PubMed HealthSearch

Biomedical subjects

L Lachman

Publications and source records attributed to L Lachman.

At least 19 recordsLinked to original sources

Cellular interactions in marrow-grafted patients. III. Normal interleukin 1 and defective interleukin 2 production in short-term patients and in those with chronic graft-versus-host disease.

Peripheral blood mononuclear leukocytes (cells of marrow donor origin) from 89 patients were collected at various times after allogeneic marrow transplantation, stimulated in vitro by phytohemagglutinin, and assayed for the production of interleukin 2 (IL-2). This was done by testing culture supernatants for their ability to induce proliferation of human lymphoblasts and/or IL-2-dependent cultured murine cytotoxic cells. Supernatants from cultures of patient cells were compared with those of marrow donor cells. Supernatants produced by cells from most short-term marrow recipients (30-101 days postgrafting), regardless of the presence or absence of acute graft-versus-host disease (GVHD), and those from most long-term patients with chronic GVHD (103-1932 days postgrafting) had significantly lower-than-normal IL-2 activity, whereas cells from most long-term marrow recipients without GVHD (353-1934 days postgrafting) had essentially normal IL-2 activity. Additionally, we tested the ability of monocytes from 35 marrow recipients to produce interleukin 1 (IL-1) in response to lipopolysaccharide as compared with monocytes from marrow donors or normal unrelated individuals. IL-1 activity in culture supernatants of patient cells, regardless of the time of testing after marrow grafting and the status of GVHD, was found not to differ from that in supernatants of normal cells. These findings suggest that impaired T cell functions seen in some (but not all) marrow recipients are probably not due to IL-1 but to IL-2 deficiency or to the mechanism that causes IL-2 deficiency.

Adolescent

Role of interleukin 1 in anti-immunoglobulin-induced B cell proliferation.

In this report we describe conditions for polyclonal activation of small numbers of highly purified mouse B lymphocytes. Three signals are required for induction of DNA synthesis by the particular subset of small B lymphocytes investigated: a signal delivered by antibodies specific for the IgM receptor expressed on the B cell membrane; a signal delivered by a T cell-derived factor (B cell growth factor [BCGF]); and a signal delivered by the macrophage-derived factor interleukin 1 (IL-1). The conclusion that IL-1 has B cell co-stimulator activity is based on the findings that highly purified preparations of mouse and human IL-1 have the capacity to cause proliferation in B cells treated with anti-IgM and BCGF. Such cultures show an absolute dependence on exogenously added IL-1 when 2-mercaptoethanol is omitted from the medium. BCGF and IL-1 each act in a non-antigen-specific, non-H-2-restricted, synergistic manner. Their requirement is not observed when B cells are cultured at high density, presumably reflecting accessory cell contamination and endogenous factor production under these conditions. The B cell activation induced by these three signals is restricted to proliferation without the production of antibody-forming cells.

Animals

GLC determination of warfarin in human plasma.

A specific and quantitative GLC method for warfarin in human plasma is described. The procedure uses papaverine as the internal standard and involves a dichloroethane extraction of the acidified specimen. The organic extract is evaporated, and the evaporated extract is dissolved in 50 microliter of chloroform. Aliquots of 2-3 microliter are injected into a gas chromatograph equipped with a flame-ionization detector. The sensitivity of the method is such that 0.3 microgram of intact warfarin can be detected in 1 ml of plasma. Statistical analyses indicate a recovery of 97.26 +/- 1.89% SD. The procedure was successfully applied to plasma drug level studies in humans.

Adult

Differential pulse polarographic determination of clorazepate monopotassium and dipotassium.

Polarographic investigation of clorazepate monopotassium and dipotassium showed two cathodic waves at about -1.28 and -1.66 v. The cathodic wave associated with clorazepate monopotassium or dipotassium at about -1.66 v was a pH-independent, diffusion-controlled wave. This wave was used to develop a specific stability-indicating procedure for clorazepate monopotassium and dipotassium in the presence of their degradation products, namely, nordiazepam, 2-amino-5-chlorobenzophenone, and glycine. The method involves a 10(-2) M LiOH-10(-1) M LiCl extraction of the active ingredient from the formulation, filtration, dilution with the same supporting electrolyte, and then use of the standard addition technique for drug quantitation in capsules. Typical fomulation excipients did not interfere with the analysis. Accuracy and precision of the procedure were 99.55 +/- 0.68%.

Anti-Anxiety Agents

Analysis of homatropine methylbromide dosage forms.

A stability-indicating method of analysis of homatropine methylbromide in pharmaceutical formulations was developed. This method is based on the formation of a picric acid-quaternary ammonium complex, which is adsorbed on acid-washed diatomaceous earth in alkaline media followed by on-column chloroform extraction. The picrate complex is measured spectrophotometrically at 365 nm. The method was selective for homatropine methylbromide in that there was no interference from its major hydrolytic decomposition products, tropinium methylbromide and mandelic acid.

Methods

Automated analysis of warfarin sodium tablets.

An automated procedure was developed for the determination of warfarin sodium by following the steps of the manual USP procedure. The automated procedure is applicable to single tablets and composites of 20 tablets at different tablet concentrations. Sensitivity, precision, accuracy, and reproducibility are equivalent to the manual USP procedure. Sensitivity was approximately 15 mug/ml, with a coefficient of variation of 0.711%.

Autoanalysis