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  • 2000-2004
  • 1990-1994  (1,008)
  • 1920-1924
  • 1993  (1,008)
  • Organic Chemistry  (969)
  • MRI
  • 1
    Electronic Resource
    Electronic Resource
    MRI of soft tissue tumors (1993)
    Springer
    Skeletal radiology 22 (1993), S. 77-84 
    Details
    ISSN: 1432-2161
    Keywords: MRI ; Soft tissue tumors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance imaging (MRI) is the only noninvasive method of defining a soft tissue tumor. The extent of the tumor and the question of involvement or noninvolvement of various adjacent tissues and structures can be determined. This information, determination of lymphatic and distant metastatic spread, is invaluable for staging and management of the disease. Whether or not the tumor type can be reliably determined, or even whether the malignant or benign nature of the tumor can be ascertained on MRI examination, is open to question. Review of the literature indicates proponents on both sides of the issue. This review illustrates the imaging features that are relevant to suggesting a histologic diagnosis, and the pitfalls that are encountered in trying to determine the malignancy or benignity of a lesion. The clinical significance of these determinations is also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197982
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  • 2
    Electronic Resource
    Electronic Resource
    Neurosarcoidosis with unusual MRI findings (1993)
    Springer
    Neuroradiology 35 (1993), S. 146-148 
    Details
    ISSN: 1432-1920
    Keywords: Sarcoidosis ; Intra-cranial ; MRI ; Gadolinium ; CT scan
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract This 53-year-old white male presented with a 4-month-history of weakness and pain. Despite an initial partial response to steroid therapy, his neurologic deterioration progressed culminating in paraparesis, paresthesias, urinary incontinence, altered mentation and a 20 lb weight loss. A gadolinium-enhanced MRI study showed a pattern suggestive of perivascular involvement. A subsequent cerebral biopsy was diagnostic for neurosarcoidosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00593973
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  • 3
    Electronic Resource
    Electronic Resource
    MRI in acute transverse myelopathy (1993)
    Springer
    Neuroradiology 35 (1993), S. 221-226 
    Details
    ISSN: 1432-1920
    Keywords: MRI ; Acute transverse myelopathy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The MRI examinations of seven patients with acute transverse myelopathy (ATM) were analysed. The patients were examined 2–5 times during the course of their disease with short and long TR/TE spin-echo sequences in the sagittal projection. A previous history of autoimmune disorder and/or signs of infection at the onset of ATM were present in all cases. Cerebrospinal fluid analysis showed local synthesis of immunoglobulin in the nervous system in three cases and signs of infectious myelitis in one. During the acute phase four patients had local enlargement of the cord and all had increased signal on long TR/TE sequences. The outcome was grave in the majority of patients and there seemed to be a correlation between the degree of cord enlargement, persistence of increased signal intensity and limited recovery. Atrophy and remaining high signal intensity were noted on late MRI in patients with poor outcome. In one patient with probable anterior spinal artery occlusion, cavitation of the cord was seen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588501
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  • 4
    Electronic Resource
    Electronic Resource
    Pathological findings correlated with MRI in HIV infection (1993)
    Springer
    Neuroradiology 35 (1993), S. 264-268 
    Details
    ISSN: 1432-1920
    Keywords: HIV ; MRI ; Basal ganglia ; postmortem examinations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI forms an important part of the assessment of patients with HIV-related disease presenting with cerebral smyptoms. Eleven formalin-fixed brains were studied at 0.5 T using T2- and T1-weighted sequences. In two cases of progressive multifocal leucoencephalopathy and one case each of toxoplasmosis and lymphoma, the extent of white matter abnormality seen on MRI corresponded broadly with that on pathological examination. In general, however, histological changes were more frequent than lesions on MRI. Cases in which abnormalities were not seen with standard MRI included those with multiple tuberculous granulomata, multinucleate giant cells, microglial nodules, perivascular cuffing and cytomegalovirus inclusions. A common finding on MRI was punctate or patchy high signal in the basal ganglia on T2-weighted scans, seen in six cases. Corresponding histological changes included calcification of vessels with widened perivascular spaces, and mineralised neurones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00602609
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  • 5
    Electronic Resource
    Electronic Resource
    In vivo MRI of the fetal brain (1993)
    Springer
    Neuroradiology 35 (1993), S. 431-436 
    Details
    ISSN: 1432-1920
    Keywords: MRI ; Fetal brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report MRI of the brain in 45 fetuses; the findings were confirmed by pathological examination or postnatal neuroradiological studies. MRI necessitates medication to eliminate fetal motion; curare was injected into the umbilical cord, and MRI is therefore limited to cases in which umbilical cord puncture is indicated. T1-weighted images were obtained in axial, sagittal and coronal planes; the last of these was generally as the most useful as regards morphology. We demonstrated cerebral malformations (n=13), brain haemorrhage (n=1), a facial angioma (n=1), a facial mass (n=1), hydrocephalus (n=5), unilateral ventricular enlargement (n=1), atrophy (n=4), a porencephalic cyst (n=1) and normal appearances of the brain in 18 cases. Twenty-two of the fetuses were born alive, and the clinical and/or neuroradiological examination confirmed the antenatal findings. The diagnosis was also confirmed in 8 cases in which a neuropathological examination was possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00602823
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  • 6
    Electronic Resource
    Electronic Resource
    Epidural spinal abscess containing gas: MRI demonstration (1993)
    Springer
    Neuroradiology 35 (1993), S. 497-498 
    Details
    ISSN: 1432-1920
    Keywords: Spinal epidural abscess ; Spinal air ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of spinal epidural abscess in which MRI demonstrated intraspinal gas is reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588704
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  • 7
    Electronic Resource
    Electronic Resource
    MRI of cranial chordomas: the value of gadolinium (1993)
    Springer
    Neuroradiology 35 (1993), S. 543-545 
    Details
    ISSN: 1432-1920
    Keywords: Chordoma ; Chondroid chordoma ; Gadolinium ; MRI ; Skull base, neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Two intracranial chordomas are presented: a typical chordoma and a chondroid tumour. MRI with gadolinium showed different enhancement patterns, which may be related to pathological findings. The value of differentiating the two types of chordoma lies in their very different prognosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00588719
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  • 8
    Electronic Resource
    Electronic Resource
    Moyamoya disease in childhood: a familial case report (1993)
    Springer
    Child's nervous system 9 (1993), S. 215-219 
    Details
    ISSN: 1433-0350
    Keywords: Moyamoya disease ; Children ; Cerebral angiography ; MRI ; Seizures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Moyamoya is an obstructive cerebrovascular disease characterized by a cerebral angiographic picture of stenosis or occlusion of main cerebral arteries with an abnormal vascular network at the base of the brain. No definitive cause has been found for this disease and opinion is still divided between a congenital and an acquired etiology. Hemiplegia of sudden onset and epileptic seizures are the prevailing presentation in childhood, while subarachnoid bleeding occurs more frequently in adults. We report a new case of childhood moyamoya with clinical onset of the neurological symptoms within the 3rd year of life; during the child's illness the maternal grandmother presented with moyamoya disease too. Antiaggregating and calcium-antagonist drugs seem effective in preventing further vascular accidents, while a surgical approach is not possible. Computed tomography, single positron emission computed tomography, and magnetic resonance imaging are very useful in the diagnosis of this rare disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00303572
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  • 9
    Electronic Resource
    Electronic Resource
    Pyknodysostosis: Imaging and laboratory observations (1993)
    Springer
    Calcified tissue international 53 (1993), S. 170-173 
    Details
    ISSN: 1432-0827
    Keywords: Pyknodysostosis ; MRI ; Monocyte function tests ; Interleukin-1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Pyknodysostosis is a rare form of sclerosing bone dysplasia with autosomal recessive inheritance. Affected members of two families were assessed as follows: three patients underwent densitometry measurements and bone scans; four patients underwent magnetic resonance imaging (MRI) and an immunological investigation, as well as a detailed endocrinological and biochemical laboratory review. Densitometry measurements revealed values of up to 291% of age-matched normal controls; this increased bone density was mainly in the trabecular bone and not in the cortical bone. The MRI showed the cortex to be of normal thickness, whereas the increase in trabecular bone limited the space within the medullary canal. Bone scans and single photon emission computerized tomography in three patients showed an increased uptake of [99mTc]methylene diphosphonate of up to 538% of age-matched controls, which reflected the increased bone density. Monocyte function tests demonstrated a normal phagocytic capacity, but their killing activity was impaired. Interleukin-1 secretion was also impaired, which may point to the pathogenesis of the disease, in view of its function as an osteoclast activator and its role in bone resorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01321833
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  • 10
    Electronic Resource
    Electronic Resource
    A study on peritumoural brain oedema around meningiomas by CT and MRI scanning (1993)
    Springer
    Acta neurochirurgica 125 (1993), S. 41-46 
    Details
    ISSN: 0942-0940
    Keywords: Brain oedema ; meningioma ; CT ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary There is a great variability in the amount of peritumoural brain oedema accompanying meningiomas. In a previous study it was found that the degree of brain oedema in the white matter around meningiomas correlated with disruption of the layers (especially the cerebral cortex), which separate the tumour from the white matter, as well as with the size and histological subtype of the tumour. In the present study comprising 9 meningiomas, the volume of oedema was calculated by integration of the cross-sectional oedematous areas on serial MRI slices. The volume of oedema was zero in 3 cases and ranged from 11 to 176.4 ml in the other 6 cases. The MRI-scans also showed disruption of the cortex in all cases, ranging from slight to severe. T1 and T2 measurements were made at the level of maximum extension, using a mixed sequence at a field strength of 1.5 T. From the T2 values tissue water content in % was calculated using the equations: WC=39.36/(R2 + 37.2) for cortex, and WC=29.63/(R2 + 27.8) for white matter. These had been obtained by correlating water content with relaxation rates, measured in vitro on human brain autopsy specimens which were subjected to hydration with distilled water or dehydration by hyperosmolar solutions. Mean water content amounted to 82.53% for normal cortex, 74.72% for normal white matter, and 84.59% for oedematous white matter around the tumour. On the assumption that the spread of contrast agent marks the advancement of the front of oedema produced by the tumour, CT-studies were made before, and at 1 1/2, 3 and 6h after contrast infusion. The increase in diameter of the contrast-stained area on the CT-scan allows calculation of the excess of oedema production per unit tumour volume. Of 6 tumours with oedema (mean peritumoural water content of 91% and mean volume of oedema of 69.2 ml) the production excess at the steady-state was 0.18–1.08 ml/h/cm3 tumour volume, whereas 3 tumours without associated oedema had a production excess of 0.03–0.12 ml/h/cm3. Moreover, penetration of the cortex seems to constitute a separate factor determinig the spread of oedema.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01401826
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  • 11
    Electronic Resource
    Electronic Resource
    Diagnosis and results of different treatment regimes in patients with spinal abscesses (1993)
    Springer
    Acta neurochirurgica 125 (1993), S. 105-114 
    Details
    ISSN: 0942-0940
    Keywords: Spinal abscess ; epidural ; subdural ; surgical treatment ; antibiotics ; risk factors ; diagnostic procedures ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Bacterial abscesses involving the spinal canal are associated with a high morbidity and mortality. Most frequently, these lesions are found in the epidural, rarely in the subdural space. In this report, our clinical material consists of a series of 16 patients treated during the last seven years. The clinical presentation included local neurological signs (back pain, para-/tetraparesis, bladder dysfunction), disturbances of consciousness (ranging from drowsiness to deep coma) and general inflammatory signs (meningism, fever). All patients presented with risk factors (septic foci, chronic diseases, and iatrogenic causes). Laboratory investigations revealed typically pathological blood sedimentation rate, leucocytosis and CSF-pleocytosis. Radiologically, the diagnosis was confirmed by myelography, CT and preferably MRI. The abscesses were located epidurally in 14 and subdurally in 2 cases. The surgical treatment included laminectomy, or multiple flavectomies in extensive lesions. Drainage systems (either simple silicon outflow drains or suction-/irrigation systems) were installed in all cases, as well as antibiotic treatment. Results of treatment: Following an observation period of 0,5–6 years, we found complete recovery in six (38%) cases, six (38%) others were mildly disabled and four (25%) patients died. Focussing on the results of the two different drainage systems, we found a statistically significant superiority of the inflow-/outflow system. Complications included mandatory re-exploration, post-inflammatory hydrocephalus, syringomyelia, spinal instability, surgical treatment of peripheral septic foci and therapy resistant septicaemia. In conclusion, we propose that spinal epi-or subdural abscesses require surgical evacuation, using a suction-/irrigation drainage system, as well as antibiotic and intensive care treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01401836
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  • 12
    Electronic Resource
    Electronic Resource
    Conjoined lumbosacral nerve roots (1993)
    Springer
    Acta neurochirurgica 120 (1993), S. 155-158 
    Details
    ISSN: 0942-0940
    Keywords: Myelography ; MRI ; conjoined nerve roots ; lumbosacral
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Conjoined lumbosacral nerve roots is a congenital anomaly that may produce lumbosciatic pain. When symptomatic and undiagnosed, it may be one of the causes of failed back syndrome. Diagnosis with water-soluble contrast myelography has a frequency of 4%. Anatomical studies have shown to have an incidence of 14%. High quality Magnetic Resonance Imaging (MRI) with coronal views may reveal this condition without recurring to computed tomography (CT)-myelography. In this paper we describe our recent experience with five consecutive cases observed during a one year period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02112035
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  • 13
    Electronic Resource
    Electronic Resource
    Repeat angiography and magnetic resonance imaging (MRI) of dissecting aneurysms of the intracranial vertebral artery (1993)
    Springer
    Acta neurochirurgica 121 (1993), S. 123-129 
    Details
    ISSN: 0942-0940
    Keywords: Dissecting aneurysm ; repeat angiography ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We here present 4 cases with dissecting aneurysm (DA) of the intracranial vertebral artery, who were followed up by repeat cerebral angiography and MRI. The patients consisted of 2 males and 2 females, and the mean age was 43 years. Two cases were associated with polyarteritis nodosa (PN) and hypertension, respectively. Three of the cases developed subarachnoid haemorrhage (SAH), while the other one suffered from lateral medullary syndrome. In cerebral angiography, “pearl and string” signs were revealed in all cases, while a “double lumen” indicating a true diagnostic sign of DA was demonstrated in only one case. Repeat angiography showed that a bleb formation with a bulging of the aneurysmal sac was seen in 2 cases, and an irregularity of the wall in one case. On the other hand in one case, the ectatic part shrank, while the stenotic part was restored. In magnetic resonance imaging (MRI), a hyperintensity mass on T 1-weighted image (T 1-WI) adjacent to flow void suggesting either an intramural haematoma or a linear shape hyperintensity on T1-WI were demonstrated in 3 cases. In the follow up MRI done in 2 cases, a serial change in the intensity from iso-intensity to hyperintensity on T 1-WI was observed in one case suggesting intramural haemorrhage, while an enlargement of the ectatic flow void was seen in the other case. Three of 4 cases were operated on by trapping of the aneurysms. One, who had systemic vascular diseases due to PN, and repeat angiography showed a regression of the aneurysm, was conservatively treated. The outcome was excellent in the 3 surgical cases, whilst the one medically treated case was also excellent without any rebleeding. In conclusion, repeat neuro-imaging procedures are strongly recommended to clarify the possibility of a spontaneous repair of the dissection, and to consider the surgical strategy for the lesion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01809262
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  • 14
    Electronic Resource
    Electronic Resource
    Diffuse leptomeningeal melanomatosis of the spinal cord: a case report (1993)
    Springer
    Acta neurochirurgica 121 (1993), S. 206-211 
    Details
    ISSN: 0942-0940
    Keywords: Leptomeningeal melanosis ; MRI ; peritoneal shunt ; arachnoid cyst
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A rare case of diffuse leptomeningeal melanosis presenting with symptoms of spinal cord compression due to the presence of anterolateral arachnoid cyst and treated with Spetzler's drainage system is reported. The diagnosis of diffuse melanosis of the leptomeninges is rarely possible during life. In the present case MRI was of great help in the definition of the limits of the pathological process and the presence of the anterior compressing cyst. After laminectomy and a biopsy of the pathological tissue which achieved the histological diagnosis, an external drainage was inserted to reduce the cyst extension and to exclude the presence of melanocytes in the cystic fluid before a peritoneal shunt was placed. At 8 th month of follow-up the patient is doing well with a dramatic reduction of symptoms and a significant reduction of spinal cord compression. The diagnostic role of MRI and the relationship between leptomeningeal melanosis and arachnoid cyst are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01809277
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  • 15
    Electronic Resource
    Electronic Resource
    Evaluation of MRI score in the differentiation between glioblastoma multiforme and metastatic adenocarcinoma of the brain (1993)
    Springer
    Acta neurochirurgica 122 (1993), S. 54-59 
    Details
    ISSN: 0942-0940
    Keywords: Glioblastoma multiforme ; metastatic adenocarcinoma ; MRI ; MRI score
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors statistically analyzed the MR configurations of 14 glioblastoma multiformes (GBMs) and 15 metastatic adenocarcinomas (MACs) of the brain in order to distinguish these two histological types on MR images. MR configurations were classified and scored upon the 9 criteria of heterogeneity, cyst or necrosis, haemorrhage, crossing of the midline by the tumour, oedema or mass effect, border definition, flow void sign, degree and heterogeneity after contrast enhancement. The mean value of GBMs was 1.47±0.22, and that of MACs was 0.91±0.37 (P〈0.001). GBMs had significantly higher values in five out of the nine criteria: border definition, heterogeneity, crossing of the midline of the tumour, flow void sign, and degree of the contrast enhancement (P〈0.001–0.05). Border definition was the best criterion for distinguishing two histological types. Six cases of MACs displayed hypo-intense lesions on T2 weighted images in contrast to GBMs which showed hyperintense lesions in all cases. In 4 out of the 6 MACs which were shown as hyperintensities on T2 weighted images, a hypo-intense peritumoural rim was noticed between the tumour parenchyma and the surrounding oedema. These data strongly suggest that GBMs and MACs can be distinguished on MR image by using MRI score.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01446987
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  • 16
    Electronic Resource
    Electronic Resource
    Therapy evaluation of neuroendocrine liver metastases with contrast-enhanced MRI (1993)
    Springer
    European radiology 3 (1993), S. 19-25 
    Details
    ISSN: 1432-1084
    Keywords: Liver ; MRI ; Neuroendocrine tumours ; Therapy monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Seventeen patients with neuroendocrine liver metastases, 14 of whom were treated with interferon, were examined with MRI before and after contrast administration to evaluate whether there were signal characteristics, differences in homogeneity and/or contrast enhancement patterns that indicated response to or failure of treatment. Of the treated patients 6 objectively responded to treatment (OR), 3 had progressive disease (PD) and 5 had stable disease (SD). A significant difference was found between the SD, untreated (UT) and OR groups of patients in terms of T1 (P = 0.01) and contrast enhancement (P = 0.02). The signal intensity ratio (SIR) in T2-weighted images between tumour and liver was significantly different (P = 0.05) between the OR and PD groups. This indicates that MRI may be used in therapy monitoring of patients with neuroendocrine metastases. Neuroendocrine metastases in the OR group had the same T1 and SIR values as those reported for haemangiomas, while patients in the PD, SD and UT groups had SIR values similar to those for colorectal metastases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173517
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  • 17
    Electronic Resource
    Electronic Resource
    Gd-DTPA enhanced MRI of breast: the most sensitive method for detecting multicentric carcinomas in female breast? (1993)
    Springer
    European radiology 3 (1993), S. 223-226 
    Details
    ISSN: 1432-1084
    Keywords: MRI ; Female breast imaging ; Mammography ; Breast cancer ; Multicentricity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The first publications on the use of magnetic resonance for breast imaging (MRBI) appeared more than 10 years ago. According to the literature between 14% and 47% of all breast carcinomas are multicentric carcinoma (MCC), a substantial number of which are not detected by conventional mammography. In a prospective study our purpose was to establish a clinically relevant procedure with MRBI for women with a single suspect lesion on mammography. Eight (32%) of 25 patients with histologically confirmed carcinoma had an MCC. Seven MCC were detected with MRBI and only one was diagnosed by mammography; one was discovered with neither MRBI nor mammography. MRBI proved to be the superior technique, with a sensitivity of 0.88 compared with 0.13 for mammography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425898
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  • 18
    Electronic Resource
    Electronic Resource
    The value of gadoterate meglumine as a gastrointestinal contrast agent in MRI (1993)
    Springer
    European radiology 3 (1993), S. 248-252 
    Details
    ISSN: 1432-1084
    Keywords: Gadolinium ; Gastrointestinal tract ; MRI ; MRI contrast enhancement ; Paramagnetic contrast agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To evaluate the safety and efficacy of a gadoterate meglumine formulation as an oral contrast agent, MRI (0.5 T) was performed on 29 patients with abdominal disease before and after administration of contrast material. The patients ingested 16 ml/kg of a gadoterate meglumine solution (10 g/l glucose, 2 mmol/l gadoterate meglumine) over 1 h. Fourteen per cent of patients had mild side effects related to the contrast agent. Significant hyperintense contrast enhancement was achieved for the stomach and duodenum allowing better delineation of gastric and duodenal walls, entire pancreas and spleen on T1- and T2-weighted spin echo sequences. In 5 patients more diagnostic information was available from post-contrast images compared with precontrast images. This study shows that gadoterate meglumine is a safe and well-tolerated contrast agent that improves MRI of the proximal gastrointestinal tract and upper abdomen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425903
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  • 19
    Electronic Resource
    Electronic Resource
    Accuracy of diagnostic imaging in nephroblastoma before preoperative chemotherapy (1993)
    Springer
    European radiology 3 (1993), S. 115-122 
    Details
    ISSN: 1432-1084
    Keywords: Computed tomography ; Diagnosis ; MRI ; Radiography ; Ultrasonography ; Wilms' tumour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The main strategy in the treatment of nephroblastoma, as described in protocol SIOP 9/GPO, is preoperative chemotherapy for patients between 6 months and 16 years of age. Before treatment the diagnosis is made only by diagnostic imaging without biopsy. From July 1988 to February 1991, 130 children with the tentative diagnosis of nephroblastoma were treated preoperatively. The initial diagnostic images (excretory urography, ultrasound, CT, MRI) have been analysed both prospectively and retrosperatively and the findings correlated with the intraoperative and histological results. Of the preoperatively treated patients 93.8% had a Wilms' tumour or one of its variants. Five patients had a different malignant tumour and 3 patients, i.e. 2.3% of those preoperatively treated or 1.6% of all registered patients, had benign tumours of the kidney. Wilms' tumour generally presented as a well-defined mass with an inhomogeneous morphology on CT. On ultrasound only 24% of the tumours were homogeneous. Intratumoral haemorrhage and cystic areas occurred frequently; calcifications were rare (8%). With regard to caval involvement only ultrasound and MRI enabled the correct diagnosis, while CT could not differentiate compressions from invasion. The pretherapeutic diagnostic imaging was of sufficient accuracy to start preoperative chemotherapy without diagnostic biopsy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169783
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  • 20
    Electronic Resource
    Electronic Resource
    Pseudotumoral hepatic actinomycosis: contribution of diagnostic and interventional radiology (1993)
    Springer
    European radiology 3 (1993), S. 180-182 
    Details
    ISSN: 1432-1084
    Keywords: Liver ; actinomycosis ; CT ; MRI ; Percutaneous biopsy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of pseudo-tumoral actinomycosis of the liver was examined by ultrasonography (US), computed tomography (CT), and magnetic resonance imaging (MRI). MRI with injection of Gadolinium-DOTA (Gd-DOTA) revealed irregular structures in the center with peripheral enhancement. Diagnosis was obtained on percutaneous biopsy in view of characteristic sulfur on the samples. Percutaneous drainage was not necessary and medical treatment with antibiotheraphy alone was successful.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00169795
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  • 21
    Electronic Resource
    Electronic Resource
    T1, T2 and proton density measurements in the grading of cerebral gliomas (1993)
    Springer
    European radiology 3 (1993), S. 49-52 
    Details
    ISSN: 1432-1084
    Keywords: Brain tumor ; MRI ; T1 ; T2
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The possibility that cerebral tumours may be graded by measuring T1 or T2 with magnetic resonance (MR) imaging was studied. A consecutive series of patients with subsequently verified gliomas was enrolled, and studied with MR. Patients who had prior surgical, chemotherapeutic or steroid treatment were excluded. Single slice multiple saturation recovery and multiple spin echo techniques were used to measure T1, T2 and proton density in the tumour. In 33 patients with cerebral gliomas there were 5 grade I, 12 grade II, 7 grade III and 9 grade IV. T1 and T2 values tended to be smaller in grade I gliomas than in grades II, III and IV gliomas. Relaxation parameters overlapped considerably in tumours with different grades. Proton density values did not show much change between different grades of gliomas. Relaxation parameters cannot be used to determine tumour grade reliably.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173524
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  • 22
    Electronic Resource
    Electronic Resource
    Radiographic, CT and MRI spectrum of hydatid disease of the chest: a pictorial essay (1993)
    Springer
    European radiology 3 (1993), S. 62-70 
    Details
    ISSN: 1432-1084
    Keywords: Chest ; CT ; Echinococcosis ; Hydatid disease ; MRI ; Radiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Thirty patients with thoracic hydatidosis (Echinococcus granulosus) were studied. The hydatid cysts were located in the lung parenchyma (70%), mediastinum (6.7%), inside the heart (10%), the pleurae (10%) and the chest wall (3.3%). complications of thoracic hydatid cysts, such as rupture, infection, pleural involvement, spread and calcifications are presented. Computed tomography (CT) without and/or with contrast enhancement was performed in all patients (30). Findings from conventional chest radiographs were compared with CT and confirmed by pathology (30). In 10 cases (33.3%), magnetic resonance imaging was also performed. The diagnostic spectrum of hydatid cysts, including variations and developmental stages, is presented in this pictorial essay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173526
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  • 23
    Electronic Resource
    Electronic Resource
    MRI, CT, sonography and thallium-technetium subtraction scintigraphy for the detection of parathyroid disease: a four-year experience (1993)
    Springer
    European radiology 3 (1993), S. 71-76 
    Details
    ISSN: 1432-1084
    Keywords: Hyperparathyroidism ; MRI ; CT ; Sonography ; Scintigraphy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Sonography, subtraction scintigraphy, computed tomography and MRI were compared in 100 patients who had surgery 105 times for hyperparathyroidism (HPT). Surgical and pathological data were available for all operations. A total of 105 MR, 77 CT, 84 sonograms and 70 subtraction scintigrams were performed. The ability of the imaging modalities, individually and in combination, to detect HPT, histology, size, concomitant thyroid disease and location of the diseased glands has been evaluated. For primary HPT, sensitivity ranged from 68% for MRI to 40% for scintigraphy but was much lower for tertiary HPT with all modalities. The ability to identify diseased glands was strongly size dependent for all methods. If patients had had previous neck surgery, the most sensitive methods were MRI and scintigraphy and this also held true for patients with concomitant thyroid disease and ectopically located glands. The findings presented suggest that while sonography may be the only imaging examiantion warranted in newly diagnosed parathyroid disease, recurrent disease should be examined pre-operatively with MRI and possibly subtraction scintigraphy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00173527
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  • 24
    Electronic Resource
    Electronic Resource
    Magnetic resonance imaging in patients with claustrophobia: results of treatment with intramuscular clorazepate (1993)
    Springer
    European radiology 3 (1993), S. 355-356 
    Details
    ISSN: 1432-1084
    Keywords: Claustrophobia ; Clorazepate ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Between July 1991 and April 1992 1125 patients were examined with MRI, 34 (3%) of whom were treated with 50 mg clorazepate intramuscularly because of severe claustrophobia. The examination was successfully completed in 31 patients (91%). Only minor side effects were observed. Clorazepate suppresses the symptoms of claustrophobia, allowing the MRI examination to proceed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167468
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  • 25
    Electronic Resource
    Electronic Resource
    MRI of spinal hematoma as a result of lumbar puncture (1993)
    Springer
    European radiology 3 (1993), S. 386-388 
    Details
    ISSN: 1432-1084
    Keywords: Subarachanoid haemorrhage ; Intradural haematoma ; Spinal ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A 59-year-old woman was suspected of having meningitis. A lumbar puncture was performed for CSF analysis; however, a traumatic tap induced hemorrhage in the subarachnoid space and formed a hematoma from the L3 to the S1 level. This resulted in a paraparesis. Myelography showed a band-like filling defect and a subsequent computed tomography (CT) myelogram showed a soft tissue mass in the intradural space. T1 weighted magnetic resonance imaging revealed a lesion with moderate hyperintensity within the dural sac, hinting that the lesion was a hematoma. Laminectomy was performed, and the hematoma was entirely removed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167477
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  • 26
    Electronic Resource
    Electronic Resource
    Contrast enhancement of the gastrointestinal tract on MR images using intravenous gadolinium-DTPA (1993)
    Springer
    Abdominal imaging 18 (1993), S. 215-219 
    Details
    ISSN: 1432-0509
    Keywords: Abdomen ; MRI ; Intestine contrast enhancement ; Gastrointestinal tract, MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Gadopentetate dimeglumine was administered intravenously to 16 patients undergoing abdominal magnetic resonance (MR) imaging. T1-weighted and fat-suppressed T1-weighted images were acquired before and after intravenous administration of 0.1 mmol/kg gadopentetate dimeglumine. The stomach, small bowel, and colon were analyzed regarding the presence and relative intensity of contrast enhancement. Diffuse enhancement of the gastrointestinal tract wall was observed in all patients following contrast material administration. Such enhancement was most conspicuous on fat-suppressed T1-weighted images. Quantitative measurements indicated that the wall of the gastrointestinal tract enhanced approximately 100% with gadopentetate dimeglumine. This study demonstrates that enhancement of the normal gastrointestinal tract occurs routinely when intravenous gadopentetate dimeglumine is administered, and such enhancement should not be considered indicative of gastrointestinal pathology. Furthermore, it suggests the potential utility for using intravenous rather than orally administered contrast agents to provide enhancement of the gastrointestinal tract on MR images.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198104
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  • 27
    Electronic Resource
    Electronic Resource
    Carcinoid of the intrahepatic ducts (1993)
    Springer
    Abdominal imaging 18 (1993), S. 242-244 
    Details
    ISSN: 1432-0509
    Keywords: Carcinoid tumor ; Bile ducts ; Bile duct tumor ; Carcinoid ; MRI ; Carcinoid angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Carcinoid tumors of the biliary tree are rare. To the best of our knowledge, this is the first reported case of an intrahepatic ductal carcinoid and the thirteenth reported case of biliary carcinoid. The radiographic appearance is variable. A brief review of the previously described cases is presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00198113
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  • 28
    Electronic Resource
    Electronic Resource
    Anatomy of the acromial arch: correlation of anatomy and magnetic resonance imaging (1993)
    Springer
    Surgical and radiologic anatomy 15 (1993), S. 63-70 
    Details
    ISSN: 1279-8517
    Keywords: Shoulder ; Acromion ; Coracoacromial ligament ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé A partir de la lecture rétrospective de 179 dossiers d'IRM représentant quatre populations (patients présentant un conflit sans traumatisme reconnu (n=90), une douleur d'épaule post-traumatique (n=28), une instabilité ou une luxation (n=36) et sujets témoins (n=25)), les auteurs proposent des critères morphologiques pour définir des voûtes présumées normales et des voûtes susceptibles de rendre compte d'un conflit sous acromial. La voûte sous acromiale est présumée “normale” ou non conflictuelle si, sur les vues sagittales et frontales, elle apparait parallèle à la tête humérale et/ou il existe un liseré graisseux qui s'interpose entre la voûte et le m. supra-épineux. La voûte sous acromiale est présumée agressive ou susceptible de rendre compte d'un conflit si, sur l'une des vues sagittale ou frontale, il est observé une zone de rétrécissement du défilé sous acromial avec une empreinte de la voûte sur le tendon du m. supra-épineux ou un amincissement tendineux au niveau ou juste en dehors de cette zone de rétrécissement. A partir de ces critères, la lecture des 179 dossiers d'IRM permet de mettre en évidence une différence significative de répartition des voûtes dans les quatre populations. Les voûtes agressives s'observent chez 45.5 % des patients présentant un conflit, 25 % des patients pr%esentant une douleur au décours d'un traumatisme, 8.9 % des sujets examinés au décours d'une luxation aigue ou récidivante et 12 % des sujets témoins. A l'inverse, la voûte présumée normale est retrouvée chez 56 % des sujets témoins, 55 % des patients examinés pour une luxation, 25 % des douleurs d'épaule post traumatique et seulement 5.5 % des patients présentant un conflit clinique. Le conflit sous acromial peut être le fait d'une dysplasie acromiale de type 3 décrit par Bigliani ou d'un épaississement du ligament au niveau de son insertion acromiale. Ce travail est complété par 15 dissections anatomiques qui confirment la constance de l'insertion du ligament coraco-acromial sur la face inférieure de l'acromion le long de son bord latéral.
    Notes: Summary Based on a retrospective study of 179 MRI records covering four populations (patients presenting with impingement without known injury (n=90), post-traumatic shoulder pain (n=28), instability or dislocation (n=36) and controls (n=25)), morphologic criteria are suggested to define presumedly normal arches and arches compatible with subacromial impingement. The subacromial arch is presumed normal or without impingement if the sagittal and frontal views show it to be parallel to the humeral head, and/or if there is a fatty layer interposed between the arch and the supraspinatus m. The arch is presumed “aggressive” or actually capable of giving rise to impingement if, in either the sagittal or frontal view, there is a zone of narrowing of the subacromial passage with an impression of the arch on the supraspinatus tendon or tendinous thinning at this level or just lateral to this narrowed zone. Based on these criteria, study of the 179 MRI records demonstrated a significant difference of distribution of the arches in the four populations. “Aggressive” arches were found in 45.5% of patients with impingement, 25% of patients with posttraumatic pain, 8.9% of patients with an acute or recurrent dislocation and 12% of controls. Conversely, a presumedly normal arch was found in 56% of the controls, 55% of patients with dislocation, 25% of posttraumatic painful shoulders and only 5.5% of patients with clinical impingement. Subacromial impingement may be due to the type 3 acromial dysplasia described by Bigliani or to a thickening of the coracoacromial ligament at its acromial attachment. This study was supplemented by 15 anatomic dissections which confirmed the regularity of attachment of the coracoacromial ligament at the inferior aspect of the acromion along its lateral border.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01629865
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  • 29
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    Electronic Resource
    Iatrogenic epidural spinal abscess (1993)
    Springer
    Journal of molecular medicine 71 (1993), S. 780-786 
    Details
    ISSN: 1432-1440
    Keywords: Epidural spinal abscess ; MRI ; Cerobrospinal fluid ; Antibiotic treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We present four cases of iatrogenic epidural spinal abscess directly caused by externally introduced catheters or probes. In two patients the infection spread per continuum, in the other two patients due to haematogenous dissemination. Clinical presentation in each case included generalized malaise with fever, signs of meningeal inflammation and focal neurological signs at the spinal level. The diagnosis was made on the basis of inflammatory changes in the cerebral spinal fluid and localization of the abscess by means of computer and magnetic resonance tomography. A broad-spectrum antibiotic regimen included a penicillinase-resistant preparation because of the frequent involvement of Staphylococcus aureus. It is our experience that a good outcome is dependent on early and specific treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190318
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  • 30
    Electronic Resource
    Electronic Resource
    Chronological changes of MRI findings on striatal damage after acute cyanide intoxication: Pathogenesis of the damage and its selectivity, and prevention for neurological sequelae: A case report (1993)
    Springer
    European archives of psychiatry and clinical neuroscience 243 (1993), S. 71-74 
    Details
    ISSN: 1433-8491
    Keywords: Cyanide ; basal ganglia ; anti-epileptic drugs ; calcium antagonist ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 31-year-old male technician in an electroplating factory, who had been suffering from the temporal lobe epilepsy for 24 years and from hypertension for 3 years, took an unknown amount of potassium cyanide apparently over the lethal dose, in an attempt to commit suicide. He was treated successfully and survived without any neurological sequelae. The electroencephalograms and the nature of the seizures were not different before and after the poisoning. The T2-weighted magnetic resonance images at 9 and 51 days after the poisoning showed bilateral elevation of signals in the caudate nuclei and the putamina. At the 143th and 286th days, T2-weighted high-resonance areas were restricted to the lateral portion of the putamina. The T1-weighted images at the 51st day showed abnormal signal elevations in both putamina, while those of 9th, 143th and 286th days were mainly normal. Selective vulnerability of the putamen and the caudate nucleus may be due to their specific structural properties of high oxygen and glucose utilization, and enzyme distribution. Both chronological changes of striatal damage and the absence of neurological sequelae in this patient suggest the possibility that anti-epileptics and a calcium antagonist played a neuroprotective role in the acute cyanide intoxication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02191567
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  • 31
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    Electronic Resource
    Crossed aphasia. Report of a rare case in a glioblastoma patient (1993)
    Springer
    Neurological sciences 14 (1993), S. 329-332 
    Details
    ISSN: 1590-3478
    Keywords: Crossed aphasia ; hemispheric specialization ; MRI ; GBM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Sommario Viene descritto il caso di una donna destrimane che manifestò disturbi afasici all'esordio clinico di un glioblastoma emisferico destro. La paziente presentava afasia di Wernicke ed eminattenzione spaziale sinistra. L'integrità dell'emisfero sinistro fu documentata con la Risonanza Magnetica. Alcuni aspetti della specializzazione emisferica per le funzioni linguistiche, prassiche e spaziali vengono brevemente discussi.
    Notes: Abstract A rare case of a right-handed (on the Edinburgh Inventory) woman who developed aphasia at the clinical onset of a right hemisphere glioblastoma (GBM) is reported. She showed Wernicke aphasia and left spatial neglect. The integrity of the left hemisphere was assessed by Magnetic Resonance Imaging (MRI). A few aspects of hemispheric specialization for language, praxias and spatial abilities are briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02339301
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  • 32
    Electronic Resource
    Electronic Resource
    Processing MRI data for electromagnetic source imaging (1993)
    Springer
    Medical & biological engineering & computing 31 (1993), S. 600-606 
    Details
    ISSN: 1741-0444
    Keywords: EEG ; Image processing ; MEG ; MRI ; Segmentation ; Three-dimensional rendering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Estimation of the source of activity in the brain from electro- and magneto-encephalographic measurements is becoming increasingly common. Structural information could assist in improving the calculation of the sources as well as providing the context of the source location. Magnetic resonance images are very useful for this purpose, but they still need to undergo various processing steps. The paper describes in details a practical method for full automatic processing of MRI images of a head, including segmentation of the images and triangulation of the surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441808
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  • 33
    Electronic Resource
    Electronic Resource
    Gliomatosis cerebri in a young patient showing various cranial nerve manifestations: a case report (1993)
    Springer
    Brain tumor pathology 20 (1993), S. 93-96 
    Details
    ISSN: 1861-387X
    Keywords: Gliomatosis cerebri ; MRI ; Low-grade astrocytoma ; IFN-β ; PET
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A case of gliomatosis cerebri in a 27-year-old man showing various cranial nerve manifestations is described. He was diagnosed as having cranial mononeuritis multiplex (bilateral oculomotor nerve paralysis, left facial nerve paralysis, bulbar palsy manifestations, and hypoglossal nerve paralysis) and was hospitalized in the neurology department on August 1, 2000. Although he continued to visit the neurology department after discharge, his manifestations showed no improvement. He was sent to our department for brain biopsy in August 2001. A biopsy performed at the Sylvian fissure from the frontal lobe/temporal lobe cortex showed high intensity on T2-weighted and Flair magnetic resonance imaging (MRI). The pathological findings were diffuse low-grade astrocytoma infiltrating between the pia mater and the cerebral cortex. We believed that the astrocytoma spreading on the subpia mater was responsible for the various cranial nerve manifestations, and we started whole-brain irradiation (46 Gy)+interferon (IFN)-β D.I.V. from September 2001. The pathological findings of the brain biopsy showed diffuse astrocytoma. The clinical presentation was dramatically improved after radiotherapy. It seemed that this tumor had spread along the subpia mater and subependyma. When he was discharged in early December, he walked by himself. The characteristic features of this case are that no lesion in the cerebellum or brain stem was found on MRI, even though the main manifestations were cerebello-brain stem manifestations, and biopsy of the cerebral cortex revealed astrocytoma. It should be noted that the clinical manifestations of astrocytoma in some cases are dissociated from the imaging observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02483454
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  • 34
    Electronic Resource
    Electronic Resource
    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050101
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  • 35
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    Electronic Resource
    Rats with portacaval shunt as a potential experimental pharmacokinetic model for liver cirrhosis: Application to carvedilol stereopharmacokinetics (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 1-7 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; conjugates ; protein binding ; tissue binding ; stereoselective pharmacokinetics ; first-pass effect ; drug metabolism ; liver disease ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As an experimental model for reduced liver function rats with surgical portacaval shunts (pcs) may be used. Carvedilol, a nonselective β-adrenoceptor antagonist with vasodilating activity, is extensively metabolised by phase I as well as phase II pathways. In order to study the stereoselective pharmacokinetics of carvedilol in liver disease, pcs and control rats were given rac-carvedilol intravenously and p.o. The carvedilol enantiomers and their conjugates were assayed in plasma, urine, and bile. Carvedilol was highly bound to plasma proteins; binding was reduced by pcs. In all groups, the plasma concentrations of (R)-carvedilol exceeded those of (S)-carvedilol significantly. In comparison to the control group the plasma concentrations of both enantiomers increased after pcs, while the difference between the stereoisomers decreased. The total clearance decreased proportionally to the decrease in liver weight (30%). Both the apparent oral clearance, as well as its stereoselectivity were reduced, by up to 90 and 43%, respectively. The biliary clearance of the parent drug after i.v. dosage increased in rats with pcs due to the reduced hepatic metabolism. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050102
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  • 36
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    Electronic Resource
    Enantioselective determination of hydroxychloroquine and its major metabolites in urine and the observation of a reversal in the (+)/(-)-hydroxychloroquine ratio (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 65-70 
    Details
    ISSN: 0899-0042
    Keywords: stereoselective excretion ; enantioselective ; chromatography ; assay validation ; hydroxychloroquine metabolism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sequential achiral-chiral high-performance liquid chromatographic system has been developed for the quantitation in urine of the enantiomers of hydroxychloroquine (HCQ), and of its 3 major metabolites, desethylhydroxychloroquine (DHCQ), desethylchloroquine (DCQ), and bisdesethylchloroquine (BDCQ). HCQ and its metabolites were separated and quantified on a cyano-bonded phase, and the enantiomeric ratios were determined using a Chiral-AGP chiral stationary phase. The assay validation and application of this method to a preliminary study in a human volunteer are presented. In this subject, the initial 0-4 h urine contained the 2 HCQ enantiomers in a ratio of (+)-HCQ:(-)-HCQ of 3:2; by the 2,064 h of the study, this ratio had reversed to (+)-HCQ:(-)-HCQ of 3:7. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050205
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  • 37
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    Electronic Resource
    The effects of (±)-, (+)-, and (-)-atenolol, sotalol, and amosulalol on the rat left atria and portal vein (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 8-14 
    Details
    ISSN: 0899-0042
    Keywords: (±)- ; (±)- ; (-)-atenolol ; sotalol ; amosulalol ; enantiomers ; β1 - and β2-adrenoceptors ; rat left atria and portal vein ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of (±)-, (+)-, and (-)-atenolol, sotalol, and amosulalol alone on the rat left atria and portal vein and on the respective β1- and β2-adrenoceptor-mediated responses to isoprenaline have been determined. (±)-Atenolol at 10-6 M had no effect whereas high concentrations of (+)- and (-)-sotalol, 10-5-10-4 M, and (±)-, (+)-, and (-)-amosulalol depressed the response of the rat left atria to cardiac stimulation which indicates membrane stabilizing activity. None of the drugs tested had any effect alone on the rat portal vein. The order of potency as antagonists was (±)-amosulalol 〉 (±)-atenolol 〉 (±)-sotalol at β1-adrenoceptors and (±)-amosulalol 〉 (±)-sotalol 〉 (±)-atenolol at β2-adrenoceptors. (±)-Atenolol and (±)-amosulalol are β1-selective whereas (±)-sotalol is β2-selective. For each of the racemic β-blockers, the β1- and β2-adrenoceptor blocking activity was predominantly due to the (-)-enantiomer. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050103
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  • 38
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    Electronic Resource
    Absolute configuration of (+)-cis-2,3-dihydro-2-[(methylamino)methyl]-1- [4-(trifluoromethyl)phenoxy]-1H-indene hydrochloride, a chiral serotonin uptake inhibitor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 20-23 
    Details
    ISSN: 0899-0042
    Keywords: (+)-(2S,3S)-cis-2,3-dihydro-2-[(methylamino)methyl]-1-[4-(trifluoromethyl)phenoxy]-1H-indene hydrochloride ; serotonin uptake inhibitor ; circular dichroism ; benzene sector and chirality rules ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The absolute configuration of (+)-cis-2,3-dihydro-2[(methylamino)methyl]-1-[4-(trifluoromethyl)pheno〈y]-1H-indene hydrochloride, the more active enantiomer of a new serotonin inhibitor, was established as 1S,2S. This assignment was based on the application of the benzene sector and chirality rules to the interpretation of the inhibitor's circular dichroism spectrum and the spectra of other related chiral 1-substituted 2,3-dihydro-1H-indenes. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050105
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  • 39
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    Electronic Resource
    Influence of uncharged mobile phase additives, pH, and structure differences on retention and enantioselectivity of chiral hexa- and octa-hydrobenzo(g) quinolines on an ovomucoid glycoprotein column (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 36-40 
    Details
    ISSN: 0899-0042
    Keywords: enantiomeric separation ; chiral phase ; ovomucoid ; octahydrobenzo(g) quinoline ; chiral recognition mechanism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomeric resolution of six closely related hexa- and octa-hydrobenzo(g) quinoline racemates by HPLC on an ovomucoid column (Ultron ES-OVM) is described. First, the influence of uncharged mobile phase additives (with different hydrogen bonding properties) and pH on retention and enantioselectivity is investigated. It is shown that an optimum pH of around 6 for the given separations is much more important than the choice of modifier. Second, the influence on enantioselectivity of small differences in molecular structure is examined. In one case a large difference is obtained for diastereomeric racemates depending on the cis- or trans-configuration of the quinoline skeleton. Higher flexibility of the solute seen in the cis enantiomers seems to improve enantioselectivity. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050108
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  • 40
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    Electronic Resource
    Resolution of rac-ketoprofen esters by enzymatic reactions in organic media (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 320-328 
    Details
    ISSN: 0899-0042
    Keywords: lipases ; amano M-AP-10 ; transesterification ; hydrolysis ; aminolysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enzyme-catalyzed reactions in organic media of rac-ketoprofen esters with different nucleophiles such as alcohols, amines, and water have been studied. Among the parameters optimized are the enzyme, the activated substrate, and the solvent. With the enzymes used in this study the preferred substrate was the trifluoroethyl ester of rac-ketoprofen (rac-2), whose (R)-enantiomer reacted preferentially. The enzyme of choice was the lipase M-AP-10 from Mucor miehei and best results were obtained with diisopropyl ether as solvent. Three different methods have been scaled-up for the resolution of 75-150 g of substrate: transesterification with 1-butanol (90% yield of (S)-ketoprofen, 88% ee), transesterification with 2-(2-pyridyl)ethanol (94% yield, 92% ee), and hydrolysis in wet organic solvent (93% yield, 97% ee). Despite the comparable chemical and optical yields obtained with these three methods, the use of 2-(2-pyridyl)ethanol and the hydrolysis allowed a much easier work-up and isolation of the desired (+)-(S)-ketoprofen. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Tab.
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    URL: http://dx.doi.org/10.1002/chir.530050508
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    Development of the enzyme-catalysed Baeyer-Villiger reaction as a useful technique in organic synthesis (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 334-337 
    Details
    ISSN: 0899-0042
    Keywords: lactone synthesis ; stereoselective oxidation ; monooxygenases ; Pseudomonas putida NCIMB 10007 ; Acinetobacter calcoaceticus NCIMB 9871 ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The current practices of using monooxygenase enzymes to perform regio- and stereoselective oxidation reactions in organic syntheses are reviewed. The isolation of a monooxygenase from Pseudomonas putida NCIMB 10007 and its use in the conversion of bicyclo[3.2.0]hept-2-en-6-one into two isomeric optically active lactones is described. The monooxygenase utilises NADH as cofactor and NADH-recycling is accomplished using formate and formate dehydrogenase. As alternative methodology, it is shown that a secondary alcohol can be converted into a chiral lactone using a dehydrogenase and a monooxygenase working in tandem with in situ cofactor recycling. © 1993 Wiley-Liss, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050510
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    Biological significance of the enantiomeric purity of drugs (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 350-355 
    Details
    ISSN: 0899-0042
    Keywords: adrenoceptors ; formoterol ; eudismic ratios ; diastereomers ; stereoselectivity ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The knowledge that enantiomers of chiral compounds may differ widely in biological activity, qualitatively as well as quantitatively, is not new. Nevertheless most of the pharmacological data available to date on chiral drugs are obtained from experiments with racemates which assume that the biological activity generally resides in one of the enantiomers. With the advancements made in stereospecific synthesis and stereoselective analysis of drugs pharmacologists are now offered new possibilities to explore the steric aspects of drug action. This survey will discuss pharmacological data obtained with enantiomer pairs of phenylethylamine derivatives which interact with adrenergic mechanisms. The degree of resolution is seldom specified in published work on stereoselectivity of drugs. In a recent study from our laboratory the enantiomers of the β2-adrenoceptor agonist formoterol and their diastereomers have been evaluated. We found that the (R;R)-enantiomer was by far the most potent. However, the relative potencies obtained for the (R;S)-, (S;R), and (S;S)- isomers were critically dependent on the degree of enantiomeric purity. It is concluded that the certainty of potency ratios observed for chiral drugs is limited by the enantiomeric purity and by unspecific effects of the least active enantiomer at very high concentrations. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050514
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    Chiral symmetry breaking: Experimental results and computer analysis of a liquid-phase autoxidation (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 341-345 
    Details
    ISSN: 0899-0042
    Keywords: amplification of enantiomeric excess ; autocatalysis ; origin of optical activity ; models ; nonlinear kinetics ; simulations ; stereoselectivity ; tetralin hydroperoxide ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The autoxidation of tetralin is treated as a model reaction system to define the applicability of stereospecific autocatalysis. This concept, predicting a spontaneous amplification of enantiomeric excess generated by an autocatalytic chemical reaction, is used in several theoretical models as an explanation for the origin of natural optical activity. The reaction system investigated obeys the basic criteria of these models: a chiral intermediate (tetralin hydroperoxide) is produced from an achiral substrate (tetralin) via an autocatalytic pathway where the feedback mechanism is expected to generate a state of broken chiral symmetry. In order to test the amplification capacity of this reaction a computer analysis of the kinetic scheme is performed. This simulation is derived from the known kinetic scheme of autoxidation and is validated by fitting the experimentally observed data of hydroperoxide evolution. Calculations show that this model allows powerful amplification of enantiomeric excess and a transient amplification of the optical rotation. It is also demonstrated that the model system exhibits pronounced sensitivity toward any loss of absolute configuration of the involved chiral species. Since an amplification effect results exclusively at a high degree of stereoselectivity, it is concluded that stereospecific autocatalysis is possible in systems which show template reactions, crystallization, or colloidal effects. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050512
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    Racemization of chlorthalidone in the presence of liposomes (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 370-374 
    Details
    ISSN: 0899-0042
    Keywords: (+)-chlorthalidone ; racemization ; pH profile ; influence of liposomes ; reaction kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The extent of racemization of (+)-chlorthalidone as a function of pH is examined. The minimum of the log K/pH curve is pH 3. The reaction mechanism of inversion is postulated to involve a carbenium cation over the entire pH range and a ring opening reaction in the alkaline range. The influence of liposomes on the inversion rate is also studied, retardation of the racemization rate being observed with increasing liposome concentration. A model of drug distribution between liposome phase and aqueous phase based on the Nernst distribution principle is presented and reaction kinetic aspects are considered. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050518
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    Abstracts of selected posters (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 400-402 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050523
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    Announcement (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 403-403 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050524
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  • 47
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    Stereoselectivity of the aliphatic hydroxylation of 6-n-propylchromone-2-carboxylic acid in rat and guinea pig (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 191-198 
    Details
    ISSN: 0899-0042
    Keywords: stereoselectivity ; regioselectivity ; aliphatic hydroxylation ; rat ; guinea pig ; 6-n-propylchromone-2-carboxylic acid ; Mosher's esters ; 1H-NMR configurational assignment ; 19F-NMR configurational assignment ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Following administration of 6-n-propylchromone-2-carboxylic acid (6-n-PCCA) (500 μmol/kg) to male rats, three metabolic products were detected and isolated from the 0-24 h urine. All were identified as resulting from oxidation exclusively along the 6-n-propyl moiety. Some 66% of the dose was excreted in the 0-24 h urine, 55% of which was 6-PCCA, with 15% as (6-1′-hydroxypropyl)chromone-2-carboxylic acid (6-1′-HPCCA), 22% as 6-(2′-hydroxypropyl)chromone-2-carboxylic acid (6-2′-HPCCA), and 4% as (6-3′-carboxypropyl)chromone-2-carboxylic acid (6-3′-CPCCA). Derivatization of the methyl esters of the hydroxylated metabolities with S-α-methoxy-α-(trifuloromethyl)-phenylacetyl chloride (Mosher's reagent) allowed the evaluation of urinary enantiomeric composition by HPLC and assignment of their absolute configurations by NMR. This was found to be 90:10 (R/S) for 6-2′-HPCCA, and 7:93 (R/S) for 6-1′-HPCCA. When rats were dosed with the racemic 1′- and 2-hydroxy metabolites; no stereoselective metabolism or excretion was observed. Administration of 6-n-PCCA to male guinea pigs revealed that this species was unable to metabolise this compound. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050316
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  • 48
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    Separation of N-arylthiazoline-2-(thi)-one atropisomers on p-methylbenzoyl cellulose beads: A factorial design approach (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 207-212 
    Details
    ISSN: 0899-0042
    Keywords: chiral HPLC ; solvent effect ; quantitative substituent effects ; molecular recognition mechanism ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A two level full factorial design has been applied to quantify the effect of three selected structural parameters on the capacity factors and chiral separation of atropisomers in N-arylthiazoline-2-(thi)-ones derivatives on tris(p-methylbenzoyl) cellulose beads. The behavior of the two enantiomers is influenced by different factors which might result from different retention sites within the same stationary phase. It appears that the two enantiomers behave independently on the CSP, the order of elution and separation being controlled by a minor steric modification in a very precise location in the molecule for one enantiomer. The methodology of the experimental design allows the comparison of equations generated from data issued from designed compounds. These equations afford much more information than the step by step comparison of individual molecules. In our case, the tris(p-methylbenzoyl)cellulose beads and microcrystalline cellulose triacetate appear as complementary CSPs for the resolution of atropisomers of the series studied. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050403
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  • 49
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    Direct resolution of enantiomers of basic imidazol-2-yl-substituted alcohols by gas chromatography on chirasil-val (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 229-231 
    Details
    ISSN: 0899-0042
    Keywords: enantiomer resolution ; gas chromatography ; Chirasil-Val ; alcohol ; basic compounds ; imidazole ; chiral discrimination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct resolution of enantiomers of a series of imidazol-2-yl-substituted alcohols has been achieved by gas chromatography on a well-deactivated fused-silica capillary column, coated with L-Chirasil-Val as the chiral stationary phase. The separation of these basic compounds is accomplished without exaggerated peak tailing. Compared to simpler alcohols the resolution factors (α) observed are extraordinarily large. While the imidazolyl substituent may contribute to the mechanism of the chiral discrimination, the crucial interaction is assumed to be through the hydroxy group, based on the observation that the resolution factors for the corresponding O-acetyl derivatives are markedly reduced. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050407
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  • 50
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    Chiral separation of amines using reversed-phased ion-pair chromatography (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 241-245 
    Details
    ISSN: 0899-0042
    Keywords: chiral counterion ; reversed-phase chiral ion-pair chromatography ; diastereomeric ion-pairs ; chiral mobile phase additive ; (-)-2,3:4,6,-di-O-isopropylidene-2-keto-L-gulonic acid ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The direct separation of enantiomeric amines has been carried out using a chiral counter ion, (-)-2,3:4,6,-di-O-isopropylidene-2-keto-L-gulonic acid [(-)-DIKGA] dissolved in polar mobile phases, water:methanol or isopropanol:acetonitrile. High separation factors, α = 1.2-1.7, were obtained for several compounds of pharmacological interest such as metoprolol, oxprenolol, remoxipride, mefloquine and p-OH-ephedrine. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050410
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    Enzymatic and chromatographic chiral discrimination of racemic (thio)glycidyl esters: Part II. Optical resolution of racemic (thio)glycidyl esters on modified cellulose chiral stationary phases (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 255-257 
    Details
    ISSN: 0899-0042
    Keywords: cellulose tris(3,5-dimethylphenyl carbamate) ; cellulose tribenzoate ; chiral HPLC ; enantiomers ; temperature dependence ; chiral recognition ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral chromatography on cellulose tris(3,5-dimethylphenyl carbamate) (Chiralcel OD) and cellulose tribenzoate (Chiralcel OB) coated stationary phases has been successfully used for the optical resolution of rac-(thio)glycidyl esters (acetate, propionate, butyrate). Glycidyl esters could sufficiently be resolved on the OD column whereas for the thio analogues baseline resolution is obtained on CSP OB using hexane/2-propanol mobile phases. The separation factor (α) and resolution (RS) depend on column temperature, eluent composition, and flow rate, respectively. Best results were obtained for the butyrates and at low temperatures in general. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050413
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    Preparative scale enantioseparation of a chiral epoxide: Comparison of liquid chromatography and simulated moving bed adsorption technology (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 267-271 
    Details
    ISSN: 0899-0042
    Keywords: simulated moving bed technology ; chiral separation ; cellulose triacetate ; preparative scale liquid chromatography ; racemic epoxide ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The feasibility of using simulated moving bed technology (SMB) for chiral separation on cellulose triacetate is demonstrated on the preparative scale: 1 kg of a chiral epoxide has been separated. On comparing SMB technology with conventional liquid chromatography it turns out that the main advantage of SMB lies in the significant reduction of mobile phase consumption. The process design for SMB is made theoretically and the predictions are confirmed by our pilot study. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050415
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  • 53
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    Chiral recognition by 1H-NMR, EPR, and ENDOR spectroscopy (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 282-287 
    Details
    ISSN: 0899-0042
    Keywords: phenoxyl radicals ; hydrogen bond ; host guest interactions ; diastereomers ; absolute configuration ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral recognition with magnetic methods requires the formation of diastereomers. Due to the variety of appropriate reactions, hydrogen bond formation, esterification, and acetalization as well as host-guest interactions were chosen for basic investigations. The results obtained indicate that in the case of diamagnetic compounds the chemical shifts and for paramagnetic compounds the β-proton coupling constants are the most useful parameters. By combination of both pieces of information, assignment of the absolute configuration was achieved. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050418
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    Editorial: Note from the European editor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. iv 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050502
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    Dissymmetric calix[4]arenes: Optical resolution of some conformationally fixed derivatives (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 310-314 
    Details
    ISSN: 0899-0042
    Keywords: chromatography ; chiral stationary phases ; separation of enantiomers ; CD spectra ; C4 and C2 symmetry ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various possibilities to obtain intrinsically chiral calix[4]arenes are discussed. The enantiomers of three 1,3-dietheresters and one monoether compound derived from dissymmetric calix[4]arenes with C4 symmetry were separated by HPLC using chiral stationary phases and characterized by their CD spectra. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050506
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  • 56
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    Optical resolution by crystalline inclusion formation using new lactic acid derived hosts (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 315-319 
    Details
    ISSN: 0899-0042
    Keywords: chiral selectors ; natural product derived hosts ; optically active hosts ; clathrate hosts ; bulky 1,2-diols ; inclusion compounds ; host-guest complexes ; chiroselective cocrystallization ; chiroselective vapor sorption ; preparative scale enantioseparation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New optically active host compounds for chiroselective crystalline inclusion formation derived from natural lactic acid are synthesized. They enable useful enantiomer separations of different chiral compounds via cocrystallization and sorption on preparative scale including various ketones, lactones, alcohols, sulfoxides, and methyloxiranes. In the cases of 3-methylcyclohexanone, 4-methyl-δ-valerolactone, and 2-phenylpropanol, ees 〉 99% were obtained from one cocrystallization step using these hosts. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050507
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  • 57
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    Stereoselective distribution of acenocoumarol enantiomers in human plasma: Chiral chromatographic analysis of the ultrafiltrates (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 346-349 
    Details
    ISSN: 0899-0042
    Keywords: stereoselective protein binding ; chiral liquid chromatography ; human serum albumin ; α1-acid glycoprotein ; anticoagulant ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Stereoselectivities for the binding of rac-acenocoumarol to human serum albumin (HSA), α1-acid glycoprotein (AGP), and human plasma were determined by chiral HPLC analysis of the ultrafiltrates on a Chiral-AGP column. The results confirmed the previously detected inverse stereoselectivities; for HSA the ratio of the enantiomeric constants was KR/KS ∼ 2, while for AGP it was KR/KS ∼ 0.3. In plasma the contribution of HSA dominates, although in pathological states, elevated AGP levels may compensate for stereoselective distribution. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050513
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  • 58
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    High-Performance liquid chromatography (HPLC) chiral separations of guaifenesin, methocarbamol, and racemorphan (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 238-240 
    Details
    ISSN: 0899-0042
    Keywords: chiral HPLC ; Chiralcel OD ; Chiralcel OD-R ; guaifenesin ; methocarbamol ; dextromethorphan ; levomethorphan ; racemorphan ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: HPLC chiral separations on silica gel coated with derivatized cellulose stationary phases are described. Most examples make use of the Chiralcel OD column from Daicel, Inc. With a judiciously chosen mobile phase, baseline separations of the enantiomers can be achieved. If those separations are used as a base for enantiomeric purity determination, detectable limits of 0.1% of the minor enantiomer are routinely accessible. Examples are given concerning separations of guaifenesin, methocarbamol, and racemorphan. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050409
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  • 59
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    Enzymatic and chromatographic chiral discrimination of racemic (thio)glycidyl esters: Part I. A chemoenzymatic approach to both enantiomers of thioglycidyl esters (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 250-254 
    Details
    ISSN: 0899-0042
    Keywords: enzymic kinetic resolution ; porcine pancreatic lipase (PPL) ; hydrolysis ; transesterification ; acylation ; enol esters ; chiral HPLC ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Both hitherto unknown (+)-(R)- and (-)-(S)-thioglycidyl esters, (R)-(2) and (S)-(2), have been synthesized with different high enantiomeric excesses (ee) by two routes from the corresponding rac-glycidyl esters rac-(1). The first includes a porcine pancreatic lipase (PPL)-mediated kinetic resolution of these esters followed by sulfuration with practically complete inversion to the (+)-(R)-enantiomer (+)-(R)-(2) (36-86% ee). (-)-(S)-Thioglycidyl esters (-)-(S)-(2) are obtained by the reverse reaction sequence (43-80% ee). In the latter case the hydrolysis rate is lower than that of analogous glycidyl esters. Moreover, the dependence of enantiomeric excess on the size of the acyl-group is of the opposite tendency. Therefore, in both cases suitable selection of the acid residue gives rise to maximum enantioselectivity. The irreversible lipase-catalyzed acylation of rac-glycidol and rac-thioglycidol, however, was found to be a less suitable alternative. The enantiomeric excess of recovered homochiral esters was determined by chiral chromatography using modified cellulose stationary phases (OB, OD). © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050412
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    Feasibility of chiral discrimination using X-ray anomalous scattering (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 277-281 
    Details
    ISSN: 0899-0042
    Keywords: anomalous dispersion ; absolute structure ; enantiomer determination ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The paper discusses several feasibility prediction criteria with particular emphasis on light atom molecules. For several examples of refined absolute structures, feasibility predictions are calculated and compared with a posteriori calculated values of the Bijvoet ratio. An extension of the Pathasarathy table of the expected value of the Bijvoet ratio is given for parameter ranges corresponding to light anomalous scatters. Practical conclusions are drawn for absolute structure determination of compounds containing oxygen or nitrogen as anomalous scatterers. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Tab.
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    URL: http://dx.doi.org/10.1002/chir.530050417
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    Announcement (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 293-293 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050420
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    Stereoselectivity in β-cyclodextrin complexation of 1,4-dihydropyridine derivatives (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 288-292 
    Details
    ISSN: 0899-0042
    Keywords: calcium channel blockers ; enantiomers ; stereoselectivity ; solubilization ; enantiomeric resolution ; stereodifferential complexation ; 1H-NMR chiral recognition ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Structure-interaction relationships, stereoselectivity, and solubility enhancement in inclusion compexation of β-cyclodextrins (CDs) with some racemic and enantiomerically pure 1,4-dihydropyridine derivatives (DHPs) were investigated. 1:1 and 1:2 (mole ratio) complexes were prepared and characterized by X-ray powder diffraction, differential scanning calorimetry (DSC), MS-FAB spectrometry, 1H-NMR spectroscopy, water and phase solubility. The solubility studies have revealed different complexation equilibria for optically pure DHP enantiomers, and corresponding racemic mixtures in water solutions. By means of 1H-NMR chemical shift measurements, the inclusion of aromatic fragments of racemic and enantiomerically pure DHP molecules within the cavities of different CDs was elucidated. Considerable stereoselectivity in complexation interactions was observed. The results indicate the potential use of cyclodextrins as chiral selectors for enantiomeric resolution of 1,4-DHP calcium antagonists. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050419
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    Chiral discrimination by albumin: A mechanistic study of liquid chromatographic optical resolution of nonaromatic carboxylic acids (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 295-299 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; BSA ; N-alkanoyl-leucines ; chiral recognition ; radiolabeling ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to get further insight into the mechanism by which bovine serum albumin (BSA) discriminates between enantiomers of organic acids, some radioisotopically labeled, nonaromatic carboxylic acids were studied under varying mobile phase conditions. It was found for a series of N-alkanoyl-DL-[3H]leucines that the D-enantiomers were much more strongly retained and that the composition of the mobile phase could be adjusted to give very large (α 〉 20) enantiomeric separation factors. The elution order was consistent with what has been found earlier for other N-acyl derivatives as well as for N-arylcarbamoyl derivatives of simple aliphatic amino acids. A marked increase in the hydrophobic interaction of the D-enantiomers with the chiral phase was found upon a lowering of the mobile phase strength, conditions under which the L-form was only slightly influenced. These and other results are consistent with a chiral recognition model by which inclusion of the compound in a hydrophobic chiral cavity of BSA with simultaneous charge interaction is assumed to take place and whereby discrimination is determined by the steric bulk and orientation of the α-substituent. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050503
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    Enantioselective sequential transformations by use of metal complexes: Tandem-Knoevenagel-hetero-Diels-Alder reactions with new chiral Lewis acids (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 329-333 
    Details
    ISSN: 0899-0042
    Keywords: chiral Lewis acid ; sequential transformations ; domino reaction ; intramolecular hetero-Diels-Alder reaction ; enantioselective cycloadditions ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enantioselective reaction of the aldehydes 1a-g and the 1,3-dicarbonyl compound 2 in the presence of the chiral Lewis acid 5, derived from diacetone glucose, leads in a sequential transformation consisting of a Knoevenagel condensation and an intramolecular Diels Alder reaction to the cycloadducts 4a-g with an ee value up to 88%. The selectivity is strongly dependent upon the temperature and solvent giving best results at room temperature in isodurene; in agreement with the principle of isoinversion, the ee values decrease at lower and higher temperatures. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050509
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    Direct enantiospecific HPLC bioanalysis of (R,S)-atenolol on a chiral stationary phase (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 479-482 
    Details
    ISSN: 0899-0042
    Keywords: chiral resolution ; high-performance liquid chromatography (HPLC) ; β-blocker ; cellulose ; Tris-3,5-dimethylphenylcarbamate ; chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The simultaneous determination of the enantiomers of the β1-selective adrenergic antagonist atenolol in human plasma and urine is described. After an alkaline preextraction atenolol is extracted from biological material at pH 12.3 using dichloromethane/propan-2-ol. The separation of the underivatized enantiomers is achieved by high-performance liquid chromatography on a chiral stationary phase (Chiralcel OD, cellulose tris-3, 5-dimethylphenylcarbamate, coated on silica gel) with fluorimetric detection. (-)-(S)-Pindolol is used as an internal standard. The detection limits of 5 ng/ml enantiomer in plasma and 50 ng/ml enantiomer in urine are sufficient for pharmacokinetic studies after therapeutic doses. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050614
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    Chiral-recognition chromatography of β-blockers on continuous polymer beds with immobilized cellulase as enantioselective protein (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 464-470 
    Details
    ISSN: 0899-0042
    Keywords: continuous bed ; chiral phase ; cellulase ; enantiomers ; HPLC ; β-blockers ; propranolol ; alprenolol ; metoprolol ; labitolol ; practolol ; pindolol ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Columns prepared by coupling cellulase as a chiral selector to silica beads are very efficient for the separation of enantiomers. In this paper we show that continuous polymer beds compete favorably with silica beads as chromatographic supports for such separations. The chiral stationary phase is prepared either by entrapment in and simultaneous covalent linkage of ally1 cellulase to the continuous beds during their preparation or by covalent immobilization of cellulase on an epoxy-activated continuous bed. Enantiomers of β-blockers were separated rapidly and with high resolution. The enantiomers of practolol were thus baseline resolved within 45 sec. The recognition center-or at least part of it - coincides with the active center of the enzyme, since the enantiomers could not be separated in the presence of the competitive enzyme inhibitors cellobiose and D-glucose and the separation was also impaired upon addition of the substrate carboxymethyl cellulose to the eluent. Similar observations have been reported for silica columns derivatized with cellulase. The capacity factor and the separation selectivity could be tuned by the pH and the concentration of the mobile phase, a phosphate buffer. No modifier was required, as is sometimes the case with silica-based supports. The continuous beds give faster enantiomer separations than do columns of silica and are more pH-stable and cost effective to prepare. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050612
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    Synthesis and evaluation of the antidepressant activity of the enantiomers of bupropion (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 495-500 
    Details
    ISSN: 0899-0042
    Keywords: diborane and sodium borohydride reduction ; diastereomeric amino alcohols ; Swern oxidation ; antitetrabenazine activity ; biogenic amine uptake inhibition ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of the enantiomers of bupropion, (rac)-2-tert-butylamino-3′-chloropropiophenone 1 (Wellbutrin®) is described. The enantiomers were compared with the racemate in both the tetrabenazine-induced sedation model and the inhibition of uptake of biogenic amine assay. No significant differences were found in their potencies to reverse tetrabenazine-induced sedation in mice or in their IC50 values as inhibitors of biogenic amine uptake into nerve endings obtained from mouse brain. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Tab.
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    URL: http://dx.doi.org/10.1002/chir.530050704
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    Separation of the enantiomers of some racemic nonsteroidal aromatase inhibitors and barbiturates by capillary electrophoresis (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 516-526 
    Details
    ISSN: 0899-0042
    Keywords: chiral ; cyclodextrin ; drug ; electrophoresis ; micellar electrokinetic ; resolution ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-performance capillary electrophoresis (HPCE) and micellar electrokinetic capillary chromatography (MECC) were applied to the resolution of racemic nonsteroidal antiaromatase drugs and intermediates. Successful results were obtained in both modes using α-cyclodextrin (α-CD), β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), or 2,6-di-O-methyl-β-cyclodextrin (DM-β-CD) as chiral selectors. Depending on the structure of the solute, one of the cyclodextrins was generally better suited for resolution of the racemate. The basic solutes were analyzed under HPCE conditions, whereas the nonionizable compounds such as glutethimide (Doriden®) were analyzed in MECC mode. For the azole-type antiaromatase Fadrozole, both HPCE and MECC modes could be used to achieve the separation of the enantiomers. The influence of experimental factors such as pH, the presence of organic modifier, temperature, the micelle concentration, and the concentration of the chiral selector is also discussed on the basis of the results obtained with some chiral barbiturates. The possibility of analyzing the enantiomers directly in plasma samples was also demonstrated. © 1993 Wiley-Liss, Inc.
    Additional Material: 13 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050708
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    Microbial metabolism of 2-arylpropionic acids: Chiral inversion of ibuprofen and 2-phenylpropionic acid (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 596-601 
    Details
    ISSN: 0899-0042
    Keywords: microbial metabolism ; chiral inversion ; chiral inversion of 2-phenylpropionic acid ; oxidation of ibuprofen ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metabolism of (R,S)-ibuprofen has been investigated in 24 microbial cultures. Of these Cunninghamella elegans, Mucor hiemalis, and Verticillium lecanii catalyzed the oxidation of the drug to 2-[4-(2-hydroxy-2-methylpropyl)phenyl]propionic acid, a known mammalian metabolite. The extent of metabolism was greatest with V. lecanii, with some 47% of the substrate being consumed over a 7-day incubation period. Enantiomeric analysis indicated stereoselective metabolism of (R)-ibuprofen, the enantiomeric composition of the residual substrate being R/S = 0.25. Following a preparative scale incubation of (R,S)-ibuprofen with V. lecanii, in which the reaction was allowed to go to completion, the metabolite was found to be predominantly of the S-configuration (S/R = 2.1), suggesting that chiral inversion of either the drug and/or the metabolite had taken place. Analysis of extracts following incubation of (R,S)-, (R)-, and (S)-2-phenylpropionic acid with V. lecanii, for 21 days, indicated that chiral inversion of the (R)-enantiomer to its optical antipode had taken place. The results of these investigations indicate that microorganisms, in addition to mammals, are able to mediate the chiral inversion of 2-arylpropionic acids. This observation may have implications for the preparation of optically pure 2-arylpropionic acids. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Tab.
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    URL: http://dx.doi.org/10.1002/chir.530050806
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    Stereoselective cyclooxygenase inhibition in cellular models by the enantiomers of ketoprofen (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 589-595 
    Details
    ISSN: 0899-0042
    Keywords: NSAIDs ; enantioselectivity ; prostaglandin E2 ; thromboxane B2 ; HUVEC ; PMN ; keratinocytes ; P388D1 ; platelets ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pharmacological activity of rac-ketoprofen and its enantiomers was investigated in vitro using different cellular models. The effect of these compounds on arachidonic acid metabolism was assessed by measuring the inhibition of prostanoid generation under the action of several agonists. Thus, we have evaluated the inhibition of (1) thromboxane B2 synthesis in rabbit platelets and human polymorphonuclear leukocytes (PMNs), (2) prostaglandin E2 synthesis in three cultured cells, namely human umbilical vein endothelial cells (HUVEC), human keratinocytes, and mouse macrophage-like P388D1 cells. The IC50 values found for (+)-(S)-ketoprofen were in the range between 0.1 nM and 0.8 μM, being slightly lower in all models than those found for rac-ketoprofen (0.4 nM-3 μM). On the other hand, (-)-(R)-ketoprofen showed inhibition of cyclooxygenase only at concentrations two or three orders of magnitude higher than those required for the (+)-(S) enantiomer. These results, obtained with cell types of relevance for inflammatory processes and with compounds of high optical purity, demonstrate that the prostanoid biosynthesis inhibition caused by the drug rac-ketoprofen is exclusively due to its dextrorotatory enantiomer. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050805
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    Resolution of enantiomers by HPLC on tris(4-alkoxyphenylcarbamate)s of cellulose and amylose (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 616-621 
    Details
    ISSN: 0899-0042
    Keywords: cellulose tris(4-isopropoxyphenylcarbamate) ; cellulose tris(3,5-dimethyl-4-methoxyphenylcarbamate) ; amylose tris(3,5-dimethyl-4-methoxyphenylcarbamate) ; optical resolution ; HPLC ; chiral stationary phase ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ten phenylcarbamate derivatives of cellulose and amylose having alkoxy groups such as ethoxy, isopropoxy, and isobutoxy at 4-position, and methyl groups at 3- and 5-positions and methoxy group at 4-position were synthesized and their chiral recognition abilities as stationary phases for high-performance liquid chromatography were investigated and compared to those with tris(4-methoxyphenylcarbamate)s of cellulose and amylose. In 4-alkoxy derivatives of cellulose, chiral recognition ability increased as the bulkiness of 4-alkoxy groups increased. 4-Isopropoxy and 4-isobutoxy derivatives showed high chiral recognition. On the other hand, chiral discrimination of amylose 4-alkoxy derivatives scarcely depended on the bulkiness of the alkoxy group, and 4-methoxy and 4-isopropoxy derivatives showed high chiral recognition. 3,5-Dimethyl-4-methoxyphenylcarbamates of cellulose and amylose possessed higher chiral recognition ability than the corresponding 4-methoxy derivatives. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050809
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    Book review. “Chirality in Industry: The Commercial Manufacture and Applications of Optically Active Compounds,” Edited by: A. N. Collins, G. N. Sheldrake and J. Crosby, New York: John Wiley & Sons, 1992, xii, 409 pages, ISBN: 0-471-93595-6, $135.00 (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 627-627 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050811
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    Ciliotoxicity of intranasal formulations: Menthol enantiomers (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 58-60 
    Details
    ISSN: 0899-0042
    Keywords: menthol ; nasal delivery ; adverse effects ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown, using in vitro measurements of beat frequency of rat tracheal cilia, that (+)-(1S, 2R, 5S)-menthol and (-)-(1R, 2S, 5R)-menthol have equipotent ciliotoxicities despite the fact that inhalation of menthol vapours from the crystals of the pure enantiomers show clearly that the (-)-(1R, 2S, 5R)-menthol produces a more potent cooling sensation. Differential scanning calorimetry demonstrates the formation of a racemic compound when equimolar amounts of the two enantiomers are admixed. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050203
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    An in vitro study of the stereoselective dissolution of (rac)-verapamil from two sustained release formulations (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 84-90 
    Details
    ISSN: 0899-0042
    Keywords: in vitro dissolution ; enantioselective ; enantiomers ; bioequivalency ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereoselectivity of the in vitro dissolution of two commercially available sustained release formulations of rac-verapamil (rac-VER) has been investigated. The studies were carried out using a single-tablet continuous-flow apparatus and the concentrations of R- and S-VER released from the formulations were measured using enantioselective chromatography on a high performance liquid chromatography (HPLC) chiral stationary phase containing immobilized α1-acid glycoprotein (Chiral AGP-column). The data from this study demonstrates that the two formulations have different dissolution profiles and that the amount of drug dissolved was highly dependent on pH. In addition, between pH 3 and 8, the total cumulative amount of R-VER released was greater than the amount of S-VER and a statistically significant difference (P 〈 0.01) was detected at pH 6. The results of this study indicate that bioavailability and bioequivalency studies should consider the possibility of enantioselective dissolution when racemic compounds are present in the formulations. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050208
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    Acid-Catalyzed nucleophilic substitution and racemization of 3-methoxy-N-desmethyldiazepam enantiomers in methanol (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 91-96 
    Details
    ISSN: 0899-0042
    Keywords: 1,4-benzodiazepines ; oxazepam ; 3-O-methyloxazepam ; stereoselective nucleophilic substitution ; kinetics ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: pKa1 values of 3-methoxy-N-desmethyldiazepam in acetonitrile and methanol containing various acid concentrations were determined by spectrophotometry to be 3.5 and 1.3, respectively. Temperature-dependent racemization of enantiomeric 3-methoxy-N-desmethyldiazepam in methanol containing 0.5 M H2SO4 was studied by circular dichroism spectropolorimetry and the racemization reactions were found to follow apparent first-order kinetics. Thermodynamic parameters of the racemization reaction were found to be: Eact = 18.8 kcal/mol, and at 25°C: ΔH
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050209
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    New optically active 1,3-oxathiolanes (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 97-101 
    Details
    ISSN: 0899-0042
    Keywords: 1,3-oxathiolane ; chiral α-methylbenzylamine ; optical resolution ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: cis- and trans-5-Ethoxy-1,3-oxathiolane-2-carboxylic acids were obtained in pure form. The cis isomer was resolved into its enantiomers through diastereoisomeric salt formation with enantiomerically pure α-methylbenzylamine. Reduction of the salt followed by benzoylation led to 2-benzoyloxymethyl-5-ethoxy-2(R)-5(S)-1,3-oxathiolane and 2-benzoyloxymethyl-5-ethoxy-2(S)-5(R)-1,3-oxathiolane, useful intermediates in nucleoside chemistry. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050210
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    The so-called “interconversion” of stereoisomeric drugs: An attempt at clarification (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 105-111 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; racemization ; epimers ; epimerization ; configurational stability ; nonenzymatic reactions ; oxazepam ; amfepramone ; thalidomide ; atropine ; chlorthalidone ; pilocarpine ; 16α-substituted 3-methoxyestrones ; chlorpromazine ; telenzepine ; tofisopam ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A variety of reactions can be categorized under the global concept of the “interconversion of stereoisomers.” Thus, racemization or epimerization can result from inversion of labile chiral centers. From the examples available, some predictive rules are suggested for a chiral center of the type R″R′RC—H undergoing base-catalyzed inversion and a provisional table of affecting groups is presented. Unimolecular inversion of nonsymmetrical, nonplanar ring systems can also result in racemization or epimerization, but no generalization can yet be offered. Beside these cases of nonenzymatic reactions, a limited variety of enzymatic reactions can operate to interconvert stereoisomers, the outcome rarely being a racemic mixture. An important aspect of stereoisomer interconversion is the time scale in which the phenomenon is observed. Thus, several reactions to nonezymatic racemization or epimerization are fast compared to the duration of action of the drug and therefore have pharmacological significance, while other are slower and are of pharmaceutical relevance only. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/chir.530050302
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    In vitro and in vivo irreversible plasma protein binding of beclobric acid enantiomers (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 120-125 
    Details
    ISSN: 0899-0042
    Keywords: beclobrate ; beclobric acid ; acyl glucuronides ; hydrolysis ; isomerization ; irreversible binding ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Acyl glucuronides are known to be labile conjugates, which undergo hydrolysis and bind irreversibly to proteins. The lipid-regulating agent (±)-beclobrate is immediately converted to the free acid after oral administration. Further metabolism leads to formation of the corresponding diastereomeric acyl glucuronides. Beclobric acid glucuronides were quantified by indirect measurement with an HPLC method based on chiral fluorescent derivatization of the carboxylic acid and subsequent normal-phase chromatography. The renal clearance of unchanged drug is low, with almost all drug excreted into urine as glucuronic acid conjugates. Beclobric acid glucuronide is also detectable in plasma. In vitro degradation studies with beclobric acid glucuronide (at a concentration of 5 μM in 150 mM phosphate buffer pH 7.4) exhibited a minor tendency for acyl migration and hydrolysis, i.e., a higher stability than has been observed for the acyl glucuronides of most other drugs. The in vitro degradation half-lives of the two beclobric acid β-1-O-acyl glucuronides were 22.7 and 25.7 h. After incubation with pooled plasma and human serum albumin in buffer pH 7.4 irreversible binding was measured in vitro. No significant difference between the two enantiomers was detected with respect to the magnitude of in vitro irreversible binding. In 3 healthy male volunteers the extent of irreversible binding of both beclobric acid enantiomers to plasma proteins was investigated after single and multiple oral doses of racemic beclobrate (100 mg once daily). Irreversible binding of both enantiomers was observed in all volunteers. The adduct densities for (-)- and (+)-beclobric acid after single 100 mg beclobrate doses were 0.147 × 10-4 and 0.177 × 10-4 mol/mol protein. Multipie dosing increased irreversible binding 3- to 4-fold. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050304
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    Diastereomeric phosphonate ester adducts of chymotrypsin: 31P-NMR measurements (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 143-149 
    Details
    ISSN: 0899-0042
    Keywords: 31P NMR of chymotrypsin adducts ; serine protease adducts ; phosphonate ester-chymotrypsin adducts ; organophosphorus adducts of serine proteases ; diastereomeric serine protease adducts ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Generation of diastereomeric phosphonate ester adducts of chymotrypsin was evidenced for the first time by 31P NMR and spectrophotometric kinetic measurements. 31P NMR signals were recorded for 4-nitrophenyl 2-propyl methylphosphonate (IMN) at 32.2 ppm and for its hydrolysis product at 26.3 ppm downfield from phosphoric acid. The inhibition of α-chymotrypsin at pH 〉 8.0 by the faster reacting enantiomer of IMN or 2-propyl methylphosphonochloridate (IMCl), or other phosphonate ester analogs of these compounds, all caused a ∼6.0 ppm downfield shift of the 31P signal to the 39-40 ppm region. IMN, when applied below the stoichiometric amount of chymotrypsin, under the same conditions, generated two signals, at 39.0 and at 37.4 ppm. Scans accumulated in hourly intervals showed the decomposition of both diastereomers, with approximate half-lives of 12 h at pH 8.0 and 22°C, into a species with a resonance at 35.5 ppm. The most likely reaction to account for the appearance of this new peak is the enzymic dealkylation of the isopropyl group from the covalently bound phosphonate ester. We base this conclusion mostly on the similarity of the upfield shift to the hydrolysis of phosphonate esters. Contrary to experience with phosphate ester adducts of serine proteases, no signal was detected higher than 25.0 ppm downfield from phosphoric acid for several phosphonate ester adducts of chymotrypsin and in no case did the resonance for the adduct shift further downfield in the course of the experiments. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050307
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  • 80
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    Chiral resolution of some antimalarial agents by sub- and supercritical fluid chromatography on an (S)-naphthylurea stationary phase (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 173-180 
    Details
    ISSN: 0899-0042
    Keywords: (S)-naphthylurea chiral stationary phase ; subcritical fluid chromatography ; supercritical fluid chromatography ; antimalarial agents ; enantiomeric separations ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The behavior of mefloquine, halofantrine, enpiroline, quinine, quinidine, chloroquine and primaquine is studied by subcritical fluid chromatography on a (S)-naphthylurea column (250 mm × 4.6 mm ID) with a subcritical mobile phase composed of carbon dioxide, methanol and triethylamine (flow rate of 3 ml/min). Except for primaquine and chloroquine, each enantiomer was separated at a temperature between 40 and 60°C, and at a pressure below 15 MPa. A 98/2, v/v CO2/methanol 0.1% triethylamine mixture allowed the separation of halofantrine enantiomers while the enantiomers of the more polar metabolite (N-desbutylhalofantrine) were separated with a 80-20 v/v mixture as used for mefloquine, enpiroline, quinine and quinidine. The influence of temperature, pressure and of the nature of the mobile phase is discussed. © 1993 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050313
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  • 81
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    Announcement (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 199-199 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050317
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  • 82
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    Chiral stationary phases in concert with homologous chiral mobile phase additives: Push/pull model (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 201-206 
    Details
    ISSN: 0899-0042
    Keywords: enantiomer ; racemates ; separations ; chiral homology ; synergism ; push/pull model ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new “push/pull” model has been developed to explain synergistic effects observed in a system in which a chiral stationary phase (CSP) is used in combination with its homologous chiral mobile phase additive (CMPA). The model predicts the beneficial CMPA enantiomer and the counterproductive CMPA enantiomer a priori. Thus, an (R)-CSP will obtain positive synergism from a homologous (S)-CMPA and negative synergism from a homologous (R)-CMPA. The reverse is true for an (S)-CSP. The importance of structural homology between the CSP and the CMPA is demonstrated. Furthermore, the analysis time is decreased relative to the use of a CSP alone, because the retention time of the analyte peaks decreases when the CMPAs are used. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050402
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  • 83
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    Quantification of trace levels of β-cyclodextrin and substitution patterns in hydroxypropyl-β-cyclodextrin using high-performance liquid chromatography with polarimetric detection (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 220-223 
    Details
    ISSN: 0899-0042
    Keywords: hydroxypropyl-β-cyclodextrin ; cyclodextrin ; polarimetric detection ; optical rotation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A high-performance liquid chromatographic (HPLC) method has been developed for separation and determination of components in hydroxypropyl-β-cyclodextrin (HP-β-CD). The method involves separation on an amino-bonded HPLC column using water-acetonitrile as a mobile phase with a polarimetric HPLC detector for quantification. It provides good selectivity and sensitivity and can also be used to compare different sources of HP-β-CD and to measure batch to batch variation. The similarity of the values of molar optical rotation for β-cyclodextrin (β-CD) and HP-β-CD suggests that a polarimetric HPLC detector may be used with a straightforward area normalization method, to quantify the proportion of β-CD in any HP-β-CD sample. Trace amounts of β-CD in HP-β-CD have been measured to a precision of 0.01%. © 1993 Wiley-Liss, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050405
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  • 84
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    Benzoylcellulose derivatives as chiral stationary phases for open tubular column chromatography (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 232-237 
    Details
    ISSN: 0899-0042
    Keywords: enantiomer ; supercritical fluid chromatography (SFC) ; gas chromatography (GC) ; resolution ; polymer ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The application of cellulose-based stationary phases for chiral separations has been extended to open tubular column chromatography. Efficient columns were obtained by coating the capillaries with mixtures of chiral cellulose materials and conventional achiral stationary phases for gas chromatography. In this study, various siloxane and polyethylene glycol polymers were used as achiral components and mixed with different substituted benzoylcellulose derivatives as chiral components. Systematic investigations were carried out to determine the optimal ratio for the components of the stationary phase. Depending on the chromatographic mode - gas chromatography (GC) or supercritical fluid chromatography (SFC) - the stationary phases were found to behave differently. The applicability of the technique was demonstrated by the resolution of various racemic compounds. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050408
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  • 85
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    Preparative separation of amino acid enantiomers as N-TFA, O-isopropyl derivatives by continuous countercurrent gas-liquid chromatography (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 246-249 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; countercurrent gas-liquid chromatography ; preparative separation ; amino acid derivatives ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preparative separation of derivatives of amino acid enantiomers was carried out by a countercurrent gas-liquid chromatography (CCGLC) with chiral liquid phases, N-stearoyl-L-valine tert-butylamide and/or N-stearoyl-L-leucine tert-butylamide. In order to make effective use of these phases and also to lower the viscosity, Apiezon C was added as diluent. Through a repeated operation of a temperature gradient, purities more than 99% of leucine and α-amino butyric acid derivatives were proved to be obtained. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050411
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  • 86
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    Use of cyclodextrins as chiral selectors for direct resolution of the enantiomers of fluoxetine and its metabolite norfluoxetine by HPLC (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 258-266 
    Details
    ISSN: 0899-0042
    Keywords: β-cyclodextrin ; enantiomeric separation ; pH effects ; ionic strength effects ; flow rate effects ; solvent selectivity ; optimization ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The goal of this work is to investigate the direct chromatographic separation of the enantiomers of fluoxetine and its active metabolite norfluoxetine. The liquid chromatographic retention behavior of these enantiomers on a β-cyclodextrin bonded-phase column was investigated with respect to mobile phase composition, pH, ionic strength, and solvent selectivity. Relationships were established between these factors and the three most important chromatographic parameters: retention time, resolution, and selectivity. Most of the evidence suggests that the unique selectivity of this column isdue to inclusion complex formation, which provides the physical basis for enantiomeric resolution. After these studies a set of optimum chromatographic conditions was chosen for the simultaneous separation/determination of a mixture of the four enantiomers using fluorescence detector. © 1993 Wiley-Liss, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050414
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  • 87
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    Helical stereochemistry and chiral apple halves. 2. La coupe du roi via double helical complexation using oligo(bipyridine) strands and Cu(I)/Ag(I) (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 272-276 
    Details
    ISSN: 0899-0042
    Keywords: chirality ; helical stereochemistry ; la coupe du roi ; chiral recognition ; chiral polysectioning ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oligo(bipyridine) strands and Cu(I)/Ag(I) form duplexes having a 21-screw coincidental with a C2-axis. A segment containing a complete turn of the duplex can be considered to be a coupe du roi ensemble of two homochiral strands. Moreover, for D2d symmetry monocationic Cu(I) complexes of bipyridine trimers and pentamers, addition of the requisite Cu(I) cations is a true chemical example of la coupe du roi. In this reaction, an achiral monocationic complex is converted into a multiple-cationic duplex of two homochiral and homotopic 21-helical halves. The chirality of the resulting duplex is a function of the particular set of bipyridine enantiotopic faces which are used for binding the additional cations. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050416
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  • 88
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    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993) 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050501
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  • 89
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    HPLC separation of the enantiomers of nicotine and nicotine-like compounds (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 300-302 
    Details
    ISSN: 0899-0042
    Keywords: chiral separation ; α1-acid glycoprotein (AGP) ; nornicotine ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive and reproducible HPLC method utilizing a commercially available chiral α1-acid glycoprotein (AGP) phase has been developed to separate and quantify the enantiomers of nicotine. The method is suitable for routine use as indicated by column life. The quantification of (R/S:0.05/99.95)-nicotine or (R/S:99/1)-nicotine was possible. In addition, the separation or at least partial separation of the enantiomers of nornicotine and nornicotine-derived compounds was achieved. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050504
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  • 90
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    Influence of specific albumin ligand markers used as modifiers on the separation of benzodiazepine enantiomers by chiral liquid chromatography on a human serum albumin column (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 71-77 
    Details
    ISSN: 0899-0042
    Keywords: chiral stationary phase ; mobile phase modifier ; digoxin ; warfarin ; medium chain fatty acid ; bilirubin ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Specific ligand markers for the various binding sites of human serum albumin (HSA) have been described in the literature. Some of these markers (medium chain fatty acids, warfarin, digoxin, and bilirubin) were used as mobile phase modifiers. Using a high performance liquid chromatographic (HPLC) column containing HSA as stationary phase, their influence was investigated on the separation in this phase of the enantiomers of three benzodiazepines (temazepam, oxazepam, and lorazepam). Displacement effects were observed with medium chain fatty acids. This influence was proportional to the chain length and to the concentration of acid. Allosteric cooperative effects were noted with digoxin for the three benzodiazepines. Both displacement and cooperative effects were observed with warfarin. Stereoselectivity was decreased for temazepam and oxazepam and increased for lorazepam. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050206
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  • 91
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    Erratum (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 102-102 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050211
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  • 92
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    Announcement (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 104-104 
    Details
    ISSN: 0899-0042
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050213
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  • 93
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    Stereoselective protein binding of ketoprofen: Effect of albumin concentration and of the biological system (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 126-134 
    Details
    ISSN: 0899-0042
    Keywords: NSAID ; chirality ; enantiomers ; protein binding ; equilibrium dialysis ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Equilibrium dialysis was used to study in vitro the enantioselective binding of R, S, and racemic ketoprofen at physiological pH and temperature in human serum albumin (HSA) (1, 20, and 40 g/liter) and in plasma. The binding of enantiomers in a racemic mixture was studied to see the effect of each isomer on the other's interaction with the protein. The free fractions were determined by high-performance liquid chromatography. The binding of ketoprofen enantiomers to albumin was enantioselective, depending on both drug and protein concentrations. Enantioselectivity was observed in plasma too but was the opposite of that in HSA at 40 g/liter. The percentage of each isomer unbound was higher in the racemic mixture than with the isomer alone. The displacement of probes specific for HSA sites I and II, studied by spectrofluorimetry, suggests that all three preparations of ketoprofen are bound mainly to site I and secondarily to site II. © 1993 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050305
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  • 94
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    N-Acetyl-D and L-esters of 5′-AMP hydrolyze at different rates (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 150-153 
    Details
    ISSN: 0899-0042
    Keywords: aminoacyl adenylate esters ; hydrolytic stabilization by intramolecular interaction ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies of the properties of aminoacyl derivatives of 5′-AMP are aimed at understanding the origin of the process of protein synthesis. Aminoacyl (2′,3′) esters of 5′-AMP can serve as models of the 3′-terminus of aminoacyl tRNA. We report here on the relative rates of hydrolysis of AC-D- and L-Phe AMP esters as a function of pH. At all pHs above 3, the rate constant of hydrolysis of the AC-L-Phe ester is 1.7 to 2.1 times that of AC-D-Phe ester. The D-isomer seems partially protected from hydrolysis by a stronger association with the adenine ring of the 5′-AMP. © 1993 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050308
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  • 95
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    Enantioselective lipase-catalyzed ester hydrolysis: Effects on rates and enantioselectivity from a variation of the ester structure (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 154-158 
    Details
    ISSN: 0899-0042
    Keywords: enantioselective hydrolysis ; lipase ; esters ; substituent effects ; chiral liquid chromatography ; enantiomer separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to make a preliminary study of substituent effects on the rate and enantioselectivity obtained in esterolytic reactions catalyzed by a lipase from Candida rugosa, a series of racemic esters, derived from some α-alkyl and α-halo phenylacetic acids, were prepared. The reactions were studied at pH 6.0 and 50°C under which conditions uncatalyzed hydrolysis was relatively slow. Reaction samples were studied at different points of time by means of analytical chiral reversed-phase liquid chromatography, which permitted the simultaneous determination of product enantiomeric excess and of the degree of total ester hydrolysis. These data were then used to calculate initial rates as well as enantioselectivity. An increase of the steric bulk of the α-substituent was found to highly decrease the rate of the reaction. On the other hand, rates were higher for the p-nitrophenyl esters than for the corresponding 2-chloroethyl esters. Consistently, the enantioselectivity was found to be higher for the latter type of ester. The esters of the α-halo (bromo and chloro) phenylacetic acids gave mandelic acid as the final product. This was caused by a rapid solvolysis of the α-halo phenylacetic acid initially formed. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050309
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  • 96
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    Use of chiral β-lactones for the synthesis of chiral LC phases (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 168-172 
    Details
    ISSN: 0899-0042
    Keywords: chiral stationary phase ; chiral 2-oxetanone ; TLC ; SFC ; preparative LC ; push-pull chromatography ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Chiral β-lactones offer an easy and economic approach to novel chiral R- or S-configurated LC phases. The preferred method for their preparation is based on conventional ready-to-use aminopropyl-functionalized silicas, e.g., aminopropyl HPLC columns. The new stationary phases can be used for analytical and preparative separations and are particularly suitable for the resolution of rotatory and heterocyclic stereoisomers. Applications in the LC, SFC, and TLC mode are possible, including the use of β-lactone-based mobile phase additives in a “push-pull” combination. A large variety of organic solvents can be used as eluents. © 1993 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050312
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  • 97
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    Determination of the enantiomeric purity of 5,6- and 6,7-dihydroxy-2-aminotetralins by chiral HPLC (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 181-187 
    Details
    ISSN: 0899-0042
    Keywords: enantiomers ; direct separation ; 2-aminotetralins ; dopamine receptor agonist ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5,6- and 6,7-Dihydroxy-2-aminotetralin (ADTN), racemic dopamine receptor agonists, were resolved into their enantiomers by a new chiral HPLC assay. The separation was performed on a Crownpack CR column, which contains an 18-crown-6-type chiral crown ether as a chiral selector. The chiral recognition is based on the compiexation of the protonated primary amino group and the oxygen atoms inside the cavity of the crown ether. The amino group is attached to the chiral centre and therefore these compounds could be resolved. Mobile phase was perchloric acid pH 2.0 and the detection was UV at 200 nm. Resolution factors were 3.1 for 5,6-ADTN and 1.1 for 6,7-ADTN resulting in very low limits of quantitation (〈0.1%) of the enantiomer present as impurity. Data on the validation of the assay and on the stability of the column are also reported. © 1993 Wiley-Liss, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050314
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  • 98
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    Chirality of amino acids of microorganisms used in food biotechnology (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 385-392 
    Details
    ISSN: 0899-0042
    Keywords: D-amino acids ; bacterial starter cultures ; amino acid racemases ; nutrition ; gas chromatography ; chiral stationary phases ; Chirasil-Val ; Lipodex ; cyclodextrins ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Bacteria of the genera Acetobacter, Bifidobacterium, Brevibacterium, Lactobacillus, Micrococcus, Propionibacterium, and Streptococcus, which are used as so-called starter cultures for the large-scale production of fermented foods and beverages in food biotechnology, have been investigated for the chirality of their amino acids (AA) by gas chromatography (GC). Bacteria were grown in complex media, centrifuged, and washed with 0.85% aqueous NaCl. Aliquots were totally hydrolyzed (6 M HCl, 110°C, 18 h), or extracted with 70% aqueous ethanol in order to isolated free AA. The AA were adsorbed on Dowex WX 8 cation-exchanger, eluted with 4 M ammonia and converted into their N(O)-trifluoroacetyl(TFA) 2-propyl esters or TFA methyl esters. The AA derivatives were investigated by capillary GC using the chiral stationary phases Chirasil-L-Val, Chirasil-D-Val, and Lipodex E. Besides L-AA, in all bacteria D-amino acids (D-AA) were detected; those in the highest relative amounts were D-Ala and D-Asp (occurring in all bacteria) and, in several cases, D-Glu. Lower, but significant amounts of other D-AA such as D-Ser, D-Pro, D-Val, D-Thr, D-Ile, D-Leu, D-Met, D-Phe, D-Tyr, D-Orn, and D-Lys were also detected in certain bacteria. These findings explain the origin of D-AA found in all fermented foods and drinks produced with the aid of bacterial starter cultures. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/chir.530050521
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  • 99
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    Stereoselective and isozyme-selective drug interactions (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 407-413 
    Details
    ISSN: 0899-0042
    Keywords: stereoselecting ; drug metabolism ; drug interactions ; cytochrome P-45 ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A surprisingly large number of marketed drugs are racemic mixtures. The pharmacokinetic literature on racemic drugs contains a vast amount of information on drug-drug interactions derived from the measurement of total drug concentrations in plasma and urine. The appreciation of the role of stereochemistry in drug interactions with racemic warfarin resulted in a long-overdue scientific rigor being applied to the study of drug interactions. It also compelled us to recognize that much of the literature was uninterpretable. A better understanding of oxidative metabolism, particularly the complexity of the cytochrome P-450 family of enzymes, has also strengthened the scientific basis of drug interactions. We now recognize that investigators and clinicians must consider both stereoselectivity and isozyme selectivity in the study of drug interactions to understand the nature of the interaction so as to more effectively use new and potent drugs. © 1993 Wiley-Liss, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050603
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  • 100
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    Stereoselectivity of biliary excretion of 2-arylpropionates in rats (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 422-427 
    Details
    ISSN: 0899-0042
    Keywords: 2-arylpropionates ; enantiomers ; stereoselectivity ; chiral inversion ; pharmacokinetics ; bile-duct cannulated rats ; biliary excretion ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To examine the stereoselectivity of biliary excretion, the optically pure enantiomers of ketoprofen (KT), ibuprofen (IBU), and flurbiprofen (FLU) were intravenously administered to normal and bile duct-cannulated rats at 10 mg/kg. The recovery of total KT in bile was significantly higher after administration of (S)-KT than after (R)-KT [90.1 ± 3.5% vs 68.8 ± 8.2%, n =3, P 〈 0.05]. In normal rats the terminal half-life of (R)-KT was significantly shorter than that of (S)-KT after administration of (R)-KT (2.2 ± 0.6 h vs 14.3 ± 4.9 h, n = 3, P 〈 0.05). The terminal half-life of both enantiomers was significantly shorter in rats with continuous bile drainage as compared to normal rats. No significant differences in pharmacokinetic parameters could be found between both enantiomers in bile duct-cannulated animals. The total amount of IBU in bile was slightly higher after administration of (S)-IBU than after (R)-IBU administration. The percentage of (R)-IBU after (R)-IBU administration, however, was very low [(R)-IBU: 1.5 ± 0.9%, (S)-IBU: 23.4 ± 5.8%]. In normal rats the clearance of (R)-IBU was significantly higher as compared to (S)-IBU. Differences in pharmacokinetic parameters between normal and bile duct-cannulated rats were not statistically significant due to high interindividual variability. The total recovery of FLU, which was excreted in bile to a lower extent than either KT or IBU, also tended to be greater after S-enantiomer administration. Only small amounts of (S)-FLU could be recovered in bile after (R)-FLU administration. The pharmacokinetic parameters did not differ significantly between (R)- and (S)-FLU or between normal and bile duct-cannulated rats due to its low inversion rate and low excretion via bile. © 1993 Wiley-Liss, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050606
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