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Biomedical subjects

D F Smith

Publications and source records attributed to D F Smith.

At least 307 records · Page 17Linked to original sources
PubMed1982

Dopaminergic effects on tail-flick response in spinal rats.

R-Apomorphine (0.02-1.75 mumol/kg), administered by intrathecal infusion to spinalized rats, caused a dose-dependent increase in tail-flick latency. The effect of R-apomorphine was counteracted significantly by the dopaminergic receptors antagonists cis-flupenthixol (0.20-3.94 mumol/kg) and (+)-butaclamol (0.78 mumol/kg), but not by their enantiomers nor by phenoxybenzamine (29.40 mumol/kg) or methysergide (29.40 mumol/kg). The findings suggest that dopaminergic mechanisms play a role in the modulation of nociception in the spinal cord.

Animals↗
PubMed1982

Monoaminergic mechanisms in stress-induced analgesia.

Male albino rats given brief transcutaneous electric footshock showed an elevation in tail-flick response latency--an effect called stress-induced analgesia (SIA). The influence of pretreatments altering monoaminergic neurotransmission on SIA were studied. Inhibition of monoamine storage in presynaptic vesicles reduced SIA, while additional inhibition of serotonin synthesis abolished the SIA response. In contrast, inhibition of serotonin synthesis alone failed to influence SIA. Blockade of dopaminergic receptors reduced SIA, while induction of dopaminergic receptor supersensitivity failed to affect footshock-induced analgesia. Neither inhibition of monoamine oxidase nor blockade of noradrenergic neurotransmission affected SIA significantly. The results suggest that serotonergic and dopaminergic rather than noradrenergic mechanisms contribute to SIA.

Animals↗
PubMed1982

Effect of emotions on nociceptive threshold in rats.

Tail-flick latency was measured in male rats exposed to inescapable footshock for 2 min (0.8 mA, 1 sec every 5 sec) in rats that witnessed effects of footshock on other rats and in rats exposed to a strong auditory stimulus (8 kHz, 96 db SPL) either intermittently (1 sec every 5 sec) or continuously for 2 min. A significant increase in tail-flick latency occurred in rats exposed to footshock as well as in rats that only witnessed footshock. Continuous auditory stimulation also had an analgesic effect, while intermittent stimulation similar to the sound produced by rats given footshock failed to affect tail-flick latency significantly. The analgesic effect of witnessing footshock habituated rapidly and was counteracted by naloxone (10 mg/kg IP), while naloxone failed to affect audiogenic analgesia. Analgesia produced by witnessing a noxious treatment is probably mediated by an emotional reaction. It is suggested that the phenomenon be termed "emotiogenic analgesia"

Animals↗
PubMed1982

The identification of structures and conditions responsible for right side tympanitic resonance (ping) in adult cattle.

In review of the case records of all cattle greater than or equal to 2 years of age admitted to the Large Animal Hospital of the New York State College of Veterinary Medicine in a 3-year-period, 366 were identified as having areas of right side tympanitic resonance (ping) due to gas distention of intra-abdominal structures. The source of the ping was identified as abomasum in 137 cattle, various segments of the intestinal tract in 157 cattle, and peritoneal gas in 2 cattle. In 70 cattle, no identification was made as to the source of the ping. In 151 (41%) of the cattle with areas of ping, both the clinical and definitive (surgical or necropsy) identification of the source of the ping was recorded. In these cattle, the sensitivity and predictive value of the clinical identification were determined for each structure. The sensitivity and predictively; for cecum and/or ascending colon, the sensitivity and predictive value were both 87%. Of all cattle in which a right side ping was recorded, the principal final diagnoses were: left displacement of the abomasum (116), right displacement of the abomasum (77), abomasal (and omasal) and volvulus (60), other gastrointestinal conditions (73), nongastrointestinal conditions(40).

Abomasum↗
PubMed1981

Volvulus of the bovine abomasum and omasum.

Two cows with right-side volvulus (torsion) of the abomasum and omasum were embalmed, and the viscera were dissected to study the topography and mechanisms of the condition. In both cases, the abomasum and omasum were greatly distended and formed a loop with the cranial part of the duodenum. The loop was twisted 360 degrees counter-clockwise, as viewed from the rear or from the right, around an axis through the lesser omentum. The reticulum was drawn caudally on the right side of the rumen by its attachment to the fundus of the abomasum. Study of a model of the stomach and omenta indicated that the more probable mode of rotation was in a sagittal plane. The mode of rotation made no difference in the result or in the method of reduction, which was deflation and rotation in the opposite direction. pressure and tension damage to the ventral vagal trunk and to the blood vessels would indicate a guarded prognosis.

Abomasum↗
PubMed1981

A monosialoganglioside is a monoclonal antibody-defined antigen of colon carcinoma.

The antigen of a monoclonal antibody that is specific for cells of human carcinoma of the colon is a monosialoganglioside as determined by the direct binding of antibody to thin-layer chromatograms of total lipid extracts of tissues. Binding of antibody to chromatograms is detected by autoradiography after the application of iodine-125-labeled F(ab')2 of rabbit immunoglobulin G antibodies to mouse immunoglobulins.

Adenocarcinoma↗
PubMed1981

Optimal perfusion rate determined for in situ intestinal absorption studies in rats.

Iopanoic acid was used as a model compound to study the effect of the intestinal perfusion rate on the mean absorption clearance. Absorption of iopanoic acid followed first-order kinetics, with a first-order absorption rate constant (ka) linearly dependent on the dry intestinal weight. An absorption clearance--time plot revealed three phases. Phase I represented an equilibration phase, Phase II was a uniform phase, and Phase III was a physiological deterioration of the animal under prolonged anesthesia. The variability in the observations during Phase II of the absorptive clearance--time profiles was assessed statistically, and the minimum occurred at 9.9 microliters/sec (0.594 ml/min). The relation between the coefficient of variance (CV) and the perfusion rate is given by CV = (-5.52 X 10(-5)Q3 + (2.78 X 10(-3)Q2 - (3.87 X 10(-2)Q + 0.243, where Q is the perfusion rate through the intestinal lumen. These studies demonstrate that an optimal flow rate exists for minimizing the variability in in situ absorption studies. The dependency of the absorption clearance on the intestinal perfusion rate appears to conform to the convective diffusion model.

Animals↗
PubMed1981

Role of monoamines in behavior of reserpinized rats given tranylcypromine stereoisomers.

The effects of tranylcypromine stereoisomers [(+)-TCP and (-)-TCP] on behavior were studied in reserpinized rats. Rats given reserpine showed a behavioral syndrome characterized by hypoactivity. Administration of (+)-TCP to reserpinized rats led to a dose-dependent increase in their locomotor activity. At a dose of 15 mg/kg, (+)-TCP produced activation, stereotypy and hyperstimulation in reserpinized rats. In contrast, (-)-TCP failed to influenced the behavior of reserpinized rats reliably. Pharmacological studies using agonists and antagonists of monoaminergic functions showed the actions of (+)-TCP to depend on presynaptic serotonergic and catecholaminergic functions. The results provide another example of stereoselective effects of tranylcypromine stereoisomers on behavior mediated mainly by monoaminergic neurotransmission.

Animals↗
PubMed1981

The role of consciousness in stress-induced analgesia.

Male rats received unavoidable footshock administered while either awake or under Halothane anaesthesia. Tail-flick threshold was measured subsequently in awake rats. An elevation in pain threshold indicative of stress-induced analgesia (SIA) appeared in rats shocked while awake, but not in those shocked while anaesthetized. The findings suggest that conscious processes are necessary for the occurrence of SIA.

Analgesia↗
PubMed1981

Central and peripheral effects of lithium on amphetamine-induced hyperactivity in rats.

Rats received 0.15 M LiCl either as a central treatment in the lateral cerebroventricles (2x20 microliter/rat) or as a peripheral treatment in the peritoneal cavity 15 ml/kg). The central treatment produced high lithium concentrations (1-1.2 mmol/kg) in the brain while peripheral treatment produced high lithium levels (1-2 mmol/1) in the blood at convenient times for behavioral tests. The central treatment antagonized amphetamine-induced hyperactivity but failed to affect open field behavior in otherwise untreated rats. In contrast, the peripheral treatment suppressed open field activity in otherwise untreated rats but failed to influence behavioral effects of amphetamine. The findings demonstrate differences between central and peripheral actions of LiCl on behavior in rats and show lithium to have central actions on hyperactivity induced by amphetamine.

Animals↗
PubMed1981

The molecular cloning of a dispersed set of developmentally regulated genes which encode the major larval serum protein of D. melanogaster.

We have isolated chromosomal segments of D. melanogaster DNA that encode the alpha, beta and gamma polypeptides of the major larval serum protein (LSP1) from libraries of recombinant phage. The recombinant DNAs hybridize in situ to polytene chromosome regions 11A, 21D of 61A, consistent with the known cytogenetic positions of the alpha, beta and gamma genes, respectively. The three genes each encode a 2.85 kb polyadenylated RNA molecule. We have positioned these coding sequences, by both Southern hybridization analysis and R loop mapping. Heteroduplex analysis reveals comparatively close homology between the alpha and beta genes, less homology between the beta and gamma genes and least homology between the alpha and gamma genes.

Animals↗