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Biomedical subjects

M Reddy

Publications and source records attributed to M Reddy.

At least 73 records · Page 4Linked to original sources
PubMed1997

Experimental peri-implantitis in consecutively placed, loaded root-form and plate-form implants in adult Macaca mulatta monkeys.

This study is part of an on-going project describing the character of round- and plate-form implants placed in a primate model. In this paper 20 loaded plate-form and 23 root-form implants were connected to prostheses and experimental peri-implantitis was induced by ceasing scaling procedures and placing braided silk ligature around the implants. Twenty-four prostheses utilizing natural teeth were studied for comparison. Clinical measurements were carried out monthly for 6 months and radiographic measurements at 3 and 6 months post-ligature placement and cessation of scaling. Both root-form implants and plate-form implants showed a significant loss of crestal bone height at 3 and 6 months after ligature placement (P < .001 after 6 months). The difference in bone loss between plate- and root-form implants, however, was not significant.

Alveolar Bone Loss↗
PubMed1996

Differential recognition by CD28 of its cognate counter receptors CD80 (B7.1) and B70 (B7.2): analysis by site directed mutagenesis.

CD28, which is a member of the immunoglobulin superfamily of molecules (IgSF), is a homodimer of two polypeptides containing a single V-like domain with short transmembrane and cytoplasmic regions. It serves as a co-signalling molecule for T cell activation through binding to its cognate counter-receptors CD80 and B70, expressed on antigen presenting cells. In the current study, we investigated the regions of CD28 which are involved in its interactions with CD80 and B70, using site directed mutagenesis, CD28 mAb epitope mapping, receptor based adhesion assays and direct binding of Ig-fusion proteins to cell surface receptors. Truncation or substitution of a stretch of a proline rich "hallmark" sequence, "MYPPPY", abrogates binding to CD80 or B70, while retaining CD28 mAb epitopes and cell surface expression. On an Ig-fold model of the CD28 V-domain, this fully conserved motif localizes to a CDR3-like region. Mutations introduced into other loops, including the CDRI-like and CDR2-like regions, had very little effect on CD80 or B70 binding. Mutations introduced within the predicted beta-strand regions caused loss of receptor expression. Conservative substitution of both the flanking tyrosine residues within the "MYPPPY" motif with phenylalanine, caused loss of binding to B70 but not to CD80. These results show that, although the same overall region on CD28 may be involved in the interactions with CD80 and B70, subtle but important differences distinguish recognition by the two molecules. These finding, along with previous observations on the differential pattern of expression and tissue distribution of CD80 and B70, support the contention that these molecules play distinct roles in the regulation of immune responses in vivo.

Abatacept↗
PubMed1996

Clinicohistopathological findings of gelatinous droplike corneal dystrophy among Asians.

We describe the findings in nine Asian-Indian patients with gelatinous droplike corneal dystrophy (GDCD). Most patients showed initial signs of bilateral decreased vision and photophobia at an early age. The siblings were affected in four cases, and parental consanguinity was recorded in seven cases. We classified the disease into three forms based on clinicopathologic findings. Clinically, the mild form of the disease was evidence by central subepithelial, whitish-yellow, nodular lesions that corresponded to the subepithelial nodular deposits seen histologically. In the moderate form, the lesions coalesced, forming central, diffuse subepithelial lesions with superficial vascularization. On histology, the amyloid deposits assumed a sheetlike distribution in the subepithelial regions and in the superficial stroma. Aggregates of chronic inflammatory cells and stromal neovascularization were seen in the adjacent stroma. The severe form presented as diffuse, whitish opacification of the cornea with extensive neovascularization and scarring. Histologically this form was characterized by a visible plaque of vascularized scar tissue that partly replaced the stroma and enveloped the amyloid deposits. Frequent, early recurrence of the disease was noted in the grafts. This study provides a detailed clinicopathologic description of GDCD from the Indian subcontinent. We also discuss previously unreported findings from the most advanced stage of the disease.

Adolescent↗
PubMed1996

Analysis of consecutively placed loaded root-form and plate-form implants in adult Macaca mulatta monkeys.

The present paper describes 36 consecutively treated non-human primates (Macaca mulatta) as part of a balanced block design study to examine osseointegration in root- and plate-form implants prepared by atraumatic preparation of bone. Clinical measurements around selected teeth and digital radiology were utilized to monitor periodontal disease and bone loss around root- and plate-form implants which were loaded with a fixed prosthesis. Results indicate that once monthly regimen of scaling and root planing can prevent attachment loss in natural teeth, serving as abutments of loaded bridges. Root-form implants exhibited a significant loss of crestal bone height during the first year (P < 0.03) while plate-form implants showed less loss in bone height. There was an increase in bone mass over time for root-form or plate-form implants. Both root-form and plate-form implants provided radiographic evidence of osseointegration in loaded bridges.

Alveolar Bone Loss↗
PubMed1996

Continuous infusion etoposide in advanced AIDS-related kaposi sarcoma.

We conducted a preliminary phase II clinical trial to determine the toxicity, response, and survival rate of 72-hour continuous infusion etoposide administered to patients with AIDS-related Kaposi sarcoma. Nine patients with biopsy proven and measurable disease AIDS-related Kaposi sarcoma were treated with a continuous infusion of etoposide at a dose of 100 mg/m2 per day for 3 days every 3 weeks. All patients were evaluated for toxicity, response, and survival employing the NCI Common Toxicity Criteria, and both the Eastern Cooperative Oncology Group (ECOG) and AIDS Clinical Trials Group (ACTG) response criteria. All patients enrolled had at least two on-study poor risk factors by ACTG staging criteria. A total of 17 cycles of therapy were administered. Thirty-five percent of cycles were associated with grade 3 or greater leukopenia. Infectious complications were common, and there was one toxic death. Two partial responses (22%) by ACTG criteria were observed (95% confidence interval, 0% to 51%). In the absence of objective responses using more strict solid tumor response criteria and toxicity encountered we believe further evaluation of a 72-hour continuous infusion schedule of etoposide in patients with advanced AIDS and poor risk Kaposi's sarcoma is not warranted.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Identification of residues in the V domain of CD80 (B7-1) implicated in functional interactions with CD28 and CTLA4.

The CD80 (B7-1) molecule is a 45-60-kD member of the immunoglobulin superfamily that is expressed on a variety of cell types of haematopoietic origin. CD80 can provide a critical costimulatory signal to T cells by interacting with the T cell surface molecule CD28. CD80 also binds to the CD28-related molecule CTLA4, which is expressed on activated T cells, Recently, additional ligands of CD28 and CTLA4 have been described in mice and humans. One of them, CD86 (B-70 or B7-2) was characterized at the molecular level. Although similar in predicted structure to CD80, it is distantly related in amino acid sequence. In this study, human CD80 mutants were generated and tested for their ability to maintain the interaction with CD28 leading to adhesion and enhanced IL-2 production. Two hydrophobic residues in the V-like domain of CD80 were identified as critical for binding to CD28 and are also important for the interaction with CTLA4. These residues are adjacent to the epitope of the BB1 antibody, which inhibits CD28-CD80 interactions. One of these residues, Y87, is conserved in all CD80 and CD86 cloned from various species. These results being to unravel the structural requirements for binding to CD28 and CTLA4.

Abatacept↗
PubMed1995

The predictive value of changes in serologic and cell markers of HIV activity for subsequent clinical outcome in patients with asymptomatic HIV disease treated with zidovudine.

OBJECTIVE: To determine if serologic marker responses to zidovudine treatment during the first year of antiretroviral therapy could predict subsequent HIV disease progression independently of absolute CD4 lymphocyte responses. METHODS: We conducted a case-control study in patients with asymptomatic HIV disease, who were initiating zidovudine therapy in a randomized, prospective trial. A total of 102 patients who progressed to AIDS or advanced AIDS-related complex and 177 randomly selected controls matched by baseline CD4 cell count and duration of follow-up had serum samples (from prior to and at 8, 16, 32 and 48 weeks of zidovudine treatment) assayed for acid-disassociated HIV p24 antigen, beta 2-microglobulin (beta 2M), neopterin, soluble interleukin (IL)-2 receptor, soluble CD4 protein and soluble CD8 protein. RESULTS: Median time to event for cases was 20.2 months; median follow-up on study was 35.4 months for controls. After controlling for absolute CD4 count at baseline, increased baseline serum concentrations of HIV p24 antigen, beta 2M, neopterin, and soluble IL-2 receptor were highly predictive of increased risk of HIV disease progression. In a multiple logistic regression model, controlling for baseline marker values, change in beta 2M consistently added independent value to change in CD4 count in predicting subsequent risk of disease progression. CONCLUSIONS: Monitoring serum immunologic markers, in particular beta 2M, in addition to absolute CD4 lymphocyte counts prior to and within the first 4 months after initiating dideoxynucleoside therapy can increase the accuracy of estimations of subsequent long-term risk of clinical HIV disease progression. This information may be useful to clinicians and patients who are making decisions about initiating or changing antiretroviral therapy.

AIDS-Related Complex↗
PubMed1994

Mycobacterium tuberculosis induces expression of P-glycoprotein in promonocytic U1 cells chronically infected with HIV type 1.

A productive infection with HIV-1 is associated with an increased expression of a 170 kd plasma membrane P-glycoprotein (P-gp), that functions as a metabolically active drug efflux pump, in human T and macrophage cell lines. In this investigation we show that phagocytosis of M. tuberculosis by U1 cells, that are chronically infected with HIV-1 but produce minimal or no virus, resulted in an expression of P-gp that was associated with increased production of HIV-1 p24 antigen. In addition, U1 cells that had phagocytosed M. tuberculosis accumulated significantly less intracellular isoniazid (INH) as compared to U1 cells. Furthermore, verapamil, that binds to P-gp, increased the intracellular accumulation of INH and the sensitivity of M. tuberculosis to INH. These data suggest induction of P-gp expression may be one of the host mechanisms for the development of multidrug resistant M. tuberculosis in HIV 1 infection.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1994

Psychological distress and natural killer cells in gay men with and without HIV infection.

OBJECTIVE: The variability of the decline in immune function among those infected by HIV raises the possibility that psychological factors might help to explain the differences. Since studies of other populations have shown natural killer (NK) cells to be affected by psychiatric conditions, the authors examined this relationship in the context of HIV infection, expecting to find fewer NK cells to be associated with greater psychological distress. METHOD: Forty-six HIV-negative and 74 HIV-positive gay men who were participating in a longitudinal study had NK cells enumerations performed (by staining for CD56) 36 months after entry into the study. Comparisons were made between HIV-negative, HIV-positive asymptomatic, and HIV-positive symptomatic men by using a variety of clinician-rated and self-report measures of psychological function and absolute NK cell number. RESULTS: HIV-negative men had more NK cells than the groups of HIV-positive men. The groups' measures of psychological distress did not differ in any clinically meaningful ways. In general, the presence of DSM-III-R diagnoses and the measures of distress did not relate to NK cell number. CONCLUSIONS: NK cell number is not related to measures of psychological distress in these gay men with and without HIV infection.

Adult↗
PubMed1994

Continuous infusion bleomycin in AIDS-related Kaposi's sarcoma.

PURPOSE: To determine the toxicity, response, and survival rate of 72-hour continuous infusion bleomycin administered to patients with AIDS-related Kaposi's sarcoma. PATIENTS AND METHODS: Seventeen patients with biopsy-proven and measurable-disease AIDS-related Kaposi's sarcoma were treated with a continuous infusion of bleomycin at a dose of 20 mg/m2/d for 3 days every 3 weeks. All patients were evaluated for toxicity, response, and survival using the National Cancer Institute common toxicity criteria, and both the Eastern Cooperative Oncology Group (ECOG) and AIDS Clinical Trials Group (ACTG) response criteria. Fourteen of 17 patients (82%) enrolled had at least two on-study poor-risk factors by ACTG staging criteria. RESULTS: A total of 59 cycles of therapy were administered. Only one cycle (2%) was complicated by an absolute neutrophil count less than 500, and there were no episodes of febrile neutropenia. Fifty-four percent of cycles were associated with fever during the infusion, and five cycles (8%) were complicated by grade 3 rash. There were no other clinically significant (> or = grade 3) toxicities. There were seven partial remissions (41%) by ECOG criteria (95% confidence interval, 18% to 64%) and 11 partial remissions (65%) by ACTG criteria (95% confidence interval, 42% to 88%). Three of five (60%) previously treated patients had a partial remission with this schedule of bleomycin. The median survival duration was 7 months, with a range of 2.5 to 25 months. CONCLUSION: This continuous infusion schedule of bleomycin is active in patients with advanced-stage AIDS-related Kaposi's sarcoma and has acceptable toxicity. This regimen should be further evaluated in patients with earlier stage Kaposi's sarcoma and as salvage therapy.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Evaluation of consecutively placed unloaded root-form and plate-form implants in adult Macaca mulatta monkeys.

The present paper describes 18 consecutively-treated non-human primates (Macaca mulatta) as part of a balanced block design study of 36 animals to examine osseointegration in root- and plate-form implants prepared by atraumatic preparation of bone. Clinical measurements around selected teeth and digital radiology were utilized to monitor periodontal disease and bone deposition around the unloaded implants. Once a month scaling procedures were utilized as a means of preventing further advance of periodontal disease. Results indicate that once-monthly regimen of scaling and root planing can prevent attachment loss of natural teeth and will not interfere with the healing of either type of implant; once-monthly scalings produce significant reduction in redness (P < .05) and reduced probing depths (P = .01). A second finding is that both root and blade implants show radiographic evidence of osseointegration in this primate model. The quantitative analysis demonstrates bone gain is not stabilized until 6 months after healing. The data may indicate that occlusal loading of mandibular implants at 3 months may be premature.

Alveolar Bone Loss↗
PubMed1994

Oxidative damage to the eye lens caused by cigarette smoke and fuel smoke condensates.

Cigarette smoking is reported to increase the risk of cataract. Likewise, the use of smoky cooking fuel is implicated in the etiology of cataract. In an effort to understand the cellular and molecular basis, the in vitro and in vivo cataractogenetic effects of these smoke condensates have been studied using isolated rat lenses and pigmented rats. Isolated capsulated rat lenses are incubated with cigarette smoke condensate (CSC) and firewood smoke condensate (FSC) for varying periods, with and without antioxidants, in the presence and absence of light. CSC and FSC permeate the lens capsule, impart colour and opacify the lens in a light- and dose-dependent manner. Antioxidants offer partial inhibition against the above damage. The condensates contain polycyclic aromatics which generate reactive oxygen species such as O2 photodynamically, and ppb levels of Fenton metal ions which induce oxidative reactions through .OH. Smoke induced damage possibly occurs through systemic absorption and transport of toxic components to several tissues, and specially into the lens, wherein the turnover is slow, leading to chronic accumulation causing oxidative damage to the constituent molecules and to consequent lenticular opacity.

Animals↗
PubMed1993

Changes in inflammatory mediators in experimental periodontitis in the rhesus monkey.

Ligature-induced periodontitis was monitored for 6 months in eight Macaca mulatta monkeys to examine clinical status, radiographic bone level, and crevicular fluid (CF) levels of prostaglandin E2 (PGE2), thromboxane B2 (TxB2), interleukin-1 beta (IL-1 beta), tumor necrosis factor alpha, and leukotriene B4 (LTB4). A split-mouth design was used, with eight ligated teeth and eight contralateral nonligated teeth which develop soft-chow-promoted (spontaneous) disease. Ligated sites experienced an average attachment loss of 0.94 mm per site and linear bone loss of 0.88 mm per site, with spontaneous-periodontitis sites experiencing approximately half the loss of ligated sites. The CF mediator levels showed increased levels of PGE2 and TxB2 at the ligated sites, as compared with the spontaneous sites, with no significant contralateral differences in the IL-1 beta or LTB4 responses. The concentrations of LTB4 in CF reached an early threefold peak over the baseline level at 1 month. By 2 months there was a statistically significant threefold elevation in CF-PGE2 in the ligated sites and a twofold elevation in the spontaneous sites as compared to the baseline level (P = 0.041 and 0.008, respectively). The monocyte product IL-1 beta increased sharply at 2 months and returned to the baseline level by 6 months at both ligated and nonligated sites. Tumor necrosis factor alpha in CF was below the limit of detection at all sites throughout the experiment (i.e., < 2 ng/ml). The selective elevation of both PGE2 and TxB2 in ligated sites, compared with levels in spontaneous sites, in the presence of similar levels of LTB4 and IL-1 beta provides further evidence that these molecules regulate the magnitude of the tissue-destructive response in progressive periodontitis.

Animals↗
PubMed1991

Use of digital radiography to demonstrate the potential of naproxen as an adjunct in the treatment of rapidly progressive periodontitis.

The effect of the non-steroidal anti-inflammatory drug, naproxen, in reducing periodontal disease activity was assessed in 15 patients with rapidly progressive periodontitis. All patients in this double-blind study were treated with scaling and root planing. Thereafter, 7 patients receiving 500 mg naproxen b.i.d. for 3 months, and 8 patients received placebo. Disease activity was assessed in three ways. First, alveolar bone height was determined using standardized radiography. Second, alterations in alveolar bone metabolism were assessed using 99m-Tc-methylene diphosphonate uptake prior to dosing and 3 months later. Finally, bone loss or gain was detected using digital subtraction radiography. In this study, conventional subtraction images were processed to isolate the area of change and superimpose the change on the original radiograph. This allowed determination of both the direction and location of osseous changes. There was significantly less bone loss as determined by analysis of bone height during the 3-month study in the naproxen-treated patients when compared to the placebo-treated patients (p less than 0.001). Radiopharmaceutical uptake was significantly reduced in the alveolar bone in patients receiving naproxen (p less than 0.03), whereas no significant change was observed in the placebo-treated patients. Furthermore, the subtraction radiographs showed a significant increase in the proportion of teeth demonstrating bone gain in the naproxen-treated group. These findings indicate that naproxen may be a useful adjunct to scaling and root planing in patients with rapidly progressive periodontitis.

Adolescent↗
PubMed1989

Conjunctival impression cytology for assessment of vitamin A status.

Ocular signs and serum vitamin A concentrations are commonly used for the diagnosis of vitamin A deficiency. Recently, impression cytology was suggested as a method for early detection of this condition. A clinical trial was conducted to compare the results of impression cytology with the other two indicators of vitamin A status. A total of 246 children aged 1-10 y were investigated. About 25% of the children with normal eyes showed abnormal cytology. Their mean vitamin A concentrations were significantly lower compared with those with normal cytology, which suggests that abnormal cytology reflects subclinical deficiency. After treatment with vitamin A, most of the children who had abnormal cytology at baseline examination showed improvement. These observations suggest that abnormal cytology is specific to vitamin A deficiency. Impression cytology is a relatively simple technique and can be used for assessing the magnitude of the problem, especially in communities where the prevalence of clinical disease is low.

Child↗