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Biomedical subjects

R C Jones

Publications and source records attributed to R C Jones.

At least 163 records · Page 9Linked to original sources
PubMed1987

Demonstration in live chickens of the carrier state in infectious laryngotracheitis.

Two separate groups of nine-week-old specific pathogen free cockerels maintained in isolation were infected with a field strain of infectious laryngotracheitis (ILT) virus, either by intratracheal or combined intranasal and supraconjunctival inoculation. Birds were monitored for virus shedding from five sites on alternate days during the acute phase and three times weekly until week 17. They were then treated with cyclophosphamide on three consecutive days and thereafter swabbed daily. During the acute phase clinical signs were observed and virus was recovered from ocular and nasal sites for up to six to eight days. Initially after the acute phase no virus could be detected. However, from the seventh week after infection intermittent, apparently spontaneous shedding was detected in four of five birds in each group. There was no clear effect of cyclophosphamide treatment on re-excretion patterns, possibly because of the high levels of virus shedding already occurring. Thus, a carrier state for ILT virus has been demonstrated experimentally in live clinically recovered birds.

Acute Disease↗
PubMed1987

Structural differentiation and fluid reabsorption in the ductuli efferentes testis of the rat.

The ductuli efferentes testis of the rat form a cord which is embedded in adipose tissue. The cord is anatomically differentiated into a proximal cylindrical region, the initial zone, and an ampulla, the coni vasculosi. The initial zone contains six or seven ductuli which leave the rete testis and run in a sinuous path, roughly parallel with one another. However, the ductuli in the coni vasculosi are more sinuous than in the initial zone and they anastomose; pairs join together to form ultimately a single, common ductulus efferens. Stereological studies of paraffin sections and electron micrographs showed that the differentiation of the ductuli into two parts can be recognized at tissue and cellular levels of organization. Stereological and micropuncture studies showed that the ductuli efferentes reabsorb most of the fluid leaving the testis and it was concluded that most reabsorption occurred in the initial zone. It was estimated that the rate of fluid absorption is greater in the ductuli efferentes than in the proximal convoluted tubules of the kidney. The mechanism of fluid transport across the mucosa of the ductuli is considered in the Discussion. It is concluded that transport in vesicles and vacuoles could not account for the rate of fluid reabsorption and that the main mechanism of transport probably involves the coupling of water and active salt transport.

Absorption↗
PubMed1987

Pulmonary artery structural changes in two colonies of rats with different sensitivity to chronic hypoxia.

Chronic hypoxia causes more severe pulmonary hypertension in the Hilltop colony of Sprague-Dawley rats than in the Madison colony and also greater polycythemia and vasoconstriction. This study examines the structural features of the pulmonary artery bed, another contributing factor to hypoxic hypertension. After 14 days of hypobaric hypoxia, in Hilltop rats, more of the intraacinar arteries became muscular, and the medial thickness of intraacinar and preacinar arteries was greater. In Hilltop control rats, muscle was found in more intraacinar arteries, but, paradoxically, acute hypoxic vasoconstriction was less. Thus, while in chronic hypoxia increased muscle correlates with pulmonary hypertension, in control rats the reserve seems to be true. The increased muscle in control Hilltop rats could, however, predispose to the greater muscularization seen after chronic hypoxia.

Animals↗
PubMed1986

Impact of worksite health promotion on health care costs and utilization. Evaluation of Johnson & Johnson's Live for Life program.

This study explores the relationship between exposure to a comprehensive worksite health promotion program and health care costs and utilization. The experience of two groups of Johnson & Johnson employees (N = 5192 and N = 3259) exposed to Live for Life, a comprehensive program of health screens, life-style improvement programs, and worksite changes to support healthier life-styles, was compared with that of a control group (N = 2955) over a five-year period. To account for baseline differences, analyses of covariance produced adjusted means for inpatient hospital costs, admissions, hospital days, outpatient costs, and other health costs. Mean annual inpatient cost increases were $43 and $42 for two Live for Life groups vs $76 for the non-Live for Life group. Live for Life groups also had lower rates of increase in hospital days and admissions. No significant differences were found for outpatient or other health care costs.

Costs and Cost Analysis↗
PubMed1986

Occupational and spatial mobility of temporary Mexican migrants to the U.S.: a comparative analysis.

"U.S. job and spatial mobility are compared here for recent returnee migrants from two Mexican areas--Rio Grande, Zacatecas, in the interior; and Nueva Rosita-Muzquiz, Coahuila, near the U.S. border. Results suggest that the interior migrants fit a hierarchical migrant model: they move up the urban hierarchy from U.S. rural areas to towns and cities, experiencing substantial job mobility at first, but little after reaching the urban sector. Border migrants fit a shuttle migrant model: they return to the same job and place year after year, experiencing little or no spatial and occupational mobility, although they tend to hold somewhat higher status jobs."

Americas↗
PubMed1985

Management of pancreatic trauma.

The majority of patients who sustain penetrating blunt trauma to the pancreas can be managed with sump drainage, including those with gunshot wounds to the head of the pancreas. Pancreatico-duodenectomy may be indicated in 2 to 3 percent of cases of pancreatic injury. Patients who require resection of 80 percent or more of the pancreas and do not have splenic injury should be considered for a Roux-Y anastomosis to the distal pancreas after ductal injury has been proved. Severe injuries to the body of the pancreas are best managed by distal pancreatectomy. The mortality rate due to pancreatic injury has been less than 3 percent and rarely is the cause of death. To support this conclusion, few normotensive patients die, and no patient with an isolated pancreatic injury in our series died. The severity of injury often dictates the appropriate treatment. A conservative approach is indicated for most pancreatic injuries, resulting in shorter operating time and less blood loss in the unstable patient with multiple injuries. Most important is identification of ductal injury at the initial operation and institution of surgical drainage.

Adolescent↗
PubMed1985

Evaluation of antibiotic therapy following penetrating abdominal trauma.

Postoperative infection accounts for significant morbidity and mortality following penetrating abdominal trauma. During a 2 1/2-year period, December 1980 through June 1983, 257 patients sustaining penetrating abdominal injury were initially treated at Parkland Memorial Hospital in Dallas. Following the patient's written consent, they were prospectively randomized to receive, prior to surgery, intravenous clindamycin 600 mg every 6 hours and tobramycin 1.2 mg/kg every 6 hours (CT), or cefamandole 1 gm every 4 hours (M), or cefoxitin 1 gm every 4 hours (C). The antibiotics were continued for 48 hours. Major organ injuries in the three groups were comparable. The overall infection rate was significantly less in the cefoxitin group (13%), compared to cefamandole at 29%, and was comparable to the combination of clindamycin/tobramycin at 20%. The most significant difference followed colon injury. There were 96 patients who sustained colon injuries and the infection rate was CT 33%, M 62%, and C 19% (p = 0.002). If nonoperative wound infections were excluded from the colon group and only severe infections were evaluated, the infection rate was CT 18%, M 38%, and C 13% (p = 0.021). The infection rate was higher in the shock patients and tended to increase as age increased. Enterococcus, Escherichia coli, and Klebsiella pneumoniae were the most frequent aerobes isolated along with anaerobes. Five of six Bacteroides isolates from major infections occurred in the cefamandole group; two of which were in bacteremic patients. The hospital stay corresponded with infection rates, being 11.4 days (CT), 13.1 days (M), and 9.4 days (C). The results of this study indicate that cefoxitin is comparable to the combination of clindamycin/tobramycin and superior to cefamandole when used before surgery in patients sustaining penetrating abdominal trauma. The study suggests that antibiotic coverage should be against aerobes and anaerobes. Routine administration of an aminoglycoside is unnecessary.

Abdominal Injuries↗
PubMed1985

LHRH and analogs: contraceptive and therapeutic considerations.

This paper reviews the developments of the LHRH analogs (agonists and antagonists) in terms of their conceptive, contraceptive and therapeutic utility. It draws upon the mass of data derived from pre-clinical and clinical studies, in both sexes, reinforcing, in particular, the application of the natural LHRH in treating a spectrum of infertile conditions. This profertility approach is contrasted by utilization of the paradoxical antireproductive effect of the agonists as contraceptives, and as a novel therapy for precocious puberty, endometriosis and hormone-dependent tumors, such as prostatic and mammary carcinoma. The LHRH antagonists, by virtue of their singular anti-LHRH properties, are presently being evaluated as antifertility agents, and for the above steroid-dependent pathologies.

Animals↗
PubMed1985

Reovirus-induced tenosynovitis: persistence of homologous challenge virus in broiler chicks after vaccination of parents.

Broiler chicks from a parent flock previously vaccinated with a commercial tenosynovitis (viral arthritis) vaccine were challenged when one day old with a virulent form of the vaccinal reovirus strain. A group from unvaccinated parents was similarly challenged. At three weeks after infection it was found that, while maternal antibody reduced the incidence of lesions of tenosynovitis by about 50 per cent and also the amount of virus in the gut when compared with the group without maternal antibody, the rates of recovery of virus from the hock joints were very similar. The possible epidemiological importance of persistent virus in the joints of clinically protected chicks is discussed.

Animals↗
PubMed1984

Ultrastructure of the epididymis of the tammar, Macropus eugenii, and its relationship to sperm maturation.

The ductus epididymidis of the tammar is lined by an epithelium composed of principal, mitochondria-rich, apical and basal cells, and intraepithelial leucocytes. The epithelium is structurally differentiated into 6 zones referred to as the initial segment, middle segment (3 subdivisions) and terminal segment (2 subdivisions). The occurrence of the initial, middle and terminal segments corresponds quite closely to the anatomical differentiation of the epididymis into a head, body and tail. The initial segment epithelium in the tammar is lower and has shorter and more slender stereocilia than in other mammals which have been described. Otherwise, the structure of the epithelium has similar characteristics in the tammar to that described in other mammals. Spermatozoa begin to develop the capacity for motility within the initial segment, but only show structural signs of maturation in the middle segment. The sperm head rotates through 90 degrees in the proximal subdivision of the middle segment. The cytoplasmic droplet is detached and spermatozoa develop the capacity for motility in the middle subdivision of the middle segment. The cytoplasmic droplets are phagocytosed by the epididymal epithelium of the middle segment. Sperm storage appears to be the main function of the terminal segment.

Animals↗
PubMed1984

Metastatic carcinoid tumor of the appendix. Report of a case and review of the literature.

A case of regional metastatic carcinoid of the appendix is presented and the literature reviewed for indications for right colectomy. Five cases of lymph-node metastasis from primary appendiceal carcinoids less than 2 cm in diameter have been reported. There is no reported case of systemic metastasis occurring after appendectomy for a carcinoid with a diameter of less than 2 cm. Perineural involvement, lymphatic invasion, mesoappendiceal invasion, histologic appearance, and location of the tumor in the appendix seem to be unreliable predictors of clinically significant regional node involvement. It is concluded that a right colectomy is indicated only in patients with carcinoid tumors of the appendix 2 cm or more in diameter, or with residual tumor at the margin of resection.

Adult↗
PubMed1984

The effect of a luteinizing hormone releasing hormone (LRH) agonist (Wy-40,972), levonorgestrel, danazol and ovariectomy on experimental endometriosis in the rat.

The effect of the LRH agonist, Wy-40,972, levonorgestrel or danazol on growth of endometrial explants in the intact female rat was studied. Sc injection of a single compound was begun 3 weeks after transplantation of a section of endometrium to the peritoneal wall. The animals were laparotomized to determine growth of the explant on day 1 of treatment. Injections were continued for 3 weeks at which time the animals were again laparotomized and the condition of the explant examined. Eight weeks after cessation of treatment the animals were sacrificed and the growth of the explant recorded. One or 30 micrograms of the LRH agonist produced a consistent inhibition of explant growth during treatment that was comparable to that obtained by ovariectomy. However, 8 weeks after cessation of injection, the majority of explants exhibited renewed growth while all of the explants in the ovariectomized rats were only visually present. These result suggest that inhibiting or eliminating ovarian steroid production alone will not produce a permanent regression of the endometrial explant. Treatment with 30 micrograms danazol produced no effect and 1, 30 or 100 micrograms levonorgestrel produced none to limited inhibition of explant growth. However, 8 weeks after cessation of treatment explants in animals treated with either levonorgestrel or danazol were smaller in size than recorded prior to treatment. Thus, the inhibiting action of the peptide is rapid, whereas that of the steroids is, apparently, delayed. The observed activity of steroidal and non-steroidal compounds in this study demonstrates the usefulness of a rat model in the study of endometriosis.

Animals↗