Search PubMed⌕ Search

Biomedical subjects

G Majumdar

Publications and source records attributed to G Majumdar.

At least 19 recordsLinked to original sources
PubMed2005

Solid-state storage of Ag nanoparticles in anion exchange resin beads and their recovery.

This paper reports the idea and describes a method of reversible storage and recovery of silver nanoparticles (NPs) in anion exchange resin beads based on the principle of ion exchange. We also report that similar exchange of NPs was not possible with cation exchange resins. The Ag NPs were stored by simple exchange of anions of the resins, which were activated with OH- and NO3- ions. FTIR spectroscopic measurements support that the Ag NPs were exchanged with NO3- ions in the resins. The so-stored NPs could be regenerated by addition of NaBH4 solution to the resins. These NPs were recovered and subsequently utilized for catalytic reduction of an organic dye (eosin). Powder X-ray diffraction (XRD) pattern indicated storage of the NPs in the form of various oxides of silver in the resin, with the peak value of intensity corresponding to XRD of the NPs not changing with time. Scanning electron microscopic measurements show that the NPs in the beads were stable for over a month without the formation of any apparent agglomeration.

Journal Article↗
PubMed1998

Chronic lymphocytic leukaemia with cerebral infiltration.

Central nervous system (CNS) involvement is an extremely rare complication of chronic lymphocytic leukaemia (CLL). This report describes a case of stable, early stage CLL who developed histologically documented cerebral infiltration two years after the diagnosis and responded to cranial radiotherapy.

Central Nervous System↗
PubMed1997

Massive bone marrow necrosis as the presenting feature in a case of primary bone marrow high grade non-Hodgkin's lymphoma.

Massive bone marrow necrosis (MBMN) is a rare complication of non-Hodgkin's lymphoma (NHL) and usually occurs in the late stage of the disease. Primary bone marrow NHL with no evidence of disease elsewhere in the lymphoreticular system is also rare. Here a case of primary bone marrow high grade NHL is reported who presented with MBMN without any evidence of nodal or other extra-nodal disease.

Adult↗
PubMed1997

Thromboprophylaxis with low molecular weight heparin (Fragmin) in high risk pregnancies.

Venous thromboembolic disease remains the commonest cause of maternal death. The management of thromboprophylaxis in high risk women during pregnancy is contentious. Low molecular weight heparins (LMW) have theoretical advantages compared with unfractionated heparin and warfarin but have been poorly studied in pregnancy. We report on the use of LMW heparin (Fragmin) as thromboprophylaxis in thirty four high risk pregnancies. All the women had a previous thrombosis or a thrombosis in their current pregnancy +/- a recognised thrombophilic state (eleven had the antiphospholipid syndrome). Fragmin was given subcutaneously to maintain trough anti-Xa activity of 0.15-0.2 U/ml and 2 h post injection levels of 0.4-0.6 U/ml. The levels were checked monthly during pregnancy. Most women required 5,000U Fragmin once daily during the first trimester unless they were greater than 100 kg at the start of pregnancy. The mean time for dosage increase was 20.5 week (S.D. 8.2). 26/34 pregnancies (76%) required 5,000 twice daily at the end of pregnancy. Epidural anaesthesia was managed by omitting Fragmin dose or inserting the needle 6 hours after the previous Fragmin injection. There were no thromboembolic events thrombocytopenias or excessive haemorrhage. One woman had osteoporotic vertebral collapse post partum, she had no other risk factors for osteoporosis. LWM heparin (Fragmin) appears to be efficacious in preventing recurrent thromboembolic disease in pregnant women at high risk, but it is notable that osteoporotic fractures occurred post partum in one woman. Further trials are required to determine optimal dosage and safety.

Adult↗
PubMed1996

Idiopathic chronic DIC controlled with low-molecular-weight heparin.

Chronic disseminated intravascular coagulation (DIC) is a rare coagulation problem usually associated with malignant diseases. The present report concerns a patient with chronic immune thrombocytopenic purpura (ITP) who developed chronic DIC which responded to low-molecular-weight heparin (LMWH) therapy.

Aged↗
PubMed1996

Marked bone marrow eosinophilia at the time of relapse of acute myeloblastic leukaemia in association with the appearance of translocation t(12;20)(q24;q11).

We report a case of acute myeloblastic leukaemia (AML), FAB type M2, with karyotype t(8;21)(q22;q22), who at the time of relapse showed marked eosinophilia of the bone marrow. Karyotype analysis showed the appearance of an additional clone t(8;21)(q22;q22),t(12;20)(q24;q11). To the best of our knowledge, marked eosinophilia has not been reported in association with this particular chromosomal translocation.

Adult↗
PubMed1996

Spontaneous splenic rupture in uncomplicated multiple myeloma.

We report a case of spontaneous splenic rupture due to myelomatous infiltration of the spleen without any evidence of amyloidosis or any other complicating factors. A computer search of Medline since 1966 did not reveal any previously reported case of spontaneous splenic rupture in uncomplicated myeloma.

Bone Marrow↗
PubMed1995

Unremitting severe autoimmune haemolytic anaemia as a presenting feature of Hodgkin's disease with minimum tumour load.

Two patients are reported who presented with severe autoimmune haemolytic anaemia (AIHA) of warm antibody type, with poor response to treatment. Extensive investigations failed to find a cause in both cases. In one case therapeutic splenectomy, one year after the initial presentation, showed Hodgkin's disease (HD) in the spleen but nowhere else. The second patient died of unremitting AIHA almost two years after the presentation and HD was found in only one mediastinal lymphnode at autopsy. These cases illustrate that a minimum tumour load of HD undetectable by the usual investigations can be associated with life-threatening AIHA.

Adult↗
PubMed1995

Flow cytometry provides rapid and highly accurate detection of antisperm antibodies.

OBJECTIVE: Immunobead testing (IBT), the current standard for antisperm antibody detection, is time consuming and somewhat subjective. To overcome these limitations and maintain accuracy, we studied an immunofluorescent assay using flow cytometry. DESIGN: A validation study comparing flow cytometry to IBT in the detection of serum antisperm antibodies. SETTING: Flow cytometry laboratory. PATIENTS: Sera from 37 men after vasectomy (test) and sera from 35 fertile men (control). MAIN OUTCOME MEASURE: Test serum with and without immunoglobulin (Ig)G, IgA, and IgM antisperm antibodies as defined by IBT were analyzed by flow cytometry. Sensitivity and specificity of flow cytometry was calculated by defining the IBT as the true result. RESULTS: Flow cytometry identified 22 of 22 sera that were IgG positive (100% sensitivity), 12 of 14 sera that were IgA positive (86% sensitivity), and 4 of 4 sera that were IgM positive (100% sensitivity). Overall, 22 of 37 men were positive for antisperm antibodies. The flow cytometry correctly identified 71 of 71 negative sera (100% specificity). Fluorescence intensity values from the 37 study patients significantly correlated with immunobead binding to the head region and to the entire (more than one) region. CONCLUSIONS: Detection of IgG, IgA, and IgM antisperm antibodies by flow cytometry is highly sensitive and specific. In addition, flow cytometry is able to assess thousands of sperm rapidly and accurately, reducing sampling error and technical time.

Antibodies↗
PubMed1994

T lymphocyte subpopulations in patients with B-cell chronic lymphocyte leukaemia: relationship to infective episodes.

Patients with B-cell chronic lymphocytic leukaemia (B-CLL) have an increased susceptibility to infection. Quantitative abnormalities of T-cells have been previously reported in B-CLL, although the relationship between such abnormalities and the incidence of infection still remains to be established. We therefore enumerated lymphocyte subpopulations in 22 patients with B-CLL grouped according to the number of infective episodes in the previous three years. No significant differences were found between the patient groups and the mean number of T-cells subsets (helper, suppressor, suppressor-inducer and suppressor effector) or NK cells, but patients with frequent infections were found to have significantly higher CD5+ B-cell counts. Thus, we confirm that T-cell subpopulations are numerically altered in patients with B-CLL, but found that such changes are not predictive of susceptibility to infection. Our results however suggest that the malignant B-cells may exhibit immunosuppressive activity.

Aged↗
PubMed1994

IgG subclass levels in patients with B cell chronic lymphocytic leukaemia.

Patients with B-cell chronic lymphocytic leukaemia (BCLL) have low levels of serum IgG. In order to determine if this is a pan IgG deficiency or a selective suppression of one or more IgG subclasses, levels of IgG 1, 2, 3 and 4 in nine BCLL patients were determined and compared to those of nine age and sex matched controls. No significant differences were found in the levels of IgG1 and IgG2, but the patients were found to have significantly lower levels of IgG3 (p < 0.05) and IgG4 (p < 0.05). Selective deficiencies of these isotypes may explain the particular pattern of infection seen in BCLL patients.

Aged↗
PubMed1994

Effect of splenectomy on HIV-related thrombocytopenia and progression of HIV infection in patients with severe haemophilia.

Between May 1983 and September 1991 eleven patients with severe haemophilia underwent splenectomy for HIV-related thrombocytopenia. The sustained complete remission rate (platelets > 100 x 10(9)/l) was 82% over a mean follow-up period of 54 months. The group was compared with 22 age-matched non-thrombocytopenic HIV seropositive haemophiliacs who had not undergone splenectomy. Both groups had equivalent use of factor concentrate and there was no significant difference between the groups in terms of anti-retroviral treatment. Analysis of clinical progression of HIV infection and CD4 positive lymphocyte (CD4+) counts, for the time since splenectomy, revealed no significant difference in progression of HIV infection in the splenectomized group compared with the control group. It is concluded that splenectomy is an effective treatment for HIV-related thrombocytopenia and has no adverse effect on the progression of HIV infection.

CD4-Positive T-Lymphocytes↗
PubMed1993

Heparin-induced skin reaction due to two different preparations of low molecular weight heparin (LMWH)

Heparin-induced skin reaction is a recognized complication of subcutaneously administered, unfractionated heparin, and has recently been described in association with the use of two LMWH preparations, Fragmin and Fraxiparin. We describe the case of a 25-year-old woman in whom characteristic skin lesions were induced on separate occasions by unfractionated heparin, Fragmin and a third preparation of LMWH, Clexane. This case demonstrates that substitution of one preparation of heparin for another does not prevent recurrence of skin reaction in susceptible patients. Alternative anticoagulants should be considered in these cases.

Adult↗
PubMed1993

Role of antigen-presenting cells in activation of human T cells by the streptococcal M protein superantigen: requirement for secreted and membrane-associated costimulatory factors.

The requirements for T-cell activation by the streptococcal superantigen (SAg), pepsin-extracted M protein from type 5 streptococci (pep M5), were studied by monitoring Ca2+ influx and cell proliferation. Cells from a pep M5-specific T-cell line showed no change in intracellular Ca2+ levels in response to pep M5 when added alone or with freshly isolated autologous antigen-presenting cells (APC). However, after being incubated with pep M5 overnight, the APC secreted soluble factors that together with pep M5 induced a marked increase in intracellular Ca2+ levels in pep M5-specific T cells or freshly isolated, purified T cells. Removal of the SAg from the overnight APC-derived supernatants resulted in loss of the Ca(2+)-mobilizing activity, which was restored within seconds of addition of SAg, suggesting that both the SAg and the soluble factors synergize to induce the Ca2+ influx. Induction of cell proliferation required additional signals inasmuch as the activated APC-derived supernatant failed to synergize with pep M5 to induce the proliferation of purified T cells and required the presence of phorbol myristate acetate for this activity. Metabolically inactive, fixed APC were impaired in their ability to present pep M5 to T cells. Presentation of pep M5 by fixed APC was, however, restored when the APC-derived soluble costimulatory factors were added to the culture. Our data suggest that pep M5-induced activation of T cells is dependent on APC-derived soluble factors and an APC membrane-associated costimulatory molecule(s). These interactions may be important in regulating the in vivo responses to M proteins, could contribute to the severity or progression of infections with Streptococcus pyogenes, and may influence the susceptibility of individuals to its associated nonsuppurative autoimmune sequelae.

Antigen-Presenting Cells↗