Chiari I malformation with acute neurological deficit after craniocervical trauma: Case report, imaging, and anatomic considerations

Background:

In patients with Chiari I malformation (CMI), the occurrence of acute neurologic deficit after craniocervical trauma is rare. However, the pathologic potential of exacerbating anatomic overcrowding of the posterior fossa has immense clinical consequences and prompt recognition is essential.

Case Description:

This case study describes a 41-year-old male who sustained a single blow to the face, fell, and struck the occiput. On admission, neurological examination revealed a profound paraparesis, upper extremity diplegia, a C4 sensory level and apnea that required intubation. On arrival, computerized axial tomography of the head showed a small amount of contrecoup left frontal traumatic subarachnoid hemorrhage. Magnetic resonance imaging (MRI) performed 19 h after admission was negative except for the presence of a CMI. He acutely declined on post injury day 2, prompting emergent decompression of the posterior fossa where anatomic overcrowding was observed. At 19 weeks post injury, his motor function had significantly improved.

Conclusion:

The constellation of severe neurologic deficit in patients with CMI after relatively minor craniocervical trauma has been previously described. In our patient, neurologic deficit disproportionate to the mechanism of injury was observed and likely in part attributed to the presence of a Chiari malformation. Unfortunately, MRI has not yet been able to clearly define the underlying pathoanatomy, help understand the mechanism of injury, and delineate when operative intervention is indicated in these patients. Here, we review similar cases from the literature, examine findings on MRI, and evaluate mechanisms of injury following craniocervical trauma in patients with CMI to help clarify these questions.

Entry kinetics and cell-cell transmission of surface-bound retroviral vector particles

BACKGROUND

Transduction with recombinant HIV-1 derived lentivirus vectors is a multi-step process initiated by surface attachment and subsequent receptor-directed uptake into the target cell. We previously reported the retention of vesicular stomatitis virus G protein pseudotyped particles on murine progenitor cells and their delayed cell-cell transfer.

METHODS

To examine the underlying mechanism in more detail, we used a combination of approaches focused on investigating the role of receptor-independent factors in modulating attachment.

RESULTS

The investigation of synchronized transduction reveals cell-type specific rates of vector particle clearance with substantial delays during particle entry into murine hematopoietic progenitor cells. The observed uptake kinetics from the surface of the 1 degrees cell correlate inversely with the magnitude of transfer to 2 degrees targets, corresponding with our initial observation of preferential cell-cell transfer in the context of brief vector exposures. We further demonstrate that vector particle entry into cells is associated with the cell-type specific abundance of extracellular matrix fibronectin. Residual particle-extracellular fibronectin matrix binding and 2 degrees transfer can be competitively disrupted by heparin exposure without affecting murine progenitor homing and repopulation.

CONCLUSIONS

Although cellular attachment factors, including fibronectin, aid gene transfer by colocalizing particles to cells and disfavoring early dissociation from targets, they also appear to stabilize particles on the cell surface. The present study highlights the inadvertent consequences for cell entry and cell-cell transfer.

Incorporating serotypes into family based association studies using the MFG test

Family based association tests are widely used to detect genetic effects. The focus of this paper is the maternal-fetal genotype (MFG) incompatibility test, a family based association test which can be used to detect genetic effects that contribute to disease, including alleles in the child that increase disease risk, maternal alleles that increase disease risk in the child, and maternal-fetal genotype incompatibilities. Consideration of incomplete data resulting from using serotypes could expand the power of the MFG test for detecting genetic effects. Serotypes may be all that are available in certain families, or preferred because of convenience or low cost, and thus a modification of the MFG test will allow optimal use of such data. The modified MFG likelihood can accommodate the incomplete data that result from using serotypes rather than the corresponding codominant genotypes. The modified MFG test was evaluated with serotypes and genotypes from families with members affected with schizophrenia. In addition, simulation studies were performed. Results of the data analyses and simulation studies showed that serotypes can be used to augment genotypes within a sample, to increase power to detect effects when the candidate gene produces serotypes.

A multivariate approach to affected-sib-pair analysis using highly dense molecular maps

A multivariate approach to affected-sib-pair analyses was performed to localize disease-susceptibility genes with a minimum number of type I errors (false positives). Using 1,155 independent affected sib pairs extracted from Problem 2A of the GAW10 data set, we were able to localize major genes (MG) 1 and 2. Using 30% of the affected-sib-pair sample (N = 337) we were able to localize MG1. False positives were not detected in either of these samples.

Evaluating the simplified Conjoint Expected Risk model: comparing the use of objective and subjective information

The simplified Conjoint Expected Risk (CER) model by Holtgrave and Weber posits that perceived risk is a linear combination of the subjective judgments of the probabilities of harm, benefit, and status quo, and the expected harm and benefit of an activity. It modifies Luce and Weber's original CER model--that uses objective information to evaluate financial gambles--to accommodate activities such as health/technology activities where values of the model variables are subjective. If the simplified model is a valid modification of the original model, its performance should not be sensitive to the use of subjective information. However, because people may evaluate information differently when objective information is provided to them than when they generate information on their own, the performance of the simplified CER model may not be robust to the source of model-variable information. We compared the use of objective and subjective information, and results indicate that the estimates of the simplified CER model parameters and the proportion of variance in risk judgments accounted for by the model are similar under these two conditions. Thus, the simplified CER model is viable with activities for which harm and benefit information is subjective.

Life-threatening interactions between HIV-1 protease inhibitors and the illicit drugs MDMA and gamma-hydroxybutyrate

Human immunodeficiency virus 1 (HIV-1) protease inhibitors have dramatically reduced the morbidity and mortality due to HIV-1 infection. However, most of these antiretrovirals are also potent inhibitors (and occasionally inducers) of hepatic and intestinal cytochrome P450 systems and, therefore, have the potential to alter the elimination of any substance that utilizes these metabolic pathways. We describe a patient infected with HIV-1 who was treated with ritonavir and saquinavir and then experienced a prolonged effect from a small dose of methylenedioxymetamphetamine (MDMA or ecstacy) and a nearly fatal reaction from a small dose of gamma-hydroxybutyrate (GHB). We also discuss the potential for HIV-1 protease inhibitors to alter the metabolism of other abusable prescribed and illicit substances.

Evidence that the dopamine D4 receptor is a susceptibility gene in attention deficit hyperactivity disorder

Attention deficit hyperactivity disorder (ADHD) is a common neurobehavioral problem afflicting 5-10% of children and adolescents and persisting into adulthood in 30-50% or more of cases. Family, twin, and adoption studies suggest genetic factors contribute to ADHD and symptoms of inattention, impulsivity, and hyperactivity. Because stimulant intervention is effective in reducing ADHD symptoms in about 70-80% of cases, molecular genetic investigations of genes involved in dopamine regulation are currently underway by many groups. In a case control study of the dopamine D4 receptor gene (DRD4) and ADHD, La Hoste and colleagues found an increase of a 7-repeat variant of a 48-bp VNTR in exon 3 among ADHD subjects compared to controls. Swanson and colleagues replicated this finding in a sample of 52 ADHD probands and their biological parents using a haplotype relative risk analysis. Here, we describe linkage investigations of the VNTR and ADHD in affected sibling pair (ASP) families and singleton families using both the transmission disequilibrium test (TDT) and a mean test of identity-by-descent (IBD) sharing. Using the TDT in the total sample, the 7 allele is differentially transmitted to ADHD children (P = 0.03) while the mean test revealed no evidence of increased IBD sharing among ASPs. In the current sample, the 7 allele attributes a 1.5-fold risk for developing ADHD over non-carriers of the allele estimated under a model described by Risch and Merikangas.

A general statistical model for detecting complex-trait loci by using affected relative pairs in a genome search

Scanning of the human genome by use of affected relative pairs and dense sets of highly polymorphic markers or by emerging techniques such as genomic mismatch scanning. (GMS) is making it possible to identify the genetic etiology of a disease through detection of susceptibility loci. We present a general statistical model and test to detect disease genes, using affected relative pairs and either markers or GMS technologies in a genome search. There are an exact test and large-sample normal approximation that control for the elevated probability of false detection of linkage in a genome search. The approach can be used to determine the sample size needed to obtain a prespecified power to detect a disease gene in the presence of etiologic heterogeneity for a single class or mixture of relative classes, with any number of markers, or clones, markers PIC values, or mapping function. The approach is used to examine differences in performance of markers and GMS technologies in a common statistical framework and to provide practical information for designing studies of complex traits.

Commingling analysis of memory performance in offspring of Alzheimer patients

Dementia of the Alzheimer type (DAT) is a neurodegenerative disorder which afflicts approximately 3% of the population. Genetic influences are indicated from twin and family studies although genetic heterogeneity has been suggested from both pedigree analyses and linkage investigations. Autosomal dominant inheritance with age-dependent penetrance has been suggested in at least some families with DAT. In the present investigation, we examine memory and nonmemory task performance in 106 asymptomatic offspring (mean age 40.6 years) of 54 DAT probands. Intraclass sibling correlations revealed little evidence of sibling similarity for performance on three memory tasks which have been reported to be relatively sensitive to the memory losses accompanying DAT. Subsequent investigations of the distributions of the cognitive task scores in the offspring revealed evidence for a commingling of two distributions for the three memory tasks but not for the nonmemory measures. These findings are consistent with a hypothesis that these distributions reflect genotypic subgroups, carriers, and noncarriers, of a presumed DAT gene.

Interregional elderly migration and population redistribution in four industrialized countries. A comparative analysis

Though differing in cultures, languages, and socioeconomic attributes, the industrialized nations of the world share a common characteristic: relatively low fertility levels and relatively high proportions of elderly people. These elderly persons are not spread uniformly across their national territories; they exhibit distinct population geographies. This article examines the elderly migration and population redistribution process in four industrialized countries, identifies their principal retirement regions, and analyzes the sources of regional elderly population growth in these regions. It concludes that the United Kingdom and the United States are approaching the final stages of their "elderly mobility transition," whereas Japan is only entering the first stage, with Italy occupying a position somewhere in between.

Effects of hypothyroidism and hyperthyroidism on GDP binding to brown-adipocyte mitochondria from rats

1. Rats were made hypothyroid by giving them a low-iodine diet with propylthiouracil for 4 weeks, or were made hyperthyroid by injection with tri-iodothyronine (T3) over a 3-day period. 2. Brown adipocytes were isolated from the interscapular depots of these animals or from their euthyroid controls, followed by isolation of mitochondria from the cells. 3. Relative to cell DNA content, hypothyroidism decreased the maximum binding (Bmax.) of [3H]GDP to mitochondria by 50%. T3 treatment increased binding by 37%. 4. These findings, which are discussed in relation to previously observed changes in brown adipose tissue after alteration of thyroid status, suggest that mitochondrial uncoupling for thermogenesis is less or more effective in hypothyroidism or hyperthyroidism respectively.

Estimating the size of closed populations using inverse multiple-recapture sampling

A log-linear model for estimating the size of a closed population is defined for inverse multiple-recapture sampling with dependent samples. Efficient estimators of the log-linear model parameters and the population size are obtained by the method of minimum chi-square. A chi-square test of the general linear hypothesis regarding the log-linear model parameters is defined.

Conditional factors of maturing out: personal resources and preaddiction sociopathy

The study continues exploration of the conditional nature of the process of maturing out of narcotics addiction over time. It tests hypotheses about the relationship of selected personal resource/sociodemographic variables (including ethnicity and employability) and preaddiction sociopathy characteristics to maturing out. Hypotheses were tested using log-linear models on data from the California Civil Addict Program. Results suggest that while the process of maturing out over time is not substantially different depending upon level of preaddiction sociopathy or ethnicity, the process may be influenced by levels of other personal resource characteristics.

The impact of raising the minimum drinking age on driver fatalities

Time series analysis was used to obtain statistical tests of the impact of raising the drinking age on monthly driver fatalities in Illinois, Michigan, and Massachusetts. A control series design permitted comparison between younger drivers (21 or less years) and older drivers (25 and older) within states where the minimum drinking age was raised. Since the two groups share the same driving conditions, it was important to demonstrate that any reduction in fatalities was limited to the young age group within which the drinking age change occurred. In addition, control states were selected to permit a comparison between driver fatalities of the young age group (21 or less) in states with the law change and young drivers in states without the law change. Significant immediate reductions in fatalities among 21 and younger drivers in Illinois and Michigan were observed after these states raised their minimum drinking age. No significant reductions in any control series were observed. A linear decrease in young driver fatalities was observed after the drinking age was raised in Massachusetts. There was also a significant linear decrease in young driver fatalities in the Connecticut control series, perhaps due to increasing awareness among young drivers of the dangers of drinking and driving.

Effect of adenosine deaminase, N6-phenylisopropyladenosine and hypothyroidism on the responsiveness of rat brown adipocytes to noradrenaline

Adenosine deaminase (1 unit/ml) potentiated the lipolytic action of noradrenaline in adipocytes isolated from brown adipose tissue of 1- and 6-week-old rats by decreasing the EC50 (concn. giving 50% of maximal effect) for noradrenaline by 3-4-fold. With cells from neonatal rabbit tissue, adenosine deaminase only had a small, non-significant, effect on the EC50 for noradrenaline. Lipolysis in rat brown adipocytes was inhibited by low concentrations of N6-phenylisopropyladenosine (PIA). Rabbit cells were far less sensitive to PIA. PIA, prostaglandin E1 and nicotinate all inhibited noradrenaline-stimulated respiration in rat brown adipocytes. Hypothyroidism diminished the maximum response of respiration and lipolysis to noradrenaline in rat cells and increased the EC50 for noradrenaline. Responsiveness of lipolysis to noradrenaline was particularly decreased in hypothyroidism and was partially restored by addition of adenosine deaminase. Lipolysis in cells from hypothyroid rats was more sensitive to the anti-lipolytic action of PIA. Bordetella pertussis toxin increased lipolysis in the presence of PIA, suggesting an involvement of the Ni guanine-nucleotide-binding protein in the control of brown-adipocyte metabolism.

An empirical study of maturing out: conditional factors

Using data from the California Civil Addict Program, the study tested hypotheses about the possible conditional nature of the process of maturing out of heroin addiction. Hypotheses were tested in a five-way contingency table using the log-linear model. Results show that maturing out of addiction with increasing age is inhibited by high levels of involvement in crime and drug dealing.

Some extensions of a linear model for categorical variables

The Grizzle-Starmer-Koch (GSK) model is extended to include the traditional log-linear model and a general class of Poisson and conditional Poisson distributions. Estimators of the model parameters are defined under general exact and stochastic linear constraints.

MMPI correlates of relatively localized brain damage

Examined the MMPI correlates of relatively localized brain damage classified along dimensions of laterality and caudality. Forty patients with lateralized lesions that involved anterior or posterior cerebral areas were studied. Based on a multivariate analysis of variance, results revealed significant differences in MMPI profiles between left hemisphere and right hemisphere lesion groups. The MMPI profile for the left hemisphere lesion group is well within the normal range; the right hemisphere lesion group is beyond normal limits, primarily on scales 8 and 2. Several issues are discussed in an effort to integrate these findings with previous studies.

The private practice nurse practitioner

Nurse practitioners have endless possibilities for innovative practice. Deciding on provision of independent practice, suggestions for implementation and service, possible barriers, and solutions are discussed. Future directions for services are outlined.

Construct validity of heroin abuse estimators

The construct validity of two methodologically unrelated procedures for estimating the prevalence of heroin abuse was studied using a covariance structure model-fitting approach. A factor analytic estimation procedure and a log-linear-based capture-recapture method of estimation were simultaneously applied to 24 major metropolitan areas of the nation. A test of the construct validity of these procedures for estimating the prevalence of heroin abuse was carried out in the context of structural equation models where the results of the two methods were compared directly.

Estimating the size of subpopulations of heroin users: applications of log-linear models to capture/recapture sampling

This article reviews two of the major methodologies applied to estimation of the number of heroin abusers: survey research methods and the capture/recapture technique. The main focus of the paper is to show the flexibility of the capture/recapture approach in handling not only the dependence of samples of heroin users but also the nonhomogeneity of sampling probabilities, allowing estimation in populations which are mixtures of qualitatively different heroin user types. Models with these features are illustrated using both simulated and real heroin abuse data.

Communication deviance in the families of schizophrenics: a comment on the misuse of analysis of covariance

Serious contradictions in recent research programs concerning communication anomalies in parents of schizophrenics have been generated by invalid statistical analyses. The method of analysis used, the analysis of covariance, can lead to erroneous conclusions in the context of these studies, and thus, other means must be sought for bringing these important research programs into common focus.

Common Misconceptions Concerning The Analysis Of Covariance

Four misconceptions about the requirements for proper use of analysis of covariance (ANCOVA) are examined by means of Monte Carlo simulation. Conclusions are that ANCOVA does not require covariates to be measured without error, that ANCOVA can be used effectively to adjust for initial group differences that result from nonrandom assignment which is dependent on observed covariate scores, that ANCOVA does not provide unbiased estimates of true treatment effects where initial group differences are due to nonrandom assignment which is dependent on the true latent covariable if the covariate contains measurement error, and that ANCOVA requires no assumption concerning the equality of within-groups and between-groups regression. Where treatments actually influence covariate scores, the hypothesis tested by ANCOVA concerns a weighted combination of effects on covariate and dependent variables.

Verbal and performance IQ for discrimination among psychiatric diagnostic groups

WAIS Verbal and Performance IQ scores were obtained from medical records of 500 psychiatric inpatients recently admitted to a large university hospital. With a subsample of the original 500 patients for whom there was diagnostic agreement between two independent clinicians, a multivariate analysis of variance was carried out to determine the extent to which the Verbal and Performance scores discriminated among eight diagnostic categories into which patients were classified. In the multivariate ANOVA, statistical techniques were employed to control for concomitant background variation that otherwise might have been confounded with true diagnostic group differences in Verbal and Performance IQ. Although mentally retarded and organic brain syndrome patients could be distinguished significantly from other diagnostic groups on the basis of their lower total IQ scores, the data did not support the persistent clinical belief that functional psychiatric disorders differed in the WAIS measurement space.

The dependence of psychiatric diagnosis on psychological assessment

This study examined the dependence of 500 inpatient psychiatric diagnoses on the results of standard psychological assessment procedures. A 43% agreement was found between psychological test findings and psychiatric discharge diagnoses. While this level of agreeement is greater than chance, it suggests that psychological test results are not of value in more than one-half of the cases investigated. Specific diagnostic discrepancies between clinical and psychological diagnostic results were noted, and several explanations for these differences were offered.

Patterns of symptom change in anxious depressed outpatients treated with different drugs

Patients with mixtures of anxiety and depressive mood of rather modest degree constitute a majority in the psychiatric outpatient population. Drug treatments are employed to produce symptomatic relief. In this study, thirteen commonly used psychotherapeutic drugs were compared for efficacy in producing change in symptoms of anxiety, depressive mood, and psychomotor activation level in this most common type of psychiatric clinic patient. The drugs were found to differ in relative effect on anxiety and depressive mood. Paradoxically, the major and minor tranquilizers produced greater effect on depressive mood than anxiety, while the more sedative of the tricyclic antidepressants produced relatively greater effect on anxiety. Within each of the three major drug classes, the more sedative members of the class tended to have relatively greater effect on anxiety and the less sedative tended to have relatively greater effect on depressive mood components of the symptom picture.

An Approximate Confidence Interval for Maximum Coefficient Alpha

An approximate confidence interval is developed for the maximum coefficient alpha reliability of a scale where the scale is considered fixed an persons are sampled.