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Biomedical subjects

R Navalesi

Publications and source records attributed to R Navalesi.

At least 19 recordsLinked to original sources
PubMed1992

Coagulation and fibrinolytic system impairment in insulin dependent diabetes mellitus.

Selected coagulation and fibrinolytic parameters were assessed in 40 insulin dependent diabetes mellitus patients with varying degrees of metabolic control; 30 healthy subjects matched for age and sex formed the control group. Activated Partial Thromboplastin Time, Prothrombin Time, Fibrinogen, Factor VII, Antithrombin III, Protein C, Plasminogen, alpha 2-Plasmin Inhibitor, Plasminogen Activator Inhibitor-1, tissue-Plasminogen Activator were functionally evaluated. Antigenic levels of tissue-Plasminogen Activator, Thrombin-Antithrombin complexes and fibrinolytic specific product B beta 15-42 were also determined. Compared to the control group diabetic patients displayed significantly higher levels of Fibrinogen (p < 0.01), Factor VII (p < 0.01), Thrombin-Antithrombin complexes (p < 0.01) and Plasminogen Activator Inhibitor-1 activity (p < 0.01). Regardless of the normal level of the tissue-Plasminogen Activator-related antigen, diabetic patients had tissue-Plasminogen Activator activity lower than the control group (p < 0.05). Coagulation Factor VII and Thrombin-Antithrombin complexes were increased only in the patients with poor metabolic control (p < 0.01). Activated Partial Thromboplastin Time, Prothrombin Time, Antithrombin III, Protein C, Plasminogen, alpha 2-Plasmin Inhibitor, B beta 15-42 fibrin peptide were found to be in the normal range. Fibrinogen correlated positively with fasting blood glucose (p < 0.05) and Thrombin-Antithrombin complexes with glycosylated haemoglobin (p < 0.05), whereas Factor VII was positively correlated with glycemia (p < 0.01) and glycosylated haemoglobin (p < 0.05). Higher levels of Fibrinogen were found in patients affected by nephropathy (p < 0.005) or neuropathy (p < 0.05). These results demonstrate an impairment of the haemostatic balance in diabetic patients, that is a possible hypercoagulable state, which represents an important factor in the pathogenesis of atherosclerotic complications.

Adult↗
PubMed1992

Which method for quantifying "microalbuminuria" in diabetics? Comparison of several immunological methods (immunoturbidimetric assay, immunonephelometric assay, radioimmunoassay and two semiquantitative tests) for measurement of albumin in urine.

We have compared the chemical and clinical characteristics of an immunonephelometric assay (INA), two immunoturbidimetric assays (ITA) and two semi-quantitative methods with those of a solid-phase radioimmunoassay (RIA) for measurement of urinary albumin (UA) concentration in 136 diabetic patients. INA and RIA had similar accuracy, and provided comparable results. However, RIA has slightly greater sensitivity than INA, which is easier and faster. Good agreement was also found between RIA and the two ITA methods, although one of these overestimated RIA values in the low-medium range (5-30 mg/l) of urinary albumin. ITA seems suitable for initial screening of albuminuria in diabetic patients but more sensitive procedures (such as RIA and INA) seem preferable for measurement of UA concentrations in the normal range. The two semi-quantitative methods showed high sensitivity but poor specificity, because of the large number of false positive results. About 50% of diabetic patients "positive" by these methods did not have microalbuminuria. The utility of these methods is questionable, because many samples from diabetic patients need to be reassayed by a more specific and sensitive assay such as the RIA, INA or ITA methods.

Albuminuria↗
PubMed1992

Automated measurement of lactate dehydrogenase, alkaline phosphatase and gamma-glutamyltransferase in urines: an alternative to the manual procedure.

A sensitive and precise automated assay of urinary lactate dehydrogenase (EC 1.1.1.27), alkaline phosphatase (EC 3.1.3.1) and gamma-glutamyltransferase (EC 2.3.2.2) is described. For this purpose, we used a BM/Hitachi System 704 model and reagents for automated analysis of serum enzymes from Boehringer Mannheim. However, the schedules of enzyme chemistry parameters recorded by the autoanalyzer and the spectrophotometric calibration are reprogrammed to meet requirements deriving from urine adoption and to optimize the enzyme assay in this unusual medium.

Alkaline Phosphatase↗
PubMed1991

How can storage time and temperature affect enzymic activities in urines?

We measured a tubular brush-border enzyme (alanine aminopeptidase, AAP) and a lysosomal hydrolase (N-acetyl-beta-D-glucosaminidase, NAG) in morning urines from 15 healthy normal subjects to check if different storage times and temperatures could modify enzyme concentrations. Short-term (24 h) storage time at room temperature or 4 degrees C does not affect AAP and NAG activities. Both enzymes are well preserved at -70 degrees C. AAP dramatically falls after 1 month at -20 degrees C, lowering to about 8% of the initial value after only 4 days of storage. On the contrary, NAG is well preserved at these storage conditions. Centrifugation has revealed not critical for measurement of these two enzymes.

Acetylglucosaminidase↗
PubMed1991

Pharmacokinetic optimisation of oral hypoglycaemic therapy.

Two main classes of oral hypoglycaemic drugs, the sulphonylureas and the biguanides, are currently used in the therapy of type II, non-insulin-dependent diabetes mellitus (NIDDM). The basic pharmacokinetic properties of these agents are discussed with a view to efficient and safe treatment. Both first- and second-generation sulphonylureas are rapidly absorbed from the gastrointestinal tract. In the plasma compartment, these drugs are strongly bound to serum proteins. All sulphonylureas are metabolised in the liver, and the metabolites and the parent drugs are eliminated mainly in the urine, but also (second-generation derivatives) in the faces. Rapid- and short-acting sulphonylureas may improve early insulin release and promote better postprandial glucose control. Long-acting derivatives may ensure better control of overnight glycaemia. The elderly are at risk of developing severe sulphonylurea-induced hypoglycaemia, and in this population the agent chosen should have a short or intermediate duration of action and no active metabolites. Caution is needed when prescribing any sulphonylurea in patients receiving drugs known to affect sulphonylurea action, and in those with impaired liver and/or kidney function. The bioavailability of the biguanides ranges from 40 to 60%. Binding to plasma proteins is absent or very low. Metformin and buformin are not metabolised and are excreted in the urine; phenformin undergoes hepatic hydroxylation and is excreted in both urine and faeces. Metformin is the only agent of this class currently recommended for clinical use. The main indications of metformin treatment are NIDDM associated with obesity and/or hyperlipidaemia, and in combination with sulphonylurea both as primary treatment and when secondary failure occurs with sulphonylurea alone. Lactic acidosis may develop in patients receiving therapy with biguanides, especially in the presence of a preexisting contraindication to their use.

Administration, Oral↗
PubMed1991

Effects of storage time and temperature on urinary enzymes.

We measured three renal tubular brush-border enzymes (lactate dehydrogenase, LDH, EC 1.1.1.27; gamma-glutamyltransferase, GGT, EC 2.3.2.2; and alkaline phosphatase, AP, EC 3.1.3.1) in morning urine samples from 48 healthy subjects to check whether different storage times and temperatures could modify enzyme concentrations. Short-term (24 h) storage time at room temperature or 4 degree C does not affect urinary enzyme activity. A few days of freezing, at -20 or -70 degrees C, dramatically lowers LDH and AP values; GGT is partially preserved only at -70 degrees C, if the sample has been previously centrifuged. Urinary enzymes investigated in this study are extremely labile at low temperatures.

Alkaline Phosphatase↗
PubMed1979

Plasma levels of glucose and lactate after intravenous glipizide administration in some insulin-dependent diabetics. Therapeutic effects of an associated glipizide-insulin treatment.

A study was carried out to evaluate the effectiveness of glipizide in insulin-dependent diabetic patients. An intravenous glipizide (2 mg) test was carried out in 7 patients before and after a period of associated insulin-glipizide treatment (mean daily dose of 80.7 i.v. lente insulin and 14.3 mg glipizide for 9.1 months) to assess the capacity of the sulphonylurea to reduce acutely the plasma glucose and lactate levels. Glipizide did not produce glucose variations in either test but did result in a significant decrease, in the first test only, in mean plasma baseline levels of lactate, which were higher than normal in these patients. There was no reduction in daily insulin requirements after the period of associated glipizide-insulin treatment. It is concluded that, in the dosage used, intravenous glipizide probably has no hypoglycaemic effects in insulin-dependent diabetics. Moreover, it did not prove useful in combination with insulin. However, the reduction in plasma lactate may be related to an acute enhancement of the exogenously administered insulin. This improvement in the insulin effect may be an acute one among the so called "extra-pancreatic" actions which have been demonstrated for glipizide and other sulphonylureas.

Adult↗
PubMed1978

Kinetic analysis of plasma insulin disappearance in nonketotic diabetic patients and in normal subjects. A tracer study with 125I-insulin.

The studies so far reported on the metabolic clearance rate of insulin in human diabetes mellitus have given conflicting results, probably because they have been conducted on few patients and have used a variety of experimental techniques and data treatments. We investigated the kinetics of insulin distribution and degradation in 35 normal subjects and in 42 nonketotic, nonobese, overtly diabetic patients, of whom 26 were above 40 yr old and 16 were 40 yr old or less at diagnosis. The design of the study combined (a) the use of a tracer to perturb minimally the steady state and to avoid glucose infusion; (b) the preparation of purified [(125)I]-monoiodoinsulin, which has a metabolic behavior similar to that of native insulin; and (c) noncompartmental analysis of the plasma immunoprecipitable (125)I-insulin disappearance curves, which were recorded for 2 h after pulse i.v. injection of the tracer.Metabolic clearance rate was found to be similar in diabetics (404+/-18 ml/min.m(2), mean+/-SEM) and in normals (420+/-14), although the latter-onset patients had slightly, if not significantly, lower metabolic clearance rate values than the earlier-onset diabetics (385+/-19 and 443+/-36, respectively). The initial distribution volume of the hormone also did not significantly differ in diabetics and normals and was similar to plasma volume. The reentry rate into the initial distribution volume of the hormone and the total, plasma-equivalent distribution volume of insulin were both significantly raised in diabetics (251+/-12 ml/min.m(2) and 10.3+/-0.5 liters/m(2)) in comparison with normals (195+/-8 and 7.5+/-0.3). The posthepatic delivery rate of insulin was found to be slightly raised in later-onset diabetics (194+/-20 mU/h.m(2)), but somewhat reduced in earlier-onset diabetics (133+/-15) in comparison with normals (172+/-14); these differences reflected the different basal plasma insulin concentrations in these three groups. Chronic treatment with oral hypoglycemic drugs, age, duration of the disease, and degree of metabolic control appeared to have only little effect on the kinetics of insulin.On the basis of these results, we conclude that insulin-independent adult diabetics show, already in the fasting state, a combination of insulin resistance and insulin deficiency and a derangement in insulin distribution, the precise significance of which is uncertain.

Adult↗
PubMed1978

[125I]hGH metabolism in acromegaly: effects of chronic treatment with 2-Br-alpha-ergocryptine.

To assess the effects of 2-Br-alpha-ergocryptine (CB-154 Sandoz) on hGH metabolism, six acromegalic women were studied before and after 2 months of treatment with 10 mg bromocriptine/day. GH kinetics were evaluated by noncompartmental analysis of the plasma disappearance curve of immunoprecipitable [125I]human GH after pulse administration of the labeled hormone. MCR was increased in all acromegalics after treatment; the difference between the means [153 +/- 11 vs. 200 +/- 16 ml/min . m2 (mean +/- SE)] was highly significant. Secretion rate (SR), measured as the product of MCR by integrated 12-h concentration, was decreased in four patients after treatment, while it was slightly increased in the other two. No change was found after treatment, either initial distribution volume [2.0 +/-0.1 before (B) vs. 2.1 +/- 0.1 liters/m2 after (A)] or total distribution volume [5.0 +/- 0.3 (B) vs. 5.4 +/- 0.4 liters/m2 (A)]. Diffusion of GH from the intravascular pool, measured as reentry rate, was unchanged with treatment [66 +/- 4 (B) vs. 76 +/- 11 ml/min . m2 (A)]. In conclusion, our study shows that in acromegaly, by increasing the MCR of the hormone, and 2) by reducing the SR. The mechanisms by which bromocriptine increased MCR of the GH are also suggested on the basis of kinetic results; like dopamine, bromocriptine could induce a redistribution of blood flows to different organs, thus resulting in a net increase of blood flow to the liver and kidneys which are the major catabolic sites of GH.

Acromegaly↗