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Biomedical subjects

A Mathew

Publications and source records attributed to A Mathew.

At least 73 records · Page 4Linked to original sources
PubMed1993

Screening for nasopharyngeal carcinoma with an ELISA using the Epstein-Barr virus nuclear antigen, EBNA 1: a complementary test to the IgA/VCA immunofluorescence assay.

An ELISA using the Epstein-Barr virus nuclear antigen 1 (EBNA 1) was found to detect selectively specific IgA in sera from patients with nasopharyngeal carcinoma (NPC). The antigen, p107, was a 20-amino acid synthetic peptide, representing a major epitope of EBNA 1.267/294 (90.8%) of NPC patients had IgA antibodies to p107 but in normal individuals, only 41/577 (7.1%) had IgA/p107. In sera from patients with other cancers, 11/77 (14.3%) had IgA/p107 reactivity. 124 IgA/VCA positive and 86 IgA/VCA negative NPC sera were also tested for IgA/p107 binding in ELISA. The majority of IgA/VCA positive sera (117) also contained IgA/p107 antibodies. Of interest was the detection of 74/86 IgA/p107 reactive sera in the IgA/VCA negative group. The results suggest that the IgA/p107 ELISA could become a useful, complementary screening assay to the IgA/VCA immunofluorescence test for detection of NPC.

Amino Acid Sequence↗
PubMed1992

Independent predictors of response and disease-free survival in oral cancer treated with radical radiation therapy.

There have been no reports concerning the independent predictors of response and disease-free survival (DFS) in oral cancer in India, where the highest incidence is reported. The authors analyzed the outcome of radical radiation therapy of 378 patients with oral cancer and found that the complete response rate within 6 months of completion of treatment was 45% and the 5-year DFS was 34% (95% confidence interval 29% to 39%). Regional lymph node involvement (P less than 0.001), histologic type (P less than 0.01), and the intraoral site of lesion (P less than 0.025) were identified as independent predictors of response when adjusted in a forward stepwise logistic regression analysis. The Cox proportional hazards regression analysis revealed that regional lymph node involvement (P less than 0.001) and histologic type (P less than 0.05) were independent prognostic factors for DFS. Patients with fixed regional lymph node involvement demonstrated a relative risk (RR) of 2.4 compared with those with N0 disease. Patients with well-differentiated squamous carcinoma had an RR of 2, and those with other histologic types (other than verrucous carcinoma) had an RR of 1.5.

Adult↗
PubMed1992

Neisseria sicca endocarditis with embolic phenomena.

Two patients with poor oral hygiene developed Neisseria sicca endocarditis, one after probable intravenous drug abuse and Staphylococcus aureus endocarditis and the other after a periodontal surgical procedure. Both experienced significant embolic phenomena and both required 6 or more weeks of intravenous antibiotic therapy. The diagnosis of N. sicca endocarditis must be considered when this organism is isolated from blood cultures in patients with emboli.

Adult↗
PubMed1991

Exosome formation during maturation of mammalian and avian reticulocytes: evidence that exosome release is a major route for externalization of obsolete membrane proteins.

We have assessed whether exosome formation is a significant route for loss of plasma membrane functions during sheep reticulocyte maturation in vitro. Although the recovery of transferrin binding activity in exosomes is at best approximately 25-30% of the lost activity, recoveries of over 50% of the lost receptor can be obtained if 125I-labelled transferrin receptor is measured using an that receptor instability may contribute to the less than quantitative recovery of the transferrin receptor. Significantly higher (75-80%) levels of the nucleoside transporter can be recovered in exosomes during red cell maturation using 3H-nitrobenzylthioinosine binding to measure the nucleoside transporter. These data suggest that exosome formation is a major route for removal of plasma membrane proteins during reticulocyte maturation and plasma membrane remodelling. We have also shown that both in vivo and in vitro, embryonic chicken reticulocytes form exosomes which contain the transferrin receptor. Thus, exosome formation is not restricted to mammalian red cells, but also occurs in red cells, which retain organelles, such as nuclei and mitochondria, into the mature red cell stage.

Animals↗
PubMed1991

Comparison of hemin enhancement of burst-forming units-erythroid clonal efficiency by progenitor cells from normal and HIV-infected patients.

The ability of peripheral-blood hematopoietic progenitor cells from AIDS patients and normal controls to respond to erythropoietin (Epo) was assessed for burst-forming units-erythroid (BFU-E). BFU-E colony formation from AIDS patients' peripheral blood responded to a wide range of Epo concentrations (0.5-4 U) in a similar manner as erythroid progenitors obtained from normal peripheral blood. The optimum dose response of BFU-E to Epo was 2 U which resulted in generation of 71 +/- 4 BFU-E in AIDS patients (n = 10), as compared to 77 +/- 5 BFU-E in normal donors (n = 3). The optimum concentration range of hemin enhancement of erythroid progenitor BFU-E was 10-50 microM. In all instances, Epo was essential for BFU-E growth. Inclusion of hemin at a concentration of 10 microM in AIDS patients' peripheral-blood erythroid progenitor cells resulted in enhancement of BFU-E by 136-215%. Similarly, inclusion of hemin (10-100 microM) in normal bone marrow erythroid progenitor cell cultures resulted in enhancement of BFU-E. Inclusion of an equivalent amount of iron or tin protoporphyrin to progenitors cells from AIDS patients' peripheral blood had no effect on the number of colonies observed. On the other hand, inclusion of another heme analogue, zinc protoporphyrin, in AIDS or normal cultures resulted in a 50% suppression of BFU-E colony formation. These results demonstrate that peripheral-blood mononuclear cells from AIDS patients retain the capacity to generate erythroid precursors such as BFU-E in the presence of Epo, and that hemin has a specific enhancement effect on growth of BFU-E colony formation obtained from peripheral blood or bone marrow cells.

AIDS-Related Complex↗
PubMed1991

Pneumothorax: an unusual presentation of primary bronchogenic neoplasm.

We report the occurrence of spontaneous pneumothorax as the initial pulmonary event in a patient subsequently found to have a primary adenocarcinoma of the ipsilateral lung. A review of the literature regarding this rare presenting feature of bronchogenic neoplasm is provided.

Adenocarcinoma↗
PubMed1990

Role of heme metabolism in AZT-induced bone marrow toxicity.

We studied the effects of azidothymidine (AZT) on rat bone marrow heme metabolism and colony growth as determined by assays of granulocyte-macrophage (CFU-GM), erythroid (CFU-E), burst-forming erythroid (BFU-E), and alpha-aminolevulinic acid synthase (ALAS), the first enzyme in the heme pathway. In all cases, AZT (1-0.01 microM) was found to be toxic to bone marrow colony growth. When AZT was included in colony assays, 1 microM resulted in 98-100% inhibition, whereas lower concentrations (0.01 microM) inhibited growth by 58-76%. In addition, cultures from AZT-treated animals had a marked reduction in colony growth as compared with sham controls. In most cases, hemin (10(-5) M) was found to overcome some of the colony inhibitory effects of AZT. Analysis of heme metabolism indicated that ALAS activity was reduced by 71% in bone marrow cells from treated animals. ALAS activity for control was 204 +/- 33 pM ALA formed/4 X 10(6) cells/hr, whereas ALAS activity from AZT-treated animals was only 60 +/- 3 pM ALA formed/4 x 10(6) cells/hr. It is considered that AZT toxicity may be due to a depression in the pool of available heme, which is required for adequate hematopoiesis.

5-Aminolevulinate Synthetase↗
PubMed1990

The control of reaching movements by young infants.

Samples of reaches were obtained from groups of infants aged 4.5, 6, and 7.5 months. Split-screen video recordings were transcribed as sequences of (x,y,z) hand coordinates, and the hand path was examined for evidence of initial aiming and subsequent correction of the movement path. At all ages, the initial direction of the movement was correlated with target direction, providing evidence that the hand was aimed toward the target. Additionally, changes in movement direction made after the commencement of the movement tended to curve the hand path toward the target, providing evidence of error correction. Local minima of hand speed evident within segments of continuous motion were associated with turn toward the target. However, the movement path was also curved toward the target within the movement elements bounded by these minima. This finding was seen as consistent with "continuous" correction of movement errors and as contrary to the suggestion that infant movements are concatenations of ballistic movement units whose boundaries are marked by troughs in the speed profile.

Attention↗
PubMed1989

Splenectomy in patients with AIDS.

To establish the indications for splenectomy in patients with human immunodeficiency virus (HIV) infection we retrospectively analyzed 12 patients who underwent splenectomy. Patients with HIV infection who had immune thrombocytopenic purpura (ITP) were excluded as they had no splenomegaly and a definite indication for splenectomy exists in some of these patients. All 12 patients were anemic; 6 were thrombocytopenic and 6 leukopenic. All patients had splenomegaly and all were febrile. At surgery 3 patients were found to have Mycobacterium avium intracellulare (MAI) infection; 2 had splenic abscess due to Salmonella group D; 1 each had cytomegalovirus (CMV) splenitis and localized Kaposi's sarcoma (KS) of the spleen. No definite histopathologic diagnosis could be made in five patients, all of whom had evidence of extramedullary hematopoiesis. The degree of splenic enlargement did not correlate with the outcome. Both clinical and hematologic improvements were achieved in patients with splenic abscess and in patients who had splenomegaly, anemia, and thrombocytopenia. The presence of either of these findings constitutes an indication for splenectomy. Anemia and/or leukopenia without thrombocytopenia failed to improve; the presence of MAI and active CMV infection also resulted in failure. The presence of either of these conditions may be considered a contraindication to splenectomy.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Neuronal gene expression in aluminum myelopathy.

1. Aluminum administration to susceptible animal species results in neurofilament accumulation in neuronal perikarya and proximal axons. Pathogenetic studies in vivo have shown that aluminum rapidly associates with neuronal chromatin. Whether the effect of aluminum on DNA components plays a role in the production of the neurofibrillary lesion remains unclear. 2. In this study we used Northern analysis and in situ hybridization to evaluate mRNA levels of specific neuronal and glial components in the rabbit spinal cord at various times following aluminum administration. 3. Our results show that (a) all neuronal mRNAs evaluated (neurofilament triplet components, neuronal-specific enolase, and amyloid precursor protein) are markedly decreased, with no decrease in glial fibrillary acidic protein; (b) the effect on neuronal gene expression occurs early and concurrently with the development of the neurofibrillary lesion and reverses rapidly after a single dose of aluminum; and (c) there is a direct correlation between the severity of the neurofibrillary lesion and the decrease in neuronal mRNA levels. 4. We interpret our results to mean that the accumulation of neurofilaments in this model is not due to a selective effect on neurofilament gene expression but may be due to an inhibition of genes coding for components involved in processing of neurofilament proteins.

Aluminum↗
PubMed1984

Diet, nutrition intake, and metabolism in populations at high and low risk for colon cancer. Composition, intake, and excretion of fiber constituents.

The role of fiber in human diet in preventing a number of chronic diseases has been a widely debated topic in recent years. The claim that populations at low risk for colon cancer generally consume a more fiber-rich diet than those at high risk, has been used to postulate a protective role for this group of substances. In this study we asked the question whether populations leading different dietary lifestyles and who are at varying risks for colon cancer show marked differences in their dietary and fecal profiles of various fiber components. Four study groups consisting of Seventh-day Adventist (SDA) pure vegetarians, SDA lacto-ovo vegetarians, SDA nonvegetarians, and a group of general population nonvegetarians were selected from the greater Los Angeles Basin area. Three-day composite diets, and stools were analyzed for neutral detergent fiber (NDF), hemi-cellulose, lignin, cellulose, cutin + silica, and pectin. The percentage composition and the daily intake and output of each of these components were computed for each population group. The dietary profile revealed a trend (not statistically significant) toward generally higher daily intake values among the vegetarian subgroups, neutral detergent fiber values in g/day: SDA pure vegetarians, 63.0 +/- 7.9; SDA-lacto-ovo vegetarians, 55.8 +/- 3.5; SDA nonvegetarians, 57.2 +/- 3.5; general population nonvegetarians, 52.5 +/- 4.9), lignin, cellulose, and pectin being the major contributors to this difference.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗