Biomedical subjects
Publications and source records attributed to S M Specht.
The relationship between admission dates and patients' birthdays was examined for 200 psychiatric and 200 alcoholic patients from a Veterans Affairs Medical Center. Chi-squared analyses indicated that admission dates for subjects of both populations did not occur disproportionately close to their birthdays.
Two experiments were conducted to examine changes in usage of energy and visceral organ mass in Targhee lambs selected on the basis of improved rate and efficiency of growth. In Exp. 1, Targhee ram lambs from a breeding line selected for improved growth rate and feed efficiency and a control line that was maintained without selection for 20 yr were provided with either a high (ad libitum) or low (maintenance) plane of nutrition. Rams were slaughtered and weights of the visceral organs were recorded. Analysis of variance, using a factorial model with BW as a covariant, was used to examine effects of lines of breeding, plane of nutrition, interaction between line of breeding and plane of nutrition, and days on feed. Weights of liver, kidneys, rumen, abomasum, and small and large intestines from lambs receiving a high plane of nutrition were, respectively, 39, 25, 12, 28, 40, and 31% greater than weights of those tissues in lambs receiving a low plane of nutrition. Ruminal weights were 13% greater for rams from the select line of breeding than for those from the control line. In Exp. 2, seven Targhee ewe lambs from the select line and eight from the control line were examined for differences in heat production and energy usage by indirect open circuit respiration calorimetry using a completely randomized design. Fasting heat production of lambs from the select line was 7.8% greater than that of lambs from the control line. Partial efficiencies of ME used for maintenance and tissue accretion were not different between lines of breeding.(ABSTRACT TRUNCATED AT 250 WORDS)
The effects of intrabrainstem injections of the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) into the B3 raphe region (nucleus raphe magnus and nucleus reticularis paragigantocellularis) on early ingestive behavior and nociception were assessed in Sprague-Dawley rat pups during the first postnatal week. Lesions resulted in a marked depletion of serotonin (5HT) in hindbrain without influencing 5HT levels in forebrain. Pretreatment with desipramine (DMI) resulted in a sparing of noradrenergic neurons from neurotoxic effects. The B3 lesion resulted in significant hyperalgesia as reflected by decreased latencies in tail flick testing. Although nipple attachment latencies in suckling tests were slightly increased by the lesion, no notable effects on mouthing or other ingestive-related behaviors were observed in testing conducted in an independent ingestion paradigm. These results suggest that whereas B3 serotonergic neurons may be functioning in an adult-typical manner to regulate analgesia during the early postnatal period, this raphe region may play only a slight role in the modulation of ingestion-related behaviors early in life.
The number of UV-induced mutations to streptomycin resistance in Escherichia coli B/r cells depends on the post-irradiation incubation medium. When cells are incubated on phosphate buffer agar (PBA) as opposed to brain heart infusion agar (BHI), there is an irreversible loss in the number of potential streptomycin resistant mutants which develop. This decrease in mutant numbers is known to occur without a corresponding loss in overall cell viability and cannot be explained in terms of the kinetics of dimer excision. Recent studies have indicated that pyrimidine dimers are the substrate for this repair on PBA. The genetics of PBA repair was investigated by observing the influence of the post-irradiation incubation medium (PBA vs BHI) on the number of streptomycin resistant mutants which develop in E. coli strains deficient in various repair pathways. A recB and recC strain (WP3 recB trp-; WP7 recC trp-) showed repair of potential streptomycin resistant mutants similar to that of B/r when incubated on PBA following irradiation. The medium had no effect on the number of mutants expressed in an excision deficient uvrA- strain (WP2 uvrA trp-) or a polymerase I mutant (P3478 polA thy-). This was interpreted to mean that the loss of streptomycin resistant mutants on PBA involves the excision repair pathway and is dependent on the polA gene product, polymerase I.
Implantation of intraoral cannulas is a procedure that has been typically assumed to be relatively unstressful in neonatal rat pups. To test this assumption, endocrine responses to such implantations were compared with those of other standard procedures. In Experiment 1, corticosterone and growth hormone (GH) levels were assessed in 4-day-old rat pups placed in an incubator for 15 or 60 min following either: no treatment, subcutaneous (sc) injection of 0.9% NaCl, anterior or posterior intraoral cannulation, ice anesthesia or ether anesthesia. Corticosterone levels were elevated relative to nontreated controls 15 min after all treatments except sc injection. These levels remained elevated after 60 min in both cannulation groups and the ice anesthesia group. In Experiment 2, the ability of ether anesthesia to reduce the hormonal response to the cannulation procedures was assessed in addition to examining the hormonal response to intraoral cannulations through the cheek in 4-day-old rat pups. Ether did not attenuate the corticosterone response to either anterior or posterior cannulations. Pups subjected to the cheek cannulation procedure did not exhibit any significant alterations in serum corticosterone levels when compared with nontreated control pups. GH levels were found to differentiate less among the various procedures than corticosterone levels, with GH levels generally being low in all groups, including nontreated control animals. These data suggest that a cheek placement is less stressful than anterior and posterior placements and may provide a viable alternative in studies necessitating the implantation of cannula into the buccal cavity during the early postnatal period.
A total of 260 male and female adult (60-70 days of age) and weanling (22-25 days of age) Sprague-Dawley derived rats were used in these experiments. Subcutaneous administration of histamine (HA) elicited drinking in a dose-dependent manner for both ages tested, although the threshold dose varied with age. A dose of 5.0 mg/kg HA elicited significant increases in water intake for adults, whereas for weanlings a dose of 20 mg/kg HA was necessary. Adult rats exhibited decreased latency to drink after all doses of HA tested, whereas for weanlings, decreased latency was evident only after doses of HA sufficient to elicit increases in water intake. Combined antagonism of H1 and H2 receptors for HA, using dexbrompheniramine and cimetidine, respectively, inhibited HA-elicited drinking in adults and weanlings. Further investigation of the ontogeny of histamine- and food-related drinking may provide a useful approach to examine the physiological mechanisms underlying fluid consumption in adult animals and as they are gradually elaborated during ontogeny.
Eating and drinking in spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats were measured at 5-17 wk of life. The SHR drank significantly more water in 24 h than WKY as early as wk 9, spilled more dry food than did WKY, and exhibited an inverse relation between 24-h water intake and dry food spilled. When eating a meal of dry food after 12 h food deprivation, SHR drank earlier and drank more in a 1-h test than WKY rats. Moreover, SHR exhibited (as early as wk 7) a striking pattern of interrupting eating to drink. This pattern was not present when SHR ate liquid food, and it was attenuated by infusion of water through a cheek fistula. Adult SHR (22 wk) salivated less than WKY in response to intraperitoneal 3.25 mg/kg pilocarpine nitrate. When developing SHR and WKY were maintained on liquid and solid food, SHR gained disproportionately more weight than WKY during development. When young SHR were permitted to drink no more water than WKY rats, the development of hypertension was retarded, and body weight gain was slowed. Because restricted access to food, which produced an equivalent slowing of body weight gain as did restricted access to water, also retarded development of hypertension, it appears that restricted access to water retards development of hypertension due to delayed growth. These results demonstrate that hyperdipsia, apparently caused by deficient salivary function, is not necessary for the development of hypertension in SHR.