Altered IGF-I and IGFBPs in senescent male and female rats.

The effects of senescence on muscle characteristics and the insulin-like growth factor I (IGF-I) pathway were assessed in male and female BN/F344 rats. The mass and total ATPase activity of gastrocnemius and plantaris muscles were reduced with age and to a greater extent in males than in females. The mass and total ATPase activity of soleus muscle were not significantly altered with age. Circulating IGF-I was also significantly reduced with age, 60% in females and 21% in males. Circulating IGF-binding protein 3 (IGFBP-3) was reduced with age. In liver and gastrocnemius muscle, mRNAs for IGF-1, IGFBP-2, and IGFBP-3 were analyzed in young and aged males of two strains, BN/F344 and Sprague-Dawley. In BN/F344 rats, liver mRNAs were unchanged with age. Also in BN/F344 rats, muscle mRNAs for IGFBP-2, and IGFBP-3 displayed nonsignificant trends toward increase with age. In aged Sprague-Dawley males, liver mRNA for IGF-I was increased 15% and muscle mRNA for IGFBP-2 was increased 110%. Thus, different age-related changes in the growth hormone (GH)/IGF pathway occur in males and females between the sexes and strains. These changes may play a role in the muscle atrophy associated with senescence.

Decreased immunosuppressive effect of cortisol on natural killer cytotoxic activity in senile dementia of the Alzheimer type.

Former studies have indicated alterations of the cytotoxic activity of natural killer (NK) cells in senile dementia of the Alzheimer type (SDAT). These changes may be related to the increased reactivity of NK cells with cytokines, even if an impairment of the immunosuppressive effect of glucocorticoids cannot be excluded. In the present study we have demonstrated a lower immunosuppressive effect of cortisol on NK cytolytic function in patients with SDAT than in healthy elders and in patients with dementia of multi-infarct origin (MID). This suppression is completely lacking when cortisol is employed at low concentrations (10(-7) M) and is significantly reduced after incubation at physiological (10(-6) M; p < 0.001) and supraphysiological concentrations (10(-5) M; p < 0.001). The addition of IL-2 (50 and 100 IU/ml/cells) significantly antagonizes the effects of cortisol in SDAT, whereas the cortisol-dependent immunosuppression is partially maintained in healthy elders and in patients with MID. Our data indicate that the defect of the immunosuppressive effect of cortisol may play a role in NK dysregulation in SDAT, contributing to the cytokine-mediated NK overactivity in this disease.

Nephelometry in the clinical assessment of glomerular proteinuria and tubular function in diabetic nephropathy.

Urinary excretion rate and total clearances of albumin, IgG, IgA and alpha 1-microglobulin, together with selectivity index and proteinuria, were determined by computerized nephelometry in 187 IDDM and NIDDM diabetic out-patients and in 39 healthy subjects in order to perform a prompt clinical assessment of diabetic nephropathy. Significant correlations between nephelometric and RIA procedures were demonstrated for the urinary excretion of albumin (p < 0.001) and total IgG (p < 0.001) in diabetic patients and healthy subjects. Nephelometry allowed us to classify diabetic patients in different stages of nephropathy: non nephropathic, normoalbuminuric with hyperfiltration, with incipient (microalbuminuric) and overt nephropathy (macroalbuminuric). Thirty consecutive subjects were analyzed within 1 h from the beginning of the procedure. A normal tubular function was demonstrated in non nephropathic, hyperfiltering and in 34% of microalbuminuric diabetic patients. On the contrary, in 66% of microalbuminuric and in 93% of macroalbuminuric patients alpha 1-microglobulin urinary levels were found above the upper normal limit. Urinary excretion of IgA was significantly increased only in macroalbuminuric diabetic patients (p < 0.001); this marker might therefore characterise the stage of overt nephropathy. Computerized nephelometry can be considered as a prompt, reproducible and high sensitive approach in the clinical evaluation of proteinuria and tubular function in diabetic renal disease.

Excitatory pattern of gamma-interferon on natural killer cell activity in senile dementia of the Alzheimer type.

Spontaneous natural killer (NK) cell activity and NK-induced cytotoxicity after interferon-gamma (IFN-gamma) were measured in healthy elderly subjects and in patients with senile dementia of Alzheimer type (SDAT) and multi-infarct dementia (MID). Normal basal and IFN-gamma-stimulated NK cytotoxicity were found in healthy old subjects and in patients with MID. On the contrary higher NK cytotoxicity after IFN-gamma (650 IU) was demonstrated in SDAT patients than in MID and healthy subjects (p < 0.001). A significant inverse correlation between the percent increase of NK cytotoxicity after IFN-gamma and the Mini Mental State Examination score (p < 0.001) was also demonstrated in patients with SDAT. Our data might suggest a cytokine-dependent mechanism of NK activation in SDAT associated with the neuroimmune hypothesis of the disease.

Retrospective analysis of long-term hemorheologic effects of pentoxifylline in diabetic patients with angiopathic complications.

Blood rheology alterations have often been reported in diabetic patients and may be associated with an increased risk for diabetic vascular disease. In this light a hemorheologic approach with pentoxifylline has been suggested in diabetic patients with hemorheological changes in order to improve the hemorheology approach and to evaluate the long-term effects of this treatment on the other clinical and metabolic variables. The study concerned a 10-year retrospective analysis of diabetic patients with hemorheologic alterations and angiopathic complications. Pentoxifylline (Trental 400) significantly reduced blood and plasma viscosity (at high and low shear-rates), fibrinogen and erythrocyte aggregation, and increased erythrocyte filterability throughout the study. The improvement of the hemorheologic pattern was obtained independently of the variation in glycometabolic control and body weight changes, whereas concomitant reductions of arterial blood pressure levels and of urinary excretion of albumin and total proteins was observed during the treatment. Pentoxifylline might therefore be successfully employed for long-term periods in the treatment of hemorheologic disorders in diabetic patients without effects on the metabolic pattern.

Hyperviscosity and microproteinuria in central obesity: relevance to cardiovascular risk.

OBJECTIVES: To investigate the role of blood rheology changes in the occurrence of glomerular proteinuria in obese patients with central fat distribution. SUBJECTS: Fifty-nine obese out-patients (31 with central and 28 with peripheral body fat distribution) and 24 healthy subjects. MEASUREMENTS: Blood and plasma viscosity (Rotational viscometer CV100 HAAKE), erythrocyte deformability (whole-blood filtration time), fibrinogen (nephelometry), urinary excretion rates of albumin, IgG, transferrin and IgA (nephelometry). RESULTS: Higher blood viscosity (at low and high shear-rates), plasma viscosity, fibrinogen, erythrocyte aggregability and lower erythrocyte deformability were found in patients with central obesity than in patients with peripheral obesity (P < 0.01) and in healthy subjects (P < 0.001). Furthermore an increased urinary excretion rate of albumin (P < 0.001), IgG (P < 0.001), transferrin (P < 0.01) and IgA (P < 0.05) was found in patients with central obesity than in the other two groups. Blood hyperviscosity (at shear-rate 1 s-1 and 1/200 ratio) significantly correlated with the amount of urinary excretion of proteins independently of the other clinical and metabolic variables. CONCLUSIONS: The data demonstrated haemorheologic disorders related to pathologic proteinuria in patients with central obesity. The interaction between these two components may increase the risk of widespread cardiovascular disease.

Regulation of cyclic GMP levels in the rat frontal cortex in vivo: effects of exogenous carbon monoxide and phosphodiesterase inhibition.

A microdialysis method combined with a sensitive radioimmunoassay was used to monitor cGMP release in the frontal cortex of the anesthetized rats in vivo. We assessed the relative contribution of endogenous nitric oxide (NO), and effects of exogenous carbon monoxide (CO) and phosphodiesterase activity, as possible regulators of cortical CGMP levels. Perfusion with CO-saturated aCSF (approximately 1 mM CO) failed to significantly stimulate cortical cGMP levels. For comparison, cerebellar cGMP levels increased by 2-fold during CO stimulation, followed by a prolonged response that was fully reversible with the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). Cortical perfusion with zinc protopophyrin-IX (100 microM), a widely used inhibitor of the CO-generating enzyme heme oxygenase, suppressed cGMP levels by 50%, a response that spontaneously recovered in spite of the continuous presence of the metalloporphyrin. Perfusion with isobutylmethyl xanthine IBMX (1 mM) resulted in 5-fold increase in cortical cGMP levels, as compared to basal levels without IBMX. In the presence of IBMX, L-NAME suppressed basal cortical cGMP levels by 70% indicating that NO synthase activity generates the bulk of cGMP in this brain region, as previously shown for basal cGMP production in the hippocampus and the cerebellum. These data also emphasize a crucial role for phosphodiesterase activity in the maintenance of cGMP levels in vivo in the frontal cortex. The relatively weak responses to exogenous CO lend little support for a role of this gas in regulating basal cortical cGMP levels in vivo.

Circadian neuroendocrine functions in disorders of eating behavior.

Eating behavior is a complex function determined by regulatory mechanisms characterized by bioperiodic fluctuations. It involves the hypothalamus as well as the related higher centers in the central nervous system (CNS). Many hormones, neurotransmitters and neuropeptides play an important role in the synchronization of food intake. Our study therefore sets out to evaluate the circadian rhythms of several endocrine functions in women with eating disorders, to clarify the pathophysiology of the limbic-hypothalamic system. We measured the circadian rhythms of plasma melatonin, serum cortisol, growth hormone (GH) and prolactin (PRL) in 26 patients with anorexia nervosa (AN), 27 with primary obesity (OB) and 7 with bulimia nervosa (BN). Simultaneous evaluation of different neuroendocrine rhythms in these three groups revealed similar circadian abnormalities, (namely daytime persistence of melatonin secretion in AN and OB, and similar cortisol profile changes in AN and BN), together with evidence of internal desynchronization among the different bioperiodic functions. These findings suggest that some changes of the central pathways involved in the control of eating, mood and endocrine functions are common to dissimilar kinds of eating disorders.

Enhanced cytotoxic response of natural killer cells to interleukin-2 in Alzheimer's disease.

Experimental data suggest an involvement of immune cellular components in the development of Alzheimer's disease (AD). Against this background, the spontaneous natural killer (NK) cell activity and the NK-induced cytotoxicity after interleukin-2 (IL-2) were studied in healthy elderly subjects and in patients with dementia of Alzheimer type (SDAT) and multi-infarct type (MID). Higher NK cytotoxicity (expressed as total lysis and percent increase) at different IL-2 concentrations (50 and 100 IU/ml/cells) was demonstrated in patients with SDAT than in healthy elderly subjects (p < 0.001) and MID patients (p < 0.001). NK cell activity of MID patients was similar to that of healthy elderly and healthy young subjects. A negative correlation between the percent increase in NK cytotoxicity after IL-2 and the Mini Mental State Examination Score was also found in SDAT patients (p < 0.01). Alterations of IL-2-mediated NK cytotoxicity may therefore support the neuroimmune hypothesis of AD.