The use of pulse oximetry in the immediate recovery phase following dental extractions under general anesthesia in children

Over the past decade, an array of monitoring devices have been developed to continuously assess patient oxygenation. While actual tissue oxygenation is the most desirable measurement, the pulse oximeter offers a non-invasive method of measuring oxygenation of arterial blood. In this study, the arterial oxygen saturation (SaO2) of children presenting for oral surgical procedures under general anesthesia was continuously monitored. We were particularly interested in the saturation during the period from termination of anesthesia until arrival in the recovery room, a potentially critical 2-3 minutes. This study showed that 22.5 per cent of children significantly desaturated (SaO2 less than 90 per cent) during this period - a figure which is in complete agreement with several similar studies done recently. This desaturation preceded not only hemodynamic changes, but frequently changes in tissue and blood colour as well. The authors conclude that children should receive supplemental oxygen in the immediate recovery phase following general anesthesia.

Sensitivity to the anticonvulsant effects of ethanol and pentobarbital in mouse lines genetically selected for ethanol sensitivity

Mouse lines genetically selected for susceptibility [long sleep (LS)] or resistance [short sleep (SS)] to the acute hypnotic effects of ethanol were tested for sensitivity to maximal electroshock seizures. LS mice were slightly more sensitive than SS mice. Ethanol or pentobarbital pretreatment elevated seizure thresholds in both lines. LS and SS mice were approximately equally protected by ethanol, but LS mice were somewhat more protected than SS mice by pentobarbital. These studies do not provide evidence that sensitivity to the anticonvulsant effect of ethanol is mediated by substantially the same genes as those mediating sensitivity to EtOH's hypnotic effects. However, sensitivity to pentobarbital's anticonvulsant effects may be genetically correlated.

The effect of flumazenil on the recovery time of dental patients sedated with diazepam

Flumazenil is an imidazobenzodiazepine that binds specifically to the central benzodiazepine receptor and antagonizes the actions of diazepam and other benzodiazepines. Previous studies in Europe have shown flumazenil at doses of 2 to 30 mg IV to reverse sedation in patients sedated with flunitrazepam, midazolam, and diazepam when evaluated by subjective criteria. The purpose of this study was to determine if flumazenil at 0.015 mg/kg IV was efficacious in shortening the recovery time of young, healthy dental patients sedated with diazepam (0.15 mg/kg IV) and restoring their psychomotor function to presedation levels. A total of 21 patients were randomized to placebo or flumazenil, sedated with diazepam, underwent a restorative dental procedure, and were then administered the test drug. Evaluations of psychomotor function by the Trieger test, Digit-Symbol Substitution test, Romberg test, and nurse questioning were carried out before sedation and at 10-minute intervals after test drug. Observations by the patients and nurses were not significantly different before versus after test drug. The investigator, however, found that flumazenil resulted in more rapid awakening. Patients treated with placebo exhibited significantly greater deficits in the number of dots missed and sum of deviations on the Trieger test than flumazenil-treated patients. Similar time-related deficits were recorded for the Digit-Symbol Substitution test. Flumazenil, at a dose of 0.015 mg/kg, was found to be efficacious in reducing the recovery time after diazepam sedation in dental patients.

Therapeutics and sedation in dentistry

Sedation can help to overcome the fear that prevents many Canadians from accepting dental treatment. This article discusses the indications and contraindications for oral, intramuscular, and inhalation sedation as used by the general dental practitioner for both adult and child patients, with a note on the growing number of specialist dental anesthetists who provide intravenous out-patient sedation. Local anesthesia is discussed with reference to allergic reactions, malignant hyperthermia, and the use of epinephrine as a vasoconstrictor in patients with cardiovascular diseases.

Environmental variables differentially affect ethanol-stimulated activity in selectively bred mouse lines

Low doses of ethanol (EtOH) stimulate activity in an open field in many strains of laboratory mice. We are selectively breeding two lines of mice to exhibit a large (FAST) response on this test, and two other lines to exhibit a small (SLOW) response (Crabbe et al. 1987). The lines initially diverged in response to EtOH, but despite continued selection pressure, the difference between each pair of FAST and SLOW lines has not increased over generations as much as expected. Our practice has been to test animals on the 1st day after saline injection, and repeat the test after EtOH injection 24 h later. Lister (1987) recently demonstrated that the order in which an animal was exposed to EtOH and saline influenced the magnitude of the response to EtOH, with animals tested initially after EtOH having greater stimulation. Middaugh et al. (1987) recently demonstrated that the magnitude of EtOH stimulation was greater under conditions of relatively bright light than under dim light. Using non-selected Swiss mice, the current experiments essentially confirmed Lister's findings. Using FAST and SLOW mice, the predictions of both groups were tested. Both hypotheses were confirmed. Additionally, these experiments demonstrated that the magnitude of the difference between FAST and SLOW mice was greater under bright light than under dim light. The line difference was also greater when tested in the EtOH-Saline order. In experiments with Swiss mice, the possible role of peritoneal irritation in the EtOH effect was eliminated, and the optimal dose and time for demonstrating the effect was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Mice genetically selected for differences in open-field activity after ethanol

Starting from a population of genetically heterogeneous mice, selective breeding is being used to develop lines differing in sensitivity to ethanol-induced open-field activity. Mice are tested twice for 4 min in an open field. The first test is between min 2-6 after injection of saline. Twenty-four hr later, a similar test is performed after injection of ethanol (1.5 g/kg). Two independent FAST lines are being selected for ethanol-induced increases in activity, and two independent SLOW lines are being selected for ethanol-induced decreases. After four generations of selection, the lines have diverged significantly. These lines should be useful for exploring the neuropharmacological basis for the activating and rewarding properties of ethanol.

Genetic differences in anticonvulsant sensitivity in mouse lines selectively bred for ethanol withdrawal severity

WSP (withdrawal seizure-prone) mice exhibit approximately 10-fold more severe withdrawal convulsions than WSR (withdrawal seizure-resistant) mice after identical chronic ethanol exposure. Although WSP and WSR mice do not differ in threshold for seizures elicited by electroconvulsive shock (ECS), WSR mice are more sensitive to ethanol-induced elevation of ECS seizure thresholds. The current experiments demonstrated that WSR mice showed more ECS-induced seizure threshold elevation than WSP mice when tested after the administration of C1-C5 straight-chain alcohols. Whereas the brain concentrations of the C1 and C2 alcohols did not differ between the lines, WSP mice tended to have higher brain concentrations than WSR mice of the C3-C5 alcohols, even though they exhibited the smaller behavioral response in all cases. Thus, the difference between WSP and WSR mice was one of neurosensitivity and could not be attributed to pharmacokinetic differences. The WSR line was also more sensitive to ethchlorvynol, methyprylon, barbital, phenobarbital, pentobarbital, diazepam, valproic acid and phenytoin in this test. Examining loss of righting reflex (RR), we found that WSP and WSR mice did not differ in ED50, latency to lose RR or duration of loss of RR. Thus, the genetic anticonvulsant sensitivity difference is not simply a genetic difference in sensitivity to central nervous system depression between the lines. In summary, WSR mice were more sensitive to the anticonvulsant effects of a variety of compounds than WSP mice, suggesting that some genes influence both ethanol withdrawal seizures and ethanol's anticonvulsant effects.

Specific ethanol withdrawal seizures in genetically selected mice

We are selectively breeding mice prone (WSP) and resistant (WSR) to ethanol withdrawal seizures assessed by handling induced convulsions (HIC). The possibility that differences between the lines in HIC scores are a result of differences in general CNS excitability not specific to ethanol withdrawal was examined. Using treatments which produce generalized seizures (electroconvulsive shock, strychnine, and flurothyl) and gamma amino-butyric acid (GABA) antagonists (picrotoxin, bicuculline, and pentylentetrazol), the ED50 for seizures was determined in the selected lines. In addition, the sensitivity of WSP and WSR mice to the anticonvulsant actions of ethanol against each treatment was determined. Neither the convulsant amperage 50 (CA50) for ECS nor the ED50 for any drug treatment differed for the selected lines. When ethanol (1.5 g/kg) was administered prior to ECS, there was a dramatic differential suppression of ECS in the lines: the CA50 of WSR mice was elevated 5-fold, whereas the CA50 of WSP mice increased only two fold. Ethanol pretreatment also elevated the ED50 for strychnine and flurothyl in WSR mice significantly more than WSP mice, but the line difference was smaller than for the anticonvulsant effect against ECS. The ED50s for the GABA antagonists were not different between the WSR and WSP lines after ethanol pretreatment. We conclude that genetic selection is producing lines of mice that differ specifically in the degree of seizure severity caused by withdrawal from ethanol physical dependence and not in generalized CNS excitability. An increased sensitivity to the anticonvulsant effects of ethanol against some convulsant treatments has appeared as a correlated response to selection in the WSR line.

Ethanol dependence and the pituitary adrenal axis in mice. II. Temporal analysis of dependence and withdrawal

The effects of ethanol dependence and withdrawal on pituitary hormone content and corticosterone release were investigated in AKR/J male mice in a vapor chamber. Both chronic ethanol inhalation and ethanol withdrawal were associated with increased adenohypophyseal-adrenocortical activity. Operationally, ethanol exposure was a stressor. Both physical dependence and withdrawal led to increased secretion/synthesis ratios of peptide hormones. The temporal pattern of pituitary ACTH-IR content changes was different from that of beta-endorphin-IR and alpha-MSH-IR. Differences in the pattern of ACTH-IR and alpha-MSH-IR most probably represent lobe-specific differences in the response to chronic ethanol exposure and withdrawal.

Genetic selection for ethanol withdrawal severity: differences in replicate mouse lines

We report an ongoing within-family selective breeding project for the severity of handling-induced withdrawal seizures in mice made physically dependent on ethanol by inhalation. Two Withdrawal Seizure Prone (WSP) and two Withdrawal Seizure Resistant (WSR) lines have been subjected to five generations of selection, and two control (WSC) lines are maintained. Each WSP line had more severe and each WSR line had less severe withdrawal convulsions than its respective WSC line. Differences relative to control lines were more pronounced in the WSP lines and were not due to differences in effective dose of ethanol. Heritabilities were higher in the WSP lines than in the WSR lines. These lines will be useful for studying physiological determinants of ethanol dependence and withdrawal.

Polygenic and single-gene determination of responses to ethanol in BXD/Ty recombinant inbred mouse strains

Male mice of parent inbred strains C57BL/6J and DBA/2J, and mice from several of the BXD/Ty Recombinant Inbred (RI) strains derived from the cross of the parent inbred strains were tested for responsiveness to ethanol. Separate groups of mice from these strains were characterized for sensitivity to ethanol's effects to increase activity in an open field and to induce ambulatory ataxia in the grid test. The strain distribution pattern of the RI strains indicated polygenic control of both responses to ethanol. Other mice from this battery were tested for acceptance of an ethanol solution, a measure related to preference drinking. This trait may be substantially influenced by a single gene. Mice were then rendered physically dependent on ethanol through inhalation of ethanol vapor for three days. Severity of handling-induced convulsions was used to index the severity of the ethanol withdrawal syndrome. The distribution of the RI strains indicated possible influence of a major gene on ethanol withdrawal severity.

Genetic correlations with ethanol withdrawal severity

A major goal of pharmacogenetic research on alcoholism remains the identification of some "marker" that could predict the liability of a particular individual for a genetic susceptibility to develop alcoholism. The present paper presents evidence that the severity of withdrawal from physical dependence on ethanol varies widely among inbred strains of mice, and that withdrawal severity is negatively genetically correlated with initial sensitivity and magnitude of tolerance to ethanol hypothermia. These correlations are supported by differences in hypothermic response between replicate lines of mice genetically selected for susceptibility and resistance to ethanol withdrawal seizures. The genetic relationships reported suggest that the effects of ethanol on thermoregulation in mice may offer a predictive marker for susceptibility to ethanol physical dependence.

Tolerance to ethanol hypothermia in inbred mice: genotypic correlations with behavioral responses

Hypothermia was studied 5 min before, and 30 and 60 min after intraperitoneal administration of ethanol (3 g/kg) in 20 inbred strains of mice. Ethanol was given daily for 8 days, and temperatures were taken on Days 1, 3, 5, and 8. Tolerance was indexed by the reduction in hypothermia over days. There were large strain differences in baseline temperature, the hypothermic effect of ethanol, and in development of tolerance to hypothermia. Some strains of mice (DBA/1J, DBA/2N, MA/MyJ, and PL/J) did not develop tolerance to the hypothermic effect of ethanol. Initial sensitivity to the hypothermic effect of ethanol was significantly genetically correlated with tolerance development, indicating control of these responses by common genes. Ethanol-induced changes in activity and ataxia, as well as blood ethanol concentrations, were also assessed. Although there were significant strain differences in activity reduction, ataxia, blood-ethanol concentrations, and changes in these parameters during the course of chronic treatment, none of these variables could explain the genetic differences in hypothermic sensitivity and tolerance.

Biphasic effects of ethanol on open-field activity: sensitivity and tolerance in C57BL/6N and DBA/2N mice

Male C57BL/6N (C57) and DBA/2N (DBA) inbred mice were found to differ in open-field behavior after an acute ip injection of ethanol and in the development of tolerance to repeated injections. DBA mice showed only increased activity for 28 min after ethanol doses up to 2.67% g/kg when compared with saline-injected controls. Under the same conditions, C57 mice showed dose-related increases in activity during the first 4 min, followed by dose-related decreases in activity. The effects endured for at least 60 min after injection in both strains. In a third experiment, mice were injected daily with saline or 2.0 g/kg ethanol and tested on Days 1, 5, 9, and 13 for open-field activity. On the 17th day, all mice were tested after an ethanol injection. Neither strain showed tolerance to the activity-stimulating effect of ethanol. Some evidence for tolerance to the effect of ethanol to reduce activity in C57 mice was found. In a fourth experiment, twice-daily injections of ethanol for 10 days produced marked tolerance to the depressant effect of an injection on the 11th day in C57 mice, compared with those in a control group given ethanol for the first time on the 11th day. No tolerance to the stimulant effect of ethanol was seen in C57s. DBA mice were injected twice daily for 19 days but did not display tolerance when tested on Day 10 or on Day 20, Indeed, DBA mice chronically treated with ethanol exhibited more marked stimulation of activity after ethanol than mice treated chronically with saline. Differences in blood ethanol concentrations between the strains could not account for any of the observed differences. Implications for the genetic control of responses to ethanol are discussed.

Investigations on a Babesia isolated from Scottish sheep

The pathognomic, serologic and morphometric identity of a Babesia sp. recently isolated from sheep in Argyllshire was studied. Initially, problems were encountered due to the occurrence of Eperythrozoon ovis as a contaminant of the isolate and treatment with neoarsphenamine failed to remove it. Finally, a combination of oxytetracycline therapy and rapid passage allowed isolation of the Babesia sp. and its preservation in the form of a glycerolized, infected blood stabilate. Inoculation of the stabilate into splenectomized sheep produced a mile non-pyrogenic disease. Serologically the parasite was seen to have no affinity with either of the two Babesia recognized as parasitizing sheep, but some affinity with the cattle parasite B. divergens. Morphometrically it was seen to have affinity with the deer parasite B. capreoli and with the Babesia sp. isolated from red deer in Scotland, and the low number of budding forms of the parasite seen suggested that the parasite might be reproducing slowly in an alien host. It was concluded that the parasite was likely to be B. capreoli derived from red deer via the tick Ixodes ricinus.

Investigations on Babesia motasi isolated from Wales

A number of observations were carried out on the effect of the newly isolated parasite, Babesia motasi (Wales) on intact and splenectomised sheep and on a splenectomised goat. The parasite was not pathogenic for intact animals but caused fever and anaemia in splenectomised ones. B motasi (Wales) was also studied morphologically, morphometrically and serologically. The common form of the parasite was seen to be a double pyriform, the mean length of one side being 2.23 micrometer. It appeared to be morphometrically and serologically close to the other north European B motasi strains but distinct from B motasi (Turkey). In a limited serological survey, experience of infection with B motasi appeared to be common in sheep grazing in coastal areas of North Wales, but rare in a part of South Wales known to harbour the vector tick Haemaphysalis punctata. Transovarial transmission of B motasi by H punctata took place with facility.

Strain differences in pituitary beta-endorphin and ACTH content in inbred mice

The whole pituitary contents of beta-endorphin and ACTH were found to vary widely among 5 inbred strains of mice. beta-endorphin values were 2.5-fold different and ACTH values 1.5-fold. Strains low in beta-endorphin were also low in ACTH. The existence of genetic differences raises the possibility that there exist, or can be developed, strains with extremely low or high levels of these peptides that would aid research directed at elucidating the physiology of opioid peptides.

Quinuronium sulphate for the treatment of Babesia divergens infections of splenectomised calves

Quinuronium sulphate was inoculated into splenectomised calves at various times in relation to artificial infection of the calves with Babesia divergens. When the drug was given one day before the parasites it had no effect on the course of the infection. However, when it was given at the time of onset of fever or haemoglobinuria, development of the infection was arrested. Two weeks after therapy, recrudescences of parasites invariably occurred. In the case of animals treated at onset of fever these recrudescences were accompanied by increasing anaemia. Treated animals resisted subsequent challenge but remained as carriers of the parasite.