High-resolution magnetic resonance imaging demonstrates abnormalities of motor nerves and extraocular muscles in patients with neuropathic strabismus.

INTRODUCTION: Although the ocular motility examination has been used traditionally in the diagnosis of strabismus that is a result of cranial nerve (CN) abnormalities, magnetic resonance imaging (MRI) now permits the direct imaging of lesions in CN palsies. METHODS: Prospectively, nerves to extraocular muscles (EOMs) were imaged with T1 weighting in orbits of 83 orthotropic volunteers and 96 strabismic patients in quasicoronal planes using surface coils. Intraorbital resolution was 234-312 microns within 1.5- to 2.0-mm thick planes. CNs were imaged at the brainstem using head coils and T2 weighting, yielding 195 micron resolution in planes 1.0-mm thick in 6 normal volunteers and 22 patients who had oculomotor (CN3), trochlear (CN4), or abducens (CN6) palsies and Duane syndrome. RESULTS: Oculomotor (CN3) and abducens (CN6) but not trochlear (CN4) nerves were demonstrable in the orbit and skull base in all normal subjects. Patients with congenital CN3 palsies had hypoplastic CN3s both in orbit and skull base, with hypoplasia of involved EOMs. Patients with chronic CN6 and CN4 palsies exhibited atrophy of involved EOMs. Patients with Duane syndrome exhibited absence or hypoplasia of CN6 in both orbit and brainstem regions, often with mild hypoplasia and apparent misdirection of CN3 to the lateral rectus muscle. Unlike CN6 palsy, patients with Duane syndrome exhibited no EOM hypoplasia. Patients with congenital fibrosis exhibited severe hypoplasia of CN3, moderate hypoplasia of CN6, and EOM hypoplasia, particularly severe for the superior rectus and levator muscles. CONCLUSION: High-resolution MRI can directly demonstrate pathology of CN3 and CN6 and affected EOM atrophy in strabismus caused by CN palsies. Direct imaging of CNs and EOMs by MRI is feasible and useful in differential diagnosis of complex strabismus.     

Malnutrition as a prognostic factor in lymphoblastic leukaemia: a multivariate analysis

One hundred and twenty eight Brazilian children with lymphoblastic leukaemia were intensively treated with a Berlin-Frankfurt-Munich based protocol. More children had a white cell count above 50 x 10(9)/l (31%) then observed in developed countries. After a median follow up of 31 months (11-58 months), the estimated probability of relapse free survival was 41% (7%) for the whole group. After adjustment in the Cox's multivariate model, malnutrition was the most significant adverse factor affecting duration of complete remission. Age above 8 years and high peripheral white cell count were also significant adverse factors. Among the nutritional indices, the height for age and weight for age z scores were both significant, whether the cut off points of z-2 or z = -1.28 were chosen to define malnutrition. A strong statistical association between the two indices was found; the contribution of height for age z score to the prediction of relapse free survival was more significant. Children with height for age z score < -2 had a relapse risk of 8.2 (95% confidence interval 3.1 to 21.9) relative to children with z score > -2. The results of this study suggest that socioeconomic and nutritional factors should be considered in the prognostic evaluation of children with leukaemia in developing countries.     

The anterior junction line: a radiographic sign of bilateral pneumothorax in neonates

The anterior junction line is a normal anatomic landmark on chest radiographs of healthy adults and older children caused by the visceral and parietal pleurae of the two lungs meeting anteriorly at the midline. It is not seen on chest radiographs of healthy infants. When this sign is identified on the supine frontal view of a neonate, it signifies bilateral pneumothorax. In this situation the line is formed by the meeting of the medial parietal pleurae on each side as they herniate anteriorly in front of the thymus and heart. The sign is best seen when the patient is rotated slightly to the left. It is not seen when there is unilateral pneumothorax or a concomitant pneumomediastinum. Although the anterior junction line is not a highly sensitive indicator of bilateral pneumothorax, it is highly specific and its recognition can promote faster diagnosis.     

Mutations induced by DNA double-strand breaks: The influence of genomic site

The transgenic CHO cell line PL61, carrying a recombinant SV40-gpt gene, was treated with restriction endonucleases to assess mutagenesis from defined DNA double-strand breaks. Mutations ingpt were measured under two conditions: a stringent condition where selection ensured that the closely-linkedneo gene was retained functionally intact, or a relaxed condition without the requirement forneo gene function. Despite testing 18 different restriction endonucleases with various numbers of potential break-sites within the transgene, mutations were only found under relaxed selection conditions. These mutations commonly led to complete loss of the transgene, suggesting that large deletions predominate when selection is relaxed. It is argued, in comparison to mutation data for other genomic sites in CHO cells, that variations in the ‘effective target size’ for mutagenesis may explain the response of the transgene under different conditions.     

Mechanical performance of sutures in surgery.

In this study, we have compared the recommended configuration of a knot with specified sutures as ascertained by mechanical performance tests to that employed by a group of board-certified surgeons. Agreement between the surgeon and the results of the test was encountered in only one fourth of the instances. In another one fourth of the cases the surgeon overestimated the number of throws required for a knot to reach knot break. This additional suture material further handicaps the host's defenses, thereby inviting infection. Surgeons employed knots that untied without reaching knot break in the remaining half of the cases. The holding power of many of the knots that untied was substantially less than that of knots reaching knot break. On the basis of the study, it is recommended that results of the mechanical performance tests be made readily available to the surgeon so that his patient can receive maximal benefits from the knotted suture with the least damage to the host's defenses.     

Health care decision making in southern county

We combine two standard approaches to analyze power and influence in health policy formulation within a moderately large county in the south. Intrinsic methodologic weaknesses are discussed and several conclusions are drawn regarding power in the health care sector of that community. The most significant finding is the shift in power over time, away from the individuals to committees and health care organizations. The ignorance of most physicians about the broader health care issues that affect the community was reflected in their lack of recognition by others in the community as influential decision makers. The insular relationship of the university to the rest of the community was also noted. Past racial politics had a continuing effect on later health policy formulation. These findings are discussed in light of current and past issues. Because we had promised confidentiality to the persons we interviewed, fictitious names were given to the county, the institutions, and the interviewees.     

The effects of eticlopride on Morris water task performance in male and female rats neonatally treated with quinpirole

Rationale Previous studies have shown that neonatal quinpirole treatment which results in long-term dopamine D2 receptor supersensitization (D2 receptor priming) produces cognitive deficits in preweanling and adult rats behaviorally tested on the Morris water task (MWT).Objective This study was designed to analyze whether pretraining administration of the D2 antagonist eticlopride alleviates cognitive deficits produced by neonatal quinpirole treatment.Methods Both male and female Sprague–Dawley rats were treated with quinpirole HCl (1 mg/kg) or saline from postnatal days 1 to 21. From P22 to P24, rats were tested on the place version of the MWT in which a hidden platform remains stationary throughout training. From P25 to P28, rats were tested on the match-to-place version of the MWT, and rats are given a pair of daily training trials to locate the hidden platform that was moved to a new location each day. Fifteen minutes before each training session, rats were intraperitoneally administered with eticlopride (0.01 or 0.02 mg/kg) or saline.Results Pretraining eticlopride treatment alleviated cognitive deficits produced by neonatal quinpirole treatment in both male and female rats on the place version of the MWT, as well as in males tested on the match-to-place version of the MWT. However, there were no significant deficits produced by neonatal quinpirole treatment in females tested on the match-to-place version of the MWT, and control males demonstrated superiority over control females on this version of the task.Conclusions Pretraining administration of the dopamine D2 antagonist eticlopride alleviated cognitive deficits produced by neonatal quinpirole treatment. However, it appears that the dopamine D2 receptor may have a more important influence on cognitive performance in males than in females, which may be related to increased sensitivity of the D2 receptor in males.