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Biomedical subjects

A Dean

Publications and source records attributed to A Dean.

At least 73 records · Page 4Linked to original sources
PubMed1990

Effects of social support from various sources on depression in elderly persons.

Although global measures of social support demonstrate significant effects on psychological and physical well-being, the differential significance of various support sources is largely unknown. The present study examines differences in the effects of functional expressive support by source on depressive symptoms. This approach is contrasted with network interaction studies of elderly persons, which do not measure functional support but do suggest that friends are distinctly significant. Spouse, friends, and adult children were found to rank in descending order of importance; relatives show no effect. Low support may have stronger effects than unavailability of sources. Effects of supports and stressors are not conditioned by age, sex, or widowhood. Implications of findings and further research needs are discussed.

Aged↗
PubMed1990

[Occult tumors of the parotid gland and facial paralysis. A diagnostic problem].

The facial palsy produced by a parotid tumour, could be misdiagnosed due to the absence of a palpable mass or other any signs in the computerized axial tomography or nuclear magnetic resonance. However there are data derived from the facial anatomy, course and clinical characteristics from the palsy that could make us thinking on the presence of a parotid tumour. The objective of this article is to present this characteristics, together with a serial of clinic cases which coursed in the beginning with a facial palsy and had problems in their diagnostic. It's also remarked the significance of the presence or not of perineural infiltration to the parotid tumours that will condition not only the prognosis but also the clinic course.

Aged↗
PubMed1989

Effect of transforming growth factor-beta 1 on proliferation and induction of hemoglobin accumulation in K-562 cells.

The effects of transforming growth factor-beta 1 (TGF-beta 1) on proliferation and hemoglobinization in K-562 cells, a human multipotential hematopoietic cell line, were studied. We found that TGF-beta 1 could induce hemoglobin accumulation in K-562 cells. Various clones were selected on the basis of the inducibility of hemoglobinization by TGF-beta 1. One high response clone (no. 1) and one low response clone (no. 8) were studied in detail. Hemoglobin accumulation peaked on day 5 of culture in the presence of TGF-beta 1 (0.5 ng/mL, 20 pmol/L), when 90% of clone 1 cells, 55% of parent line cells, and less than 10% of clone 8 cells contained hemoglobin. There was a concomitant reduction in proliferation of 60% for clone 1, 40% for the parent line, and 30% for the clone 8 on day 5 of culture. Quantitative analysis showed that the hemoglobin contents in clone 1 after 5-day induction by TGF-beta 1 and hemin were 1.0 pg/cell and 2.9 pg/cell, respectively. The hemoglobin induced by TGF-beta 1 showed the same electrophoretic characteristics as the hemoglobin induced by hemin. The expression of epsilon-globin mRNA was minimally detectable in control cells and was induced in both TGF-beta 1 and hemin treated cells. Other cytokines with potential effects on K-562 cell proliferation and differentiation were also studied. Interleukin-1, interleukin-3, interferon alpha, interferon gamma, and inhibin, tested as single agents, showed minimal effects on proliferation. None of these agents could induce hemoglobinization or inhibit the hemoglobinization induced by TGF-beta 1.

Cell Differentiation↗
PubMed1989

Measuring the communication of social support from adult children.

Further knowledge of the nature and significance of the relationships of elderly persons to their adult children requires the application of social support scales tapping the quality and content of their interactions. Scaling efforts must further address conceptual and operational specification, the differentiation of sources and dimensions of support, the objectification of self-report scales, and construct validity. Respondents to this survey are a community, stratified probability sample of adults aged 50 and older (N = 1,174). Measures employed include 2 items reflecting instrumental support and 17 items designed to tap Cobb's (1976) definition of expressive support as consisting of information that one is loved, esteemed, and embedded in a social relationship characterized by mutual caring and obligation. Factor analyses consistently discern one instrumental and three expressive dimensions of support: Caring and Concern, Social Integration, and Love and Affection. These subscales are differentially correlated with sociodemographic characteristics of the parents and adult children, as well as with depression and disability. Implications of these and other findings are discussed.

Adult↗
PubMed1987

Yeast nucleosomes allow thermal untwisting of DNA.

Thermal untwisting of DNA is suppressed in vitro in nucleosomes formed with chicken or monkey histones. In contrast, results obtained for the 2 micron plasmid in Saccharomyces cerevisiae are consistent with only 30% of the DNA being constrained from thermal untwisting in vivo. In this paper, we examine thermal untwisting of several plasmids in yeast cells, nuclei, and nuclear extracts. All show the same quantitative degree of thermal untwisting, indicating that this phenomenon is independent of DNA sequence. Highly purified yeast plasmid chromatin also shows a large degree of thermal untwisting, whereas circular chromatin reconstituted using chicken histones is restrained from thermal untwisting in yeast nuclear extracts. Thus, the difference in thermal untwisting between yeast chromatin and that assembled with chicken histones is most likely due to differences in the constituent histone proteins.

Animals↗
PubMed1987

An evaluation of the Coulter Counter Model T660.

An evaluation of a Coulter Counter Model T660 has been carried out. This instrument is a compact, fully automated, blood cell counter which measures WBC, RBC, Hb, haematocrit, MCV and platelet count on a 100 microliter sample of whole blood. The instrument was assessed during one month of regular use. One possible microbiological hazard was detected, which could be corrected by an instrument modification. No mechanical hazards were identified. The instrument as supplied produced some inaccurate WBCs; this malfunction appeared to be consequent on a design fault relating to the burn circuit of the white cell aperture and following instrument modification performance was considerably improved. Results produced were broadly comparable with those produced by a Coulter Counter Model S Plus IV. Precision was satisfactory. Deviations from linearity on dilution were not sufficient to be of practical importance. Carryover was satisfactorily low. Time-lapse of up to 48 h did not introduce inaccuracy of sufficient magnitude to be of practical importance. Throughout varied from 52 to 63 specimens/h. Following instrument modification the overall assessment was that the T660 was easy to operate, reliable, and clinically useful.

Blood Cell Count↗
PubMed1986

Permissible discontinuity region of the alpha-chain of hemoglobin: noncovalent interaction of heme and the complementary fragments alpha 1-30 and alpha 31-141.

Generation of a fragment-complementing system of the alpha-chain on limited proteolysis with Staphylococcus aureus V8 protease has been investigated. Digestion of the alpha-chain (0.4 mM) of hemoglobin with V8 protease in phosphate buffer at pH 6.0 and 37 degrees C is limited to the peptide bonds of Glu-23, Glu-27, Glu-30, and Asp-47. Gel filtration of a V8 protease digest of the alpha-chain on a Sephadex G-50 column did not release any heme to the low molecular weight region, though some peptides were released from the protein. The filtration studies revealed the presence of two heme-containing components in the digest, the major one eluting at the alpha-chain position and the minor one eluting slightly ahead of the alpha-chain position. Reversed-phase high-performance liquid chromatography and amino-terminal sequence analysis demonstrated that the component eluting at the alpha-chain position contains species generated by the noncovalent interactions of heme and the complementary fragments alpha 1-30 and alpha 31-141. In dilute solutions (0.04 mM) the V8 protease digestion occurred exclusively on the carboxyl side of Glu-30(alpha). This high selectivity was also observed at pH 4.0 and pH 7.8. The visible spectra and the ultraviolet circular dichroic spectra of the digest reflect the native-like structure of the noncovalent fragment system. The dissociation constant of alpha 1-30 appears to be in the range of 10(-8) M. In tetrameric hemoglobin A the peptide bond of Glu-30-Arg-31 of the alpha-chain is not accessible to V8 protease digestion.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1986

An evaluation of the Coulter Counter Model S880.

An evaluation of a Coulter Counter Model S880 has been carried out. Certain findings have been further evaluated on a second instrument. Several safety hazards have been identified which could be corrected by minor modifications of the instrument or the mode of operation. Precision was found to be generally satisfactory, though for the platelet count and the WBC it was sometimes worse than specified. Most parameters were not strictly linear on dilution but only for the MCV and the MCH was the deviation from linearity sufficient to be of practical importance. Carryover was satisfactory. Results were generally comparable with those of a Coulter Counter Model S Plus IV. Estimates on all parameters were satisfactory on blood samples stored up to 24 h at either 4 degrees C or room temperature; beyond 24 h inaccuracy was seen particularly in the WBC, platelet count and MCV. Throughput was 60 to 70 samples/h in the whole-blood mode. Start-up and shut-down times were acceptably short. The instrument was assessed as acceptable and clinically useful, although reliability was somewhat less than expectations.

Blood Cell Count↗
PubMed1985

Unique pattern of HTLV-III (AIDS-related) antigen recognition by sera from African children in Uganda (1972).

Of 75 sera collected in the West Nile district of Uganda over a 1-year period between 1972 and 1973, 50 (66%) had antibody reactivity to human T-cell lymphotropic virus subgroup III (HTLV-III) at low titer levels. Sera were initially screened by HTLV-III enzyme linked immunosorbent assay and sera with values less than normal mean + 2 SD were removed from testing. The remaining sera were tested for positivity by an amplified Western blotting procedure which incorporated a three-layer immunoperoxidase procedure. Immunoglobulin reactive with HTLV-III Mr 24,000, 41,000, and 76,000 proteins were present in nearly all positive sera. The antibody status of this group was unlike any normal or acquired immunodeficiency syndrome-risk group previously tested. The high prevalence and relatively low titers suggest the detection as early as 1972 of a relative or predecessor of HTLV-III or of HTLV-III itself but existing in a population acclimated to its presence. It further suggests a likely African origin of HTLV-III.

Acquired Immunodeficiency Syndrome↗