilepsy. MRS is playing an increasing role in the noninvasive characterisation and management of epileptic patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003810050504
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  • 21
    Electronic Resource
    Electronic Resource
    Transdifferentiation of somatotrophs to thyrotrophs in the pituitary of patients with protracted primary hypothyroidism (2000)
    Springer
    Virchows Archiv 436 (2000), S. 43-51 
    Details
    ISSN: 1432-2307
    Keywords: Key words Pituitary ; Human ; Somatotroph ; Thyrotroph hyperplasia ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  In patients with protracted primary hypothyroidism, the pituitary is enlarged due to the lack of feedback inhibition by thyroid hormone. In the present work, adenohypophysial biopsies from three women with protracted primary hypothyroidism were investigated by routine histology, immunocytochemistry, double immunostaining, immunoelectron microscopy, and combined immunocytochemistry – in situ hybridization. These methods confirmed the presence of massive thyrotroph hyperplasia and the formation of ”thyroidectomy” or ”thyroid deficiency” cells. A number of thyroidectomy cells were found to be immunoreactive for growth hormone (GH). Double immunostaining and immunoelectron microscopy revealed the presence of bihormonal cells containing both GH and thyroid stimulating hormone (TSH). Immunostaining combined with in situ hybridization revealed GH immunoreactive cells expressing TSH mRNA as well as TSH immunopositive cells expressing GH mRNA. Our findings provide conclusive evidence that somatotrophs may transform to thyrotrophs. Thus, in addition to multiplication of thyrotrophs, transdifferentiation of GH cells to thyrotrophs contributes to the increase of TSH-producing cells. The presence of such bihormonal cells best termed ”thyrosomatotrophs” supports the concept that adenohypophysial cells are not irreversibly committed to the production of one single hormone and that their phenotype can change in response to functional demand.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00008197
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  • 22
    Electronic Resource
    Electronic Resource
    Centriacinar region inflammatory disease in young individuals: a comparative study of Miami and Los Angeles residents (2000)
    Springer
    Virchows Archiv 437 (2000), S. 422-428 
    Details
    ISSN: 1432-2307
    Keywords: Keywords Lung ; Ozone ; Centriacinar ; Human ; Autopsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Semiquantitative measurements of chronic inflammation of the centriacinar region (proximal acinus of lung) were compared between 20 Miami and 18 Los Angeles residents (ages 11–30 years) for whom smoking histories were available. Mean extent and severity scores of four lung sites were higher for Los Angeles than Miami residents, with effect of city statistically significant for extent (P=0.02). Also, maximum scores for extent and severity by city were significantly greater for Los Angeles residents (P=0.02, each), but not by smoking history. Smokers did have higher scores for mean extent and severity (by lung site and smoking history), but neither this nor inclusion of smoking and city in the model reached significance. With respect to maximum extent and maximum severity scores, a stratified comparison of cities by smoking history showed a trend (not significant) toward higher scores for Los Angeles residents. Mean extent and severity scores for the lower lobe were higher for basilar sections than for apical sections (each P〈0.001). Cumulative data indicate that expanded pathologic studies are essential for efforts to complete a convergence of epidemiological and experimental data implicating exceedences of the Federal ozone standard as a contributor to human lung injury.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004280000262
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  • 23
    Electronic Resource
    Electronic Resource
    Rejection and tacrolimus conversion therapy in paediatric liver transplantation (2000)
    Springer
    Transplant international 13 (2000), S. S341 
    Details
    ISSN: 1432-2277
    Keywords: Key words Liver transplantation ; Rejection ; Tacrolimus ; Human ; Child
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Rejection and efficacy of rescue therapy with tacrolimus were evaluated in 50 children who underwent primary, ABO-compatible, liver transplantation. Six patients who died within the first week and one child who underwent retransplantation from an ABO-incompatible donor were excluded from the study. No patient or graft were lost due to rejection. We observed 48 episodes of rejection in 33 patients. Fourteen patients required conversion to tacrolimus for steroid-resistant rejection with resolution of rejection. One of these children developed PTLD. Other indications for conversion were neurotoxicity and hirsutism. One patient developed blindness of unknown origin after the conversion. Other side effects of tacrolimus were minor and resolved by lowering the dose. Five patients developed rejection after conversion; all achieved resolution with either steroid therapy or increase of tacrolimus dose. In conclusion, our study confirms that tacrolimus is an effective rescue therapy for paediatric liver transplantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001470050357
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  • 24
    Electronic Resource
    Electronic Resource
    Caffeine withdrawal increases cerebral blood flow velocity and alters quantitative electroencephalography (EEG) activity (2000)
    Springer
    Psychopharmacology 147 (2000), S. 371-377 
    Details
    ISSN: 1432-2072
    Keywords: Key words Cerebral blood flow velocity ; EEG ; Caffeine ; Withdrawal ; Physical dependence ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Rationale: Cessation of daily caffeine consumption produces a withdrawal syndrome comprised of subjective symptoms and functional impairment. Few controlled studies have examined the physiological effects of caffeine withdrawal. Objective: The present study examined the effect of caffeine withdrawal on cerebral blood flow velocity and quantitative EEG. Methods: Ten volunteers reporting moderate caffeine intake (mean 333 mg/day) participated in this double-blind study. Subjects completed several tests when maintaining their normal diet (baseline period) and during two 1-day periods during which they consumed caffeine-free diets and received capsules containing placebo (placebo test session) or caffeine (caffeine test session) in amounts equal to their baseline daily caffeine consumption. Blood flow velocity was determined for four arteries: right and left middle (MCA), and right and left anterior (ACA) cerebral arteries using pulsed transcranial Doppler sonography. EEG was recorded for 3 min from eight scalp sites while subjects sat, with eyes closed, in a sound-attenuated electronically shielded chamber. Subjective effects were assessed with questionnaires. Results: Results showed an effect of the placebo (21-h withdrawal) condition compared to the caffeine condition. Placebo significantly increased the mean velocity, systolic velocity and diastolic velocity (cm/s) in all four cerebral arteries. In the MCA, the pulsatility index was significantly decreased following placebo. Placebo significantly increased EEG theta power. Placebo also produces subjective effect changes, including increases in heavy feelings in arms and legs and decreases in ability to concentrate. The caffeine and baseline conditions produced similar results on both the physiological and subjective measures. Conclusion: Cessation of daily caffeine consumption produced changes in cerebral blood flow velocity and quantitative EEG. These changes may be related to classic caffeine withdrawal symptoms of headache, drowsiness and decreased alertness.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002130050005
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  • 25
    Electronic Resource
    Electronic Resource
    Precancerous conditions for pancreatic cancer (2000)
    Springer
    Journal of hepato-biliary-pancreatic surgery 7 (2000), S. 575-579 
    Details
    ISSN: 1436-0691
    Keywords: Key words Precancerous conditions ; Pancreatic duct adenocarcinoma ; Hamster ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Precancerous conditions for ductal adenocarcinoma of the pancreas in hamsters and human beings are discussed. In hamsters, ductal adenocarcinomas induced by nitrosamines are of nonmucin-hypersecreting tubular or papillary tumor types, and genetic alterations resembling these types are found in their human counterparts. Ductal lesions develop step-by-step from hyperplasias to carcinomas, and atypical ductal cell hyperplasias may be precancerous. In humans, ductal lesions, hyperplasias, or dysplasias, with or without mucin hypersecretion, are possible preneoplastic conditions. Genetic or phenotypic markers to determine their likelihood of progressing to pancreatic duct adenocarcinomas are a high priority for future research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005340070006
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  • 26
    Electronic Resource
    Electronic Resource
    Differential expressions of protein kinase C isozymes during proliferation and differentiation of human skeletal muscle cells in vitro (2000)
    Springer
    Acta neuropathologica 99 (2000), S. 96-104 
    Details
    ISSN: 1432-0533
    Keywords: Key words Skeletal muscle ; Human ; Differentiation ; Protein kinase C ; Isozymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The mechanism of skeletal muscle regeneration in vivo can be well modeled in vitro by culturing skeletal muscle cells. In these cultures mononuclear satellite cells fuse to form polynuclear myotubes by proliferation and differentiation. The aim of this study was to determine how the different protein kinase C (PKC) isozymes were expressed during differentiation of human skeletal muscle in vitro. The expressions of desmin, used as a muscle-specific intermediate filament protein marker of differentiation, and of different PKC isozymes were detected by single and double immunohistochemical labeling, and by Western blot analysis. In skeletal muscle cells we could identify five PKC isozymes (PKCα, -γ, -η, -θ and -ζ). The expressions of PKCα and -ζ did not change significantly during differentiation; their levels of expression were high in the early immature cells and remained unchanged in later phases. In contrast, the expression levels of PKCγ and -η increased with differentiation. Furthermore, the cellular localization of PKCγ markedly altered during differentiation, with a perinuclear-nuclear to cytoplasmic translocation. The change in the level of expression of PKCθ during differentiation showed different pattern; its expression was high during the early phases, but a decreased immunostaining was detected in the matured, well-differentiated myotubes. We conclude, therefore, that cultured human skeletal muscle cells possess a characteristic PKC isozyme pattern, and that the different phases of differentiation are accompanied by different expression patterns of the various isozymes. These data suggest the possible functional and differential roles of PKC isozymes in human skeletal muscle differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00007429
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  • 27
    Electronic Resource
    Electronic Resource
    Intraoperative endogenous erythropoietin levels and changes in intravascular blood volume in healthy humans (2000)
    Springer
    Annals of hematology 79 (2000), S. 183-186 
    Details
    ISSN: 1432-0584
    Keywords: Key words Erythropoietin ; Endogenous ; Blood volume ; Human ; Intraoperative
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  There is accumulating evidence of a relationship between changes in intravascular blood volume and endogenous erythropoietin (EPO) levels. In this study, eight healthy adult American Society of Anesthesiologists class-I patients due for prolonged elective surgery were randomised either to preoperative hypervolaemic haemodilution using hydroxyethyl starch, followed by intraoperative crystalloid infusion, or to standard intraoperative normovolaemic fluid balance management using crystalloids (control group). Electrolytes, creatinine, urea, osmolality, urine output and blood gases were monitored pre- and intraoperatively for 6 h, Comparable cardiopulmonary and renal homeostasis were maintained in both groups. We found that central venous pressure increased and EPO levels decreased, both significantly, in the hypervolaemic haemodilution group relative to controls. There were no significant intergroup changes in any other parameters. By controlling for other known determinants of EPO levels, our data indicate a relationship between EPO levels and changes in intravascular blood volume in humans, supporting the notion of EPO as a volume-regulated, and possibly volume-regulating, hormone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002770050577
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  • 28
    Electronic Resource
    Electronic Resource
    The human epithelial cell cytotoxicity assay for determining tissue specific toxicity (2000)
    Springer
    Methods in cell science 22 (2000), S. 17-24 
    Details
    ISSN: 1573-0603
    Keywords: Albumin ; Bronchial cells ; Chemoprevention ; Ecto-cervical cells ; Growth inhibition ; Hepatocytes ; Human ; In vitro ; Keratinocytes ; Mammary epithelial cells ; Mitochondrial function ; Normal ; Oral mucosal cells ; PCNA ; Prostate epithelial cells ; Renal cells ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Human Epithelial Cell Cytotoxicity (HECC) Assay for determining organ specific cytotoxicity uses human epithelial cells from eight different human tissues, including: skin, mammary, prostate, renal, bronchial, oral, ecto-cervix, and liver. Although the initial studies using this assay were conducted using cancer chemopreventive agents, the HECC Assay can also be used to evaluate other types of drugs, personal care products, environmental chemicals, and potential toxicants. Human epithelial cells at an early passage are seeded into multi-well dishes. The cells are exposed to multiple concentrations of a test agent for a three day period. The concentration ranges for test agents in the assay are determined in a preliminary assay using an exposure of five days and log dilutions from the highest soluble concentration. At the end of the exposure period, the cultures are evaluated for inhibition of growth. In the HECC Assay, cultures are exposed for three days. At the end of the exposure period, the cultures are evaluated for inhibition of growth, mitochondrial function, and PCNA expression or albumin synthesis (hepatocytes). Data are analyzed to determine the concentration that inhibited and point by 50 percent (TC50). Values for each agent in each target epithelial cell line or culture and the target tissue specific sensitivity are compared to determine the relative sensitivity of each epithelial cell line to the test agent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009832830130
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  • 29
    Electronic Resource
    Electronic Resource
    Hypertensive renovasculopathies and the rise of blood pressure with age in Japan and USA (2000)
    Springer
    International urology and nephrology 32 (2000), S. 109-117 
    Details
    ISSN: 1573-2584
    Keywords: Aging ; Nephrosclerosis ; Arteriolosclerosis ; Hypertension ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Arterial intimal fibroplasia in renal interlobular arteries but not arteriolar hyalinization was reported to be proportional to the rise of blood pressure with age in the data from all populations examined so far. New findings from Japan offer further insights into the disparities between the two types of renovasculopathy, both of which are called by the same name, `arteriolosclerosis'. PAS stained paraffin sections were prepared from specimens obtained atautopsy in Tokyo and New Orleans, emphasizing basal subjects, i.e. those with no cause of deathknown to be related to hypertension. Severities of fibroplastic vasculopathy, in units of intimal thickness as % of outer diameter, and hyaline vasculopathy, in units of affected arterioles per cm2 of tissue sectional area, were measured morphometrically. Blood pressure data were taken from published population surveys. Fibroplastic renovasculopathy was found to provide a proxy for mean blood pressure (MBP) when comparing groups of men and women of various age groups in the USA and Japan. Hyaline renovasculopathy did not reproduce these patterns. Some of these findings confirm similar results from prior studies, and this reproducibility increases confidence that a true biological difference may exist between these populations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007119132063
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  • 30
    Electronic Resource
    Electronic Resource
    Postoperative colonic motility and tone in patients after colorectal surgery (2000)
    Springer
    Diseases of the colon & rectum 43 (2000), S. 932-939 
    Details
    ISSN: 1530-0358
    Keywords: Barostat ; Colon ; Human ; Ileus ; Manometry ; Motility ; Postoperative ; Rectum ; Surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract PURPOSE: Colonic motility is crucial for the resolution of postoperative ileus. However, few data are available on postoperative colonic motility and no data on postoperative colonic tone. We aimed to characterize postoperative colonic tone and motility in patients. METHODS: Nineteen patients were investigated with combined barostat and manometry recordings after left colonic surgery. During surgery a combined recording catheter was placed in the colon with two barostat bags and four manometry channels cephalad to the anastomosis. Recordings were performed twice daily from Day 1 to Day 3 after surgery. RESULTS: Manometry showed an increasing colonic motility index, which was a mean (± standard error of the mean) of 37±5 mmHg/minute on Day 1, 87±19 mmHg/minute on Day 2, and 102±13 mmHg/minute on Day 3 (P〈0.05 for Day 1vs. Day 2 and Day 2vs. Day 3). Low barostat bag volumes indicating a high colonic tone were observed on Day 1 after surgery and increased subsequently (barostat bag I was 19±4, 32±6, and 32±6 ml; barostat bag II was 13±1, 19±3, and 22±5 ml on Days 1, 2, and 3, respectively; for both barostat bagsP〈0.05 for Day 1vs. Day 2 but not Day 2vs. Day 3). CONCLUSIONS: Colonic motility increased during the postoperative course. The low barostat bag volumes indicated a high colonic tone postoperatively which would correspond to a contracted rather than to a distended colon. High colonic tone postoperatively may be relevant for pharmacologic treatment of postoperative ileus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02237353
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  • 31
    Electronic Resource
    Electronic Resource
    Separation and Detection of Metal Ions in Ecological Samples by Capillary Zone Electrophoresis with Indirect UV Detection (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 511-514 
    Details
    ISSN: 0935-6304
    Keywords: CZE ; indirect UV detection ; metal ions ; ecological samples ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 32
    Electronic Resource
    Electronic Resource
    Determination of Cinnamomi Constituents by High-performance Liquid Chromatography and Capillary Electrophoresis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 561-564 
    Details
    ISSN: 0935-6304
    Keywords: Retention factors ; Cinnamomi ramulus ; high-performance liquid chromatography ; capillary electrophoresis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 33
    Electronic Resource
    Electronic Resource
    Ion Chromatography of Inorganic Anions on Graphitic Carbon as the Stationary Phase (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 590-594 
    Details
    ISSN: 0935-6304
    Keywords: Ion chromatography ; graphitic carbon stationary phases ; anions ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Inorganic anions could be separated on porous graphitic carbon stationary phases in ion chromatography. Ion exchange between eluent anions and sample anions on the stationary phase was confirmed by the retention behavior and the possibility of indirect photometric detection. The elution order of anions was different from that observed for commercially available anion exchangers. Chloride, nitrate, and sulfate contained in tap water could be determined in 7 min.
    Additional Material: 6 Ill.
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  • 34
    Electronic Resource
    Electronic Resource
    Characteristic Stationary Phase Constants for Two Popular Open-Tubular Column Stationary Phases for Gas Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 603-608 
    Details
    ISSN: 0935-6304
    Keywords: Solvation parameter model ; ystem constants for poly(dimethyldiphenylsiloxane) HP-5 and poly(ethylene glycol) HP-INNOWax stationary phases ; temperature ; molecular interaction ; retention models ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 35
    Electronic Resource
    Electronic Resource
    Characterization of Inulins by Capillary Electrophoresis with Laser Induced Fluorescence Detection (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 656-658 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis (CE) ; laser induced fluorescence detection (LIFD) ; fluorescein isothiocyanate (FITC) ; inulin ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 36
    Electronic Resource
    Electronic Resource
    RP-HPLC Method for the Separation of Some Phenol Derivatives Using Gradient Elution and UV Detection (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 699-701 
    Details
    ISSN: 0935-6304
    Keywords: Phenol derivatives ; RP-HPLC separation ; short RP column ; gradient elution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 1 Ill.
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  • 37
    Electronic Resource
    Electronic Resource
    Solid-Phase Microextraction of Pyrethroid Pesticides from Water at Low and Sub-ppt Levels at Different Temperatures (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 485-488 
    Details
    ISSN: 0935-6304
    Keywords: Pyrethroids ; solid-phase microextraction ; water analysis ; temperature ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Synthetic pyrethroids are increasingly being used for insect control on field crops because of their advantageous environmental properties such as short field life, broad spectrum of insecticide activity, and relatively low mammalian toxicity. In the present work, experimental conditions were optimized for trace analysis of pyrethroids in water by using solid-phase microextraction followed by capillary gas chromatography. Effects of temperature, SPME-fiber diameter, and matrix were studied. SPME used off-line with a gas chromatograph electron-capture detection (GC-ECD) showed a linear response over a wide concentration range. Our results showed a strong temperature effect on pyrethroid extraction yield. The detection limit after 5 min of SPME-fiber exposure to the samples changed from 1 ppb (at 30°C) to 0.1 ppt (at 90°C), which is a 10000 increase in pyrethroid detection. The standard deviations of the analyte peak area ratios were typically in the range of 1-7% at 30°C and of 3 to 15% at 90°C. Best conditions for pyrethroids analysis were achieved using high temperature solution and a 100 μm polydimethylsiloxane fiber. No matrix (river water) influence was observed on detection of the investigated pyrethroids.
    Additional Material: 6 Ill.
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  • 38
    Electronic Resource
    Electronic Resource
    Group-Type Identification of Oil Samples Using Comprehensive Two- Dimensional Gas Chromatography Coupled to a Time-of-Flight Mass Spectrometer (GC×GC-TOF) (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 507-510 
    Details
    ISSN: 0935-6304
    Keywords: Comprehensive two-dimensional GC ; time-of-flight ; oil analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---In this work a comprehensive two-dimensional system (GC×GC) was coupled to a time-of-flight mass spectrometer (TOF/MS) for the analysis of oil samples. Group-types like the alkanes and saturated cyclic compounds (naphthenes), which are present in oil, are shown separately by selecting their unique masses. On selecting appropriate ion fragments, this method also permits the determination of sulfur- and oxygen-containing species in oil. Former results obtained by FID detection could be confirmed. After proper selection of unique ions in GC×GC-TOF both selectivity and sensitivity increase.
    Additional Material: 6 Ill.
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  • 39
    Electronic Resource
    Electronic Resource
    Sympathetic stimulation induced by hand cooling alters cold-induced vasodilatation in humans (2000)
    Springer
    European journal of applied physiology 81 (2000), S. 303-309 
    Details
    ISSN: 1439-6327
    Keywords: Key words Local cold ; Extremities ; Cold induced vasodilatation ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Hand cooling is a cold pressor test, which induces general sympathetic stimulation. This cooling procedure is often performed to investigate cold induced vasodilatation (CIVD) in one finger. To investigate the effects of this sympathetic stimulation on local CIVD, 12 subjects immersed either the right index finger (T1), right hand (T2) or left hand and right index finger (T3) for 30 min in water at 5°C followed by 15-min recovery. Skin temperature and skin blood flow (Q˙ sk) measured by laser Doppler flowmetry on the right index finger, as well as heart rate (f c) and mean arterial blood pressure ( ), were continuously monitored during the three tests. Cutaneous vascular conductance was calculated as Q˙ sk/ . Concentrations of plasma noradrenaline (NA) and adrenaline (AD) were measured at different times during the tests. The results showed no cardiovascular change in T1, whereas f c and increased significantly at the beginning of both T2 and T3. Similarly, sympathetic stimulation was reflected in the NA concentrations, which increased significantly (P 〈 0.01) during T2 and T3 after 5 min of immersion, and remained elevated until the recovery period. The AD concentration did not change during the three tests. During T2, the CIVD appeared later and slower in comparison with T1 [CIVD onset: 12.81 (SEM 2.30) min in T2 and 5.62 (SEM 0.33) min in T1] . During T3, the CIVD onset was not delayed compared to T1 [6.38 (SEM 0.67) min], but the rewarming was lower [+5.40 (SEM 0.86)°C in T3 and +9.10 (SEM 1.31)°C in T1]. These results showed that CIVD could be altered by sympathetic stimulation but it also appeared that the onset of CIVD could be influenced by local cooling, independently of the general sympathetic stimulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050047
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    Electronic Resource
    Electronic Resource
    Leg-press resistance training during 20 days of 6° head-down-tilt bed rest prevents muscle deconditioning (2000)
    Springer
    European journal of applied physiology 82 (2000), S. 30-38 
    Details
    ISSN: 1439-6327
    Keywords: Key words Bed rest ; Resistance training ; Skeletal muscle ; Physiological cross-sectional area ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of this study was to investigate the effects of resistance training on the morphological and functional properties of human lower limb muscles during 20 days of 6° head-down-tilt bed rest. Nine men were randomly assigned to the resistance training group (BR-Tr, n=5) or the non-training, control group (BR-Cont, n=4). Isometric leg-press exercises were performed: 3 s × 30 repetitions (30 s rest between repetitions) daily for 20 days during the bed-rest period. Serial axial magnetic resonance images were taken from the right thigh and leg muscles, and muscle volume, muscle length, and fibre length were estimated. The physiological cross-sectional areas (PCSAs) of the knee extensor, knee flexor, ankle plantarflexor, and ankle dorsiflexor (tibialis anterior) muscle groups were determined as muscle volume multiplied by the cosine of the angle of fibre pennation divided by fibre length. Maximum voluntary contraction (MVC) during knee extension was measured. No significant changes were observed in the PCSA of the knee extensor muscles in BR-Tr group, whereas the PCSA in the BR-Cont group decreased by 7.8%. The PCSA of the knee flexor and plantarflexor muscles in the BR-Tr group and BR-Cont group significantly decreased after bed rest (knee flexors, 10.2% and 11.5%; plantarflexors, 13.0% and 12.8%, respectively). However, in both groups bed rest had no effect on the muscle volume and PCSA of the tibialis anterior. MVC was maintained by resistance training in the BR-Tr group (decreased by 1%). In contrast, a decline of strength was observed in the BR-Cont group (−16%), but this result was not statistically significant. These results suggest that isometric leg-press training prevents the deconditioning (i.e. atrophy and decline of strength) of the knee extensor muscle group.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050648
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    Electronic Resource
    Electronic Resource
    Changes in muscle afferents, motoneurons and motor drive during muscle fatigue (2000)
    Springer
    European journal of applied physiology 83 (2000), S. 106-115 
    Details
    ISSN: 1439-6327
    Keywords: Key words Central fatigue ; Muscle fatigue ; Human ; Motor cortex ; Motoneuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fatigue is a reduction of maximal muscle force or power that occurs with exercise. It is accompanied by changes at multiple levels in the motor pathway and also by changes in the discharge patterns of muscle afferents. Changes in afferent firing can lead to altered perceptions and can also act on the efferent pathway. Changes in the motor pathway include slowing of motor unit firing rates during sustained maximal voluntary contractions (MVCs). Muscle responses to stimulation at different levels of the motor pathway also change. Transcranial magnetic stimulation of the motor cortex and stimulation of descending tracts in the spinal cord in human subjects show an increase in the response of the cortex and a decrease in response of the motoneuron pool during sustained MVCs. In addition, the silent period following magnetic stimulation is prolonged. During relaxation after fatiguing exercise, muscle responses to stimulation of the motor cortex are initially facilitated and are then depressed for many minutes, whereas responses to descending tract stimulation are initially depressed but recover over about 2 min. Although some of the loss of force of fatigue does occur through inadequate drive to the muscle, it is not clear which, if any, of the changes described in the cortex or the motoneurons are responsible for loss of maximal voluntary force and thus contribute to fatigue. Changes may be associated with muscle fatigue without causing it.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210000269
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  • 42
    Electronic Resource
    Electronic Resource
    Facilitation of the withdrawal reflex by repeated transcutaneous electrical stimulation: an experimental study on central integration in humans (2000)
    Springer
    European journal of applied physiology 81 (2000), S. 165-173 
    Details
    ISSN: 1439-6327
    Keywords: Key words Temporal summation ; Repeated electrical stimulation ; Experimental pain ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the present human study, we aimed to investigate the facilitation of both the subjective pain responses, and the withdrawal reflex to consecutive transcutaneous electrical stimuli as measures of temporal summation. The frequency (0.5–20 Hz) and intensity (0.4–0.8 times the reflex threshold,  ×RT) of the electrical stimuli were systematically varied. When using repeated stimulation, the stimulus intensity that evoked pain was lower than that required by a single stimulus (temporal summation). Temporal summation leading to pain was found to depend significantly upon both frequency and intensity (e.g. stimulation at 1 Hz caused summation at 0.8 × RT, whereas stimulation at 20 Hz caused summation at 0.6 × RT). The strongest reflex facilitation, and hence the strongest pain intensity was obtained for stimulation at 10–20 Hz at an intensity of 0.8 × RT. In conclusion, the results of the present human study demonstrate clearly that a stimulus that is perceived as a localised, repetitive tactile tap can be integrated and cause severe pain. This suggests that pathologically generated sparse nociceptive afferent activity causes strong pain by central integration. This might be one mechanism to explain why clinical conditions can become excruciatingly painful despite the fact that the pathophysiological changes seem to be marginal (e.g. minor nerve trauma).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050026
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    Electronic Resource
    Changes in cross-sectional area in human exercising and non-exercising skeletal muscles (2000)
    Springer
    European journal of applied physiology 81 (2000), S. 210-213 
    Details
    ISSN: 1439-6327
    Keywords: Key words Cross-sectional area ; Exercise ; Human ; Reflex sympathetic activity ; Skeletal muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This research was performed to study how the cross-sectional area (CSA) changes in the skeletal muscles of exercising (E-leg) and contralateral non-exercising (N-leg) legs and to evaluate to what extent changes in CSA mirror changes in blood flow or extravascular water displacement. Seven healthy volunteers performed plantar flexion exercise at three different exercise intensities for 10 min each. Six plantar flexions followed by a 2-s rest in between allowed repeated measurement of the blood flow to the lower limbs by duplex ultrasonography in the popliteal artery and CSA by magnetic resonance imaging. The CSA was measured using manual planimetry at rest and after 3 and 9 min of the exercise periods. The CSA increased in the E-leg by 4.5% and decreased in the N-leg by −2.4%, from rest to highest exercise intensity. Post-exercise imaging of the E-leg showed a bi-phasic recovery of CSA with a rapid phase followed by a slower phase while the blood flow very rapidly returned almost to basal. The time course of the post-exercise decrease indicated that about 50% of the increase in CSA at the highest exercise intensity might have been a result of extravascular water displacement and 50% of an increase in the vasculature volume related to the flow increase. The CSA reduction in N-leg seems to have been related to vasoconstriction, probably mainly of the capacitance vessels since blood flow was not reduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050032
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    Electronic Resource
    Muscle and tendon stiffness in patients with upper motor neuron lesion following a stroke (2000)
    Springer
    European journal of applied physiology 82 (2000), S. 275-279 
    Details
    ISSN: 1439-6327
    Keywords: Key words Eccentric-concentric actions ; Electromyography ; Gastrocnemius muscle ; Soleus muscle ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The objective of this study was to investigate muscle and tendon stiffness in the triceps surae muscles in patients who had previously had a stroke. The participants were 12 men showing slight to moderate degrees of muscle tonus in the affected leg. All patients showed minimal or no overt clinical motor symptoms, and all walked without mechanical aid. Muscle strengths in isometric and isokinetic activities were measured, as was passive resistance during plantarflexion in each leg. Walking speed was also measured. Evaluations of physical performance and muscle tone were made. Muscle and tendon stiffness was calculated from measurements whilst passively stretching during electrical stimulation, separately for each leg. Muscle strength was significantly higher in the non-affected than in the affected leg. Muscle stiffness was significantly higher in the affected leg than in the non-affected leg. Tendon stiffness was significantly higher in the non-affected than in the affected leg. The higher muscle stiffness in the affected leg might enhance the possibility for storing elastic energy during preactivation. Lower tendon stiffness in the affected leg might reduce the development of fatigue in movements at low velocities.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210000216
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    Electronic Resource
    Position sense acuity is diminished following repetitive low-intensity work to fatigue in a simulated occupational setting (2000)
    Springer
    European journal of applied physiology 81 (2000), S. 361-367 
    Details
    ISSN: 1439-6327
    Keywords: Key words Fatigue ; Glenohumeral joint ; Human ; Occupational musculoskeletal problems ; Proprioception
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Repetitive work to fatigue is soundly associated with work-related musculoskeletal disorders (WMSD), although the underlying mechanisms are poorly understood. In the present study, we tested the hypothesis that fatiguing work leads to proprioceptive deficits, which can be an initiating factor for the occurrence of WMSD. Thus, the position sense of the shoulder was determined for 13 males and 13 females before and after performing repetitive low-intensity arm work to fatigue in a simulated occupational setting. From a starting position of 45° to the sagittal plane, position sense tests consisted of subjects attempting to actively reproduce target positions of horizontal movements to 15° and 30° (shoulder adduction) and to 60° and 75° (shoulder abduction). An analysis of variance revealed that the absolute error was significantly increased following fatigue for the subjects as a group (P 〈 0.001). Furthermore, females had an overall higher error than males (P 〈 0.01). No difference in error was detected for the shorter movements versus the longer movements. However, the overall absolute error for adduction was significantly higher than for abduction (P 〈 0.001). The results of the present study support the hypothesis of diminished proprioceptive acuity following low-intensity work to fatigue. A reduction in position sense acuity could lead to impairment in motor control, which would further impact on position sense. Thus, a vicious cycle may be activated that might result in WMSD. The poorer position sense acuity observed for females may contribute to the explanation of why females demonstrate a higher incidence of WMSD than males.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004210050055
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    Electronic Resource
    Elevated levels of circulating heat shock protein 70 (Hsp70) in peripheral and renal vascular disease (2000)
    Springer
    Heart and vessels 15 (2000), S. 18-22 
    Details
    ISSN: 1615-2573
    Keywords: Key words Heat shock protein ; Antibody ; Vascular disease ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Heat shock proteins (Hsp) are families of phylogenetically conserved molecules that have a range of cytoprotective and intracellular functional roles. Reactivity to heat shock proteins has been implicated in the development of autoimmune disease and tissue expression of heat shock proteins and increased levels of anti-Hsp antibodies have also been reported in vascular disease. This study compared circulating levels of Hsp60 and Hsp70 and antihuman Hsp60, antihuman Hsp70, and antimycobacterial Hsp65 antibodies in peripheral (PVD) and renal (RVD) vascular disease with those in age- and sex-matched controls. Levels of Hsp70 were higher in both PVD (median 580 vs 40; P 〈 0.01) and RVD (median 160 vs 0; P 〈 0.03), whereas there were no differences in Hsp60 levels. Anti-Hsp60 antibody levels were elevated in PVD (146 vs 81 arbitrary units/ml; P 〈 0.04), but not RVD. This is the first study to demonstrate increased levels of circulating Hsp70 in pathological disease states; however, its physiological role remains to be determined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003800070043
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    Electronic Resource
    Effect of dietary control on plasma nitrate level and estimation of basal systemic nitric oxide production rate in humans (2000)
    Springer
    Heart and vessels 15 (2000), S. 274-279 
    Details
    ISSN: 1615-2573
    Keywords: Key words Basal systemic nitric oxide production rate ; Fasting ; Human ; Plasma nitrate ; Single-compartment model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract It is of great interest and value to evaluate the systemic nitric oxide (NO) production rate in humans under various conditions. However, the currently available estimation methods are troublesome and time-consuming. We thus aimed at developing a simple method to estimate the basal systemic NO production rate in humans based on a steady-state analysis, i.e., a balance between the systemic NO production rate and the total nitrate elimination rate. Plasma nitrate concentrations of young healthy volunteers (n = 7 in group 1; n = 9 in group 2) were measured for 2 days. In group 1, all subjects had the same meals for 7 days prior to the plasma nitrate measurement. In group 2, all subjects were allowed free diets. The plasma nitrate concentrations were highly influenced by dietary nitrite/nitrate intake in both groups and reached the steady-state levels after 14-h fasting. Accordingly, the basal systemic NO production rates were estimated from the plasma nitrate concentrations after 14-h fasting (group 1, 630 ± 37 nmol min−1 = 0.78 ± 0.03 μmol kg−1 h−1; group 2, 597 ± 45 nmol min−1 = 0.66 ± 0.05 μmol kg−1 h−1, P = not significant vs group 1). These estimated values were comparable to the values obtained by other methods. In conclusion, the present estimation method with 14-h fasting using a single-compartment analysis was found to be a simple approach to quantitative evaluation and intra- and interindividual comparisons of the basal systemic NO production rates in humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003800070005
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    Electronic Resource
    Development of human brain (2000)
    Springer
    Human evolution 15 (2000), S. 99-112 
    Details
    ISSN: 1824-310X
    Keywords: Development ; Ontogeny ; Growth ; Brain ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The human has the most complex brain of the primates group. Their development is prolonged beyond birth and it is not completed structurally nor neurochemically until age of 20 years. Decades later, degenerative phenomena begin to be evident, that little by little will drive us to death. At the end of the life, 113 grams aproximate of cerebral mass are lost. The endowment of furrows and convolutions are fixed before birth, while the cerebral surface ends up having values next to the adult at 2 years. However the cerebral weight reaches its maximum at the 20 year-old decade. A first phase of neuronal death appears during the prenatal life, which is continued by another postnatal phase, and it ends with the definitive number of neurons. However, along life, the number of neurons decreases little by little at the time of the neuroglial cells increase. Much about brain knowledge at the moment is difficult to apply to the cranial endocasts, although approaches from the MNR are hopeful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02436238
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    A Few Milestones on the Journey of Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 497-501 
    Details
    ISSN: 0935-6304
    Keywords: Historical remarks ; modern separation methods ; gas chromatography ; selective sorbents ; selectors ; discovery process ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The research conducted and the discoveries during the development of chromatography are briefly surveyed, with emphasis being placed on gas chromatography. Some actors are presented who played major roles en route from Tswett's original discovery to modern separation methods. The article is based mainly on personal memories and encounters. A few examples of the participation of our country in the development of chromatography are mentioned as well as international contacts. Some remarks are made on the use of selective sorbents or selectors in modern analytical separations. The paper closes with a few comments on the “philosophy” of the discovery process.
    Additional Material: 1 Tab.
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    Electronic Resource
    Characterization of Polydimethylsiloxanes Using an Off-Line Combination of Supercritical Fluid Chromatography with Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 502-506 
    Details
    ISSN: 0935-6304
    Keywords: Silicone oil ; supercritical fluid chromatography (SFC) ; micropacked columns ; MALDI-TOF ; GC/MS ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 4 Ill.
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    Solventless Sample Preparation Techniques in Environmental Analysis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 297-303 
    Details
    ISSN: 0935-6304
    Keywords: Sample preparation ; gas extraction techniques ; membrane-type techniques ; water analysis ; soil analysis ; gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This review focuses on the role of so-called solventless methods of sample preparation in contemporary environmental analysis. The basic classification of this group of methods as well as the principal features and advantages of the techniques in current use are discussed.
    Additional Material: 2 Ill.
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    Mixed Mode Retention and the Use of Competing Acid for the Ag+-HPLC Analysis of Underivatized Conjugated Linoleic Acids (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 317-323 
    Details
    ISSN: 0935-6304
    Keywords: Conjugated linoleic acids ; underivatized ; Ag+-HPLC ; resolution ; mixed mode retention ; hydrogen bonding ; competing acid ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Fatty acids (FAs) and fatty acid residues are generally methylated and analyzed by GC. The reasons for this are partly historic and partly because of the sensitivity advantage of flame ionization detection over UV absorption by the carboxylic acid functionality in saturated FAs. However, for strongly absorbing unsaturated acids such as the conjugated linoleic acids (CLAs), the sensitivity advantage is greatly reduced. Hence there seems little reason to waste time and introduce errors associated with methylation. Remarkably, this appears not to have been recognized. In this paper we describe our method development for the analysis of underivatized CLAs by silver ion HPLC separation on the ChromSpher Lipids column. Using mobile phases previously optimized for the analysis of the methylated CLAs, retention is excessive and a competing acid is required. Various combinations of small concentrations of acetic acid (3.0-2.5%) with acetonitrile (0.0-0.025%), respectively, yield similar resolution and run times. As well as its role as a competing acid, acetic acid acts as a general strong solvent and thus can be used alone as a modifier (without acetonitrile). However, for slightly shorter run times a mobile phase of 2.5% acetic acid and 0.025% acetonitrile was chosen as the optimum mobile phase for analysis. The separation of the free CLAs is clearly superior to those previously published and obtained in this study for the methylated CLAs. The additional specific strong interactions of the underivatized CLAs seem certain to be due to hydrogen bonding between the CLA carboxylic acid functionality and the large number of residual silanols on the surface of the silica support of the stationary phase.
    Additional Material: 6 Ill.
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    Electronic Resource
    Design, Preparation and Application of a New π-Basic Chiral Stationary Phase for the Liquid Chromatographic Separation of Enantiomers (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 333-337 
    Details
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; chiral separation ; chiral stationary phase ; separation of enantiomers ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new reciprocal π-basic chiral stationary phase (CSP) was designed based on the reciprocity conception of chiral recognition and prepared starting from (S)-leucine. The CSP thus prepared was applied in resolving various π-acidic N-(3,5-dinitrobenzoyl)-α-amino amides and esters and found to be very effective. Especially, N-(3,5-dinitrobenzoyl)-α-amino N,N-dialkyl amides were resolved very well on the new reciprocal CSP. From the chromatographic resolution results and based on the reciprocity conception of chiral recognition with the aid of Corey/Pauling/Koltan (CPK) molecular model studies, a chiral recognition mechanism which utilizes π-π interaction and simultaneously two hydrogen bonding interactions between the CSP and the analyte has been proposed. The CSP prepared in this study was also successful in resolving 3,5-dinitrophenylcarbamate derivatives of 2-hydroxycarboxylic acid esters.
    Additional Material: 4 Ill.
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    Determination of Pollutant Phenols by Capillary High-Performance Liquid Chromatography with UV Detection (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 367-372 
    Details
    ISSN: 0935-6304
    Keywords: Capillary HPLC ; gradient elution ; temperature programming ; phenolic compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This paper describes a liquid chromatographic method using a reversed phase capillary column coupled to an UV detector for the quantitation of thirteen pollutant phenols. Chromatographic separation was carried out with gradient elution at 25.0 ± 0.1°C. The two major anisocratic elution modes (gradient elution and temperature programming) were evaluated. The detection limit range was 10-81 pg (100 nL injected). The chromatographic method combined with liquid-liquid extraction was applied to analysis of these compounds in river water. Recoveries of 75-103% were achieved for most of them.
    Additional Material: 5 Ill.
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    Use of Capillary Supercritical Fluid Chromatography in the Analysis of Zinc Dialkyldithiophosphates (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 389-392 
    Details
    ISSN: 0935-6304
    Keywords: Capillary SFC ; zinc dialkyldithiophosphates ; lubricating oils ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 5 Ill.
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  • 56
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    Regenerable MnO-based Glass Absorber Tube with Press-Fit Connection for Easy Post-Injector Evaluation of Carrier Gases Oxygen Contamination (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 688-692 
    Details
    ISSN: 0935-6304
    Keywords: Solid oxygen scavenger ; carrier gas purity ; manganous oxide ; glass press-fit connections ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 6 Ill.
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    Detection of Polyols by HPLC Coupled with an On-Line Photochemical Oxidation Reactor and Chemiluminescence Detection (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 127-130 
    Details
    ISSN: 0935-6304
    Keywords: Chemiluminescence ; diol compound ; oxalate ; post-column reaction ; ruthenium complex ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---In this paper we propose a new post-column detection method for polyols containing 1,2-diol, 1,3-diol, and saccharides. The polyols are oxidized in a photochemical reactor to yield oxalate with subsequent chemiluminescence detection using [Ru(III)(bpy)3]3+. A mixing solution of eluate and oxidizing reagent is delivered to a reaction coil, which is then irradiated with ultraviolet light to promote the oxidation reaction. The detection limits for 1,2-ethanediol (ethylene glycol) and 1,3-propanediol were 38 pmol and 23 pmol, respectively.
    Additional Material: 5 Ill.
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    Monolithic Silica Columns for HPLC, Micro-HPLC, and CEC (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 111-116 
    Details
    ISSN: 0935-6304
    Keywords: Monolithic column ; silica monolith ; HPLC ; capillary liquid chromatography ; capillary electrochromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Two types of monolithic silica columns derivatized to form an ODS phase, one prepared in a fused silica capillary (SR-FS) and the other prepared in a mold and clad with an engineering plastic (poly-ether-ether-ketone) (SR-PEEK), were evaluated. The column efficiency and pressure drop were compared with those of a column packed with 5-μm ODS-silica particles and of an ODS-silica monolith prepared in a mold and wrapped with PTFE tubing (SR-PTFE). SR-FS gave a lower pressure drop than a column packed with 5-μm particles by a factor of 20, and a plate height of 20 μm at a linear velocity below 1 mm/s. SR-PEEK showed higher flow-resistance than the other monolithic silica columns, but they still showed a minimum plate height of 8-10 μm and a lower pressure drop than popular commercial columns packed with 5-μm particles. The evaluation of SR-FS columns in a CEC mode showed much higher efficiency than in a pressure-driven mode.
    Additional Material: 6 Ill.
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  • 59
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    Coupled LC-GC-NPD for Determination of Carbazole-Type PANH and Its Application to Personal Exposure Measurement (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 131-137 
    Details
    ISSN: 0935-6304
    Keywords: On-line coupled LC-GC ; nitrogen selective detection ; NPD ; carbazoles ; PANH ; personal exposure measurement ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A coupled LC-GC method for the analysis of carbazole-type PANH has been developed and evaluated. Group separation and isolation of carbazoles from interfering acridines in a complex sample matrix was accomplished by using a back-flush technique and an in situ end-capped dimethylaminopropyl silica column in the HPLC part of the system. On-line injection of the carbazole fraction into the GC column was performed with a loop-type interface utilizing concurrent solvent evaporation technique. An LOD of 1-3 pg of individual carbazole compounds was achieved by nitrogen selective detection using an NPD. The method is shown to be robust and is demonstrated by application to personal exposure measurement in an aluminum reduction plant.
    Additional Material: 4 Ill.
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  • 60
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    Fast Separation of Nucleosides by Capillary Electrochromatography on Non-Endcapped Phenyl-Bonded Silica Phase Using Short-End Injection Method (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 138-142 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrochromatography ; nucleosides ; short-end injection ; phenyl-bonded silica ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The influence of several experimental parameters (pH, ionic strength, organic modifier content of hydro-organic buffer) upon EOF, migration time, and retention factor has been studied in CEC with a phenyl-bonded silica column on a model mixture of five nucleosides. This paper illustrates the current interest in CEC as a method of resolving complex mixtures of neutral and ionic solutes and demonstrates the potential of the short-end injection method as a means of reducing analysis time.
    Additional Material: 4 Ill.
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  • 61
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    Capillary Gas Chromatography of Trichlorophenols Using Ammonia as Carrier Gas (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 156-157 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; trichlorophenols ; ammonia ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 1 Tab.
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  • 62
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    Comparison of Three Sorbents for Clean-Up of Mixed Aliphatic Hydrocarbons, PCBs, and PCTs Prior to Simultaneous Determination by GC-ECD/FID (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 401-404 
    Details
    ISSN: 0935-6304
    Keywords: Clean-up ; aliphatic hydrocarbons ; organochlorine compounds ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 2 Ill.
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  • 63
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    Simultaneous Speciation Analysis of Fe(II) and Fe(III) in Mineral Samples by Using Capillary Electrophoresis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 430-436 
    Details
    ISSN: 0935-6304
    Keywords: Speciation ; digestion ; capillary electrophoresis ; ferrous ; ferric ; mineral analysis ; complexation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Capillary electrophoresis is used as a means of cation separation for cationic speciation analysis. Acceptable separation of ferrous and ferric iron was achieved by using a mixed complexing agent run buffer which gave stable species in solution. These iron species, and total iron, were determined simultaneously in certified reference materials with a single digestion step. A variety of digestion techniques were compared, primarily for their non-oxidative capabilities in order to preserve the oxidation state of iron in the mineral samples. The most favorable recoveries resulted from a continuous flow nitrogen purge technique. Total iron levels obtained from the CE method were compared with those determined by two spectroscopic techniques, with similar results obtained using the different instrumental methods.
    Additional Material: 3 Ill.
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  • 64
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    Temperature-Programmed Packed Capillary Liquid Chromatography Coupled to Fourier-Transform Infrared Spectroscopy (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 525-530 
    Details
    ISSN: 0935-6304
    Keywords: Packed capillary liquid chromatography ; temperature programming ; Fourier-transform infrared spectroscopy ; polymer additives ; pneumatic nebulization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Temperature-programmed packed capillary liquid chromatography has been coupled off-line to Fourier-transform infrared spectroscopy, utilizing a commercially available interface with a pneumatic nebulizer rebuilt to handle low flow rates at elevated temperatures. The modified interface showed excellent performance with regard to non-aqueous reversed phase separations of polymer additives, resulting in constructed Gram-Schmidt chromatograms comparable to chromatograms obtained using UV detection. The spray of the in-house constructed nebulizer was not influenced by temperature changes of the column effluent, and hence temperature-programmed gradient separations could be used successfully. The relative standard deviation of peak height was 4.4% (n = 5) and the mass limit of detection was determined to be about 40 ng, using a polymer antioxidant as model compound. The present instrumental coupling has been used for characterization of the antioxidant Irgafos P-EPQ.
    Additional Material: 5 Ill.
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  • 65
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    Microfabricated Monolith Columns for Liquid Chromatography. Sculpting Supports for Liquid Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 19-26 
    Details
    ISSN: 0935-6304
    Keywords: Microfabrication ; monolith ; electrochromatography ; peptides ; reactive ion etching ; reversed phase ; nanocolumns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monolith columns are generally fabricated by polymerization of monomers within a column. This paper reviews an alternative strategy in which the bed is microfabricated in an inorganic material by ablation. Channels of 1.5 μm width and 10 μm depth were sculpted in quartz by deep reaction ion etching. Using this approach chromatographic beds were constructed in which cubic support structures were created and arranged in rows to mimic particles in a conventional column. Beds ranging from hundreds of thousands to millions of “particles” with volumes of 15 nL to 15 μL were produced. Columns that had been derivatized with an octadecyl silane stationary phase were used to separate both low molecular weight analytes and peptides in the CEC mode. Plate height in the CEC mode was 1.2 μm at maximum efficiency.
    Additional Material: 9 Ill.
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  • 66
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    Miniaturized Molecularly Imprinted Continuous Polymer Rods (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 44-46 
    Details
    ISSN: 0935-6304
    Keywords: In situ molecular imprinting ; continuous polymer rod ; miniaturized column ; chiral recognition ; diastereoselectivity ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Molecularly imprinted continuous polymer rods are prepared inside PEEK tubes of 1 mm i. d. by an in situ preparation technique; and chiral separations on such media have been demonstrated. The miniaturized column filled with (-)-cinchonidine-imprinted or (+)-cinchonine-imprinted polymer rods based on a copolymer of 2-(trifluoromethyl)acrylic acid and ethylene glycol dimethacrylate permitted diastereoseparation of (-)-cinchonidine and (+)-cinchonine; the template molecule is retained to a greater extent than the corresponding antipode. Increasing the amount of cyclohexanol in the polymerization mixture decreased the backpressure of the resultant rod and the addition of latex beads suspended in water to the prepolymerization mixture affected the selectivity and affinity of the imprinted polymer rods. The column length is adjusted easily by cutting, thus allowing easy control of retention behavior and analysis time.
    Additional Material: 1 Ill.
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  • 67
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    Affinity Chromatography of Human Blood Coagulation Factor VIII on Monoliths with Peptides from a Combinatorial Library (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 47-58 
    Details
    ISSN: 0935-6304
    Keywords: Monolith ; factor VIII ; affinity chromatography ; combinatorial peptide library ; peptide synthesis ; recombinant proteins ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: FVIII is a very complex molecule of great therapeutic significance. It is purified by a sequence of chromatographic steps including immunoaffinity chromatography. A peptide affinity chromatography method has been developed using peptides derived from a combinatorial library. Spot technology using cellulose sheets has been applied for this purpose. The dual positional scanning strategy was used for identification of the amino acids in random positions. Approximately 5000 possible candidates found in the first screening round were reduced to a panel of 36. Six candidates have been selected empirically. Five peptides seem to be directed against the light chain of FVIII, one peptide seems to be directed against the heavy chain. The peptides have been immobilized on conventional beaded material and CIM polymethacrylate monoliths. Much better performance with respect to capacity and selectivity has been observed with the monolithic material. Exposure of the ligand and its ensuing accessibility are responsible for these properties.
    Additional Material: 8 Ill.
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  • 68
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    Capillary Electrochromatography with Monolithic Poly(styrene-co-divinylbenzene-co-methacrylic acid) as the Stationary Phase (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 67-72 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrochromatography ; monolithic column ; electroosmotic flow ; retention mechanism ; aromatic compound ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new kind of monolithic capillary electrochromatography column with poly(styrene-co-divinylbenzene-co-methacrylic acid) as the stationary phase has been developed. The stationary phase was found to be porous by scanning electron microscopy and the composition of the continuous bed was proved by IR spectroscopy to be the ternary polymer of styrene, divinylbenzene, and methacrylic acid. The effects of operating parameters, such as voltage, electrolyte, and organic modifier concentration in the mobile phase on electroosmotic flow were studied systematically. The retention mechanism of neutral solutes on such a column proved to be similar to that of reversed-phase high performance liquid chromatography. In addition, fast analyses of phenols, chlorobenzenes, anilines, isomeric compounds of phenylenediamine and alkylbenzenes within 4.5 min were achieved.
    Additional Material: 9 Ill.
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  • 69
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    Particle Loaded Monolithic Sol-Gel Columns for Capillary Electrochromatography: A New Dimension for High Performance Liquid Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 81-88 
    Details
    ISSN: 0935-6304
    Keywords: Monolithic chromatography columns ; capillary electrochromatography (CEC) ; micro high performance liquid chromatography ; sol-gel based columns for chromatography ; fritless capillary chromatography columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Particle-loaded (3 μm, octadecylsilica) monolithic sol-gel columns have been prepared and selected characteristics measured. Several electrical properties may be calculated from simple current measurements in the column as a whole. Resistivity in the packed segment is approximately three times that in open segments, resulting in a 60% increase in field strength in the packed regions compared to the capillary with no packing. The surprisingly high specific permeability of these sol-gel columns is characteristic of 8-μm particles, which allows their operation in the microLC mode at pressures as low as 69 kPa where their efficiency is about 50,000 plates per meter and in the CEC mode where efficiency is about 106,000 plates per meter at 5 kV. There is a relatively rapid loss of efficiency with increasing linear velocity beyond 0.2 mm/s in microLC mode, which may be due to additional diffusion processes in the inter-particulate voids. A rapid loss of efficiency above 0.5 mm/s is also observed in the CEC mode, for the same reasons. Chromatographic retention behavior in either separation mode is characteristic of conventional octadecylsilica particles, indicating that analytes have significant access to the surface within the pores of the immobilized bonded phase.
    Additional Material: 6 Ill.
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  • 70
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    Tailoring Mesopores in Monolithic Macroporous Silica for HPLC (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 106-110 
    Details
    ISSN: 0935-6304
    Keywords: Silica ; monolithic column ; aging ; mesopores ; pore size distribution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Mesopore formation in silica gels having continuous macropores has been investigated. The macroporous wet silica gel prepared by the sol-gel process including phase separation was aged in a basic solvent making use of hydrolysis of urea in a closed condition. The mesopore structure was finally obtained by subsequent evaporation drying of solvent and heat-treatment at 600°C for 2 h. The dissolution-reprecipitation kinetics at the interfaces between wet gel skeletons and an external solvent affected the size and volume of pores formed within the skeletons. Below 120°C, mesopores suitable for various chromatographic applications have been formed typically within 24 h. On the other hand, at 200°C, the pore size attained the macropore dimensions (〉50 nm), and the whole macroporous morphology was significantly modified.
    Additional Material: 7 Ill.
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    Separation of Anthraquinones by Capillary Electrophoresis and High-Performance Liquid Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 143-148 
    Details
    ISSN: 0935-6304
    Keywords: Analysis of anthraquinones ; capillary electrophoresis ; high-performance liquid chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The separation and determination of twelve anthraquinones, viz. anthraquinone 1, chrysphanol 2, aloe-emodin 3, alizarin 4, anthraquinone-2-carboxylic acid 5, purpurin 6, sennoside B 7, sennoside A 8, emodin 9, quinalizarin 10, rhein 11, and anthraflavic acid 12, were achieved by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Detection at 260 nm with a buffer solution containing 30 mM sodium borate (adjusted to pH = 10.56 with 0.05N NaOH) and acetonitrile (9 : 1) in CE or with a linear gradient elution containing 20 mM KH2PO4 with 0.05% phosphoric acid (pH = 2.91) and methanol in HPLC was found to be the most suitable approach for this separation. Contents of six components (2, 3, 7, 8, 9, 11) in crude Rhei Rhizoma extract could easily be determined within 39 min by CE or 63 min by HPLC. The effects of buffers on this separation and the validation of the two methods were studied.
    Additional Material: 5 Ill.
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    Two-Dimensional Gas Chromatography. Concepts, Instrumentation, and Applications - Part 2: Comprehensive Two-Dimensional Gas Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 167-181 
    Details
    ISSN: 0935-6304
    Keywords: Comprehensive two-dimensional GC ; GC×GC ; orthogonal chromatography ; GC/MS ; group type separations ; PCBs ; petroleum ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The writer of this review published in 1978 a three-part article on two-dimensional gas chromatography in the first three issues of this journal [1]. The review was written at a time when capillary column GC was still in its infancy. Commercial columns were (essentially) unavailable and sample introduction into capillary columns was done exclusively in the split mode. Two-dimensional separations were explored in only a few laboratories. The limitations of capillary column technology made this exercise rather difficult. The introduction of fused silica capillary columns in the early eighties drastically changed the landscape in which gas chromatography was practiced. It took the chromatographic community just a few years to convert from packed columns to capillary columns. Instrumentation and accessories specifically designed for capillary column use came onto the market. This writer had great hopes that the revolution in capillary column GC would be mirrored in the development of instrumentation for Two-Dimensional Gas Chromatography. This never materialized. On the contrary, tentative steps taken by a few manufacturers and suppliers of chromatographic equipment fizzled out. It was perhaps the introduction of relatively inexpensive and user friendly GC/MS instrumentation, in combination with nearly indestructible fused silica capillary columns that took away the incentive to develop commercially viable Two-Dimensional Gas Chromatography. Much of the thinking went like this: why insist on good chromatography if mass spectrometry can do the job without the need of complete separation. Some progress in the further development of conventional Two-Dimensional Gas Chromatography has certainly been made over the last 20 years but there has not been a great deal of excitement. Applications have also been relatively sparse and they are limited to just a few areas. Science does not remain static and chromatography is no exception. Progress in gas chromatography is driven by new technology and ideas. Substantial improvements in two-dimensional GC were not forthcoming until Phillips and his research group introduced and implemented an entirely new form of Two-Dimensional Gas Chromatography, called comprehensive GC×GC. This breakthrough occurred only in 1991 [2]. It does take some time before scientists change attitudes and habits. There is always a time lag between the introduction of new technology and its general acceptance. The public's attitude toward comprehensive Two-Dimensional Gas Chromatography is probably no exception. The number of scientists who are actively pursuing this new branch of gas chromatography is still very small. It is often a single individual who carries the torch. J.B. Phillips' name is synonymous with comprehensive Two-Dimensional Gas Chromatography. He is not only its inventor and proponent but his fertile mind has initiated research in other related areas. Sadly, he passed aware shortly before this review was written. This contribution is dedicated to his memory.
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    A Simple Way to Speed up Separations by GC-MS Using Short 0.53 mm Columns and Vacuum Outlet Conditions (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 677-680 
    Details
    ISSN: 0935-6304
    Keywords: Capillary ; fast separations ; mass spectrometry ; vacuum ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---There is a constant drive to speed up GC separations. Shorter analysis times provide more analyses per day, which reduces cost. One approach is to reduce column length and column diameter and columns of 0.15 mm i.d. have indeed grown in popularity. However, the majority of applications are still done with 0.25 mm and 0.32 mm columns.
    Additional Material: 10 Ill.
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  • 74
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    Identification and Determination of Active Components in Gentiana rigescens Franch by Micellar Electrokinetic Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 697-698 
    Details
    ISSN: 0935-6304
    Keywords: Gentiana rigescens Franch ; gentiopicroside ; swertiamarin ; MEKC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 2 Ill.
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  • 75
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    Applications of PTV Injectors for Problem Solving in the Petrochemical Industry. Thermal Desorption with GC and GC-MS (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 479-484 
    Details
    ISSN: 0935-6304
    Keywords: Programmable temperature vaporizing injection (PTV) ; thermal desorption ; gas chromatography ; mass spectrometry ; plasticizers ; polyethylene ; food wrapping film ; explosive powders ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Programmable Temperature Vaporizing Injection (PTV) has been used extensively as a means of injecting large volumes of samples to enhance sensitivity. This paper describes the use of PTV injection in the desorption mode for the analysis of a range of solid samples, and four examples of this application are described in detail. Detection by mass spectrometry was used extensively as a means of identification of the components in the various samples which were characterized.
    Additional Material: 12 Ill.
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    Effects of Injected Volume and Applied Voltage on Column Efficiency in Capillary Electrochromatography with Open Tubular Columns of 10 μm i. d. (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 373-378 
    Details
    ISSN: 0935-6304
    Keywords: Open tubular columns ; capillary electrochromatography ; column efficiency ; injected volume ; applied voltage ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of some instrumental parameters on column efficiency in open tubular capillary electrochromatography (OTCEC) has been evaluated. First, it was investigated whether band broadening due to the sample injection process is within a tolerable range when an open tubular column (OTC) of about 10 μm i. d. is used. As a result of the small injection profile factor (K2 = 1.3), injected volumes must be sufficiently small (less than 10 pL) to avoid a significant efficiency loss (〉5%) when hydrodynamic injection by siphoning is employed. Secondly, the kinetic performance of OTCs in a CEC system was estimated from the variation of the reduced plate height (h) with the reduced linear velocity (ν) which was controlled by the voltage applied. Reasonable agreement was obtained between the theoretical h versus ν curve and the experimental values for a group of polycyclic aromatic hydrocarbons used as test compounds. Values of 0.25 for minimum h at an optimum ν of 16 are estimated, which permit separations with around 400,000 plates per meter to be obtained in less than 5 min. Finally, the possibility of estimating the diffusion coefficients of the solutes in the mobile phase from the plot of the height of a theoretical plate versus electroosmotic flow velocity is shown.
    Additional Material: 5 Ill.
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    Application of Supercritical Fluid Chromatography to the Analysis of Waxes in Objects of Art (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 393-396 
    Details
    ISSN: 0935-6304
    Keywords: Supercritical fluid chromatography (SFC) ; micropacked capillary columns ; waxes ; restoring ; objects of art ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 2 Ill.
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  • 78
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    System Peaks of Cyclodextrins in Capillary Electrophoresis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 409-412 
    Details
    ISSN: 0935-6304
    Keywords: Cyclodextrin ; capillary electrophoresis ; system peak ; CHES 1 ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using a running buffer containing cyclodextrins (CDs) and 2-[N-cyclohexylamino]-ethanesulfonic acid (CHES), positive system peaks were observed in the analysis of a ganglioside mixture by CE-UV. These system peaks were related to CDs in the running buffer because these peaks were also detected when a plug of solution devoid of CDs but having the same CHES concentration and pH as the running buffer was injected. Neutral CDs were separated owing to the formation of inclusion complexes with the anionic CHES ion. One possible explanation for the positive system peaks is that the anionic CD-CHES inclusion complex is displaced by co-ions with higher UV absorptivity.
    Additional Material: 3 Ill.
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  • 79
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    Retention Prediction System of O-Aryl,O-(1-methylthioethylidene-amino)phosphates on RP-HPLC (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 445-448 
    Details
    ISSN: 0935-6304
    Keywords: O-Aryl,O-(1-methylthioethylideneamino)phosphates ; retention prediction ; quantitative structure-retention relationship (QSRR) ; reversed-phase HPLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Using factor analysis and stepwise linear regression methods, two parameters - CMR and ECCR - were selected from eight solute-related structure parameters as the most retention-influencing parameters. The relationships between the retention data (k ´) and the two structure parameters were established for 13 O-aryl,O-(1-methylthioethylideneamino)phosphate compounds under a wide range of experimental conditions. The retention data (k ´) of another seven compounds with similar structures were predicted using these QSRR equations. Good agreement was obtained between the experimental k ´ values and predicted ones.
    Additional Material: 1 Ill.
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  • 80
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    Optimization of a GC-MS/MS Method for the Analysis of PCDDs and PCDFs in Human and Fish Tissue (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 595-599 
    Details
    ISSN: 0935-6304
    Keywords: GC-MS/MS ; PCDDs ; PCDFs ; human tissue ; fish tissue ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This paper outlines the possibilities of selectivity and sensitivity enhancement in measuring PCDD/F congeners using an ion trap GC-MS/MS. The pressure of the collision gas and the collision energy were optimized. The modified GC-MS/MS method was applied to the determination of PCDDs and PCDFs in human and fish tissues. Limits of quantification were about 1 pg/g of fat for all seventeen 2378 PCDD/Fs tested (starting amount of fat, 2 g).
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  • 81
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    Determination of Lucidin in Rubia tinctorum Aglycones by an HPLC Method with Isocratic Elution (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 600-602 
    Details
    ISSN: 0935-6304
    Keywords: HPLC separation ; lucidin ; Rubia tinctorum ; anthraquinones ; isocratic elution ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---An HPLC method has been developed for the separation of anthraquinones with particular attention to the determination of lucidin in commercially available sources of Rubia tinctorum aglycones. Variations of chromatographic conditions have been studied in order to provide suitable resolution of anthraquinones under isocratic conditions on an end-capped RP C18-column.
    Additional Material: 2 Ill.
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  • 82
    Electronic Resource
    Electronic Resource
    Optimization and Validation of a Fast Liquid Gradient for Determination of Prominent Flavan-3-ols and Flavonols in Fresh Vegetables (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 637-643 
    Details
    ISSN: 0935-6304
    Keywords: HPLC ; fast separation ; flavan-3-ol ; flavonols ; vegetables ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A fast high-performance liquid chromatography method was used for analysis of prominent flavan-3-ols and flavonols in vegetables. Gradient elution with phosphoric acid-acetonitrile mixtures and phosphoric acid-methanol mixtures allowed fast and complete separation of the studied phenolic compounds within analysis times less than 10 min. The development of two elution gradients using methanol and acetonitrile as modifiers proved to be an excellent approach for the verification of the real polyphenolic composition in vegetables samples because the two optimized methods allowed the separation of the same number of compounds in the same elution order. Diode-array detection was employed for the provisional identification of phenolic compounds that were not available as standards. We preferred methanol as a modifier because it was less toxic and cheaper than acetonitrile. Detection limits ranged between 0.12 and 0.59 μg mL-1. High recoveries of phenolics from fresh vegetables were measured in all studied cases, independent of the phenolic structure, matrix, and vegetable in question. High levels of procyanidins between 150 and 450 mg kg-1 were found in all studied vegetables. Quantification of quercetin and kaempferol glycosides was only possible in marrow and onion, respectively.
    Additional Material: 3 Ill.
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  • 83
    Electronic Resource
    Electronic Resource
    Gas Chromatographic Enantiomer Separation of Atropisomeric PCBs Using Modified Cyclodextrins as Chiral Phases (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 619-627 
    Details
    ISSN: 0935-6304
    Keywords: Enantiomer separation ; mixed chiral selectors ; modified cyclodextrins ; gas chromatography ; PCB ; o,p´-DDD ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Columns containing different types of cyclodextrin derivatives have been evaluated for chiral gas chromatographic separation of atropisomeric PCBs, o,p´-DDT and o,p´-DDD. Separation was attempted on columns containing mixed chiral selectors, and the performance of two closely related selectors was also examined. The cyclodextrins were: permethylated-β-CD (PM-β-CD), heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-CD (2,3-M-6-TBDMS-β-CD), heptakis(2,3-di-O-methyl-6-O-tert-hexyldimethylsilyl)-β-CD (2,3-M-6-THDMS-β-CD), and heptakis(2,3-di-O-ethyl-6-O-tert-hexyldimethylsilyl)-β-cyclodextrin (2,3-E-6-THDMS-β-CD). The cyclodextrins were dissolved in OV-1701 or in a dimethylsiloxane/silarylene copolymer containing 5% phenyl in the backbone. The application of mixed chiral selectors led to improved separations, however; at most eleven PCB congeners were separated on a single column. Chiral resolution of o,p´-DDD was achieved. The use of a dimethylsiloxane/silarylene copolymer as a matrix for the cyclodextrins is a promising approach. With such a matrix, blocking of the CD cavities by silicone substituent groups can be avoided, and a reasonable CD solubility can be provided. The selectivity of heptakis(2,3-di-O-ethyl-6-O-tert-hexyldimethylsilyl)-β-CD and heptakis(2,3-di-O-methyl-6-O-tert-hexyldimethylsilyl)-β-CD was quite different, the former selector could separate four congeners, while the latter separated ten congeners.
    Additional Material: 5 Ill.
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  • 84
    Electronic Resource
    Electronic Resource
    Simultaneous Determination of Organic Acids in Wine Samples by Capillary Electrophoresis and UV Detection: Optimization with Five Different Background Electrolytes (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 647-652 
    Details
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; UV detection ; organic acids ; background electrolyte optimization ; wine ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A simple technique is described for the routine capillary electrophoretic determination of organic acids in wine samples. Several aromatic and non-aromatic compounds, including phthalic acid, benzoic acid, sorbic acid, boric acid, and phosphate, were evaluated as background electrolytes in order to obtain the highest resolution and detection sensivity. Factors that affect capillary electrophoretic separation such as the concentration and pH of the background electrolyte (BGE), the concentration of the electroosmotic flow modifier (EOF), and methanol addition to the electrolyte were investigated systematically. Tartaric, malic, succinic, acetic, and lactic acids were determined simultaneously in approximately six minutes using an electrolyte containing 3 mM phosphate and 0.5 mM myristyltrimethylammonium bromide (MTAB) as electroosmotic flow modifier at pH 6.5. This method is quantitative, with recoveries in the 90-102% range and linear up to 50 mg L-1. The precision is better than 1% and the procedure shows the appropriate sensibility, with detection limits between 0.015 and 0.054 mg L-1. The proposed method was successfully employed for the determination of organic acids in wine samples by direct sample injection after appropriate dilution and filtration.
    Additional Material: 5 Ill.
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  • 85
    Electronic Resource
    Electronic Resource
    Optimization of Focused Microwave-Assisted Extraction of DDT and Derivatives from Soil Samples (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 681-687 
    Details
    ISSN: 0935-6304
    Keywords: Focused microwave assisted extraction ; close microwave-assisted extraction ; DDT ; soil samples ; experimental design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Optimization of focused microwave (FMW)-assisted extraction of 4,4′-DDE, 4,4′-DDD, and 4,4′-DDT from soil samples was carried out using central composite designs. All the extracts were analyzed with GC/MS and some of them also with GC/AED using columns of different polarities for each of the techniques. The extraction of the analytes was carried out in two ways: with acetic acid as microwave radiation absorbent solvent and n-decane to concentrate the analytes and with reagent water and iso-octane as solvents. In the first case, the influence of the extraction temperature, the extraction time, and the addition of sodium chloride were studied and the optimum conditions for the extraction of 1 g of soil with 5 mL of acetic acid and 2 mL of n-decane were 1.30 mol L-1 sodium chloride at 98°C for 9.3 min. In the second case, the temperature was kept constant (94°C) and the influence of the concentration of sodium chloride and the extraction time were studied. The optimum conditions were 5 mL of a 2.0 mol L-1 sodium chloride together with 2 mL of iso-octane for 15 min. The recoveries obtained by water-FMW extraction were significantly lower than those obtained by the acetic acid-FMW procedure. These last recoveries were in good agreement with those obtained by closed microwave assisted-extraction with acetone-n-hexane as solvent.
    Additional Material: 3 Ill.
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  • 86
    Electronic Resource
    Electronic Resource
    Identification and Quantification of Thiaarenes in the Flue Gas of Lignite-Fired Domestic Heating (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 457-473 
    Details
    ISSN: 0935-6304
    Keywords: Domestic lignite heating emissions ; isokinetic sampling ; polyaromatic sulfur heterocycles (PASH) ; thiaarenes ; atomic emission detection (AED) ; pulsed flame photometric detection (PFPD) ; high resolution mass spectrometry (HRMS) ; retention indices ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Lignite briquettes with different sulfur contents were burned in a common type of domestic heating system. The levels of polycyclic aromatic sulfur heterocycles (PASH, thiaarenes) and their alkylated and phenylated derivatives in the flue gas were determined. The analytical method described comprises isokinetic sampling, GC/full scan-MS for screening analysis, HPLC/wavelength programmable fluorescence detection (selected PAHs used as internal standards for GC), GC/atomic emission detection or GC/pulsed flame photometric detection (sulfur-selective detection of thiaarenes), GC/high resolution MS (verification and quantification of thiaarenes), and the determination of the gas chromatographic retention indices. In total 57 thiaarene species (individual compounds if possible and groups of isomeric compounds such as alkylated/phenylated species) were identified, their retention indices determined, and quantified as flue gas emission concentrations. Not only thiophene-related thiaarenes but also species with two sulfur atoms in the molecule (e. g. thienothiophene derivatives) were found. The thiaarene emission pattern is discussed, as is the correlation between the thiaarene emissions and the sulfur content of the different briquette types burned.
    Additional Material: 11 Ill.
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  • 87
    Electronic Resource
    Electronic Resource
    Advances in Flavor Research (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 489-496 
    Details
    ISSN: 0935-6304
    Keywords: Flavor ; odorant ; headspace ; GC ; interaction ; electronic nose ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---In order to understand the flavor of foods a multitude of scientific investigations have been carried out and a number of analytical tools for flavor research developed in the last few decades. Initially, scientific investigations focused mainly on the identification of all compounds that could contribute to the flavor. Olfactory GC techniques permitted the division of identified volatiles into odor-active and non-odor-active. Many techniques were developed to enhance the quality and the information content of the flavor results. Since the early 1990s, analytical investigations have dealt with interactions between food matrices and flavor compounds and the human influence on the retardation of odorants. New analytical methods concentrate on the headspace of the sample by using static or dynamic headspace analysis, or deal with measurements of volatile release in the mouth by a novel nose sampler and oral vapor GC. These useful tools clarify the effects of breathing, chewing, and saliva flow on flavor release. Though the human nose performs well at low concentrations of odorants, it is a medium-term aim to replace the use of the human nose by analytical techniques. Future investigations will probably deal with the interactions of odorants and the human receptors and it is mainly these receptors that will play a key role in aroma research. By analysis of the effects of odorants on the receptors the mechanisms of odor perception will be elucidated. This will enable the development of supporting analytical tools like electronic noses that really do function as noses, or “neural networks”.
    Additional Material: 9 Ill.
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  • 88
    Electronic Resource
    Electronic Resource
    Modelling analysis of human optic nerve fibre excitation based on experimental data (2000)
    Springer
    Medical & biological engineering & computing 38 (2000), S. 454-464 
    Details
    ISSN: 1741-0444
    Keywords: Optic nerve ; Human ; Self-sizing spiral cuff electrode ; Finite elements method ; Fibre model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The aim of the study is to determine which of the existing myelinated mammalian nerve fibre models better fits experimental data resulting from electrical stimulation of the human optic nerve and from propagation velocity measured on primates. The macroscopic electric potential is computed in a 3D, inhomogeneous and anisotropic nerve model. The Chiu-Sweeney (CS) and the Schwarz-Wesselink (SW) membrane descriptions are then considered. Variations in parameters that are not well established (encapsulation-tissue thickness, nerve-fascicle conductivity, geometric and electrochemical fibre cable parameters) are taken into account. Results demonstrate that the SW model predictions are in better agreement with the experimental data than those of the CS model, although thresholds are still too high. When channel densities are varied, the SW model turns out to be more robust than the CS model. For a suitable leakage channel density value (about 8% of the original one), the SW model predicts a conduction velocity of 11.4ms−1 and an excitation threshold of 0.055 mA (for 0.1 ms pulse duration), which is in very good agreement with experimental values (11 ms−1 and 0.055 mA). Potassium current in the SW model is necessary for stability. Introduction of a potassium-like current can restore stability in the CS system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02345016
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  • 89
    Electronic Resource
    Electronic Resource
    Comprehensive Two-Dimensional Gas Chromatography with a Rotating Thermal Desorption Modulator and Independently Temperature-Programmable Columns (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 189-196 
    Details
    ISSN: 0935-6304
    Keywords: Comprehensive two-dimensional gas chromatography ; thermal desorption modulator ; temperature programming ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---In comprehensive two-dimensional gas chromatography, two individual separations are coupled by means of a rotating thermal desorption modulator interface. The injection pulse introduced via the interface onto the second column should be as short as possible. Parameters affecting the modulator operation are studied. In the set-up used in this study, the temperature of the second column can be programmed independently from that of the first column. Optimization of the second-dimension separation to minimize peak broadening and maximize resolution is discussed and an elegant approach to determine second-dimension retention times using a non-constant modulation frequency is demonstrated. The high separation power of the comprehensive system is demonstrated by the analysis of technical and biota samples containing chlorinated biphenyls and toxaphene.
    Additional Material: 7 Ill.
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  • 90
    Electronic Resource
    Electronic Resource
    Is Multidimensional High Performance Liquid Chromatography (HPLC) an Alternative in Protein Analysis to 2D Gel Electrophoresis? (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 259-265 
    Details
    ISSN: 0935-6304
    Keywords: Proteomics ; protein analysis ; multidimensional HPLC ; ion-exchange chromatography ; reversed phase chromatography ; comprehensive HPLC ; two-dimensional HPLC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The interactive modes of High Performance Liquid Chromatography (HPLC) of proteins provide a platform for the construction of a multidimensional HPLC system coupled to mass spectrometry. We present a system composed of both anion and cation exchanger columns, in the first dimension, and n-octadecyl bonded 1.5 μm nonporous silica columns in the second dimension. Both columns are operated under gradient conditions. A system suitability test with standard proteins showed that the total analysis can be performed within about 20 minutes. The fractions taken from the ion exchanger column are directly analyzed within one minute on the reversed phase column at a high flow rate. Two reversed phase columns are applied and operated alternatively: while the first column performs the separation within one minute, the analytes leaving the first dimension are enriched in an on-column focusing mode on top of the second column. The sample clean-up and enrichment is performed on a novel type of restricted access cation exchanger column with internal sulfonic acid groups and external diol groups. The columns exhibit a molecular weight exclusion limit for globular proteins of about 15 kDa. Our next studies will be directed towards the analysis of proteins and peptides from extracts of fibroblasts.
    Additional Material: 4 Ill.
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  • 91
    Electronic Resource
    Electronic Resource
    Reversed-Phase High-Performance Liquid Chromatographic Separation and Determination of 4-Amino-azobenzene-4′,5-disulfonic Acid and Related Products in Industrial Wastewater Effluents (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 329-332 
    Details
    ISSN: 0935-6304
    Keywords: HPLC ; industrial wastewater ; process development ; 4-amino-azobenzene-4′,5-disulfonic acid (AABDS) ; 4-amino-azobenzene (AAB) ; 4-amino-azobenzene-4′-sulfonic acid (AABS) ; 4-amino-azobenzene-4′,3,5-trisulfonic acid (AABTS) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A simple and rapid reversed-phase high-performance liquid chromatographic method for the separation and determination of 4-amino-azobenzene-4′,5-disulfonic acid (AABDS) and its process-related impurities was developed. The separation was achieved on a μ-Bondapak C18 column using 0.15 M ammonium sulfate-acetonitrile (55:45) (v/v) as eluent. A UV-visible spectrophotometric detector fixed at 386 nm was used both for detection and quantitation. The method was used not only for quality assurance but also for process development and wastewater management of AABDS.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 92
    Electronic Resource
    Electronic Resource
    Fiber Conditioners for Solid Phase Microextraction: Design, Testing, and Application (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 343-347 
    Details
    ISSN: 0935-6304
    Keywords: SPME ; desorption ; fiber conditioning ; field sampling ; sample preparation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 93
    Electronic Resource
    Electronic Resource
    Comparison of Different Di-tert-butyldimethyl-Silylated Cyclodextrins as Chiral Stationary Phases in Capillary Gas Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 569-575 
    Details
    ISSN: 0935-6304
    Keywords: Enantioselective gas chromatography ; cyclodextrins ; heptakis(2,6-di-O-tert-butyldimethylsilyl)-β-cyclodextrin ; heptakis(2,6-di-O-tert-butyldimethylsilyl-3-O-methyl)-β-cyclodextrin ; heptakis(3,6-di-O-tert-butyldimethylsilyl-2-O-methyl)-β-cyclodextrin ; octakis(2,6-di-O-tert-butyldimethylsilyl-3-O-methyl)-γ-cyclodextrin ; thermodynamic parameters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Separation factors and thermodynamic data for the separation of various chiral analytes on different di-O-tert-butyldimethyl-silylated cyclodextrin derivatives are collected and described. Modifying the substitution pattern of the tert-butyldimethylsilyl group in position 2 and 3 or changing from β- to γ-cyclodextrin significantly affects the separation properties of the cyclodextrin derivatives.
    Additional Material: 9 Ill.
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  • 94
    Electronic Resource
    Electronic Resource
    Considerations on Static and Dynamic Sorptive and Adsorptive Sampling to Monitor Volatiles Emitted by Living Plants (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 547-553 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; static and dynamic headspace sampling ; sorptive and adsorptive extraction ; plant volatiles ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Static and dynamic headspace sampling have been applied for the enrichment of volatiles emitted by living plants. For solid phase microextraction (SPME) the sorptive fibers polydimethylsiloxane (PDMS) and polyacrylate (PA) have been compared and, in accordance with the like-like principle, polar compounds exhibit more affinity for the PA fiber while apolar solutes favor the PDMS fiber. For dynamic sampling, tubes packed with PDMS particles show greater inertness than Tenax; some Tenax decomposition products, e.g. benzaldehyde and acetophenone, interfere with the analyses. With PDMS particles operated in the breakthrough mode, the obtained profiles are similar to those obtained by SPME on the PA fiber. Recoveries relative to a packed PDMS bed are 85% for Tenax, 2.4% for SPME-PDMS, and 6.2% for SPME-PA.
    Additional Material: 5 Ill.
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  • 95
    Electronic Resource
    Electronic Resource
    Liquid Chromatography of Unstable Zinc Dithiocarbamates. Application to Rubber Gloves Analysis (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 565-566 
    Details
    ISSN: 0935-6304
    Keywords: Liquid chromatography ; zinc dithiocarbamate ; vulcanization accelerator ; rubber gloves ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 96
    Electronic Resource
    Electronic Resource
    Synthesis and Silica-Based Immobilization of Monofunctionalized Heptakis(2,6-di-O-methyl-3-O-pentyl)-β-cyclodextrin for Enantioselective Capillary-HPLC (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 583-589 
    Details
    ISSN: 0935-6304
    Keywords: Monofunctionalized cyclodextrins ; enantioselective capillary-HPLC ; immobilized chiral stationary phases ; separation of chiral drugs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Heptakis(2,6-di-O-methyl-3-O-pentyl)-β-cyclodextrin was monofunctionalized by the regioselective introduction of exactly one ω-epoxyoctyl group at the primary site of the cyclodextrin. The site-specifically substituted cyclodextrin was immobilized to commercially available aminopropyl silica by nucleophilic opening of the epoxy function of the spacer substituent resulting in a lipophilic chiral stationary phase with broad applicability for enantiomer separations in capillary-HPLC under reversed-phase conditions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 97
    Electronic Resource
    Electronic Resource
    Determination of Molecular Weight Distribution of Lignin Derivatives by Aqueous Phase High Performance Size Exclusion Chromatography (HPSEC) (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 693-696 
    Details
    ISSN: 0935-6304
    Keywords: High performance size exclusion chromatography ; molecular weight ; lignin derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 98
    Electronic Resource
    Electronic Resource
    Biodegradation of Pharmaceutical Residues Investigated by SPE-GC/ITD-MS and On-Line Derivatization (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 474-478 
    Details
    ISSN: 0935-6304
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Solid-phase extraction, on-line derivatization, and measurement by ion trap mass spectrometry (ITD-MS) were used to investigate the biological degradation of pharmaceutical residues (clofibric acid, ibuprofen, diclofenac). The results of the single steps of sample pretreatment and analytical determination are reported. MS/MS measurements were performed on an ITD-MS by selecting collision induced dissociation of the molecular ions (M+) as parent ions to defined daughter ions. A pilot sewage plant and biofilm reactors operating under oxic and anoxic conditions were run as model systems with synthetic sewage water containing 10 to 50 mg/L dissolved organic carbon (DOC) and pharmaceuticals in concentrations of 10 μg/L. Clofibric acid displayed its persistent character in all cases. The pilot sewage plant and the oxic biofilm reactor showed comparable results for diclofenac and ibuprofen, which both were partly degraded. These results can explain the occurrence of these substances in sewage effluents and in the aquatic environment. A high degree of degradation was found especially for ibuprofen in the oxic biofilm reactor, which was attributed to adaptation of the biofilm to the residue. Two metabolites of ibuprofen could be identified on the basis of their mass spectra and comparison with literature data, viz. hydroxyibuprofen and carboxyibuprofen.
    Additional Material: 8 Ill.
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  • 99
    Electronic Resource
    Electronic Resource
    Determination of Scoparone in Citrus Roots by Micellar Electrokinetic Capillary Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 519-521 
    Details
    ISSN: 0935-6304
    Keywords: Scoparone ; phytoalexin ; citrus ; MEKC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A new MEKC method has been developed to determine the amount of the phytoalexin, scoparone, in Citrus roots. The separation and analysis was achieved with a running buffer of 100 mM SDS, 25 mM phosphate and 12% (v/v) methanol pH 6.2. Separation was performed at 12 kV with 25°C and UV detection at 200 nm. A near complete recovery of scoparone was obtained with the extraction procedure. The MEKC method was compared with a fluorescence TLC method. The detection limit for scoparone with the MEKC method (2 μg/mL) was better than the TLC method (10 μg/mL).
    Additional Material: 2 Ill.
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  • 100
    Electronic Resource
    Electronic Resource
    A New Monolithic-Type HPLC Column For Fast Separations (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 93-99 
    Details
    ISSN: 0935-6304
    Keywords: HPLC ; monolithic column ; silica rod column ; fast separations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The application of a new silica-based, monolithic-type HPLC-column for fast separations is presented. The column is prepared according to a new sol-gel process, which is based on the hydrolysis and polycondensation of alkoxysilanes in the presence of water soluble polymers. The method leads to “rods” made of a single piece of porous silica with a defined pore structure, i. e. macro- and mesopores. The main feature of silica rod columns is a higher total porosity, about 15% higher than of conventional particulate HPLC columns. The resulting column pressure drop is therefore much lower, allowing operation at higher flow rates including flow gradients. Consequently, HPLC analysis can be performed much faster, as it is demonstrated by various applications.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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