Philippe L. Selvais

Cardiac natriuretic peptides for diagnosis and risk stratification in heart failure: influences of left ventricular dysfunction and coronary artery disease on cardiac hormonal activation.

Cardiac natriuretic peptides are activated in heart failure. However, their diagnostic and prognostic values have not been compared under the routine conditions of an outpatient practice.

Role of Endogenous Endothelin-1 in Experimental Renal Hypertension in Dogs

BACKGROUND Endothelin-1, a vasoconstrictive peptide released by endothelium, may be involved in the pathophysiology of hypertension. The goal of the present study was to evaluate the role of endogenous endothelin-1 in renal hypertension in dogs. The model of hypertension consisted of silk tissue wrapping of the left kidney, which produced hypertension associated with perinephritis after 6 to 8 weeks. METHODS AND RESULTS Thirty-two anesthetized open chest dogs were studied randomly: 8 dogs with perinephritic hypertension received the nonpeptidic ETA-ETB receptor antagonist bosentan (group 1); 8 other hypertensive dogs received the vehicle solution (group 2); 8 healthy dogs received bosentan (group 3); and 8 healthy dogs received the vehicle solution (group 4). Bosentan was injected as an intravenous bolus (3 mg/kg) followed by a 1-hour infusion at a rate of 7 mg.kg-1.h-1. In hypertensive dogs, bosentan produced a similar decrease (P = .0001) of both left ventricular systolic and mean aortic pressures, which averaged 38 mm Hg (-22% and -24%, respectively). These parameters remained unchanged with the vehicle solution. Left ventricular end-diastolic and left atrial pressures also declined significantly with bosentan (P = .0005 and P < .05, respectively). Left ventricular lengths tended to decrease. The other cardiovascular parameters (heart rate, peak [+]dP/dt, time constant of relaxation, and coronary vascular resistance) did not change significantly. In healthy dogs, bosentan decreased mean aortic pressure by 19 mm Hg (P = .004). Vehicle solution had no effect. Plasma endothelin-1 levels, similar under basal conditions in healthy and hypertensive dogs, increased 30-fold with bosentan (P = .0001). CONCLUSIONS Specific endothelin-1 receptor antagonism markedly lowers blood pressure in experimental hypertension but is less effective on blood pressure of healthy animals. This suggests that endothelin-1 plays a role in the pathophysiology of hypertension but contributes to a lesser extent to the maintenance of normal blood pressure. This role of endothelin-1 is unrelated to its plasma levels. The increase of plasma endothelin-1 with bosentan, due either to a displacement of endothelin-1 from its receptor or to a feedback mechanism, does not prevent this blood pressure reduction.

Cyclic feeding behaviour and changes in hypothalamic galanin and neuropeptide Y gene expression induced by zinc deficiency in the rat.

Dietary zinc‐deficiency induces a striking reduction and a cyclic pattern of food intake in rodents. To elucidate the mechanisms for these effects, we studied the hypothalamic content, synthesis, and distribution of galanin (GAL) and neuropeptide Y (NPY) during zinc deficiency and refeeding in the rat. In Wistar rats, three weeks of zinc‐deprivation consistently induced a reduction and a cyclic pattern of night‐and day‐time food intake, as well as of water intake. This was accompanied in zinc‐deficient (ZD) rats, and to a lesser extent in pair‐fed (PF) rats, by a decrease of hypothalamic GAL mRNA concentration (CTR: 100±8, ZD: 61±4, PF: 78±2 arbitrary densitometric units, ADU, P<0.01) and an increase of hypothalamic NPY (CTR: 100±11, ZD: 154±10, PF: 126±4 ADU, P<0.05), without peptide modification. The two neuropeptidergic systems were not affected by the cycles of feeding, with the exception of the NPY‐immunoreactivity in the suprachiasmatic nuclei (geniculo‐hypothalamic tract), that was inversely correlated to the food intake in both ZD and PF animals. In a second experiment, we showed that zinc‐repletion for 4 days suppressed the behaviour induced by a two‐week zinc‐deprivation, and reversed the increase of NPY mRNA in ZD animals. We finally demonstrated that zinc‐deficiency induced a similar behaviour in Zucker rats. However, in these rats whose synthesis of NPY is constitutively up‐regulated, no change of NPY synthesis was observed in ZD rats, suggesting that the increase observed in Wistar is adaptative rather than instrumental to the abnormal food intake. In conclusion, we have further characterized the cyclic feeding behaviour of the zinc‐deficient Wistar rats, and shown in these animals a decreased activity of the GAL system and an increased activity of the NPY system, likely corresponding to a compensatory response of the two neuropeptidergic systems, as observed in food‐deprived animals. As spontaneous food intake of ZD rats does not increase, a resistance to NPY could also be present. These behavioural and neuropeptidergic changes were partially reversed by reintroduction of zinc in the diet. In Zucker rats, the same behaviour occurred despite an insensitivity of the NPY system to the zinc‐deficiency. In addition, we describe a nutritional regulation of the NPY‐immunoreactivity in the geniculo‐hypothalamic tract, that could constitute the substrate of circadian rhythm modulation by timed feeding.

Breast infiltration by acute lymphoblastic leukemia during pregnancy.

A case of bilateral breast infiltration as the initial manifestation of FAB-L3 leukemia during pregnancy is reported. This rare presentation is usually associated with Burkitts lymphoma or FAB-L3 leukemia. A high suspicion of the presence of hematologic malignancy and appropriate evaluation are indicated in the presence of this clinical manifestation.

Exenatide improves weight loss insulin sensitivity and β-cell function following administration to a type 2 diabetic HIV patient on antiretroviral therapy

The use of retroviral drugs in the treatment of infection by human immunodeficiency virus (HIV) is associated, especially for first generations, with side effects such as lipodystrophy, fatty liver and insulin resistance, which may trigger secondary diabetes or worsen existing diabetes. The use of Glucagon-Like Peptide-1 in obese patients with type 2 diabetes on HIV retroviral as an alternative to insulin therapy is not documented; we report the case of a 47-year-old treated with exenatide when insulin was discontinued. During the first year of treatment, exenatide, in combination with metformin and repaglinide, led to a weight loss of 14 kg and fat mass and waist circumference were respectively reduced from 31 to 25.5% and from 114 to 103 cm. Homeostatic model assessment (HOMA) was used to calculate β-cell secretion which increased from 50 to 78% and insulin sensitivity which increased from 28 to 51%, reflecting a decrease in HbA(1c) by 1.9%. Exenatide may be a new therapeutic option for HIV-infected type 2 diabetes patients undergoing retroviral therapy.

Effects of hypophysectomy on galaninergic neurons in the rat hypothalamus.

To understand better the relationship between hypothalamic galaninergic neurons and the pituitary gland, we studied the effects of hypophysectomy on hypothalamic galanin (GAL) content and distribution by radioimmunoassay and immunohistochemistry, and on GAL mRNA by Northern blot analysis. Three weeks after hypophysectomy, performed at 5 or 8 weeks of age, the hypothalamic concentrations of GAL and GAL mRNA were reduced by 30-50% in both male and female rats, compared to age- and sex-matched controls. Similar reverse-phase HPLC retention times of hypothalamic GAL were observed in intact and hypophysectomized rats. The reduction of hypothalamic GAL concentration following hypophysectomy was time-dependent, as peptide levels were unaffected one week after surgery. Immunohistochemistry showed regional differences in the effect of hypophysectomy on galaninergic neurons. In the hypophysiotropic hypothalamus, the scarce GAL immunoreactivity normally observed in the arcuate nuclei was no longer detectable in hypophysectomized rats, and the intense GAL immunoreactivity of the external zone of the median eminence progressively decreased and completely disappeared 3 and 6 weeks after hypophysectomy. In contrast, in the neurohypophyseal system, there was an increase of GAL labelling of the perikarya and emerging axons in the supraoptic and lateral-paraventricular nuclei, 1 and 3 weeks after hypophysectomy, that disappeared 6 weeks after hypophysectomy. An increase of GAL immunoreactivity was also observed in the internal zone of the median eminence 1 week but not 3 weeks after hypophysectomy. We conclude that hypophysectomy reduces the content of GAL and GAL mRNA in the rat hypothalamus. These changes are time-dependent and clearly detected after 3 weeks. The neurohypophyseal and hypophysiotropic galaninergic systems respond differently to hypophysectomy.(ABSTRACT TRUNCATED AT 250 WORDS)

Reported rates, incentives, and effectiveness of major vaccinations in 501 attendees at two diabetes clinics

body assay (Cobas Fara II, Roche) was 7.2%. This confirms the true interference between hydroxyurea and the HPLC measurement of HbAlc. Others factors may have affected the HbAlc value in our patient such as liver cirrhosis (but without important hepatic failure), splenectomy, and polycythemia vera, which could influence the rate of the glycation of hemoglobin by modifying erythrocyte life span. These factors should, however, not result in discrepant results between HPLC and immunoassay. The acetylation of hemoglobin is unlikely to have played a role since the patient was only taking 100 mg aspirin and was not actively drinking. In conclusion, several factors can affect glycated hemoglobin measurements by HPLC method. A thorough understanding of these factors is essential in interpreting the values of glycated hemoglobin. Clinicians should be aware that treatment with hydroxyurea may lead to falsely high HbAlc values measured by HPLC.

Plasma endothelin-1 immunoreactivity is increased following long-term dietary supplementation with omega-3 fatty acids in microalbuminuric IDDM patients.

Dear Sir, Circulatory concentrations of plasma endothelin-1 (ET-1), an endogenous vasoactive peptide, are increased in diabetes mellitus. Raised ET-1 levels have been proposed as a marker of endothelial dysfunction in this disease [1, 2]. We hypothesize that ET-1 changes could be associated with the endothelial/rheological effects of supplements of c0-3 fatty acids (o-3 FAs), a dietary intervention advocated in diabetes [3]. We measured plasma ET-1 immunoreactivity in 18 microalbuminuric IDDM patients (urinary albumin excretion rate 30-300 mg/24 h in at least two of three consecutive urinary collections), who were treated for 9 months, according to a double-blind schedule, with either 2.4 g/day co -3 FAs (84 % eicosapentaenoic, 16 % docosahexaenoic acids; gift of Sanofi, Brussels, Belgium; n = 8) or an inert placebo (n = 10). Patients in the two groups were comparable for age, sex, duration and complications of diabetes, insulin requirements, HbAlc , body mass index and waist-hip ratio. We also measured plasma ET1 in a group of normoalbuminuric IDDM patients (n = 23) as control. Plasma was obtained from venous blood taken into 9 mmol/1 benzamidine and 3 mmol/1 EDTA, and stored at -80~ ET-1 immunoreactivity was measured as previously described [4], after extraction on Cls-Se p Pack (Millipore, Milford, Mass., USA), using commercial antibody and standard (Peninsula Labs, Belmont, Calif., USA). As previously reported [5], ET-1 immunoreactivity was higher in microalbuminuric than in normoalbuminuric patients (1.9 + 0.2 vs 1.5 + 0.2 pmol/1, mean • SEM, n = 10 and 23, p < 0.05, Mann-Whitneys test). ET-1 immunoreactivity was further increased in co -3 FAs-supplemented microalbuminuric diabetic patients compared with those receiving placebo (2.4 + 0.1 vs 1.9 _+ 0.2 pmol/1, mean +_ SEM, n = 8 and 10, p < 0.05). ET-1 immunoreactivity was further characterized in one non-microalbuminuric, two placebo-treated microalbuminuric, and three co -3 FAs-supplemented microalbuminuric diabetic patients by reverse phase HPLC (24-44% acetonitrile gradient on a CIsTSKODS-120 T column, Toso Haas, Germany) (Fig. 1). ET1 immunoreactivity elute d similarly to synthetic ET-1 (Peninsula), appearing as two peaks, corresponding to oxidized-ET-1 and to the intact peptide (ET-1). Weak immunoreactivity was also detected close to the elution position of synthetic big ET-1. In contrast to ET-1, the immunoreactivity of plasma angiotensin II, another vasoconstrictor peptide, was similar in co-3 FAsand piacebo-supplemented patients (12.6 + 1.8 vs 14.6 + 1.9 pmol/1, n = 8 and 10). In conclusion, ET-1 plasma immunoreactivity is increased following long-term dietary supplementation with co-3 FAs to

Pituitary-Dependent Hormonal Regulation of Galaninergic Neurons in the Rat Hypothalamus

To investigate whether pituitary-dependent hormones may regulate galanin (GAL) content, synthesis and distribution in the hypothalamus, female hypophysectomized Wistar rats were treated for 2 weeks with subcutaneous injections of thyroxine (T4, 2 x 1 microgram), bovine growth hormone (GH, 2 x 125 micrograms), cortisol (C, 50 micrograms), subcutaneous implants of beta-estradiol (E2, 5-mm implant, dilution 1:1), or with the combinations [T4+GH], [T4+GH+C+E2] or [T4+GH+C+E2 + rat PRL, 2 x 125 micrograms] (doses/100 g BW/day). Concentrations of GAL in the hypothalamus were measured by radioimmunoassay (RIA) and GAL mRNA abundance was quantified by Northern blot (6 rats/group); 2 rats/group were used for immunohistochemistry. Hypophysectomy caused decreases of hypothalamic GAL peptide and mRNA concentrations (by 70 and 50%, respectively; p < 0.05 vs. intact rats). GAL immunoreactivity disappeared in the median eminence (ME), but increased in the neurohypophyseal magnocellular neurons of hypophysectomized rats. Substitution with T4, GH, [T4+GH], C or E2 had no significant effect on total hypothalamic GAL peptide and GAL mRNA concentrations. A treatment combining [T4+GH+C+E2] increased hypothalamic GAL (1.9 +/- 0.1 vs. 1.2 +/- 0.1 ng/mg protein in untreated hypophysectomized rats; p < 0.01) and GAL mRNA concentrations (127 +/- 19 vs. 59 +/- 2 densitometric units in untreated rats, p < 0.001). Addition of PRL to this combined treatment had no further effect. Treatment with T4, GH, [T4+GH] or E2 enhanced GAL labeling in the ME of hypophysectomized rats. The effect of estrogens was restricted to the GnRH-rich lateral regions of the ME. The combined treatment with [T4+GH+C+E2] restored the ME GAL immunoreactivity to levels observed in intact rats. In contrast, the increased GAL labeling observed in magnocellular neurons after hypophysectomy was not influenced by any hormonal treatment. In conclusion, hypophysectomy leads to marked reductions of hypothalamic GAL and GAL mRNA concentrations, and of GAL immunoreactivity in the ME. These reductions are prevented in part by a combined hormonal treatment associating T4, GH, C and E2, but not by any hormone given alone. This suggests specific pituitary hormone-dependent regulation of the hypophysiotropic GAL neurons. In contrast, the increased GAL labeling in magnocellular neurons of hypophysectomized rats persists despite hormonal treatment and likely represents a lesional effect on the neurohypophyseal GAL system.

Detection of low-range diabetic microalbuminuria: Micral-Test revisited.

We have found similar problems to those described by Rumley et al.’ in setting glycated haemoglobin metabolic control limits at the time of methodology change. We currently measure glycated haemoglobin by the Corning Glytrac method (Ciba Corning Diagnostics, Halstead, England) but have recently investigated an HbAl, method developed by Boehringer (Boehringer Mannheim UK Diagnostics and Biochemicals Ltd, Lewes, England). The mean & standard deviation (SD) for the HbAl Corning method in a local non-diabetic population was 7.0 % rt 0.8 resulting in good (less than mean + 2SD) and acceptable (mean + 2SD to mean + 4SD) control limits of 8.6 and 10.1 %, respectively. These values were also felt to agree with clinical assessment of metabolic control crudely assessed by presence or absence of specific diabetic complications. With the Boehringer HbAl, method in a similarly aged local nondiabetic group, the mean was 5.0 % 2 0.35 which would set good and acceptable control upper limits at 5.7 and 6.4 %, respectively. When metabolic control was subsequently assessed in a group of mainly Type 2 diabetic patients (n = 48) the results shown in Table 1 were obtained. It can be seen that if the Boehringer method for HbAl, is used in our routine clinical practice along with the consensus guidelines, then many of those patients previously classified as having acceptable or good control will be defined as having poor glycaemic control. If the results obtained on the same sample by both methods are plotted against each other, then regression analysis can be used to obtain the HbAl, levels corresponding to good or acceptable control as defined by HbAl measurement. A similar approach was used by Rumley et a/.’ This will, as expected, improve the agreement between classification of control by the two methods. The recently published consensus guidelines for Type 1 diabetic patients3 employ the now generally accepted philosophy of defining control categories by mean plus multiples of the SD but also provide specific values for both HbAl, and HbA,. For Type 1 diabetic patients when using the mean and multiples of the SD, good and borderline glycaemic control have been defined as less than + 3 SD and 3 SD to 5 SD, respectively. These differences in the guidelines for Types 1 and 2 diabetic patients, with respect to glycaemic control, highlight their arbitrary nature and may create practical problems. The validity of the specific cut-off points chosen may indeed be called into question by the Diabetes Control and Complications Trial4 wherein the intensive therapy group of Type 1 patients appear to have HbAl, results in the ‘borderline’ range 3-5 SD above the mean. These recent results suggest that published guidelines may well contain unrealistic targets. If, in addition, assay refinement leads to reallocation of control category as Rumley et a/.‘ and ourselves have shown, the use of the published guideline limits to audit clinic performance by purchasers of healthcare, will be fraught with problems. Glycated haemoglobin centile charts have been proposed for paediatric use.5 While that approach may not be particularly relevant to adult practice some alternative to using multiples of SD and/or a major rethink of suggested control limits seems desirable.