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Biomedical subjects

J Barbosa

Publications and source records attributed to J Barbosa.

At least 91 records · Page 5Linked to original sources
PubMed1990

Long term expansion of cytomegalovirus-specific T cell lines in the absence of antigen or antigen-presenting cells. Use of monosized polystyrene particles coated with agonistic antibodies.

Functional and molecular studies of T lymphocytes involved in normal and abnormal immune responses, i.e., cells infiltrating tissues affected by autoimmune processes, require their previous in vitro expansion. Problems such as unavailability of specific antigen(s) and/or the requirement of large amounts of autologous peripheral blood mononuclear cells (PBMNCs) as feeder cells, demand the development of alternative expansion methods. Cytomegalovirus (CMV)-primed PBMNCs from several seropositive subjects were expanded for 5-6 weeks by stimulation with anti-CD3 coated onto polystyrene beads plus interleukin-2 (IL-2) with a similar efficiency than when the MAb was presented by autologous MNCs. Beads coated with anti-CD4, but not with anti-CD8, were also able to maintain the long term growth of CMV-primed populations of T cells. The expanded T cells of one of these polyclonal populations were cloned by limiting dilution using anti-CD3 or CMV, and autologous PBMNCs as stimuli. 16 and 11 clones, respectively, were obtained and grown to several million cells for 1-2 months by weekly stimulations with anti-CD3-coated beads and IL-2. Proliferation assays performed with most of the clones generated with anti-CD3 stimulation showed that all the tested clones had retained the CMV and the class II MHC restriction specificities for at least 3-4 months after the initial CMV stimulation. All the tested clones secreted IL-2 in response to CMV and were CD3+, CD4+ and CD8-. Comparison of the growth of two of these clones by stimulation with: (a) anti-CD3-coated beads and IL-2; (b) anti-CD3, autologous MNCs and IL-2; or (c) CMV, autologous MNCs and IL-2, showed that the first combination was at least as efficient as the other two in expanding these T cell clones. We conclude that polystyrene monosized particles coated with agonistic antibodies can induce the long term growth of antigen-specific T cell lines in the absence of specific antigen and feeder cells, often unavailable specially in the context of human autoimmune studies.

Antibodies, Monoclonal↗
PubMed1990

Acid-base equilibria of beta-blockers in acetonitrile.

The acid-base equilibria of a series of beta-adrenoceptor blocking drugs in acetonitrile have been studied, and pKHB+ values determined. The theory of such titrations is discussed and simple potentiometric and visual methods in acetonitrile media are proposed for the assay of beta-adrenoceptor blocking drugs.

Acetonitriles↗
PubMed1989

Familial clustering of diabetic kidney disease. Evidence for genetic susceptibility to diabetic nephropathy.

Diabetic nephropathy develops in less than half of all patients with diabetes. To study heredity as a possible risk factor for diabetic kidney disease, we examined the concordance rates for diabetic nephropathy in two sets of families in which both probands and siblings had diabetes mellitus. In one set, the probands (n = 11) had no evidence of diabetic nephropathy, with normal creatinine clearance and a urinary albumin excretion rate below 45 mg per day. In the other set, the probands (n = 26) had undergone kidney transplantation because of diabetic nephropathy. Evidence of nephropathy was found in 2 of the 12 diabetic siblings of the probands without nephropathy (17 percent). Of the 29 diabetic siblings of probands with diabetic nephropathy, 24 (83 percent) had evidence of nephropathy (P less than 0.001), including 12 with end-stage renal disease. No significant differences were noted between the sibling groups with respect to the duration of diabetes, blood pressure, glycemic control, or glycosylated hemoglobin levels. Logistic regression analysis found nephropathy in the proband to be the only factor significantly predictive of the renal status of the diabetic sibling. We conclude that diabetic nephropathy occurs in familial clusters. This is consistent with the hypothesis that heredity helps to determine susceptibility to diabetic nephropathy. However, this study cannot rule out the possible influences of environmental factors shared by siblings.

Adolescent↗
PubMed1989

Genetic analysis of IDDM: the GAW5 multiplex family dataset.

In a collaborative effort by 12 centers from Europe and North America, data were assembled from 94 multiplex families with insulin-dependent diabetes mellitus (IDDM) for analysis of genetic and other factors of possible etiological importance. The dataset contains information on the following genetic markers: HLA-DR beta and -DQ beta restriction fragment length polymorphisms (RFLPs), three RFLPs detected with two probes that map 5' to the insulin gene, the serologically defined HLA loci, and the immunoglobulin allotypes. Data also were included for auto-antibodies to insulin and pancreatic islet cells as possible indicators of pathogenesis and for antibodies to certain viruses that have been implicated as "triggering" agents in IDDM. Medical history of family members was obtained by means of a uniform questionnaire. Identical copies of the dataset were distributed to anyone wishing to participate in the analysis for the IDDM component of GAW5. The multiplex IDDM family dataset is now available on request for further analysis.

Adolescent↗
PubMed1989

Equilibrium constants and assay of benzodiazepines in acetic acid.

The over-all dissociation constants, in anhydrous acetic acid, of a series of benzodiazepines have been determined. A method is described for evaluating the formation constants of the perchlorate salts. From these values simple potentiometric and visual titration methods for the assay of benzodiazepines in acetic acid are described.

Acetates↗
PubMed1989

Long-term study of normal kidneys transplanted into patients with type I diabetes.

We examined the rate of development of the lesions of diabetic nephropathy in transplanted kidneys residing for 6-14 yr in type I (insulin-dependent) diabetic kidney-allograft recipients. Although each recipient had end-stage diabetic nephropathy with his/her own kidneys, there was marked variability in the rate of development of mesangial expansion observed in the transplanted kidneys. The progression of glomerular pathology, including widening of the glomerular basement membrane and expansion of the mesangium, did not correlate significantly with several potential risk factors (e.g., donor source--cadaver or living related, histocompatibility match, age of the recipient or donor, age at onset of diabetes, duration of diabetes before renal failure, immunosuppressive drug dose, blood pressure, and severity of lesions of chronic rejection). However, there was a direct albeit imprecise relationship between the index of mesangial expansion at the final biopsy and the index of glycemic control (r = .61, P less than .01). These observations suggest that currently unknown factor(s) may modulate the progression of diabetic renal disease, even in a population that had uniformly demonstrated nephropathy risk. Our data support the hypothesis that in addition to glycemic control per se, there are risk factors intrinsic to the kidney itself.

Adolescent↗
PubMed1989

Diabetes mellitus type I. The present and the future.

Insulin dependent diabetes is an organ specific immunologic disease caused by pancreatic B cell destruction, mediated by T lymphocytes Present knowledge about insulin dependent diabetes immunogenetics and their relationship with the HLA system is reviewed, highlighting the polymorphism of the D area of that system and its connectors with diabetes. Possible therapeutic interventions in the autoimmune destructive process are discussed.

Autoimmunity↗
PubMed1988

Interaction of CD2 with its ligand, LFA-3, in human T cell proliferation.

Recently, it has been demonstrated that lymphocyte function-associated Ag (LFA-3) is a natural ligand for CD2 and that this receptor-ligand interaction functions in cell-cell adhesion. In this report, we demonstrate that LFA-3 plays a role in T cell activation. L cells were transfected with human genomic DNA and sorted for expression of LFA-3. We demonstrate that LFA-3+ L cells, together with anti-CD3 mAb or with suboptimal doses of PHA, stimulate proliferation of human peripheral blood T cells. Furthermore, thymocyte proliferation was induced by LFA-3+ L cells and suboptimal doses of PHA. Proliferation was inhibited by mAb directed against either CD2 or LFA-3. Stimulation of thymocytes by the combination of PHA and LFA-3+ L cells resulted in the increased expression of the IL-2R, as well as of the surface Ag 4F2, transferrin receptor, and HLA-DR. These data support the conclusion that LFA-3 plays a role in CD2-dependent T cell activation. LFA-3 is widely distributed and is expressed on all APC and target cells. Thus, the ability of the CD2/LFA-3 interaction to costimulate with an anti-CD3 mAb suggests that the CD2/LFA-3 interaction may be involved not only in an Ag-independent alternate pathway of T cell activation but also in Ag-specific T cell activation.

Animals↗
PubMed1988

Genetic relationships between type I and type II diabetes mellitus.

We propose that at least certain subsets of Type I and Type II diabetes share factor(s) responsible for genetic susceptibility. The data presented here to support this contention include: 1. A significantly increased cumulative risk (CR40) to age 40 for Type I diabetes in sibs of probands in families with a Type II diabetic parent (Type II diabetic parent: CR40-24.7 +/- 10.7%; normal parent: CR40 = 7.5 +/- 2.0%, x2 = 12.8, p less than 0.0005). 2. The relative risk (RR) for HLA DR4 in Type I diabetic probands with a Type II diabetic parent is higher than in probands with normal parents (RR = 2.4). 3. The haptoglobin genotype 2-2 is increased in Type I diabetics with Type II parents and the sharing of both HLA and haptoglobin haplotypes in affected sib pairs is distorted with an excess sharing of both haplotypes.

Age Factors↗
PubMed1988

Dissociation constants and assay of weak bases in non-aqueous solvents.

A method is described for evaluating standard cell potentials of specific electrode pair systems in anhydrous acetic acid and acetonitrile. The dissociation constants (K(HB+)) in acetonitrile and the overall dissociation constants (K(B)) and (K(BHClO4)) in anhydrous acetic acid of a series of bases of pharmaceutical interest have been determined. Simple potentiometric and visual titration methods are proposed for the assay of bases and their mixtures.

Journal Article↗
PubMed1988

Diabetes mellitus associated with cystic fibrosis.

The prevalence of overt diabetes mellitus and carbohydrate intolerance was studied in 448 patients with cystic fibrosis (CF). Insulin-dependent diabetes (IDDM) developed in 7.6% of patients (13 male and 21 female). Survival was significantly lower (P less than 0.01) in the IDDM-CF group, with fewer than 25% surviving to age 30 years, whereas nearly 60% of the nondiabetic CF population reached this age. A significant deterioration in CF clinical status, based on NIH score, became apparent 2 years before onset of overt IDDM (P less than 0.05 at 2 years prior, P less than 0.01 at IDDM diagnosis). Total glycosylated hemoglobin (HbA1) was significantly (P less than 0.001) higher for the total CF population (7.3% +/- 1.2%) than for the general non-CF population (6.5% +/- 0.7%), and in the IDDM-CF group (P less than 0.05) compared with normoglycemic CF control patients. Female patients had a higher mean HbA1 after 12 years of age than their male counterparts did (P less than 0.02). HBA1 did not predict the development of IDDM, but there was a weak inverse relationship between HbA1 and both NIH clinical score (r = -0.41, P less than 0.02) and standard pulmonary function tests (forced vital capacity, r = -0.25, P less than 0.01) in the general CF population. Therefore, impaired carbohydrate tolerance in CF is associated with progressive clinical deterioration.

Adolescent↗
PubMed1988

Expression of the T-cell surface molecule CD2 and an epitope-loss CD2 mutant to define the role of lymphocyte function-associated antigen 3 (LFA-3) in T-cell activation.

To define the role of the CD2-lymphocyte function-associated antigen 3 (LFA-3) interaction in T-cell activation, we have expressed a cDNA encoding the human CD2 molecule in a murine antigen-specific T-cell hybridoma. Expression of the CD2 molecule greatly enhances T-cell responsiveness to antigen; this enhancement is inhibited by anti-CD2 and anti-LFA-3 monoclonal antibodies (mAbs). CD2+ hybridomas produce interleukin 2 in response to combinations of anti-CD2 mAbs 9.6 and 9-1 and, in the presence of mAb 9-1, to sheep erythrocytes or to the LFA-3 antigen. Furthermore, hybridomas expressing a mutant CD2 molecule that has lost mAb 9.6 binding do not exhibit the enhanced response to antigen or the ability to respond to LFA-3 plus mAb 9-1, but these hybridomas retain the ability to respond to combinations of anti-CD2 mAbs. The role of the CD2-LFA-3 interaction in T-cell activation and the potential for other physiologic ligands for CD2 are discussed.

Animals↗
PubMed1988

Genetic evidence favouring cytotoxic T cell forbidden clones as the cause of insulin-dependent diabetes mellitus.

Recent evidence indicates that immunoglobulin light chain variable region genes are genetic determinants for Graves' disease, which is caused by autoantibodies which stimulate the thyroid gland. We have tested whether germline immunoglobulin kappa light chain variable region (V kappa) genes contribute to the genetic predisposition for IDDM. Status for the kappa light chain constant region (C kappa) allotype, Km(1), was determined in members of suitable multiplex IDDM families. Such families had two or more siblings with IDDM, together with one parent negative for Km(1) and the other heterozygous, so that each sibling had a 50% chance of receiving the kappa light chain marker. Twenty-one families of this type were found. Of the siblings, disregarding disease status, 31 were concordant with the diabetic proband for Km(1) and 29 were discordant, this close approximation to equality confirming the validity of the methodology. Of the diabetic siblings of the probands, 14 were concordant and 15 discordant. Of the non-diabetic siblings, 17 were concordant and 14 discordant. This similarity shows that V kappa genes, which are closely linked to C kappa genes, are not genetic determinants for IDDM. The contrast with Graves' disease favours the possibility that the islet beta cell destruction of IDDM is mediated by forbidden clones of cytotoxic T cells, rather than of B cells.

Diabetes Mellitus, Type 1↗
PubMed1988

Genetic heterogeneity, modes of inheritance, and risk estimates for a joint study of Caucasians with insulin-dependent diabetes mellitus.

From 11 studies, a total of 1,792 Caucasian probands with insulin-dependent diabetes mellitus (IDDM) are analyzed. Antigen genotype frequencies in patients, transmission from affected parents to affected children, and the relative frequencies of HLA-DR3 and -DR4 homozygous patients all indicate that DR3 predisposes in a "recessive"-like and DR4 in a "dominant"-like or "intermediate" fashion, after allowing for the DR3/DR4 synergistic effect. Removal of DR3 and DR4 reveals an overall protective effect of DR2, predisposing effects of DR1 and DRw8, and a slight protective effect of DR5 and a predisposing effect of DRw6. Analysis of affected-parent-to-affected-child data indicates that a subset of DR2 may predispose. The non-DR3, non-DR4 antigens are not independently associated with DR3 and DR4; the largest effect is a deficiency of DR2, followed by excesses of DR1, DRw8, and DRw6, in DR4 individuals, as compared with DR3 individuals. HLA-B locus distributions on patient haplotypes indicate that only subsets of both DR3 and DR4 are predisposing. The presence or absence of Asp at position 57 of the DQ beta gene, recently implicated in IDDM predisposition, is not by itself sufficient to explain the inheritance of IDDM. At a minimum, the distinguishing features of the DR3-associated and DR4-associated predisposition remain to be identified at the molecular level. Risk estimates for sibs of probands are calculated based on an overall sibling risk of 6%; estimates for those sharing two, one, or zero haplotypes are 12.9%, 4.5%, and 1.8%, respectively. Risk estimates subdivided by the DR type of the proband are also calculated, the highest being 19.2% for sibs sharing two haplotypes with a DR3/DR4 proband.

Adolescent↗