Myopathy with Central Cores in a Foal

Central core disease is a nonprogressive or slowly progressive congenital myopathy with a variable degree of hypotonia and axial and proximal muscle weakness that is histologically characterized by areas devoid of oxidative enzyme activity, resulting from an absence or low numbers of mitochondria in these regions (central core). A 10-month-old, male, pony foal was examined because of stiff gait, marked contractures of the distal portion of the limbs, flexion deformities of the hooves, and moderate hypotonia that had been present from birth. The foal had increased creatine kinase (282 U/ liter; reference interval 10-135 U/liter), lactate dehydrogenase (1,188 U/liter; reference interval 150–450 U/liter), and aspartate transaminase (377 U/liter; reference interval <290 U/liter) activities, suggesting muscle disease. Muscle biopsy was performed. In cytochrome oxidase-, succinate dehydrogenase-, and reduced nicotinamide adenine dinucleotide tetrazolium reductase-reacted sections, the dominant morphologic feature was the absence of oxidative enzyme activity in the cores. By use of immunohistochemical technique with a monoclonal antibody against desmin, the cores were clearly delineated and a desmin network was present within the cores. Ultrastructurally, the core areas were characterized by preserved sarcomeres with irregular Z-lines, with some streaming or zigzag appearance and abnormal sarcoplasmic reticulum profiles and T-tubules. Lack of mitochrondria within central cores was observed. Diagnosis of myopathy with central cores was made.

A multicancer-like syndrome in a dog characterized by p53 and cell cycle-checkpoint kinase 2 (CHK2) mutations and sirtuin gene (SIRT1) down-regulation

INTRODUCTION

We have investigated SIRT1, p53 and cell cycle-checkpoint kinase 2 (CHK2) gene dysfunction in a dog with a multicancer syndrome-like in order to evaluate their potential role in the determinism of the disease and to establish a possible correlation between SIRT1 transcript level and p53 expression status.

MATERIAL AND METHODS

Blood sample and tumour samples from a pure breed English Setter dog with different tumours were used for this study. Nucleotide sequence analysis was performed with a DNA autosequencer in order to examine p53 and CHK2 mutations. In addition, the expression level of SIRT1 was quantified by Southern Blot analysis of Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR).

RESULTS

Cytological examination revealed five different tumours: a cutaneous sebaceous epithelioma, a cutaneous mast cell tumour, a testicular Sertoli cell tumour, an oral malignant melanoma, and a cutaneous squamous cell carcinoma. Sequencing analysis revealed the presence of a nucleotide substitution, (CGG>CAG) exon 7 of the p53 gene in DNA from peripheral blood mononuclear cells (PBMCs) as well as in the melanoma; whereas the other four cancers showed the loss of the wild-type allele. Furthermore, CHK2 mutation at codon 311 has been identified in the melanoma and sebaceous epithelioma. In addition, SIRT1 cDNA expression decreased in all tumour samples compared to cDNA SIRT1expression level in peripheral blood mononuclear cells (PBMCs) in the same dog.

CONCLUSIONS

These results suggest that the germ line mutation of the p53 gene at codon 248 might be, at least, one cause of the multicancer syndrome-like in our dog; furthermore, we show a possible correlation between SIRT1 transcript level and p53 mutations status. The regulatory role of SIRT1 in tumour suppressor pathways suggests that the net effect seen may represent both direct and indirect downstream regulation and it is likely to depend on the presence or absence of functional p53.

Effectiveness of intrapartum penicillin prophylaxis in preventing early-onset group B streptococcal infection: results of a meta-analysis

OBJECTIVE

To determine the effectiveness of intrapartum penicillin prophylaxis in preventing early-onset group B streptococcal (GBS) infection in neonates of women whose birth canals are colonized by group B streptococci.

DATA SOURCES

Articles published between 1966 and 1992 identified from MEDLINE, EMBASE, the Science Citation Index and the Oxford Perinatal Database; the bibliographies of primary studies, textbooks and review articles and published abstracts from major conferences and symposia.

DATA SELECTION

Studies were selected if four criteria were met: (a) the target population was intrapartum women and neonates, (b) the intervention was penicillin prophylaxis, (c) invasive early-onset GBS infection was an outcome measure, and (d) the studies were controlled trials or cohort studies. Seven primary studies were identified, four of which were randomized controlled trials.

DATA EXTRACTION

Explicit methodologic criteria were used by two of the authors to assess independently the study quality; one of the reviewers was blind as to author, institution and journal. The baseline characteristics of the population, intervention and outcome were summarized twice and checked for accuracy by two of the authors.

DATA SYNTHESIS

Five of the studies showed a trend toward a beneficial effect of penicillin prophylaxis, and two showed a statistically significant effect. The pooled odds ratio indicated a 30-fold reduction (95% confidence interval 0.0013 to 0.17) in the incidence of early-onset GBS infection with intrapartum penicillin prophylaxis. Subgroup analyses did not change these results. The magnitude of improvement observed did not differ between women with prenatal risk factors (premature rupture of the membranes and premature labour) and those without these risk factors.

CONCLUSIONS

There is accumulative evidence that intrapartum penicillin prophylaxis is effective in preventing early-onset GBS infection. Such therapy is beneficial to women whose birth canals are colonized with group B streptococci. Further studies are needed to determine the optimum timing and method of detecting vaginal colonization during pregnancy.

Improved outcome of respiratory syncytial virus infection in a high-risk hospitalized population of Canadian children. Pediatric Investigators Collaborative Network on Infections in Canada

PURPOSE

To determine the outcomes in children at high risk for death or complications from respiratory disease who are hospitalized with respiratory syncytial virus (RSV) infection.

DESIGN

Retrospective chart review.

SETTING

Twelve pediatric tertiary care centers.

PATIENTS

All hospitalized children with an RSV infection diagnosed by a positive antigen detection test result or viral isolation during the study period from 1988 to 1991, encompassing three winter seasons. Charts from patients in the following high-risk groups were reviewed in detail: (1) congenital heart disease, (2) chronic lung disease, (3) immunodeficiency, (4) age less than 6 weeks, (5) gestational age less than 36 weeks, and (6) hypoxia (defined as oxygen saturation less than 90% or arterial oxygen pressure less than 60 mm Hg).

MEASUREMENTS

The age of all children, the date of RSV identification, and the use of oxygen supplementation, intensive care, and ventilatory support. In addition, the duration of these treatments and the duration of hospitalization were noted. Left-to-right shunting and pulmonary hypertension before RSV infection were determined in those children with congenital heart disease. The nature of the chronic lung disease was noted. Death within 2 weeks of RSV identification was recorded, and the use of ribavirin, bronchodilators, and corticosteroids was determined.

RESULTS

Significant year-to-year variation in the frequency of RSV infection was confirmed, with a peak during the 1989-1990 winter noted by the majority of centers (p = 0.0001). Of the 1584 patients in the study, 260 had underlying cardiac disease, 200 had chronic lung disease, 35 had compromised immune function, 378 had been premature, 373 were less than 6 weeks of age, and 338 had hypoxia. Seventeen patients died within 2 weeks (mortality rate 1%); significantly more patients with underlying cardiac disease (3.4%) or lung disease (3.5%) died. Immunocompromised patients had the longest hospital stay (median 39 days), followed by those patients with underlying cardiac or pulmonary disease (11 days); patients less than 6 weeks of age (5 days) and those with hypoxia (6 days) had the shortest hospital stays. Patients with underlying cardiac and pulmonary disease also required oxygen supplementation for a significantly longer period.

CONCLUSION

The year-to-year variation in frequency of RSV infection was confirmed in this study. Morbidity and mortality rates associated with RSV infection in a high-risk population in Canada were significantly lower than previously reported.

Initial therapy of bacterial meningitis with cefuroxime: Experience in 167 children

The morbidity and mortality of patients with bacterial meningitis treated initially with cefuroxime were studied and compared with the results of a previous prospective study of patients treated initially with ampicillin plus chloramphenicol in the same institution from 1979 to 1983. A retrospective chart review was completed in all cases of microbiologically confirmed bacterial meningitis admitted to the Hospital for Sick Children in Toronto, Ontario between January 1, 1984 and August 1, 1988. During this period all patients were treated initially with intravenous cefuroxime. The 167 children reviewed ranged in age from six weeks to 17.1 years (median 11.6 months). The case fatality rate was 7.8% and the rate of hearing deficit 13%. There were no statistically significant differences in abnormal neurological outcome (20 versus 20%, respectively), hearing loss (12.9 versus 13%, respectively), and case fatality rate (6.4 versus 7.8%, respectively) between the cohort of 1979-83 and the present study. The rate of hearing loss following meningitis caused by Haemophilus influenzae type b increased from 7.3 to 11.7% (P=0.26).

Observer agreement for respiratory signs and oximetry in infants hospitalized with lower respiratory infections

To determine observer agreement for a clinical score and oximetry in lower respiratory infection in children less than 2 yr of age, a convenience sample of 56 infants hospitalized with bronchiolitis or pneumonia was assessed independently by two observers. A total of 12 infants had chronic lung disease of prematurity or congenital heart disease. Infants in whom oxygen supplementation could not be discontinued for at least 5 min were excluded. A severity score was assigned for each of four categories (respiratory rate, retractions, wheeze, and general appearance). A total for each patient was obtained by summing the score for each category. Oxygen saturation was measured using a Nellcor oximeter. Agreement beyond chance was measured using the kappa statistic. The relationship between observers for total score and oximetry and the mean total score and mean oximetry value for each patient was expressed as a Pearson correlation coefficient. A total of 56 infants and children were studied: 2 had pneumonia, 11 had an exacerbation of pulmonary signs and symptoms with their underlying cardiac or pulmonary disease, and 43 had bronchiolitis. Kappa was 0.48 for general assessment, 0.38 for respiratory rate, 0.31 for wheeze, and 0.25 for retractions. All values were statistically significantly greater than 0 at p less than 0.01. Correlations for total score and for oximetry were 0.68 and 0.88, respectively. The median difference between oximetry readings was 1. The correlation coefficient between total score and oximetry was -0.04. The limited agreement for clinical signs makes comparison of patient illness severity between studies difficult.(ABSTRACT TRUNCATED AT 250 WORDS)