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Biomedical subjects

E A Stone

Publications and source records attributed to E A Stone.

108 records · Page 6Linked to original sources
PubMedDate not supplied

Acute stress disrupts risk assessment behavior in mice.

The effects of stress on risk assessment behavior in mice were studied by examining latency to emerge from a safe compartment into a large, well-lit open field. In the first experiment different groups of mice were exposed for 1 h to tube restraint, fixed interval 2-min foot shock, or attack by an aggressive conspecific. Nonstressed controls were left undisturbed in the home cage. Thirty minutes following stress animals were placed in the safe compartment and latency to emerge was recorded. Results showed all of the stressed groups exhibited significantly faster emergence latencies than nonstressed controls. In the second experiment the duration of this effect was examined by testing different groups at varying intervals following tube restraint stress. Results showed that mice tested 0.5 and 1 h following stress exhibited short entry latencies and reduced head poke responses. Performance had returned to nonstress levels 3 h after stress. These data suggest that stress reduces caution by disrupting risk assessment behaviors.

Aggression↗
PubMedDate not supplied

Potentiation by propranolol of stress-induced changes in passive avoidance and open-field emergence tests in mice.

Noradrenergic and serotonergic systems are known to be stimulated during various forms of stress. The present study examined the effect of the beta-adrenergic serotonin1A receptor blocker propranolol on the ability of stress to elicit behavioral inhibition in mice. Mice were given the drug before immobilization or tube-restraint stress, and then were tested for either passive avoidance performance or time to emerge into an open field. Propranolol markedly potentiated stress-induced increases in latency in both of these tests, suggesting that it exacerbated reactions to stress. These results agree with previous data indicating that under certain conditions, propranolol can potentiate the effects of stress in rodents. The results support the hypothesis that the response of the noradrenergic and/or serotonergic systems to stress may have anxiolytic or antistress effects.

Animals↗
PubMedDate not supplied

Are glial cells targets of the central noradrenergic system? A review of the evidence.

It has been suggested by a number of investigators that glial cells as well as neurons are targets of the central noradrenergic system. This important hypothesis, however, has not been presented previously in a systematic and unified manner. The present review was therefore undertaken to accomplish this. The evidence supporting noradrenergic action on glia consists primarily of findings that beta-adrenoceptors, norepinephrine (NE)-stimulated cyclic AMP (cAMP) responses and glycogen are localized preferentially in glial cells and that beta-receptor density and glycogen hydrolysis are under the control of neuronally released NE. While there is some disagreement as to the extent to which beta-receptors are preferentially localized in glia, there is a consensus that most glycogen in the forebrain is localized in this cellular compartment. The presumed function of the noradrenergic action on glia appears to be the release of glucose for production of energy, the synthesis of neurotrophic factors such as nerve growth factor, and the release of substances which may affect local neurotransmission including taurine, cAMP and its metabolites. These glial responses may be intimately related to the electrophysiological actions of NE on neurons.

Animals↗
PubMedDate not supplied

Studies on the cellular localization of biochemical responses to catecholamines in the brain.

Studies were undertaken to determine the cellular localization of the cyclic adenosine monophosphate (cAMP) response of various forebrain regions to beta-adrenoceptor stimulation. Using brain slices, it was found that the gliotoxin, fluorocitrate (FC), which blocks metabolism selectively in glial cells, virtually abolished the cAMP response to beta-receptor stimulation whereas the neurotoxin, kainic acid (KA), was without effect. FC was confirmed by electrophysiological recording to be selective for glial cells in the brain slices. Similar results were found for these agents on in vivo brain cAMP responses to beta-receptor stimulation using a new microdialysis technique to measure in vivo responses. It is concluded that the cAMP response to beta-adrenoceptor stimulation in various regions of the forebrain occurs predominantly in glia. To determine if this could be correlated with a second biochemical response to beta-receptor stimulation, preliminary studies were undertaken on the localization of the immediate early gene, c-fos, produced in the brain after in vivo stimulation of beta-receptors. It was found that unlike the cAMP responses the c-fos response to beta-receptor stimulation occurs predominantly in neurons. The possible relationship of these two responses is discussed.

Animals↗
PubMedDate not supplied

Survival and development of maternally deprived rats: role of body temperature.

Rat pups, 10-12 days old, survived maternal deprivation if kept warm at 35 degrees, but died within 6 days if allowed to become hypothermic at a room temperature of 23 degrees. Normal body temperatures facilitated feeding, but even without food, warm pups survived starvation longer than cool ones. Increased survival could not be attributed to decreased oxygen consumption, and warm pups lost more body water and solids than cool pups. Striking differences in development that may have affected survival were observed over 72 hr of separation without food. Cool pups showed a virtual arrest of the growth of the tail, fur, tibia, and femur, and failed to increase brain weight, protein, DNA, RNA, and catecholamine contents. Warm pups showed developmental growth more comparable to that of normally mothered pups and significantly exceeded controls in the rate of accumulation of brain norepinephrine and dopamine.

Animals↗
PubMedDate not supplied

A retrospective evaluation of the rectal pull-through technique. Procedure and postoperative complications.

Ten animals (8 dogs and 2 cats) with distal rectal lesions were treated by surgically resecting the affected segment of the rectum by the rectal pull-through technique. There were four malignant tumors, three benign tumors, two inflammatory lesions, and one malignant tumor that extended histologically to the margins of a previous surgical excision. Postoperative complications were tenesmus (7 animals), fecal incontinence (4 animals), rectal bleeding (4 animals), and abscess formation (1 animal). Dehiscence and stricture were not observed. The four animals with malignant tumors survived less than 12 months after surgery. One of the four animals still living has persistent fecal incontinence. The rectal pull-through technique is described and illustrated.

Animals↗
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Ureterocolonic anastomosis in ten dogs with transitional cell carcinoma.

Ureterocolonic anastomosis (UCA) was performed in 10 dogs with transitional cell carcinoma of the urinary bladder trigone or the urethra, or both. All grossly visible tumor was excised. All of the dogs recovered from anesthesia and surgery and had anal continence with no urine leakage. One dog died of undetermined causes 7 days after surgery. Nine dogs survived 1 to 5 months. The owners of eight of the dogs considered their dog's quality of life to be acceptable. Four dogs were euthanatized because of neurologic disease, three of which also had nausea and vomiting. The neurologic and gastrointestinal signs may have been caused by hyperammonemia, metabolic acidosis, and uremia. Blood ammonia levels were elevated in two dogs with neurologic signs. Hyperchloremic metabolic acidosis that was reversible with bicarbonate therapy was diagnosed in five dogs. All of the dogs were azotemic because of intestinal recycling of urea. Serum creatinine concentrations increased in four dogs after surgery. Drug-induced renal disease may have developed in two dogs. Pyelonephritis developed in five kidneys, two of which had outflow obstruction and two had bilateral hydroureteronephrosis before the UCA. In this small number of dogs, surgical excision of transitional cell carcinoma was not curative with six dogs having confirmed metastatic lesions at the time of death.

Anastomosis, Surgical↗
PubMedDate not supplied

Subtotal canine prostatectomy with the neodymium: yttrium-aluminum-garnet laser.

A technique was developed for subtotal prostatectomy in dogs with the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. In six normal dogs, full-thickness necrosis of the prostate occurred if the central-lateral region within 5 mm of the urethra was photoablated at 60 watts for 1 second. Moderate to superficial necrosis occurred when the prostate within 5 mm of the urethra was photoablated at 35 watts for 2 seconds or 60 watts for 0.5 second. At necropsy, leakage of the urethra occurred in two dogs at sites treated at 60 watts for 1 second. In a clinical study, complications associated with subtotal prostatectomy with the Nd:YAG laser (n = 6) were compared with complications associated with prostatic drainage (n = 6) in dogs with prostatic disease. Intraoperative death (2/6 dogs) and nocturnal incontinence (4/4 surviving dogs) occurred with subtotal prostatectomy. Uncontrolled prostatic infection (2/6 dogs) occurred with prostatic drainage and resulted in the death of one dog on day 11. Four of five dogs surviving prostatic drainage developed recurrent urinary tract infection.

Abscess↗
PubMedDate not supplied

A retrospective study of inguinal hernia in 35 dogs.

Inguinal hernia was associated with trauma in five dogs and was considered nontraumatic in 30 dogs. There were 11 males, 13 intact females, and six spayed females with nontraumatic inguinal hernia. Six dogs had bilateral hernias. Five dogs were younger than 4 months at the time of diagnosis. In 11 older dogs with nontraumatic inguinal hernia, the hernias were identified less than 7 days before surgical repair; in 14 older dogs, the hernias had been recognized for 1 to 60 months. Clinical signs in dogs without small intestinal incarceration were usually limited to a visible or palpable mass without pain or systemic illness. Herniorrhaphy approaches included inguinal, midline with contralateral ring evaluation, and celiotomy with or without inguinal exposure. Fat and omentum were the most common hernial contents. Small intestine was within the hernias of 12 dogs. Six dogs had nonviable small intestine. Postoperative complications included two incisional infections, one incisional dehiscence, two cases of peritonitis and sepsis associated with bowel leakage after intestinal resection and anastomosis, and one hernia recurrence. The overall prevalence of postoperative complications was 17%, and the mortality rate was 3%. Vomiting for 2 to 6 days was predictive of nonviable small intestine. Dogs younger than 2 years were at 11 times greater risk for nonviable small intestine than dogs older than 2 years. Four of five dogs with nontraumatic inguinal hernia and nonviable small intestine were intact males, whereas none of 13 intact females were affected. Only one of 14 dogs with longstanding hernias had nonviable small intestine.

Animals↗
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In vitro loss of tensile strength and elasticity of five absorbable suture materials in sterile and infected canine urine.

The loss of breaking strength and elasticity of five absorbable suture materials (polydioxanone [PDS-II], polyglycolic acid [PGA], polyglactin 910 [PG-910], polyglyconate [GTMC], and chromic gut) after in vitro incubation in sterile, Escherichia coli- and Proteus mirabilis-inoculated canine urine was studied. Biomechanical testing, in a controlled environment, was performed during the 28-day study period. Polydioxanone and chromic gut retained greater than 90% of their original strengths after 28 days of incubation in sterile urine and 87% of original strengths in E. coli-inoculated urine. Polyglyconate retained 24% and 18% of original strength, respectively, after incubation in sterile and E. coli-inoculated urine for 28 days. Polyglycolic acid and PG-910 retained less than 30% of original strength in sterile urine and only 7% in E. coli-inoculated urine after 21 days of incubation. In P. mirabilis-inoculated urine, loss of tensile strength and elongation was significant for all suture materials. Polyglycolic acid and PG-910 lost all strength after 24 hours of incubation. Polydioxanone lost all strength after 7 days of incubation, whereas GTMC retained 19% at day 7. Chromic gut retained 78% at day 7 and 16% after 21 days of incubation, however, the absence of normal phagocytic destruction of chromic gut in this in vitro study may have artificially elevated these values. In sterile urine with chemically modified pH, loss of strength and elongation was greater in alkaline urine than in neutral or acidic urine for all types of suture materials.

Animals↗
PubMedDate not supplied

Management and complications following trigonal-colonic anastomosis in a dog: five-year evaluation.

Urinary diversion procedures in the dog have been described for both benign and malignant processes involving the bladder, urethra, or both. These procedures are performed rather infrequently, primarily because of the potential complications associated with urinary diversion into an intact gastrointestinal system. A case managed for five years following trigonal-colonic anastomosis for lymphocytic-plasmacytic urethritis is presented, along with a review of urinary diversion techniques. Postoperative management recommendations following urinary diversion are discussed.

Anastomosis, Surgical↗