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Biomedical subjects

K Singh

Publications and source records attributed to K Singh.

At least 361 records · Page 20Linked to original sources
PubMed1993

A prospective trial of intraoperative fluorouracil during trabeculectomy in a black population.

In a study population of black Africans with advanced glaucoma in Ghana we conducted a prospective study of intraoperative 5-fluorouracil alone. Eyes undergoing trabeculectomy were randomly selected either to receive or not receive a single intraoperative application of 5-fluorouracil (50 mg/ml for five minutes). Fifty-five eyes had a mean follow-up of 282 days (minimum, 92 days). Twenty of 24 eyes (83%) in the 5-fluorouracil group vs 12 of 31 eyes (39%) in the control group had postoperative intraocular pressure of 20 mm Hg or less with or without medical therapy (P = .01). Eleven of 24 eyes (46%) in the 5-fluorouracil group and five of 31 eyes (16%) in the control group had intraocular pressure of 15 mm Hg or less (P = .02). Without medical therapy, 17 of 24 eyes (71%) in the 5-fluorouracil group and ten of 31 eyes (32%) in the control group had intraocular pressure of 20 mm Hg or less (P = .02). The overall complications were similar in the two groups. In this population, intraoperative 5-fluorouracil markedly improved the ability of trabeculectomy to lower intraocular pressure. We recommend that intraoperative 5-fluorouracil be considered in glaucoma surgery with poor prognosis as an alternative to postoperative subconjunctival injections when multiple injections are not feasible.

Adult↗
PubMed1993

[Brodie's abscess].

Brodie's abscess is a localized subacute or chronic osteomyelitis independent of any known previous acute infection. The entity is often mistaken for a bone tumour. The diagnosis requires biopsy. The treatment is curettage, drainage and antibiotics for a minimum of six weeks. We describe the characteristics of Brodie's abscess and describe a patient with an illustrating history, but with an unusual localization of the abscess (osilium).

Abscess↗
PubMed1993

Evaluation of liver function and lipid metabolism following Norplant-2 rods removal.

The effect of Norplant-2 rods on liver function and lipid metabolism was evaluated in 100 Singaporean women. As with the Norplant six-capsule, the only change noted in liver function was that of a significantly elevated bilirubin, which was within the normal clinical range for the local population. As regards lipid metabolism, the mean values for total triglycerides, cholesterol, LDL-cholesterol and HDL-cholesterol seen at the end of five years of Norplant-2 rod use and six months postremoval were similar to the preinsertion mean. As a result, the HDL-cholesterol/total-cholesterol-HDL-cholesterol and LDL-cholesterol/HDL-cholesterol ratio remained fairly constant. This indicates that the use of Norplant-2 rods does not directly contribute to cardiovascular risk.

Bilirubin↗
PubMed1993

Evaluation of hemostatic function following Norplant-2 rods removal.

Women using the Norplant-2 rod system in Singapore have been shown to have a change in their hemostatic function. There is a decrease in vitamin K dependent factors II, VII and a tendency toward lowered fibrinolytic activity after use of Norplant-2 rods. There was also an increase in platelet number and accelerated-platelet aggregation. These changes are similar to those seen with the Norplant six-capsule system and it would appear that both systems do not activate the coagulation system or enhance a state of hypercoagulation. On removal of the Norplant-2 rods at the end of 5 years, the significant changes seen in hemoglobin function observed with Norplant-2 rod use remained.

Adenosine Diphosphate↗
PubMed1993

Evaluation of liver function and lipid metabolism following Norplant implant removal.

A final evaluation of this longitudinal study involving 100 Singaporean women shows that, besides a significantly elevated bilirubin level, there is no other evidence of hepatocellular dysfunction with the use of Norplant implants. The elevated bilirubin levels remained significantly elevated six months after removal of the implant. Despite this, all values of bilirubin remained within the clinical range for the population studies. As regards lipid metabolism, total cholesterol, LDL-cholesterol and total triglycerides continued to remain below the pre-insertion mean at six months post-removal. The HDL-cholesterol showed a significant increase following removal of the implants. As a result, the HDL-cholesterol/(total cholesterol-HDL-cholesterol) ratio continued to remain above 0.200. This indicates that Norplant implants are not directly contributory to cardiovascular risk.

Bilirubin↗
PubMed1993

Evaluation of hemostatic function following Norplant implant removal.

Norplant implant use in Singapore showed a decrease in vitamin K-dependent Factors II, V, VII and reduction in fibrinolytic activity at the end of 5 years of use. Increased platelet numbers and accelerated platelet aggregation were also found throughout the 5 years of Norplant use. It thus appears that unlike the combined pill, prolonged Norplant use does not activate the coagulation system and does not enhance a state of hypercoagulation. On removal of the Norplant implants at the end of 5 years, the significant changes seen in hemostatic function observed with Norplant use remained.

Blood Coagulation↗
PubMed1993

Effective atomic number studies in different biological samples for partial and total photon interactions in the energy region 10(-3) to 10(5) MeV.

Effective atomic numbers (Zeff) of 7 different biological samples containing several elements were computed for total and partial cross sections using theoretical data over a wide range of energy region from 10(-3) to 10(5) MeV. It has been found that Zeff changes with change in composition of the material and change in energy. The significant changes in Zeff of different biological samples are due to domination of different interaction processes in different energy regions as number of elements present is quite large in some biological samples (e.g. cell, bone, muscle).

Bone and Bones↗
PubMed1993

Developmental expression of osteopontin (OPN) mRNA in rat tissues: evidence for a role for OPN in bone formation and resorption.

Osteopontin (OPN) is a 34-kDa, highly-phosphorylated glycoprotein with cell attachment properties that is a prominent constituent of the bone matrix. To aid in elucidating the function of this protein we have studied the cellular expression of OPN mRNA during the formation, growth and maturation of rat calvarial (membranous) and tibial (endochondral) bone. From Northern hybridization analysis OPN expression was demonstrated in the kidney and gravid uterus as well as in bone tissues. Compared to collagen, the expression of OPN was low in early bone formation but increased subsequently and reached peak levels in 14-day-old bone. However, both the collagen and OPN mRNAs decreased markedly thereafter and remained low in young adult bone. From in situ hybridization studies using a [35S]-labelled rat OPN cRNA probe, OPN mRNA was localized to osteoblastic cells in newly-forming calvariae, jaw bones, and in the metaphyseal and periosteal bone of the tibia. In contrast to bone sialoprotein (BSP), which is expressed almost exclusively by osteoblasts at sites of de novo bone formation, OPN transcripts were present in cells lining both endosteal and periosteal bone surfaces, and in osteocytes. Moreover, expression of OPN persisted during the subsequent growth and remodelling of both membranous and endochondral bone and was expressed at particularly high levels by bone cells and hypertrophic chondrocytes at sites of osteoclastic resorption. In the more mature bone of young adult rats OPN expression was significantly reduced but remained detectable in bone cells lining periosteal and endosteal surfaces and in the primary and secondary spongiosa of the tibia. These studies on the developmental expression of OPN support the concept of a multifunctional role for OPN in bone formation and remodelling. Thus, the expression of OPN by osteoblasts early in bone development is consistent with a role for this protein in the formation of bone matrix, whereas the peak expression of OPN later in bone development, together with high expression at sites of rapid remodelling, indicate that OPN deposited on the surface of mineralized connective tissues may provide a template for osteoclastic resorption.

Animals↗
PubMed1993

Does the ocs-element occur as a functional component of the promoters of plant genes?

The structural requirements of the ocs-element, a promoter element in several genes transferred to the host plant nucleus by Agrobacterium tumefaciens and certain DNA viruses, have been further characterized both in vitro and in vivo. Two adjacent and functionally identical protein-binding sites separated by an exact number of nucleotides are required for in vivo activity of the ocs-element. Plant pathogens have presumably recruited cellular transcription factors that interact with these binding sites to drive the high-level expression of their essential genes. Our functional analyses of the ocs-elements from two pathogen promoters define the structure of a sequence motif that might also be expected to occur in plant nuclear genes, and a search of the plant gene database has identified a number of plant gene promoters that contain sequences that resemble the ocs-element. These sequences were analysed for their ability both to bind the maize nuclear protein OCSTF and to activate transcription of an inactive promoter. A functional ocs-element was identified in only one of the plant genes, the soybean heat-shock gene, Gmhsp26-A. The apparent rarity of the ocs-element in plant genes contrasts with its frequent use by pathogens that transform the plant nucleus. Sequences resembling half of an ocs-element, on the other hand, are common in plant promoters and may form part of multi-element control motifs with a variety of regulatory functions. Plant pathogens may, therefore, have evolved to circumvent tight regulatory control of their promoters by the host by duplicating the half ocs-element promoter motifs to take advantage of the ubiquitous ocs-element-binding transcription factors in plants.

Agrobacterium tumefaciens↗
PubMed1993

Diarrhea associated with Aeromonas species in children in day care centers.

Outbreaks of diarrhea caused by enteropathogens have been reported in day care centers (DCC), but Aeromonas species have not been implicated. This study evaluated 381 children involved in 51 outbreaks in four DCC to determine the association of Aeromonas species with diarrhea and to characterize the isolates. The organism was identified in two outbreaks of diarrhea. In one, Aeromonas species were isolated from 6 (24%) of 25 children and in the other from 5 (21%) of 24 children. Seven other Aeromonas strains from children in DCC were studied. Fourteen (78%) of 18 were Aeromonas caviae and 15 were from children with diarrhea. Of the isolates, 75% did not have plasmids detected; all others had unique plasmid patterns. All strains had different DNA content. Twenty-two control isolates of Aeromonas from children with diarrhea in Mexico and Dallas had different chromosomal DNA patterns. Most Aeromonas infections were associated with symptoms. Chromosomal DNA patterns differentiated Aeromonas strains better than did plasmid DNA patterns. The outbreaks of diarrhea were unusual in that several different Aeromonas genospecies were involved in each outbreak.

Aeromonas↗
PubMed1993

Calcium-binding properties of osteopontin derived from non-osteogenic sources.

Osteopontin (OP), purified from rat bone, binds Ca2+ but whether different molecular forms of OPs derived from non-osteogenic sources and non-phosphorylated OP also possess this property remains to be determined. Furthermore, it is not known which specific site or sites of the molecule bind Ca2+. In the present study, following an established procedure, total proteins in the conditioned media from OP-synthesizing cell cultures were separated by SDS-PAGE, transferred to Immobilon-P membranes, and incubated with 45CaCl2, then Ca2+ ions bound to protein bands were analyzed by autoradiography. Purified OPs, and synthetic oligopeptides representing specific domains of the OP molecule were adsorbed on the membrane and processed as described above. Our results show that OPs synthesized by normal rat kidney cells, oncogenically transformed Rat-1 cells, OP purified from human milk, and non-phosphorylated OP secreted by 1 alpha, 25-dihydroxyvitamin D3-treated mouse epidermal JB6 cells all bind detectable levels of Ca2+ with specificity. We also show that a synthetic peptide representing the domain of OP which contains nine consecutive aspartic acid residues binds Ca2+ with specificity. It is probable, therefore, that a Ca(2+)-binding site resides in this region of the OP molecule. We conclude that Ca(2+)-binding is a general property of OP, irrespective of its molecular mass and origin, and the phosphate moieties of OP may not influence the conformation or accessibility of the Ca2+ affinity sites of the molecule.

Amino Acid Sequence↗
PubMed1993

Fluorescence line-narrowing studies of antibody-benzo[a]pyrene tetrol complexes.

Benzo[a]pyrene tetrol (BPT) was used as a fluorescent probe to investigate the nature of antigen binding by two different monoclonal antibodies (MAb) that recognize a variety of derivatives of anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10- tetrahydrobenzo[a]pyrenes (BPDE). Fluorescence line-narrowed spectra of the physical complexes of BPT formed with antibodies 8E11 and 3C3 were recorded at 4 K by employing vibronic excitation into the S1 electronic state. The frequencies of the vibrational modes of the S1 state were only marginally affected, though changes in relative intensities of some bands were observed. Fluorescence spectra recorded at 77 K by excitation into the S2 state showed that the (0,0) fluorescence emission of BPT was shifted to red on complex formation. Intensity ratios of the (0,0) band and the main vibrational band at 1300 cm-1 were used to assess the degree of interior binding of the chromophore. Quenching studies with acrylamide were employed to designate the complexes as type I, solvent inaccessible, or type II, solvent accessible. These studies also indicated that antibody 3C3 complexes tend to be more heterogeneous compared to the 8E11 complex. Deuterated BPT-d-12 also formed complexes with both antibodies, however, with different quenching behavior.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1993

Macrophage-mediated enterocyte damage in BALB/c mice infected with different strains of Giardia lamblia.

The mechanism of mucosal injury in Giardia lamblia-infected animals and humans is not well understood, although the role of gut macrophages in killing the trophozoites is well known. It is speculated, however, that macrophage products have a role in tissue injury and inflammatory response during infection, as in other inflammatory diseases. Therefore, in the present study an attempt was made to examine the mechanism involved in enterocyte damage during giardiasis. This was achieved using co-culture of enterocytes and gut macrophages obtained from infected BALB/c mice. The extent of tissue damage was assessed by measuring the marker enzyme of enterocyte damage, lactate dehydrogenase. To investigate the role of the various proteases and free oxygen radicals released by activated macrophages on enterocyte damage, inhibitors of various proteases and free oxygen radicals were used. Superoxide radical and certain proteases were found to have important roles in bringing about enterocyte damage during this infection in mice. Parasite load, lactate dehydrogenase release, and extent of lipid peroxidation were more pronounced in mice infected with symptomatic strains than in asymptomatic ones. The theory of inflammatory cell-mediated enterocyte damage in Giardia lamblia infection is proposed.

Animals↗
PubMed1993

Clinical evaluation of the effect of omeprazole, cimetidine, famotidine and ranitidine on histamine induced cutaneous wheal and flare response.

The effect of H2 receptor antagonists on immediate cutaneous response to allergens remain controversial. In the present study, the effect of 7-day administration of omeprazole, cimetidine, famotidine and ranitidine on histamine induced wheal and flare reaction was evaluated. A single blind randomized parallel group study with within patient comparison of responses was planned in non-ulcer dyspepsia patients eligible to receive H2 antagonists or omeprazole. None of the drugs produced any changes in the area of the wheal in comparison to respective baseline values. The area of flare was decreased by all the drugs and the percentage decrease in this parameter caused by omeprazole, cimetidine, famotidine and ranitidine was 2.4, 12.3, 20.2 and 13.2, respectively. Only famotidine caused a significant decrease in flare area (p < 0.05).

Adult↗
PubMed1993

Behavior development in normal neonates.

The behavior of normal neonates was studied on day 3, 10 and 30 of life with the help of Brazelton's Neonatal Behavioral Assessment Scale (NBAS). The behavior items were clustered and each cluster was scored. The cluster scores increased on subsequent observations in both term and preterm neonates, the increase usually being significant. The corresponding cluster scores were significantly higher in term babies than preterms. Preterms with questionable delay in development at 3 months of age had significantly lower 30th day scores in 3 of the 7 clusters.

Child Behavior↗
PubMed1993

Endoscopic removal of foreign bodies from gastrointestinal tract.

Forty-two children with ingestion of foreign bodies (FB) were managed conservatively. Thirty one (74%) of them were under 5 years of age. At presentation history revealed accidental ingestion in 95% and of being put in the oral cavity by elder sibs in 5% patients. Fifty seven per cent had respiratory distress, 38% had dysphagia and 12% had hematemesis. Foreign bodies were located in the gastrointestinal tract in the stomach (40%), esophagus (26%), small intestine (19%), duodenum (12%) and rectum (2%). A large majority of the FB were constituted by household objects. All the FB above the duodenojejunal junction and one in the rectum were retrieved successfully with fiberoptic endoscopes. In 19% patients, the FB had crossed duodenojejunal junction, and had come out in the stools during 4-5 days observation and these were mostly round in shape. Endoscopic procedures were carried out under intravenous diazepam or ketamine sedation. On endoscopic examination, 21% of them showed erosions in stomach and/or esophagus. No complications of endoscopic procedure or sedation were observed and none of the patients required surgical removal. Removal of FB with flexible fiberoptic endoscopes is less invasive and the best therapeutic option to avoid preventable complications of FB ingestion. In this procedure there is need of a trained and skilled Pediatric endoscopist with lot of patience and a good team work.

Child↗