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Biomedical subjects

M V Reddy

Publications and source records attributed to M V Reddy.

At least 37 records · Page 2Linked to original sources
PubMed1996

Chemotherapeutic activity of benzoxazinorifamycin, KRM-1648, against Mycobacterium tuberculosis in C57BL/6 mice.

OBJECTIVE: To investigate the chemotherapeutic activity of benzoxazinorifamycin, KRM-1648, in comparison with rifabutin (RFB) and rifampin (RIF) against experimental tuberculosis. DESIGN: C57BL/6 mice were infected with 10(5)-10(6) colony forming units (CFU) of either drug-susceptible virulent Mycobacterium tuberculosis (H37Rv) or multi-drug resistant (MDR) M. tuberculosis strain (2230) and were treated from the next day (early treatment) or after 2 weeks following infection (established infection) with 20 mg/kg dose of each drug or none (untreated control). The efficacy of chemotherapy was assessed based on prevention of mortality and on CFU levels in the lungs and spleens. RESULTS: All three drugs prevented mortality for up to 28 weeks of observation, while all the untreated control mice died by 4 weeks. Analysis of CFUs revealed superior therapeutic activity of both KRM-1648 and RFB as compared to RIF against the drug-susceptible strain of M. tuberculosis under the early treatment protocol. Twelve weeks' treatment with KRM-1648 or RFB caused complete sterilization of the lungs. However, residual organisms started appearing in the spleens 6 weeks after cessation of treatment with RFB and 16 weeks after KRM-1648 treatment. In mice infected with a MDR strain of M. tuberculosis, which was susceptible in vitro to KRM-1648, the drug did not appear to have any activity. Since the MDR organisms did not multiply in vivo, and did not cause any mortality up to 28 weeks in the RIF-treated control mice, a state of semi-dormancy of the organisms which might prevail in vivo could be responsible for refractoriness to treatment with KRM-1648. CONCLUSIONS: KRM-1648 showed an excellent chemotherapeutic activity, as compared to RFB and RIF, against drug-susceptible tuberculosis. However, all three analogues were ineffective against infection with multi-drug resistant strain of M. tuberculosis.

Animals↗
PubMed1996

Treatment of intracellular Mycobacterium avium complex infection by free and liposome-encapsulated sparfloxacin.

Mycobacterium avium-M. intracellulare complex (MAC) is the most frequent cause of opportunistic bacterial infection in patients with AIDS. Previous studies have indicated that liposome-encapsulated aminoglycosides are highly effective in treating MAC infections in mice. We investigated whether the fluoroquinolone sparfloxacin is effective in treating MAC infection in the murine macrophage-like cell line J774. Sparfloxacin was encapsulated in the membrane phase of multilamellar liposomes composed of phosphatidylglycerol-phosphatidylcholine-cholesterol (1:1:1 molar ratio). MAC-infected macrophages were treated for either 24 h or 4 days with free or liposome-encapsulated sparfloxacin. Treatment with free or liposome-encapsulated sparfloxacin (6 micrograms/ml) for 24 h resulted in the reduction of the growth index to 25 and 30% of that of untreated controls, respectively. When cultures were treated for 4 days, free sparfloxacin reduced the growth index to 6% of that of the untreated control, while liposome-encapsulated sparfloxacin reduced it to 8% of that of the control.

Animals↗
PubMed1996

Polymerase chain reaction detection of Mycobacterium tuberculosis in formalin-fixed tissue.

Use of the polymerase chain reaction (PCR) to detect Mycobacterium tuberculosis in formalin-fixed, paraffin-embedded tissue would be of great diagnostic value. However, formaldehyde has been reported to decrease the efficiency of amplification by structurally altering the polynucleotide chain. We sought to determine the ability of the PCR assay to detect M. tuberculosis in formalin-fixed, paraffin-embedded tissue in a mouse experimentally infected with the H37Rv strain of M. tuberculosis. Lung tissue from the infected mouse was cultured to determine the number of organisms per gram of tissue. The remaining lung tissue was divided into eight portions, seven of which were fixed in 10% neutral buffered formalin for 24-h intervals over periods lasting from 1 to 7 d, and a control portion was placed in isotonic saline. The tissue samples were then paraffin-embedded, and sections were obtained from each tissue block for PCR analysis. We show that the PCR assay can detect as few as nine organisms in a 5-micron section of tissue, and that up to 7 d of fixation in 10% neutral buffered formalin has a negligible effect on the assay. The PCR assay can detect low numbers of M. tuberculosis organisms in formalin-fixed, paraffin-embedded tissue.

Animals↗
PubMed1996

Fractionation, analysis and diagnostic utility of Mycobacterium tuberculosis H37Ra excretory-secretory antigen in pulmonary tuberculosis.

Excretory-secretory antigen of Mycobacterium tuberculosis H37Ra (Mtb ES antigen) isolated from culture filtrate was partially purified by 6% trichloroacetic acid precipitation. The TCA supernatant fraction (Mtb EST antigen) was examined for its diagnostic use in the detection of tuberculous IgG antibody in human sera by stick Indirect ELISA. Using Mtb EST antigen, tuberculous IgG antibody was detected in 90% of smear positive and 71% of smear negative pulmonary tuberculosis cases and 10% of healthy and disease controls. Further fractionation of Mtb EST antigen by SDS-PAGE yielded four active antigenic fractions viz., Mtb EST-3,4,6 and 10. Diagnostic evaluation of these fractions showed Mtb EST-6 antigen fraction to be useful in detection of both smear positive and smear negative pulmonary tuberculosis cases with sensitivities of 94% and 78% respectively and specificity of 88%.

Antibodies, Bacterial↗
PubMed1995

In-vitro and intracellular activity of rifabutin on drug-susceptible and multiple drug-resistant (MDR) tubercle bacilli.

Rifabutin, a spiropiperidyl derivative of rifampicin, is approved for the prophylaxis of Mycobacterium avium infections in AIDS patients in the US, and for the treatment of M. avium infections, tuberculosis and multiple drug resistant tuberculosis in many countries. In the present study, rifabutin was compared with rifampicin for its activity against drug susceptible and multi-drug resistant tubercle bacilli by several in-vitro and macrophage studies. Rifabutin exhibited similar or greater in-vitro activity than rifampicin as judged by the minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and MBC/MIC ratios, as well as continuous exposure and post-antibiotic effect studies. Rifabutin has been shown to be active against some multiple drug resistant strains which were resistant to rifampicin. In macrophage studies with continuous exposure to the drug or when the drug had been removed after 24 h, rifabutin also demonstrated high activity which was better than RMP against intracellular tubercle bacilli. This long-acting intracellular anti-mycobacterial activity may explain, in part, the clinical efficacy of rifabutin.

Antibiotics, Antitubercular↗
PubMed1995

Filarial antibody detection in suspected occult filariasis in children in an endemic area.

A study was conducted in filarial endemic area for diagnosis of occult filariasis in various clinical conditions in children. Thirty-five age- and sex-matched controls (endemic-15, non-endemic-10, disease control-10), 16 classical lymphatic filariasis, and 92 occult filariasis (clinical conditions which fall in the spectrum of occult filariasis and suspected to be filarial), were subjected to peripheral night blood smear examination for microfilaria (mf) and stick ELISA test using mf ES antigen for filarial antibodies. In the control group none showed mf and only 3 per cent (1/35) among endemic control were positive for filarial antibodies. In classical filariasis 1 per cent (2/16) showed mf and 94 per cent (15/16) had filarial antibodies. In suspected occult filariasis 1 per cent (one case of arthritis) showed mf and 62 per cent (57/92) showed filarial antibodies. These consisted of tropical pulmonary eosinophilia 63 per cent (15/24), arthritis where no cause could be ascertained on investigation 64 per cent (27/42), nephrotic syndrome 69 per cent (11/16), acute glomerulonephritis with ASO < 200 units 38 per cent (3/8), and cardiomyopathy 50 per cent (1/2). Correlation with age showed that 80 per cent (4/5) of cases of arthritis seen in 0-4 years of age group and 82 per cent (11/9) of nephrotic syndrome in the 10-14 years of age group were positive for filarial antibody. Arthritis due to other causes and minimal change nephrotic syndrome are uncommon in these respective age groups. It is concluded that the role of filariasis in endemic areas in these disease states cannot be denied and needs to be studied further.

Adolescent↗
PubMed1995

Immunoprophylactic potential of a 120 kDa Brugia malayi adult antigen fraction, BmA-2, in lymphatic filariasis.

A 120 kDa antigen containing SDS-PAGE fraction BmA-2 isolated from Brugia malayi adult parasite was highly reactive with normal sera from filarial endemic area. BmA-2 was analysed for its prophylactic potential in in vitro and in vivo. Sera collected from BmA-2 immunized jirds induced a significant level (80 to 90%) of protection against infective larvae and microfilariae in in vitro ADCC assay as well as in in situ micropore chamber implantation studies. Mastomys natalensis immunized with BmA-2 showed a significant level of protective response against circulating microfilariae by clearing 90% of them from circulation by fifth day after challenge infection. Immunization of jirds with BmA-2 resulted in an enhanced level of antibody response against BmA-2 and 88% reduction in the development of the parasites to the adult stage. Passive transfer of immunesera from jirds immunized with BmA-2 to naive jirds resulted in 71% reduction in adult worm recovery as observed 90 days after challenge infection with B. malayi. On the other hand the passive transfer of non-adherent spleen cells from immune jirds did not show any significant effect on the development of parasite. Administration of jirds anti BmA-2 serum to microfilaraemic jirds showed a temporary decrease in microfilarial count which was increased to pretherapeutic level within 100 days and there was no effect on the adult worms. This implies that the immune protective effect of BmA-2 is mainly antibody dependent and active immunization with BmA-2 is effective against filarial infection.

Animals↗
PubMed1995

In vitro activity of the benzoxazinorifamycin KRM-1648 against drug-susceptible and multidrug-resistant tubercle bacilli.

We investigated the activity of benzoxazinorifamycin (KRM-1648) against several drug-susceptible and multidrug-resistant strains of tubercle bacilli. Since KRM-1648 is a rifamycin derivative, we included some strains of Mycobacterium tuberculosis resistant to rifampin (RIF) among the multidrug-resistant strains. For RIF-susceptible strains, the MIC of KRM-1648 was much lower than that of RIF (MICs of KRM-1648 and RIF at which 90% of strains are inhibited, < or = 0.015 and < or = 0.25 micrograms/ml, respectively). The MBC of KRM-1648 (range, 0.007 to 0.03 microgram/ml) was also much lower than that of RIF (range, 0.5 to 1.0 microgram/ml). Postantibiotic effect studies with KRM-1648 showed a rapid reduction in the CFU counts with an exposure of 24 h or more, and its sterilizing effect was maintained even up to 21 days thereafter. Parallel postantibiotic effect studies with RIF showed a less significant effect with a faster recovery of growth, and RIF failed to sterilize the organisms even after 72 h of exposure. KRM-1648 at 0.125 and 0.25 microgram/ml caused complete inhibition of intracellular growth of M. tuberculosis in J774 A.1 macrophages after 48 h of exposure. After a similar exposure time RIF at a concentration of 0.25 microgram/ml caused complete inhibition of growth, but a concentration of 0.125 microgram/ml caused only a 50% reduction in growth compared with that of controls at day 7. With 24 h of pulsed exposure of the intracellular organisms to 0.25 micrograms of the drugs per ml, KRM-1648 caused complete inhibition of intracellular growth, while RIF caused only moderate inhibition of intracellular growth. These findings suggest that KRM-1648 is a potentially useful drug for the treatment of tuberculosis.

Antibiotics, Antitubercular↗
PubMed1995

Chemotherapeutic activity of clofazimine and its analogues against Mycobacterium tuberculosis. In vitro, intracellular, and in vivo studies.

Clofazimine (CFM), a riminophenazine drug, is primarily used in therapy for leprosy and Mycobacterium avium infections. With an objective of identifying drugs active against Mycobacterium tuberculosis, including those with multi-drug resistance, we investigated CFM and nine of its chemical analogues. Among these, B746 and B4101 had better activity than CFM against six drug-susceptible and nine single/multiple drug-resistant M. tuberculosis strains. B746 also showed slightly better activity than CFM against intracellular M. tuberculosis in J774A.1 macrophages and was comparable to CFM in its in vivo activity against experimental tuberculosis in C57BL/6 mice. Interestingly, it caused less pigmentation in internal organs.

Animals↗
PubMed1995

Analysis and diagnostic use of Brugia malayi adult antigen in bancroftian filariasis.

Detergent-soluble antigens of Brugia malayi adult worms (BmA SDS S Ag) were analysed for their antigenic activity and potential use in diagnosis of bancroftian filariasis. Analysis of SDS-PAGE fractions of BmA SDS S Ag against antifilarial antibodies, that is, human filarial serum immunoglobulin G and anti BmA SDS S Ag antibody, revealed two active antigen fractions: BmA-6 and BmA-9. Antibodies raised to BmA-6 and BmA-9 were tested with antigens isolated from infected human body fluids such as circulating filarial antigen (CFA2), urinary filarial antigen (UFAC2) and hydrocele fluid antigen (HFA). Both antibodies showed high reactivity with CFA2-1, 6 and 9 as well as UFAC2-5, 6 and 9 antigenic fractions. In immunoblotting studies, anti BmA-6 antibody detected specific antigens of high microfilaraemic reactivity such as 120, 54, 26 and 22 kDa. In inhibition ELISA using anti BmA SDS S Ag antibody and antigen fraction BmA-6, filarial antigen was detected in 85% of microfilaraemic, 35% of clinical filarial and 20% of endemic normal sera samples. When anti BmA SDS S Ag antibody and BmA-9 were used, 80% of microfilaraemic, 35% of clinical filarial and 25% of endemic normal sera showed positive reaction for filarial antigen. The analysis of urine samples showed the presence of filarial antigen in 76 and 72% of microfilaraemic cases using BmA-6 and BmA-9 fractions respectively while only 20% of endemic normals were positive using both the antigen fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Immunomonitoring of filarial patients during DEC therapy in an endemic area: a seven-year follow-up.

A group of 27 Wuchereria bancrofti infected persons from an endemic area, who had undergone treatment with diethylcarbamazine (DEC), were followed for 7 years to understand its effect on microfilaraemia, immune status and on the recurrence of infection. Treatment with DEC was for 14 days (day 1, 1 mg kg-1 body weight, day 2, 2 mg kg-1 body weight and from day 3 onwards 6 mg kg-1 body weight) followed by one dose (6 mg kg-1 body weight) on days 360, 540 and at the end of years 2, 3, 4, 6 and 7. After a 2-year follow-up the patients were divided into two groups. Group A consisted of cases that showed no reappearance of microfilariae (mf) and Group B of those cases that showed reappearance of mf. Further follow-up in the next 5 years showed that none of the cases in Group A were positive for mf at any time. In contrast, mf were detected in Group B in 14, 15, 27 and 33% of the cases followed at the end of years 3, 4, 6 and 7 respectively. Both groups showed a decrease in filarial IgG antibody and mf excretory-secretory antigen levels in the initial 4 years followed by increased levels at the end of years 6 and 7. The reappearance of filarial antibody and antigen in 50-70% of Group A and 68-100% of Group B at the end of year 7 suggests the existence of active infection in these cases. No cases followed in this study developed clinical symptoms. This study shows that long-term DEC therapy and immunomonitoring of mf patients is essential in an endemic area for arresting transmission and prevention of pathology associated with clinical manifestations.

Animals↗
PubMed1994

Measurement of nuclear DNA modification by 32P-postlabeling in the kidneys of male and female Fischer 344 rats after multiple gavage doses of hydroquinone.

Oral administration of hydroquinone (HQ) to male Fischer 344 (F344) rats results in dose-related kidney toxicity beginning with mild enzymuria by 1 week, significant cell proliferation by 6 weeks, and nephropathy and an increase in the incidence of renal tubule adenomas after 2 years. Female F344 rats, B6C3F1 mice, Sprague-Dawley rats, dogs, and humans are resistant to the renal toxicity of HQ associated with repeated exposure. To determine the potential of HQ to induce covalent DNA adducts in the kidney, male and female F344 rats were given 0, 2.5, 25, or 50 mg/kg HQ by gavage for 6 weeks, and nuclear DNA isolated from kidneys was analyzed by the 32P-postlabeling assay. At 50 mg/kg, males, but not females, showed an increase in the rate of excretion of N-acetyl-beta-D-glucosaminidase, indicative of proximal tubular damage. Analysis of nuclear DNA preparations by the postlabeling assay showed that HQ does not produce covalent DNA adducts in the kidneys of male and female rats. The assay's lower limit of detection is 1 adduct in 10(9) to 10(10) DNA nucleotides. No treatment-related increases in background radioactivity levels on the chromatograms were seen at locations corresponding to the major in vitro adducts of HQ and p-benzoquinone. HQ treatment, however, resulted in the reduction of the levels of certain endogenous adducts (I-compounds), the biological significance of which is unknown.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Lack of DNA adduct formation in mice treated with benzene.

The potential of benzene to produce DNA adducts in B6C3F1 mice was investigated by the nuclease P1-enhanced 32P-postlabeling assay. The mice were daily treated i.p. with 500 mg/kg benzene in olive oil for 4 days, and the liver, mammary gland, and bone marrow were collected 24 h after the last treatment. Thin-layer chromatograms obtained with treated-tissue DNA specimens were qualitatively identical to those from corresponding olive oil-treated (control) tissue DNA. Quantitative evaluations revealed that there was no treatment-related increase in radioactivity on the chromatograms at or near the locations where the major in vitro adducts of phenol, hydroquinone and benzoquinone migrated. Benzene treatment, however, resulted in a decrease in the levels of certain endogenous adducts, the biological significance of which is unknown. Our results indicate that benzene treatment does not produce detectable levels of aromatic DNA adducts in mouse tissues.

Animals↗
PubMed1994

In vitro and in vivo synergistic effect of isoniazid with streptomycin and clofazimine against Mycobacterium avium complex (MAC).

SETTING: Isoniazid (INH), the powerful antituberculosis drug, has also been used in regimens for treating disease caused by Mycobacterium avium complex (MAC), an important opportunistic pathogen encountered in AIDS patients. Its use for treatment of MAC disease has also been endorsed by the American Thoracic Society. However some controversy has emerged recently in medical literature, discounting its role and even implying that its use is contraindicated in chemotherapy of MAC disease. OBJECTIVE: In view of the controversy, we investigated its in vitro and in vivo activity in combination with streptomycin (SM) and clofazimine (CFM) against MAC. DESIGN: In the in vitro studies, the minimal inhibitory concentrations (MIC) of individual drugs or combinations of INH and SM as well as INH and CFM were determined in a checker-board type study by both conventional and radiometric (BACTEC) methods. In vivo studies assessed the efficacy of chemotherapy with INH alone or in combination with either SM or CFM against MAC infection in beige mice. RESULTS AND CONCLUSIONS: While MICs of INH and SM were 12.5 micrograms/ml and 6.25 micrograms/ml respectively, complete inhibition of growth was seen at 1.56 micrograms/ml with the combination of both drugs. The synergistic effect was observed both in conventional and BACTEC methods. In vivo studies demonstrated elevated activity when INH was given along with SM or CFM. Based on these observations we stress that isoniazid has still a place in chemotherapy of MAC disease, at least until other potent drugs are discovered.

AIDS-Related Opportunistic Infections↗
PubMed1994

Rapid assessment of mycobacterial growth inside macrophages and mice, using the radiometric (BACTEC) method.

SETTING: Conventional methods of determining the growth and drug susceptibility of mycobacteria either in macrophages or in vivo are time consuming and laborious. OBJECTIVE: We sought to develop a simple and rapid method for assessing growth and susceptibility of mycobacteria in macrophages and in vivo. DESIGN: The radiometric (BACTEC) method was compared with the conventional method for rapid assessment of growth and susceptibility of Mycobacterium avium complex (MAC) to clofazimine (CFM) and its two analogues (B4100 and B4101) in macrophages and in beige mice. RESULTS AND CONCLUSIONS: A linear relationship was observed between growth index (GI) readings by the BACTEC method and the colony forming unit (CFU) counts obtained by conventional plating on 7H11 agar in vitro of lysates from infected macrophages and of homogenates from the infected organs. There was also a good agreement between the two methods with respect to susceptibility of MAC to CFM and its analogues both in macrophages and in spleen. The BACTEC method, in addition to being quick and simple, was found to be more consistent. Our studies thus demonstrate that the radiometric method has potential application in rapid screening of drugs for antimycobacterial activity in macrophages and in animals besides its established value in in vitro screening.

Animals↗