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J Cabezas-Cerrato

Publications and source records attributed to J Cabezas-Cerrato.

At least 55 records · Page 3Linked to original sources
PubMed1989

Quantification of glycation-induced browning in lens crystallins. A simple method for studying the advanced products of the Maillard reaction.

Differential scanning spectroscopy revealed a clear relationship between the degree of in vitro glycation of pig lens crystallins and its optical density at the range of 350-400 nm. This relationship is also shown in bovine serum albumin, used as a standard. In order to study the glycation browning in a large-scale number of samples, various spectroscopic indices have been tested, and the most discriminating became to include the absorbance at 375 nm with a correction of the background absorption at 300 and 500 nm (A3-W index). This index is proposed as a simple method for quantifying advanced products of the Maillard reaction in crystallins and other biological samples.

Animals↗
PubMed1989

[Cardiovascular parasympathetic and orthosympathetic lesions in alcoholism and their association with peripheral polyneuropathy].

Our aim was to identify the damaged baroreceptor reflex in alcoholic patients, and its association to peripheric neuropathy, and the electrophysiological data of primary axon damage and secondary myelinic damage. We measured the R-R interval and the blood pressure resting, after valsalva maneuver, six deep breathing/min and decubitus-biped, changing position, in 22 alcoholic patients and 22 healthy persons. Electromyography was performed, measuring the nerve conduction velocity and peripheral latency time of sciatic-popliteal external and internal nerves. We observed important damage of the cardiac parasympathetic and vascular sympathetic system, probably extended to the sympathetic cardiac system because the median cardiac rate of the alcoholic and the healthy person were similar. These lesions were associated with each other and with the motor neuropathy, with simultaneous development and common pathogenic mechanism. Finally, the R-R response had minimal amplitude during deep breathing without velocity alteration, suggesting an axonal alteration more evident than myelinic damage.

Adult↗
PubMed1988

Low glycation level and browning in human cataracts.

The extent of human cataract glycation has been determined by the 5-HMF/TBA method in 236 samples (53 from diabetic patients and 183 from non-diabetic controls). The brownish-yellow coloration typical of the advanced products of the Maillard reaction was measured spectrophotometrically. Glycation of crystallins was three times higher in diabetics than in controls, and was positively correlated with age in the latter group. The two groups did not differ significantly as regards the degree of browning, which was also uncorrelated with the primary products measured by the 5-HMF/TBA method. It is concluded that lens glycation is relatively mild and does not determine the intensity of the characteristic brownish-yellow colour of diabetic and senile cataracts. It is suggested that other coloured compounds produced with age interfere at the relevant wavelengths.

Age Factors↗
PubMed1988

Accumulation of glycation products in alpha-H pig lens crystallin and its bearing to diabetic cataract genesis.

The incorporation of 14C-glucose in native pig crystallin by in vitro incubation was found, after subsequent dialysis, to affect all 5 classes of crystallin separated by Sepharose CL-6B column chromatography. Though the radioactivity of the alpha-H fraction was three times greater than that of any of the others, autoradiographs of SDS-PAGE gels showed 14C-glucose adducts to be present in all soluble protein subunits, without there being any evidence of preferential glycation of the alpha-H subunits. The concentration of stable glycation products in the alpha-H chromatographic fraction of soluble crystallins is suggested to be due the addition of glycated material to this fraction as result of glycation-induced hyperaggregation, and not because the alpha-H subunits were especially susceptible to glycation.

Animals↗
PubMed1988

The stable products of the non-enzymatic glycation of pig crystallins: new findings related to the pathogenesis of diabetic cataracts.

The incorporation of 14C-glucose in native pig lens crystallins by in vitro incubation was found, after subsequent dialysis, to affect all five classes of crystallin separated by Sepharose CL-6B chromatography, but four times more radioactivity appeared in the alpha-H fraction than in any of the others (14.25 vs 3.16, 3.25, 1.69 and 2.30 kCPM/mg for alpha-H, alpha-L, beta-H, beta-L and gamma crystallins respectively). The autoradiographs of one- and two-dimensional electrophoresis patterns nevertheless showed the total radioactivity to be quite evenly distributed among the various subunits of the proteins; the alpha-H subunits did not exhibit a markedly greater affinity for glucose than the others. The high levels of stable glycation products in the alpha-H fraction are therefore attributed to the fraction's increasing during glycation rather than to its components being especially susceptible to glycation. This finding is interpreted as supporting the glycation-originated protein hyper-aggregation theory of the pathogenesis of diabetic cataract.

Animals↗
PubMed1987

Beta cell response to the hyperglycaemic clamp in three patients with insulinoma: a study using a hyperglycaemic glucose clamp.

To determine the mechanism responsible for deficient carbohydrate metabolism in patients with insulinoma, we studied three affected patients and seven normal controls using the hyperglycaemic clamp method (8.4 mmol/l) with the BIOSTATOR (GCIIS). In insulinoma patients, the amount of glucose necessary to reach the hyperglycaemic clamp was less than that required in normal controls (6.19 +/- 1.19 mg/min/kg vs. 9.95 +/- 0.53 mg/min/kg) (p less than 0.05). There was no significant difference in metabolized glucose (M) in the stable phase of the hyperglycaemic clamp; however, the M/IRI in this phase was less in those with insulinoma (7.9 +/- 0.50) than in controls (22.26 +/- 4.14) (p less than 0.05). There was no difference in beta cell secretory response to hyperglycaemic stimulus (defined as the increase in the concentration of C-peptide from the basal state to the stable phase of the hyperglycaemic clamp) between the two groups. Hepatic insulin extraction was significantly lower in patients with insulinoma than in normal controls (+0.72 +/- 0.07 vs. +0.85 +/- 0.01). Finally, the ratios of fractional turnover of glucose (K/IRI); glucose clearance/IRI and total rate of elimination of glucose from the extracellular pool/IRI were also all lower in patients with insulinoma than in controls (p less than 0.05). These data support the conclusion that deficient glucose metabolism seen in these patients is not related to a lack of response to glucose on the part of normal or neoplastic islet tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma, Islet Cell↗
PubMed1987

Adrenal cortex and type II polycystic ovary syndrome.

The aim of this study was to investigate whether the adrenal gland participates in the pathogenesis of type II polycystic ovary syndrome (PCO), and, if so, to see if an altered pattern of ACTH secretion might be responsible. Circadian secretion and pulsatility (morning and evening) of ACTH, and adrenal and pituitary responsiveness to exogenous ACTH and GnRH, respectively, were evaluated in 10 women with type II PCO and 10 normally menstruating women. After the patients had been administered oral dexamethasone (0.5 mg each night) for 3 months, studies were repeated. Mean plasma values of PRL, testosterone, DHA-S and 17-OH progesterone (17-P) measured by RIA were significantly higher (p less than 0.05) in patients than in controls. FSH and sex hormone binding globulin (SHBG) were significantly lower (p less than 0.05). Cortisol and 17-P responses to ACTH, and the LH/FSH ratio (both in basal conditions and after GnRH stimulation) were significantly higher (p less than 0.05) in patients. ACTH circadian secretion and pulsatility were similar in both groups. Treatment with dexamethasone significantly reduced plasma values of testosterone, DHA-S, androstenedione (adione), cortisol and the LH/FSH ratio (basal and after GnRH), but adrenal hyperresponsiveness to ACTH was maintained. ACTH pulsatility and secretion were significantly (p less than 0.05) reduced in the morning. Our results suggest that there are abnormalities at the adrenal level in type II PCO. Given that ACTH secretion appears to be normal and that adrenal hyperresponsiveness is still observed after treatment with dexamethasone, it is tempting to speculate that excessive trophic stimulation of the gland by a factor other than ACTH could exist in such patients.

17-alpha-Hydroxyprogesterone↗
PubMed1986

Acromegaly and insulin resistance: a case study.

Elevated levels of growth hormone (GH) alter both the glucose tolerance and the sensitivity of peripheral tissue to insulin. We have studied the relationship between impaired glucose metabolism and its variations with different plasma levels of endogenous GH in one patient with acromegaly. To do so, we studied the decline in blood glucose concentration, as induced by iv insulin infusion, from a given hyperglycaemic level. With high levels of GH (GH = 120 micrograms/l), the slope of the straight line representing the decrease in blood glucose after insulin infusion was -0.71, the time required to achieve normoglycaemic levels, 270 min, and the corrected area under the curve representing blood glucose 26 070 units2. After 10 months' bromocriptine treatment, GH plasma concentration fell to 8 micrograms/l, at which point the slope of the straight line was -1.40, the time required to achieve normoglycaemic levels 115 min, and the area under the curve 8956 units2. There was a greater total clearance of glucose when GH levels were lower (1.90 vs 1.00 ml/min/kg), as well as greater elimination of glucose from the extracellular glucose pool (4.02 vs 1.67 mg/min/kg). In conclusion, in this patient the elevated plasma levels of endogenous GH induced insulin resistance. Once GH levels were reduced by the administration of bromocriptine, glucose metabolism improved.

Acromegaly↗
PubMed1985

Metabolic and hormonal parameters after insulin-induced hypoglycemia in man, comparison between biosynthetic human insulin and purified pork insulin.

Although clinically undistinguishable, some authors have found important differences in the counterregulatory response between Biosynthetic Human Insulin (BHI) and Purified Pork Insulin (PPI). To reassess the problem 10 healthy volunteers of both sexes underwent paired iv insulin tolerance test with both BHI and PPI (0.10 U/kg b.w.). To check the humoral response the variations of glucose, free fatty acids (FFA), prolactin, growth hormone, ACTH and plasma renin activity were evaluated. Blood glucose depression and further recovery by BHI and PPI administration paralleled each other, so were, prolactin, FFA, and plasma renin activity. A slight section of ACTH, and GH was observed under BHI challenge. There were not statistically significant differences between both insulins on any of the six parameters studied. The data do not confirm earlier published reports indicating hormonal and metabolic differences between human and porcine insulin.

Adrenocorticotropic Hormone↗