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Biomedical subjects

M Monti

Publications and source records attributed to M Monti.

At least 199 records · Page 11Linked to original sources
PubMed1987

Reduced thermogenesis in muscle and disturbed lipoprotein metabolism in relation to thyroid function in haemodialysis patients.

Muscle thermogenesis, measured by direct calorimetry on resting biopsy samples, was studied in 28 haemodialysis patients and related to thyroid function variables, plasma lipoprotein concentrations and post-heparin lipase activities. The heat production was decreased in about 40% of the patients and significantly correlated with total thyroxine and free thyroxine index. In addition to a slight to moderate hypercholesterolaemia comparable to that found in subclinical hypothyroidism, the patients had also hypertriglyceridaemia in combination with low lipoprotein lipase activity and impaired fat tolerance. The latter abnormalities were related to the lowered muscle heat production values. The pattern of changes may represent a biological adaptation to the systemic illness for conservation of energy.

Adult↗
PubMed1987

Erythrocyte metabolism in hyperthyroidism: a microcalorimetric study on changes in the Embden-Meyerhof and the hexose monophosphate pathways.

Erythrocyte metabolism was studied in vitro by microcalorimetry in 10 hyperthyroid subjects before and after treatment. By inhibiting the enzyme enolase in the Embden-Meyerhof pathway with sodium fluoride (NaF) we have recorded the anaerobic and aerobic contributions in erythrocyte thermogenesis. The decrease in heat production rate in samples with NaF corresponds to the anaerobic contribution, whereas the values from samples with NaF reflect aerobic processes. Before treatment, total heat production rate was 120 +/- 2 mW/l erythrocytes which was higher than the post-treatment value of 99 +/- 2 (P less than 0.001) as well as the value for 14 euthyroid subjects, 108 +/- 2 mW/l (P less than 0.001). The NaF inhibitable rate was 73 +/- 2 before and 63 +/- 1 mW/l after therapy (P less than 0.01). These values correspond to 61 +/- 1 and 64 +/- 1% (n.s.) of the total heat production rate, and were similar to that of 61 +/- 2% for the controls. Heat production rates in the presence of NaF were 47 +/- 1 before and 36 +/- 1 mW/l after therapy (P less than 0.001), representing 39 +/- 1 and 36 +/- 1% of total values, respectively. The present results show that overall metabolism is increased in erythrocytes from hyperthyroid subjects before treatment and returns to normal after normalization of the thyroid function. Moreover, by using microcalorimetry we found that the metabolic activity along the Embden-Meyerhof anaerobic pathway as well as along the hexose monophosphate aerobic pathway in erythrocytes is stimulated by thyroid hormones.

Adult↗
PubMed1986

Microcalorimetric investigation of metabolism in rat hepatocytes cultured on microplates and in cell suspensions.

In the present work, heat production rate in rat hepatocytes has been measured by use of thermopile heat conduction calorimeters. Both hepatocytes cultured in monolayers on microplates and hepatocytes in suspensions were used for microcalorimetric measurements. The highest heat production rate was found in newly cultured cells; thereafter, a gradual decrease was noted. After 1 day of culture, metabolic activity had reached a steady state that lasted about 4 days. A cell-density dependence of heat production was found, both in cell suspensions and in cultured hepatocytes on microplates. Higher cell concentration in the calorimeter ampoule was accompanied by decreasing heat production per cell. The heat output recorded for hepatocytes cultured on microplates (25 X 10(3) cells) was found to be 0.327 +/- 0.13 nW per cell after 24-48 h. Addition of sodium azide and sodium fluoride to tissue culture medium reduced heat production rate in cultured hepatocytes by 60 and 20%, respectively. Recording of heat production with the present calorimetric technique is relatively simple and fast, and offers the possibility to perform measurements in small samples of cultured hepatocytes on microplates, thus allowing long-term as well as repeated measurements on the same cell population.

Animals↗
PubMed1986

A microcalorimetric study of heat production in resting skeletal muscle from human subjects.

Different microcalorimetric techniques have been compared for the assessment in vitro of the total metabolic activity of resting skeletal muscle. Human fibre bundles were suspended in Krebs-Ringer-phosphate buffer containing glucose and insulin and the heat evolution was continuously monitored for 2-6 h. Palmitate as substrate was also tested. The power signals declined rapidly when a static calorimetric method (A) was used. Two different perfusion methods (B, C) gave higher power values. Long-lasting steady states were observed with method C, where the sample was contained in a cage acting as a stirrer. Significant differences were found for fibre bundles from different human muscles as well as age- and sex-related differences. The heat production in samples from the rectus abdominis muscle (method B), 0.73 mW/g muscle wet wt., was significantly higher than for the obliquus internus muscle, 0.44 mW/g, and the vastus lateralis muscle, 0.55 mW/g, but not different from the heat production value of vastus medialis, 0.66 mW/g. In method C particularly, the fibre bundles are believed to be in adequate contact with the surrounding medium. With the use of a multi-channel calorimeter it is possible to perform up to four experiments simultaneously, e.g. involving the calorigenic effects of pharmacological substances. The technique provides a new approach for detailed studies of muscle metabolism in physiological and pathological conditions.

Adolescent↗
PubMed1986

Thermogenesis in human skeletal muscle as measured by direct microcalorimetry and muscle contractile performance during beta-adrenoceptor blockade.

The influence of beta-adrenoceptor-blockade on skeletal muscle was studied in ten healthy males with propranolol, atenolol and pindolol randomly given for 8 days each in a cross-over double blind test. After 7 days on each drug, muscle function was tested by an isokinetic dynamometer. Thermogenesis in biopsy samples taken from vastus lateralis muscle after a low grade exercise was studied after 8 days on each drug by direct calorimetry with a perfusion microcalorimeter. Before drug administration, a median heat production rate of 0.67 mW/g of muscle was measured. This value was significantly reduced by 25% during propranolol, but no significant change was found during atenolol or pindolol administration. Peak torque decline during isokinetic endurance test changed significantly in knee flexor but not in extensor muscles, from 15% to 27% after propranolol and from 15% to 23% after pindolol. Maximum dynamic strength was unaltered. Our data suggest that blockade of sympathetic beta 2-receptors decreases thermogenesis in human skeletal muscle and impairs isokinetic endurance.

Adolescent↗
PubMed1986

Use of TPA in hepatology of infectious nature. Initial observations.

The tissue polypeptide antigen, TPA, is a tumour-associated antigen which is synthesized during the S phase of cellular division and released later by the tissues when rapid growth takes place. For this reason, the TPA is considered to be a specific phase tumour-associated antigen. Since Björklund detected the antigen in 1957 much less has been written about research into the presence of the TPA in high concentration in the blood of subjects with tumours in different sites. The TPA can, however, be measured in moderate quantities in healthy individuals and in those with hepatic pathology (hepatitis and cirrhosis) and pathology of a viral nature. In hepatic parenchymal pathology, repeated measurements of this marker show normalization with the benign course of the disease. The aim of this work is to evaluate if the use of the TPA can be useful in hepatology of an infectious nature as an index of cytoreproduction, a phenomenon which often affects the hepatocytic cytolysis which is found in acute viral hepatitis.

Alanine Transaminase↗
PubMed1986

Methylxanthines reduce in vitro human overall platelet metabolism as measured by microcalorimetry.

The effect in vitro of caffeine, theophylline and enprofylline on overall platelet metabolism was investigated by a sensitive microcalorimetric method. Platelet heat production rate was found to be decreased significantly in the presence of any of the three methylxanthines in mM concentrations. Also lower caffeine concentration, as occurring during normal coffee intake, reduced platelet metabolism. These results show that, firstly, methylxanthines have a direct influence on platelet metabolism, and secondly, microcalorimetry can be used as a new and sensitive tool for investigating the influence of drugs on blood cell metabolism.

Blood Platelets↗
PubMed1986

Microcalorimetric studies on the effect of adenosine receptor agonists and xanthine derivatives on overall metabolism in human platelets.

The direct overall metabolic effects of drugs acting on adenosine receptors in human platelets were evaluated using a sensitive microcalorimetric method. Adenosine induced a concentration-dependent increase in the heat production rate at concentrations above 100 microM. The adenosine uptake inhibitor, dipyridamole (3 microM) did not modify the effect of adenosine. Two putative adenosine receptor agonists were tested: NECA (5-N-ethyl carboxamide adenosine) and PIA (L-N6-phenylisopropyl-adenosine). NECA induced, at significantly lower concentrations than adenosine, an enhanced heat production rate. Concentrations above 1 mM had no effect. PIA, on the other hand, invariably induced a reduction in the heat production rate already at a concentration of 100 microM. The two xanthine derivatives enprofylline (25 microM) and theophylline (100 microM) were tested at concentrations found during antiasthmatic therapy. Neither had any thermogenic effect by themselves nor showed any significant modification of the heat production rate induced by adenosine (300 microM). These results indicate that adenosine and NECA increase human platelet metabolism, whereas PIA has an opposite effect. The proposed adenosine receptor antagonists enprofylline and theophylline were without effects. This microcalorimetric study gives new insights into the complex nature of adenosine mechanisms in a human test system and indicates that the thermogenic effect of adenosine is unrelated to adenosine receptors.

Adenosine↗
PubMed1986

A freeze-fracture study of the enteropathy associated with dermatitis herpetiformis: a comparative investigation with coeliac disease.

Jejunal biopsies from patients with either dermatitis herpetiformis or coeliac disease were freeze-fractured and compared with normal jejunal biopsies. The intestinal mucosa of the normal biopsies showed a normal structure, with well-developed and tightly packed microvilli; in dermatitis herpetiformis and coeliac disease degenerative changes of the intestinal mucosa occurred. These changes appeared to be segmental in dermatitis herpetiformis and diffuse in coeliac disease. Emphasis is placed on changes in the tight junctional net at the base of the microvilli, which could represent cellular damage related to increased intestinal permeability to macromolecules in these diseases. An interpretative hypothesis for these observations is presented.

Biopsy↗
PubMed1986

Microcalorimetric investigation of cell metabolism in tumour cells from patients with non-Hodgkin lymphoma (NHL).

The overall metabolism in tumour cells from 36 untreated patients with non-Hodgkin lymphoma was evaluated by direct calorimetry. For 20 patients with lymphoma of high grade malignancy the median value of heat production rate per tumour cell was 3.9 pW and for 16 patients with low grade lymphomas the corresponding value was 2.8 pW. The difference between the two morphological groups is significant (p = 0.05). The median value of heat production rate per tumour cell from 13 patients who died within 2 yr after diagnosis was 4.0 pW. The corresponding value for 17 patients who have survived for more than 2 yr was 2.5 pW. The difference between the two groups is significant (p = 0.02). A high correlation was found between heat production rates in tumour cells and survival of the patients (p = 0.006).

Adult↗
PubMed1986

Controlled clinical trial of imidazole.2-hydroxybenzoate (ITF 182) versus sulindac in patients with rheumatoid arthritis.

The efficacy and safety of the nonsteroidal anti-inflammatory drugs imidazole.2-hydroxybenzoate and sulindac were compared in 30 patients with classical or definite rheumatoid arthritis. The trial was designed as a randomized parallel-group study comprising 15 patients given imidazole.2-hydroxybenzoate and 15 given sulindac orally for 28 days. Patients in both groups improved significantly in almost all of the variables evaluated. Imidazole.2-hydroxybenzoate was more effective than sulindac on Ritchie's articular index, left hand proximal interphalangeal joint circumference, erythrocyte sedimentation rate, and C-reactive protein. The incidence of side effects was significantly higher in patients treated with sulindac.

Adult↗
PubMed1986

Adipocyte heat production before and after weight reduction by gastroplasty.

Fifteen grossly obese patients were studied before and 6-8 months after gastroplasty. Their mean body weight decreased by 30% (from 127 +/- 13 to 97 +/- 14 kg, mean +/- SD). The preoperative hyperinsulinemia, hyperglucosemia and hyperglucagonemia were significantly reduced at follow up. Liproprotein lipase activity, measured in post-heparin plasma, was slightly reduced and did not change after weight reduction. Variables reflecting thyroid function were within the reference ranges; small but statistically significant reductions in serum thyroxine and reverse triiodothyronine levels were recorded. Adipocyte heat production, reflecting total cellular metabolic activity and registered by microcalorimetry, was significantly decreased before surgery (by about 60 per cent when expressed per g tissue and by about 20 per cent when expressed per cell) and increased significantly at follow-up; expressed per cell, the heat production was normalized, but expressed per g tissue the values were still about 15 per cent before those of a control group. The results indicate that the reduced adipocyte heat production in obese individuals is a consequent rather than a cause of severe obesity.

Adipose Tissue↗
PubMed1986

[Depression in alcoholic patients].

Eighty-six alcoholic patients in hospital (average age: 44 years, range: 24-60), were evaluated with the Hamilton Scale for depression and it turned out that 57% were non-depressed alcoholic patients and 43% were depressed alcoholic patients, this being a statistically significant difference. In addition, personal and demographic data was obtained which contributed to the object of the study.

Adult↗
PubMed1986

Caffeine stimulates in vivo overall cell metabolism. Microcalorimetric measurement of heat production in human platelets.

The influence of caffeine on overall cell metabolism was studied in human platelets by measurement of cell heat production rate. One hour after administration of 100-200 mg of caffeine, corresponding to 1-2 cups of coffee, significantly increased values (p less than 0.001) were found, 12 +/- 7%. A return to normal values was noted 1 hour later. The cell metabolic stimulation is presumably due to increased catecholamines. A temporary significant rise in systolic (p less than 0.02) and diastolic (p less than 0.05) blood pressure was observed 1 hour after ingestion of caffeine.

Adult↗