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Biomedical subjects

S F Lowry

Publications and source records attributed to S F Lowry.

At least 181 records · Page 10Linked to original sources
PubMed1979

Nutritional manipulations and tumor growth. I. The effects of starvation.

The effects of starvation on tumor and host growth were studied in growing male Fischer rats bearing methylcholanthrene-induced sarcomas. Tumor growth was evaluated by changes in weight, volume, and incorporation of tritiated methyl thymidine into tumor DNA, (dpm/microgram DNA). Host growth was followed by changes in total body weight, carcass weight, and dpm/microgram liver DNA. All periods of starvation (24 to 96 hr) caused significant decreases in host body and carcass weight and dpm/microgram liver DNA. Changes in tumor weight and tumor volume in fed and starved animals were equal. Tumor dpm/microgram DNA in starved animals increased (P less than 0.005) relative to fed controls at 48, 72, and 96 hr starvation intervals. Starvation allows continued tumor growth while host wasting occurs, and is accompanied by increased tumor dpm/microgram DNA in this system.

Animals↗
PubMed1979

Nutritional manipulations and tumor growth. II. The effects of intravenous feeding.

The effects of acute parenteral nutritional manipulations on tumor and carcass growth were examined in the rat. Carcass mass was maintained in animals fed diets either orally or intravenously. Reduction in liver incorporation of tritiated methyl thymidine and increases in liver fat content in the total parenteral nutrition groups indicated that the high carbohydrate, high nitrogen, intravenous diet was less than optimal. Tumor growth as measured by changes in volume, weight, DNA content, or nitrogen content was unaffected by the various nutritional regimens. Tumor dpm/microgram DNA was reduced by those intravenous regimens that were associated with hyperglycemia. Host carcass weight, can be maintained with intravenous nutrition, but normal growth is not restored by the current intravenous regimens.

Animals↗
PubMed1979

Abnormalities of zinc and copper during total parenteral nutrition.

Changes in serum zinc and copper levels were studied in 19 tumor bearing patients undergoing parenteral nutrition (TPN) for five to 42 days. Before initiation of intravenous feeding mean serum zinc and copper concentrations were within normal limits but during TPN levels decreased significantly below those measured prior to parenteral nutrition. During TPN nitrogen, zinc, and copper intake, urinary output and serum levels were studied prospectively in nine of these patients. These nine patients exhibited positive nitrogen retention based upon urinary nitrogen excretion, but elevated urinary zinc and copper excretion and lowered serum zinc and copper concentrations. Neither blood administration nor limited oral intake was consistently able to maintain normal serum levels of zinc or copper. Zinc and copper supplementation of hyperalimentation fluids in four patients studied for five to 16 days was successful in increasing serum zinc and copper levels in only two. The data obtained suggest that patients undergoing parenteral nutrition may require supplementation of zinc and copper to prevent deficiencies of these elements.

Adolescent↗
PubMed1979

Effect of work-induced hypertrophy on skeletal muscle of tumor- and nontumor-bearing rats.

Synergistic muscles (soleus and plantaris) from a gastrocnemius-tenotomized hindlimb were compared to the same muscles in a sham-operated hindlimb in both tumor-bearing and non tumor-bearing rats. In nontumor-bearing animals muscle from the tenotomized hindlimb had a significant increase in wet weight (26%), percent-water (5%), and total nitrogen/muscle (10%) consistent with muscular hypertrophy. In tumor-bearing animals, muscle from the tenotomized hindlimb had a significant increase in wet weight and percent water, but there was no significant difference in total nitrogen/muscle. As the tumor burden increased, the final muscle weight, in both the tenotomized and sham-operated hindlimb, was found to decrease proportionately. Only in animals with large (23% body wt) tumor burdens did hypertrophied muscle weigh significantly less than sham-operated muscle from nontumor-bearing animals. This indicated that, in rats with large tumor burdens, work-induced hypertrophy was unable to preserve muscle mass despite the fact that hypertrophied muscle was 24% heavier than contralateral sham-operated muscle.

Animals↗
PubMed1978

Isolated aneurysms of the iliac artery.

Clinical and diagnostic material were gathered from eight cases of iliac aneurysms encountered over a ten-year period. From the literature, descriptions of 36 lesions were also reviewed to identify their outcome when treated conservatively. Six of the eight aneurysms treated as expected resulted in eventual rupture. Although 48% of all patients (those in the present series and those reported in the literature) had symptoms before rupture, the symptoms of intact iliac aneurysms often mimicked urological or neurological diseases. In contrast to persons with abdominal aortic aneurysms, only 36% of all patients had a palpable abdominal or rectal mass before rupture. In 65% of all cases, noninvasive roentgenography failed to show the lesions. An aneurysmal lesion was often (23%) present in the opposite iliac system as well. Ninety-three percent of all patients survived after an elective operation, but only 48% survived after an emergency iliac aneurysmectomy after rupture occurred.

Aged↗
PubMed1978

Parenteral vitamin requirements during intravenous feeding.

Serum vitamin levels of 40 patients undergoing parenteral nutrition over a 5-to 42-day period were studied while the subjects received daily water-soluble and once weekly fat soluble vitamin formulations intravenously. Initial serum deficiencies of vitamins A, C, and folate were noted in a large portion of the severely malnourished population. At the replacement levels used in this study a small number of patients developed subnormal levels of vitamins A and D. Improvement in levels for vitamin C and folate were noted for most patients. Vitamin B12 deficiencies were not noted in any patient. Currently available commercial vitamin preparations can be used with safety in the parenterally nourished population and recommended guidelines for weekly infusion of both water and fat soluble vitamins are presented.

Adolescent↗
PubMed1978

Topical effects of 16,16 dimethyl prostaglandin E2 on gastric acid secretion and mucosal permeability to hydrogen ions in dogs.

The effects of luminal instillation of 16,16 dimethyl PGE2 (dmPGE2) on gastric acid secretion and back diffusion of H+ were studied in anaesthetised dogs which were prepared with a segment of the greater curvature of the stomach mounted in a double lumen chamber. This model permitted simultaneous evaluation of two segments of mucosa, one control and the other test, supplied by the same vascular pedicle. Imfusion of histamine (1.0 microgram/kg/min, intravenously) stimulated brisk acid secretion in both chambers. Topical application of 25 microgram dmPGE2 in 20 ml 0.3 M HC1 to the test chamber for 30 minutes prevented acid secretion from the test mucosa during a second histamine infusion. Since the control chamber showed no evidence of inhibition this indicates that dmPGE2 acted directly on the secretory cells, rather than after absorption from the bloodstream. This observation, however, does not exclude a possible local effect on mucosal blood flow. Direct exposure of the gastric mucosa to dmPGE2 increased the rate of back diffusion of H+ because of disruption of the permeability barrier, indicated by increased H+ back diffusion, Na+ efflux, and a reduction in potential difference. However, H+ loss was small compared to the reduction in acid output.

Animals↗
PubMed1978

Oxygen consumption during cimetidine and prostaglandin E2 inhibition of acid secretion.

Oxygen consumption was determined during cimetidine and 16,16-dimethyl prostaglandin E2 inhibition of acid secretion in exteriorized segments of the greater curvature of dog stomach. Steady-state acid secretion during histamine infusion correlated well with O2 consumption (r = 0.85, P less than 0.01). Cimetidine and 16,16-dimethyl prostaglandin E2 inhibition of acid secretion produced a reduction of oxygen consumption to resting levels. In contrast, oxygen consumption did not decrease appreciably during thiocyanate inhibition of acid secretion. These observations suggest that the inhibitory action of cimetidine and 16,16-dimethyl prostaglandin E2 precedes, whereas that of thiocyanate is at a point beyond the transfer of energy to the process of acid production.

Animals↗
PubMed1978

Effects of intra-arterial infusion of prostaglandin E1 on gastric secretion and blood flow.

The effect of intra-arterial infusion of Prostaglandin E1 (PGE1) on gastrict total and mucosal blood flow and acid secretion was studied in an exteriorized, chambered preparation of canine fundic stomach. Total gastric blood flow was measured simultaneously by venous outflow and by gamma-labeled microspheres. Mucosal blood flow also was measured by microspheres. Intra-arterial infusion of PGE1 at 1.0 microgram/min completely inhibited histamine-stimulated acid secretion. This inhibition was accompanied by a significant increase in both total (p less than 0.01) and mucosal blood flow (p less than 0.01). The ratio of mucosal to total blood flow remained unchanged during histamine stimulation (78 +/- 4%) and PGE1 inhibition (79 +/- 4%). The results suggest that inhibition of acid secretion can occur in the face of increased blood flow. This observation is contrary to the generally accepted concept that inhibition of acid secretion always is associated with a decrease is mucosal blood flow.

Animals↗
PubMed1978

Essential fatty acid deficiency in total parenteral nutrition: time course of development and suggestions for therapy.

Thirty-two patients receiving total intravenous nutrition were studied prospectively for biochemical and clinical signs of essential fatty acid deficiency. Individual constituents of the phospholipid fraction were examined consecutively and the triene:tetraene ratio was determined. All patients nourished parenterally for 4 weeks had triene:tetraene ratios of greater than 0.4. Levels of eicosatrienoic and linoleic acid were abnormal after 1 week, and arachidonic acid levels became abnormal after 2 weeks of fat-free parenteral nutrition. Skin lesions suggestive of essential fatty acid deficiency developed in two patients studied. Biochemical abnormalities responded rapidly to the intravenous administration of Intralipid.

8,11,14-Eicosatrienoic Acid↗
PubMed1976

The role of house staff in undergraduate surgical education.

An analysis of the contribution made by house officers in fulfilling the objectives for a comprehensive clerkship experience was undertaken by questioning members of the 1975 medical class. The objectives examined over a broad spectrum of surgical disease and are applicable to any general surgical clerkship. In addition, the instruction received in technical skills was analyzed and deficiencies were noted. Major subject areas related to surgical disease were examined for adequacy of house staff instruction, and an estimation of hours per week devoted to the clerkship experience by house and staff was derived. The university-private hospital training program at this institution permitted a comparison of instruction between these clerkship settings. Some deficiencies did appear in intellectual and technical instruction in both clerkship environments. These deficiencies, however, usually were related to a paucity of patient material and to the lack of opportunity for clinical instruction which ensues from these cases. With few exceptions, the house staff provided nearly one third of the knowledge base acquired during the junior medical student experience. The results indicate that very little difference exists between the didactic role of the house officer in either the university or community hospital environment.

Education, Medical, Undergraduate↗
PubMedDate not supplied

Anti-cachectin/TNF monoclonal antibodies prevent septic shock during lethal bacteraemia.

Bacterial infection of the mammalian bloodstream can lead to overwhelming sepsis, a potentially fatal syndrome of irreversible cardiovascular collapse (shock) and critical organ failure. Cachectin, also known as tumour necrosis factor, is a macrophage-derived peptide hormone released in response to bacterial lipopolysaccharide, and it has been implicated as a principal mediator of endotoxic shock, although its function in bacterial sepsis is not known. Anaesthetized baboons were passively immunized against endogenous cachectin and subsequently infused with an LD100 dose of live Escherichia coli. Control animals (not immunized against cachectin) developed hypotension followed by lethal renal and pulmonary failure. Neutralizing monoclonal anti-cachectin antibody fragments (F(ab')2) administered to baboons only one hour before bacterial challenge protected against shock, but did not prevent critical organ failure. Complete protection against shock, vital organ dysfunction, persistent stress hormone release and death was conferred by administration of antibodies 2 h before bacterial infusion. These results indicate that cachectin is a mediator of fatal bacteraemic shock, and suggest that antibodies against cachectin offer a potential therapy of life-threatening infection.

Animals↗