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Biomedical subjects

M K Dasgupta

Publications and source records attributed to M K Dasgupta.

At least 37 records · Page 2Linked to original sources
PubMed1992

Significant reduction of peritonitis rate by the use of Twin-bag system in a Canadian regional CAPD program.

In a regional CAPD program in Northern Alberta, Canada, the peritonitis rates among patients undergoing CAPD treatment were quite high: 1/8.3 and 1/7.4 per patient month from a population of 75 and 76 patients in 1989 and 1990 respectively. Our patient population is comprised of different ethnic groups, separated widely from the dialysis centre; over half of them are above the age of 60 years. As it is not possible to change the patient characteristics in our centre, we switched to the Twin-bag disconnect system in 83 out of a total of 103 patients in 1991. With this change our overall peritonitis rate has significantly improved to 1/14 per patient months and 1/17 per patient months in patients using the Twin-bag system. This improvement in the peritonitis rate has occurred without any change in our patient characteristics. We find the improvement in our peritonitis rate is due to the use of the new Twin-bag system, which provides total disconnection with no spikes and thereby reduces peritonitis due to touch contamination.

Humans↗
PubMed1991

Catheter biofilms and recurrent CAPD peritonitis.

To study the significance of biofilm bacteria in CAPD peritonitis, in a preliminary study, we compared the growth of planktonic and biofilm bacteria by parallel cultures of the same PD effluent in 14 patients with CAPD-associated peritonitis. Planktonic bacteria were isolated by routine microbiologic culture techniques and biofilm bacteria by the use of a modified Robbins' device (MRD). Antibiotic sensitivity or MIC's of bacterial strains isolated by the two techniques were compared. This comparison of the IC identified a subgroup of patients who developed recurrent antibiotic resistant biofilm-induced peritonitis and their peritoneal catheters were subsequently removed.

Adult↗
PubMed1991

Use of streptokinase or urokinase in recurrent CAPD peritonitis.

In patients undergoing CAPD treatment, removal of peritoneal catheters has become a standard practice after two or more episodes of recurrent peritonitis which are refractory to antibiotic treatment. Immediate replacement of peritoneal catheters is not always safe in the presence of active peritonitis. Temporary institution of hemodialysis treatment in some of these patients may also be impossible because of unstable hemodynamic states or loss of vascular access sites. Successful continuation of CAPD treatment in some of these patients has been reported by using intraperitoneal (IP) administration of fibrinolytic agents such as streptokinase or urokinase as an adjunctive therapy to antibiotic treatment and as an outpatient procedure. Although numbers of cases reported are few in the literature and controlled studies in large numbers of patients are lacking, these reports emphasize the safety of IP use of these agents without any major systemic adverse effects. The reports are reviewed here to provide some practical guidelines for safe use of these agents in selected patients with recurrent CAPD-associated peritonitis.

Humans↗
PubMed1990

Pathogenesis of chronic bacterial prostatitis in an animal model.

A reproducible rat model of chronic bacterial prostatitis was developed using a defined bacterial pathogen (Escherichia coli) to study the pathogenesis and persistence of chronic bacterial prostatitis. The progression of inflammation and its consequences from acute to chronic prostatitis were documented with microbiological, histological, ultrastructural and immunological data. Chronic bacterial prostatitis in this model was associated with sparse glycocalix-enclosed protected bacterial microcolonies within the prostatic acini and ducts which appeared to stimulate a persistent local and systemic immunological reaction resulting in chronic inflammation of the gland. This model has many striking similarities to the natural history of human chronic bacterial prostatitis.

Animals↗
PubMed1990

Growth of bacterial biofilms on Tenckhoff catheter discs in vitro after simulated touch contamination of the Y-connecting set in continuous ambulatory peritoneal dialysis.

We simulated touch contamination of peritoneal dialysis fluids perfused through an in vitro system with a modified Robbins' device (MRD) and Y-connecting tubings, to study the pathogenesis of bacterial biofilm (BB) growth on Tenckhoff catheter (TC) discs. The spike ends of Y-connecting sets were dipped in a suspension of freshly cultured cells of Staphylococcus epidermidis (3 X 10(8) cfu/ml), and connected to 2 litres of 0.5% dianeal solution which was perfused through the MRD with plugs containing TC discs. Four simulated clinical exchanges were performed with or without prior flushing and/or bleach treatment of the Y sets. Control experiments were done with fresh Dianeal solution with no contamination, flushing, or bleach treatment. BB growth on the TC discs was examined by scanning electron microscopy (SEM) and transmission electron microscopy and quantitated by routine culture of scrapings from the discs. We noted that touch contamination of dialysis fluids via the spike ends of the connecting sets can generate dense BB growth on TC discs in this experimental system (62 +/- 8% by SEM and 10.2 +/- 8.3 X 10(3) cfu/ml by culture). This growth of BB was significantly reduced by flushing the Y set with sterile Dianeal solution (24.3 +/- 3% by SEM and 5.7 +/- 3.5 X 10(1) cfu/ml by culture) and was absent by bleach treatment. We conclude that although bleach treatment of Y sets can prevent BB growth, the 'flushing' procedure alone can significantly reduce BB growth on TC from touch contamination of dialysate fluid.

Bacterial Adhesion↗
PubMed1989

Peritonitis in peritoneal dialysis: bacterial colonization by biofilm spread along the catheter surface.

We have used modern techniques of direct microscopic examination and quantitative bacterial recovery to show the existence of a route of bacterial colonization along the external and internal surfaces of Tenckhoff catheters implanted in experimental animals. The external route of progressive bacterial colonization extends from the cutaneous exit site through the dacron cuff and into the peritoneum. Bacterial growth along this route consists primarily of glycocalyx enclosed bacterial biofilms adherent to catheter and tissue surfaces, and this surface colonization may or may not give rise to peritoneal infection in which free-living bacteria are found in the peritoneal fluid. The rate of this progressive bacterial colonization depends on the degree of bacterial contamination of the exit site at the time of implantation. Exit site sterilization (hibitane) delays the process while inoculation with rabbit skin strains of Staphylococcus epidermidis accelerates it. Even with optimal implantation techniques, bacterial colonization proceeds via this subcutaneous route so that most Tenckhoff catheter surfaces are covered with a bacterial biofilm, consisting predominantly of gram positive cocci, within three weeks after the implantation of these devices. The rate of bacterial biofilm development on both surfaces of these Tenckhoff catheters, the bacterial colonization of peritoneal tissues, and the dissemination of bacteria into the peritoneal fluid are all significantly accelerated by dialysis in this experimental animal model of continuous ambulatory peritoneal dialysis (CAPD).

Animals↗
PubMed1989

Significance of biofilm-adherent bacterial microcolonies on Tenckhoff catheters of CAPD patients.

The phenomenon of biofilm bacterial adherence to bioprosthetic devices and their relationship to various human infections are now well established. We have recently demonstrated that biofilm bacterial colonization of Tenckhoff catheters (TC) is very common in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) treatment. Based on our current work related to isolation of biofilm bacteria from peritoneal effluents of CAPD patients, we describe a novel way of diagnosis of this form of infection by using a modified Robbins device. Additionally, we describe the possible interaction of host defense factors with biofilm bacteria and ways to eliminate their colonization of TC for developing an overall strategy to prevent CAPD-associated peritonitis.

Bacteria↗
PubMed1988

An extracorporeal model of biofilm-adherent bacterial microcolony colonization for the study of peritonitis in continuous ambulatory peritoneal dialysis.

We have developed an extracorporeal system for investigating in vitro the biofilm-adherent bacterial microcolonies (BABM) that grow on Tenckhoff catheters (TC), to study peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD). A modified Robbins' device, attached to sampling plugs with TC discs and connected to the dialysate via a peristaltic pump, is run for 24 h; scrapings from pairs of TC discs are processed for assessment of viable BABM, one of each pair for culture by routine microbiology techniques and the other for examination by scanning and transmission electron microscopy (EM). No colonization was noted with fresh dialysis solutions and spent dialysates from patients without clinical peritonits; but, when bacterial suspensions were added to aliquots of the same dialysates, BABM were noted on both culture and EM. In a study of 4 patients on CAPD treatment, who had clinically evident peritonitis, routine cultures of spent dialysate were positive in only 2, but BABM were found in cultures and EM preparations of disc scrapings in all 4 cases. We conclude from these preliminary findings that this extracorporeal system is reliable, and well suited for studying the role of BABM in CAPD-associated peritonitis in vitro.

Bacterial Adhesion↗
PubMed1987

Combined evaluation of circulating immune complexes and antibodies to Pseudomonas aeruginosa as an immunologic profile in relation to pulmonary function in cystic fibrosis.

We developed a solid-phase radioimmunoassay with a reference standard pseudomonas antigen and used this with 125I-labeled anti-human immunoglobulin to evaluate specific antibodies to Pseudomonas aeruginosa, qualitatively and quantitatively, in sera from children with cystic fibrosis (CF) whose lungs were colonized by this bacterium. The results of this IgG assay correlated with the number of precipitin antibodies to the standard reference antigen determined by cross-immunoelectrophoresis in the same sera. Forced expiratory volume (FEV1; percentage predicted), determined as an indicator of lung injury in CF, was evaluated as an immunologic response to pseudomonas, against a profile derived from combined serial data on both the circulating immune complexes (CIC) and the Ps. aeruginosa antibodies (N = 25 CF patients; 108 sera). This revealed that in CF patients who had no specific IgG antibodies to Ps. aeruginosa and no IgG-CIC had the best pulmonary function (FEV1 = 115 +/- 14.52%) and those with high levels of antibodies to this organism and high IgG-CIC levels had the poorest lung function (FEV1 = 69.75 +/- 10.99%) (P less than 0.05). We believe that this indicates an immunologic basis for lung injury in cystic fibrosis.

Antibodies, Bacterial↗
PubMed1987

Prognostic implications of circulating immune complexes and Pseudomonas aeruginosa-specific antibodies in cystic fibrosis.

We re-examined the role of circulating immune complexes (CIC) in cystic fibrosis, by their serial measurement in 16 patients who had advanced lung disease and persistent specific antibodies to Pseudomonas aeruginosa in their serum. CIC were detected by 125I C1q-BA (IgG + IgM-IC) and Raji RIA (IgG-IC), and IgA-IC by a modification of the Raji RIA method. Serum precipitins to Ps. aeruginosa were detected by crossed-immunoelectrophoresis (XIE) and antibodies to alkaline protease (AP), elastase (EL) and exotoxin-A (EA) of Ps. aeruginosa were detected by ELISA technique. CIC were positive in greater than 50% of the samples in 8 patients (group A) and in less than 25% in the other 8 (group B); follow-up averaged 22 mo in group A and 26 mo in group B. The numbers of precipitins to Pseudomonas were equally high, and levels of antibodies to AP, EL, and EA of Ps. aeruginosa were similarly positive, in the 2 groups. In group A the CIC were mostly IgG-IC by Raji RIA (76%) and IgA-IC, whereas in group B C1q-binding IC (79%) and IgA-IC were more prevalent than IgG-IC by Raji RIA. Four group A children died during follow-up, together with one group B child in whom the CIC level had suddenly risen precipitously. We postulate that a high level of CIC in association with persistent specific-antibody response to Ps. aeruginosa heralds a poor prognosis in cystic fibrosis.

Adolescent↗
PubMed1986

Pericarditis and ulcerative colitis.

We report an 18-year-old man with a pericardial effusion complicating idiopathic ulcerative colitis. Circulating immune complexes were absent. He responded to sulfasalazine and prednisone, with resolution of the pericarditis and improvement in the symptoms of his inflammatory bowel disease (IBD). We recommend looking for pericardial effusion or pericarditis in patients with IBD and chest symptoms, and for IBD in obscure cases of these cardiac disorders.

Adolescent↗
PubMed1983

Myelin basic protein: a component of circulating immune complexes in multiple sclerosis.

Myelin basic protein (MBP) is an antigenic component of circulating immune complexes (CIC) in patients with multiple sclerosis (MS). Immune complexes were isolated from the sera by adsorption to Raji cells and then acid eluted. Final identification of MBP from Raji eluates was done by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by MBP radioimmunoassay (RIA) of gel eluates and by an immunoblot technique.

Antigen-Antibody Complex↗
PubMed1983

Absence of circulating immune complexes containing DNA in hemodialysed sera.

Although the presence of free DNA and antibodies to DNA in the sera of patients on maintenance hemodialysis has been reported, we found only a low incidence of antibodies to single-stranded DNA (ss-DNA) and native DNA (n-DNA) using an improved detection technique. In our search for evidence of the possible formation of DNA-anti-DNA circulating immune complexes (CIC), antibodies to n-DNA were detected in the sera of only 2 of 53 dialysed and 1 of 25 non-dialysed renal patients. CICs were detected in the sera of 17 of 53 dialysed (28% by Raji-RIA, 6% by Clq-BA) and 6 of 25 non-dialysed (20% by Raji-RIA and 24% by Clq-BA) renal patients: the difference is not significant (P greater than 0.25). DNase digestion of the dialysed sera that were positive for CIC by Raji-RIA produced no significant change in the results on re-assay (P greater than 0.50) in contrast with a significant decrease in CIC after DNase digestion of selected SLE sera and of solutions containing DNA-anti-DNA complexes formed in vitro (P less than 0.05). The formation of circulating DNA-anti-DNA complexes appears not to be the cause of the low incidence of antibodies to n-DNA in the sera of dialysed patients.

Antibodies↗
PubMed1982

Antibody-mediated cellular cytotoxicity against Raji cells ADCC(Raji): evaluation of false positives in the detection of circulating immune complexes by Raji-cell assay.

Raji-cell radioimmunoassay is a very sensitive and reproducible method for the detection of circulating immune complexes. Using a complement-independent, antibody-dependent cellular cytotoxicity assay against 51Cr-labeled Raji cells, there is no correlation between activity against Raji cells and positivity in Raji-cell radioimmunoassay for circulating immune complexes in three sets of sera (from renal transplantation patients, multiparous women, and patients suffering from systemic lupus erythematosus). We conclude that IgG antibodies to Raji membranes are not a significant cause of false-positive results in circulating immune complexes as detected by Raji-cell radioimmunoassay.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1982

Circulating immune complexes in multiple sclerosis: relation with disease activity.

Two hundred fifty-four MS patients were studied for circulating immune complexes (CIC) by three different assays: Raji-RIA, Clq-PEG, and Conglutinin-BA. Thirty-five percent of the sera were positive by one or more of these tests; Raji-RIA had the highest sensitivity (29.4%). Incidence of CIC in acute relapse, progressive, remission, and stable state of MS was 33.3%, 30.2%, 26.1%, and 23.1%, respectively, by Raji-RIA, compared with 7.75% and 8.82% among normal and neurologic controls. The incidence of CIC in neurologic controls differed significantly from both acute relapse and progressive disease, and almost significantly from patients in remission. There was no significant difference between patients with stable MS and neurologic controls, and there was no association of CIC with HLA-B7.

Adolescent↗