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Biomedical subjects

R H Smith

Publications and source records attributed to R H Smith.

At least 163 records · Page 9Linked to original sources
PubMed1978

Measurement of chloroprocaine and procaine in plasma by flame ionization gas-liquid chromatography.

We describe an isothermal gas-liquid chromatographic procedure developed for measuring procaine and chloroprocaine in plasma. The unchanged drug is extracted into toluene from alkalinized plasma, together with an internal standard. The solvent is removed, the residue redissolved in methanol, and aliquots are injected into a 91.5-cm gas-liquid chromatographic column containing 3% OV-210. Sensitivity of detection is in the nanogram range.

Flame Ionization↗
PubMed1977

Defined conditions for the initiation and growth of cotton callus in vitro. I. Gossypium arboreum.

Defined in vitro conditions for callus initiation by Gossypium arboreum L. were determined, and different tissues were evaluated as explant sources, Environmental conditions tested included light versus dark, and low light versus high light. Different nutrient media as well as carbohydrate sources were examined. Our data show that hypocotyl tissue was superior to cotyledon or leaf tissue as the explant source for callus proliferation; the Murashige-Skoog inorganic formulation with (in mg per 1) 100 myo-inositol, 0.4 thiamine-HCl, 2 indoleacetic acid (IAA), 1 kinetin, and 3% glucose solidifield by agar was the best medium to initiate callus. Cultures with sucrose as a carbohydrate source browned rapidly. Callus proliferation was superior under high light (8000 to 9000 lux) conditions at 20 +/- 1 degree C. Various combinations of auxins and cytokinins were tested for their ability to improve callus proliferation and subsequent growth of subcultures. Although the MS medium containing IAA and kinetin was found superior for obtaining rapid proliferation of callus from hypocotyl explants, a second medium containing 2 mg per 1 naphthaleneacetic acid (NAA) and 0.5 to 1 mg per 1 benzyladenine (BA) was found necessary for vigorous growth of subcultured callus. A MS medium with 5 to 10 mg per 1 N6-[delta2-isopentenyl]-adenine (2ip) and 1 mg per 1 NAA was also favorable for continued subculturing.

Ascorbic Acid↗
PubMed1977

False-positive cytological diagnosis of lung carcinoma in patients with pulmonary infarcts.

Cytological examination of specimens obtained from the tracheobronchial tree has become an integral part of the evaluation of pulmonary lesions. Cytological criteria for the diagnosis of carcinoma exist and are well defined. Certain benign processes, however, may possess features strongly suggestive of carcinoma of the lung. We report 3 patients in whom a positive cytological diagnosis of carcinoma of the lung was made by an experienced cytopathologist. At operation each patient was found to have pulmonary infarct and no evidence of carcinoma. Review of this experience has disclosed cytological and clinical features that should alert the clinician to the possibility that the cytological diagnosis of lung cancer may be misleading in certain nonmalignant diseases.

Adenocarcinoma↗
PubMed1977

Some effects of variation in carbohydrate and nitrogen intakes on the chemical composition of mixed rumen bacteria from young steers.

1. Samples of rumen digesta were taken at different times after giving calves various dried forage or hay and cereal diets and mixed bacteria were separated. 2. For calves receiving dried forage only, the carbohydrate content of mixed bacteria varied with time after feeding, reaching a maximum of approximately 140 g/kg dry matter (DM) after 0-5-1h, decreasing to about 60 g/kg DM after 4 h. 3. Replacement of part of the dried forage with glucose to give a similar metabolizable energy intake but approximately half as much nitrogen, produced a similar pattern of change with time after feeding but resulted in a markedly increased maximum bacterial carbohydrate content (approximately 230 g/kg DM). Addition of urea to this diet reduced the bacterial accumulation of carbohydrate to approximately the same level as was found in samples from calves receiving forage only diets. For the forage diets the carbohydrate content fell to 60-100 g/kg DM 4 h after feeding. For the hay and cereal diet the value was 170 g/kg DM at this time. 4. Changes in bacterial carbohydrate content were largely a result of changes in storage polysaccharide (alpha-dextran) content. 5. Crude protein (N X 6-25) and ash contents of mixed bacteria decreased after feeding with all-forage diets, but returned to approximately fasting levels within 4 h. At this time samples from calves receiving dried forage and glucose diets contained less CP and more ash (approximately 450 and 220 g/kg DM respectively) than those from calves given diets of dried forage only (approximately 525 and 180 g/kg DM respectively). 6. CP, total carbohydrate and ash content of mixed rumen bacteria contributed approximately 0-80 g/g DM. 7. Sodium, potassium, calcium, magnesium and phosphate accounted for approximately 0-50 g/g bacterial ash.

Animals↗
PubMed1977

Degradation of the nucleic acids in mixed rumen bacteria on incubation with different media.

1. Mixed rumen bacteria were grown in vitro in a medium containing [U-14C]adenine. Radioactivity was incorporated into the purine bases of the nucleic acids. 2. Labelled bacteria were incubated with a nitrogen-deficient cell-free medium (medium A), a protozoa-free supernatant suspension from a slow-speed centrifuging of a steer's rumen contents (medium B) and whole rumen contents of a steer (medium C). Mean (six experiments) proportional rates of release of radioactivity (/h) were significantly greater for medium A (0-140) than for media B or C (0-055 and 0-43 respectively). Some of the radioactivity accumulated in the cell-free media; some was lost, partially as carbon dioxide. 3. Calculation from this and other information indicated that about 30% of bacterial nucleic acids may turn over in the rumen even in the absence of protozoa.

Adenine↗
PubMed1977

Digestibilities of nitrogen compounds in rumen bacteria and in other components of digesta in the small intestine of the young steer.

1. Mixed bacteria were obtained from the rumen contents of steers and were taken at different times after the animals had been given different feeds. The feeds contained [15N]urea and in some experiments Na2 35SO4 so that the bacteria were labelled with these isotopes. 2. Samples of labelled bacteria were subjected to a simulated abomasal digestion with pepsin and the digests were infused with a non-absorbed marker, polyethylene glycol, into the duodenums of test steers equipped with re-entrant ileal cannulas. Except for samples taken after a 24 h fast, which sometimes gave somewhat lower values, mean values for digestibilities of 15N and 35S in the small intestine were 0-79 and 0-85 respectively. 3. The corresponding value for the digestibility of 15N in similarly-treated wheat-leaf protein concentrate was 0-86. 4. Net digestibilities of total N in the small intestine of the test steers when they were given either a mainly protein-free diet of straw, tapioca and urea or a diet of flaked maize and hay were approximately 0-62. 5. From these and other values it was calculated that approximately 5-2 g intestinally-secreted endogenous N/d flowed through the ileum of a 100 kg steer.

Animals↗
PubMed1977

Measurement of thiamylal and thiopental in plasma by electron capture and flame photometric gas-liquid chromatography.

We describe an isothermal gas-liquid chromatographic procedure developed for measuring thiamylal and thiopental in plasma. The unchanged drug is extracted into ethyl acetate from acidified plasma, together with an internal standard. The solvent is removed, the residue methylated, aliquots, diluted with benzene, are injected into a 183-cm gas-liquid chromatographic column containing 3% OV-17. Sensitivity of detection is in the nanogram to picogram range.

Chromatography, Gas↗