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Biomedical subjects

D Durand

Publications and source records attributed to D Durand.

At least 379 records · Page 21Linked to original sources
PubMedDate not supplied

Daily metabolism and hepatic balance studies of plasma cortisol and aldosterone in the preruminant calf.

Intestinal and hepatic catabolism of cortisol and aldosterone were studied in the calf using blood samples from the mesenteric artery and portal and hepatic veins collected over 24 h, the hepatic blood flow being continuously recorded during this period. The total hepatic blood flow remained broadly constant over the 24 h, although meals were followed by decreasing flow in the portal vein and by increasing flow in the hepatic artery. The intestinal tract catabolizes cortisol as intensively as the liver (both 13% of cortisol reaching the organ). The part played by the gut and the liver in the catabolism of aldosterone were also equivalent (both 30% of aldosterone reaching the organ). This 24-h study demonstrated that a constant ratio existed between secretion and catabolism of cortisol while the hepatic balance of aldosterone seemed to be modified during the night.

Aldosterone↗
PubMedDate not supplied

Vasoactive intestinal peptide induces a transient release of growth hormone in the rat.

Effects of vasoactive intestinal peptide (VIP) on growth hormone (GH) secretion were investigated both in vivo on freely moving, intact or mediobasal hypothalamic lesioned rats, and in vitro in incubation or superfusion systems of anterior pituitary tissue. In vivo, IV injection of VIP induced a rapid but transient increase in plasma GH levels in all animals and in vitro, VIP stimulated GH release from incubated or superfused rat pituitaries in a concentration dependent manner. This increase was potentiated by forskolin, a potent activator of adenylate cyclase. These findings indicate that VIP exerts a direct stimulating action on somatotrophs and that the effect seems to imply a coupling of VIP receptors with cAMP production.

Animals↗
PubMedDate not supplied

Ex vivo flow cytometry determination of intracytoplasmic expression of IL-2, IL-6, IFN-gamma, and TNF-alpha in monocytes and T lymphocytes, in chronic hemodialysis patients.

AIMS: To determine the intracytoplasmic expression of TNF-alpha, IL-2, IL-6 and IFN-gamma, ex vivo and in vitro, in both monocytes and T lymphocytes by flow cytometry after appropriate stimulation using phorbol myristate acetate (PMA)/ionomycin or lipopolysaccharides (LPS) in the presence of monensin, in order to assess the bio(in)compatibility of different dialysis membranes. METHODS: We examined monocytes and T lymphocytes taken from chronic hemodialysis patients (using either cuprophane (CUP), n = 6; polyacrylonitrile (AN 69), n = 6; or polysulfone (PS), n = 6 membranes), before and after a dialysis session. We compared the results with those obtained from end-stage chronic renal failure patients (n = 3) and healthy volunteers (n = 11). RESULTS: Before any stimulation there was a statistically significant difference in the percentages of TNF-alpha, IL-6, and IFN-gamma- expressing monocytes with respect to the dialysis membrane used. The highest percentages were observed for CUP and AN69 patients with figures of around 30% for each cytokine; the lowest percentages were found in PS patients and healthy volunteers. One hour after LPS stimulation the patterns remained unchanged for TNF-alpha and IFN-gamma, whereas the percentages of IL-6-expressing cells in PS patients and in healthy volunteers reached the figures obtained in the other groups. When we examined the percentage of IFN-gamma-, TNF-alpha- and IL-6-expressing monocytes in patients before and after a dialysis session, before any stimulation, we found that the results were significantly different for the three membranes (p = 0.01). Thus, a dialysis session with polysulfone membranes had no significant effect on the precentages of IFN-gamma-, TNF-alpha-, and IL-6-expressing monocytes, whereas percentages were significantly lower after the dialysis session when using cuprophane or AN69 membranes, suggesting a release of these cytokines by the monocytes during dialysis. A significant number of IFN-gamma- and IL-2-expressing T lymphocytes were only detected after 18 hours of PMA/ionomycin stimulation. The percentages of IFN-gamma-expressing T cells recorded for the different membranes were not statistically different from those recorded for healthy subjects or pre-dialysis patients, i.e., they were between 11.5 and 20%. However, the percentages of IL-2-expressing T lymphocytes were significantly different between the 5 groups, i.e., 31.3, 30.5, 18.6, 13.9 and 7. 6%, respectively, for CUP patients, pre-dialysis patients, healthy volunteers, PS and AN69 patients. This suggests that pre-dialysis and CUP patients have, at baseline, a stimulation of their T lymphocytes. Finally, a 4-hour dialysis session had no impact on the percentages of IL-2-expressing T lymphocytes, whereas it was associated with a significant decrease in the percentage of IFN-gamma-expressing cells, but only when cuprophane membranes were used. CONCLUSION: Cytokine flow cytometry enables one to study, ex vivo, i.e., without any stimulation of the cells, and in vitro after appropriate stimulation, the bio(in)compatibility of dialysis membranes assessed by the intracytoplasmic cytokine profiles of TNF-alpha, IFN-gamma, IL-6 and IL-2, evaluated at the single cell level.

Adult↗
PubMedDate not supplied

Lack of effect of chronic hepatitis C virus infection on T-cell cytokine production in chronic hemodialysis patients.

It has been shown that chronic hemodialysis modifies, to some extent, the normal immune response by both T and B lymphocytes elicited by antigenic stimulation, e.g. by impairing the T-cell-dependent response after vaccination. A new technique, i.e. flow cytometry, enables to assess intracytoplasmically, at the single cell level, the production of a given cytokine. By using it, we studied in healthy volunteers (HV) and in chronic hemodialysis (CHD) patients, with respect to their hepatitis C virus (HCV) status, the production by the T lymphocytes of type 1, and type 2 cytokines. We studied the following cytokines (CK): IL-2, IL-4, IL-5, IL-6, IL-10, IFN-gamma and TNF-alpha in the T-cell lymphocytes (whole, CD4+ and CD8+). There were 13 HV and 59 CHD patients (36 HCV(-) and 23 HCV(+)). Amongst the latter, there were 32 men and 27 women, aged 59.5 +/- 2 years, undergoing CHD since 70 +/- 9.4 months. We found that: (1) the total number of lymphocytes as well as those expressing CD3, CD4, or CD19 were significantly decreased in CHD patients as compared to those from HV; (2) the total number of lymphocytes as well as their different subsets were similar in HCV(+) and in HCV(-) CHD patients; (3) the frequency of T-cell-expressing IL-5 or IL-10 was always low (<1%) in both HV and CHD groups; (4) overall in CHD patients, the mean percentages of T lymphocytes expressing IL-2, IL-4, IFN-gamma or TNF-alpha were respectively 31 +/- 13, 2.5 +/- 1.3, 28 +/- 12 and 34 +/- 11% and were not statistically different between HCV(+) and HCV(-) patients; (5) IL-2 was mainly produced by CD4+ T cells, whereas IFN-gamma was produced by CD8+ T cells, in both HV and CHD groups, and (6) the lymphocytes of CHD patients produced significantly more IL-2 and IL-4 than those from HV, suggesting an activation of their T lymphocytes. We conclude that using the cytokine flow cytometry assay, our study demonstrated that in HCV(+) CHD patients, as opposed to what has been described for HCV(+) patients with normal renal function, there was no impairment in the production of type 1 cytokines by peripheral blood mononuclear cells when compared to HCV(-) CHD patients. Conversely to HV, T lymphocytes from CHD patients are activated.

Adult↗
PubMedDate not supplied

[Apolipoprotein E and bleomycin hydrolase. Polymorphisms: association with neurodegenerative diseases].

Several studies indicate a possible association between different genes and chronic neurodegenerative diseases including Alzheimer's disease (DTA). To further investigate, we have analyzed association between the apolipoprotein E (apo E) and bleomycin hydrolase (BH) polymorphisms and three groups of elderly patients: control subjects (T) (n = 68), late-onset sporadic DTA patients (DTAst) (n = 65) and other non vascular neurodegerative diseases (MNDA) (n = 52). Apo E-epsilon4 and BH-G alleles frequencies (%) are: 8.2 (T), 31.5 (DTAst), 16.4 (MNDA) and 41.4 (T), 35.6 (DTAst). No association has been observed between carrying the G allele and DTA in epsilon4 negative subjects but, our data have confirmed the earlier reports: carrying the epsilon4 allele is a dose-dependent risk factor for the DTAst (OR: 6.0, IC 95 %: 2.6-13.7) and decrease the age of symptom onset (p < 0.005). They have also suggested that apo E genotyping may be of interest to perform differential diagnosis of neurodegenerative diseases in elderly subjects.

Aged↗
PubMedDate not supplied

Evolution of untreated mild rejection in heart transplant recipients.

To elucidate whether mild rejection requires treatment, we retrospectively examined the spontaneous natural history of this histologic feature without an increase of immunosuppression. During a 4-year period, 55 heart transplantations were performed in 54 patients on whom 958 endomyocardial biopsies were performed. Among these biopsies, 162 specimens showed features of mild rejection. We studied the results of subsequent biopsies performed 7 to 10 days later, without any change in immunosuppression. These revealed regression of lesions to minimal rejection in 51 cases (31%), the same histologic feature in 82 cases (51%), or progression to moderate or severe rejection in 29 cases (18%). In 82% of these cases, therefore, no aggravation of histologic feature was observed. We separated the cases in which current-study biopsies showed mild rejection into three groups according to the result of the most recent biopsy, that is, minimal, mild, or moderate-severe rejection. The percentage of good outcome was not modified by the nature of the previous biopsy specimen: 84%, if minimal rejection was preceding the study biopsy; 82%, in the cases of mild rejection; and 77%, for moderate or severe rejection. We did not find significant differences in this evolution between patients with fewer or more than two moderate or severe acute rejections in the first 4-month period after heart transplantation (respectively, 15% or 24% progression to moderate or severe acute rejection after nontreated mild rejection).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗