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Biomedical subjects

P Biswas

Publications and source records attributed to P Biswas.

63 records · Page 4Linked to original sources
PubMed1989

Role for T cells, IL-2 and IL-6 in the IL-4-dependent in vitro human IgE synthesis.

The role of T cells and monocytes, as well as that of cytokines, such as IL-1, IL-2 and IL-6, on the IL-4-dependent in vitro human IgE synthesis was investigated. Recombinant IL-4, IL-4-containing T-cell clone supernatants and different combinations of recombinant cytokines failed to induce highly purified B cells to synthesize IgE. IL-4-dependent IgE synthesis was restored by addition to purified B cells of either untreated or mitomycin C-treated autologous T lymphocytes. Addition to purified B cells of autologous monocytes did not restore the IgE response, but usually it exerted a potentiating effect on the synthesis of IgE induced by IL-4 in the presence of suboptimal concentrations of T cells. The activity of T cells apparently preceded that of IL-4 and required a physical contact with B cells. The presence in culture of IL-2 also appeared to be necessary for the T-cell and IL-4-dependent IgE synthesis. Even though not essential, IL-6 was able to potentiate IgE synthesis in most experiments, whereas IL-1 did not display any modulatory effect.

B-Lymphocytes↗
PubMedDate not supplied

Increased production of IgE protein and IgE antibodies specific for fungal antigens in patients with the acquired immunodeficiency syndrome.

Levels of IgE protein and IgE antibodies specific for 8 different allergenic extracts were measured in the serum of a large series of patients infected by the human immunodeficiency virus (HIV) and in HIV-seronegative subjects belonging to the same risk groups (intravenous drug-users, homosexual men and hemophiliacs). The proportion of subjects showing elevated IgE levels was higher among HIV-infected patients with group IV disease than among HIV-infected patients with group II-III diseases or seronegative individuals. In addition, many HIV-infected patients with elevated IgE levels showed the presence in their serum of IgE antibodies specific for fungal antigens.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

In vitro infection with HIV of antigen-specific T cell clones derived from HIV-seronegative individuals. Effects on cytokine production and helper function.

Three human T cell clones (TCC) specific for purified protein derivative of Mycobacterium tuberculosis were incubated in the presence of polybrene and phytohemagglutinin with irradiated mononuclear cells from one individual exhibiting seropositivity for human immunodeficiency virus (HIV) and high levels of circulating p24 antigen. After three weeks, TCC showed HIV integration in their DNA, as shown by polymerase chain reaction analysis and Southern blot technique. All the three HIV-infected TCC maintained their ability to recognize the specific antigen, even if their proliferative ability was reduced. The ability of the HIV-infected TCC to produce IL-2, IL-4 and IFN-gamma in response to phorbol myristate acetate plus anti-CD3 monoclonal antibody was decreased, whereas their ability to produce TNF-alpha was unaffected or even enhanced. Two out of the three HIV-infected TCC showed the ability to provide helper function for polyclonal immunoglobulin production when cocultured with autologous B cells in the absence of any stimulant. These data suggest that in vitro infection of normal human TCC may provide a useful model for the study of immunological alterations induced by HIV.

Clone Cells↗
PubMedDate not supplied

Mechanistic understanding of aerosol emissions from a brazing operation.

Welding operations produce gaseous and aerosol by-products that can have adverse health effects. A laboratory furnace study was conducted to aid understanding of the chemical and aerosol behavior of a widely used, self-fluxing brazing alloy (89% Cu, 6% Ag, 5% P) that is also used with a supplemental fluxing compound to prevent oxidation at the molten metal surface. The results indicate that the aerosols generated by the alloy are transient (produced over a short duration of time) and are associated with mass transfer of phosphorus species from the molten metal surface to the surrounding gas. In contrast, when the alloy was used in conjunction with the supplemental fluxing compound, a relatively nontransient, submicron-size aerosol was generated that was several orders of magnitude higher in concentration. Thermodynamic equilibrium analysis suggests that fluoride (a major constituent in the fluxing compound) played a significant role in reacting with the brazing alloy metals to form gas phase metal fluoride compounds that had high vapor pressures when compared with their elemental or oxide forms. As these metal-fluoride vapors cooled, submicron-size particles were formed mainly through nucleation and condensation growth processes. In addition, the equilibrium results revealed the potential formation of severe pulmonary irritants (HF and BF3) from heating the supplemental fluxing compound. These results demonstrated the importance of fluxing compounds in the formation of brazing fumes, and suggest that fluxing compounds could be selected that serve their metallurgical intention and suppress the formation of aerosols.

Aerosols↗
PubMedDate not supplied

Selective enrichment of CD30-expressing cells within the blast region of lymphocytes from patients with primary HIV infection (PHI).

Individuals experiencing a primary infection with HIV (PHI) are known to undergo a potent activation of their humoral and cellular immune response. We investigated the expression of CD30 in peripheral blood mononuclear cells (PBMC) from 15 PHI patients before their initiation of HAART, since elevated levels of its soluble form, sCD30, have been previously documented in the plasma/sera of PHI patients. We also analyzed other lymphocyte-associated activation markers, including CD69, CD25 and HLA-DR. When looking at total lymphocytes, HLA-DR was expressed on the majority of lymphocytes, followed evenly by CD69 and CD25, and last by CD30. Of note, we observed that 13 out of these 15 patients displayed a characteristic expansion of lymphocytes with larger morphology (termed blasts). When a morphologic gate was drawn on these blasts, the percentage of CD25-, CD69-positive cells remained substantially unchanged, that of HLA-DR-positive cells augmented, but the the most striking increase occurred in the percentage of CD30-expressing lymphocytes. Therefore, although all of the molecules studied are considered lymphocyte activation markers, CD30 is most likely to be expressed within cycling/proliferating cells of the lymphoblast fraction during the earliest phases of HIV infection.

Antigens, CD↗
PubMedDate not supplied

Role of interleukins in induction and regulation of human IgE.

The studies on human IgE synthesis here summarized provide further insight into the cellular and molecular mechanisms involved in IgE regulation, as well as in the alterations responsible for IgE disregulation in some pathological conditions. They have clearly demonstrated that IL-4 is the essential factor for the induction of human IgE synthesis, since no substantial IgE production in vitro could be obtained in the absence of this lymphokine. Another T cell-derived lymphokine, IFN gamma, negatively regulates the IgE synthesis induced by IL-4. These two lymphokines can be produced by different T helper cells, as shown in mice, but they can also be the product of the same T cell clones. In such a case, the possibility that a given clone provides helper function for IgE seems to be dependent on the balance between the amounts of the two lymphokines produced. The IgE helper activity of rIL-4 appeared to be dependent on the presence in culture of appropriate concentrations of T lymphocytes, suggesting that T-B cell contact or other interleukins, such as IL-2 and IL-6, are needed in IL-4-dependent IgE synthesis. Finally, alterations of one or more of these regulatory mechanisms may play a crucial role in the pathogenesis of diseases characterized by a hyperproduction of IgE.

Animals↗
PubMedDate not supplied

Long term follow-up of percutaneous transluminal renal angioplasty with special reference to aorto-arteritis.

Percutaneous transluminal renal angioplasty (PTRA) was attempted in 96 patients of renovascular hypertension (RVHT) admitted during the period 1986 to 1992. The patients' age ranged from 14-70 (mean: 38.7 +/- 18.8) years. There were 42 (43.8%) males and 54 (56.2%) females. The cause of renal artery stenosis (RAS) was aorto-arteritis in 44 (45.8%), atherosclerosis in 28 (29.2%) and fibromuscular dysplasia in 24 (25%). Bilateral RAS was found in 16 (16.7%). PTRA was angiographically successful in 92 (95.8%) patients. The mean pressure gradient decreased from 82.6 +/- 8.2 to 11.2 +/- 3.6 mm Hg in aorto-arteritis, 75.2 +/- 13.2 to 9.6 +/- 6.4 mm Hg in atherosclerosis and from 86.4 +/- 10.6 to 13.2 +/- 8.2 mm Hg in fibromuscular dysplasia respectively. The patients were followed up for 43.2 +/- 24.1 (range: 6-77) months. Remission or satisfactory lowering of blood pressure was achieved in 80 (86.9%) patients. Clinical success rate (remission or satisfactory lowering of BP) at the end of follow-up period was 75.3 percent. Randomly selected repeat angiography was done in 45 out of 92 (49.1%) patients at the end of 24 months of follow-up. Restenosis was detected in 12 (26.7%) patients and was commonest in the atherosclerotic group (42.8%), followed by fibromuscular dysplasia (14.3%) and least common in aorto-arteritis (11.8%). Repeat angioplasty was done successfully in 10 (83.3%) patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗