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201.
Zimmermann RC; Krahn L; Rahmanie N; Sauer MV 《Human reproduction (Oxford, England)》1998,13(4):822-825
Leptin has been called a hormone of reproduction, and seems to link fat and
fertility. It has been speculated that the neurotransmitter norepinephrine
(NE) (noradrenaline), possibly via the sympathetic nervous system, may
represent the afferent signal which modulates leptin release from
adipocytes. The purpose of this study was to produce a state of decreased
sympathetic output by using the catecholamine synthesis inhibitor
alpha-methyl-para-tyrosine (AMPT), in order to study the effect of this
compound on the secretion of leptin from fat cells. Ten subjects (five
women and five men) received a total of 5 x 1 g doses of AMPT or 5 x 50 mg
promethazine (active placebo) over a 26 h period, separated by 4-6 weeks
using a randomized, double- blind, placebo-controlled, cross-over design.
Blood samples for hormone measurements were obtained over 24 h (18 time
points) on day 2 of each experiment. Urinary measurement of the NE
metabolite 3-methoxy-4- hydroxyphenylglycol (MHPG) on study day 2 served as
a marker of the effectiveness of AMPT as an inhibitor of NE synthesis. The
daily excretion of this metabolite decreased from 1.56 +/- 0.22 mg in the
placebo experiment to 0.53 +/- 0.1 mg in the active experiment (P <
0.05). Plasma leptin concentrations measured in the control group in women
and men were similar to those reported previously in lean subjects with a
body mass index < 27.5 kg/m2. Leptin concentrations in women were 3-fold
higher than in men. Leptin is secreted in a circadian rhythm in both sexes
with an increase of nocturnal concentrations by approximately 50%. Two-way
analysis of variance reveals no significant difference in leptin secretion
between the control and active groups in women and men. In summary,
preliminary results do not support the hypothesis that NE represents the
afferent signal from the central nervous system which modulates leptin
release from adipocytes in the human. Further studies are needed to define
the role of the sympathetic nervous system as well as NE in the regulation
of leptin secretion and its involvement in obesity and reproduction.
相似文献
202.
The spontaneous disappearance of the inhibitor to factor VIII (FVIII) was observed in two human immunodeficiency virus (HIV)-infected men with hemophilia A. Both men had end-stage HIV infection, one with acquired immune deficiency syndrome (AIDS) and one with severe AIDS-related complex (ARC). Loss of the inhibitor was associated with a fall in T4 helper lymphocytes to less than 100 per mm3 in both patients. Subsequent spontaneous and traumatic hemorrhages were treated successfully with standard doses of FVIII concentrate, resulting in adequate FVIII:C levels and good hemostasis. The mechanism by which the anti-FVIII inhibitor disappears is not known, but it is likely to be related to a quantitative decline in T4 cell number. 相似文献
203.
Cell-lineage antigens of the stem cell-megakaryocyte-platelet lineage are associated with the platelet IIb-IIIa glycoprotein complex 总被引:5,自引:2,他引:3
The stem cell-platelet lineage is uniquely defined by platelet cell- lineage antigens. These antigens are present on all stem cells measured by the spleen colony assay and become restricted to the platelet cell lineage as differentiation proceeds. In this study, anti-platelet serum (APS) has been used to identify cells in the bone marrow that express platelet cell-lineage antigens and to identify platelet cell surface molecules expressing these antigens. Anti-platelet IgG extensively absorbed with brain, thymus, and peritoneal cells bound selectively to stem cells, megakaryocyte progenitor cells (Mk-CFC), and megakaryocytes in CBA mouse bone marrow and to blood platelets. No other hemopoietic cell type, tissue, cell line, or tumor cell bound significant amounts of antibody against platelet cell-lineage antigens as determined by ability to absorb the anti-stem cell activity in APS. Studies with lactoperoxidase-labeled platelets showed that two major iodinated proteins of Mr = 114,000 and 138,000 were immunoprecipitated with APS and with antiserum that had been extensively absorbed. These proteins correspond to the platelet IIb-IIIa glycoprotein complex, which is known to express receptors for collagen and fibrinogen, molecules known to influence hemopoietic cell proliferation and tumor cell growth. A panel of six monoclonal antibodies against human IIb-IIIa inhibited spleen colony formation by 17% to 100%, J15 and A5.15 also being cytotoxic for granulocyte-macrophage progenitor cells and Mk-CFC. Other platelet monoclonal antibodies did not inhibit spleen colony formation. Although APS inhibited fibrinogen binding to platelets and platelet aggregation, these activities were greatly reduced with absorbed antiserum. Furthermore, fibrinogen treatment of bone marrow did not block the anti-stem cell activity in APS. Thus the evidence is consistent with expression of platelet cell-lineage antigens on the platelet IIb-IIIa glycoprotein complex at a site removed from the fibrinogen binding site. 相似文献
204.
Metabolic activation of aromatic amines by human pancreas 总被引:4,自引:3,他引:4
Anderson KE; Hammons GJ; Kadlubar FF; Potter JD; Kaderlik KR; Ilett KF; Minchin RF; Teitel CH; Chou HC; Martin MV; Guengerich FP; Barone GW; Lang NP; Peterson LA 《Carcinogenesis》1997,18(5):1085-1092
Epidemiologic studies have suggested that aromatic amines (and
nitroaromatic hydrocarbons) may be carcinogenic for human pancreas.
Pancreatic tissues from 29 organ donors (13 smokers, 16 non-smokers) were
examined for their ability to metabolize aromatic amines and other
carcinogens. Microsomes showed no activity for cytochrome P450 (P450)
1A2-dependent N-oxidation of 4-aminobiphenyl (ABP) or for the following
activities (and associated P450s): aminopyrine N-demethylation and
ethylmorphine N-demethylation (P450 3A4); ethoxyresorufin O- deethylation
(P450 1A1) and pentoxyresorufin O-dealkylation (P450 2B6); p-nitrophenol
hydroxylation and N-nitrosodimethyl-amine N-demethylation (P450 2E1);
lauric acid omega-hydroxylation (P450 4A1); and 4-
(methylnitrosamino)-1-(3-pyridyl-1-butanol) (NNAL) and 4-
(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) alpha-oxidation (P450
1A2, 2A6, 2D6). Antibodies were used to examine microsomal levels of P450
1A2, 2A6, 2C8/9/18/19, 2E1, 2D6, and 3A3/4/5/7 and epoxide hydrolase.
Immunoblots detected only epoxide hydrolase at low levels; P450 levels were
<1% of liver. Microsomal benzidine/prostaglandin hydroperoxidation
activity was low. In pancreatic cytosols and microsomes, 4-nitrobiphenyl
reductase activities were present at levels comparable to human liver. The
O-acetyltransferase activity (AcCoA- dependent DNA-binding of
[3H]N-hydroxy-ABP) of pancreatic cytosols was high, about twothirds the
levels measured in human colon. Cytosols showed high activity for
N-acetylation of p-aminobenzoic acid, but not of sulfamethazine, indicating
that acetyltransferase-1 (NAT1) is predominantly expressed in this tissue.
Cytosolic sulfotransferase was detected at low levels. Using
32P-post-labeling enhanced by butanol extraction, putative arylamine-DNA
adducts were detected in most samples. Moreover, in eight of 29 DNA
samples, a major adduct was observed that was chromatographically identical
to the predominant ABP- DNA adduct, N-(deoxyguanosin-8-yl)-ABP. These
results are consistent with a hypothesis that aromatic amines and
nitroaromatic hydrocarbons may be involved in the etiology of human
pancreatic cancer.
相似文献
205.
206.
FA Almeida MV Pavan CIS Rodrigues 《BJOG : an international journal of obstetrics and gynaecology》2009,116(13):1749-1754
Objective To characterise the haemodynamic, renal-electrolyte and hormonal parameters in normal near-term pregnancy.
Design Observational prospective case-series study.
Setting and population Eleven women with normal pregnancies at 35–39 weeks gestation.
Methods Following baseline laboratory assessments and placement of a right-atrial catheter, serial measurements were obtained for 2 hours in the supine position (SP) followed by a change to the (LLP) and subsequent observations for 2 hours.
Main outcome measures Blood pressure (BP), central venous pressure (CVP), atrial natriuretic peptide (ANP), plasma renin activity (PRA), plasma aldosterone (ALDO), diuresis, creatinine clearance, sodium and potassium excretion.
Results In the SP, the subjects' BP remained stable while their CVP decreased. In the LLP, the subjects' systolic and diastolic BP consistently decreased by about 15 mmHg and their CVP increased within the first 60 minutes. ANP levels doubled in the subjects while they rested in the LLP, whereas the subjects' PRA and ALDO levels decreased by half compared with when they rested in the SP. In the LLP, the subjects' creatinine clearance significantly increased by 12% and their sodium excretion and diuresis increased by 38% and 59% respectively.
Conclusion Rest in the LLP induces systemic and intra-renal haemodynamic and hormonal changes that may play a central physiological role in the renal excretory response to restore excessive sodium/water retention in late pregnancy. 相似文献
Design Observational prospective case-series study.
Setting and population Eleven women with normal pregnancies at 35–39 weeks gestation.
Methods Following baseline laboratory assessments and placement of a right-atrial catheter, serial measurements were obtained for 2 hours in the supine position (SP) followed by a change to the (LLP) and subsequent observations for 2 hours.
Main outcome measures Blood pressure (BP), central venous pressure (CVP), atrial natriuretic peptide (ANP), plasma renin activity (PRA), plasma aldosterone (ALDO), diuresis, creatinine clearance, sodium and potassium excretion.
Results In the SP, the subjects' BP remained stable while their CVP decreased. In the LLP, the subjects' systolic and diastolic BP consistently decreased by about 15 mmHg and their CVP increased within the first 60 minutes. ANP levels doubled in the subjects while they rested in the LLP, whereas the subjects' PRA and ALDO levels decreased by half compared with when they rested in the SP. In the LLP, the subjects' creatinine clearance significantly increased by 12% and their sodium excretion and diuresis increased by 38% and 59% respectively.
Conclusion Rest in the LLP induces systemic and intra-renal haemodynamic and hormonal changes that may play a central physiological role in the renal excretory response to restore excessive sodium/water retention in late pregnancy. 相似文献
207.
Hepatic stellate cells and the reversal of fibrosis 总被引:2,自引:0,他引:2
208.
209.
Liu Q Liu R Kashyap MV Agarwal R Shi X Wang CC Yang SH 《中国神经肿瘤杂志》2009,7(3):203-203
OBJECT: Brainstem gliomas are common in children and have the worst prognosis of any brain tumor in this age group. On the other hand, brainstem gliomas are rare in adults, and the authors of some clinical studies have suggested that this lesion behaves dif ferently in adults than in children. In the present study, the authors test an orthotopic C6 brainstem glioma model in juvenile and adult rats, and investigate the biological behavior of this lesion in the 2 age groups. METHODS: The C6 glioma cells were stereotacti eally implanted into the pons of juvenile or adult male rats. Neurological presentation and survival time were recorded. 相似文献