PubMed Health⌕ Search

Biomedical subjects

G A Spinas

Publications and source records attributed to G A Spinas.

At least 19 recordsLinked to original sources
PubMed1995

Nitric oxide (nitrogen monoxide, NO) stimulates insulin secretion by inducing calcium release from mitochondria.

Nitric oxide (nitrogen monoxide, NO) acts as messenger molecule in a variety of cells and may also be involved in the insulin secretory pathway of islet beta-cells. We report here that NO at a low micromolar concentration stimulates epinephrine-sensitive insulin secretion from cells of the beta-cell line, INS-1. Insulin secretion is paralleled by a reversible decrease of the mitochondrial membrane potential and by an increase of the cytosolic calcium. Chelation of intracellular, but not of extracellular calcium prevents the NO-induced insulin secretion. These data indicate that NO can stimulate insulin secretion by deenergizing mitochondria and thereby triggering mitochondrial calcium release.

Animals↗
PubMed1995

[Diabetic nephropathy: significance of microalbuminuria and proteinuria in Type I and Type II diabetes mellitus].

Diabetic nephropathy is a progressive renal disease and represents a serious late complication of diabetes. There are familial clustering and huge ethnic differences in the occurrence of diabetic nephropathy, which point to a genetic predisposition. Diabetic nephropathy is defined by persistent albuminuria (albumin excretion rate [AER] > 300 mg/day), declining glomerular filtration rate and rising blood pressure. Several years of incipient nephropathy, characterized by worsening microalbuminuria (AER 30 to 300 mg/day or 20 to 200 micrograms/min), which is Albustix-negative and detectable by special assays only, are followed by established nephropathy. The natural history of nephropathy differs between insulin-dependent (IDDM) and non-insulin-dependent (NIDDM) diabetes mellitus. In IDDM, nephropathy develops in 30 to 40% of cases. The incidence peaks after 15 to 16 years of diabetes. In NIDDM, estimates of prevalence range from 15 to 20%, and nephropathy often supervenes after a shorter known duration of diabetes than in IDDM. GFR is often increased above normal (hyperfiltration) from the onset of IDDM due to increased renal blood flow, glomerular capillary hypertension and increased filtration surface. The glomeruli are hypertrophied and the kidneys enlarged. In both IDDM and NIDDM, GFR begins to decline irreversibly, when AER has risen to 100 to 300 mg/day at an average rate of 10 ml/min. per year. This is due to progressive reduction of the filtration surface area through mesangial expansion. Serum creatinine levels begin to rise when GFR falls below 50 ml/min, and then end-stage renal failure follows after an average of five years.(ABSTRACT TRUNCATED AT 250 WORDS)

Albuminuria↗
PubMed1995

Cytotoxic T cells specific for glutamic acid decarboxylase in autoimmune diabetes.

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease that results in the destruction of the pancreatic islet beta cells. Glutamic acid decarboxylase (GAD) has been recently indicated as a key autoantigen in the induction of IDDM in nonobese diabetic mice. In human diabetes, the mechanism by which the beta cells are destroyed is still unknown. Here we report the first evidence for the presence of GAD-specific cytotoxic T cells in asymptomatic and recent diabetic patients. GAD65 peptides displaying the human histocompatibility leukocyte antigen (HLA)-A*0201 binding motif have been synthesized. One of these peptides, GAD114-123, binds to HLA-A*0201 molecules in an HLA assembly assay. Peripheral blood mononuclear cells from individuals with preclinical IDDM, recent-onset IDDM, and from healthy controls were stimulated in vitro with the selected peptide in the presence of autologous antigen-presenting cells. In three cases (one preclinical IDDM and two recent-onset IDDM), we detected specific killing of autologous antigen-presenting cells when incubated with GAD114-123 peptide or when infected with a recombinant vaccinia virus expressing GAD65. These patients were the only three carrying the HLA-A*0201 allele among the subjects studied. Our finding suggests that GAD-specific cytotoxic T lymphocytes may play a critical role in the initial events of IDDM.

Adolescent↗
PubMed1995

Differential immunogenetic determinants of polyclonal insulin autoimmune syndrome (Hirata's disease) and monoclonal insulin autoimmune syndrome.

The insulin autoimmune syndrome (IAS), or Hirata's disease, is characterized by the combination of fasting hypoglycemia, high concentration of total serum immunoreactive insulin, and presence of autoantibodies to native human insulin in serum. Autoantibody production is classified as monoclonal or polyclonal, with the majority of IAS cases classified as polyclonal. Previously, we observed a striking association between the human leukocyte antigen (HLA) class II alleles DRB1*0406/DQA1* 0301/DQB1*0302 and Japanese IAS patients with polyclonal insulin autoantibodies (IAAs) and T-cell recognition of human insulin in the context of DRB1*0406 molecules. Because of such a strong HLA association in IAS, we performed intra- and interethnic studies on IAS-associated DRB1 alleles and searched for the critical amino acid residue(s) for IAS pathogenesis. Glutamate at position 74 in the HLA-DR4 beta 1-chain was presumed to be essential to the production of polyclonal IAA in IAS, whereas alanine at the same position of the HLA-DR beta 1-chain might be important in the production of monoclonal IAA.

Adult↗
PubMed1992

[Evaluation of a strip test (Micral test) for the semi-quantitative assessment of microalbuminuria in clinical practice].

Microalbuminuria (AER 20-200 micrograms/min) is the earliest clinical sign of incipient diabetic nephropathy. Current methods for measuring urinary albumin are not suitable for use in an office setting. A test strip (Micral-Test, Boehringer Mannheim [D]) based on immunochemical principles has recently been developed which allows semiquantitative detection of urinary albumin concentrations. In this study Micral-Test results were compared with conventional immunoturbidimetric laboratory measurement. 65 single-void urine samples of diabetic patients were analyzed (38 type 1, 27 type 2). Urinary albumin values as obtained from Micral-Test and laboratory measurement showed a significant correlation (r = 0.85, p less than 0.001). An interclass correlation was performed for normal urinary albumin values (less than 20 micrograms/ml) and for microalbuminuric values (20-200 micrograms/ml) and resulted in correlation coefficients of 0.56 and 0.81 respectively. Interindividual variation was checked by three observers reading the same 13 urine samples. The values obtained from the three observers correlated significantly (r greater than 0.95, p less than 0.001). The test strip must be evaluated after precisely 5 minutes in order to avoid false pathological results. In conclusion, the Micral-Test is a good screening method for easy and quick detection of microalbuminuria in an office setting.

Adult↗
PubMed1992

Non-invasive assessment of gastrointestinal motility disorders in diabetic patients with and without cardiovascular signs of autonomic neuropathy.

Twenty six patients with insulin dependent diabetes mellitus underwent a gastric emptying test, a gall bladder contraction test, an orocaecal transit study, and a colon transit test. Eleven patients had signs of cardiovascular autonomic neuropathy, 15 patients were without signs of cardiovascular autonomic neuropathy. Mean gastric clearance of radioopaque markers ingested with a meal averaged 29.5 (2.3) markers per six hours in subjects without cardiovascular autonomic neuropathy compared with 17.8 (2.3) markers per six hours in patients with cardiovascular autonomic neuropathy (p < 0.02). Gall bladder emptying in response to graded CCK8 stimulation was impaired in five of 11 patients with cardiovascular autonomic neuropathy, whereas it was normal in the patients without cardiovascular autonomic neuropathy (p < 0.01). Oral caecal transit times were not significantly different in the two patient groups, whereas colonic transit was slower in the patients with cardiovascular autonomic neuropathy compared with the group without cardiovascular autonomic neuropathy (p < 0.02). There was no correlation between disturbed gastric clearance, impaired gall bladder contraction, and prolonged colonic transit time in the patients with cardiovascular autonomic neuropathy nor was there a correlation between any disturbed motor function and age or duration of diabetes. It is concluded that autonomic neuropathy can affect motor functions throughout the gastro-intestinal tract. Any disturbed motor function in the gut could therefore be one of the numerous expressions of diabetic neuropathy affecting the cardiovascular, the endocrine or the gastrointestinal system.

Adult↗
PubMed1992

Gold-specific T cells in rheumatoid arthritis patients treated with gold.

Gold-specific T lymphocyte clones were isolated from a patient with rheumatoid arthritis who developed delayed type hypersensitivity reactions to gold. All of the isolated T cell clones required histocompatible antigen presenting cells as well as gold for induction of proliferation. Using a panel of HLA-homozygous Epstein Barr virus-transformed B (EBV-B) cells and anti-HLA antibodies, the clones were shown to recognize gold in the context of DR1 molecules. Gold recognition did not require active antigen processing since specific proliferation was not affected by glutaraldehyde fixation of the DR1 homozygous antigen presenting cells. Furthermore, we could show that gold salts inhibited peptide-induced responses of a peptide-specific T cell clone. In addition to providing evidence for gold-specific T cells in gold-treated RA patients exhibiting delayed type hypersensitivity responses, these data suggest that gold can alter MHC-peptide complexes. The latter observation may in part explain the mechanism/s responsible for both the therapeutic and the toxic effects of gold.

Antigen-Presenting Cells↗
PubMed1992

Release of soluble receptors for tumor necrosis factor (TNF) in relation to circulating TNF during experimental endotoxinemia.

Serial plasma samples from human volunteers obtained after intravenous administration of Escherichia coli endotoxin were analyzed for the presence of circulating soluble tumor necrosis factor receptors (sTNFR). A four- to fivefold increase of type A (p75) and type B (p55) sTNFR was observed 3 h after endotoxin challenge. Pretreatment of the volunteers with ibuprofen before the injection of endotoxin resulted in a slight increase (3.87 +/- 0.2 vs. 3.27 +/- 0.3 ng/ml) and temporal shift of sTNFR-A release concurrent to a marked augmentation of TNF levels (603 +/- 118 vs. 338 +/- 56 pg/ml) as compared to the group without ibuprofen pretreatment. There was a significant correlation between peak sTNFR-A levels and peak TNF levels in the individual probands (r = 0.52, P = 0.04). On the contrary, release kinetics and plasma concentrations of sTNFR-B were identical in both groups (7.38 +/- 0.69 vs. 7.44 +/- 0.33 ng/ml) and no correlation with individual TNF levels was observed. The amount of sTNFR liberated upon endotoxin challenge was not sufficient to block TNF-mediated cytotoxic effects. Our data indicate that the release in vivo of type A and type B sTNFR upon a short exposure to endotoxin is regulated differently.

Adult↗
PubMed1992

Elevated proinsulin levels related to islet cell antibodies in first-degree relatives of IDDM patients.

OBJECTIVE: To assess whether proinsulin levels are elevated in first-degree relatives of insulin-dependent diabetes mellitus (IDDM) patients and whether there is a relationship between proinsulin levels and the occurrence of immunological markers. RESEARCH DESIGN AND METHODS: Fasting proinsulin concentrations were measured in 85 first-degree relatives (54 siblings, 20 parents, 11 children) of IDDM patients and in 90 age- and weight-matched control subjects with no family history of diabetes mellitus. RESULTS: Fasting proinsulin levels (median, 25th, and 75th percentiles) were 8 pM (range 3.2-14 pM) in first-degree relatives and 1.7 pM (range 1.7-4 pM) in control subjects (P less than 0.0001). Proinsulin was significantly elevated in siblings (7.2 pM, range 3.8-15 pM; P less than 0.0001), parents (9.8 pM, range 6.4-13 pM; P less than 0.0001), and children (6.6 pM, range 1.8-12 pM, P = 0.04) compared with control subjects but without differences between these groups. Islet cell antibody positive (ICA+) IDDM relatives had significantly higher proinsulin levels than ICA- (16 pM; range 7.2-25 vs. 6.9 pM, range 3.1-12 pM; P = 0.02). There was no difference between individuals with and without insulin autoantibodies. No difference in proinsulin levels was observed if the relatives were subdivided according to HLA-DR sharing with the diabetic proband. CONCLUSIONS: Fasting proinsulin concentrations were raised not only in siblings but also in parents and children of IDDM patients. Because proinsulin is more elevated in ICA+ than in ICA- subjects, increased proinsulin levels could reflect minor beta-cell damage due to previous immunological attack.

Adult↗
PubMed1991

[The practical assessment of micro-albuminuria as a marker for beginning diabetic nephropathy in: which urine sampling method?].

Microalbuminuria, i.e. elevated urinary albumin excretion rate between 20 and 200 micrograms/min, is a strong predictor of subsequent overt diabetic nephropathy. Screening for microalbuminuria is essential, since it has been shown that development of overt nephropathy can be delayed or even prevented by therapeutic measures such as strict metabolic control, early aggressive antihypertensive treatment, or restriction of protein intake. Several urine collection methods for the measurement of microalbuminuria have been proposed. In a prospective study with 40 diabetic outpatients we have compared albumin excretion in urine collected over 24 h, during a timed overnight period, and in a spot urine sample collected at random while the patient attended the outpatient clinic. In addition, the reproducibility of the three urine collection methods was assessed. For this purpose, each patient underwent 3 consecutive collections at an interval of at least 4 weeks. Our data indicate that calculation of an albumin/creatinine quotient in a spot urine probe is a reliable screening test for microalbuminuria. If this quotient is increased (greater than 2), timed overnight collection should be performed.

Adolescent↗
PubMed1991

High frequency of human immunodeficiency virus-associated autonomic neuropathy and more severe involvement in advanced stages of human immunodeficiency virus disease.

We conducted a controlled trial to determine frequency and severity of autonomic neuropathy in patients infected with the human immunodeficiency virus (HIV). We studied 25 HIV-seropositive patients and 10 seronegative controls in HIV risk groups by means of five cardiovascular tests, and autonomic neuropathy was graded with a scoring system. The overall autonomic test score differed between patients and controls and was higher in patients with advanced (Centers for Disease Control class IV) disease than in those with earlier (class II or III) HIV disease. Of the patients, 60% had findings of autonomic dysfunction. Our data demonstrate a high prevalence of autonomic neuropathy in HIV-infected patients. Advanced HIV disease is associated with more severe involvement than earlier disease states.

Adult↗
PubMed1991

Pretreatment with ibuprofen augments circulating tumor necrosis factor-alpha, interleukin-6, and elastase during acute endotoxinemia.

Plasma levels of tumor necrosis factor-alpha (TNF alpha), interleukin-1 (IL-1), and interleukin-6 (IL-6) were monitored after intravenous administration of Escherichia coli endotoxin with or without ibuprofen pretreatment to healthy volunteers. Intravenous endotoxin (n = 7) resulted in elevated plasma TNF alpha concentrations with maximal levels at 90 min (369 +/- 44 pg/ml, P less than .001 vs. saline controls, n = 7). The rise in TNF-alpha was followed by a rise in plasma IL-6 (27 +/- 12.8 ng/ml), peaking 30-90 min thereafter. Pretreatment with ibuprofen (n = 6) caused a significant augmentation and temporal shift in cytokine elaboration with maximal TNF alpha levels (627 +/- 136 pg/ml) at 120 min and IL-6 peaks (113 +/- 66 ng/ml) at 180 min. In ibuprofen-treated volunteers, the additional increase in TNF alpha was paralleled by increased levels of circulating elastase. In vitro experiments suggest a causal relationship between these events. Thus, the cyclooxygenase inhibitor ibuprofen blunts the clinical response to endotoxin but augments circulating cytokine levels and leukocyte degranulation.

Adult↗
PubMed1991

Repetitive exposure of pancreatic islets to interleukin-1 beta. An in vitro model of pre-diabetes?

The slowly progressing loss of glucose tolerance over years before clinical onset of Type 1 (insulin-dependent) diabetes mellitus may be due to repetitive immunological attacks on the pancreatic beta-cell mass. Accordingly, we studied the effects of repetitive exposure of isolated rat pancreatic islets to the beta-cytotoxic immune-mediator interleukin-1 beta. Islets were exposed thrice to 60 U/ml of recombinant interleukin-1 beta for 24 hr. The islets were allowed to recover for 6 d between the interleukin-1 beta exposure periods. After each of the three interleukin-1 beta exposure periods, islet capacity to release insulin was decreased to 12, 6 and 3% of control, respectively, and islet insulin content decreased to 75, 56 and 21%, respectively. After the two recovery culture periods, the capacity for insulin release reversed to 75 and 30% of control, respectively. An increase in islet insulin content was only seen after the first recovery culture. During repetitive as well as long-term (6 d) interleukin-1 beta exposure of islets, medium accumulation of glucagon was either increased or unaffected. In analogy, beta-cells exposed to interleukin-1 beta for 6 d showed ultrastructural signs of degeneration and cytolysis, whereas alpha-cells were intact. In conclusion, interleukin-1 beta injury to beta-cells was partially reversible, but successive episodes of islet interleukin-1 beta exposure were increasingly detrimental; alpha-cell function and structure did not show susceptibility to damage by interleukin-1 beta. These findings may contribute to our understanding of islet cell behaviour before and during onset of Type 1 diabetes.

Animals↗
PubMed1991

[Adrenal cortex and gonadal function in HIV infected patients].

Several studies have demonstrated diminished gonadal or adrenal function in patients infected with the human immunodeficiency virus (HIV). We have evaluated gonadal and adrenal function in 18 unselected ambulatory patients seropositive for HIV and clinically categorized as asymptomatic (n = 6), AIDS-related complex (ARC, n = 8) or acquired immunodeficiency syndrome (AIDS, n = 4). None of the patients was critically ill at the time of the hormone studies. Adrenal function was assessed using the 30 minute ACTH-test, and gonadal function by determination of the free testosterone serum level, both simple screening tests easily performable in practice. All male patients had normal free testosterone serum levels. In 5 (29%) of 17 patients (one asymptomatic, 3 with ARC, and 1 with AIDS) serum cortisol concentrations responded subnormally to synthetic ACTH, suggesting diminished adrenal cortisol reserve. The etiological role of the cytomegalovirus (CMV), which is said to be the most frequent cause of adrenal insufficiency in these patients, was unclear in our patients, because 4 of the 5 cases with the subnormal as well as 11 of the 12 with the normal test had antibodies against CMV in serum.

Adrenal Cortex↗