Search PubMed⌕ Search

Biomedical subjects

M K Reddy

Publications and source records attributed to M K Reddy.

At least 55 records · Page 3Linked to original sources
PubMed1998

Cloning, expression and characterization of a gene which encodes a topoisomerase I with positive supercoiling activity in pea.

We have isolated and sequenced the full length cDNA for topoisomerase I. Using degenerate primers, based on the conserved amino acid sequences of five eukaryotic topoisomerase I, a 386 bp fragment was PCR amplified using pea cDNA as template. This fragment was used as a probe to screen a pea cDNA library. Two partial cDNA clones were isolated which were truncated at the 5' end. RACE-PCR was employed to isolate the remaining portion of the gene. The total size of the gene was 3055 bp with an open reading frame of 2676 bp. The deduced structure of pea topoisomerase I contain 892 amino acids with a calculated molecular weight of 100 kDa and an estimated pI of 9.3. A comparison of the deduced amino acid sequences of the pea topo I with the other eukaryotic topoisomerases clearly suggested that they are all related. Pea topoisomerase I has been overexpressed in E. coli system and the recombinant topoisomerase purified to homogeneity. The purified protein relaxes both positive and negative supercoiled DNA in the absence of divalent cation Mg2+. In the presence of Mg2+ ions the purified enzyme introduces positive supercoils a unique property not reported in any other organism except in archaebacterial topoisomerase I. Polyclonal antibodies were raised against recombinant topoisomerase I and western blotting with sub-cellular fractions indicated the localization of this topoisomerase in pea nuclei.

Amino Acid Sequence↗
PubMed1998

Clinicomicrobiological review of Nocardia keratitis.

PURPOSE: To present the clinical profile, laboratory results, and outcome of treatment in 16 patients with Nocardia keratitis. METHODS: A retrospective review of 16 culture-proven cases of Nocardia keratitis was done. Clinical and microbiologic data were analyzed. RESULTS: Nocardia constituted 1.7% of laboratory-confirmed bacterial keratitis and was seen predominantly in male subjects (13 of 16) with a mean age of 39.1 years. Although the predisposing factor was unknown in the majority, a definite history of trauma was present in four (25%) cases. Patchy stromal infiltrates were seen in 12 patients. Wreath pattern of infiltrates (six of 16) and hypopyon (nine of 16) were notable features. Nocardia was detectable in corneal scrapings of 10 patients with Gram stain and all patients with 1% acid-fast preparation (six of six). Nocardia asteroides was the causative agent in all except one (N. caviae). All isolates were sensitive to gentamicin; however, topical 30% sulfacetamide was the preferred drug for treatment. Favorable outcome (healed scar) was achieved in 11. CONCLUSION: Although Nocardia keratitis is a rare condition, a high index of clinical suspicion should be kept in agricultural workers or in patients with trauma who have patchy stromal infiltrates. Sulfonamides are the initial drug of choice, and gentamicin could be an effective alternative. If recognized early, Nocardia keratitis responds to medical treatment with good visual recovery.

Administration, Topical↗
PubMed1998

Antimicrobial effect of ciprofloxacin, povidone-iodine, and gentamicin in the decontamination of human donor globes.

PURPOSE: Clinical research addressing the issue of donor globe decontamination is yet to establish convincing data for the optimal choice of an antimicrobial agent. METHODS: In a donor-globe decontamination study, the antimicrobial effectiveness of a fluoroquinolone antibiotic (ciprofloxacin, 0.3%) was evaluated for the first time and compared with povidone-iodine (P-I, 5%) and gentamicin (0.3%). RESULTS: Ciprofloxacin and gentamicin were found to be less effective than P-I (p < 0.05) in converting culture-positive donor globes to culture negative. In eliminating coagulase-negative staphylococci that predominated the bacterial spectrum, again P-I scored better than ciprofloxacin (p = 0.003) and gentamicin (p = 0.006). Overall, P-I performed better than the other two in the 3-min decontamination procedure. Decontamination was carried out with the same agent for 15 min to assess the effect of duration of decontamination on the antimicrobial activity of P-I. With time, there was no significant increase in the antimicrobial efficacy of the agent except for Corynebacterium species. CONCLUSION: P-I continues to be the preferred agent for decontaminating donor globes. Whereas a contact of 3-min duration between P-I and donor globe remains satisfactory in decontamination procedures, corneal tolerance of this procedure needs investigation.

Anti-Bacterial Agents↗
PubMed1998

Efficiency and frequency of translational coupling between the bacteriophage T4 clamp loader genes.

The bacteriophage T4 DNA polymerase holoenzyme is composed of the core polymerase, gene product 43 (gp43), in association with the "sliding clamp" of the T4 system, gp45. Sliding clamps are the processivity factors of DNA replication systems. The T4 sliding clamp comes to encircle DNA via the "clamp loader" activity inherent in two other T4 proteins: 44 and 62. These proteins assemble into a pentameric complex with a precise 4:1 stoichiometry of proteins 44 and 62. Previous work established that T4 genes 44 and 62, which are directly adjacent on polycistronic mRNA molecules, are-to some degree-translationally coupled. In the present study, measurement of the levels (monomers/cell) of the clamp loader subunits during the course of various T4 infections in different host cell backgrounds was accomplished by quantitative immunoblotting. The efficiency of translational coupling was obtained by determining the in vivo levels of gp62 that were synthesized when its translation was either coupled to or uncoupled from the upstream translation of gene 44. Levels of gp44 were also measured to determine the relative stoichiometry of synthesis and the percentage of gp44 translation that was transmitted across the intercistronic junction (coupling frequency). The results indicated a coupling efficiency of approximately 85% and a coupling frequency of approximately 25% between the 44-62 gene pair during the course of infection. Thus, translational coupling is the major factor in maintaining the 4:1 stoichiometry of synthesis of the clamp loader subunits. However, coupling does not appear to be an absolute requirement for the synthesis of gp62.

Bacteriophage T4↗
PubMed1998

Mesothelial splenic cyst--a case report.

A 26-year-old male presented with a left upper abdominal mass of one year's duration. Ultrasonography revealed a cystic lesion arising from the lower pole of the spleen. Total splenectomy was done and pathological examination of the cyst confirmed a true cyst with mesothelial lining without squamous metaplasia. The epithelial linings of these true cysts ranged from flattened low cuboidal, low columnar to squamous type and unilayered or stratified. The pathogenetic hypotheses as well as clinicopathological features of this rare lesion, which is usually found in children and young adults, were reviewed.

Adult↗
PubMed1997

Fluorescent Gram stain in the microbiologic diagnosis of infectious keratitis and endophthalmitis.

PURPOSE: To verify the sensitivity of a recently described technique of fluorescent Gram stain (FGS) and evaluate its role in direct microscopic examination of clinical ocular samples. METHODS: In the first part of the study, culture suspensions of 10 bacterial isolates were stained, using FGS and conventional Gram stain (CGS), and were assessed for morphology, and Gram sign. In the second part, 39 corneal scrapings and 18 vitreous biopsy materials were stained and observed by both methods. RESULTS: Gram reaction and morphology of the bacteria, using CGS and FGS, were compared against culture. In both parts of the study, the sensitivity of CGS was significantly higher than FGS in the detection of Gram positive reaction (p = 0.01, 0.02). The specificities and predictive values of CGS and FGS were comparable in the evaluation of clinical samples. The bacterial morphology was demonstrated better (p = 0.01) with CGS. Significant quenching of fluorescence and change in Gram reaction with time were noted in FGS. CONCLUSIONS: The low sensitivity, quenching of fluorescence and change in Gram reaction presently preclude the usage of FGS as a diagnostic tool in ocular infections.

Endophthalmitis↗
PubMed1996

Comparison of ciprofloxacin ophthalmic solution 0.3% to fortified tobramycin-cefazolin in treating bacterial corneal ulcers. Ciprofloxacin Bacterial Keratitis Study Group.

PURPOSE: The purpose of the study is to compare the clinical efficacy and safety of ciprofloxacin ophthalmic solution 0.3% (Ciloxan) with a standard therapy regimen (fortified tobramycin, 1.3%-cefazolin, 5.0%) for treating bacterial corneal ulcers. METHODS: This randomized, parallel group, double-masked, multicenter study was conducted in 324 patients at 28 centers in the United States, Europe, and India. Patients were randomized into 2 treatment groups: 160 to ciprofloxacin and 164 to fortified tobramycin-cefazolin. Positive microbiologic cultures were obtained in 188 (58%) of 324 patients. Of these, 176 patients met protocol criteria and were evaluated for treatment efficacy: 82 in the ciprofloxacin group and 94 in the standard therapy group. The dosing schedule for both treatment groups was 1 to 2 drops of the first study medication (ciprofloxacin or fortified tobramycin) every 30 minutes for 6 hours, then hourly for the remainder of day 1; 1 to 2 drops every hour on days 2 and 3; 1 to 2 drops every 2 hours on days 4 and 5, followed by 1 to 2 drops every 4 hours on days 6 to 14. The second medication (ciprofloxacin or cefazolin) was instilled 5 to 15 minutes after the first drug, following the same dosing frequency. Physician's judgment of clinical success, cure rate, changes in ocular sings, and symptoms and the rate of treatment failures were the primary efficacy criteria. RESULTS: Topical ciprofloxacin monotherapy is equivalent clinically and statistically to the standard therapy regimen of fortified antibiotics. No statistically significant treatment differences were found between ciprofloxacin (91.5%) and standard therapy (86.2%) in terms of overall clinical efficacy (P = 0.34). Similarly, no differences were noted in resolution of the clinical signs and symptoms (P > 0.08) or the time to cure (P = 0.55). The incidence of treatment failures was less in the ciprofloxacin group (8.5%) compared with the standard therapy group (13.8%). Significantly fewer patients treated with ciprofloxacin reported discomfort than did patients treated with the standard therapy regimen (P = 0.01). CONCLUSION: Ciprofloxacin ophthalmic solution 0.3% monotherapy is equivalent clinically and statistically to standard therapy (fortified tobramycin-cefazolin) for the treatment of bacterial corneal ulcers and produces significantly less discomfort.

Adolescent↗
PubMed1996

Co-occurring adenoviral keratitis and hemorrhagic cystitis. A case report.

Adenoviruses are ubiquitous viruses, commonly causing ocular infections. They are also known to cause multisystem infections. External ocular infections caused by adenovirus are most often due to contaminated secretions. We report a patient in whom genitourinary symptoms developed and subsided along with ocular symptoms. Adenovirus was isolated on ocular culture. This is the first reported case of concurrent adenoviral keratitis and hemorrhagic cystitis. Eliciting a history of genitourinary and respiratory symptoms is important in patients with ocular adenoviral infections.

Adenoviridae Infections↗
PubMed1996

Two unusual nerve abscesses--lepromatous leprosy and pure neural leprosy: case reports.

We report two cases of nerve abscesses, one suffering from lepromatous leprosy (LL) and the other from tuberculoid neural leprosy. Neither had any signs of reactions. Both were untreated cases. Surgical nerve decompression and systemic prednisolone had resolved the nerve abscess in the first case, whereas the second one responded only to surgical nerve decompression. The unusual nature of clinical presentation of nerve abscess has been outlined.

Abscess↗
PubMed1996

Donor corneal tissue evaluation.

Proper evaluation of donor cornea is critical to the success of corneal transplantation. Attention must be paid to the cause of death and ocular condition as several general and ocular diseases constitute contraindications for donor corneal usage. Death to enucleation time should be noted. Gross examination and slit lamp biomicroscopy are mandatory for the evaluation of the donor eye while specular microscopy adds another useful dimension to information regarding donor cornea. This article provides a comprehensive review of all the aspects of donor corneal evaluation as practised today worldwide.

Contraindications↗
PubMed1995

Inhibitors of angiotensin-converting enzyme modulate mitosis and gene expression in pancreatic cancer cells.

The angiotensin-converting enzyme (ACE) inhibitor captopril inhibits mitosis in several cell types that contain ACE and renin activity. In the present study, we evaluated the effect of the ACE inhibitors captopril and CGS 13945 (10(-8) to 10(-2) M) on proliferation and gene expression in hamster pancreatic duct carcinoma cells in culture. These cells lack renin and ACE activity. Both ACE inhibitors produced a dose-dependent reduction in tumor cell proliferation within 24 hr. Captopril at a concentration of 0.36 mM and CGS 13945 at 150 microM decreased cellular growth rate to approximately half that of the control. Neither drug influenced the viability or the cell cycle distribution of the tumor cells. Slot blot analysis of mRNA for four genes, proliferation associated cell nuclear antigen (PCNA), K-ras, protein kinase C-beta (PKC-beta) and carbonic anhydrase II (CA II) was performed. Both ACE inhibitors increased K-ras expression by a factor of 2, and had no effect on CA II mRNA levels. Captopril also lowered PCNA by 40% and CGS 13945 lowered PKC-beta gene expression to 30% of the control level. The data demonstrate that ACE inhibitors exhibit antimitotic activity and differential gene modulation in hamster pancreatic duct carcinoma cells. The absence of renin and ACE activity in these cells suggests that the antimitotic action of captopril and CGS 13945 is independent of renin-angiotensin regulation. The growth inhibition may occur through downregulation of growth-related gene expression.

Adenocarcinoma↗
PubMed1994

Functional expression of rat peroxisomal acyl-CoA oxidase in Spodoptera frugiperda cells.

A cDNA coding the 661-residue rat peroxisomal fatty acyl-CoA oxidase (ACOX) has been constructed and expressed as catalytically active protein in Spodoptera frugiperda (Sf9) insect cells using baculovirus expression system. Recombinant viral clones were purified and the expressed protein was identified by immunoblotting and catalytic activity. In the rat liver, ACOX consists of three polypeptide components A, B and C, with relative molecular mass of 72 kDa, 51 kDa and 21 kDa, respectively. In Sf9 insect cells infected with the recombinant virus, ACOX protein (component A) was expressed up to 15% of the total cellular protein. Immunoblot analysis demonstrated that besides component A, components B and C were also present in Sf9 cells, suggesting that these components are derived from component A by post-translational proteolytic cleavage. However, unlike in rat liver, baculovirus generated ACOX in insect cells had reduced amounts of components B and C with an estimated molar ratio of A, B, C of 5:1:1 in Sf9 cells vs 1:5:5 in rat liver. By immunofluorescence and immunocytochemical methods the overexpressed recombinant ACOX was identified both in the cytoplasm and the nucleus of Sf9 cells. Polyclonal antibodies raised against recombinant ACOX recognized rat liver ACOX on immunoblotting. Baculovirus Sf9 system provides high-efficiency expression of functional ACOX and can be used to express specific mutant and truncated ACOX cDNAs for further characterization.

Acyl-CoA Oxidase↗
PubMed1994

Characterisation and mode of in vitro replication of pea chloroplast OriA sequences.

A partially purified replicative system of pea chloroplast that replicates recombinant DNAs containing pea chloroplast origin sequences has been characterised. Polymerisation by this system is very fast and insensitive to chain terminators like dideoxynucleotides, arabinosylcytosine 5'-triphosphate, etc. Both strands of template DNA are synthesized and single-stranded DNA templates undergo more than one round of replication. When sequences of either of the two chloroplast origins of replication (OriA or OriB) are used as templates, the replicative intermediates are found to have sigma structures. Electron microscopic analysis of the sigma structures restricted with various enzymes reveals that the initiation site of in vitro replication maps near the displacement-loop regions where replication initiates also in vivo. Although the observed replication initiation in the OriA recombinant template is chloroplast-DNA-specific, the mode of replication is different from that observed in vivo with intact ctDNA. However, when the template DNA contains both the OriA and OriB sequences, the in vitro replication proceeds in the theta mode, the mode of replication usually observed in vivo.

Chloroplasts↗