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Biomedical subjects

T H Kramer

Publications and source records attributed to T H Kramer.

At least 55 records · Page 3Linked to original sources
PubMed1989

Novel peptidic mu opioid antagonists: pharmacologic characterization in vitro and in vivo.

A series of six synthetic octapeptides, structurally related to somatostatin, demonstrate high affinity and selectivity for mu opioid receptors in radioligand binding assays. The compounds, D-Phe-Cys-Tyr-D-Trp-Lys-Thr-Pen-Thr-NH2 (CTP), D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP), D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP), D-tetrahydroisoquinoline carboxylic acid (D-Tic)-Cys-Tyr-D-Trp-Lys-Thr-Pen-Thr-NH2 (D-Tic-CTP), D-Tic-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (D-Tic-CTOP) and D-Tic-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (D-Tic-CTAP), were tested in vitro and in vivo for agonist and antagonist potency and selectivity. In vitro bioassays included the guinea pig ileum, mouse vas deferens and rabbit vas deferens. In vivo tests included hotplate antinociception and gastrointestinal transit inhibition, performed in mice. In vitro, all six derivatives were competitive, highly selective mu antagonists (pA2 values from 6.4-7.9). The compounds demonstrated varying degrees of intrinsic agonist activity especially in the mouse vas deferens, the least active being CTAP and D-Tic-CTAP, which showed no mu or kappa agonist actions, and delta activity only at very high (greater than 3 microM) concentrations. In vivo, none of these compounds showed antinociceptive actions when administered i.c.v. in mice. All were competitive mu antagonists in the hotplate antinociception test.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Aversive consequences of jejunoileal bypass in the rat: a conditioned taste aversion analysis.

Jejunoileal bypass (JIB) surgery reduces food intake and body weight in obese humans and rats. Human bypass patients report visceral discomfort following surgery, and the present study assessed the aversive consequences of JIB in rats using a conditioned taste aversion paradigm. In Experiment 1 rats given a cherry-flavored solution immediately after JIB surgery subsequently displayed a strong aversion to the cherry flavor compared to Bypass and Sham-Bypass control groups. Rats in Experiment 2 were familiarized with cherry solution prior to surgery and they did not display an aversion to the solution after receiving a JIB. In Experiment 3, Bypass rats who developed a cherry flavor aversion after JIB subsequently lost this aversion following reconnection of their intestinal tract. The rats in Experiment 4 displayed an aversion to a saccharin-flavored chow that was eaten shortly after JIB surgery, although the aversion was not as pronounced as that obtained with the cherry solution. The results suggest that JIB produces a persisting malaise in rats that may contribute to the feeding and weight inhibitory effects of the operation.

Animals↗
PubMed1985

Aversive effects of vagotomy in the rat: a conditioned taste aversion analysis.

Subdiaphragmatic vagotomy suppresses food intake and water intake in normal rats. Since human patients report some nausea and discomfort following vagotomy, the present study assessed the aversive consequences of vagotomy in rats using a conditioned taste aversion paradigm. Rats were given a total subdiaphragmatic vagotomy or sham vagotomy, and were then maintained on either plain water (Vag-Water and Sham-Water groups) or a novel cherry solution (Vag-Cherry and Sham-Cherry groups). When subsequently tested for their water vs. cherry preferences on postoperative days 6, 16, and 26, the Vag-Cherry group displayed a greater aversion to the cherry solution than did the remaining three groups. This result suggests that vagotomy produces visceral malaise in rats which may contribute to the feeding and drinking suppressive effects of the surgery.

Animals↗
PubMed1983

Dietary selection in vagotomized rats.

Adult female vagotomized and control (sham-vagotomized) rats were compared in their consumption of saccharin solutions, intake of solid and liquid sucrose, and selection of purified macronutrient diets. In 30 min/day tests the vagotomized rats drank more saccharin solution (0.05, 0.1, 0.2%) than did control rats, while in a 24 h/day test they drank considerably less saccharin solution (0.2%) than did controls. When offered ad libitum access to granular sucrose and lab chow vagotomized rats did not differ from controls in their sucrose intake, chow intake, or total caloric intake. With a 20% sucrose solution and chow available, however, the vagotomized rats consumed significantly less sucrose and total calories than did the controls. Also, unlike the controls, the vagotomized rats did not consume more of the liquid sucrose than of the granular sucrose, and failed to gain weight on the sucrose diets. When maintained on solid macronutrient diets the vagotomized rats were similar to controls in their selection of the fat, carbohydrate and protein diets. The results demonstrate that vagotomy selectively inhibits the intake of sugar solutions and not high-carbohydrate diets in general. Possible explanations for this effect are discussed.

Animals↗
PubMed1983

Conditioned taste aversion in lean and obese rats with ventromedial hypothalamic knife cuts.

The development of a conditioned taste aversion (CTA) was assessed in rats made hyperphagic with parasagittal knife cuts in the ventromedial hypothalamus (VMH). The animals were water deprived and presented with a .1% saccharin solution paired with injections of either lithium chloride or sodium chloride. In Experiment 1, VMH rats tested at a nonobese weight level did not differ from sham-operated control rats in the acquisition and extinction of the CTA. In Experiment 2, moderately obese VMH rats displayed a stronger CTA than did sham-operated control rats as evidenced by a slower rate of extinction. This effect was not due to the higher absolute dose of LiCl given to the obese VMH rats. A second group of obese VMH rats given an amount of LiCl equivalent to that given to the control rats also displayed retarded extinction of the CTA. The results of these experiments demonstrate that hyperphagia-inducing knife cuts do not alter aversive taste conditioning in rats but that hypothalamic obesity does enhance conditioned taste aversions. This may reflect an obesity-induced suppression in appetitive motivation.

Animals↗
PubMedDate not supplied

High-performance liquid chromatographic analysis of the 2-chloroprocaine metabolite, diethylaminoethanol, in blood and serum.

BACKGROUND AND OBJECTIVES: 2-Chloroprocaine is rapidly metabolized in the blood to yield 2-chloro-para-aminobenzoic acid (an inactive metabolite) and diethylaminoethanol (DEAE). DEAE possesses local anesthetic activity. The only reported assay for DEAE is a colorimetric method. METHODS: Clinical samples of whole blood and serum were obtained from patients receiving stepped intravenous infusions of 3% 2-chloroprocaine. A high pH-dependent liquid-liquid extraction step with diethyl ether was used to eliminate interfering peaks in high-pressure liquid chromatography (HPLC) analysis. Separation and quantitation were performed using HPLC on a polymeric-reversed phase column with a mobile phase consisting of 10% or 20% acetonitrile (for whole blood or serum analysis, respectively) in 50 mm aqueous sodium phosphate buffer, pH = 11.50. The elution order of DEAE and its analogues was tested to interpret the HPLC separation mechanism. RESULTS: Extraction recovery of DEAE from whole blood was 67 +/- 13.5%, from serum, 71 +/- 12.2%, and from water, 75 +/- 2.9%. The high pH value of the mobile phase resulted in sharp, well-resolved peaks with run times of approximately 8 minutes using 20% acetonitrile. The lower limit of detection was 5 ng/mL of DEAE from a 1-mL sample. The elution order of DEAE and its analogues indicated that separation was based on the hydrophobicity of the analytes rather than polar group interactions occurring with silica-based stationary phase. CONCLUSIONS: A new, simple and rapid HPLC method for extraction and measurement of DEAE in whole blood or serum samples is reported here.

Anesthetics, Local↗
PubMedDate not supplied

Use of AA and NA in the treatment of chemical dependencies of traumatic brain injury survivors.

Alcoholics Anonymous and Narcotics Anonymous have been under-utilized in the treatment of chemical dependency in traumatic brain injury survivors. Both offer a social support network and a self-help recovery programme. The fellowships can be viewed as three progressive levels focusing on behavioural, cognitive and gestalt issues. Finally observations and suggestions are offered which may help in incorporating this therapeutic modality which is the most widespread treatment of individuals with chemical dependencies.

Alcoholics Anonymous↗
PubMedDate not supplied

AIDS knowledge and risk behaviours among traumatic brain injury survivors with coexisting substance abuse.

An exploratory needs assessment for AIDS education and prevention was conducted at a traumatic brain injury (TBI) rehabilitation facility among 29 clients that also experience coexisting substance abuse disorders. The results suggest that the surveyed clients possessed a moderate level of information about AIDS. Their knowledge level was variable with a major source of misinformation surrounding the use of condoms. The sample members' knowledge was not related to the type or severity of substance abuse, nor was it associated with safer sexual practices. The present results are compared to earlier findings that used an identical survey with a dual disordered population of psychiatrically impaired substance abusers. The results should help in developing an AIDS education and prevention programme for clients with the dual diagnosis of TBI and substance abuse. Clients need up-to-date information that can be comprehended and used. Education will need to be coupled with approaches that present both behavioural and attitudinal change strategies that are best suited to these clients.

Acquired Immunodeficiency Syndrome↗