Biomedical subjects
Publications and source records attributed to B Singh.
The B- and T-cell antigenic sites on type O pili from Pseudomonas aeruginosa were determined by using an antipilus antibody competition assay and PAO-immune T-cell blasts in proliferation studies. The citraconylated tryptic digest III region (residues 54 to 120) was determined to be an immunodominant site for both T and B cells on the pilin molecule.
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Giant cell tumor of the tarsal bones is uncommon and therapeutic options are ill defined. We report on nine cases of giant cell tumors of the tarsal bones treated by excision of the complete bone in 6 cases, partial excision in 1 case, and curettage and bone grafting in two cases. There was no recurrence at an average 25.8-month follow-up. Function after calcanectomy was satisfactory. Excision of the talus may or may not be followed by arthrodesis, but arthrodesis is essential after excision of all the other tarsal bones except the calcaneus. We advocate aggressive surgical measures in these cases; amputation should be reserved for recurrences only. Satisfactory function may be expected after excision of tarsal bones.
In the mouse, the oocyte secretes a factor that enables cumulus cells to undergo expansion in response to epidermal growth factor (EGF) or FSH while expansion of the porcine cumulus oophorus has been shown to be independent of the oocyte. This study was undertaken to confirm independence of the porcine cumulus oophorus of the oocyte for its expansion and to determine if the porcine oocyte secretes the putative cumulus expansion-enabling factor that is required for FSH-stimulated mouse cumulus expansion. Porcine oocyte-cumulus cell complexes (P-OCC), oocytectomized oocyte-cumulus cell complexes (P-OOX) and intact clumps of cumulus cells (P-CCC) were cultured at 39 C in TCM-199 medium containing EGF (1 ng/ml) or FSH (1.5 micrograms/ml). After 24h culture periods, cumulus expansion was scored on an arbitrary scale of 0 to +4. EGF stimulated similar cumulus expansion (expansion score +3 compared to 0 for controls) in all the three groups. FSH stimulated cumulus expansion in significantly higher number of complexes in all groups compared to EGF. However, there was no difference in cumulus expansion among the three groups with EGF or FSH. To determine the production of the factor by the porcine oocyte, isolated clumps of cumulus cells of the mouse (M-CCC) were cocultured with porcine denuded oocytes (P-DO) in TCM-199 with or without 1.5 micrograms/ml FSH at 37 C for 24h. No expansion was observed when M-CCC were cultured alone in the presence of FSH or cocultured with P-DO in the absence of FSH. However, coculture of M-CCC with P-DO in the presence of FSH resulted in expansion of M-CCC similar to that observed in intact mouse oocyte-cumulus cell complexes (M-OCC) in response to FSH. These studies indicate that even though porcine cumulus expansion in vitro is not dependent on the oocyte, the porcine oocyte is capable of secreting cumulus expansion-enabling factor(s).
We present a sibship with a rare syndrome characterized by mental retardation, dense calcification of the lateral ventricular choroid plexus, and increased CSF protein. Neurophysiologic studies yielded nonspecific results, and endocrine studies, including parathormone levels, were normal. Simultaneous measurements of CSF and serum calcium, magnesium, and other electrolytes were normal, but the CSF/serum ratio of phosphate was low, suggesting a possible role in the pathogenesis of this syndrome.
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For some time now, microbial agents have been implicated in the etiology of autoimmune diseases, including insulin dependent diabetes mellitus (IDDM). Recent studies, however, have revealed that exposure of genetically diabetes-susceptible animals to certain microbes or microbial agents at an early age prevents the induction and progression of disease. This suggests that microbes may act to modulate the immunological status or immune repertoire of an individual genetically programmed for IDDM away from an autoimmune response. Immunization with microbial agents at an early age may offer an important new direction for the immunotherapy of IDDM.
The total protein and Ig content in the first colostrum was higher in buffalo cows than in dairy crossbred cows. Individual variation in Ig content of first colostrum may be responsible for differences in susceptibility of calves to infections. The decline in Ig content during subsequent milkings was faster in dairy crossbred cows. The major class was IgG in both species. Absorption of colostral proteins and Ig was 14.0 g (68%) and 4.6 g (75.4%), respectively, within 1 h of feeding colostrum to a 7-h-old female buffalo calf. Absorption was decreased to 2.1 and .83 g/h after the first feeding, suggesting that the intestinal absorption of macromolecules declined 1 h after the first feeding. Marginal placental transfer of maternal Ig also was demonstrated in buffalo. An albuminlike protein was predominant in blood plasma of the precolostral buffalo calf. This protein decreased, and IgG in blood plasma increased, after colostrum was fed, indicating that albuminlike protein may be involved in the transfer of maternal nutrients to the fetus.
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Haemangiopericytoma of the floor of the mouth with metastases to the lumbar spine in a 23-year-old black woman is described. She represents the 36th patient with oral cavity haemangiopericytoma and the 4th with a floor of mouth lesion. The aggressive behaviour of haemangiopericytoma and its resistance to all forms of recommended treatment was shown in this patient.
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Our previous studies have shown that vimentin can serve as a substrate for the v-Mos protein kinase in vitro. Furthermore, the amount of vimentin molecules in Moloney murine sarcoma virus (Mo-MuSV) transformed cells is decreased relative to uninfected cells and a lower molecular weight form is observed in these v-mos transformed cells (Singh & Arlinghaus, Virology 173: 144-156, 1989). Vimentin filaments are hyperphosphorylated and disassemble when cells enter mitosis. Here, we show that vimentin was coprecipitated with p85gag-mos from mitotic cell extracts by two different anti-Mos antibodies that do not crossreact with vimentin. However, we were unable to detect vimentin/v-Mos complexes interphase extracts, possibly due to lack of soluble vimentin. p37env-mos was also found to associate with purified bovine lens vimentin in vitro. The significance of these findings with regard to v-mos-induced cellular transformation is discussed.
Gastric duplication presenting as pyloric obstruction in an adult is reported. The diagnosis and management are discussed.
Two series of medorinone (3) analogs were prepared by modifications at C(2) and C(5). The C(2)-series was prepared from 2-chloro-5-methyl-1,6-naphthyridine (4) by replacement of the chloro group with various nucleophiles. The C(5)-series was prepared from 5-acyl-6-[2-(dimethylamino)-ethenyl]-2(1H)-pyridinone (11), 5-bromo-1,6-naphthyridin-2(1H)-one (17), and 1,3-diketones 19 and 27. 1,6-Naphthyridin-2(1H)-ones are novel inhibitors of cAMP PDE III. Modification of the carbonyl group of 3 or N-methylation at N(1) resulted in a dramatic loss of enzyme activity. Absence of the C(5)-methyl group of medorinone (3) or its shift to C(3) or C(7) also resulted in reduced activity. Substitution at C(3) also diminished activity. However, substitution at C(5) by a wide variety of substituents led to improvement of enzyme activity and several C(5)-substituted analogs were more potent than milrinone.
A general method to clone the HSP70 gene from any species employing polymerase chain reaction and degenerate oligonucleotide primers for conserved regions of this protein family is described. Using this method, a clone containing the entire coding sequence for the HSP70 gene from Clostridium perfringens, has been isolated and sequenced. The HSP70s from C. perfringens as well as other Gram-positive groups of bacteria contain a large deletion of 25 amino acids, near the N-terminal end, which is not seen in HSP70 from other sources.
Using degenerate oligonucleotide primers for conserved regions of HSP60, a 0.6 kilobase fragment of Clostridium perfringens DNA was amplified by the polymerase chain reaction. The amplified fragment was used as a probe to isolate a genomic clone containing the C. perfringens HSP60 operon. The clone contained two open reading frames homologous to the GroES and GroEL (or HSP60) family of bacterial and eukaryotic proteins as well as other upstream and downstream sequences. The approach described here, employing this set of degenerate oligonucleotide primers, could be used to clone HSP60 gene/cDNA from any species.
The pulmonary intravascular macrophages (PIMs) have been described in several species of animals. This study demonstrates for the first time that the equine lung has PIMs as resident phagocytes in its microvasculature. Their salient features such as globular surface coat, structures of the endocytic pathway, and related cell organelles closely resemble those of the calf, goat, and sheep. The exquisite organization of the coat globules in the form of a linear chain was structurally similar to the lipolytic lipase and the heparin-sensitive globular coat from PIMs of calf, goat, and sheep. Monastral blue (MB) when employed as a tracer to assess the phagocytic properties of equine PIMs induced similar modification of the globules of the coat into lipid droplets, reminiscent of neutral lipids. Lipids droplets (modified coat globules) were delivered into acid phosphatase-positive endosomes and lysosomes. Concurrently, the unaltered globules of the coat, probably internalized via fluid-phase constitutive pinocytoses, followed a different endocytic pathway. Large-scale platelet uptake by the PIMs was observed with thrombocytopenia in MB-treated ponies. The possible significance of hypothetical LDL-coat and the endocytic organelles as equivalents of synthetic apparatus of vasoactive lipids in the PIMs of horse needs to be assessed in future studies.