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Biomedical subjects

D C Jones

Publications and source records attributed to D C Jones.

At least 109 records · Page 6Linked to original sources
PubMed1982

Dose-response study of chloroform carcinogenesis in the mouse and rat: status report.

Chloroform is being administered to male Osborne-Mendel rats and to female B6C3F1 mice at concentrations of 0 (negative control), 200, 400, 900 or 1800 ppm in the drinking water. Matched control groups of both species receive a volume of water identical to that consumed by the corresponding 1800 ppm groups. At this writing, the animals have completed 23 months on test. Negative control and CHCl3-treated rat groups have shown typical growth curves, with dose-related relative decrements in body weight evident throughout the study. Following decreases in CHCl3 groups during the first 8 weeks, rat water consumption values have continued to increase slowly, but persistent relative dose-related decrements are evident. No initial treatment-related decrements are evident. No initial treatment-related mortality was seen in the rats. Survival is 21, 41, 45, 76, 70 and 64% for the negative control, 200, 400, 900, 1800 ppm and matched control groups, respectively. Survival values for mice at three weeks were 99, 94, 74 and 76% for the 200, 400, 900 and 1800 ppm groups, respectively. Mortality was apparently related to markedly decreased fluid consumption among some of the treated mice. Subsequent mortality has been less than 15% for all mouse groups. Except for acclimation effects during the first 2-3 weeks, body weights for the treated mouse groups have been generally within 10% of negative control values. Tissue changes in decedents have been similar in treated and control groups, both in rats and mice. Terminal sacrifice and histologic evaluations will be initiated after completion of 24 months on test.

Animals↗
PubMed1981

Rapid hepatoma induction in rats by dipentylnitrosamine and its modification by other carcinogens.

Dipentylnitrosamine (DPN), administered in the diet at a concentration of 2,000 ppm to Fischer-344 rats, produced hepatomas in 27% of both males and females within 8 weeks. Bile-duct carcinomas were also produced. All animals also showed liver nodular hyperplasia and bile-duct cell proliferation. Feeding DPN at 1,500 ppm produced hepatomas or bile-duct carcinomas in 7% of the males and varying degrees of nodular hyperplasia and duct cell proliferation after 8 weeks of feeding. The total cumulative dose after feeding 2,000 ppm DPN was of the order of 7,700 mg/kg body weight in males and 8,200 mg/kg in females. There was a 28% weight decrement in animals feed 2,000 ppm DPN when compared to controls but no mortality. DPN carcinogenicity was enhanced when DPN was combined with a liver carcinogen, cycasin (fed as cycad not flour, equivalent to 160 ppm cycasin). No effect on DPN carcinogenicity was found in rats fed DPN and lasiocarpine, another known liver carcinogen with antimitotic activity. Neither was there any effect of DPN carcinogenicity in rats fed DPN and N-butyl-N-(4-hydroxybutyl) nitrosamine or N-methyl-N'-nitro-N-nitrosoguanidine. In contrast, the trisodium salt of nitrilotriacetic acid reduced the hepatocarcinogenic action of DPN. The enhancement of DPN carcinogenicity with cycasin is compatible with the hypothesis that DPN-induced liver cell populations (hyperplastic nodules) can resist the cytotoxic effect of cycasin and differentiate rapidly towards hepatomas, while other areas of the liver are suppressed.

Animals↗
PubMed1981

Deep venous thromboembolism in patients undergoing inguinal lymph node dissection for melanoma.

Deep venous thromboembolism (DVT) was studied in 44 patients with clinical Stage I, II, and III melanoma undergoing staging and therapeutic inguinal lymph node dissection. The ability of two noninvasive methods of surveillance, the phleborheograph (PRG) and the 125I fibrinogen scan to detect deep venous thrombosis was determined by comparison with prospective bilateral lower extremity venograms. In addition, the therapeutic impact, both beneficial and detrimental, of low dose heparin, 5000 units administered subcutaneously two hours prior to and every eight hours after operation was determined in a double blind study. The sensitivity of the PRG and 125I fibrinogen scan were both 20%. There were five deep venous thrombi, and two pulmonary emboli for a combined incidence of DVT of 13.6% for the entire patient population. However, there was no significant difference in the incidence of DVT between the two groups. The heparin-treated patients had an increased total volume (796 +/- 516 versus 388 +/- 208 ml; p less than 0.05), and duration of wound drainage (9 +/- 4 versus 13 +/- 6 days; p less than 0.05).

Bed Rest↗
PubMed1981

"Cold" bone scans in acute osteomyelitis.

The diagnosis of acute osteomyelitis is often very difficult during the first 24 to 48 hours. Bone scanning has been a useful adjunct in this diagnosis by demonstrating increased uptake in the area or areas of involvement. Occasionally the pathological area is "cold" on scanning, which may lead to a misdiagnosis. This paper presents three cases demonstrating this unusual finding.

Acute Disease↗
PubMed1980

Comparison of proprietary elemental and whole-protein diets in unconscious patients with head injury.

Forty men who had sustained head injury were randomly assigned to one of five groups to receive 0.2 g nitrogen/kg body weight/day as either an elemental or a whole-protein diet. Three proprietary elemental and two whole-protein diets were compared. The mean daily nitrogen intake was below 0.2 g/kg in all groups, and was significantly lower in the groups receiving elemental compared with whole-protein diets. Energy intake was significantly different only between one group receiving an elemental and one receiving a whole-protein diet. Mean daily urinary nitrogen excretion was significantly lower in the groups receiving elemental diets, and mean daily nitrogen balance was negative in all groups except one receiving a whole-protein diet. Reduced nitrogen intakes occurred particularly with the elemental diets, which often provoked reflex vomiting or gastric stasis. The need to introduce diets at reduced strength made a negative balance almost inevitable, but nutritional balance seemed to be more readily achieved with the whole-protein diets. More work is needed to assess the relative merits of these proprietary diets compared with tube feeds prepared in hospitals.

Craniocerebral Trauma↗
PubMed1979

A comparison of mathematical models for estimating right ventricular volumes in animals and man.

Volume of 19 right ventricular canine casts and 11 right ventricular human casts were obtained by water displacement and compared to three different mathematical models for estimating right ventricular volumes by biplane cineangiography. In the canine studies, significant linear correlation coefficients were obtained using the longest measured length method (r = 0.92), the triangular modification of Simpson's rule (r = 0.93), and the elliptical modification of Simpson's rule (r = 0.93). The human studies resulted in similar significant correlation coefficients of 0.96, 0.97, and 0.97, respectively. Although the highest correlation with the lowest standard error of estimate was obtained using the triangular model, all three mathematical models produced volume estimations that feel within acceptabe biological limits of accuracy.

Animals↗
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

Autotransplantation of cryopreserved parathyroid tissue in man.

Human cryopreserved parathyroid autografts have been performed in six patients following reoperative parathyroid surgery. All patients were rendered hypoparathyroid by their most recent reoperation. Parathyroid tissue was successfully autotransplanted after as long as eighteen months of cryopreservation. Viability and expected in vivo function of cryopreserved parathyroid tissue may be predicted by in vitro testing of parathyroid hormone secretion in response to varying ambient calcium concentration. Parathyroid cryopreservation with subsequent autotransplantation is a practical solution to the problem of permanent hypoparathyroidism that may follow multiple surgical procedures for persistent hyperparathyroidism.

Calcium↗
PubMed1979

Applications to undergraduate nursing courses.

Education of nurses has in recent years developed in centres of higher education, but with a rapid rise in courses offered concern has been expressed that too few suitable applicants may be available. This study has attempted to ascertain actual demand for the courses available by cross-referencing applications to a sample of courses, and has demonstrated a downward trend of suitable applications over the two years 1975 and 1976. A cautionary approach to establishing new courses or increasing numbers on existing courses may be advisable and further comparable work will be carried out to assess the validity of the trends already found.

Curriculum↗