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Biomedical subjects

R Nelson

Publications and source records attributed to R Nelson.

At least 307 records · Page 17Linked to original sources
PubMed1979

"CAMP" combination chemotherapy for unresectable non-oat cell bronchogenic carcinoma.

Experience with camp chemotherapy of 84 unresectable non-oat cell lung cancer patients is described. Fourteen (27%) of 51 patients with measurable lesions responded (3 CR, 11 PR) for a median response duration of 5 months with a range of 1 to 19+ months. Median survival of responders was 370 days, but response was not independent of performance status. Survival of patients without measurable lesions was less favorable than that of even nonresponders, suggesting prediction of response to CAMP by site of metastasis. Preliminary results of a randomized prospective trial of the CAMP combination versus CCNU as a single agent for patients with good performance status fail to show a difference in survival.

Antineoplastic Agents↗
PubMed1978

Ferritin as an index of bone marrow iron stores.

We examined the relationship of serum ferritin to bone marrow iron stores in 73 anemic male medical inpatients with liver disease, alcoholism, chronic inflammatory disease, and malignancies. A correlation of r = 0.75 (P less than .00005) was found between serum ferritin and bone marrow iron stores (BMIS) for the entire group. Liver disease as manifested clinically or by increased levels of serum glutamic-oxaloacetic transaminase did not appear to significantly affect this relationship. Patients with folic acid deficiency did tend to have a disproportionate increase in ferritin in relation to BMIS, but this did not seem to destroy the usefulness of ferritin levels. A useful clinical rule seems to be that serum ferritin of greater than 100 ng/ml tends to exclude iron deficiency, and a level of less than 30 ng/ml tends to confirm decreased iron stores.

Alcoholism↗
PubMed1978

Intracellular staining reveals different levels of stratification for on- and off-center ganglion cells in cat retina.

1. Ganglion cells in the retina of the cat were stained by intracellular dye injection after recording their responses to photic stimulation. 2. All cells encountered were divided into those giving on-responses and those producing off-responses, and the level of dendritic branching of these two groups was compared. Cells giving off-responses were found to branch high in the inner plexiform layer (IPL), near the amacrine cell bodies (sublamina a); those giving on-responses were found to branch lower in the inner plexiform layer (sublamina b). 3. Dye-injected cells varied widely in morphology and size, having cell bodies ranging in diameter from 8 to 32 micrometer and dendritic fields ranging from 25 to 490 micrometer in diameter; yet the sign of the response of each unit correlated only with the level of dendritic branching. Thus, no other morphological feature except stratification appears to be important in determining the sign of the response of these cells. 4. The stratification of ganglion cells into on- and off-layers parallels the distribution of the axon terminals of the flat and invaginating cone bipolars. Flat cone bipolars are in a position to contact off-center ganglion cells (in sublamina a) and invaginating cone bipolars are in a position to contact on-center ganglion cells (in sublamina b). 5. The rod and cone inputs to some cells were characterized by comparing their responses to deep red and blue rod-matched stimuli over a 2-log unit range starting at dark-adapted threshold. About half the cells appeared to be rod dominated under these conditions, whereas the others appeared to have mixed rod and cone signals. 6. The nature of the rod and cone pathways to ganglion cells is discussed.

Animals↗
PubMed1977

Cat cones have rod input: a comparison of the response properties of cones and horizontal cell bodies in the retina of the cat.

The responses of horizontal cell bodies and cones in the retina of the cat have been studied by means of intracellular recording and Procion dye injection in an isolated, arterially perfused eyecup preparation. Comparison of the hyperpolarizing responses of these units to red and blue stimuli of different intensities indicated that all morphological varieties of horizontal cells and, additionally, cones themselves, had mixed rod and cone input. The rod input into horizontal cell bodies is thus explained on the basis of cone physiology. The half-saturating intensity of 441 nm stimuli for the rod input into cones and horizontal cells was about 400 quanta/mum2/sec and about 160,000 quanta/mum2/sec for the cone input. Little of this difference can be related to the different quantum catching abilities of rods and cones. The spatial properties of horizontal cell bodies and cones have been characterized using stimuli consisting of long slits in conjunction with a continuous cable model. Space constants for horizontal cells ranged from 210 mum to 410 mum, whereas those for cones ranged from 50 mum, or possibly less, to 180 mum. It is argued that horizontal cell bodies of the cat retina form electrical networks, and that the sizes of the receptive fields generated in these networks may be limited by the diameters of the primary and secondary dendrites of horizontal cells. The rod and cone fields of horizontal cell bodies were found to be nearly coextensive in space, arguing against the notion that substantial rod input came from distant, rod-dominated terminal arborizations.

Animals↗
PubMed1977

Clinical applications of echocardiographic studies of the mitral valve. A review.

We have reviewed the clinical usefulness of echocardiographic studies of the mitral valve in mitral stenosis, atrial myxoma, mitral valve prolapse, rupture of chordae tendinae and idiopathic hypertrophic subaortic stenosis. Emphasis has been placed on the recognition of different patterns of mitral valve motion and where necessary, to avoid misinterpretations, appropriates recording techniques.

Aortic Valve Insufficiency↗
PubMed1977

Effects of membrane stabilization on the safety of hypothermic arrest after aortic cross-clamping.

Twenty dogs underwent 1 hour of topical hypothermic arrest; five were untreated, five received methyl prednisolone (30 mg/kg), five received 0.2% procaine, and five received both drugs. Arrest was almost immediate (less than 2 min) with procaine, but was delayed 14 +/- 3 minutes in the other groups. Steroid-treated dogs had the highest post-ischemic left ventricular (LV) blood flows (110 +/- 22 cc/100 g/min) (P less than 0.05). Membrane-stabilizing drugs did not prevent myocardial edema; LV water rose 2% (P less than 0.01) in all groups. Post-ischemic LV compliance was depressed most (55%) in the untreated group, and less after procaine (30%) (P less than 0.05). Postischemic LV performance was depressed 44% (P less than 0.01) in the untreated dogs, and returned to near normal levels with steroid (89% recovery), procaine (97% recovery), and both drugs (95% recovery). We conclude that steroids and/or procaine protect against postischemic myocardial depression but do not prevent myocardial edema. Combining steroids and procaine provide no apparent added benefit, but procaine has the technical advantage of almost immediate cardioplegia.

Animals↗
PubMed1976

Effect of dexamethasone on experimental brain edema in cats.

The authors studied the effects of dexamethasone, 0.3 mg/kg/hr administered intravenously beginning 1 hour before injury, in adult cats with brain edema secondary to cold-induced cortical lesions. Edema was quantitatively measured in cortex, gyral white matter, and central (deep) white matter at 3, 24, 48, and 72 hours, with and without dexamethasone, by determining specific gravity (density) of samples in a continuous gradient column. Cold-induced lesions resulted in edema, which was greatest in the white matter of the injured hemisphere but also present in the contralateral hemisphere. Except for a slight but significant increase in density (decreased edema) of cortex at 24 hours, dexamethasone therapy resulted in no reduction of cold-induced edema, and in some cases increased the edema.

Animals↗
PubMed1976

Bradycardia with mitral valve prolapse: a potential mechanism of sudden death.

Eleven members of a family with a high prevalence of mitral valve prolapse were investigated. Seven had documented sinus bradycardia, and five had mitral valve prolapse. Three patients with both mitral valve prolapse and bradycardia had recurrent syncope reproduced by simple head-up tilting, and in one patient this resulted in asystole. The hemodynamic response to isoproterenol and phenylephrine administration were normal. Supine plasma norepinephrine levels were normal in all three and increased appropriately in two of three patients after tilting. Atrial pacing studies documented marked prolongation of atrial-His intervals and inability to maintain 1:1 atrioventricular conduction when paced at a rate of 120/min. These findings were reversed by atropine. This family shows a close correlation between mitral valve prolapse and potentially lethal bradycardia. Excessive vagal tone is believed to be responsible for both bradycardia and sinus arrest, which in two patients was prevented by permanent demand pacing.

Adolescent↗
PubMed1976

Exercise induced sodium conservation: changes in plasma renin and aldosterone.

Previous studies have demonstrated a renal Na+ conservation during repeated days of exercise in the heat. The present study was intended to describe the role of plasma aldosterone (PAC) in reducing urine Na+ losses during and after 60 min of exercise (60% VO2max) in a warm environment (30 degrees C, 50-53% relative humidity). Additional measurements were made of plasma renin activity (PRA) in an effort to demonstrate the relationship between PRA and PAC. This study shows that a single bout of exercise can significantly reduce urine Na+, Cl-, and H20 excretions for up to 48 hours. Both PRA and PAC were significantly elevated during and immediately after exercise and returned to the pre-exercise level within 6-12 hours of recovery. Subsequently, ingestion of 180 mEq of Na+ each day with ad libitum water intake results in an increased NaCl storage and an expansion of the extracellular volume.

Adult↗
PubMed1975

Horizontal cells in cat retina with independent dendritic systems.

Cat horizontal cells are retinal neurons with two functionally distinct parts: the cell body receives signals predominantly from cones, while the terminal arborization receives predominantly from rods. The long thin process connecting these parts neither generates impulses nor allows significant passive electrotonic conduction between them.

Animals↗
PubMed1975

Bile acid excretion after pull-through operation for Hirschsprung's disease.

Four children with chronic diarrhoea and perianal excoriation after a pull-through operation for Hirschsprung's disease have been shown to have increased but not markedly raised levels of faecal bile acids. Bile acid analysis of the 'bile-rich' duodenal fluid obtained after pancreozymin stimulation in 3 of the patients indicated a marked reduction in the proportion of deoxycholic acid conjugates. These findings are compatible with colonic malabsorption of secondary bile acids in these patients which is related in some way to the pull-through operation, but which is not likely to be the cause of the diarrhoea and the anal excoriation.

Adolescent↗