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Biomedical subjects

D White

Publications and source records attributed to D White.

At least 253 records · Page 14Linked to original sources
PubMed1988

A randomized trial of maintenance versus no maintenance melphalan and prednisone in responding multiple myeloma patients.

In order to assess the role of maintenance melphalan and prednisone (MP) in responding multiple myeloma patients, 185 eligible patients who responded to initial MP with stabilization for at least 4 months were randomized to either stop treatment and resume therapy at relapse or to continue MP until relapse. Time to first relapse was significantly shorter in the no maintenance group (P = 0.0011), however 57% of the no maintenance patients had a second response when MP was restarted and others had minor improvement. The time to final progression on MP, which reflects the duration of disease control by MP, was therefore longer for the no maintenance group (median = 39 months) compared to the maintenance group (median = 31 months) although the observed difference was not statistically significant (P = 0.086). Median survival from start of MP in the maintenance group (46 months) was also not significantly different than the no maintenance group (51 months) (P = 0.587). Multifactor analysis of the randomized patients demonstrated shorter total remission duration and shorter survival in patients who had an initially rapid response to therapy or a lesser reduction in serum M-protein concentration.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1987

Bull sperm 19S dynein polymerizes brain tubulin into microtubules.

Crude dynein extracted from bull sperm flagella polymerized pure phosphocellulose tubulin isolated from brain tissues into microtubules. This effect was predominantly due to the 19S dynein particle in the extract. ATP stimulated up to five fold the polymerization of brain tubulin by bull sperm dynein. Hydrolysis of ATP was not required since vanadate at a concentration sufficient to block dynein ATPase activity did not interfere with ATP stimulation and because the non hydrolyzable ATP analogue adenylyl (beta-gamma-methylene) diphosphate (AMPPCP) had effects similar to those of ATP. These results suggest that, in addition to hydrolyzing ATP to generate the driving force necessary for microtubule sliding within the axoneme, dynein may also interact with ATP to polymerize tubulin into microtubules.

Adenosine Triphosphatases↗
PubMed1987

Structure and mass analysis of 12S and 19S dynein obtained from bull sperm flagella.

The Brookhaven scanning transmission electron microscope (STEM) was used to elucidate the structures and masses of 12S and 19S dynein extracted from bull sperm flagella. The 12S particle was a single globular particle with an average mass of 311 +/- 10 kdaltons. The 19S dynein particles consisted of two globular heads joined to a common base. The average mass of the 19S particle was 1.6 +/- 0.04 X 10(6) daltons. Thus, with the exception of the larger mass, the bull sperm 19S dynein molecule resembles the two-headed 21S dynein obtained from sea urchin sperm flagella and the 18S dynein obtained from Chlamydomonas with the possibility of a third head giving rise to the 12S particle. The structure, mass and polypeptide composition of bull sperm flagella dynein is compared with outer arm dyneins previously obtained from Chlamydomonas, Tetrahymena, and sea urchin sperm flagella.

Adenosine Triphosphatases↗
PubMed1987

Modulation of reflex and voluntary EMG activity in wrist flexors by stimulation of digital nerves in hemiplegic humans.

Changes in EMG activity in the wrist flexor muscles were studied in response to electrical stimulation of digital nerves and to sudden extension perturbations at the wrist produced by a torque motor in human subjects with unilateral cerebral hemisphere lesions. With the subjects maintaining a steady voluntary contraction against a constant load, digital nerve stimulation produced a series of excitatory and inhibitory changes in tonic EMG activity from the wrist flexors in both the normal and paretic arm. The most consistent response was a period of EMG inhibition beginning approximately 38 msec after the stimulus and lasting approximately 35 msec. With relatively weak electrical stimuli, there was less EMG inhibition in the paretic arm than in the normal arm; with stronger stimuli, the inhibitory response was similar in the two arms. The electrical stimuli and mechanical perturbations were then delivered together, with the interval between them adjusted so that the expected period of inhibition following electrical stimulation coincided with either the early (M1) or the long latency (M2) components of the stretch reflex. In the normal arm electrical stimulation produced more inhibition of the M2 component than of the M1 component. In the paretic arm, inhibition during the M2 component was less marked and similar in degree to that which occurred during M1. These results are compatible with the view that M1 and M2 are normally mediated by separate neural pathways. The long latency EMG activity evoked by muscle stretch in the paretic arm of hemiplegic patients may be generated by pathways or mechanisms different from those in the intact arm.

Electric Stimulation↗
PubMed1987

Expression of the non-T ALL-associated p24 antigen on leukaemic blasts from patients with ANLL.

Leukaemic cells from the peripheral blood of 90 patients with acute leukaemia (54 non-lymphocytic (ANLL) 36 lymphocytic (ALL)) have been examined for the presence of the platelet/ALL-associated p24 membrane antigen by indirect immunofluorescence and flow cytometry using monoclonal antibody FMC8. Cells from 28 of the ANLL patients and 24 of the ALL patients expressed the antigen. In many specimens, both ANLL and ALL, blast cell populations were heterogeneous with respect to FMC8 binding. In ANLL, FMC8-positive cells were observed in specimens from a range of morphological subtypes. Proteolytic stripping/resynthesis experiments demonstrated that the antigen was synthesized by ANLL cells, not passively acquired. Immunoprecipitation and electrophoretic analysis of the antigen from NP40 lysates of 125I surface labelled cells from a patient with acute monoblastic leukaemia confirmed that the epitope identified by FMC8 was present on a peptide of the same molecular weight (p24) as that observed on ALL cells.

Acute Disease↗