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Biomedical subjects

P Marchetti

Publications and source records attributed to P Marchetti.

At least 217 records · Page 12Linked to original sources
PubMed1988

Insulin degradation into monocytes from normal subjects: a high performance liquid chromatographic analysis.

In this work the fate of A14-125 I-insulin inside human cells has been investigated by the complementary use of gel permeation and reversed-phase high performance liquid chromatography to obtain a better resolution of the cell processed radioactive material resulting from the internalization of labeled insulin. Mononuclear leukocytes from 12 normals were incubated with pure A14-125 I insulin at 37 C and internalized radioactivity was characterized after 2, 15 and 60 min. Nearly 14% of intracellular radioactivity was associated to materials with a molecular weight of approximately 300,000. The remaining 86% had a molecular weight lower than 20,000. High molecular weight material showed an elution profile very similar to that obtained from purified human placental insulin receptor and was partially precipitable with antireceptor antibody. The reversed phase high performance liquid chromatography analysis of the low molecular weight material showed two main peaks corresponding to 125 I and A14-125 I-insulin and three intermediate peaks, a, b, c, accounting for about 8% of the recovered radioactivity. By increasing the incubation time of A14-125 I-insulin with monocytes a decrease of insulin peak (2 min: 38 +/- 18%; 15 min: 25 +/- 11%; 60 min: 6 +/- 4%) and a corresponding increase of iodide peak was observed. Immunoprecipitability with anti-insulin antibody was 0% for iodide and a peaks, 60% for peak b, 78% for peak c and 90% for A14-insulin peak. Our results show that intracellular insulin degradation procedes rapidly and in a time-dependent manner and that this process produces insulin derivatives which partially retain the immunological properties of intact A14-125 I insulin.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[A case of factitious hypoglycemia with unusual presentation].

In this paper the Authors describe a case of factitious hypoglycemia in a 30-year-old nurse who came to the practitioner saying she was drug-addict. A careful history and the clinical examinations showed that the symptoms were due to hypoglycemic episodes. The finding of high plasma insulin levels together with low plasma C-peptide concentrations enabled us to exclude organic causes of hypoglycemia, suggesting the diagnosis of factitious hypoglycemia. After the patient was told we suspected a case of factitious hypoglycemia, the symptoms disappeared.

Adult↗
PubMed1988

Salivary immunoreactive insulin: a new entry in clinical chemistry?

The distribution of salivary immunoreactive insulin (S-IRI) and its relation to plasma insulin (P-IRI) and other clinical and metabolic variables were investigated in 93 nondiabetic subjects (60 males, 33 females, ages 11-70 y). S-IRI was measured by RIA, with monoiodinated insulin as labeled antigen and with standards consisting of serial dilutions in saliva of known amounts of native insulin. The sensitivity of the method was 12.1 pmol/L. The intra- and between-assay CVs were near 10%, and analytical recovery exceeded 93% for various insulin concentrations added to saliva. S-IRI, measured after overnight fast, showed a nonguassian distribution in males (skewness 1.18, kurtosis 1.41) and females (skewness 1.71, kurtosis 1.18); mean and median values were higher in males (14.3 and 12.1 nmol/min) than in females (12.1 and 7.15 nmol/min), but not significantly so. S-IRI was significantly correlated with P-IRI both in males (r = 0.75, P less than 0.0001) and females (r = 0.72, P less than 0.0001). These results, particularly the correlation between S-IRI and P-IRI, indicate the possibility of using S-IRI measurement in clinical practice.

Adolescent↗
PubMed1987

A simple integrator to process the electroencephalogram of small laboratory animals.

A simple integrator to process the EEG of small laboratory animals is described. This device simultaneously integrates, at fixed short intervals, average wave frequency (SF) and wave area (SA, in microV X sec), assumed as a simplified index of the actual EEG power. From these values the average wave area, SA/SF, i.e., the quantal component of SA is calculated. By measuring the average wave frequency and by calculating SA/SF, different conditions, such as arousal reaction, drug-induced EEG activation, seizures, and anesthesia can be easily distinguished and quantified. Moreover, this approach allows one to correlate the fundamental EEG parameters (wave frequency and SA/SF) with neurochemical signs of brain activity, such as the release of neurotransmitters from the brain. Thus, a more complete knowledge of the pharmacological profile of neuroactive compounds is made possible.

Acoustic Stimulation↗
PubMed1987

Plasma biguanide levels are correlated with metabolic effects in diabetic patients.

Metabolic abnormalities occur in biguanide-treated diabetic patients. We investigated the relationship between plasma metformin and phenformin concentrations and metabolic effects. Drug levels were measured in 37 type II diabetic patients by HPLC. The method was sensitive, specific, and linear over a wide range of drug concentrations. Metformin and phenformin values ranged from 236 to 718 ng/ml and from 28 to 114 ng/ml, respectively. The plasma metformin level was correlated with triglycerides (r = -0.55; P less than 0.05) but not with drug dosage, plasma glucose, HbA1, creatinine, creatinine clearance, lactate, pyruvate, lipid, and clinical parameters. Plasma phenformin concentrations correlated with lactate (r = 0.49; P less than 0.05) and HbA1 (r = 0.50; P less than 0.05) but not with drug dosage, parameters of diabetes control, creatinine, creatinine clearance, pyruvate, and clinical parameters. The clinical usefulness of this HPLC method, the evidence that the increase of lactate is related to the circulating phenformin levels, and the demonstration that the metformin effect on triglyceride metabolism is correlated to plasma drug levels are the positive findings of this work.

Aged↗
PubMed1987

Glucocorticoid receptors predict response to combination chemotherapy in patients with acute lymphoblastic leukemia.

Glucocorticoid receptor levels were quantified in leukemic blasts from peripheral blood of 86 patients with acute lymphoblastic leukemia. Subsequent achievement of complete remission correlated with high receptor levels. Forty-seven of 50 patients with leukemic cells containing more than 6,000 receptor sites and 22 of 36 patients with cells containing less than 6,000 receptor sites achieved remission. The study of glucocorticoid receptors in leukemic cells may predict response to combination chemotherapy in acute lymphoblastic leukemia patients.

Acute Disease↗
PubMed1987

Circulating lipid levels and severity of diabetic retinopathy in type I diabetes mellitus.

Plasma lipid levels have been proposed as probable risk factors of diabetic retinopathy. To clarify this question, we evaluated the apolipoprotein levels in 68 type I diabetic patients (39 +/- SD 14 years; duration of diabetes 13 +/- SD 8.4 years). By the analysis of fluorescein angiography we have classified diabetic retinopathy as follows: absent retinopathy (AR, n = 23), minimal retinopathy (MR, n = 16), exudative retinopathy (ER, n = 15), proliferative retinopathy (PR, n = 14). For all patients we measured: total, LDL- and HDL-cholesterol (T-CH, LDL-CH, HDL-CH), apolipoproteins A and B (Apo A and B), fasting plasma glucose (FPG), glycosylated hemoglobin (HbA1). The mean age of the patients with ER (47 +/- SD 14 years) was greater than those with MR (36 +/- SD 15 years) or AR (33 +/- SD 13 years) (p less than 0.05). Significant differences within groups were not found for relative body weight, daily insulin dose, FPG, HbA1% (analysis of variance, ANOVA). The groups differed between each other with regard to T-CH, LDL-CH and HDL-CH/LDL-CH ratio (T-cholesterol: AR 186 +/- SD 34, MR 191 +/- SD 32, ER 212 +/- SD 52, PR 215 +/- SD 41 mg/dl; LDL-cholesterol: AR 124 +/- SD 28, MR 122 +/- SD 18, ER 148 +/- SD 38, PR 145 +/- SD 33 mg/dl; HDL/LDL-cholesterol ratio: AR 0.38 +/- SD 0.1, MR 0.35 +/- SD 0.1, ER 0.30 +/- SD 0.1, PR 0.29 +/- SD 0.1). The total-CH levels increased and HDL-CH/LDL-CH ratio decreased along with the severity of the retinopathy.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Intracellular insulin processing is altered in monocytes from patients with type II diabetes mellitus.

We studied total cell-associated A14-[125I]insulin radioactivity (including surface-bound and internalized radioactivity), insulin internalization, and its intracellular degradation at 37 C in monocytes from nonobese type II untreated diabetic patients (n = 9) and normal subjects (n = 7). Total cell-associated radioactivity was decreased in diabetic patients [2.65 +/- 1.21% (+/- SD) vs. 4.47 +/- 1.04% of total radioactivity; P less than 0.01]. Insulin internalization was also reduced in diabetic patients (34.0 +/- 6.8% vs. 59.0 +/- 11.3% of cell-associated radioactivity; P less than 0.01). Using high performance liquid chromatography six intracellular forms of radioactivity derived from A14-[125I] insulin were identified; 10-20% of intracellular radioactivity had approximately 300,000 mol wt and was identified as radioactivity bound to the insulin receptor, and the remaining intracellular radioactivity included intact A14-[125I]insulin, [125I]iodide, or [125I]tyrosine, and three intermediate compounds. A progressive reduction of intact insulin and a corresponding increase in iodine were found when the incubation time was prolonged. Intracellular insulin degradation was reduced in monocytes from diabetic patients; intracellular intact insulin was 65.6 +/- 18.1% vs. 37.4 +/- 18.0% of intracellular radioactivity (P less than 0.01) after 2 min and 23.6 +/- 22.3% vs. 3.9 +/- 2.3% (P less than 0.01) after 60 min in diabetic patients vs. normal subjects, respectively. In conclusion, 1) human monocytes internalize and degrade insulin in the intracellular compartment in a stepwise time-dependent manner; and 2) in monocytes from type II diabetic patients total cell-associated radioactivity, insulin internalization, and insulin degradation are significantly reduced. These defects may be related to the cellular insulin resistance present in these patients.

Aged↗
PubMed1987

Long-term therapy with biosynthetic human insulin: importance of short-acting/intermediate-acting insulin ratio on determining efficacy of treatment.

This report describes the efficacy of biosynthetic human insulin (BHI) in long-term (one year) therapy of type I diabetic patients previously treated with conventional insulins. The results were compared with those obtained in a group of diabetic patients kept on their usual treatment. In the latter, fasting plasma glucose, HbA1, insulin dose and relative proportions of insulin formulations remained constant throughout the study. In patients switched to BHI, hypoglycaemic episodes occurred during the first week of treatment and fasting plasma glucose was higher than basally at the first two visits (7th and 30th days). Both hypoglycaemia and high fasting plasma glucose were avoided by reducing the amount of short-acting insulin and increasing that of intermediate-acting insulin, so that the short-acting/intermediate-acting insulin ratio was significantly lower during BHI therapy, although the total daily insulin dose remained unchanged. HbA1 levels remained fairly constant throughout the study. It was concluded that in order to achieve full clinical efficacy of BHI, it is important to modify the proportions of short- and intermediate-acting insulin preparations accurately when switching patients from conventional insulin to biosynthetic human insulin.

Adult↗
PubMed1986

A14-[125I]monoiodoinsulin purified by different high-performance liquid chromatographic procedures and by polyacrylamide gel electrophoresis: preparation, immunochemical properties and receptor binding affinity.

Reversed-phase high-performance liquid chromatography (RP-HPLC) allows the rapid separation of A14-[125I]monoiodoinsulin directly from the iodination mixtures. It remains to be clarified, however, whether the RP-HPLC chromatographic conditions affect the properties of the purified tracer. In this study we prepared A14-[125I]insulin purified by polyacrylamide gel electrophoresis (PAGE) and by three different RP-HPLC mobile phases containing, respectively, ammonium acetate, sodium perchlorate and trifluoroacetic acid. The binding characteristics of all these tracers were examined using an insulin antiserum and insulin cell receptors. The specific radioactivity corresponded to the theoretical maximum for the RP-HPLC-purified tracers and was significantly lower for the PAGE-purified tracers. Significant differences were found in the binding of different tracers to the insulin antiserum: maximum binding ranged from 94 to 99% and was significantly lower for tracers purified by RP-HPLC eluents B and C; antiserum dilution giving 50% tracer binding was lower for tracers purified by RP-HPLC eluent B. The four insulin derivatives showed no difference in non-specific precipitation and in the affinity constant values calculated from the Scatchard analysis. No significant difference was found in the binding of the four insulin derivatives to the human-cultured IM-9 lymphocytes and to the human circulating monocytes. In conclusion, the present work demonstrates that the immunological properties of the A14-[125I]monoiodoinsulin purified by RP-HPLC may be partially affected by the composition of the mobile phase. In order to obtain a fully potent A14-[125I]insulin derivative and to have the possibility of comparing data from different laboratories, the chromatographic conditions must be taken into account.

Adult↗
PubMed1986

Salivary insulin concentrations in type 2 (non-insulin-dependent) diabetic patients and obese non-diabetic subjects: relationship to changes in plasma insulin levels after an oral glucose load.

The presence of immunoreactive insulin in saliva and its relationship to plasma immunoreactive insulin was investigated in healthy subjects, newly diagnosed non-obese Type 2 (non-insulin-dependent) diabetic patients and obese non-diabetic subjects, basally and after an oral glucose tolerance test. The mean +/- SEM fasting values of plasma and salivary immunoreactive insulin were significantly higher in diabetic patients and obese non-diabetic subjects than in normal volunteers (p less than 0.05). During the glucose challenge, the increase of salivary insulin was related with that of plasma in the three groups of subjects, with a time lag in normal and obese subjects. In normal volunteers, plasma and salivary peak values were respectively 49.5 +/- 13.4 microU/ml (p less than 0.05 vs obese subjects) at 60 min and 12.0 +/- 3.3 microU/min (p less than 0.05 vs obese subjects) at 120 min; in diabetic patients, the values were 51.7 +/- 5.6 microU/ml (p less than 0.05 vs obese subjects) and 14.6 +/- 4.1 microU/min at 120 min; in obese subjects, the peak value for plasma insulin was 111.5 +/- 40.1 microU/ml at 90 min and for salivary insulin 15.6 +/- 5.1 microU/min at 120 min. A positive linear relationship was shown between plasma and salivary insulin during the oral glucose tolerance test. The identity of salivary insulin was assessed by reversed-phase HPLC. We conclude that salivary immunoreactive insulin can be found in Type 2 diabetic patients and in obese non-diabetic subjects, as well as normal volunteers, that plasma and salivary insulin are related after a glucose load, and that differences exist in salivary insulin secretion patterns among the three groups of subjects.

Adult↗
PubMed1986

Factitious hypoglycemia in an insulin-dependent woman in the eighth week of gestation.

An extremely rare case of factitious hypoglycemia in a young insulin-dependent pregnant woman in the first trimester of pregnancy is reported. Pregnancy resulted in the birth of a normal child. The clinical and laboratory procedures used to ascertain this diagnosis together with the psychological dynamics of the case are discussed.

Factitious Disorders↗