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Biomedical subjects

J F Crocker

Publications and source records attributed to J F Crocker.

70 records · Page 4Linked to original sources
PubMed1976

Lethal interaction of ubiquitous insecticide carriers with virus.

Large quantities of presumably nontoxic petroleum oil by-products are introduced into the environment as pesticide dispersal agents and emulsifiers. An increase in viral lethality with a concomitant influence on the liver and central nervous system occurs in young mice previously primed with such chemicals.

Animals↗
PubMed1976

Steroid-induced polycystic kidneys in the newborn rat.

The ability of prednisolone, prednisolone tertiary butyl acetate, and tertiary butyl acetate to induce cysts in the kidneys of 8-day-old rats has been examined following single intramuscular injection of the chemicals into newborn rats. The results indicate that only prednisolone tertiary butyl acetate-treated rats developed cysts to any marked extent. The daily injection of potassium chloride (from Day 2 to Day 7) into the prednisolone tertiary butyl acetate-treated rats prevented the formation of cysts. Similar injection of potassium bicarbonate failed to provide protection. Serum and urine electrolyte (potassium, sodium, and chloride) concentrations were also studied on the day of necropsy. The steroid-treated rats did not develop the hypokalemia observed by previous workers. Changes in electrolyte concentrations were noted in a number of instances, but these could not be causally related to cyst formation.

Animals↗
PubMed1974

Arthritis, deformities, and runting in C5-deficient mice injected with human rheumatoid arthritis synovium.

The pathogenesis of rheumatoid arthritis might be more easily understood and the efficacy of therapeutic measures might be more accurately assessed if a convenient animal replica of this disease were available for laboratory study. Intraperitoneal injection of homogenates of inflamed synovium taken at operation from patients with rheumatoid arthritis produces inflammatory swelling and deformity in the tail and extremities of a proportion of injected mice from a complement (C5)-deficient inbred strain. Swelling of the paws leads to limping of the affected mice. The lesions are transmissible from generation to generation. The results support the theory of a transmissible agent in the inflamed synovium of rheumatoid arthritis patients.

Animals↗
PubMed1973

Human embryonic kidneys in organ culture: abnormalities of development induced by decreased potassium.

Human embryonic kidneys of 5 to 12 weeks of gestation were grown in organ culture. Potassium concentrations of 3 to 6 milliequivalents per liter produced decreased ureteral bud branching, failure of nephron induction, and occasional cystic dilatations of the ureteral bud. Normal development of the kidney occurred at potassium concentrations of 6.5 to 10 milliequivalents per liter. These studies confirm the importance of relative stability of the potassiunm concentration in the development of the embryonic kidney.

Congenital Abnormalities↗
PubMed1972

Renal cystic disease induced in newborn rats by diphenylamine derivatives.

The present study evaluated the effects of diphenylamine (DPA) on the kidneys of rats born of mothers fed the compound and derivatives during the last 6 days of gestation. Cystic lesions were confined to the proximal nephron in newborn rats, in contrast with the localization in the collecting ducts after long-term feeding of DPA to adult rats. Variations observed in the incidence and severity of the cystic changes in several series of animals appeared to depend upon the commercial source of the DPA. Thin-layer chromatography of DPA preparations revealed several components in addition to pure DPA. Lesions were produced in newborn offspring of pregnant rats fed microgram quantities of one of these component, whereas none were seen after feeding of chromatographically pure DPA.

Aniline Compounds↗
PubMed1970

Fetal kidney in organ culture: abnormalities of development induced by decreased amounts of potassium.

Kidneys from fetal mice (10 to 18 days' gestation) were grown in organ culture. Concentrations of potassium less than 9 milliequivalents per liter (10- to 14-day kidneys), and less than 6 milliequivalents per liter (14- to 18-day kidneys), produced abnormal branching, failure of nephron induction, and occasional cystic dilatations of the ureteral bud. These studies emphasize the importance of an environment with a high concentration of potassium for development of the fetal kidney.

Animals↗
PubMedDate not supplied

Central precocious puberty and chronic renal failure: a reversible condition post renal transplantation.

A 3 year-old boy with chronic renal failure associated with prune belly syndrome who developed central precocious puberty is described. He had been maintained on cyclic peritoneal dialysis from age 13 months with creatinine levels of 400-600 mumol/l. Increased linear growth rate probably began at 18 months, and by 38 months of age he had testicular enlargement and pubic hair consistent with Tanner stage 2. Elevated levels of serum testosterone (3.6 nmol/l; normal < 0.7 nmol/l) and luteinizing hormone (LH) (2.8 IU/l; normal < 1.0 IU/l) were demonstrated with a pubertal response to luteinizing hormone-releasing hormone (LHRH) stimulation (peak LH 43.5 IU/l). Other endocrine tests demonstrated hyperprolactinemia (170 micrograms/l; normal 3.4-22 micrograms/l), but normal pituitary-thyroid and pituitary-adrenal functions and normal cranial MR imaging. Despite LHRH-agonist therapy with leuprolide over the next 8 months, he showed an incomplete response with only partial inhibition of basal LH and testosterone levels, and continued significant increments in height standard deviation scores (Ht-SDS) and bone age estimates. However, the sexual precocity appeared fully reversible following a successful living-related renal transplant at age 50 months. Despite discontinuation of leuprolide treatment post-operatively, there was a full reversal of his serum LH and testosterone to a prepubertal profile as well as normalization of the serum prolactin levels. Whereas most boys with chronic renal failure show delayed pubertal development and suppressed linear growth, our patient presents a unique phenomenon of reversible central precocious puberty. The effects of leuprolide therapy in the presence of a uremic milieu and the outcome of successful renal transplantation on sexual precocity are described.

Child, Preschool↗
PubMedDate not supplied

Effects of antipyretics on mortality due to influenza B virus in a mouse model of Reye's syndrome.

OBJECTIVES: To determine the effects of acetylsalicylic acid (ASA) and acetaminophen on mortality due to influenza B infection in neonatal and weanling mice, as well as any synergistic, antagonistic or indifferent effects of the combined antipyretic and virus on mortality in mice pretreated with low doses of an industrial surfactant, Toximul MP8, which has been shown to reproduce many of the features of Reye's syndrome. In vitro studies were done to determine whether ASA or acetaminophen altered the normal, interferon-mediated antiviral responses of mammalian cells. The involvement of ASA or other commonly used xenobiotics in the induction of Reye's syndrome following virus illness has not been resolved; to do so, and to elucidate the underlying metabolic mechanism, requires these studies in an animal model. DESIGN: Prospective animal study. ANIMALS: Newborn (945) and weanling (840) Swiss white mice, divided into 12 subgroups. INTERVENTIONS: Some groups received Toximul MP8 before inoculation with a dose of mouse-adapted human influenza B that produces 30% mortality (LD30); after infection, each subgroup received either placebo, ASA or acetaminophen. Mortality counts were taken daily. The in vitro effects of the antipyretics on interferon response were determined using standard virology techniques. OUTCOME MEASURE: Mortality, analyzed by survival curves (log rank test) or cumulative daily mortality (chi 2 analysis). Plaque-reducing dose (PRD50) was used to determine the outcome of the in vitro analyses. RESULTS: In neonatal mice, only subgroups given combined treatment with acetaminophen and Toximul MP8 had a statistically significant higher mortality rate than with the mice given influenza B alone. In weanling mice, it appeared that ASA shortened the time until death; however, this difference was not statistically significant. In vitro studies demonstrated that both ASA and acetaminophen decreased the interferon-induced antiviral responses of cultured mammalian cells. CONCLUSION: Antipyretics have the potential to exacerbate the consequences of a viral infection, although the specific effects are subtle and appear to be age-related.

Acetaminophen↗