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Biomedical subjects

S Singh

Publications and source records attributed to S Singh.

At least 343 records · Page 19Linked to original sources
PubMed2000

Intellectual psycho-educational and functional status of low birth weight survivors beyond 5 years of age.

To determine the intellectual, psycho-educational and functional status of low birth weight (LBW) survivors (birth weight < or = 2000 gms) beyond 5 years of age and to compare their status with normal birth weight counterparts. This was cross-sectional study. On hospital based cohort on longitudinal follow-up at the High Risk and Well Baby Clinics of a teaching hospital. The demographic data of these children was recorded. A detailed physical examination was performed. The tests of cognition included the Stanford Binet and the Raven's Progressive Matrices. Academic achievement was evaluated by the Wide range achievement test-Revised (WRAT-R). Assessment of visuo motor integration was done by the Bender Gestalt Test. The proportion of children having soft neurological signs was determined. Vineland Social Maturity Scale was performed on all children. Fifty-nine LBW children and fifty-seven matched control children participated in the study. 27 of LBW children were examined at a mean age of 7.0 +/- 1.1 years (group I) and 32 were examined at a mean age of 10.6 +/- 1.2 years (group II). The LBW children as a group performed in the normal range on the tests of cognition and academic achievement, but were significantly disadvantaged (p < 0.005) as compared to controls. A higher percentage of LBW children had low scores on the Bender Gestalt. Test as compared to controls but the difference was not significant. A significantly higher proportion of LBW children of both the groups showed the presence of soft neurological signs as compared to controls. The social quotient as assessed by the vineland Social Maturity Scale was significantly lower in the LBW children as compared to controls. Thus, though the LBW children were performing in the normal range on various measures, comparison with the control group showed that they were clearly disadvantaged on nearly every measure tested, emphasizing the need for early detection and referral for special education.

Child↗
PubMed2000

Optimization of tumor radiotherapy. Part VI: Modification of tumor glucose metabolism for increasing the bioavailability of 2-deoxy-D-glucose (2-DG) in a murine tumor model.

AIM: Differential radiomodification induced by 2-deoxy-D-glucose (2-DG) is proving to be a feasible modality for optimizing tumor radiotherapy. Our earlier work on Ehrlich ascites tumor cells has shown that pretreatment with hematoporphyrin derivatives increases the uptake and phosphorylation of 2-DG. Moreover, the alteration induced in bioenergetic profile was more drastic and less reversible. The promising combination of hematoporphyrin derivatives and 2-DG has been further evaluated in the Ehrlich ascites tumor bearing mice for determining the effects on radiotherapeutic response. MATERIALS AND METHODS: Solid tumors (average volume = 0.9 +/- 0.1 cm3) implanted in Swiss-albino strain "A" mice were focally irradiated (10 Gy) using 60Co teletherapy. Drugs were administered intravenously. Tumor bioenergetics was assessed by 31P MR spectroscopy. RESULTS: The uptake and phosphorylation of 2-DG was observed to be increased following pretreatment with hematoporphyrin derivatives. Upon hematoporphyrin derivatives + 2-DG treatment followed by irradiation, the intracellular pH reduced and a remarkable increase in glycerophosphorylcholine and inorganic phosphate levels was observed. CONCLUSION: The present study demonstrates the potential of hematoporphyrin derivative pretreatment in increasing the bioavailability of 2-DG in a mice Ehrlich ascites tumor model. The finding may have interesting clinical implications in the form of increased manifestation of the radiation-induced damage in the case of use of these drugs as a potential adjuvant in radiotherapy of tumors.

Animals↗
PubMed2000

Instructing subjects to make a voluntary response reveals the presence of two components to the audio-vocal reflex.

Previous findings have shown that subjects respond to an alteration, or shift, of auditory feedback pitch with a change in voice fundamental frequency (F0). When pitch shifts exceeding 500 ms in duration were presented, subjects' averaged responses appeared to consist of both an early and a late component. The latency of the second response was long enough to be produced voluntarily. To test the hypothesis that there are two responses to pitch-shift stimuli and to clarify the role of intention, subjects were instructed to change their voice F0 in the opposite direction of the pitch-shift stimulus, in the same direction, or not to respond at all. In a second group, subjects were tested under the above conditions as well as under instructions to raise voice F0 or to lower F0 as rapidly as possible upon hearing a pitch shift. Results showed that, when given instructions to produce a voluntary response, subjects made both an early vocal response (VR1) and a later vocal response (VR2). The second response, VR2, was almost always made in the instructed direction, whereas VR1 was often made incorrectly. The latency of VR1 was reduced under instructions to respond to feedback pitch shifts by changing voice F0 in the opposite direction, compared with that when told to ignore the pitch shifts. Latency and amplitude measures of VR2 differed under the various experimental conditions. These results demonstrate that there are two responses to pitch-shift stimuli. The first is relatively automatic but may be modulated by instructions to the participant. The second response is probably a voluntary one.

Acoustic Stimulation↗
PubMed2000

The production of hemicellulases by Thermomyces lanuginosus strain SSBP: influence of agitation and dissolved oxygen tension.

Shake-flask cultivation of T. lanuginosus strain SSBP on coarse corn cobs yielded beta-xylanase levels of 56,500 nkat/ml at 50 degrees C, whereas other hemicellulases (beta-xylosidase, beta-glucosidase, and alpha-L-arabinofuranosidase) were produced at levels less than 7 nkat/ml. Cultivation on D-xylose yielded much lower levels of xylanase (350 nkat/ml), although other hemicellulase levels were similar to those produced on corn cobs. The influence of agitation rate and dissolved oxygen tension (DOT) on hemicellulase production was studied further in a bioreactor. On xylose, xylanase activities of 4,330 nkat/ml and 4,900 nkat/ml were obtained at stirrer speeds up to 1,400 rpm to control DOT. At a constant stirrer speed of 400 rpm, xylanase activities of 10,930 nkat/ml and 15,630 nkat/ml were obtained when cultivated on xylose and beechwood xylan respectively, despite DOT levels below 5% for the duration of fermentation. The results indicate that there is an interaction between agitation rate and DOT, impacting on xylanase and accessory enzyme production. Higher agitation rates favoured the production of xylosidase, arabinofuranosidase and glucosidase by T. lanuginosus strain SSBP, whereas the lower agitation rates favoured xylanase production. Rheological difficulties precluded cultivation on corn cobs in the bioreactor. Volumetric xylanase productivities of 1,060,000 nkat/l x h and 589,000 nkat/l x h obtained on beechwood xylan and xylose indicate that T. lanuginosus strain SSBP is a hyperxylanase producer with considerable industrial potential.

Ascomycota↗
PubMed2000

Isolation and characterization of the thylakoid membranes from the NaCl-resistant (NaCl(r)) mutant strain of the cyanobacterium Anabaena variabilis.

NaCl-induced changes in the thylakoid membrane of wild-type Anabaena variabilis and its NaCl(r) mutant strain have been studied. Biochemical characterization of the thylakoid membrane was done by taking its absorption and fluorescence spectra at different wavelength. The thylakoid membranes of both strains were isolated by mechanical disruption of the freeze-dried and lysozyme-treated cells, followed by differential and density gradient centrifugation. The light absorption spectra of the thylakoid membrane showed three and two peaks in NaCl(r) mutant strain and its wild-type counterpart respectively at wavelengths of 400-850 nm. These peaks revealed that the thylakoid membrane contains a large amount of carotenoid and chlorophyll a. Fluorescence emission spectra of thylakoid membrane of NaCl(r) mutant and its wild-type strain at excitation wavelength of 335 nm showed two different peaks, one at 340 nm and the other at 663 nm respectively. The light absorption and fluorescence spectra of the thylakoid membrane also revealed that the membrane contained carotenoid pigment, chlorophyll (Chl) a, and a pigment with an emission peak at 335 nm. The HPLC analysis of the pigments of the thylakoid membrane indicates that the NaCl(r) mutant strain under NaCl stress contained an additional peak for the carotenoid pigment, which was lacking in its wild-type counterpart. The major peak in thylakoid membrane was that of echinenone and beta-carotene. Whereas the polypeptide composition of thylakoid membrane differed in the wild-type and its NaCl(r) mutant strain, no difference in the cell wall protein pattern was observed in both strains. The thylakoid membrane of NaCl(r) mutant strain contained two additional protein bands that were absent in its wild-type counterpart. The thylakoid membrane of the wild-type and its NaCl(r) mutant strain also showed morphological variations under NaCl stress.

Anabaena↗
PubMed2000

The use of lasers in benign prostatic enlargement.

This article reviews the laser techniques available for the treatment of lower urinary tract symptoms. Early data on short-term mortality, morbidity, complication rates, and outcome are available, but information on cost-effectiveness, long-term outcome, and patient preference are as yet unavailable. In the 8 years since laser methods became popular it has become clear that substantial and variably durable flow and symptomatic responses are achieved that do not quite match transurethral resection of the prostate (TURP). Less immediate physiologic stress is balanced by a delay before full response. Same-day surgery may be possible, but an extended period of catheterization may be necessary. Laser methods remain an option for treatment and are particularly applicable to the less fit man. Whether men will choose a less effective but less invasive treatment option for symptom relief is not yet obvious. Limited early data suggest the holmium laser technique most closely approaches the gold standard.

Humans↗
PubMed2000

Strong immunostaining for myogenin in rhabdomyosarcoma is significantly associated with tumors of the alveolar subclass.

Rhabdomyosarcomas are a heterogeneous group of tumors with respect to their molecular basis, degree of differentiation, histology, and clinical behavior. Because of the wide variation of tumor morphology, it is often difficult to distinguish between the distinct subtypes of rhabdomyosarcomas. By using cryosections of tumor specimens and immunohistochemistry, in the present study we show that strong expression of myogenin in rhabdomyosarcoma is associated with alveolar histology (P = <0.0001, Fisher's exact test). Although staining for myogenin was observed in 22 of 26 rhabdomyosarcomas, all alveolar rhabdomyosarcomas (nine of nine) showed high levels of staining for myogenin, as defined by the frequency and intensity of staining of the tumor cells. The staining pattern suggests that the tumor cells are clonally derived from myogenin-positive progenitor cells. In contrast, most embryonal rhabdomyosarcomas (13 of 15) were either negative or showed a low level of staining for myogenin. In these tumors a larger proportion of tumor cells were distinctly negative for myogenin. Six of seven alveolar rhabdomyosarcomas that strongly stained for myogenin were also positive for Pax3-7/Forkhead (FKHR) by polymerase chain reaction/reverse transcriptase-polymerase chain reaction. One of two embryonal rhabdomyosarcomas that strongly stained for myogenin was retrospectively found to be positive for Pax3/FKHR transcripts. Quantitative analysis for myogenin by Western blotting using a smaller subset of rhabdomyosarcomas revealed that in general there was a good correlation between immunohistochemical staining and Western blotting (P = 0.01, Pearson Correlation), although the former technique was more sensitive for detecting tumors with low levels of the protein. On average, alveolar rhabdomyosarcomas expressed at least threefold more myogenin than embryonal rhabdomyosarcomas. Our data show that staining for myogenin will be a simple, rapid, and accurate adjunct for distinguishing between alveolar and embryonal rhabdomyosarcomas. We propose that embryonal rhabdomyosarcomas result from an early block in myogenesis, before the expression of myogenin. In contrast, we propose that alveolar rhabdomyosarcomas either originate from a late block in myogenesis (after expression of myogenin) or that the pathological mechanisms involved in these neoplasms also induce strong expression of this protein.

Antibodies, Monoclonal↗
PubMed2000

HCO(3)(-) secretion in the rat colonic crypt is closely linked to Cl(-) secretion.

BACKGROUND & AIMS: The mechanism of colonic HCO(3)(-) secretion has not been established largely because of a lack of experimental methods for its detailed study. The present studies were designed to establish whether the isolated, perfused crypt of the rat distal colon is an excellent model to study HCO(3)(-) movement and the mechanism of colonic HCO(3)(-) secretion. METHODS: HCO(3)(-) secretion was determined in isolated, microperfused crypts by measuring [HCO(3)(-)] by microcalorimetry on nanoliter samples. RESULTS: Net HCO(3)(-) absorption was observed during lumen and bath perfusion with an HCO(3)(-)-Ringer solution. Vasoactive intestinal polypeptide (60 nmol/L), acetylcholine (100 nmol/L), or dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP, 0.5 mmol/L) induced active HCO(3)(-) secretion that required bath but not lumen HCO(3)(-)/CO(2). DBcAMP-stimulated HCO(3)(-) secretion was not affected by acetazolamide, an inhibitor of carbonic anhydrase. Removal of lumen Cl(-) did not alter DBcAMP-stimulated HCO(3)(-) secretion but reduced fluid secretion. DBcAMP-stimulated HCO(3)(-) secretion was closely linked to active Cl(-) secretion because HCO(3)(-) secretion was substantially reduced by removal of bath Cl(-), by addition of bath bumetanide, an inhibitor of Na-K-2Cl cotransport and Cl(-) secretion, and by addition of lumen NPPB, a Cl(-) channel inhibitor. CONCLUSIONS: These studies establish that colonic crypt HCO(3)(-) secretion (1) is not a result of an apical membrane Cl(-)-HCO(3)(-) exchange, (2) is tightly associated with Cl(-) secretion, and (3) primarily occurs via an apical membrane Cl(-) channel.

Absorption↗
PubMed2000

Morphine modulation of plasmodial-antigens-induced colony-stimulating factors production by macrophages.

Morphine abuse is known to cause immunosuppression and enhanced host susceptibility to malaria. We studied the effect of morphine on the Plasmodium berghei total-parasite-antigens soluble in culture medium (P.b.SA)-induced production of colony-stimulating factors (CSFs) by mouse peritoneal macrophages, in vitro. Morphine exerted a concentration-dependent biphasic modulatory effect; at 1 x 10(-4)-1 x 10 x 10(-6) M it slightly inhibited, whereas at 1 X 10(-8)-1 x 10(-10) M it augmented the production of CSFs. However, at 1 x 10(-12) M concentration the augmenting effect of morphine was significantly (p<0.05) diminished. Selective agonists of delta- (DPDPE) and mu- (DAGO) opioid receptors also respectively, inhibited and augmented the production of CSFs. The CSFs appear to be synthesized de novo as cycloheximide (50.0 microg/ml) completely inhibited their production. Naloxone ( 1 x 10(-5) M) lacked any effect on the inhibitory effect of morphine; however, at 1 x 10(-3) M it exerted partial blocking effect. Conversely, at 1 x 10(-5) M naloxone significantly (p<0.05) blocked the augmenting effect of morphine. These results suggest that morphine via opioid receptors, in a concentration-dependent biphasic manner, modulated the P.b.SA-induced de novo production of CSFs by macrophages, in vitro.

Adjuvants, Immunologic↗
PubMed2000

RT-PCR, nucleotide, amino acid and phylogenetic analyses of enterovirus type 71 strains from Asia.

A specific and sensitive method based on RT-PCR was developed to detect enterovirus 71 (EV71) from patients with hand, foot and mouth disease, myocarditis, aseptic meningitis and acute flaccid paralysis. RT-PCR primers from conserved parts of the VP1 capsid gene were designed on the basis of good correlation with sequences of EV71 strains. These primers successfully amplified 44 strains of EV71 including 34 strains isolated from Singapore in 1997 and 1998, eight strains from Malaysia isolated in 1997 and 1998, one Japanese strain and the neurovirulent strain EV71/7423/MS/87. RT-PCR of 30 strains of other enteroviruses including coxsackievirus A and B, and echoviruses failed to give any positive amplicons. Hence, RT-PCR with these primers showed 100% correlation with serotyping. Direct sequencing of the RT-PCR products of 20 EV71 strains revealed a distinct cluster with two major subgroups, thus enabling genetic typing of the viruses. The genetic heterogeneity of these strains culminated in amino acid substitutions within the VP1, VP2 and VP3 regions. The sequencing of a 2.9 kb fragment comprising the capsid region and the major part of 5' UTR of two Singapore strains revealed that they belonged to a group distinct from the prototype EV71/BrCr strain and the EV71/7423/MS/87 strain. The dendrogram generated from 341 bp fragments within the VP1 region revealed that the strains of Singapore, Malaysia and Taiwan belong to two entirely different EV71 genogroups, distinct from the three genogroups identified in another recent study.

Amino Acid Sequence↗
PubMed2000

Hyperglycemia, hyperlipemia, and periodic paralysis: a case report of new side effects of clozapine.

1. This case report of a Chinese male schizophrenic patient describes new side effects that have not been documented previously for patients treated with clozapine. At certain doses of clozapine, the patient showed direct adverse reactions, which include a combination of hyperglycemia, hyperlipemia, and periodic paralysis. 2. In a four-year study of this patient who had no previous episodes of diabetes in his or his family history, the authors found that these symptoms disappeared upon withdrawal of clozapine and relapsed with re-treatment of the drug. This study indicates that hyperglycemia, hyperlipemia, and periodic paralysis may need to be monitored on patients treated with clozapine.

Adult↗
PubMed2000

Expression of 5-HT(2A), 5-HT(2B) and 5-HT(2C) receptors in the mouse embryo.

Expression patterns of 5-HT(2A), 5-HT(2B) and 5-HT(2C) receptors during mouse embryogenesis were investigated using highly specific monoclonal antibodies. Differential and overlapping spatio-temporal patterns of 5-HT(2A), 5-HT(2B) and 5-HT(2C) receptor immunoreactivity were observed during active phases of morphogenesis of a variety of embryonic tissues, including neuroepithelia of brain and spinal cord, notochord, somites, cranial neural crest, craniofacial mesenchyme and epithelia, heart myocardium and endocardial cushions, tooth germs, whisker follicles, cartilage and striated muscle. The functional significance of these receptors was tested by exposing headfold stage mouse embryos to different subtype-selective 5-HT(2) receptor antagonists for 2 days in whole embryo culture. The most potent was the pan 5-HT(2) receptor antagonist ritanserin, which has high affinity for the 5-HT(2B) receptor. Ritanserin caused 100% malformed embryos at a dose of 1 microM. The 5-HT(2A/2C) receptor antagonist mianserin also caused a significant number of malformed embryos, but only when used at a 10 fold higher dose (10 microM). Ketanserin, which primarily targets 5-HT(2A) receptors, did not cause a significant number of malformed embryos at any dose tested. Together with previous evidence that 5-HT acts as an important morphoregulatory signal during mouse embryogenesis, present evidence for the early and continued expression of functional 5-HT(2) receptors throughout gestation raises the possibility that psychotropic drugs taken during pregnancy could interfere with developmental actions of 5-HT during prenatal development of neural and non-neural tissues.

Adsorption↗
PubMed2000

Phacoemulsification in eyes with white cataract.

PURPOSE: To study the results of phacoemulsification in eyes with white cataract. SETTING: Aravind Eye Hospital, Madurai, India. METHODS: This retrospective study comprised 212 consecutive patients with white cataract: 192 mature (90.6%), 11 intumescent (5.2%), and 9 hypermature (4.2%). Patients had phacoemulsification and continuous curvilinear capsulorhexis. After the nucleus was removed by the divide and conquer or the phaco chop technique, a posterior chamber intraocular lens was implanted. Preoperative and intraoperative findings, as well as postoperative outcomes, were analyzed. RESULTS: Intraoperative complications included premature entry of the tunnel into the anterior chamber in 4 eyes (1.9%), incomplete capsulorhexis in 60 (28.3%), posterior capsular tear in 4 (1.9%), conversion to a manual nonphacoemulsification technique in 4 (1.9%), intraoperative miosis in 7 (3.3%), and iris chafing in 2 (0.9%). Mean phacoemulsification time was 2.03 minutes (range 0 to 5.8 minutes). A best corrected visual acuity of 6/9 or better was attained in 131 patients (61.8%) on the first postoperative day and in 199 patients (93.9%) at 1 month. Postoperative complications included moderate transient striate keratopathy with corneal edema in 12 eyes (5.7%) and iritis in 2 (0.9%). CONCLUSIONS: Phacoemulsification was a safe and effective technique to remove white mature cataract in eyes in a developing country.

Adolescent↗
PubMed2000

Inhibition of L-DOPA-Cu(II)-mediated DNA cleavage by bilirubin.

It has been proposed that considerable DNA damage may be caused by endogenous metabolites produced during the body's normal metabolic processes. We have previously shown that L-DOPA, in the presence of Cu(II), leads to oxidative DNA breakage in vitro. Bilirubin is a degradation product of heme and is considered to possess antioxidant properties. In this paper we report that bilirubin inhibits L-DOPA-Cu(II)-mediated DNA cleavage to an appreciable extent of 50% at a concentration of 50 microM. Bilirubin was also shown to directly quench the generation of hydroxyl radicals by L-DOPA-Cu(II) to an extent of 30% at a concentration of 20 microM. The results support the putative antioxidant role of bilirubin in higher primates.

Animals↗