Biomedical subjects

M M Williams

Publications and source records attributed to M M Williams.

At least 37 records · Page 2Linked to original sources

PubMed1991

Regulation of interleukin-1 and tumour necrosis factor gene expression in myelomonocytic cell lines by 1,25-dihydroxyvitamin D3.

1,25-dihydroxyvitamin D3[1,25-(OH)2D3] is capable of regulating cells in the immune system and affects cytokine production by both T lymphocytes and by monocytes. We examined the effects of 1,25-(OH)2D3 on the regulation of interleukin-1 beta (IL-1 beta) and tumour necrosis factor-alpha (TNF-alpha) genes in HL-60 and U937 cells. 1,25-(OH)2D3 alone only induced low level expression of the genes for these cytokines. Phorbol 12-myristate 13-acetate (PMA) strongly induced the transcription of these genes, whilst the addition of 1,25-(OH)2D3 to PMA-stimulated cells caused a further dose-dependent synergistic increase in the mRNA for both cytokines in U937 cells. In PMA-stimulated HL-60 cells, 1,25-(OH)2D3 increased the mRNA for IL-1 beta but not that for TNA-alpha, These differences may be related to the different stage of myeloid differentiation in HL-60 and U937 cells.

Blotting, Northern↗

PubMed1990

Thoracic haemangiosarcoma in a 3-year-old horse.

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Animals↗

PubMed1989

Effects of a task-specific warm-up on anaerobic power.

Twenty-four untrained (UT) males (age 21 +/- 2.5 yr, height 1.77 +/- 0.05 m, weight 75.3 +/- 10.1 kg, values mean +/- SD) performed the Wingate Anaerobic Test (WT) under two conditions, cold (C) and following a warm-up (WU). Trials were separated by a minimum of 48 h. A modified Monark 818 cycle ergometer was interfaced with an Apple IIE microcomputer and peak power (PEAK), mean power (MEAN) and fatigue index (FI) determined. The WU trial consisted of an 8 min incremental continuous cycling bout (cadence 90 rev.min-1) with 5 min rest before the WT. During the C trial subjects completed only the WT. A repeated measures design was employed with order of trials counterbalanced. ANOVA revealed no significant differences for PEAK or MEAN between WU or C conditions. However FI was significantly greater (p less than 0.05) following the WU. A significant correlation (r = 0.45, p = 0.03) was obtained between WU intensity and FI. These findings suggest that our UT subjects were fatiguing themselves during the WU. Future studies are needed to assess whether a task-specific WU in which FI is not impaired would lead to improvements in PEAK and MEAN. Investigators should be aware that a self-spaced WU may increase FI in the WT in UT subjects.

Adult↗

PubMed1989

Early regulation of c-myc mRNA by 1,25-dihydroxyvitamin D3 in human myelomonocytic U937 cells.

The effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3; 10 nmol/l) on the human monomyelocytic cell line U937 were investigated. Addition of 1,25-(OH)2D3 led to a decrease in cell proliferation which fell at 72 h to 67.8 +/- 4.3% (mean +/- S.E.M.) of control values. The presence of CD14, a surface marker found on mature monocytes/macrophages but not on U937 cells, was detectable as early as 18 h and peaked at 48 h, when 63.6 +/- 4.2% of the cells were positive. However, changes in c-myc mRNA levels were detected earlier, starting within 4 h of exposure to the hormone and being reduced to 38 +/- 8.2% of control values of 24 h. These effects were reversible after removal of the hormone, with the same sequence of events seen following addition of the hormone. There was first an increase in c-myc mRNA levels, starting within 2 h and reaching control values by 24 h. These changes were followed by loss of CD14 which became undetectable after 72 h. Proliferation recovered slowly and incompletely, since it was 81.7 +/- 0.7% of control after 72 h. A constant reciprocal relationship between c-myc mRNA and CD14 levels was found both in the presence and after removal of 1,25-(OH)2D3. Regulation of U937 cell proliferation and maturation by 1,25-(OH)2D3 is thus preceded by early modulation of c-myc mRNA.

Blotting, Northern↗

PubMed1989

1,25-Dihydroxyvitamin D3, but not retinoic acid, induces the differentiation of U937 cells.

We have examined the effects of vitamin D3 metabolites and retinoic acid on the myelomonocyte cell line U937. Inhibition of proliferation, measured by incorporation of 125iodo-deoxyuridine was seen at 72 h with 1,25-(OH)2D3 but not 25(OH)D3 or 24, 25(OH)2D3 metabolites. CD14 molecules, not normally present on U937 cells, were induced on the cell surface. However, Class II major histocompatibility complex (MHC) molecules were not induced and Class I MHC molecules not increased in density as determined by flow cytometry. Retinoic acid inhibited proliferation but failed to induce CD14 molecules. These data suggest that both 1,25(OH)2D3 and retinoic acid act as an antiproliferation signal to U937 cells; only 1,25-(OH)2D3 induces the differentiation towards a more mature phenotype.

Calcitriol↗

PubMed1987

Upper extremity preservation before replantation.

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Amputation, Traumatic↗

PubMed1987

Relation of alveolar size to forced vital capacity in professional divers.

Eight cases have been studied in which both lung function and histological morphometric data was available on divers' lungs. A correlation was found between the increase in forced vital capacity measured at routine annual medical examination and the morphometric measurement of alveoli by mean cord length. The results suggest that reduction of forced expiratory volume in one second may be due to narrowing of small airways by distention of the alveoli.

Adult↗

PubMed1983

Ferredoxin from Aphanothece halophitica, a unicellular blue-green alga: close relationship to ferredoxins from filamentous blue-green algae and phylogenetic implications.

The amino acid sequence of a ferredoxin from a unicellular blue-green alga, Aphanothece halophitica, was established by the conventional methods. Total number of residues was 98 lacking only tryptophan. A most probable phylogenetic tree was constructed for 19 algal ferredoxins on the basis of an amino acid difference matrix made from the sequence comparison. A. halophitica has been classified as a unicellular blue-green alga in the same genus to which Aphanothece sacrum belongs, but the tree indicates A. halophitica ferredoxin to be very close to those of the members of filamentous blue-green algae. The tree divides prokaryotic and eukaryotic algal ferredoxins into several groups, suggesting that the ferredoxin phylogenetic tree reflects the evolutionary trails of various algae, which is also reflected in the structural characteristics, particularly in the presence of gaps. Other notable features are presented in considering algal taxonomy.

Amino Acid Sequence↗

PubMed1982

Amino acid sequence of Synechocystis 6714 ferredoxin: a unique structural feature of unicellular blue-green algal ferredoxin.

The amino acid sequence of ferredoxin from Synechocystis 6714, a unicellular blue-green alga, was determined by a combination of conventional methods. The ferredoxin was composed of 96 amino acid residues and lacked methionine and tryptophan. The sequence was as follows: Ala-Ser-Tyr-Thr-Val-Lys-Leu-Ile-Thr- Pro-Asp-Gly-Glu-Asn-Ser-Ile-Glu-Cys-Ser-Asp-Asp-Thr-Tyr-Ile-Leu-Asp-Ala-Ala- Glu-Glu-Ala-Gly-Leu-Asp-Leu-Pro-Tyr-Ser-Cys-Arg-Ala-Gly-Ala-Cys-Ser-Thr-Cys- Ala-Gly-Lys-Ile-Thr-Ala-Gly-Ser-Val-Asp-Gln-Ser-Asp-Gln-Ser-Phe-Leu-Asp-Asp- Asp-Gln-Ile-Glu-Ala-Gly-Tyr-Val-Leu-Thr-Cys-Val-Ala-Tyr-Pro-Thr-Ser-Asp-Cys-Thr-Ile-Glu-Thr-His-Lys-Glu-Glu-Asp-Leu-Tyr. In an alignment of various ferredoxins with high homology from unicellular and filamentous blue-green algae, Synechocystis 6714 ferredoxin showed 4 gaps. Those between residues 9 and 10 and between residues 12 and 13 were unique for the ferredoxins from the unicellular algae Synechocystis 6714 and Aphanothece sacrum (ferredoxin I). Therefore, ferredoxins from unicellular algae were distinguishable from those of filamentous algae in terms of the presence of gaps. This feature appears to coincide with the phylogenetic division between the two types of blue-green algae.

Amino Acid Sequence↗

PubMed1980