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Biomedical subjects

D Mason

Publications and source records attributed to D Mason.

At least 163 records · Page 9Linked to original sources
PubMed1982

Evaluation of platelet surface antigens: localization of the PlA1 alloantigen.

An approach is described for localizing antigenic determinants to specific platelet proteins. Platelets are solubilized, electrophoresed and transferred to nitrocellulose paper where they are immobilized. After incubation with radiolabelled specific antibody, the antigenic determinants are localized by radioautography. Purified proteins ranging in size from 50000 to 540000 could be studied in this manner and still retain their antigenicity. Solubilized immobilized platelet proteins were reacted with serum IgG from two patients with post-transfusion purpura known to have anti-PlA1 antibodies. The radioactivity was associated with a major protein band with an apparent molecular weight of 100000 daltons. However, when purified anti-PlA1 antibody eluted from PlA1 (+) platelets was used, at least six additional minor bands were noted with molecular weights ranging from about 86000 to 175000. No radioactive bands were noted using PlA1 negative platelets or reduced PlA1 (+) platelet proteins. Reaction of the antibody from one patient wih proteins from thrombasthenic platelets resulted in a marked reduction in the intensity of all radioactive bands. In addition, a new high molecular weight band was noted which was not present in reactions containing PlA1 (+) platelets. These data suggest that the PlA1 antigen is primarily but not entirely localized to glycoprotein IIIa. This approach is relatively simple, requires only minimal amounts of antibody and should be generally useful in the study of cellular antigens and other complex mixtures of proteins.

Antigens, Surface↗
PubMed1982

Analysis of T lymphocytes after bone marrow transplantation using monoclonal antibodies.

Using monoclonal antibodies to cell surface antigens and fluorescent cell sorter analysis, we studied peripheral blood lymphocyte subsets after bone marrow transplantation (BMT). In 13 patients studied 3 mo or more after BMT, the ratio of T-cell subsets defined by antibodies OKT4 and OKT8 was reversed (OKT4/OK%8 = 0.7 +/- 0.3) in comparison to normal volunteers or bone marrow donors (ratio OKT4/OKT8 = 1.7 +/- 0.4) (p less than 0.001). This reversed ratio persisted for up to 3 yr after BMT. In contrast to a previous report, presence of an abnormal ratio of T-cell subsets did not correlate with clinically significant graft-versus-host disease (GVHD). In agreement with a previous study, (26% +/- 8%; less than 4% in normals (p less than 0.001) and antibody OKT10 reactive cells (39% +/- 20% versus 10% +/- 4%) (p less than 0.01), suggesting in vivo activation. However, their PBL did not react with antibody B3/25 (antitransferrin receptor), a marker found on normal PBL after in vitro activation by mitogens (BMT patients less than 5%; normal PBL T cells plus PHA 45% +/- 11%). These results demonstrate that BMT patients have: (A) an abnormal ratio of T-cell subsets in the presence or absence of clinically significant GVDH disease so that these measurements were not useful in monitoring patients; (B) an increased number of T cells with cell surface phenotype (OKT8+, Ia+, OKT10+, B3/25-) that is distinct from normals but similar to patients with infectious mononucleosis or acquired hypogammaglobulinemia.

Acute Disease↗
PubMed1981

Effect of noise and reverberation on binaural and monaural word identification by subjects with various audiograms.

The Modified Rhyme Test (MRT) (Bell, Kreul, + Nixon, 1972; Kreul, Nixon, Kryter, Bell, Land, + Schubert, 1968) was used to test the word-identification ability of subjects with bilateral sensorineural hearing losses. The subjects were tested in a room with reverberation times, T, of .1 and .5 sec while listening monaurally, binaurally, aided, and unaided at various speech-to-noise ratios, S/N. A babble of 20 voices was used as a masker. Significant individual differences were found in a group of 15 subjects with various audiograms. The differences were not significant when a group was reduced to seven subjects with similar audiograms. The advantage of the binaural over monaural listening was significant and did not depend on reverberation or the use of hearing aids. Both the effects of S/N and T were significant. The effects on word-identification scores caused by a decrease in S/N from "quite" to +5 dB and by an increase in T from .1 sec to .5 sec were moderately correlated for individuals. There were individual differences in susceptibility to noise and reverberation, with subjects having asymmetrical audiograms being most susceptible. The analysis of consonant errors in noise or reverberation revealed no significant difference for the MRT. A significant difference emerged between consonant errors in the initial and final positions of the test words in both noise and reverberation.

Adult↗
PubMed1980

Imitation of suprasegmental patterns by five-year-old children with adequate and inadequate articulation.

Ten five-year-old children with adequate articulation skills and 10 five-year-old children with inadequate articulation skills were administered the Templin-Darley Test of Articulation and the Test of Rhythm and Intonation Patterns (TRIP). Differences between the adequate and inadequate groups in terms of the mean percentage correct and the correlations between TRIP and Templin-Darley Test scores within groups were statistically nonsignificant. Item analysis revealed no differences between groups in the pattern of performance on the three subtests of the TRIP or on specific test items. The possible effects of therapy enrollment on suprasegmental test performance are discussed, and future research needs are suggested.

Articulation Disorders↗
PubMed1980

The demonstration of antibody binding to platelet-associated antigens in patients with immune thrombocytopenic purpura.

Platelet destruction in chronic immune thrombocytopenic purpura (ITP) is due either to antibody against platelet-associated antigen(s) that attaches by the antigen-specific Fab portion of the molecule or to platelet-bound immune complexes that bind nonspecifically to a platelet Fc receptor. Since pepsin digestion destroys the Fc fragment, the effect of this agent on platelet binding should allow differentiation betwen these two mechanisms. Normal serum IgG, aggregated normal serum IgG, and IgG produced in culture by splenic cells from control subjects and ITP patients were radiolabeled and tested for platelet binding before and after pepsin digestion. The binding to target platelets of both aggregated IgG and IgG produced in culture by ITP cells was increased when compared to controls. However, F(ab)2 fragments from the ITP samples retained their binding ability while those from the aggregated IgG did not. We conclude that these ITP patients produced antibody specific for platelet-associated antigens.

Antigens↗
PubMed1980

An influence of binaural hearing aids on positioning of sound images.

An influence of binaural hearing aids on positioning of sound images produced by signals from two loudspeakers was investigated with normally hearing and hearing-impaired subjects. The image can be positioned along a horizontal line connecting the centers of the sources by adjusting the relative sound pressure levels of signals. When the listener is a symmetrical receiver, the image appears on the midline (0 degrees azimuth) for equal levels or away from the midline for unequal levels. Any asymmetry of the receiver causes a shift of the image away from the midline. In the study, the level differences, delta Ls, necessary to position sound images at 0 and +/- 12 degrees azimuths were measured. The baseline data were collected for 10 normally hearing subjects in unaided and aided conditions. In the aided conditions binaural aids were balanced (equal gains) or unbalanced (10 dB disparity in gains). The normally hearing subjects positioned the image on the midline with a group mean delta L of 0 dB in both unaided and balanced aided conditions. To position the image at +12 or -12 degrees azimuth they needed mean delta Ls that could be predicted from a theoretical equation. With unbalanced aids, a group mean delta L of +3 or -3 dB was needed for the midline image. The delta Ls for the side images also were shifted. For 12 hearing-impaired subjects with bilateral lossses, the midline delta Ls in unaided condition were within the normal range (+/- 2 dB). For two monaural hearing aid users with long experience, the midline delta Ls were greater than normal. The delta Ls for the side images were equal to or greatr than delta Ls for normally hearing subjects. In aided balanced and/or unbalanced conditions, some hearing-impaired subjects needed delta Ls for the midline image outside the normal range, and some could not position the image at the side azimuths. It was concluded that the binaural hearing aids can be a source of receiver asymmetry.

Adult↗
PubMed1979

Myelolipoma in a heterotopic adrenal gland: light and electron microscopic findings.

A symptomatic myelolipoma of the heterotopic adrenal gland was diagnosed as the cause of nephrotic syndrome and was surgically removed. Remission of the nephrotic syndrome promptly ensued. Ultrastructurally, the tumor consisted of well-differentiated cells resembling adrenal cortical cells, bone marrow cells in various stages of differentiation, and lipid cells. Some cells that contained fat were of adrenal cortical origin, but the derivation of most lipid cells and of bone marrow elements could not be deduced from the present ultrastructural findings.

Adrenal Gland Neoplasms↗
PubMed1979

Efficient interaction for automated chromosome analysis using asynchronous parallel processes.

It is likely that any practical automated chromosome analysis system will be interactive. To prevent long pauses in the stream of operator interactions, it is necessary, if using standard computer hardware, to configure for asynchronous and parallel operation. A system is presented which uses several computer processors, which can support one or more operators, and which divides processing into interactive and noninteractive sections, smoothes the rate of presentation of interactions, and keeps both the operator and the computer fully employed.

Chromosomes, Human↗
PubMed1975

Meningeal mycosis fungoides: clinical and cellular characteristics.

A patient with mycosis fungoides developed meningeal disease while his skin disease was in remission with systemic chemotherapy. His central nervous system involvement with mycosis fungoides was controlled with intrathecal methotrexate for 7 months. The proliferating cells recovered from the spinal fluid showed similarities to the Sézary cell by light and electron microscopy. Surface receptor sutudies suggested that these cells were lymphoid cells of thymic derivation. Although mycosis fungoides has been shown to spread to the central nervous system in autopsied cases, reports of clinical neurologic disease are rare, and in only one earlier report have malignant cells have been found in the spinal fluid. Thus, as in other lymphoproliferative disorders, prompt consideration of meningeal involvement in a patient exhibiting neurologic symptoms while in peripheral remission may allow earlier treatment of this complication.

Animals↗