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Biomedical subjects

J L Hall

Publications and source records attributed to J L Hall.

At least 19 recordsLinked to original sources
PubMed1992

Plasma glucose levels predict the disrupting effects of adrenoceptor antagonists on enhancement of memory storage.

Adrenoceptor antagonists block the enhancement of memory storage produced by epinephrine injection, but not that produced by glucose injection. The present experiment determined whether adrenoceptor antagonists modify resting blood glucose levels or the magnitude of epinephrine-, glucose-, and footshock-induced increases in circulating glucose levels in a manner related to these previously observed effects on memory. The alpha- and beta-adrenoceptor antagonists, phenoxybenzamine and propranolol, respectively, were injected in rats 30 min prior to administration of epinephrine, glucose, or footshock. Plasma glucose levels were sampled during the next 30 min. Epinephrine-induced increases in plasma glucose levels were potentiated by phenoxybenzamine and were attenuated and delayed by propranolol. The adrenoceptor antagonists did not alter resting plasma glucose levels, or the increases in plasma glucose levels resulting from glucose injection or footshock. These findings suggest that phenoxybenzamine and propranolol alter blood glucose responses to epinephrine injection in a manner which may contribute to attenuation of epinephrine-induced enhancement of memory storage with peripheral injections of adrenoceptor antagonists.

Animals↗
PubMed1992

Effects of fenfluramine and para-chloroamphetamine on sexual behavior of male rats.

The present studies have evaluated the effects of pharmacologically induced release serotonin on sexual responses of male rats during exposure to a sexually receptive female rat. Following acute administration of fenfluramine or para-chloroamphetamine (PCA), significant dose-related decreases in copulatory rate and copulatory efficiency, and increases in ejaculatory latency were observed. These effects were not observed when the animals were pretreated with LY53857, a 5-HT1c/2 antagonist. These studies indicate that acute release of serotonin evoked by these releasing agents has inhibitory effects on sexual sexual drive, capacity to achieve erection and threshold for ejaculation, and these effects are mediated by either the 5-HT1c or 5-HT2 receptor.

Animals↗
PubMed1992

Phlorizin enhancement of memory in rats and mice.

Glucose administration near the time of training or testing elevates blood glucose levels and enhances memory in rodents and humans. The magnitude of increases in circulating glucose levels predicts later retention performance in these and several other situations. Thus, circulating glucose levels appear to contribute to the regulation of memory storage processes. Phlorizin is an inhibitor of glucose transport, which, in view of the effects of glucose on memory, should impair memory. However, rats and mice injected with phlorizin before training in an inhibitory (passive) avoidance task demonstrated significantly enhanced memory performance compared to that of control animals. The effective dose of phlorizin did not significantly change regional brain-relative 3H-2-deoxyglucose uptake or plasma glucose levels. To summarize, phlorizin is a potent memory-enhancing drug. While the mechanism of this enhancement is unknown, it does not appear to include changes in blood glucose levels or brain glucose uptake.

Animals↗
PubMed1992

Acute myocardial ischemia causes a transmural gradient in glucose extraction but not glucose uptake.

We assessed the relationship between myocardial glucose metabolism and blood flow during ischemia in eight open-chest swine. Coronary flow was controlled by an extracorporeal perfusion circuit. Left anterior descending coronary arterial (LAD) flow was reduced by 60%, while left circumflex flow was normally perfused. The rate of glucose uptake (Rg) was measured with a coronary infusion of 2-deoxy-D-[14C]glucose and myocardial blood flow with radiolabeled microspheres. Myocardial biopsies were taken after 50 min of ischemia. Regional arterial-venous glucose difference was calculated as Rg per myocardial blood flow. Subendocardial blood flow decreased from 1.27 +/- 0.19 to 0.25 +/- 0.11 ml.g-1.min-1 (P less than 0.0001). The subendocardial arterial-venous glucose difference was greater in the LAD bed (1.38 +/- 0.35 mumol/ml) than the left circumflex coronary arterial perfusion bed (0.10 +/- 03; P less than 0.01); however, there was no statistically significant difference in the rate of glucose uptake between the two beds. Subendocardial glycogen concentration in the LAD perfusion bed was reduced to 26% of circumflex bed values. In conclusion, acute ischemia stimulated a dramatic increase in glucose extraction; however, this did not compensate for the decrease in blood flow, and thus the rate of glucose uptake did not increase significantly. The high rate of glycolysis is primarily supported by accelerated net glycogen breakdown rather than increased glucose uptake.

Acute Disease↗
PubMed1991

A comparison of the roles of cefamandole and ceftriaxone in abdominal surgery.

In a prospective, randomized study, we compared the ability of ceftriaxone sodium (serum half-life, 8.0 hours) and cefamandole naftate and sodium carbonate (serum half-life, 0.8 hours) to prevent wound infection in 1238 patients undergoing abdominal surgery. Prophylaxis consisted of single-dose therapy at the time of induction of anesthesia, and treatment regimens contained ceftriaxone sodium, 1 g/d intravenously, or cefamandole naftate and sodium carbonate, 1 g intravenously every 6 hours. Except for low-risk biliary procedures, cephalosporin therapy was accompanied by the administration of metronidazole. No significant difference was noted in the incidence of wound infection, ie, 5.6% for the ceftriaxone group (95% confidence interval, 3.8% to 7.4%) and 6.9% for the cefamandole group (95% confidence interval, 4.9% to 8.9%). Single-dose prophylaxis with 1 g of cefamandole naftate and sodium carbonate was relatively inexpensive and provided a cost savings of 64%. When treatment was required, a 23% cost savings was associated with the use of a once-daily dose of 1 g of ceftriaxone sodium.

Abdomen↗
PubMed1991

A multivariate analysis of the risk of pulmonary complications after laparotomy.

We evaluated the relationship between PPC and various putative risk factors in a prospective longitudinal study of 1,000 patients undergoing abdominal surgery. Transient subclinical events were excluded by defining PPC as positive clinical findings in combination with either positive sputum microbiology, unexplained pyrexia, or positive chest roentgenographic findings. The overall incidence of PPC was 23.2 percent (232/1,000). Multivariate analysis identified seven factors which were associated with PPC: ASA classification greater than 2, upper abdominal surgery, residual intraperitoneal sepsis, age greater than 59 years, BMI greater than 25, preoperative hospital stay greater than 4 days, and colorectal or gastroduodenal surgery (overall F score = 33.5, p less than 0.0001). The ASA classification was the most powerful indicator of risk in both the univariate and the multivariate analyses. The combination of ASA classification greater than 1 and age greater than 59 years identified 88 percent (205 of 232) of the patients who developed PPC. These findings provide clinicians and clinical investigators with a simple means of identifying patients who are at high risk of PPC after abdominal surgery.

Age Factors↗
PubMed1990

Ovarian suppression with leuprolide acetate: comparison of luteal, follicular, and flare-up administration in controlled ovarian hyperstimulation for oocyte retrieval.

Adjunct use of leuprolide (LA) in patients undergoing controlled ovarian hyperstimulation with human menopausal gonadotropins (hMG) was evaluated by three protocols: Group F (n = 24) began LA on day 2 of the cycle and Group L (n = 38) began LA on day 23 of the cycle until ovarian suppression, at which time hMG was added. Group FL (n = 17) began LA on day 1 and hMG on day 3. Compared to FL, more ova were collected, more ova fertilized, and more pregnancies resulted per initiated cycle in groups achieving suppression before hMG stimulation. Fewer days were necessary to attain suppression for L vs F. After achieving suppression, patients were maintained on either 0.5 mg LA or 0.25 mg LA daily during hMG coadministration with similar results. Lower maintenance doses of LA during hMG did not decrease the amount of hMG needed but retained the benefits of LA. We recommend luteal initiation of LA to achieve suppression before hMG.

Adult↗
PubMed1990

Studies in fetal wound healing, VII. Fetal wound healing may be modulated by hyaluronic acid stimulating activity in amniotic fluid.

Fetal wound healing occurs rapidly and without inflammation, fibrosis, or scar formation. It is a process fundamentally different from adult wound healing. The mechanisms that underlie such unique healing properties are unknown. However, hyaluronic acid, a glycosaminoglycan component of the extracellular matrix, is prominent throughout the course of fetal wound healing, and is thought to play a major role in the healing process. Amniotic fluid contains high levels of hyaluronic acid. Amniotic fluid also contains a number of potent growth factors that are critical for fetal development. In this report, a new factor in amniotic fluid that stimulates deposition of hyaluronic acid is described. This activity is measured in an in vitro assay system in which cultured fibrosarcoma cells are used as indicator cells. Amniotic fluid thus provides two separate mechanisms for the deposition of hyaluronic acid. One is by exogenous application directly onto fetal skin wounds; the second is by providing a factor to increase the production of hyaluronic acid endogenously, by stimulating cells around the wound site. The resulting hyaluronic acid-rich area may support the ability of the fetal wound to heal with its unique properties.

Amniotic Fluid↗
PubMed1990

Adrenalectomy-induced memory deficits: role of plasma glucose levels.

Circulating glucose levels regulate memory storage under several conditions. This study examined the contribution of blood glucose levels to the transient memory impairment seen in adrenalectomized rats. Inhibitory (passive) avoidance retention performance, blood glucose levels, and glycemic responses to footshock were tested 1, 2, and 8 days after adrenalectomy. Adrenalectomized animals demonstrated a transient inhibitory avoidance deficit 1 and 2 days after surgery which recovered by 8 days. The adrenalectomy-induced memory deficit was accompanied by decreased resting blood glucose levels. In animals tested 2 days after adrenalectomy, this decrease in baseline blood glucose levels was exacerbated by further reductions, rather than the normal increases, in circulating glucose levels after training. The magnitude of blood glucose increases after glucose injection was decreased in adrenalectomized animals tested 2 days after surgery. Posttraining glucose injections restored the retention performance of animals trained 2 days after adrenalectomy to that of sham-operated animals. These findings suggest that abnormalities in blood glucose regulation may contribute, in part, to the transient memory impairment seen after adrenalectomy. Additionally, the results further implicate blood glucose in the regulation of CNS information processing systems.

Adrenalectomy↗
PubMed1990

Loudness growth in 1/2-octave bands (LGOB)--a procedure for the assessment of loudness.

In this paper, a method that has been developed for the assessment and quantification of loudness perception in normal-hearing and hearing-impaired persons is described. The method has been named LGOB, which stands for loudness growth in 1/2-octave bands. The method uses 1/2-octave bands of noise, centered at 0.25, 0.5, 1.0, 2.0, and 4.0 kHz, with subjective levels between a subject's threshold of hearing and the "too loud" level. The noise bands are presented to the subject, randomized over frequency and level, and the subject is asked to respond with a loudness rating (one of: VERY SOFT, SOFT, OK, LOUD, VERY LOUD, TOO LOUD). Subject responses (normal and hearing-impaired) are then compared to the average responses of a group of normal-hearing subjects. This procedure allows one to estimate the subject's loudness growth relative to normals, as a function of frequency and level. The results may be displayed either as isoloudness contours or as recruitment curves. In its present form, the measurements take less than 30 min. The signal presentation and analysis is done using a PC and a PC plug-in board having a digital to analog converter.

Adult↗
PubMed1990

Efficacy of assisted reproductive technology during diagnostic and operative infertility laparoscopy.

Women being evaluated for infertility were offered assisted reproductive technology at the time of diagnostic laparoscopy. Oocyte retrieval was performed after ovulation induction in 33 women, of whom 19 had concurrent operative laparoscopy. Gamete intrafallopian transfer (GIFT) or in vitro fertilization (IVF) and embryo transfer were performed subsequently depending on laparoscopic assessment of pelvic architecture, oocyte maturity, and semen parameters. The clinical pregnancy rate was 24% per cycle and 28% per gamete or embryo transfer (four pregnancies after GIFT and four after IVF/embryo transfer). The clinical pregnancy rate per transfer did not differ significantly between the 19 women who had therapeutic operations in conjunction with laparoscopy (lysis of adhesions and/or fulguration of endometriosis) and the 13 who did not (25 versus 30%; P greater than .05). Assisted reproductive technology can be performed successfully during diagnostic infertility laparoscopy. Operative endoscopic manipulation did not adversely influence pregnancy outcome.

Adult↗
PubMed1990

Clomiphene citrate directly impairs endometrial receptivity in the mouse.

Clomiphene citrate (CC) has known antifecundity effects in animal models. To help define the site of action of this effect, we studied the direct effect of CC on endometrial receptivity by transferring embryos to hormonally prepared prepubertal mice. Prepubertal mice were begun on one of four blinded hormonal preparations consisting of two consecutive 3-day periods of daily injections: oil vehicle, oil-progesterone (P), estradiol (E2)-P, or CC-P. Blastocysts, which had not been exposed to CC, were then surgically transferred to these prepubertal recipients. Fourteen days after embryo transfer, implantations and term pregnancies were counted at necropsy. In this model, CC demonstrated no estrogen agonist effect, and had a significant adverse effect on endometrial receptivity. CC appeared to lower fecundity by a direct endometrial effect.

Animals↗
PubMed1989

Basal body/centriolar DNA: molecular genetic studies in Chlamydomonas.

In Chlamydomonas reinhardtii, mutations on an unusual linkage group, the uni linkage group (ULG), affect structure and function of basal bodies. The ULG shows Mendelian segregation, but its genetic map is circular. Molecular cloning of fragments of the ULG was accomplished by taking advantage of restriction fragment length polymorphisms generated by crosses to Chlamydomonas smithii. These clones were used as probes to determine the size and form of the ULG chromosome; it is a 6-9 megabase linear molecule. Use of the probes for in situ DNA hybridization in cells localized the ULG chromosome to basal bodies.

Centrioles↗
PubMed1989

The role of the 5-HT2 receptor in the regulation of sexual performance of male rats.

The present studies have attempted to evaluate the role of 5-HT2 receptors in the regulation of sexual behavior of male rats by determining the effects of 5-HT2 receptor antagonists, pirenperone, LY53857 and LY281067, and a 5-HT2 receptor agonist, DOI. The administration of 1 mg/kg s.c. pirenperone produced a total suppression of ejaculatory response and lower doses had no effect. However, the administration 0.1 mg/kg s.c. of either LY53857 or LY281067 restored ejaculatory capacity to rats that were unable to ejaculate and produced significant decreases in ejaculatory latency in rats with full sexual capacity. Although all of these agents are 5-HT2 antagonists, LY53857 and LY281067 lack the additional monoaminergic activity of pirenperone. Since the effects of pirenperone were opposite from the effects of the selective 5-HT2 antagonists, the suppressive effects of this agent were probably related to its other monoaminergic activity e.g. alpha 1 antagonist activity. This proposal was supported by the observation that the administration of prazosin, an alpha 1 antagonist, significantly increased ejaculatory latency and suppressed the stimulatory effects of LY53857. In contrast to the stimulatory effects of the selective 5-HT2 antagonists, the administration of DOI, resulted in a suppression of sexual performance, which was blocked by pretreatment with LY53857.

Amphetamines↗
PubMed1989

Glucose enhancement of performance on memory tests in young and aged humans.

Recent findings indicate that glucose administration enhances memory processes in rodents. This study examined the effects of glucose on memory in humans. After drinking glucose- or saccharin-flavored beverages, college-aged and elderly humans were tested with modified versions of the Wechsler Memory Scale. Beverages and tests were administered in a counter-balanced, crossover design, enabling within subject comparisons. The major findings were: (1) glucose enhanced memory in elderly and, to a lesser extent, in young subjects; and (2) glucose tolerance in individual subjects predicted memory in elderly, but not in young subjects on both glucose and saccharin test days.

Adolescent↗
PubMed1989

Use of peri-operative antibiotics in abdominal surgery: a criterion audit.

OBJECTIVE: To evaluate the peri-operative use of parenteral antibiotics in 100 patients undergoing abdominal surgery. METHOD: Prospective criterion audit. RESULTS: There is a need for the close monitoring of antibiotic usage within hospitals, because 39% of the patients received inappropriate antibiotic therapy.

Abdomen↗
PubMed1988

Food-associated intoxicants.

The association of toxic substances with human foods has long been recognized. While intrinsic compounds appear during storage as a result of spoilage by chemical processes or by contamination with micro-organisms. In the numerous stages of food production from source to table there are many opportunities for contamination. This article reviews the wide spectrum of food-associated toxicants, outlining the mechanisms by which these substances reach the food products. To illustrate the diversity of these mechanisms, some notable examples of mass contamination of food are quoted. The presence of toxic substances in human food is, and will continue to be, a challenge for toxicologists, and a source of concern for the public, for industry, and for the scientific community.

Animals↗