Properly timed injections of cortisol and prolactin produce long-term reductions in obesity, hyperinsulinaemia and insulin resistance in the Syrian hamster (Mesocricetus auratus)

Naturally obese female Syrian hamsters were injected daily with prolactin at 0 or 12 h after cortisol injections for 10 days while held in constant light. Controls were similarly injected with saline. Animals were then held on short daylengths (10 h light:14 h darkness) for 10 weeks. They were allowed free access to food and water from birth to time of death. Ten weeks after treatment, retroperitoneal fat stores, plasma concentrations of insulin and glucose, and hypoglycaemic responsiveness to exogenous insulin were determined. The control groups as well as the 12-h hormone treatment group were obese, hyperinsulinaemic and insulin resistant. However, the 0-h treatment dramatically reduced retroperitoneal fat stores (41-55%), plasma insulin concentration (60-70%) and the insulin to glucose ratio (63-68%) compared with controls. Values for these parameters in the 0-h treatment groups were similar to those of their lean litter-mates. Furthermore, the 0-h group but not the 12-h group was more sensitive than control animals to the hypoglycaemic effects of exogenous insulin at doses 0.2 and 2.0 U/kg body weight. These results demonstrate that timed daily injections of cortisol and prolactin in specific temporal relationships can produce marked reductions in obesity, hyperinsulinaemia and insulin resistance in the Syrian hamster that persist long after the termination of treatment. This study also suggests an important role for the interactions of circadian neuroendocrine systems in the regulation of these metabolic states.     

High molecular weight kininogen: localization in the unstimulated and activated platelet and activation by a platelet calpain(s)

High mol wt kininogen (HMWK), the major cofactor-substrate of the contact phase of coagulation, is contained within and secreted by platelets. Studies have been performed to localize platelet HMWK in both the unstimulated and activated platelet and to ascertain the effect of platelet enzymes on HMWK itself. On platelet subcellular fractionation, platelet HMWK was localized to alpha-granules, and platelets from a patient with a deficiency of these granules (gray platelet syndrome) had 28% normal platelet HMWK. Platelet HMWK, in addition to being secreted from the platelet, was also localized to the surface of the platelet when activated. Using a competitive enzyme- linked immunosorbent assay for HMWK as an indirect antibody consumption assay, the external membrane of thrombin-activated platelets as well as the releasate from these stimulated platelets had 17 ng HMWK antigen/10(8) platelets available, whereas unstimulated platelets and their supernatant had only 4.9 and 4.2 ng HMWK/10(8) platelets present, respectively. The anti-HMWK antibody consumption by activated normal platelets was specific for membrane-expressed platelet HMWK, since activated platelets from a patient with total kininogen deficiency did not adsorb the anti-HMWK antibody. Enzymes in the cytosolic fraction of platelets cleaved 125I-HMWK (mol wt 120,000) into a mol wt 100,000 polypeptide as well as smaller products at mol wt 74,000, mol wt 62,000, mol wt 47,000, and a few components below mol wt 45,000. No cleavage products were observed when DFP and leupeptin were present. The cleavage of HMWK was specifically prevented by inhibitors of calcium-activated cysteine proteases (leupeptin, N-ethylmaleimide, iodoacetamide, and EDTA) but not by inhibitors of serine proteases (DFP, benzamidine, soybean trypsin inhibitor, or aprotinin). Platelet cytosol increased the coagulant activity of exogenous purified HMWK with maximum HMWK coagulant activity (35-fold) occurring within ten minutes of exposure to platelet cytosol. Treatment of platelet cytosol with leupeptin prevented the increase in the coagulant activity of exogenous HMWK. These studies indicate that activated platelets express platelet HMWK on their external membrane and platelet enzymes can cleave and increase the coagulant activity of exogenous HMWK.     

Intramitochondrial dyes allow selective in vitro photolysis of carcinoma cells.

Carcinoma cell mitochondria preferentially accumulate and retain certain cationic dyes to a much greater extent than most normal cells. Thus, they can potentially serve as targets for highly selective photochemotherapy. We evaluated 10 rhodamine and cyanine dyes as carcinoma-specific mitochondrial photosensitizers in vitro. The most effective, N,N'-bis(2-ethyl-1,3-dioxolane)kryptocyanine (EDKC), caused marked, light-dependent killing of human bladder, squamous, and colon carcinoma cell lines after 30-min incubations at 1-0.01 microM but was minimally toxic to human keratinocytes and to normal monkey kidney epithelial cells (CV-1). Carcinoma cell phototoxicity was proportional to the amount of dye incorporated by the different cell lines. Selective killing ratios were 70-1000 for 0.1 microM dye and light doses of 100-175 J/cm2 between 680 and 720 nm.     

Abnormal renal vasodilation to an amino acid infusion in congestive heart failure: normalization by enalapril

In congestive heart failure (CHF), the neurohormonal mechanisms that cause renal vasoconstriction, particularly those depending on the renin-angiotensin system, could interfere with renal vasodilating mechanisms. To elucidate this issue, we studied the kidney response to an amino acid infusion (known to cause renal vasodilation in healthy individuals) in eight patients with CHF. We found that the amino acid infusion (0.7 mL/kg/h of a 10% solution) elicited no renal hemodynamic response, in marked contrast to healthy subjects. We next hypothesized that the renin-angiotensin system (known to be activated in heart failure) has a role in the lack of response to the amino acid infusion. To test this hypothesis, we repeated the study after two 5-mg doses of enalapril, an inhibitor of the angiotensin-converting enzyme, administered 12 hours apart. After enalapril treatment, the amino acid infusion caused a 45% increase in mean renal blood flow (RBF) from 383 +/- 55 to 557 +/- 51 mL/min at the fifth hour (P < 0.05). This normalization of the renal response to the amino acid infusion occurred without changes in cardiac output or in systemic vascular resistance. Hence, the renal fraction of the cardiac output increased during the amino acid infusion. The recovery of the renal vascular response was not accompanied by an increase in glomerular filtration rate (GFR; filtration fraction decreased), suggesting a predominant efferent arteriole dilatation. Our study shows that, in heart failure, the kidney loses its ability to increase RBF in response to an amino acid load. This lack of renal vascular response can be restored by inhibiting the renin-angiotensin system and is unrelated to changes in systemic hemodynamics.     

Motor imagery in a locked-in patient: evidence from transcranial magnetic stimulation

Motor evoked potentials (MEPs) to transcranial magnetic stimulation were evaluated in a case of locked-in syndrome due to a large pontine infarction. In this patient, magnetic resonance imaging (MRI) and somatosensory evoked potentials demonstrated a tegmental involvement. One month after the attack, no MEP could be recorded from the right abductor digiti minimi (ADM) or either tibialis anterior muscle. On the contrary, MEPs were obtained from the left ADM, although with a prolonged latency and a reduced amplitude. When the patient was requested to think about the abduction of her paralyzed left little finger, the latency and the elicitability of these responses improved as compared with the relaxed condition. These severe MEP alterations correctly predicted a poor recovery of motor function in the chronic stage. However, although the tegmental involvement raises the question of an insufficient cortical motor arousal, preserved motor imagery suggested a normal cortical motor area activation.     

Cardiac function in fetuses of poorly-controlled pre-gestational diabetic pregnancies--a pilot study

OBJECTIVE: Cardiac impairment is frequently found in babies of diabetic mothers. It is still controversial whether this is due to poor glucose control. The aim of this study is to compare the cardiac function in fetuses of well- and poorly-controlled pre-gestational diabetic pregnancy in third trimester. METHODS: Women with type 1 pre-gestational diabetes were enrolled at 30-32 weeks. Cardiac size and interventricular septal wall thickness were measured by M-mode at end-diastolic phase. The right and left ventricular ejection fractions were calculated. At the mitral and tricuspid valves inflow, the ratio between early ventricular filling and active atrial filling (E/A) at both atrioventricular valves were measured by Doppler echocardiography. Peak velocities of ascending aorta and pulmonary artery were assessed. The angle of isonation was kept at <20 degrees. Women with poorly-controlled diabetes (HbA1c>6.5%) were compared with those with satisfactorily controlled diabetes (HbA1c < or = 6.5%). RESULTS: A total of 21 women with pre-gestational diabetes were recruited for this study. Eight women with well-controlled diabetes were compared with 9 women who had poorly-controlled diabetes. HbA1c in the poorly-controlled group was 7.3% and in the well-controlled group it was 5.4% (p<0.001). There was no difference between the two groups in cardiac size, interventricular septal wall thickness, ejection fraction, aorta and pulmonary artery peak flow velocities. The right atrioventricular E/A ratio was significantly lower among the poorly-controlled diabetic pregnancies (0.71 vs. 0.54; p<0.05). CONCLUSION: Fetuses of poorly-controlled diabetic mothers had a lower right atrioventricular E/A ratio. This may be due to metabolic acidosis, non-hypertrophic cardiac dysfunction or fetal polycythemia.