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Biomedical subjects

R Roy

Publications and source records attributed to R Roy.

At least 343 records · Page 19Linked to original sources
PubMed1987

Involvement of prostaglandin A1 in interrupting early pregnancy in Syrian golden hamsters.

The effects of a single administration of authentic prostaglandin A1 intravaginally in early pregnant hamsters were investigated. A single dose of 1 mcg/animal given on day 4 of pregnancy inhibited the appearance of embryonic swellings when observed on day 8 of pregnancy. A significant fall (p less than 0.01) in FSH with a rise (p less than 0.03) in prolactin concentration in the serum and no change in LH levels were observed. The pituitary content of prolactin showed a significant decrease (p less than 0.0006) with no change in FSH and LH contents. Progesterone concentration in the serum was markedly reduced (p less than 0.002), along with that of the ovaries (p less than 0.01). The decline in progesterone concentration coincided with the absence of corpora lutea and the embryos. However, no change in ovarian weights was observed. These results indicate the contragestive potential of prostaglandin A1. It appears to act as a luteolytic agent by disrupting the luteotropic complex (FSH:prolactin ratio).

Animals↗
PubMed1987

Low kidney graft survival in Lewis negative patients after regrafting and newer matching schemes for Lewis.

Le-cadaver donor kidney transplant recipients regrafted had a 1-year graft survival rate of 0%. This was statistically significantly lower than survival rates in Lea or Leb patients of 60% and 64%, respectively, at 1 year (P = .01 and P = .009). We conclude that if Le- patients had rejected an Le+ graft, a repeated incompatibility should be avoided since the recipients had already demonstrated immunoreactivity against this epitope. Recipients being confronted with an Le group mismatch in the first graft often have successful grafts and the difference in 1-year graft survival of Lea (75%), Leb (76%), and Le- (68%) patients was not statistically significant different. We suggest that the matching scheme for the Le groups be reevaluated. The older method of matching on the basis of Le+ and Le- is probably no longer justified. According to chemical structure, it would appear that Leb should be a universal recipient and Lec a universal donor. This scheme, however, has failed to correspond to interracial transplants between whites and blacks. A matching scheme that requires identity between donor and recipient showed a remarkable correlation with the results between black-to-black, black-to-white, white-to-black and white-to-white transplants.

Blood Group Incompatibility↗
PubMed1986

Induction of meningococcal group B polysaccharide-specific IgG antibodies in mice by using an N-propionylated B polysaccharide-tetanus toxoid conjugate vaccine.

Conjugation of the group B meningococcal polysaccharide to tetanus toxoid failed to substantially enhance its immunogenicity in mice. Therefore, additional chemical manipulation of the basic structure of the group B meningococcal polysaccharide was attempted, on the premise that a synthetically derived artificial antigen might be capable of modulating the immune response in mice to produce elevated levels of cross-reactive group B meningococcal polysaccharide-specific antibodies. To achieve this, the antigenicity of the modified polysaccharide to group B meningococcal polysaccharide-specific antibodies had to be preserved, and this criterion could only be satisfied in modifications in which the carboxylate and N-carbonyl groups of the sialic acid residues of polysaccharide remained intact. Therefore, the most successful modifications were accomplished by N-deacetylation of the group B meningococcal polysaccharide with strong base to yield a precursor that could then be N-acetylated or N-arylated with different substituents. For example, the introduction of N-propionyl groups, followed by conjugation of the resultant N-propionylated group B meningococcal polysaccharide to tetanus toxoid, yielded an antigen that when injected in mice induced in them high levels of cross-reactive group B meningococcal polysaccharide-specific IgG antibodies. The T cell dependency of this antigen was established when it was demonstrated that the levels of these B polysaccharide-specific antibodies could be significantly boosted by using both the N-propionylated- and native N-acetylated-group B meningococcal polysaccharide-tetanus toxoid conjugates.

Animals↗
PubMed1986

HLA-A,B and DR matching in corneal transplantation.

One hundred eighty-five consecutive corneal transplants were performed in recipients selected on the basis of the best available HLA-A,B and DR match. Endothelial rejection-free transplant survival in this group was compared to a retrospective historical control group of 199 consecutive transplants performed in recipients selected on the basis of age and longest wait criteria. The two groups were comparable with regards to primary diagnosis, preoperative corneal vascularization, donor and recipient age, and operative techniques. Thirty-eight transplants in the study group and 28 transplants in the control group were at high risk for endothelial transplant rejection. At 12 months, the estimated rejection-free survival (Kaplan-Meier method) of the high-risk study group transplants was 87% compared to 74% for the high-risk historical control group and transplants. This difference did not reach the significant level of 0.05 with the log-rank test. The 12-month estimated rejection-free survival of low-risk study group and historical control group transplants were similar. In the study group, the 12-month estimated rejection-free survival of well-matched transplants was 95% compared to 83% for poorly matched transplants (log rank, P less than 0.02). These findings suggest that a relationship exists between HLA-A,B and DR compatibility of donor and recipient and the corneal rejection-free transplant survival.

Corneal Transplantation↗
PubMed1986

Improved renal allograft function and survival following nonspecific blood transfusions. I. Induction of soluble suppressor factors inhibiting the mitogenic response.

A small number of blood transfusions (1-3) seems sufficient to improve the cadaveric renal allograft outcome, probably via induction of some nonspecific suppressive activity. This activity was assessed by the concanavalin A (Con A) enhancement method; when present, the response of freshly isolated patients' cells to a submitogenic dose of Con A was lowered, leading to a Con A ratio greater than 5, significantly (P less than 0.0001) higher than the one observed in normal controls or untransfused uremic patients. The correlation between this suppressive activity and graft outcome was determined. Thirty-five patients were studied over a 12-month period for graft function (creatinine level) and survival. Both parameters were significantly improved in the group of patients whose Con A ratio was greater than 5 after transfusions. A soluble suppressor factor, or factors, released into the supernatant of patients' lymphocytes cultured for 48 hr, seems responsible for this suppressive activity. Moreover this process is nonspecific, since it suppresses mitogenic response of cells isolated from normal untransfused volunteers, and could be observed when peripheral blood mononuclear cells were used, but not with purified adherent or nonadherent cells. Addition of indomethacin to the cells during the elaboration of the supernatant abolished this activity. However, amounts of PGE2 secreted into the supernatant during the 48 hr of culture could not be correlated with this suppressive activity. These findings suggest that induction of nonspecific immunosuppression by a few blood transfusions could predict a better kidney graft outcome.

Adult↗
PubMed1986

A psychosocial perspective on chronic pain and depression in the elderly.

Chronic pain and depression often coexist in elderly individuals. This paper explores, from a clinical perspective, the antecedents for depressive symptoms in older chronic pain patients. A case is made for active social work intervention with elderly patients who manifest this complex syndrome of chronic pain.

Aged↗
PubMed1986

Characteristics of two types of meningococcal group C polysaccharide conjugates using tetanus toxoid as carrier protein.

Effective meningococcal vaccines have to induce protection against groups A, B, C, W-135 and Y meningocci. Polysaccharides are the most effective vaccine candidates against groups A, C, W-135 and Y meningococci. The vaccine potential of polysaccharides is enhanced by conjugating the polysaccharides to carrier proteins. This paper describes the preparation and immunological characterization of two types of group C polysaccharide - tetanus toxoid conjugate. Both types of conjugate were produced by different procedures. Procedure i. depends on cross-linking of both components with N-ethyl-N'-(3-dimethylaminopropyl) carbodimide. Procedure ii. is a more monofunctional way of conjugating partially depolymerized polysaccharide with tetanus toxoid by reductive amination. The antigenic activity of the tetanus toxoid component of the conjugates containing this carrier protein was studied in ELISA and showed differences between the conjugate preparations. The immunogenic activity of all conjugate preparations was tested in mice. All conjugates produced IgG antibodies to the polysaccharide component, although the booster effects of procedure ii. conjugates were less pronounced than those of procedure i. conjugates. The immunogenic activity of the tetanus toxoid component of the various conjugate preparations correlated rather well with their antigenic activities as measured in ELISA.

Animals↗
PubMed1985

Structural determination of the capsular polysaccharide of Neisseria meningitidis group I: a two-dimensional NMR analysis.

The capsular polysaccharide antigen of Neisseria meningitidis group I was isolated by Cetavlon precipitation and purified by ion-exchange chromatography. The structure of the I polysaccharide was determined largely by comprehensive proton and carbon-13 nuclear magnetic resonance studies in which both one-dimensional and two-dimensional experiments were carried out directly on the I polysaccharide. The I polysaccharide is composed of the repeating unit----4)alpha-L-GulpNAcA(1----3)[4-OAc]beta-D-ManpNA-cA(-- --in which the former residue adopts the 4C1 (L) conformation and the latter residue adopts the 4C1 (D) conformation. The one-bond coupling between the anomeric carbon and proton (1J13C,H) of the 2-acetamido-2-deoxy-beta-D-mannuronopyranosyl residue is not consistent with its beta-D configuration. This anomalous value of 1J13C,H for this residue is due to through-space anisotropy effects on its anomeric proton, generated by the proximity of the carboxyl group of the neighboring 2-acetamido-2-deoxy-alpha-L-guluronopyranosyl residue. The O-acetyl substituents of the I polysaccharide are essential for its antigenicity to group I polysaccharide-specific antibodies.

Carbohydrate Conformation↗
PubMed1985

Protein synthesis in rabbit reticulocytes. Purification and properties of an Mr 80,000 polypeptide (Co-eIF-2A80) with Co-eIF-2A activity.

The high molecular weight protein complex, Co-eIF-2, contains both Co-eIF-2A and Co-eIF-2C activities (Bagchi, M. K., Banerjee, A. C., Roy, R., Chakravarty, I., and Gupta, N. K. (1982) Nucleic Acids Res. 10, 6501-6510). Co-eIF-2A stimulated Met-tRNAf binding to eukaryotic initiation factor-2 (eIF-2) both in the presence and absence of Mg2+. Co-eIF-2C stimulates Met-tRNAf binding to eIF-2 in the presence of Mg2+ by relieving Mg2+ inhibition of ternary complex formation from eIF-2. Co-eIF-2 protein complex contains several polypeptides including Mr 80,000 and 50,000 polypeptides. Three polypeptides (Mr 80,000, 50,000 and 25,000) are present in 0.5 M KCl ribosomal salt wash and each possesses Co-eIF-2A activity. Mr 80,000 polypeptide (Co-eIF-2A80) has been purified to homogeneity and its properties studied. 1) Co-eIF-2A80 stimulated Met-tRNAf binding to eIF-2 and the complex formed was resistant to aurintricarboxylic acid. 2) Co-eIF-2A80 activity was N-ethylmaleimide-resistant and heat-labile; it was destroyed by heating at 55 degrees C for 4 min. 3) Antibodies prepared against homogeneous Co-eIF-2A80 strongly inhibited protein synthesis in reticulocyte lysates and, also, eIF-2 and Co-eIF-2 promoted Met-tRNAf binding to 40 S ribosomes. Inhibition of protein synthesis in reticulocyte lysates was overcome by preincubation of anti-Co-eIF-2A80 with homogeneous Co-eIF-2A80 and was partially overcome by similar preincubation with Co-eIF-2. 4) Upon limited digestion with Staphylococcus aureus V8 protease, the homogeneous Co-eIF-2A80 gave two major polypeptide fragments (Mr 50,000 and 25,000). Upon similar treatment, an Mr 80,000 polypeptide band isolated from the sodium dodecyl sulfate-gel of the Co-eIF-2 protein complex gave four major polypeptide fragments, and two of these fragments (Mr 50,000 and 25,000) were similar to those given by Co-eIF-2A80, indicating that this Mr 80,000 polypeptide band contains the Co-eIF-2A80 component. We suggest that Co-eIF-2A80 is a component of Co-eIF-2 and is also essential for Co-eIF-2 activity and overall peptide chain initiation.

Animals↗
PubMed1985

Xanthine oxidase as a source of free radical damage in myocardial ischemia.

Experiments were performed to determine if xanthine oxidase is a source of free radicals during myocardial ischemia. Open chest dogs were subjected to 1 h of total occlusion of the left anterior descending coronary artery followed by 4 h of reperfusion. Directly after coronary artery occlusion, Ce141 microspheres were injected into the left atrium to mark the ischemic bed. At the end of reperfusion, the hearts were removed and sectioned. Autoradiography determined the ischemic myocardium at risk, and the necrotic zone was determined by triphenyl-tetrazolium staining. Animals were divided into three groups: control, allopurinol (24-h oral pretreatment 400 mg, then 50 mg/kg IV bolus on occlusion); and superoxide dismutase starting with occlusion (15 000 U/kg). The size of the infarct as a percentage of the tissue at risk was: 23.1 +/- 4.1 for the control; 8.7 +/- 1.2 for the allopurinol group; and 5.4 +/- 1.2 for the superoxide dismutase group. The infarcts in the allopurinol and superoxide dismutase groups were significantly smaller than those in the control groups. In a second series of experiments we determined the xanthine oxidase/xanthine dehydrogenase content of dog myocardium. The left anterior descending branch was ligated for 30 min and then biopsies were removed from both the normal and the ischemic regions. Total enzyme content did not differ between the two regions averaging 0.259 U/g protein for the ischemic tissue and 0.225 U/g protein for the normal region. Only 9.8% of the enzyme was in the oxidase form in the normal region while 32.8% was in the oxidase form in the ischemic zone.(ABSTRACT TRUNCATED AT 250 WORDS)

Allopurinol↗