Genetic differences in the ethanol sensitivity of GABAA receptors expressed in Xenopus oocytes.

Animal lines selected for differences in drug sensitivity can be used to help determine the molecular basis of drug action. Long-sleep (LS) and short-sleep (SS) mice differ markedly in their genetic sensitivity to ethanol. To investigate the molecular basis for this difference, mRNA from brains of LS and SS mice was expressed in Xenopus oocytes and the ethanol sensitivity of gamma-aminobutyric acid A (GABAA)- and N-methyl D-aspartate (NMDA)-activated ion channels was tested. Ethanol facilitated GABA responses in oocytes injected with mRNA from LS mice but antagonized responses in oocytes injected with mRNA from SS animals. Ethanol inhibited NMDA responses equally in the two lines. Thus, genes coding for the GABAA receptor or associated proteins may be critical determinants of individual differences in ethanol sensitivity.

Ethanol sensitivity of the GABAA receptor expressed in Xenopus oocytes requires 8 amino acids contained in the gamma 2L subunit.

Expression of brain mRNA or cRNAs in Xenopus oocytes was used to determine what subunits of the GABAA receptor are required for modulation by barbiturates, benzodiazepines, and ethanol. Mouse brain mRNA was hybridized with antisense oligonucleotides complementary to sequences unique to specific subunits and injected into oocytes. Antisense oligonucleotides to the alpha 1, beta 1, gamma 1, gamma 2S + 2L, gamma 2L, or gamma 3 subunits did not alter GABA action or enhancement by pentobarbital. Action of diazepam was prevented by antisense oligonucleotides to gamma 2S + 2L and reduced by antisense sequences to gamma 2L, but was not affected by the other oligonucleotides. Ethanol enhancement of GABA action was prevented only by antisense oligonucleotides to gamma 2L (which differs from gamma 2S by the addition of 8 amino acids). Expression of either the alpha 1 beta 1 gamma 2S or the alpha 1 beta 1 gamma 2L subunit cRNA combination in oocytes resulted in GABA responses that were enhanced by diazepam or pentobarbital, but only the combination containing the gamma 2L subunit was affected by ethanol.

Spinal cord injury "outliers": an analysis of etiology, outcomes, and length of stay.

Spinal cord injury (SCI) requires significant and expensive medical intervention, including prolonged hospitalization and intense in-patient treatment and rehabilitation. Development of predictive models for lengths of stay in spinal cord injury patients provides a method for early prediction of patients that will require greater care, incur greater costs, and need more intensive medical and rehabilitative services. Early identification of SCI patients at high risk of extended lengths of stay will also allow physicians to treat those patients more aggressively, and permit families, as well as sponsors, to estimate the costs of long-term care. Results of a forward-conditional stepwise multiple logistic regression indicate that the model including age at injury, number of days to rehabilitation admission, number of pressure ulcers, number of medical complications, level of injury, and sponsor of initial hospitalization significantly (chi2 = 220.063, p < 0.001) predicts outliers in terms of rehabilitation length of stay. Overall, the percentage of persons who were correctly classified by the multivariate model was 96.92% (chi2 = 66.85, p < 0.001). The correct prediction rate for outliers was 46% and nonoutliers 97%. This model provides a tool that can be used by health providers, sponsors and patients to aid in the identification of individuals with SCI that may require extended lengths of stay. Today, unfortunately, our health care system is burdened by the heavy influence of economics rather than functional outcome. We maintain that implementation of this model will help to improve care of the SCI patient by early identification of those in need of more extensive resources and improve the economic efficiency needed to provide maximal functional outcome.

Toxicity evaluation of petroleum blending streams: reproductive and developmental effects of a distillate from light alkylate naphtha.

A distillate of light alkylate naphtha (CAS number 64741-66-8; LAN distillate) was administered via inhalation, 6 h/d, 7 d/wk to 4 groups of Sprague-Dawley rats (10/sex/dose) at target concentrations of 0 (filtered air control), 5, 12.5, or 25 g/m3 with the highest dose exceeding 60% of the lower explosive limit of LAND. Exposure began 2 wk prior to mating and continued throughout gestation until postnatal d 4 for females or for 8 consecutive weeks for males. No apparent clinical signs indicative of systemic toxicity were observed in the F0 and F1 animals of either sex. Inhalation exposure to LAND up to and including the 25 g/m3 dose level had no effect on parental food consumption, body weights, absolute and relative organ weights, and reproductive indices. All groups had comparable delivery data and a fertility index > or 80%. Pups in all groups showed comparable birth weights, weight gain, a viability index (postnatal d 4) for all groups of > or = 97%, and no histopathological changes. In the dams, there were no significant differences in the mean numbers of corpora lutea, implantation sites, and resorptions recorded at necropsy. In the males, the only remarkable findings at necropsy were a small right epididymis and testis seen in one mid-dose male and an abscess on the right epididymis of a high-dose male. In both cases, the dams that had been bred to these males produced normal litters. There were no test material-related microscopic changes observed in the testes and epididymis of the F0 male rats or ovaries of the F0 female rats exposed to LAND. Under the conditions of this experiment, the no-observed-adverse-effect level (NOAEL) for LAND via inhalation in rats is established at greater than 24.7 g/m3 (analytical concentration).

No such thing as 'uncomplicated bereavement' for patients in rehabilitation.

PURPOSE: This review aims to: (1) discuss the reasons for the limited focus in the literature on the loss experiences of patients in rehabilitation; (2) highlight the importance of increasing our understanding of the loss reactions of these patients; and (3) offer suggestions for appropriate incorporation of bereavement issues into clinical practice and research. METHOD: The authors review articles and books from several disciplines to reveal and provide suggestions for overcoming limitations in application of current bereavement theory and practice with disabled populations. RESULTS: The paper identifies problems with the descriptive and diagnostic language' of bereavement, a lack of empirical support for popular theory and assumptions about the grieving process and bereaved persons, disagreement among bereavement and rehabilitation clinicians on most appropriate interventions for facilitating adjustment, and compelling reasons to focus on bereavement issues with the disabled patient. CONCLUSIONS: The review reveals the need to clarify loss issues and terminology, develop appropriate measures of the loss experiences of patients with disability, identify variables affecting the process and outcome of grieving in this population, develop guiding theory and select interventions that meet the needs of these patients.

Region-specific loss of alpha 1-adrenergic receptors in rat brain with aging: a quantitative autoradiographic study.

The effects of aging on the density and affinity of alpha 1-adrenergic receptors (alpha 1-ARs) were studied in several circumscribed areas of the Fischer 344 male rat brain. Computer-assisted quantitative autoradiography was used to analyze saturation binding isotherms of [125I]BE-2254, a selective alpha 1-AR antagonist. Significant decreases in receptor density of 15 and 29% were observed in the thalamus at 16-18 and 24-28 months of age, respectively, when compared to 3-4-month-old controls. Progressive declines in receptor density of 24 and 44% were also found in the olfactory tubercle. In the cerebral cortex, a significant 26% loss in receptors occurred only in the oldest age group. No changes were found in any of the other brain areas investigated, including the cerebellum, brainstem, caudate-putamen, and several subregional areas of the hippocampal formation. Kd values ranged from 12 +/- 1.8 pM in the brainstem to 23 +/- 1.6 pM in the thalamus and were not affected by aging in any area examined. It is concluded that the density of alpha 1-ARs in the Fischer 344 rat brain is diminished with aging in a region-specific manner and that loss of these receptors may account for age-related functional deficits only in a few brain areas.

Decreased efficacy of inositol 1,4,5-trisphosphate to elicit calcium mobilization from cerebrocortical microsomes of aged rats.

The effects of aging on the ability of brain microsomes to sequester calcium in response to ATP stimulation and to release calcium in response to inositol 1,4,5-trisphosphate (IP3) stimulation were examined. Calcium uptake and release were compared in microsomal preparations from the cerebral cortex, hippocampus, thalamus, and cerebellum of 3-, 16-, and 28-month-old male Fischer 344 rats. No age-related differences were found in the ability of brain microsomes to sequester calcium in response to ATP stimulation. A maximally effective concentration of IP3 (1 microM) released approximately 30% of the calcium sequestered by microsomes. This was observed in all brain regions and age groups studied except in the cerebral cortex, where the amount of calcium released by IP3 was reduced by 50% in the oldest age group. Concentration-response curves for IP3 in this brain region from 3- and 28-month-old rats confirmed that the maximally effective concentrations, the EC50 values, and the Hill coefficients did not differ with aging. These data indicate that the efficacy of IP3 is selectively diminished in the cerebral cortex of aged rats and that this age-related change may contribute to the attenuated responsiveness of neurons in this brain region to activation by phosphoinositide-coupled receptors.

Use of antiepileptics in traumatic brain injury: a review for psychiatrists.

In recent years, the number of new antiepileptic agents has been growing, as have the potential applications. Traumatic brain injury (TBI) patients often present with behavioral disturbances that may be amenable to treatment with antiepileptic drugs. These conditions include bipolar disorder, as well as posttraumatic seizures and agitation. We review treatment of these three conditions with newer agents, as well as past literature on treatment with older antiepileptic drugs. We also review the pharmacology of newer antiepileptic drugs and summarize reports that indicate possible utility in the TBI population. Although there is a paucity of evidence for brain injury patients specifically, experience with similar groups suggests that these drugs may be useful. Further trials are indicated to clarify the role of the new antiepileptic agents, which may offer more tolerable side effect profiles than do current treatments.

Propafenone interacts stereoselectively with beta 1- and beta 2-adrenergic receptors.

In order to determine whether the new antiarrhythmic agent propafenone interacts stereoselectively with beta-adrenergic receptors, the potencies of both the (-) and (+) isomers were determined using in vitro binding assays. (-)-Propafenone was the more potent isomer and competed with 125I-pindolol in a simple manner in both rat cerebral cortical and cerebellar membranes with Ki values of 32 +/- 1.7 and 77 +/- 5.8 nM, respectively. In contrast, competition curves for (+)-propafenone in the same tissues were more complex and revealed two binding sites with affinities 10- to 75-fold less potent than those for (-)-propafenone. Moreover, the (+)-propafenone was found by high performance liquid chromatography (HPLC) analysis to be contaminated with 3% of the more potent (-)-isomer; this contamination accounted for most of the apparent activity of the (+)-propafenone. These data suggest that interactions of propafenone with both beta 1- and beta 2-receptors are markedly stereoselective for the (-) isomer. It is possible that beta-adrenergic receptor blockade by the (-) isomer may be responsible for some of the adverse clinical effects that have been reported with propafenone therapy.

Predicting "charge outliers" after spinal cord injury: a multicenter analysis of demographics, injury characteristics, outcomes, and rehabilitation charges.

OBJECTIVE: To describe the distribution of charges, to distinguish between "charge outliers" and nonoutliers, and to identify a model that uses demographics and injury characteristics to predict charge outlier status in individuals with spinal cord injury (SCI). DESIGN: Retrospective data analysis of patients admitted to 24 acute inpatient rehabilitation national Spinal Cord Injury Model Systems centers. Statistical analysis, including proportions, means, and standard deviations (SDs), were compiled for the following variables: demographic and injury information, rehabilitation charges, medical complications, associated injuries, and surgical procedures. SETTING: Tertiary, university medical centers participating in the National Institute on Disability and Rehabilitation Research's SCI Model Systems project. PARTICIPANTS: A total of 13,392 patients who were admitted to 24 acute, intensive, interdisciplinary rehabilitation settings after traumatic SCI between November 1972 and August 1996. MAIN OUTCOME MEASURES: Statistical data analysis was used to determine significance between charge outliers and nonoutliers on the basis of demographic, injury characteristics, and clinical factors. Outliers, under the current diagnostic-related group system, are defined as cases in which lengths of stay exceed the mean by the lesser of 20 days or 1.94 SDs. RESULTS: Statistically significant differences were found between SCI charge outliers and nonoutliers based on ethnicity, education, employment, level of injury, American Spinal Injury Association impairment classification, and sponsor of hospitalization. On average, outliers were 4 years older than nonoutliers, and tended to have more associated injuries, pressure ulcers, surgical procedures, and medical complications. A forward-conditional stepwise multiple logistic regression analysis was used to confirm univariate analysis and to predict the presence or absence of outliers based on the predictor variables. A model for the prediction of SCI charge outlier status was defined. CONCLUSIONS: SCI charge outliers are most likely to be retired, insured, have high cervical level injuries, and be educated beyond high school. Improved treatment efficiency serves as a means of cost reduction and is a reason to identify outlier characteristics.

Functional outcome for African Americans and Hispanics treated at a traumatic brain injury model systems centre.

OBJECTIVE: To describe the demographics, incidence and functional outcome for African Americans and Hispanics treated at a traumatic brain injury (TBI) model systems centre. DESIGN: Retrospective data analysis of patients admitted to an acute inpatient rehabilitation national TBI model systems centre. SETTING: A tertiary care university medical centre participating in the NIDRR Traumatic Brain Injury Model Systems project. SUBJECTS: Eighty-seven patients with TBI admitted to a Model Systems acute intensive interdisciplinary rehabilitation setting between 1989-1999. Information was extracted from the National TBI Model Systems data base for demographics such as age, race, education, gender, marital and employment status, sponsorship, injury aetiology and severity. OUTCOME MEASURES: Functional outcome was determined using the Functional Independence Measure (FIM), and the Disability Rating Scale (DRS) at the time of admission and discharge. RESULTS: Descriptive statistics were completed using SPSS. African American (94.3%) and Hispanic (5.7%) patients were injured most often as a result of motor vehicle accidents (48.8%). Males comprised 86.2% of this population, which had an average age of 34.5 years (SD = 13.1). On admission, average GCS score was 7.8 (SD = 3.6), average DRS was 13.5 (SD = 5.8), and average FIM total score was 49.8 (SD = 26.5). Average length of unconsciousness was 5.2 days (SD = 27.9), while average length of post-traumatic amnesia was 41.9 days (SD = 59.3). At the time of injury, 78.2% of the patients were not married. The majority of patients (97.7%) had private residences and 88.5% returned to their original home. Most patients had at least a high school education or passed a high school equivalent exam (49.4%) and were employed (70.1%) at the time of injury. Only 7% of the patients had a history of prior TBI. With regard to substance use, only 34.2% of patients reported pre-morbid illicit drug use. However, 50.5% met criteria for heavy or moderate alcohol use rates. Only 35.6% of patients reported a pre-morbid history of arrests, with the average number of arrests equal to 4.5 (SD = 10.2). Within this population, the number of drug or alcohol related arrests was 4.8 (SD = 13.5). CONCLUSIONS: Unmarried African American males, with an average age of 35 years, predominated at this institution. The primary mechanism of injury was motor vehicle accidents. The majority of patients had, at least, a high school education or passed an equivalency exam, were employed at the time of their injury and were discharged to their prior private residence. While half of the patients met criteria for moderate-to-heavy alcohol consumption, only one-third of the patients reported a history of pre-morbid illicit drug use. This descriptive analysis supports the need for further investigation of minority populations that sustain TBI and will enhance the accuracy of implications that minority status may have on functional outcome.

Effect of aging on alpha-1 adrenergic stimulation of phosphoinositide hydrolysis in various regions of rat brain.

The effects of aging were examined on the ability of alpha-1 adrenergic receptor agonists to stimulate phosphoinositide hydrolysis in three brain regions. Tissue minces of thalamus, cerebral cortex and hippocampus from 3-, 18- and 28-month-old male Fischer 344 rats were prelabeled with [3H]myoinositol. Exposure of these prelabeled minces to phenylephrine and (-)-norepinephrine revealed that accumulation of [3H]inositol phosphates was selectively reduced by 20 to 30% in the thalamus and cerebral cortex of the oldest age group. Analysis of concentration-response and competition binding curves indicated that this decrease was due to diminished agonist efficacy rather than diminished receptor affinity. The reduction in responsiveness to phenylephrine and (-)-norepinephrine in the cerebral cortex and the lack of any changes in the hippocampus parallel previously reported changes in the density of alpha-1 adrenergic receptors with aging. These data indicate that the ability of alpha-1 adrenergic receptor agonists to stimulate phosphoinositide hydrolysis is reduced in some, but not all, brain regions of aged Fischer 344 rats.

Determination of morantel-related residues in bovine milk by electron capture gas chromatography.

A gas chromatographic assay was developed to determine major residues of morantel in bovine milk over a range that is suitable for monitoring residues of the drug. The method is based on hydrolysis of the N-methyl-tetrahydropyrimidine portion of morantel and its metabolites to N-methyl-1,3-propanediamine, and converting the diamine to an N,N-bis-(2-nitro-4-trifluoromethylphenyl) derivative. The addition of an internal standard, the N-desmethyl-N-ethyl homolog of pyrantel, to the milk sample circumvents any potential problem that could arise from variable reaction yields, and eliminates the true recovery as a factor affecting the accuracy and precision of the procedure. The concentrations of the derivatives are determined by pulsed electron capture gas chromatography over a linear dynamic range that is equivalent to 12.5-50 ppb morantel. The method was evaluated at the 0, 12.5, 25, and 50 ppb levels in fortified bovine milk, and in a withdrawal sample containing physiologically incurred morantel residues. Mean values of 14 +/- 1.7, 24 +/- 3.7, and 47 +/- 6.9 were found for the fortified samples, approximately 3 ppb for control milk, and 16 +/- 1.7 ppb for the withdrawal sample.