PubMed Health⌕ Search

Biomedical subjects

D Davidson

Publications and source records attributed to D Davidson.

At least 253 records · Page 14Linked to original sources
PubMed1977

Monoamine metabolites in cerebrospinal fluid in multiple sclerosis.

The concentrations of homovanillic acid (HVA), 5-hydroxyindolylacetic acid (5-HIAA), and 4-hydroxy, 3-methoxyphenylethylene glycol (MHPG) were estimated in the lumbar cerebrospinal fluid (CSF) of control subjects and in some patients who probably, and others who definitely, suffered from multiple sclerosis (MS). In the control group, the concentration of HVA was lower in people who underwent lumbar puncture having fasted and been recumbent for 12 hours before the procedure than in those from whom CSF was obtained under non-standardised conditions. These studies demonstrate that a standardised procedure for lumbar puncture is required in order to obtain meaningful results. In patients suffering from MS the CSF 5-HIAA concentrations were significantly lower than in comparable controls but the HVA concentrations did not differ. There was no relationship between metabolite concentrations, site of lesion, the duration of the disease, gamma-globulin levels nor the occurrence of relapse within the previous month.

Female↗
PubMed1977

Relationship between nuclear morphology and the phases of the cell cycle during cercarial development of the digenetic trematode Trichobilharzia ocellata.

During the proliferative phase of cercarial development in the digenetic trematode Trichobilharzia ocellata, nuclei varied in size, appearance of the chromatin, and intensity of Feulgen staining. On the basis of interphase nuclear morphology six nuclear classes were identified. Data from microspectrophotometric determinations and 3H-TdR labeling experiments were used to correlate each kind of interphase nucleus with a phase of the cell cycle. Marked variability in nuclear area developed between cells by time they reached late G1. Increases in nuclear area could not be correlated with the onset of DNA synthesis. Throughout all stages of development of T. ocellata cercariae, proliferating cells divide mitotically; meiotic divisions were never seen. Thus, the mode of reproduction appears to be asexual. No evidence was found to support previous suggestions of diploid parthenogenesis.

Animals↗
PubMed1977

Cell cycle analysis in developing cercariae of Trichobilharzia ocellata (Trematoda: Schistosomatidae).

Cellular proliferation has been analyzed during cercarial development of the digenetic trematode Trichobilharzia ocellata. Prior to the tail-bud stage (about 1,000 cells), cells were actively involved in cellular proliferation. The mean cell cycle was 15.2 hr. The time for mitosis was 1.6 hr; for G1, 5.6 hr; for G2, 3.2 hr, and for the S phase, 4.8 hr. Beginning with the tail-bud stage, an increasing proportion of cells accumulate in the G1 phase. Cytological evidence of changes in the amount of cytoplasm per cell revealed that these noncycling cells were differentiating. During organ development and differentiation, the proportion of proliferating cells decreases and by the 2,000-celled stage proliferation ceases. Our results do not support a germinal lineage theory of cercarial development since none of the observed nuclear types could be unequivocally identified as belonging to the germ line.

Animals↗
PubMed1976

Lysosomal enzymes in cerebral atrophy.

In seven patients with cerebral atrophy due to pre-senile dementia and/or cerebrovascular disease, the activity of acid phosphatase in lumbar cerebrospinal fluid (CSF) was higher (p less than 0.05) than in six controls. The activity of arylsulphatase and beta-galactosidase in CSF was the same in the two groups. In the serum, the activities of acid phosphatase and arylsulphatase were the same in the two groups but the activity of beta-galactosidase was lower (p less than 0.02) in patients with cerebral atrophy.

Acid Phosphatase↗
PubMed1975

The freezing lesion. III. The effects of diphenylhydantoin on potassium transport within nerve terminals from the primary foci.

Possible mechanisms by which dephenylhydantoin (DPH) controls seizures were examined. The effects of intraperitoneal DPH on seizure discharges within epileptogenic freeze lesions were correlated with DPH action on in vitro potassium uptake within synaptosomes isolated from the same freeze foci. When in vivo DPH suppressed seizure discharges, it stimulated in vitro potassium uptake within synaptosomes incubated in a high-Kplus (10 mM) media. With 2-5 mM Naplus and 10mM Kplus, DPH stimulation of synaptosome potassium uptake was reversed by ouabain. With 50 mM Naplus and 10 mM Kplus, DPH stimulation of potassium uptake was not reversed by ouabain. In low-Kplus (0.2-5 mM) media, DPH did not affect potassium uptake even when sodium concentrations were varied at 10-100 mM. In sham-operated controls and in non-epileptogenic lesions, the effects of DPH on synaptosome potassium uptake were identical to those previously reported in normal brains. These results strongly suggest that DPH controls the epileptogenic state by stimulating potassium uptake within synaptic terminals. DPH controls the epileptogenic state by stimulating potassium uptake within synaptic terminals. DPH enhances synaptic potassium uptake by stimulating the (Naplus-Kplus) pump and a second potassium uptake process which is insensitive to ouabain.

Animals↗