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Biomedical subjects

C Smith

Publications and source records attributed to C Smith.

At least 973 records · Page 54Linked to original sources
PubMed1982

Paradoxical sleep at selective times following training is necessary for learning.

Rats were trained in a two-way shuttle shock avoidance task, 20 trials per day for 5 consecutive days. In Experiment 1, groups were subjected to selective paradoxical sleep deprivation (PSD) for daily 4 hour periods. It was found that only PSD applied between 9-12 hours or 17-20 hours after the daily training sessions resulted in acquisition deficits. These vulnerable time periods coincided with polygraphically observed PS increases above normal levels following identical training procedures in previous studies. In Experiment 2, animals were only allowed PS during the 9-12 hour and 17-20 hour post training time "windows" observed in Experiment 1. For the remaining time each day, they were subjected to PSD. Acquisition was found to be unimpaired, despite this severe treatment. However, any other equivalent length PSD regime which overlapped with either of the time "windows" resulted in severe retardation of task acquisition. Results were believed to provide strong support for the sleep-learning hypothesis.

Animals↗
PubMed1982

Selectivity of proteinuria as determined by high pressure liquid chromatography.

The methods used for measurement of the selectivity of glomerular filtration are usually long and tedious. We report the use of protein HPLC for the determination of the selectivity index. When compared to the conventional procedure, this new approach gave 82% correlation. This method offers many advantages in clinical chemistry due to its rapidity, sensitivity and the objectivity of data analysis.

Chromatography, High Pressure Liquid↗
PubMed1982

Glycosaminoglycans produced by human synovial cell cultures.

Human synovial cells in culture are known to synthesize hyaluronic acid, but the production of sulfated glycosaminoglycans (GAG) has received less attention. Using 14C-glucosamine as a precursor, GAG content was studied in the medium, trypsin-solubilized pericellular layer, and cell residue fraction of cultured synovial cells derived from the synovial membranes of nonrheumatoid and rheumatoid joints. Over 90% of the total non-dialyzable counts appeared in the culture medium, for the most part in hyaluronic acid. The remaining nondialyzable counts were cell-associated, almost equally divided between the pericellular layer and cell residues. In these fractions, only part of the counts were in GAG susceptible to testicular hyaluronidase digestion, and GAG were significantly lower in the cell residue of the rheumatoid synovial cells compared to the nonrheumatoid cells. Analysis of the chondroitinase ABC and AC digestion products of these GAG indicated the presence of chondroitin-4 and -6 sulfates, and dermatan sulfate, but not heparan sulfate. Similar findings with respect to the identity of the GAG in nonrheumatoid and rheumatoid synovial cell culture media were obtained with 35SO4 as a precursor.

Arthritis, Rheumatoid↗
PubMed1982

1,25-dihydroxyvitamin D3-treated hypoparathyroidism: 35 patients years in 10 children.

Ten hormone-deficient hypoparathyroid children have been successfully treated with orally administered 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] within a dose range of 0.01--0.10 microgram/kg . day for a total of 35 patient yr. Resistance to 1,25-(OH)2D3 therapy was not observed. By monitoring the blood ionized calcium level (normal range, 4.05--5.14 mg/dl) at monthly intervals, 8 hypercalcemic and 10 hypocalcemic episodes were recognized during the entire treatment experience, though the patients were asymptomatic. In the former cases, cessation of treatment for 3 days resulted in normocalcemia; in the latter, half of the episodes were transient and related to intercurrent febrile illnesses. The remaining hypocalcemic occurrences responded to an increase in the dosage of 1,25-(OH)2D3. During 1,25-(OH)2D3 treatment, the mean ionized calcium level for individual patients ranged from 4.04--4.39 mg/dl. Urinary Ca excretion, expressed as a ratio of calcium to creatinine, ranged from 0.177--0.244. Twenty-four-hour mean levels of serum 1,25-(OH)2D did not correlate with the blood ionized calcium concentration in 4 patients who underwent sequential blood sampling every 1--2 h for a total of 59 time points (r = 0.05; P greater tha 0.10). To elucidate the temporal relationship between hormonal and mineral responses to exogenous PTH, we administered bovine PTH to four untreated hypoparathyroid children. Serum concentrations of PTH increased before the rise in ionized calcium, which in turn preceded the elevation in circulating 1,25-(OH)2D. This order was followed also in the fall in serum concentrations of these blood constituents to pre-PTH infusion values. These results indicate responsiveness of the l alpha-hydroxylase enzyme to exogenous PTH in hormone-deficient hypoparathyroid children.

Adolescent↗
PubMed1982

Glucose metabolism of Haemonchus contortus adults: effects of thiabendazole on susceptible versus resistant strain.

Analyses of the in vitro glucose metabolism of Haemonchus contortus adults have confirmed a complex series of end-products: ethanol, n-propanol, propionate, acetate, and CO2 as the major end-products of catabolism. No difference in end-product accumulation was seen between the cambendazole sensitive (BPL) and cambendazole resistant (CR) strains. Thiabendazole (5 mM) in vitro depressed ethanol, propanol, acetate, and propionate accumulation by approximately 42% in the BPL strain. However, in the resistant strain (CR), these end-product accumulations increased by 50% when the worms were exposed to drug in vitro and 80% when exposed in vivo. Resistance manifested by the CR strain appeared to be associated with the ability to increase its carbon flow in the presence of thiabendazole.

1-Propanol↗
PubMed1982

Membranous structures in pinealocytes of the Chinese hamster (Cricetulus griseus); are they annulate lamellae?

Pinealocyte ultrastructure in the normal and spontaneously diabetic Chinese hamster has been studied. A literature comparison shows it to be similar to the pineal of the Syrian hamster; however, the incidence of membranous structures is more frequent in the Chinese as compared with the Syrian hamster. Stacks of membranous structures were present in pinealocytes of all animals in this study and, therefore, appear to be regularly occurring organelles in the pineal of this species. There are analogies between these membranes and annulate lamellae; however, like annulate lamellae, their functional significance is unknown.

Animals↗
PubMed1982

Reducing back displacement in the powered reclining wheelchair.

The powered reclining wheelchair used by quadriplegic and other severely disabled people was studied to determine how the chair could be modified so that repeated recline would not produce shear forces that tend to cause the user to be relocated in the chair, limiting independent functioning. Three modifications of the chair were studied: a freely sliding back, a commercially available powered sliding seat, and 4-bar linkage to hinge the chair back. A counterbalanced, freely sliding back was constructed for testing and was instrumented to measure displacement of the person in the chair during recline. The curves of back displacement vs angle or recline were determined for a sample or 8 quadriplegic subjects. The sliding back mechanism was determined to be impractical for incorporation into current chair designs since it required a heavy, rigid back frame. The sliding seat was found to have limited value since it only slightly decreased the back motion during recline. However, the 4-bar linkage virtually eliminated relative motion between the person's back and the chair back, providing a mechanism for potentially resolving this problem both in new recliner design and for retrofit to existing reclining wheelchairs.

Equipment Design↗
PubMed1981

Enhanced neutral protease activity in proliferating rheumatoid synovial cells.

Proteolytic enzymes associated with rheumatoid synovial cells (RSC) have been implicated in the degradation of articular cartilage. Proteases have been measured in proliferating rheumatoid synovial cells (P-RSC), proliferating nonrheumatoid synovial cells (P-NSC), and their nonproliferating counterparts (NP-RSC and NP-NSC). The P-RSC and P-NSC exhibit enhanced total surface-associated plus secreted neutral protease activity, as compared with NP-RSC and NP-NSC. The P-RSC exhibited significantly higher protease activity in this category compared to P-NSC. The RSC also secreted higher levels of secreted proteases alone compared to NSC. The secreted protease activity alone was not related to the proliferative state of the cells. Extractable protease activity was measured in early-passaged and serially-passaged P-RSC, NP-RSC, P-NSC, and NP-NSC. Extractable cellular protease activity measured at pH ranges from 5.0 through 8.0 was not significantly different between P-RSC and NP-RSC or between P-NSC and NP-NSC. The RSC contained elevated extractable cellular protease activity measured at pH ranges from 5.0 through 8.0 compared to extracts from later-passaged cells. The neutral protease activity in the early-passaged RSC was also higher than that measured at pH 6.0 or 8.0. In synovial cells cellular protease activity was related to the proliferative state and the origin of the cells. The P-RSC exhibited the highest levels of surface associated plus secreted neutral protease activity. The RSC also possessed the highest levels of extractable protease activity compared to NSC.

Arthritis, Rheumatoid↗
PubMed1981

Comparison of radiotherapy alone and radiotherapy with chemotherapy using adriamycin and 5-fluorouracil in bronchogenic carcinoma.

Eighty-two patients with histologically confirmed lung cancer were randomly allocated to receive either radiotherapy alone (2400-3200 rads, depending upon cell type) or the same dose of radiotherapy followed by four cycles of adriamycin and 5-fluorouracil. Eighty-one patients were evaluated and for the group as a whole survival was better in the undifferentiated group assigned to receive adjuvant chemotherapy but survival in the patients with squamous tumours was not significantly prolonged. The chemotherapy was not unduly toxic.

Carcinoma, Bronchogenic↗
PubMed1981

Absence of seasonal variation in serum concentrations of 1,25-dihydroxyvitamin D despite a rise in 25-hydroxyvitamin D in summer.

The serum concentrations of the vitamin D metabolites 25-hydroxyvitamin D2 (25OHD2), 25-hydroxyvitamin D3 (25OHD3), and 1,25-dihydroxyvitamin D (calcitriol) have been measured in normal subjects whose ages varied from 18 months to 35 yr. Samples were obtained in all months of the year in order to assess the effects of season on serum concentration. During the months of April to September, 25OHD3 levels are higher than in the winter months. No seasonal variation in the 25OHD2 or calcitriol serum concentration was observed. Age-related differences in 25OHD2 and D3 concentrations did not exist. The levels of calcitriol are higher in adolescence and increase from 35 +/- 19 pg/ml (SD) at 1.5-10 yr of age to 54 +/- 21 pg/ml at 10-20 yr of age. In young adults, the levels fall again to 28 +/- 16 pg/ml. Accordingly, despite a seasonal variation in the precursor of calcitriol, the levels of this most active metabolite of vitamin D do not change in relation to sunlight exposure. This lack of seasonal variation is further evidence of the tight feedback regulation of calcitriol.

25-Hydroxyvitamin D 2↗