Biomedical subjects

D Boeri

Publications and source records attributed to D Boeri.

At least 19 recordsLinked to original sources

PubMed2003

Heat-shock protein 70 favours human liver recovery from ischaemia-reperfusion.

BACKGROUND: Pringle's manoeuvre controls excessive bleeding, but results in ischaemia-reperfusion injury during liver surgery. Activation of the heat-shock protein system of cell defense has been demonstrated after ischaemia-reperfusion injury in animal tissues. The aim of the present study was to determine whether the ischaemia-reperfusion accompanying hepatic surgery induces heat-shock protein 70 (HSP70) in human liver and whether the induction of HSP70 is related to the recovery of liver function. METHODS: Heat-shock protein 70 and gamma-actin mRNAs were assayed in the liver biopsies of 10 subjects undergoing partial hepatectomy for localized lesions. Measurements were performed before the Pringle's manoeuvre and at the end of the surgery. Transaminases and fibrinogen were measured before and at 12, 24 and 36 h following hepatectomy. RESULTS: After an average 40 +/- 8-min period of warm ischaemia, a significant increase of HSP70 mRNA (187 +/- 67%, 2P < 0.05) was observed. The acute increase of HSP70 mRNA correlates with the decrease of transaminases (AST: rs -0.964, ALT: rs -0.891, P < 0.002) and the increase of fibrinogen (rs -0.7, P < 0.02) observed between 12 and 24 h following surgery. CONCLUSIONS: Heat-shock protein 70 is induced by ischaemia-reperfusion injury in human liver. Its induction seems to have beneficial effects, including a prompt reduction of transaminases and a rapid recovery of fibrinogen synthesis.

Analysis of Variance↗

PubMed2001

Increased prevalence of microthromboses in retinal capillaries of diabetic individuals.

In diabetic retinopathy, capillary nonperfusion and eventual obliteration can lead to retinal ischemia and sight-threatening neovascularization. The occurrence of retinal microthrombosis in human diabetes has long been suspected and occasionally observed but never systematically demonstrated. We used trypsin digestion to isolate the intact vascular network from retinas obtained postmortem from nine diabetic donors (age 64 +/- 11 years, duration of diabetes 6 +/- 4 years; mean +/- SD) and eight age-matched nondiabetic donors. Topographically matched sectors (each one-sixth of retina) of diabetic and nondiabetic retinas were tested sequentially with antibodies to fibrin cross-linking factor XIII and platelet glycoprotein (GP)-IIIa to identify fibrin-platelet thrombi. In some trypsin digests, we also examined vascular cell apoptosis. The retina from a nondiabetic donor, 24 years of age, who had died of trauma, was used to exclude confounding influences caused by the postmortem period. When compared with those of nondiabetic donors, the retinas of diabetic donors showed double the number of capillary segments with colocalized immunostaining for factor XIII and GPIIIa (P = 0.02). The total area of the positive segments was fourfold greater in the diabetic than in the nondiabetic donors (P = 0.02) and correlated with the duration of diabetes (r = 0.71, P < 0.05). Large thrombi were six times more frequent in the diabetic donors (P = 0.03), and there was a significant topographical association of microthrombosis with apoptotic cells in both diabetic and nondiabetic vessels (P = 0.0001). Hence, diabetes of short duration was found to be associated with a greater than normal number and size of platelet-fibrin thrombi in the retinal capillaries. These thrombi can contribute to capillary obliteration and retinal ischemia and may be a practical target for early drug intervention.

Adult↗

PubMed1998

Intrarenal arteriosclerosis and impairment of kidney function in NIDDM subjects.

It is currently under debate whether the pathogenesis of end-stage renal failure in non-insulin-dependent diabetes mellitus (NIDDM) is a consequence of microangiopathy alone. The aim of this study was to investigate intrarenal arteriosclerosis and its correlation with kidney function in NIDDM. In 36 diabetic subjects, and in 10 age- and sex-matched healthy control subjects we measured kidney volume and resistive index of the interlobar arteries by duplex Doppler ultrasonography. Clinical and metabolic parameters, renal function and vascular sequelae of the disease were also evaluated. In diabetic subjects resistive index (median 0.72, range 0.54-0.79) was higher than in control subjects (median 0.62, range 0.57-0.66) (2p < 0.002). Kidney volume and resistive index correlated with age (p < 0.004), body mass index (p < 0.001), mean blood pressure (p < 0.001), total and LDL cholesterol (p < 0.01) and creatinine clearance (p < 0.001 and < 0.01, respectively). Kidney volume also correlated with HbA1 (p < 0.01) and resistive index with uric acid (p < 0.01). Lower body macroangiopathy was associated with increased resistive index and reduced kidney volume (2p < 0.05), while upper body macroangiopathy and microangiopathy were not. Our data suggest that macroangiopathy rather than microangiopathy is mainly responsible for impairment of kidney function in NIDDM. The resistive index of interlobar arteries seems to be a reliable marker of intrarenal arteriosclerosis and can be used as a non-invasive, easily available parameter of its evolution.

Arteriosclerosis↗

PubMed1998

Basal synthesis of heat shock protein 70 increases with age in rat kidneys.

The heat shock protein (HSP) system is a mechanism of cell defense induced by stress, constitutively expressed during basal conditions and essential to the maintenance of cellular integrity. Acutely induced HSP synthesis decreases with aging, but the effect of age on the basal expression of HSP70 has not been specifically addressed so far. The aim of this work is to study the age-dependent basal concentrations of HSP70 mRNA in rat kidneys. In 8 young (2-3 months), 6 adult (6-11 months) and 6 old male Wistar rats (22-27 months), steady-state concentrations of HSP70 and gamma-actin mRNA and of rRNA were measured. Pentosidine was measured by HPLC. The basal, unstimulated HSP70 mRNA is increased in young and old rats compared with adult subjects [young: 182% of adult levels (100-299), old: 167% of adults (142-209); p < 0.005]. The amount of pentosidine increases with age (young: 0.6 +/- 0.1; adult: 1.65 +/- 0.15; old: 2.3 +/- 0.3 pmol/mg of protein; p < 0.0001). It seems likely that different mechanisms are responsible for the increased HSP70 basal synthesis in both the young and old animals. The prevalence of anabolic activity can trigger the increased basal production of HSP70 in young rats. The accumulation of posttranslational modified proteins, documented by pentosidine, can chronically enhance HSP70 synthesis in aged animals. The suppression of the synthesis of other proteins accompanying HSP-selective production might contribute to the impairment of specific cell functions in aging.

Actins↗

PubMed1994

Vascular wall von Willebrand factor in human diabetic retinopathy.

PURPOSE: To reconstruct the role played by vascular endothelium in the elevation of circulating von Willebrand factor (vWf) in diabetic patients with microangiopathy and, specifically, to determine whether storage and synthesis of vWf is altered in diabetic retinal vessels. METHODS: Trypsin digests were prepared from retinas obtained post mortem from 11 patients (age 62 +/- 9 years, mean +/- SD) with 9 +/- 5 years of diabetes and 12 nondiabetic control subjects matched for age and sex. Trypsin digests were inspected for the presence of lesions of diabetic retinopathy; vWf protein was localized by indirect immunofluorescence; and vWf mRNA levels were studied by in situ hybridization. RESULTS: vWf immunofluorescence was present in vessels of all sizes. The granular fluorescence was localized to the endothelial cell cytoplasm. Pattern and intensity of staining in diabetic microvessels and large vessels were similar to those observed in the vessels of nondiabetic subjects. The amount of vWf mRNA detected by in situ hybridization in retinal endothelial cells was similar in diabetic (0.92 +/- 0.32 grains/cell) and control (0.91 +/- 0.42 grains/cell) microvessels. Likewise, no differences were observed in vWf mRNA levels in the large vessels of diabetic (0.073 +/- 0.034% grain area) and control (0.069 +/- 0.018 grain area) subjects. CONCLUSIONS: These observations are compatible with the occurrence in diabetes of the slow release of endothelial vWf through the pathway of vWf secretion not linked to synthesis, ie, the regulated pathway.

Adult↗

PubMed1993

Integrin overexpression induced by high glucose and by human diabetes: potential pathway to cell dysfunction in diabetic microangiopathy.

The nature of the process leading to the acellular nonperfused capillaries of diabetic microangiopathy remains unknown. Because these capillaries manifest thickened basement membranes, we asked whether the process causing deposition of excess extracellular matrix in diabetes modifies cell-matrix interactions in a direction that would compromise cell renewal. In 44 individual isolates of human umbilical vein endothelial cells we observed that high glucose concentrations (30 mM) induce coordinate increases in the levels of mRNAs encoding fibronectin and the fibronectin-specific integrin receptor alpha 5 beta 1 as well as in the cognate proteins. Expression of the integrin subunit alpha 3, component of the alpha 3 beta 1 polyspecific receptor for fibronectin, laminin, and collagen, was also up-regulated by high glucose. Overexpression of integrins correlated with increased cell attachment to exogenous fibronectin and laminin as well as to complex matrix. Moreover, cells exhibited firmer steady-state adhesion to their own matrix. To correlate these in vitro observations with events in human diabetic retinopathy we measured integrin levels in retinal trypsin digests prepared from 10 patients with 8.2 +/- 1.6 (mean +/- SE) years of diabetes and 10 age- and sex-matched nondiabetic controls. Microvessels of diabetic patients showed increased immunostaining for beta 1 integrin (P = 0.025) when compared with control microvessels. These data show that high glucose and diabetes increase integrin expression and thus alter the interaction of vascular endothelial cells with their basement membranes in the direction of firmer cell-matrix adhesion. This could compromise the migration and replication critical to the reendothelialization process and contribute to microvascular occlusion.

Cell Adhesion↗

PubMed1992

Comparison of the effects of carvedilol and nifedipine in patients with essential hypertension and non-insulin-dependent diabetes mellitus.

The safety and tolerability of carvedilol, a new antihypertensive agent with the combined pharmacological activities of beta-blockade and vasodilation, and of nifedipine were investigated in patients with essential hypertension and non-insulin-dependent (type II) diabetes mellitus. Twenty patients were openly randomized to receive 25 mg carvedilol once daily (five men and five women; mean age, 63 years) or 10 mg nifedipine t.i.d. (three men and seven women; mean age, 64 years) for a period of 4 weeks. Baseline mean sitting blood pressures were 168/98 and 169/95 mm Hg in the carvedilol and nifedipine groups, respectively. Baseline mean areas under the curve (AUC) of the intravenous glucose tolerance test (IVGTT) for the carvedilol and nifedipine groups were 6,136 +/- 1,195 and 6,287 +/- 1,228 mg/dl/min, respectively. Demographic and efficacy variables were not statistically different between treatment groups. After 4 weeks of therapy, mean sitting blood pressure was significantly (p less than 0.02) reduced to 144/91 mm Hg in the carvedilol group and to 149/87 mm Hg in the nifedipine group. Week 4 IVGTT AUC values of 5,735 +/- 1,464 mg/dl/min in the carvedilol group and 5,988 +/- 993 mg/dl/min in the nifedipine group, representing mean reductions of 6.14% and 3.17%, respectively, were not statistically different from baseline. Both treatments were well tolerated. No patient experienced adverse events in the carvedilol treatment group, whereas two patients in the nifedipine group reported episodes of headache (one patient) and palpitations (one patient); each episode was mild in severity and considered to be related to study medication.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗

PubMed1992

Increased expression of tissue plasminogen activator and its inhibitor and reduced fibrinolytic potential of human endothelial cells cultured in elevated glucose.

In diabetic patients, elevated plasma levels of t-PA and PAI-1 accompany impaired fibrinolysis. To identify mechanisms for these abnormalities, we examined whether vascular endothelial cells exposed to high glucose upregulate t-PA and PAI-1 production and whether ambient PA activity is decreased concomitantly. In 17 cultures of human umbilical vein endothelial cells grown to confluency in 30 mM glucose, the t-PA antigen released to the medium in 24 h was (median) 52 ng/10(6) cells (range 10-384) and the PAI-1 antigen was 872 ng/10(6) cells (range 217-2074)--both greater (P less than 0.02) than the amounts released by paired control cultures grown in 5 mM glucose--29 ng/10(6) cells (range 7.5-216) and 461 ng/10(6) cells (range 230-3215), respectively. In the presence of high glucose, the steady-state levels of t-PA and PAI-1 mRNAs were increased correspondingly (median 142 and 183% of control, respectively, P less than 0.05); high glucose per se and hypertonicity contributed to the upregulation in additive fashion. The PA activity of conditioned medium from cultures exposed to high glucose was 0.4 IU/ml (range 0.2-0.6), which was significantly lower (P less than 0.02) than the PA activity of control medium (0.5 IU/ml, range 0.2-0.9). No difference was observed when comparing the PA activities of acidified conditioned media, expected to be depleted of inhibitors. Thus, high glucose coordinately upregulates endothelial t-PA and PAI-1 expression through effects exerted at the pretranslational level and enhanced by even mild degrees of hypertonicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗

PubMed1991

Malondialdehyde (MDA) level in diabetic subjects. Relationship with blood glucose and glycosylated hemoglobin.

The relationships between plasma malondialdehyde (MDA) and metabolic parameters in type I and II diabetic subjects have been studied at different levels of glycemic control. In 67 diabetics (20 type I, 47 type II, aged 53 +/- 1.2) and 40 healthy subjects (aged 47 +/- 1.75), triglycerides (TG), total cholesterol (CT) and C-HDL, fasting blood glucose (FBG), glycosylated hemoglobin (GHb) and MDA were measured. Diabetic population as a whole showed higher MDA plasma levels compared to controls, together with higher FBG, TG, GHb. MDA showed a significant correlation with both FBG and GHb, but was not correlated to plasma lipids. The patients with a poor metabolic control showed the highest plasma MDA concentrations, significantly different from the group with a better control: GHb less than 10% = MDA 2.77 +/- 0.28 nmol/ml - GHb greater than 10% = MDA 4.22 +/- 0.39 nmol/ml (z = 2.10, a less than 0.02); FBG less than 150 mg/dl = MDA 2.74 +/- 0.32 nmol/ml - FBG greater than 150 mg/dl = MDA 4.15 +/- 0.37 nmol/ml (z = 2.22, a less than 0.02). Glycemic equilibrium seemed to influence plasma MDA, increasing free radical production. This phenomenon probably occurred either because of enhanced glycosylation and platelet aggregation, or impairment of cellular antioxidant protective systems. The increased free radical production may play a role in the pathogenesis of metabolic vasculopathy.

Blood Glucose↗

PubMed1989

Modification of tissue-factor mRNA and protein response to thrombin and interleukin 1 by high glucose in cultured human endothelial cells.

Because diabetic vascular disease is accompanied by a state of hypercoagulability, manifested by increased thrombin activity and foci of intravascular coagulation, we investigated whether a specific procoagulant property of the endothelium--production and surface expression of tissue factor--is modified by elevated glucose concentrations. In unperturbed human vascular endothelial cells, tissue factor mRNA and expression of the functional protein were undetectable and were not induced by 10-12 days of exposure to 30 mM glucose. In thrombin-stimulated cultures, tissue-factor expression was related inversely to cellular density, with confluent cultures producing (per 10(5) cells) half the amount of tissue factor measured in sparse cultures. Cells exposed to high glucose and studied when cell number and thymidine incorporation were identical to control cells manifested increased tissue-factor mRNA level and functional protein production in response to thrombin (P = .002). This effect was not attributable to hypertonicity and was not observed after short exposure to high glucose. In contrast, the tissue-factor response to interleukin 1, a modulator of endothelial function in the context of host defense, was decreased in cells cultured in high glucose (P = .04). These findings indicate that exposure to high glucose can alter tissue-factor gene expression in perturbed vascular endothelium. The reciprocal effects of high glucose on the tissue-factor response to thrombin and interleukin 1 points to different pathways of tissue-factor stimulation by the two agents and suggests functional consequences pertinent to the increased thrombin activity and compromised host-defense mechanisms observed in diabetes.

Cells, Cultured↗

PubMed1988

Platelet and clotting activities after cold stress in diabetic patients.

Platelet and clotting abnormalities have been described in diabetes, but little is known about their relationship to daily stresses. In order to evaluate whether states of abnormal carbohydrate metabolism modify the hemostatic response to stress, 12 subjects with type I diabetes mellitus, 9 with type II, 7 with impaired glucose tolerance and 10 healthy controls were exposed to a cold pressor test. Plasma concentrations of beta-thromboglobulin (index of platelet activation) and of fibrinopeptide A (index of thrombin formation) were measured before and 15 minutes after forearm immersion in melting ice. Basal levels of both proteins were significantly elevated (p less than 0.02) in the combined group of patients with diabetes and impaired glucose tolerance. While in healthy controls cold exposure failed to modify plasma concentration of either protein, obvious changes occurred in the diabetic and impaired glucose tolerance groups. In the combined patients group, beta-thromboglobulin levels decreased from 1.37 +/- 0.44 nmol/l to 1.03 +/- 0.39 (mean +/- SD, p less than 0.01), after the cold test, possibly in consequence of enhanced vascular permeability; while fibrinopeptide A levels increased from 1.52 +/- 1.03 nmol/l to 3.45 +/- 4.19 (p less than 0.02). The degree and pattern of abnormalities observed in basal as well as stimulated levels of fibrinopeptide A differed somewhat among the three groups of patients. These studies indicate that, in the basal state, patients with diabetes or simple carbohydrate intolerance are more susceptible than controls to platelet activation and that after stress thrombin formation can occur although some variability exists among and within groups of patients. The consequences of such increased thrombotic activity may have a bearing on the pathogenesis of large vessel disease, a complication common to diabetes and impaired glucose tolerance.

Blood Coagulation↗

PubMed1988

Increased expression of basement membrane components in human endothelial cells cultured in high glucose.

Although the degree of hyperglycemia is a powerful and independent risk factor for diabetic microvascular disease, it has not been established if and how high glucose per se can induce the typical lesions of microangiopathy. We have investigated in human vascular endothelial cells the expression of messenger RNA (mRNA) for collagen type IV and fibronectin, the two glycoproteins characteristically increased in diabetic basement membranes. In 12 confluent primary cultures exposed for 11 +/- 1 d (mean +/- SD) to 30 mM glucose and exhibiting cell number and thymidine incorporation similar to control cultures, the levels of collagen IV and fibronectin mRNA were, respectively, 238 +/- 140 and 221 +/- 231 percent of control (P less than 0.01). The effects of high glucose were selective (the levels of collagen I and c-myc mRNA remained unchanged), independent of the proliferative activity of the cultures and of the plating substratum, and maintained throughout multiple passages. However, several days of exposure to high glucose were required before their appearance. These observations establish that high glucose is a perturbation sufficient to mimic the effects of diabetes on the regulation of basement membrane components and propose that modifications in gene expression may pertain to the chain of events leading to diabetic angiopathy.

Basement Membrane↗

PubMed1983

[A method for erythrocyte filtration].

Erythrocyte deformability is one of the most important factors on determining blood viscosity. Many microcirculation damages are caused by alteration of viscosity. We propose a method for evaluate erythrocyte filtration using Nucleopore membranes, to study erythrocyte deformability. Normal ranges are calculated in young healthy subjects. Mean filtration time is determined on 5 filtrations for every subject. Filtration rate is expressed by sec/ml and correlated whit haematocrit. The method is not easily utilizable, but it can be useful in the knowledge of the role of the erythrocyte deformability in the altered microcirculation.

Blood Viscosity↗

PubMed1983

[A method for the assay of fibrinopeptide in plasma].

Fibrinopeptide A (FPA) levels have been assayed in 10 normal subjects using a radioimmunoassay (RIA-mat FPA Mallinckrodt). Mean values were 0,97 +/- 0,46 ng/ml. The variation coefficient of the test was 4,82%. The method is well standardized and seems to be useful in the diagnosis of venous thrombosis and in the control of heparin treatment. It seems to be also useful in the evidentiation of an activation af the coagulation system in some diseases (cardiovascular diseases, diabetes etc.)

Fibrinogen↗

PubMed1983