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M Cigolini

Publications and source records attributed to M Cigolini.

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

Indicators of fat distribution, serum lipids, and blood pressure in European women born in 1948--the European Fat Distribution Study.

In the spring of 1986, the authors studied the relation between body mass index and anthropometric indicators of fat distribution to cardiovascular risk factors (serum lipids and blood pressure) in approximately 450 women aged 38 years randomly selected from population registers in five European centers. Waist circumference was, in univariate analysis, more strongly related to triglycerides (positive association) and high density lipoprotein (HDL) cholesterol (negative association) than to body mass index or any other anthropometric measurement. Among the centers, we observed considerable variation in the strength of the associations between anthropometric measurements and risk factors. After adjustment for body mass index, most associations between skinfolds and circumferences and risk factors were reduced to statistically nonsignificant levels, but in some centers there were independent contributions of circumferences or circumference ratios to serum lipids, but not to blood pressures. Adjustment for differences in body mass index and fat distribution between the centers did not reduce the differences in cardiovascular risk factors between the different centers but instead revealed that serum cholesterol levels were lowest in the centers of southern Europe (Italy) and that HDL cholesterol levels were higher. Blood pressure was highest in the Swedish women. We conclude that in some female populations, but not in others, indicators of fat distribution are related to serum lipids but not to blood pressure, independent of body mass index.

Adipose Tissue↗
PubMed1989

Estimates of in vivo insulin action in man: comparison of insulin tolerance tests with euglycemic and hyperglycemic glucose clamp studies.

We compared estimates of in vivo insulin action derived from insulin tolerance tests (ITT) and euglycemic and hyperglycemic glucose clamp studies in 17 normal subjects and 19 patients with various diseases characterized by insulin resistance. Fifteen subjects underwent an ITT and a euglycemic clamp study, 17 subjects underwent an ITT and a hyperglycemic clamp study, and 4 subjects underwent all 3 tests. The ITT consisted of a bolus iv injection of regular insulin (0.1 U/kg BW). The plasma glucose disappearance rate during the 3- to 15-min period following the insulin injection was taken as a measure of insulin action. In both euglycemic and hyperglycemic clamp studies, which were carried out with standard techniques, the ratio between the amount of glucose infused to maintain glycemia at the desired level and the mean plasma insulin concentration from 60-120 min (M) (euglycemic clamp studies) or 20-120 min (I) (hyperglycemic clamp studies) was used as a measure of insulin action. A close correlation was found between plasma glucose disappearance rate and the M/I ratio during either the euglycemic (r = 0.811; P less than 0.001) or the hyperglycemic (r = 0.826; P less than 0.001) clamp studies. These results suggest that the 15-min ITT is suitable as a simple and rapid estimation of in vivo insulin action when glucose clamp studies are not feasible, as in large series of subjects or serial studies.

Adult↗
PubMed1988

Differences in glucose metabolic enzyme activities in human adipose tissue from abdominal and gluteal regions.

In order to verify whether intersite differences exist in glucose metabolism of subcutaneous human adipose tissue, basal and insulin-stimulated 14C-1-glucose incorporation into triglycerides and the activities of some enzymes of glucose disposal were tested in abdominal and gluteal adipose tissue of 31 nondiabetic obese otherwise healthy women during isocaloric diet and after 2 weeks of very-low-calorie-protein-sparing modified diet. Basal 14C-1-glucose incorporation into triglycerides was quite similar in the adipose tissue of the two sites, and it was not influenced by dietary restriction. Insulin stimulated this metabolic activity to the same extent in both sites during isocaloric diet; after hypocaloric diet this effect of insulin was slightly decreased in adipose tissue of the abdominal site and completely abolished in the gluteal site. No enzymatic activity was different between the examined subcutaneous regions during the isocaloric diet; after very-low-calorie intake, hexokinase activity decreased in both sites, once again more markedly in the gluteal one; glucose-6-P-dehydrogenase activity decreased in the adipose tissue of the gluteal region only. These data suggest that glucose metabolism of the adipose tissue of the gluteal region is particularly decreased by severe calorie restriction. Therefore, since lipolysis does not occur at a higher rate in gluteal adipose tissue during calorie restriction, this tissue seems to undergo a resting metabolic phase during hypocaloric diet.

Abdomen↗
PubMed1988

Regional obesity and serum lipids in European women born in 1948. A multicenter study.

In five different cities in four European countries, women born in 1948 were randomly selected. Anthropometric measurements (i.e. circumferences and skinfolds) were taken. Serum lipids were determined in one laboratory. Different levels of waist circumferences gave different averages and distribution of waist/hip ratio, which confirms the need of precise standardization of these measurements. Women in southern parts of Europe were more overweight than in Northern Europe (partly due to selection bias in Naples) and, when adjusted for that, southern women had a more central distribution of fat (higher waist/thigh, lower triceps/subscapula). When data were pooled, circumference ratios were positively correlated with triglycerides and total cholesterol and negatively with HDL cholesterol. Occupation of husband and body mass index were associated with fat distribution and triglycerides and HDL cholesterol. In multiple regression fat distribution was still correlated with serum lipids but differences in serum lipids between countries did not diminish.

Adult↗
PubMed1987

Effects of noradrenaline exposure on rat brown adipocytes in cultures. An ultrastructural study.

Adipocytes in intact brown adipose tissue show multivacuolar lipid deposit and mitochondria of 'typical' morphology. Cultured brown adipocytes retain the multivacuolar lipid deposit, while 'typical' mitochondria degenerate and 'atypical' organelles appear instead of the former. Since evidence exists that catecholamines deeply influence brown adipose tissue morphology and function in vivo, we undertook the present ultrastructural investigation to assess whether exposure of cultured brown fat cell to noradrenaline could prevent (or induce regression of) the in vitro morphological modifications of brown adipocytes. Brown adipocytes cultured for 8 h in the presence of noradrenaline (5 X 10(-5) M) had a larger mitochondrial area (i.e. a larger percentage of cytoplasm occupied by non-degenerating mitochondria) in comparison with control cells, as assessed by morphometry; this was due to larger number of mitochondria in noradrenaline-treated cells. Moreover, a number of cells with mitochondria strictly resembling those of the intact tissue were visible in noradrenaline-treated cultured after 8 hr, while 'typical' mitochondria were no longer observed in parallel control cultures. After 5 days of culture without hormone addition, exposure to noradrenaline (5 X 10(-5) M) did not induce quantitative modifications of 'atypical' mitochondria or changes of their ultrastructure up to 12 hr. However, reduction in size of the lipid deposit and activation of both rough endoplasmic reticulum and Golgi apparatus were evident in noradrenaline-treated adipocytes in comparison with non-treated cells.

Adipose Tissue, Brown↗
PubMed1987

Brown adipose tissue: a scanning electron microscopic study of tissue and cultured adipocytes.

The ultrastructure of rat brown adipose tissue (BAT) and of adipocytes cultured from BAT were studied by scanning electron microscopy (SEM). Brown adipocytes in the intact tissue were arranged in lobules with bundles of collagen among them; within each lobule 20- to 40-microns-large adipocytes were packed together. Fibers of reticular collagen enveloped each adipocyte and also connected each cell to vessels and nerves. At the adipocyte surface rounded protrusions were present, which corresponded to the BAT-typical multivacuolar lipid depot. Gradual digestion of the stroma with collagenase disclosed a more delicate, felt-like cover surrounding each adipocyte, probably representing the external lamina of the cell. Complete digestion of the stroma showed a smooth plasmalemma with occasional roundish blebs which varied in size. Cultured (24 h) brown adipocytes from the stromal-vascular fraction of BAT were elongated or polygonal in shape, with a flattened, central nucleus and a number of spherical cytoplasmatic inclusions which have the same dimension and location as lipid droplets. These inclusions were arranged either at cellular poles or around the nucleus; this suggests that brown adipocytes with mature features were present in the culture. Pictures suggesting the detachment of lipid droplets from the cell body were also visible. Lipid droplet extrusion could be a complementary mechanism which might explain the rapid delipidation of brown adipocytes in culture.

Adipose Tissue↗
PubMed1987

Metformin enhances insulin binding to "in vitro" down regulated human fat cells.

Insulin binding to human adipose tissue from surgical patients was determined after three different preincubation conditions: a) 24 hrs in the presence or absence of 80 ng/ml insulin; b) 24 hrs in the presence of 80 ng/ml insulin or insulin plus 4 micrograms/ml metformin; c) 48 hrs pre-incubation as in b). We found that insulin down regulated its own receptor after 24 hours pre-incubation; when metformin was present in the pre-incubation medium together with insulin, insulin binding to adipose tissue was significantly higher than in tissue exposed to insulin alone after 48 hrs pre-incubation; a similar effect of metformin was already seen after 24 hrs, but was not statistically significant. We suggest that metformin can correct down regulation of the insulin receptor. This finding could explain discrepant results among studies dealing with the influence of metformin on insulin binding. Moreover, these results could be useful in understanding the mechanism of action of metformin in insulin-resistant states, e.g. type II diabetes.

Adipose Tissue↗
PubMed1986

Effect of insulin on lipolysis in adipose tissue of rats of different ages.

Several authors have not been able to find any antilipolytic effect of insulin in adipose tissue "in vitro". We investigated the possible role of cell size and/or age of donors on this phenomenon. The lipolytic rates (glycerol release per cell) were lower in the small cells of the 4-6 weeks old rats than in the larger cells of the 25-30 weeks old animals; however, the difference disappeared when the data were expressed per unit of cell surface area. Insulin (0.5-50 ng/ml) failed to inhibit both maximally and submaximally noradrenaline stimulated lipolysis in the adipocytes of the young rats, but its antilipolytic action was fully restored by using glucose-free medium. Therefore, at our experimental conditions, a glucose dependent factor, possibly involving the preferential hydrolysis of newly synthetized triglycerides, seems to blunt or to mask the insulin induced inhibition of glycerol release. Relatively higher rates of glucose metabolism and a lower lipolysis in small fat cells might explain the difference in the action of insulin on glycerol release in the adipose tissue of young rats as compared to the older ones.

Adipose Tissue↗
PubMed1986

Isolation and ultrastructural features of brown adipocytes in culture.

Interscapular brown adipose tissue was removed from young rats, the cells isolated using collagenase, pelleted by centrifugation and cultured. Ultrastructural observations were made on these cells immediately after isolation and on Days 1, 2, 4, 10 and 14 of culture. The isolated cells show the typical submicroscopic features of cells in intact brown adipose tissue, i.e. a multivacuolar lipid depot and numerous typical mitochondria with dense cristae. However, as early as Day 1 of culture, the cells show degeneration of the typical mitochondria which are probably then extruded from the cells. Atypical mitochondria now begin to appear and become dominant on Day 4 of culture. By contrast, the typical multivacuolar shape of the lipid droplet does not change. Not even after prolonged periods of culture (2-4 weeks) is there any evidence of coalescence of the multivacuolar lipid depot. These findings are consistent with the possibility that the typical mitochondria of brown adipocytes depend on in vivo conditions, perhaps adrenergic innervation, while the multivacuolar characteristic of the lipid depot does not, and may be an intrinsic feature of the brown adipose cell.

Adipose Tissue, Brown↗
PubMed1986

Ultrastructure of brown adipocytes mitochondria in cell culture from explants.

Brown adipocytes lose in culture their typical mitochondria, which are replaced by others of non typical morphology. During studies aimed at clarifying this phenomenon we found that better preservation of the 'typical' mitochondrial morphology is obtained in vitro after a long period of time, when cells from small fragments (explants) of brown adipose tissue (BAT) are cultured instead of collagenase-isolated brown adipocytes. These results suggest that the explant technique could be better suited to study brown adipocytes in culture than other methods employing collagenase-isolated cells.

Adipose Tissue, Brown↗
PubMed1985

Human brown adipose cells in culture.

Brown adipose tissue (BAT), obtained from the axillary and perirenal regions of newborns 24-48 h after death, was digested with collagenase and the free cells were cultured. Only the cultures of cells from tissue obtained later than 24 h post mortem were successful. These cells grew slowly to reach confluence. Their typical mitochondria gradually disappeared, being replaced by untypical mitochondria. After confluence, the cells accumulated large amounts of lipid in non-coalescent multivacuolar depots. This model can be useful for the study of the metabolic and morphological features of human brown fat cells.

Adipose Tissue, Brown↗
PubMed1985

An ultrastructural study on muciparous microcysts of the human adenohypophysis.

The microcysts found in two adenohypophyses removed from patients with nonsecreting adenomas of this gland have been studied. In one case the cysts were completely surrounded by neoplastic tissue, whereas in the second they were located within the normal parenchyma. The cysts were surrounded by a basement membrane, and appeared to contain a finely granular weakly electron-dense substance. Their walls were lined by mostly cubic cells with microvilli, joined by junctional complexes. Intracytoplasmic microlumina could be seen in some of these cells. Cells showing cilia with a 9 + 2 fibrillar pattern and cells with mucosecretory differentiation were also present. Furthermore endocrine cells were also found in the cyst-lining epithelium. The ultrastructural aspects of the cyst cells lead to reject the hypothesis that these are derived from folliculostellate cells. Besides, intermediate aspects between cyst cells and tumor cells were never visible. Therefore it seems likely that a relationship between adenoma and cyst cells does not exist and that cyst cells originate from remnants of Rathke's pouch with a ciliate or mucosecretory differentiation. The presence of endocrine cells in the cyst-lining epithelium deserves further study, for it seems to indicate that an endocrine differentiation may occur in the adult, too. To our knowledge this is the first ultrastructural study of these structures in adult human pituitary gland.

Adolescent↗
PubMed1985

An ultrastructural study of adipocyte precursors from epididymal fat pads of adult rats in culture.

It has been demonstrated that cells with poor or no lipid content, isolated from epididymal fat pads of young rats, develop fully into mature adipocytes in vitro. The ultrastructural feature of these cells during such a development have been studied recently. In the present work the electron microscopic aspects of similarly obtained cells from adult rats have been investigated. It has been found that no morphological differences are present in the cells immediately after isolation between young and adult rats. During culture the cells from both adult and young rats show the same maturative process, but in adult rats this process is generally slower and not homogeneous, suggesting the presence of two populations of adipocyte precursors. The former accumulate lipids quickly and have electron microscopic features very similar to those observed for young rat precursors, however maturation is still faster in the latter cells. The latter have electron microscopic aspects of less differentiated cells (some fibroblast-like features) during the first days of culture; however they show a similar development when longer culture periods are studied. These data suggest that the fibroblast-like cells seen after a period of time in culture probably represent an early stage of adipocyte precursor differentiation. Thus it is suggested that in adult mammals, there may be a population of adipocyte precursors present within the adipose tissue which upon stimulation by as yet unknown factors would develop fully into adipocytes.

Adipose Tissue↗
PubMed1984

Cells in human adipose tissue developing into adipocytes.

Sedimentable cells from human adipose tissue of different origins were cultured under conditions when cell multiplication was prevented but lipid filling optimized (suspension culture). In this way an estimation was obtained of the number of in vivo determined adipose precursor cells (preadipocytes) which were not filled with lipid. Under these conditions no cells from adult, non-obese subjects developed to adipocytes. Cells developing to adipocytes constituted less than 0.02% and 1% of adipocytes in tissues from obese adults and from children, respectively. It was concluded that in vivo determined adipocyte precursor cells (preadipocytes, lipid-free fat cells) are not present in a significant number in human adipose tissue either from adults or from children as tested with the method employed, allowing detection of a large number of such cells in adipose tissue from small rats.

Adipose Tissue↗
PubMed1984

Lack of effect of intravenous metformin on plasma concentrations of glucose, insulin, C-peptide, glucagon and growth hormone in non-diabetic subjects.

A study was carried out to evaluate the acute effect of an intravenous injection of metformin on the fasting plasma concentrations of glucose, insulin, C-peptide, glucagon and growth hormone in 15 non-diabetic subjects. Metformin (1 g) was administered as a bolus in a peripheral vein and blood was sampled 2, 5, 10, 15 and 30 minutes after the drug injection. No significant change in fasting concentration of glucose nor in C-peptide, insulin, glucagon and growth hormone fasting levels was noticed. It is concluded that metformin does not possess an acute direct hypoglycaemic effect in non-diabetic subjects and does not acutely affect the basal activity of endocrine pancreas and pituitary gland in releasing insulin, glucagon and growth hormone.

Adult↗
PubMed1984

A morphological study of the adipocyte precursor.

In order to attempt to characterize the adipocyte precursor cell in situ in developing adipose tissues from young rats, the light and electron microscopic characteristics were determined of cells in situ in these tissues, as well as in suspensions from the same tissues of cells liberated with collagenase subsequently developing to adipocytes in culture. The functional characteristics of adipose precursor cells at different stages of development in culture is known from previous work, and could therefore be added in parallel to the morphological characteristics. In order to allow comparison with fibroblasts from a site where adipocyte formation does not occur, lung-fibroblasts were also studied in parallel cultures. In culture, a rapidly dividing cell confluenced and reached full expression to adipocytes. This cell had morphological characteristics developing at the same time as early lipid accumulation making it easily distinguishable from a lung fibroblast in culture. A similar cell was found in abundance in the peripheral, non-developed part of the intact epididymal fat pad, here often surrounded by collagen. However, the early preadipocyte (without lipid droplets) and the adipoblast cannot be morphologically distinguished in situ from the fibroblast; therefore it cannot be excluded that fibroblasts and adipoblasts are the same cells in adipose tissue, possibly deriving from the pericyte.

Adipose Tissue↗
PubMed1984

Adipose tissue lipoprotein-lipase activity in obesity.

The activity of lipoprotein-lipase in heparin-eluates of adipose tissue (AT-LPLA) of three body regions was measured in 22 obese and 18 nonobese females under basal conditions. AT-LPLA in the obese women both before and after 10 d of caloric restriction was also measured. Basal LPLA correlated well with plasma insulin values and reduced significantly after caloric restriction. Relative body weight, body fat, fasting and glucose-stimulated insulin levels, triglycerides, total cholesterol, but not high-density lipoprotein cholesterol, significantly decreased after caloric restriction. Variation of insulin levels after caloric restriction was the best explanatory variable correlating with AT-LPLA variations. These results are consistent with a primary role of insulin in regulating AT-LPLA.

Adipose Tissue↗