Mid-p confidence intervals for the poisson expectation

Conventionally a confidence interval (CI) for the standardized mortality ratio is set using the conservative CI for a Poisson expectation, μ. Employing the mid-P argument we present alternative CIs that are shorter than the conventional ones. The mid-P intervals do not guarantee the nominal confidence level, but the true coverage probability is only lower than the nominal level for a few short ranges of μ. The implications for mid-P confidence intervals of various proposed definitions of two-sided tests for discrete data are discussed.     

Childhood Malignant Thymoma: Clinical, Therapeutic, and Immunohistochemical Considerations

Malignant thymomas are among the least common mediastinal tumors in the pediatric age group. Thymomas are considered malignant on the basis of macroscopic and microscopic invasiveness. As only 20 well-documented cases involving children have been reported in the literature, the pattern of responsiveness to therapy and the value of prognostic signs is obscure. Two cases of malignant pediatric thymomas are reported with pathognomonic histoimmunological features of aggressive thymoma. One was cured, with a follow-up of 70 months, and one died while on therapy. Analysis of the histological features and the immunoperoxidase staining displays the complexity of pediatric thymomas and the inability to prognosticate the outcome, respectively.     

Frequent attendance at religious services and mortality over 28 years.

OBJECTIVES: This study analyzed the long-term association between religious attendance and mortality to determine whether the association is explained by improvements in health practices and social connections for frequent attenders. METHODS: The association between frequent attendance and mortality over 28 years for 5286 Alameda Country Study respondents was examined. Logistic regression models analyzed associations between attendance and subsequent improvements in health practices and social connections. RESULTS: Frequent attenders had lower mortality rates than infrequent attenders (relative hazard [RH] = 0.64;95% confidence interval [CI] = 0.53,0.77). Results were stronger for females. Health adjustments had little impact, but adjustments for social connections and health practices reduced the relationship (RH = 0.77; 95% CI = 0.64, 0.93). During follow-up, frequent attenders were more likely to stop smoking, increase exercising, increase social contacts, and stay married. CONCLUSIONS: Lower mortality rates for frequent religious attenders are partly explained by improved health practices, increased social contacts, and more stable marriages occurring in conjunction with attendance. The mechanisms by which these changes occur have broad intervention implications.     

Sonography of hypertrophic pyloric stenosis: frequency and cause of nonuniform echogenicity of the thickened pyloric muscle.

In hypertrophic pyloric stenosis, the muscle is typically described as hypoechoic on sonography. However, we have frequently noted a nonuniform pattern; the pyloric muscle seen in the transverse plane is more echogenic in the near and far fields and less echogenic on the sides. The muscle also appears almost as echogenic as the liver on midline longitudinal sonograms. To establish the frequency of these findings, we reviewed the sonograms of 71 infants with hypertrophic pyloric stenosis. The muscle was imaged directly during surgery in three patients. In an in vitro experiment, muscle arranged to stimulate the pyloric ring was scanned in a water bath. Then, using two sections of muscle, we compared the echogenicity when scanning in a plane perpendicular to the long axis of the muscle fibers with that seen with the beam parallel to the long axis of the muscle fibers. In the transverse plane, nonuniform echogenicity of the pyloric muscle was seen in 59 (98%) of 60 patients. In the midline longitudinal plane, the muscle was equal to or slightly less echogenic than the liver in all patients. Both the in vivo and in vitro studies show that the echogenicity varies with the relationship of the ultrasound beam to the orientation of the circular muscle fibers; this phenomenon is known as the anisotropic effect. Our results show that nonuniform echogenicity of the hypertrophied pyloric muscle is a characteristic sonographic finding caused by the anisotropic effect, which is related to the orientation of the ultrasound beam with respect to the circular fibers of the pyloric muscle.     

Direct detection of Molluscum contagiosum virus in clinical specimens by in situ hybridization using biotinylated probe.

Molluscum contagiosum virus (MCV) is an unclassified poxvirus which has recently become recognized as causing a major sexually transmitted disease. At present no assay is available for specific detection of MCV because the virus cannot be serially propagated in cell culture. Since MCV produces an abortive, limited growth with some cytopathic effect in certain cell lines, we were able to develop an in situ hybridization assay for detection of MCV genome in clinical specimens. Human fetal diploid lung cell monolayers were infected with clinical specimens, and after proper incubation and fixation in paraformaldehyde, hybridization was performed under full stringency conditions with a molecularly cloned biotinylated probe. Only MCV infected cells showed homology to the MCV probe with a purple-brown cytoplasmic staining. Additionally, we have described an in situ hybridization assay for direct detection of MCV genome in formalin-fixed, paraffin-embedded biopsies. Characteristic intracytoplasmic Molluscum bodies (Henderson-Paterson bodies) were detected in stratum spinosum cells of the epidermis. Striking staining similarities have been observed between in situ hybridization and haematoxylin-eosin cytostaining. These procedures are the first successful identification of MCV genome in clinical samples by molecular hybridization, with sensitivity and specificity equal to or greater than electron microscopy.     

Physiological analysis of motor reorganization following lower limb amputation.

It is now known that amputation results in reorganization of central motor pathways, but the mechanism for the changes is unclear. One possibility is alteration of the excitability of the alpha motoneurons. We studied motor reorganization and excitability of alpha motoneurons to Ia input in 6 subjects with unilateral lower limb amputation. A Cadwell MES-10 stimulator was used to deliver transcranial magnetic stimuli through a circular coil centered on the sagittal axis 4 cm anterior to Cz and through an 8-shaped coil positioned over scalp locations 1 cm apart along the coronal axis. Surface EMG was recorded bilaterally from quadriceps femoris, the first muscle immediately proximal to the site of amputation. Excitability of the spinal alpha motoneuron pool to Ia afferents was assessed by determining the ratio of the maximal H reflex to the maximal M response (H/M ratio) elicited in the quadriceps femoris. Stimuli of equal intensity delivered to optimal scalp positions recruited a larger percentage of the alpha motoneuron pool in muscles ipsilateral to the stump than in those contralateral to the stump (P less than 0.01). Mean onset latencies of motor evoked potentials were shorter in ipsilateral muscles than in contralateral muscles (P less than 0.01). Muscles ipsilateral to the stump showed a trend toward activation from a larger number of scalp positions than those contralateral to the stump (P = 0.06). There was no difference in the quadriceps H/M ratios (7.2% ipsilateral vs. 10.9% contralateral). The absence of changes in the excitability of the alpha motoneuron pool in the presence of motor reorganization targeting muscles proximal to the stump suggests that reorganization occurs proximal to the alpha motoneuron level.     

Fever associated with teething.

A relationship between teething and fever was sought by examining mothers' reports of the 20 days before the eruption of the first tooth in 46 healthy infants. Twenty infants had a fever of greater than 37.5 degrees C on day 0 compared with seven infants (or fewer) from day 19 to day 4. The danger of attributing fever to teething is emphasised.     

Spatial learning deficits in adult children of alcoholic parents

This study investigated whether the visuospatial deficits displayed by chronic alcoholics are present in persons at risk for alcoholism. Participants were 34 matched social drinkers, half of whom were children of alcoholic parents and half of whom had no family alcoholism history. Ss with a family history of alcoholism displayed visuospatial learning that was significantly poorer than that displayed by Ss with no family alcoholism history. The learning patterns displayed by those with a family alcoholism history were similar to those displayed by previously studied detoxified alcoholics and young children of alcoholics using a similar learning task. Data suggest that visuospatial learning deficits may reflect an antecedent to rather than a consequence of chronic alcohol abuse.