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Biomedical subjects

J Chase

Publications and source records attributed to J Chase.

16 recordsLinked to original sources
PubMed1992

Biosynthesis and endocrine control of the production of the German cockroach sex pheromone 3,11-dimethylnonacosan-2-one.

The biosynthesis and endocrine regulation of sex pheromone production in the female German cockroach (Blattella germanica) were determined. Radio-TLC and radio-GLC were used to demonstrate the metabolism of 3,11-dimethylnonacosane, a major cuticular lipid component, to the corresponding alkan-2-ol and methyl ketone. [11,12-3H2]-3,11-Dimethylnonacosan-2-ol was efficiently metabolized to the methyl ketone, and radio-GLC showed that the methyl ketone product from both experiments was coeluted with a methyl ketone standard. A comparison of the metabolism of the labeled dimethylalkane and dimethylalkan-2-ol by age and sex showed that both males and females from day 1 through day 9 after adult emergence readily metabolized the alcohol to the corresponding methyl ketone, whereas only females of 5-9 days postemergence efficiently converted the labeled dimethylalkane to the corresponding methyl ketone. Application of the juvenile hormone analog hydroprene induced significant increases in the conversion of the labeled hydrocarbon to the methyl ketone in starved adult females as well as in females fed a protein-free diet, conditions under which endogenous juvenile hormone biosynthesis is nearly undetectable. These data show that the methyl ketone sex pheromone is formed by the hydroxylation and oxidation of the 3,11-dimethylalkane at the 2 position, show that the age- and sex-specific step in this process is the conversion of 3,11-dimethylnonacosane to 3,11-dimethylnonacosan-2-ol, and provide evidence that juvenile hormone regulates sex pheromone production in the German cockroach.

Animals↗
PubMed1992

Comparison of pregnancy rates following in vitro fertilization-embryo transfer between the donors and the recipients in a donor oocyte program.

Our in vitro fertilization (IVF) program provides a unique opportunity to evaluate influences of hormonal milieu on pregnancy outcome, by using a shared pool of oocytes obtained by donors (in exchange for financial assistance). The study presented herein evaluated 38 retrieval cycles (28 oocyte donors/22 recipients). No difference in mean number of embryos transferred was seen (2.7 in the donors vs 2.8 in the recipients). However, a statistically significant difference was seen in the pregnancy rates per retrieval (10.5% donors vs 29% recipients) and per transfer (4/35, 11.1%, vs 11/34, 32.3%). Abortion rates were similar (25% donor, 27.2% recipients). These data suggest that other reports of higher pregnancy rates from donor oocyte programs may not be due exclusively to better-quality oocytes. Possibly a negative effect of hyperstimulation or adverse endometrial environment of the donor (possible chronic endometritis) may explain these data.

Abortion, Spontaneous↗
PubMed1992

A microsomal fatty acid synthetase from the integument of Blattella germanica synthesizes methyl-branched fatty acids, precursors to hydrocarbon and contact sex pheromone.

Methyl-branched fatty acids present in the integument of the German cockroach, Blattella germanica, were identified by gas chromatography-mass spectrometry of their methyl esters and reduction products (alkanes) as n-3-, n-4-, n-5-, n-7-, n-8-, and n-9-monomethyl fatty acids and as n-5,9-, n-3,9-, and n-3,11-dimethyl fatty acids with 16 to 20 total carbons. These fatty acids have the same branching patterns as do the major hydrocarbons of this insect, including 3,11-dimethylnonacosane, the precursor to the major contact sex pheromone, and are presumed to be intermediates in hydrocarbon formation. A novel microsomal fatty acid synthetase (FAS) located in the integument of this insect incorporated [methyl-14C]methylmalonyl-CoA into methyl-branched fatty acids as demonstrated by radio-high-performance liquid chromatography. A cytosolic FAS is also present in the integument. Both the microsomal and the soluble FAS incorporated [methyl-14C]methylmalonyl-CoA into fatty acids, but only the microsomal FAS was able to efficiently use methylmalonyl-CoA as the sole elongating agent. This is the first report of the characterization of methyl-branched fatty acids from the integument of an insect and of an integumental microsomal FAS that incorporates methylmalonyl-CoA into branched fatty acids.

Acyl Coenzyme A↗
PubMed1991

Hepatic arterial infusion chemotherapy with complete hepatic venous isolation and extracorporeal chemofiltration: a feasibility study of a novel system.

When chemotherapeutic drugs with low liver extraction are used for hepatic arterial infusion (HAI), dosage limits are usually determined by systemic rather than hepatic toxicity. If such agents could be administered by HAI at dosages limited by hepatic toxicity, regional drug exposure and therapeutic efficacy might be significantly enhanced. We report herein a novel system that achieves complete hepatic venous isolation using a dual-balloon vena cava catheter that can be inserted percutaneously. This catheter is connected to a carbon filter in an extracorporeal venous bypass circuit to recover drug that is not absorbed by the liver after HAI. The hemodynamic response to this system was evaluated in six pigs. When the animals were placed on the extracorporeal circuit, we observed a 22% decrease in cardiac output that was well tolerated without significant change in blood pressure. When the filter was incorporated into the circuit, cardiac output was significantly reduced (50%); however, continuous infusion of phenylephrine rapidly normalized blood pressure, heart rate, cardiac output, and left ventricular filling pressures. Initial testing of chemofiltration efficacy was performed in four of the six animals, the remaining two animals being used only to assess hemodynamic response. One each of the four tested animals received either doxorubicin (3 or 9 mg/kg), mitomycin C (1 mg/kg), or cisplatin (1 mg/kg) by HAI. The filter removed over 90% of hepatic venous doxorubicin and mitomycin C and 65% of hepatic venous cisplatin. This feasibility study confirms that hepatic venous isolation with chemofiltration can significantly reduce systemic exposure to high-dose chemotherapeutic agents given by HAI.

Animals↗
PubMed1990

Evaluating the potential for powered mobility.

It has been 5 years since Chris was evaluated for a powered wheelchair, and she has had two occupational therapists and three physical therapists since the evaluation and training process began. It has been a long and arduous process, full of triumphs and setbacks. Chris's level of functional mobility, self-confidence, and ability to socialize, however, have increased dramatically as a result of her perseverance. The powered wheelchair, which she can control herself, has increased her ability to explore her environment and to master the increased activities made available through an expanded environment.

Adult↗
PubMed1986

An effective five-drug antiemetic combination for prevention of chemotherapy-related nausea and vomiting. Experience in eighty-four patients.

Antiemetics of known efficacy have been shown to block mainly one of three neurotransmitter receptors in the brain. A combination of antiemetics, designed specifically for outpatient use and consisting of metoclopramide, thiethylperazine, diphenhydramine, dexamethasone, and diazepam, is capable of blocking multiple sites in the emesis pathway. Eighty-four patients receiving highly emetic chemotherapy (85% received cisplatin) completed 200 trials of this five-drug combination using two similar regimens. Complete control (i.e., no nausea or vomiting) was achieved in 45% and two or fewer episodes of vomiting was experienced in 72% of these 200 trials. The mean number of vomiting episodes was 1.65, the median 1.0, and the range 0-15. Sedation was nearly universal, although no serious toxicity was encountered. Thus, this antiemetic combination designed for outpatient use proved highly effective in controlling nausea and vomiting associated with highly emetic anticancer treatment.

Adolescent↗
PubMed1977

Antigenic shift of visna virus in persistently infected sheep.

Visna viruses isolated from persistently infected sheep were antigenically distinct from the plaque-purified virus used for inoculation. The selection of antigenic variants under antibody pressure, thought to occur in vivo, was reproduced in sheep cell cultures inoculated with plaque-purified visna virus and maintained in antibody. Antigenic shift may be a mechanism for persistence of virus in slow or recurrent viral infections.

Animals↗
PubMed1976

Experimental arthrogryposis caused by viral myopathy.

Immobilization of the embryo has been postulated to cause the joint deformities in arthrogryposis multiplex congenita (AMC). Experimental damage to the motor neurons or pharmacologic blockade of neuromuscular transmission has previously resulted in typical joint changes of AMC. In the present investigation, we have studied the effects of paralysis produced by a viral myopathy on joint development. Coxsackievirus A2 was injected intravenously into chick embryos on the seventh day of incubation. Within 48 hours, severe myositis and paralysis resulted. Electron microscopical and immunofluorescence techniques demonstrated virus in muscle cells. Within three to four days after infection, the muscle had virtually disappeared. Ankylosis of joints, corresponding to that seen in human AMC, occurred. This study shows that primary myopathy with paralysis can produce arthrogrypotic joint deformities. The possibility of a viral etiologic factor in some human cases of AMC should be considered.

Animals↗