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Biomedical subjects

S Gunasekaran

Publications and source records attributed to S Gunasekaran.

At least 55 records · Page 3Linked to original sources

Influence of carbon and nitrogen sources on glutathione catabolic enzymes in Candida albicans during dimorphism.

The effect of carbon sources, glucose and sucrose, and nitrogen sources such as ammonia, glutamate and L-citrulline on the activities of glutathione metabolic enzymes has been studied. Yeast and mycelial cells were used to identify changes in activity levels of glutathione reductase (GSSGR), glutathione transferase (GST), glutathione peroxidase (GPX) and gamma-glutamyl transpeptidase (GGT). Enzyme activities from cells grown in sucrose media were lower than in glucose media regardless of the enzyme tested, morphological form, or the growth interval. In all enzymes except GST, activity was higher in yeast form than in mycelia, regardless of nitrogen source, with lower activity from 24 to 72 h than at 96 h. In citrulline media, yeast form showed the maximum GST, GGT, and GPX activity. In ammonia-amended media, mycelia showed maximum activity in GGT, whereas in glutamate media, mycelia showed the maximum activity in GST. Also, the type of nitrogen source had no effect on GPX activity in the mycelial form. Finally, changing the nitrogen source showed no significant effect on GSSGR activity, either in the yeast or mycelial form.

Ammonia↗

Allopurinol reduces the severity of peritoneal adhesions in mice.

A study was designed to investigate the possibility of reducing peritoneal adhesion formation in mice by pretreatment with allopurinol. Allopurinol, at a dose of 35 mg/kg of body weight/d significantly reduced the severity of peritoneal adhesions (P < .001), and also the neutrophil response to ischemia (P < .05). Tissue myeloperoxidase activity at the site of ischemic injury was significantly lower in the allopurinol-treated mice at the end of 2 weeks (P < .001). However, xanthine oxidase was undetectable in both control and allopurinol-treated mice. These observations suggest that allopurinol reduces the severity of peritoneal adhesion formation in mice, possibly by reducing the neutrophil response to ischemia.

Allopurinol↗

Local increase in hyaluronic acid and interleukin-2 in the capsules surrounding silicone breast implants.

Connective tissue disease-like illness has been associated with silicone breast implants. However, no data are currently available on the immunopathology of the capsule surrounding the breast implants. Sera from women with breast implants were collected and assayed for interleukin-6 (IL-6), IL-2, and hyaluronic acid. Capsular biopsies were stained with a probe for HYA or with monoclonal antibodies specific for human macrophages (CD68), T cells (CD4), IL-6, and IL-2. Control specimens consisted of breast biopsies from women undergoing reduction mammoplasty. Our results revealed an increased local amount of hyaluronic acid in the capsule of patients with breast implants compared with control breast tissue. The HYA was localized extracellularly in areas containing fibrosis and cellular infiltrates. The infiltrating cells were determined to be primarily macrophages and T cells. No IL-6 was localized in any of the tissue sections. In contrast, large amounts of IL-2 were found in regions of infiltrating lymphocytes. No significant increase in IL-6, IL-2, or hyaluronic acid was found in the sera. The role of hyaluronic acid and cytokines in the inflammatory response in the capsules of silicone breast implants is discussed.

Breast↗

Early presentation of tuberous sclerosis as bilateral renal cysts.

We report on an infant in whom bilateral renal cysts were the only initial manifestation of tuberous sclerosis. We review the reported cases of infants with this association and emphasize that tuberous sclerosis can present in infancy as bilateral renal cystic disease. The role of the kidney biopsy in providing the correct diagnosis is discussed.

Female↗

Pharmacological study of isoproterenol and diabetic cardiomyopathies in rat right ventricular strips.

The present study was undertaken to compare the cardiomyopathies induced by experimental diabetes mellitus and chronic isoproterenol (ISO) pretreatment on inotropic reactivity of right ventricular strips from rats. One month after initiation of treatment, cardiac muscle was isolated and challenged with either the beta-adrenoceptor agonist ISO or the calcium channel activator Bay K 8644. Sensitivity and responsiveness to these agonists were determined. Crude membrane preparations were obtained from residual ventricular muscle and beta-adrenoceptor density determined using iodocyanopindolol. Isolated right ventricular strips from diabetic and ISO-treated rats demonstrated hyperresponsiveness to the inotropic effects of Bay K 8644 but subsensitivity to ISO. Ventricular beta-adrenoceptor density was found to be significantly depressed in membrane preparations from both diabetic and ISO-treated groups relative to controls. These data indicate that both forms of cardiomyopathy may affect inotropic reactivity through similar alterations to beta-adrenoceptors and calcium utilization.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

The role of ethnic relations and education systems in migration from Southeast Asia to Australia.

"After a brief discussion of the geographical, cultural, and historical characteristics of Southeast Asia [and Hong Kong], a review is provided of the evolution of Australian immigration policy which, in our view, is a strong pull factor. This is followed by stock and flow analyses of Asian-born residents in Australia. The motivations for emigration in countries which exhibit substantial emigration rates are considered next and the article ends with the conclusion that demand factors and social networks play a decisive role in the decision to emigrate." Factors affecting migration significantly include political conditions and ethnic relations in countries of origin, and educational and career opportunities in the country of destination.

Asia↗

Acinar cells free pure islets for transplantation from Indian bonnet monkeys.

Pancreatic islets, completely free of acinar cells were isolated from the Indian bonnet monkey Macaca radiata radiata for transplantation studies. The monkey pancreas was inflated with Hank's solution containing collagenase (5 mg/ml). After incubation for 25 min at 37 degrees C the friable pancreas was teased apart. The fragments were aspirated with a 20 ml disposable syringe (without needle) twice and ejected. After the third aspiration, the homogenate was poured over nylon mesh. Islets were separated from the filtrate by centrifugation in Ficoll gradients and then hand picked. Histological examination revealed that the islets were completely free of acinar cells. On exposure to glucose, the islets responded normally with increased insulin release. They retained their structural integrity after transplantation under the renal capsule of normal rats treated with cyclosporine. The deleterious effect of exocrine cells after transplantation will be completely eliminated by this islet preparation.

Animals↗

Cervical conization with frozen section before planned hysterectomy.

OBJECTIVE: To report our institutional experience with the accuracy and usefulness of cervical conization with frozen section before planned hysterectomy. METHODS: One hundred fifty-nine patients who planned to have hysterectomies for or with a concomitant diagnosis of cervical intraepithelial neoplasia (CIN) underwent preliminary cone biopsies with frozen section. The frozen and permanent pathologic diagnoses were compared retrospectively. Detailed analysis was directed at the indications for cone biopsy and the patients who were found to have invasive cancer. RESULTS: Among 108 patients with negative specimens or CIN, the frozen section was accurate within one degree of CIN in 106. Cone biopsy for a positive endocervical curettage, unsatisfactory colposcopy, or discrepant cytology did not contribute to the diagnosis of invasive cancer but did lead to an ultimate diagnosis of CIN III. One of 12 women with a frozen-section diagnosis of microinvasion had deeper invasion on permanent sections. CONCLUSIONS: Frozen-section evaluation of a cone biopsy carries a degree of accuracy that enables the surgeon to make an immediate decision about definitive therapy. Exact indications, use during pregnancy, and accuracy for the diagnosis of microinvasion require further study.

Adult↗

Evaluation of the cervical canal with the endocervical brush.

OBJECTIVE: To evaluate and compare the cytologic information obtained from the endocervical brush and the histologic information obtained from the standard endocervical curettage (ECC) used to evaluate the endocervical canal in patients with an abnormal Papanicolaou test. METHODS: Three hundred eighty-eight patients underwent evaluation of an abnormal Papanicolaou test with a repeat Papanicolaou test, a separate endocervical brush test, colposcopy, directed biopsies, and ECC. The study group comprised 101 patients who subsequently underwent conization and/or hysterectomy. The brush and ECC results were evaluated against the final pathologic findings. RESULTS: Sixty-five patients had a satisfactory colposcopy and 36 had an unsatisfactory colposcopy. Results for these two groups are reported separately. For the total group, the sensitivities of the ECC and brush were 49 and 93%, respectively (P < .001); the specificities were 82 and 26% (P < .001), the positive predictive values were 69 and 52% (P = .99), and the negative predictive values were 65 and 82% (P = .004). CONCLUSION: The endocervical brush appears to be a sensitive test for disease in the endocervical canal but yields a high false-positive rate. The role of the brush in this setting will require further study. The ECC is more specific but is also a suboptimal test for identifying disease in the endocervical canal.

Adolescent↗

Labour migration and policy formation in a newly industrialized country: a case study of illegal Thai workers in Singapore.

"Towards the end of 1988, the Singapore Government began to express concern about over-reliance of the economy on foreign workers and later about the presence of large numbers of illegal workers. This article examines the policies and legislation introduced to change these situations, and examines in detail the repatriation of 10,000 unauthorized Thai immigrants. In addition to economic policy and practice, the social and political aspects of migration and labour utilization are considered, as are the implications for international relations."

Asia↗

Delayed light emission as a means of quality evaluation of fruits and vegetables.

DLE is probably produced by all fruits, vegetables, and plant materials undergoing photosynthesis. However, the intensity and duration of the emitted light vary widely depending upon many factors. Because of the strong dependence of DLE on the chlorophyll content, variation in the DLE can be expected among different varieties of the same product. Therefore, quality evaluation based on DLE measurements require careful selection of measuring criteria such as duration and intensity of illumination, dark period, and temperature. It is necessary to obtain precise values of DLE for a particular product under a set condition; and the measurement conditions should be carefully validated to establish a standard measuring criteria. In general, the quality evaluation of fruits and vegetables is based on three major aspects: maturity and/or ripeness evaluation, composition analysis, and internal and external defect detection. DLE measurements so far have focused mainly on maturity evaluation because of the definite relationship between the emitted light and chlorophyll concentration, which changes with maturity. It should be noted that chlorophyll alone is not sufficient; it is the complex of in situ chlorophyll and related compounds in plant materials that jointly contribute to the DLE. Composition of fruits such as sugar content has been related to DLE. Recently, DLE measurements have been applied to detect certain physiological stress responses and defects such as chilling injuries. However, these areas of research have not yet been fully explored. Further investigation relating to compositional quality and internal and external defects of fruits and vegetables with DLE measurement may offer solutions to certain complex quality evaluation problems. The duration of DLE after excitation involves a matter of at least several seconds. From a mechanical standpoint, this extended period of light emission offers a convenient time in which to separate excitation and measurement. However, the exponential decay necessitates very precise control of time between illumination and measurement. The broad activation spectrum permits wide choice and simple design of excitation sources. However, size, shape, and varietal variations of plant materials make uniform DLE measurements difficult. It is suggested that DLE measuring instruments be designed to make several measurements over the entire surface of the specimen. An average of such measurements would reduce the effect of surface nature and shape of the product. Reporting the DLE intensity per unit surface area of the product will eliminate the dependence of area of excitation on DLE.(ABSTRACT TRUNCATED AT 400 WORDS)

Chlorophyll↗

Effects of extracorporeal shock wave lithotripsy on the structure and function of rabbit kidney.

An animal model was developed to investigate the effect of extracorporeal shock wave lithotripsy (ESWL) on a normal kidney. Rabbits were treated with 3,000 shock waves at 18 kV to each kidney. Blood and urine samples were collected daily before and after shock wave treatment. Serum levels of hemoglobin, creatinine, lactic dehydrogenase (LDH), creatinine phosphokinase (CPK), and total protein were determined. Urine determination of volume, total protein, hemoglobin, and creatinine were also made. All kidneys, after sacrifice, were subjected to histologic analysis. The average pre-treatment creatinine clearance of our rabbits was 8.3 ml./min. After the treatment, a significant (p less than 0.01) reduction in creatinine clearance was noted for four days. The reduction was to 0.61 ml./min. on day one, 0.87 on day two, 1.04 on day three, and so forth. Urine hemoglobin rose significantly (p less than 0.01) for the first three days from 0.0 to 1.5 gm./dl. Histologic examination at seven days showed focal subcapsular hemorrhage, tubular dilation, and interstitial hemorrhage. Histologic evaluation at two months revealed focal interstitial fibrosis. In conclusion, this study reveals that shock waves to the kidney have short term physiologic effects on renal function and permanent focal histologic effects, which do not effect long term physiologic function. Further research on the effects of ESWL on renal function and structure could be facilitated with the use of this model.

Animals↗

Adenocarcinoma of the jejunum in association with celiac sprue.

An increased incidence of small bowel lymphoma in patients with long-standing celiac sprue is well documented in the literature. Less common is the association of adenocarcinoma of the small intestine. We report a patient with celiac sprue who initially responded to a gluten-free diet. Eighteen months later, diarrhea, abdominal cramps, and bloating was found to have its origin in partial small bowel obstruction. At laparotomy, two distinct adenocarcinomas of the jejunum were resected. Celiac patients who initially respond to gluten withdrawal and subsequently suffer exacerbation while adhering to strict dietary therapy should be carefully evaluated for evidence of a small bowel malignancy.

Adenocarcinoma↗

Population change in Burma: a comparison of the 1973 and 1983 censuses.

"A comparison of the 1973 and 1983 censuses provides ample evidence of a decline in fertility in Burma [Myanmar]. The proportion of children in the population fell substantially in the ten-year period accompanied by a significant increase in the mean age at marriage as indicated by the higher female...mean age at marriage. An analysis of the regional variations in population density indicates inter-regional movement of population. While there is marked success in the literacy programmes as indicated by the sharp reduction in the prevalence of illiteracy, especially among the females, changes in the industrial and occupational structure of the labour force suggest worsening economic conditions. Under these circumstances, it is surmised that the fall in fertility, without any concerted government policy for inducing such a decline, may be a first-level and benign response of a more literate and hence more informed population to rising aspirations and the inability of the economy to accommodate these aspirations."

Asia↗

Collagen based biomaterials: an ideal way of increasing their resistance to infection.

Collagen and gelatin containing biomaterials are relatively more susceptible to bacterial infection. Systemic administration or local delivery of antibiotics after implantation does not seem to solve the problem either effectively or easily. Antibiotics may be incorporated in the implant; but many, being water soluble, are quickly absorbed and not effective for adequate time periods. Resorcinol monoacetate (RMA) is a relatively water insoluble antibacterial agent which partially crosslinks collagen and has the potential to be an intrinsic antibiotic in collagenous bioprostheses. This study confirms the efficacy of RMA as a chemical that: (a) mildly crosslinks collagen at pH 3.5-4.5; (b) releases very slowly from the pretreated collagen sponge when washed in aqueous medium; (c) inhibits bacterial growth on the pretreated collagen sponges, at 2% (w/w) concentration, for at least 12 days; (d) remains biocompatible under treated conditions.

Animals↗