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  • 1
    Electronic Resource
    Electronic Resource
    A study of internal absorption in Zn(Cd)Se/ZnMgSSe semiconductor lasers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 2621-2626 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Based on two different experiments and an optical field calculation, we show that the free-carrier absorption αfc in Zn(Cd)Se/ZnMgSSe semiconductor lasers is about 4 cm−1 and that it is smaller than that of GaAs/AlGaAs semiconductor lasers. We have measured the dependence of the L-I characteristics on the cavity length of double heterostructure (DH) lasers under photopumped operation and of single quantum well-separate confinement heterostructure (SQW-SCH) lasers under current-injected operation. For the DH laser, the total absorption coefficient αi and β×J0 product (β is a gain constant, and J0 is the nominal current density that makes the gain equal to zero) are estimated to be 4.2 cm−1 and 8.6×10 cm−1, respectively. For the SQW-SCH laser, αi, β, and J0 are estimated to be 21 cm−1, 4.23×10−3 cm×μm/A, and 1.9×10−3 A/(cm2×μm), respectively. By calculating the optical fields of these lasers, we have estimated that the absorption in a GaAs substrate is 16.53 cm−1 in the SQW-SCH laser and that it is negligible in the DH laser. We have shown that the large loss in the SQW-SCH laser is caused by both αfc and the absorption in the substrate and that αi in the DH laser is caused only by free carrier absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.357558
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  • 2
    Electronic Resource
    Electronic Resource
    Structural Characteristics of Human Substantia Nigra Neuromelanin and Synthetic Dopamine Melanins (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Neuromelanin (NM) is a complex polymer pigment foundprimarily in the dopaminergic neurons of the human substantia nigra. Thestructure of NM is only partially characterized, and its synthesis pathwayremains unknown. We used nuclear magnetic and infrared spectroscopy to examinethe structure of human NM isolated from the substantia nigra compared withsynthetic dopamine melanins. Biochemical analyses were used to investigateproteinaceous and dopaminergic components in these samples. Following acidhydrolysis of NM samples, small amounts of DOPA, dopamine, and a variety ofamino acids were measured. These findings suggest a peptide component in NMstructure. NM also appears to contain a variety of unidentified structuralcomponents possibly derived from the oxidation of dopamine. Human NM differsstructurally from synthetic dopamine melanin, but both human and synthetic NMinclude an aromatic backbone. It is interesting that both human NM andsynthetic melanin also contain a large proportion of aliphatic structures. Ourresults suggest that NM is a more complex pigment than synthetic dopaminemelanin formed via dopamine autoxidation alone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0752583.x
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  • 3
    Electronic Resource
    Electronic Resource
    Inhibitory effects of cortical steroids and adrenocorticotropic hormone on catecholamine secretion in guinea-pig perfused adrenal glands (2002)
    Oxford, UK : Blackwell Science Ltd
    Autonomic & autacoid pharmacology 22 (2002), S. 0 
    Details
    ISSN: 1474-8673
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Chemistry and Pharmacology , Medicine
    Notes: 1 We investigated the effects of exogenously applied steroids and endogenously released cortisol on catecholamine (CA) secretion induced by cholinergic agonists in perfused guinea-pig adrenal glands. 2 Acetylcholine (ACh) and electrical stimulation induced CA secretion, which was reversibly inhibited by cortisol. Adrenocorticotropic hormone (ACTH) increased the concentration of cortisol in the perfusion effluent and partly inhibited the secretory response to ACh. 3 Cortisol or aldosterone dose-dependently inhibited secretory responses to nicotine and muscarine. These inhibitory effects were not antagonized by mifepristone and spironolactone, respective cortisol and aldosterone receptor blockers. 4 Dexamethasone, cortisone, corticosterone, 11-deoxycortisol, 11-deoxycorticosterone, prednisolone and cholesterol inhibited nicotine-evoked CA secretion. The secretory response to muscarine was inhibited by these compounds except for dexamethasone and prednisolone. 5 Dexamethasone, cortisol and aldosterone had no effect on CA secretion induced by high KCl. 6 These results suggest that steroids affect nicotinic and muscarinic ACh receptor-mediated responses through distinct mechanisms, and that cortisol released from the adrenal cortex inhibits CA secretion from the adrenal medulla.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1474-8673.2002.00246.x
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  • 4
    Electronic Resource
    Electronic Resource
    Impairment of gastrointestinal motility by nitrate administration: evaluation based on electrogastrographic changes and autonomic nerve activity (2004)
    Oxford, UK : Blackwell Publishing Ltd
    Alimentary pharmacology & therapeutics 20 (2004), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background : Nitrates decrease the tone of the lower oesophageal sphincter, and may thus induce gastro-oesophageal reflux.Aim : In the present study, we evaluated electrogastrographic changes and heart-rate variability before and after the administration of nitrates.Methods : In 15 patients with chest pain treated with nitrates, electrocardiography and percutaneous electrogastrography were performed before and after administration of nitrates. Autonomic nervous system function was evaluated by spectral analysis of heart-rate variability and serial changes in low frequency and high frequency power, and the low frequency/high frequency ratio were compared. Electrogastrograms were analysed by obtaining peak power amplitudes and their dominant frequencies.Results : After the administration of nitrates (isosorbide dinitrate), high frequency power, an index of parasympathetic nervous activity, was significantly decreased, whereas the low frequency/high frequency ratio, an index of sympathetic nervous activity, was significantly increased. The mean peak amplitude of the electrogastrogram significantly increased postprandially both before and after treatment. After isosorbide dinitrate treatment, however, mean peak amplitudes after a meal were significantly lower than those obtained before treatment. The mean dominant frequency of the electrogastrogram did not vary before and after treatment.Conclusions : The present study suggests that nitrates inhibit gastrointestinal motility by decreasing autonomic nervous activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2036.2004.01979.x
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  • 5
    Electronic Resource
    Electronic Resource
    Is autonomic dysfunction a necessary condition for chronic peptic ulcer formation? (2000)
    Oxford, UK : Blackwell Science Ltd
    Alimentary pharmacology & therapeutics 14 (2000), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background: The relationship between 1/f fluctuation of the heart rate variability and Helicobacter pylori infection was evaluated, in order to clarify whether autonomic nervous dysfunction is a necessary condition for chronic peptic ulcer formation. Methods: The subjects were 11 patients with recurrent chronic peptic ulcer and 20 age-matched normal subjects. Holter ECGs were recorded over 24 h, and the 1/f –x fluctuation of the heart rate was computed. The 1/f –x fluctuation of the heart rate is a novel index of autonomic function that has been shown to reflect a patient's pleasant mood. For 1/f –x fluctuation, the slope of the regression line (–x) was determined and cosine fitting of the absolute slope of the regression line over a 24-h period was performed. Results: For the normal group, the absolute slope of the regression line during daytime and night-time were 0.53 ± 0.16 and 1.05 ± 0.18, respectively. For the peptic ulcer group, the corresponding values during daytime and night-time were 0.94 ± 0.15 and 1.84 ± 0.18, respectively. The mean value of the cosine curve was 0.76 ± 0.23 in the normal group and 1.12 ± 0.25 in the peptic ulcer group. Thus, these values were significantly higher for the latter group than for the former group (P 〈 0.05). No statistically significant difference in H. pylori infection between the two groups was observed. Conclusions: Autonomic nervous dysfunction as well as H. pylori infection appears to be a necessary condition for chronic peptic ulcer formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.2000.014s1082.x
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  • 6
    Electronic Resource
    Electronic Resource
    Carbamazepine-induced hypersensitivity syndrome associated with transient hypogammaglobulinaemia and reactivation of human herpesvirus 6 infection demonstrated by real-time quantitative polymerase chain reaction (2003)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 149 (2003), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Drug-induced hypersensitivity syndrome (HS) is a rare but severe disease with multiorgan failure. Many different precipitating factors have been reported, but the pathophysiology of HS remains unknown. However, the association of the human herpesvirus (HHV) family, particularly of HHV-6, has recently been reported in patients with HS. We report a 14-year-old boy who was diagnosed as having carbamazepine-induced HS based on the clinical course, laboratory data and results of drug-induced lymphocyte stimulation tests. In addition, the reactivation of HHV-6 was demonstrated by real-time quantitative polymerase chain reaction and by significantly increased levels of the specific antibody in his paired sera. Furthermore, transient hypogammaglobulinaemia was detected in the early stage of the disease. In addition, serum levels of interferon-γ, interleukin (IL)-6, IL-5 and eosinophil cationic protein, which were increased on admission, decreased dramatically after steroid therapy. This is the first report of carbamazepine-induced HS associated with reactivation of HHV-6, transient hypogammaglobulinaemia, increased serum levels of inflammatory cytokines and activated eosinophils. This case might contribute to the understanding of the pathophysiology of HS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2003.05368.x
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  • 7
    Electronic Resource
    Electronic Resource
    Eumelanin and phaeomelanin contents of depigmented and repigmented skin in vitiligo patients (2003)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 149 (2003), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background There are two chemically distinct types of melanin: the red–yellow phaeomelanin and the brown–black eumelanin. Both types of melanin have been detected in human hair, epidermis and cultured melanocytes.Objectives In a preliminary study, to quantify levels of both eumelanin and phaeomelanin in depigmented as well as repigmented patches of vitiligo following psoralen plus ultraviolet A (PUVA) therapy.Methods We enrolled five patients with vitiligo for this study. We took biopsies from depigmented as well as repigmented lesions after PUVA therapy. The eumelanin and phaeomelanin contents of the skin biopsies were quantified by high-performance liquid chromatography.Results The mean concentrations in depigmented lesions were 229·4 ng per piece for phaeomelanin and 572 ng per piece for eumelanin (mean phaeomelanin/eumelanin ratio 0·36). In repigmented lesions, the mean concentration of phaeomelanin was 74·8 ng per piece and that of eumelanin was 1657·6 ng per piece (mean phaeomelanin/eumelanin ratio 0·049).Conclusions Depigmented lesions showed both types of melanin, and contained a substantial amount of phaeomelanin, whereas repigmented lesions after PUVA showed predominantly eumelanin. We detected melanin in depigmented lesions of vitiligo of 5 years duration, suggesting that some residual melanocytes are still active in depigmented lesions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2003.05440.x
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  • 8
    Electronic Resource
    Electronic Resource
    Autonomic nervous activity before and after eradication of Helicobacter pylori in patients with chronic duodenal ulcer (2002)
    Oxford UK : Blackwell Science Ltd.
    Alimentary pharmacology & therapeutics 16 (2002), S. 0 
    Details
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Helicobacter pylori infection is involved in the formation of chronic peptic ulcer. However, a previously reported hypothesis concerning the involvement of central autonomic nervous disorder in this condition cannot be ruled out.〈section xml:id="abs1-2"〉〈title type="main"〉Aim:To use spectrum analysis of heart rate viability to examine autonomic nervous activity before and after H. pylori eradication.〈section xml:id="abs1-3"〉〈title type="main"〉Methods:Twenty patients with chronic duodenal ulcer (duodenal ulcer group) and 20 age-matched normal adults (N group). In both groups, 24-h Holter electrocardiograms (ECGs) were recorded and spectrum analysis of heartrate variability was performed. In the duodenal ulcer group, Holter ECG was recorded before and after H. pylori eradication.〈section xml:id="abs1-4"〉〈title type="main"〉Results:In the N group, analysis of heart rate variability showed that high frequency (HF) power, an index of parasympathetic activity, was high at night, while the low frequency (LF)/HF ratio, an index of sympathetic function, was high during the daytime. In the duodenal ulcer group, HF power was higher at night than during the daytime, showing a similar pattern to the N group, but the power value was higher than in the N group (P 〈 0.05). In the duodenal ulcer group, LF/HF at night was significantly higher than that of the N group. In addition, in the duodenal ulcer group, autonomic activity after H. pylori eradication did not differ significantly from that before H. pylori eradication.〈section xml:id="abs1-5"〉〈title type="main"〉Conclusions:In patients with chronic peptic ulcer, both sympatheticotonia and parasympatheticotonia may occur at night, and this abnormality in autonomic nervous activity may cause increased gastric acid secretion and gastric mucosal vasoconstriction. Abnormalities in autonomic activity persist even after H. pylori eradication, suggesting that they may be an independent risk factor in the formation of chronic peptic ulcer in addition to H. pylori infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2036.16.s2.27.x
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  • 9
    Electronic Resource
    Electronic Resource
    Stevens–Johnson syndrome associated with azithromycin followed by transient reactivation of herpes simplex virus infection (2004)
    Oxford, UK : Munksgaard International Publishers
    Allergy 59 (2004), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1398-9995.2003.00336.x
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  • 10
    Electronic Resource
    Electronic Resource
    L-Homocysteate Preferentially Activates N-methyl-D-aspartate Receptors to CA1 Rat Hippocampal Neurons (1991)
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 3 (1991), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Intracellular recordings and current and single-electrode voltage-clamp techniques were used to study the membrane responses of CA1 pyramidal neurons to bath application of L-homocysteic acid (L-HC) in the rat hippocampal slice preparation. In control artificial cerebrospinal fluid (ACSF), L-HC (25 - 250 μM) depolarized the membrane and induced a burst-like firing pattern. Both the membrane depolarization and the burst firing were blocked by the N-methyl-D-aspartic acid (NMDA) receptor antagonists D-(-)-2-amino-5-phosphonovaleric acid (AP-5, 50 μM), D-(-)-2-amino-7-phosphonoheptanoic acid (AP-7, 50 μM) and (±)-3-(2-carboxy-pipera-zin-4-yl)-propyl-1-phosphonic acid (CPP, 20 μM). In ACSF containing tetrodotoxin (1 μM), L-HC (100–300 μM) induced at resting membrane potential a depolarization which was associated with a small increase in input conductance. These effects were unaffected by 6-cyano-7-nitroquinoxaline-2, 3-dione (CNQX, 10–20 μM) but were fully blocked by AP-5, AP-7 (50 μM) and CPP (10–20 μM). In voltage-clamp experiments, L-HC induced slow inward currents which were voltage-dependent between - 70 and - 30 mV and reversed polarity near 0 mV. The L-HC-induced inward current was unaffected by CNQX (10–20 μM) but was strongly reduced by AP-5 or AP-7 (50 μM). The L-HC-induced inward current was temperature-dependent. Between -60 and -70 mV, its amplitude increased by 320% when the temperature was lowered from 33 to 22°C. The L-HC-induced current was also potentiated by the specific L-HC uptake blocker β-p-chlorophenylglutamate (Chlorpheg, 0.5–2 mM). These data suggest that L-HC preferentially activates NMDA receptors in CA1 hippocampal neurons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1460-9568.1991.tb00032.x
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