Interobserver variability in neonatal cranial ultrasonography

The reliability of cranial ultrasound diagnosis in the premature neonate was examined using data from an ongoing multicentre study of the epidemiology and long-term consequences of neonatal brain haemorrhage. First week ultrasound films (obtained at 4 hours, 24 hours and 7 days) from 60 study subjects were randomly selected for independent review by two groups of experienced interpreters, and results were recorded separately for observations (i.e. presence or absence of an abnormal echodense area on a film) and interpretations (i.e. presence or absence of haemorrhage or ventricular dilatation) in each hemisphere. Because of deaths in the first week of life, the total number of films examined was 138. Concordance on the presence or absence of an abnormal echodensity was examined for each individual film for three areas of interest: the germinal matrix, the ventricles and the parenchyma. Concordance on the presence or absence of haemorrhage or ventricular dilatation was examined only for the seventh-day film, or the final film prior to death. Finally, concordance was analysed with the diagnostic interpretations grouped into categories thought to differ prognostically for long-term outcome. In general, concordance was poorest for germinal matrix lesions and best for parenchymal lesions. Concordance was lower for observations made on each individual film than it was for interpretation of the final film in each case. Fifty-five of 60 cases (92%) were assigned to the same major prognostic category by both readers. Ultrasound review conferences were held periodically and there was evidence that concordance in ultrasound reading and interpretation improved during the course of the study.     

Relationship between production of epidermal growth factor receptors, gene amplification, and chromosome 7 translocation in variant A431 cells

Synthesis of the epidermal growth factor (EGF) receptor has been analyzed in a series of variant A431 human epidermoid carcinoma cell clones reported to contain different amounts of EGF binding sites. The amount of EGF receptor protein, quantitated by immunoaffinity chromatography, and EGF receptor mRNA, quantitated by cDNA hybridization, were closely correlated to the extent of EGF receptor gene amplification. This correlation existed in variants selected for reduced EGF receptors and in revertants from those variants with increased EGF receptors. There was also a correlation between the frequency of translocation of chromosome 7, containing the EGF receptor gene, and EGF receptor protein. These results support gene amplification as the mechanism enhancing A431 cell EGF receptor protein and determining growth responses.     

Calcitonin gene-related peptide in cardiovascular tissues of the rat

The distribution of calcitonin gene-related peptide immunoreactivity in the cardiovascular system of the rat was investigated by radioimmunoassay and immunocytochemistry. The nature of the immunoreactivity was studied by gel permeation and high performance liquid chromatography. Immunocytochemistry demonstrated the existence of calcitonin gene-related peptide-containing nerve fibres throughout the cardiovascular system. These were present in all regions of the heart, particularly in association with the coronary arteries, within the papillary muscles and within the sinoatrial and atrioventricular nodes. Calcitonin gene-related peptide-containing fibres were found mainly in the adventitia of the arteries and veins. Calcitonin gene-related peptide concentrations were high in major arteries and veins but comparatively low in the heart, aortic arch and thoracic aorta. Chromatography showed that approximately 70% of the total immunoreactivity was identical to synthetic calcitonin gene-related peptide. Calcitonin gene-related peptide concentrations in the blood vessels of rats treated neonatally with capsaicin were not found to be significantly different from those in control animals although capsaicin caused significant reductions of calcitonin gene-related peptide levels in certain other tissues. The results of this study suggest that calcitonin gene-related peptide-containing fibres are likely to be of importance in the innervation of vascular tissues and raise the possibility that these fibres are different in character from calcitonin gene-related peptide-containing fibres found in other tissues.     

Effect of Chlamydia pneumoniae on cellular ATP content in mouse macrophages: role of Toll-like receptor 2

Chlamydiae are obligate intracellular gram-negative bacteria and are dependent on the host cell for ATP. Thus, chlamydial infection may alter the intracellular levels of ATP and affect all energy-dependent processes within the cell. We have shown that both live C. pneumoniae and inactivated C. pneumoniae induce markers of cell death prior to completion of the bacterial growth cycle. As depletion of ATP could account for the observed increase in cell death, the effects of C. pneumoniae on ATP concentrations within mouse macrophages were investigated. Live, heat-killed, and UV-inactivated C. pneumoniae cultures (at multiplicities of infection [MOIs] of 0.01, 0.1, and 1.0) were incubated with mouse bone marrow macrophages isolated from C57BL/6J mice and mice deficient in Toll-like receptors. Treatment of the macrophages with both live and inactivated C. pneumoniae increased the ATP content of the cells. In cells infected with live C. pneumoniae, the increase was inversely proportional to the MOI. In cells treated with inactivated C. pneumoniae, the increase in ATP content was smaller than that induced by infection with live organisms and was proportional to the MOI. The increase in ATP content early in the developmental cycle was independent of the growth of C. pneumoniae, while sustained induction required live organisms. The capacity of C. pneumoniae to increase the ATP content was ablated in macrophages deficient in expression of either Toll-like receptor 2 or the Toll-like receptor accessory protein MyD88. In contrast, no effect was observed in macrophages lacking expression of Toll-like receptor 4.     

Identification of a recombination event narrowing the Lafora disease gene region.

Patients affected with progressive myoclonus epilepsy of the Lafora type present during late adolescence with a characteristic EEG pattern and Lafora bodies seen on skin biopsy. The critical region for the Lafora gene has been localised to chromosome 6q24 flanked by the dinucleotide repeat markers D6S292 and D6S420. This study for linkage of markers from the candidate gene region was performed in a previously unpublished family affected with Lafora disease. EEG and skin biopsy evaluation for Lafora bodies were performed on five of eight family members followed for seizure activity. Haplotype and linkage analysis of DNA from five family members were carried out using the nine dinucleotide repeat markers reported in the common region of homozygosity by Serratosa et al in 1995. The present study of an additional family affected by Lafora disease has narrowed the 17 cM critical region for the Lafora disease gene on chromosome 6q24 to a 4 cM region flanked by markers D6S308 and D6S311.     

Effects of repeated maternal separations on the adrenocortical response to stress of preweanling rats.

Previous data indicate that the infant rat shows a marked increase in adrenocortical responsiveness to stress immediately following prolonged maternal separation. In Experiment 1 we studied the immediate effects of repeated maternal deprivation. Our results indicate that the increase in basal as well as stress-induced corticosterone levels is a direct function of the length of the deprivation period immediately preceding testing, and is not cumulative. In Experiment 2 we examined the long-term consequences of maternal deprivation on adrenal responsivity. Four days following a single 24-h period of maternal deprivation, pups remained hyperresponsive to stress, although their basal levels of corticosterone had returned to control values. Shorter periods of deprivation (which did result in increased responsivity immediately following deprivation) did not have persistent effects. Our data suggest: 1) short periods of deprivation do not have a cumulative effect, and 2) there is a critical length of deprivation beyond which persistent changes in adrenocortical responsivity ensue.