Search PubMed⌕ Search

Biomedical subjects

S Narang

Publications and source records attributed to S Narang.

70 records · Page 4Linked to original sources
PubMedDate not supplied

Synthesis of human insulin gene. VIII. Construction of expression vectors for fused proinsulin production in Escherichia coli.

We have constructed two families of plasmids suitable for the cloning of genes and for directing the synthesis of large amounts of fused proteins in Escherichia coli. The plasmids include the E. coli lac promoter and a portion of the coding sequence for beta-galactosidase, which can code for approx. 590 or 450 amino acids. The truncated beta-galactosidase gene ends with a poly-linker region at the 3' end, which can be cleaved by any one of the eight common restriction enzymes and joined to the gene coding for any desired protein. Each family includes three plasmids that enable fusion to be made in all three of the translational reading frames. We have cloned a synthetic human proinsulin gene into these plasmids, and 30% of the total E. coli protein was represented by the 590 amino acid-long truncated beta-galactosidase fused to proinsulin. The yield of proinsulin in this system is more than twice the amount produced by using a 1007 amino acid-long beta-galactosidase gene for fusion.

Base Sequence↗
PubMedDate not supplied

Esterases in the house fly. Polymorphisms and inheritance patterns.

Polyacrylamide gel electrophoresis was used to examine the variability and inheritance of esterases in five strains of the house fly, Musca domestica L. Individual zymograms exhibited 8 to 15 bands that could be assigned to one of five zones designated as A through E from anode to cathode. Correlations of P1-F1 banding patterns indicated the existence of at least 3 different loci in zone A. 2 each in zones B and C, and 4 in zone D; no clear inheritance patterns were discernable for the bands of zone E. Only the Es-5 locus of zone C was monomorphic in all of the strains studied. Eight loci possessed null alleles and codominant alleles were detected at six loci. The results suggest that esterases should prove useful for measuring relationships among fly populations or for various studies of population dynamics.

Alleles↗
PubMedDate not supplied

Isozymes of Culex p. fatigans. I. An esterase locus in linkage group III and its variability in natural populations.

Acrylamide gel electrophoresis revealed 19 frequent and 4 rare sites of esterase activity in various Brazilian populations of Culex p. fatigans. One pair of allozymes designated as Est-1 F and Est-1 S was selected for detailed investigation. Est-1 locus shows independent assortment from linkage group I marker, sex, and linkage group II markers, yellow and ruby, and therefore is assigned to linkage group III. Gene frequencies of Est-1 F varied from 0.49 to 0.92 in various Brazilian populations. Inhibition studies suggest that Est-1 F and Est-1 S are ali-esterases.

Animals↗
PubMedDate not supplied

Isolation of a sex-linked homozygous translocation in Anopheles albimanus.

A viable sex-linked homozygous translocation was isolated in Anopheles albimanus Wiedemann by using cytogenetic techniques and the X-linked marker, white eye. An examination of the meiotic chromosomes from ovaries established that the long arm of the X chromosome is involved in the translocation, and preparations of salivary gland chromosomes were used to confirm that the translocated arm of the meiotic X chromosome contains both euchromatin and heterochromatin. The translocated heterochromatin of the polytene X chromosome did not demonstrate an affinity for the chromocenter.

Animals↗
PubMedDate not supplied

Traumatic lens abscess with chornic endophthalmitis successfully treated with pars plana lensectomy and vitrectomy.

Intralenticular abscess is a rare entity and has been infrequently reported after surgery, metastatic infection, or trauma. We report a case of post traumatic lens abscess with low-grade endophthalmitis following a penetrating eye injury with a splinter of wood. The patient was successfully treated with a pars plana lensectomy and vitrectomy. Despite thorough microbiological investigations, no causative organism could be isolated.

Abscess↗
PubMedDate not supplied

Efficacy of various laser wavelengths in the treatment of clinically significant macular edema in diabetics.

BACKGROUND AND OBJECTIVE: To compare various laser wavelengths: argon green (514 nm), vs krypton red (647 nm), vs frequency doubled Nd:YAG (532 nm), and vs diode (810 nm), for laser photocoagulation treatment in clinically significant macular edema (CSME) in diabetics. PATIENTS AND METHODS: Four different wavelengths were used to sequentially treat 271 eyes of 164 diabetic patients with CSME. Follow up was conducted for a minimum of 6 months (9.8 +/- 1.3 months). Retreatment was performed if residual edema involving the foveal avascular zone persisted at 3 months. RESULTS: Reduction/elimination of CSME was observed in 93.3% of argon-treated eyes, 88.5% in krypton red group, 92.9% with frequency doubled Nd:YAG, and 84.8% with diode laser with no statistically significant difference between the groups (P > 0.05 for all groups). The number of eyes requiring retreatment was highest with the diode laser having 44.3% of eyes requiring retreatment and least with frequency doubled Nd:YAG having only 15.5% of eyes requiring retreatment (P = 0.0002). CONCLUSIONS: All lasers are equally effective in reducing/eliminating CSME. However, Nd:YAG may have an advantage because of requiring fewer retreatments.

Adult↗