Development of functional connections between thalamic fibres and the visual cortex of the wallaby revealed by current source density analysis in vivo

Functional development of thalamic input to the cortex in anaesthetised wallaby pouch young between postnatal day 25 (P25) and P153 has been studied by electrical stimulation of the optic nerve, current source density (CSD) analysis, and histologic identification of recording sites. Conduction in the optic nerve was recorded prior to P39, by which time responses from the superior colliculus appeared. No evoked potential of cortical origin was recorded until P46, even though thalamic fibres grew into the cortical plate from P15. The first cortical synaptic responses were recorded at the margin of the subplate and the developing cortical plate, where cells that later comprise the adult layer 6 settle. At about P66, an additional short-latency, superficial response appeared, coinciding with the formation of layer 4. The deep response was retained in layer 6. Evoked activity in the presumed layer 4 was found progressively deeper in the cortex over the next few weeks, which would be expected from the addition of layer 3 above it. By P113, a new sink was added superficial in the cortex. Thalamocortical connections follow the same deep-to-superficial order in development as the cellular layers of the cortex.     

Temporal changes in key maternal and fetal factors affecting birth outcomes: A 32-year population-based study in an industrial city

Background

In Australia and internationally, there is concern about the growing proportion of women giving birth by caesarean section. There is evidence of increased risk of placenta accreta and percreta in subsequent pregnancies as well as decreased fertility; and significant resource implications. Randomised controlled trials (RCTs) of continuity of midwifery care have reported reduced caesareans and other interventions in labour, as well as increased maternal satisfaction, with no statistically significant differences in perinatal morbidity or mortality. RCTs conducted in the UK and in Australia have largely measured the effect of teams of care providers (commonly 6–12 midwives) with very few testing caseload (one-to-one) midwifery care. This study aims to determine whether caseload (one-to-one) midwifery care for women at low risk of medical complications decreases the proportion of women delivering by caesarean section compared with women receiving 'standard' care. This paper presents the trial protocol in detail.

Methods/design

A two-arm RCT design will be used. Women who are identified at low medical risk will be recruited from the antenatal booking clinics of a tertiary women's hospital in Melbourne, Australia. Baseline data will be collected, then women randomised to caseload midwifery or standard low risk care. Women allocated to the caseload intervention will receive antenatal, intrapartum and postpartum care from a designated primary midwife with one or two antenatal visits conducted by a 'back-up' midwife. The midwives will collaborate with obstetricians and other health professionals as necessary. If the woman has an extended labour, or if the primary midwife is unavailable, care will be provided by the back-up midwife. For women allocated to standard care, options include midwifery-led care with varying levels of continuity, junior obstetric care and community based general medical practitioner care. Data will be collected at recruitment (self administered survey) and at 2 and 6 months postpartum by postal survey. Medical/obstetric outcomes will be abstracted from the medical record. The sample size of 2008 was calculated to identify a decrease in caesarean birth from 19 to 14% and detect a range of other significant clinical differences. Comprehensive process and economic evaluations will be conducted.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN012607000073404.     

The anatomic cause of electrocardiographic changes in virus myocarditis of rabbits

Electrocardiographic studies were made on 25 rabbits which had been inoculated intratesticularly with virus III. During the acute stage of the resulting disease, the majority of these animals developed a histologically demonstrable myocarditis, and, after recovery from the infection, small scars were found in the myocardiums of many. Definite abnormalities in cardiac function, including complete auriculoventricular heart block, were demonstrated in the electrocardiogram during the period in which the acute myocarditis existed. The electrocardiogram failed to show the presence of a noteworthy myocarditis in only 3 animals, and in only one instance was it impossible to demonstrate myocarditis when the tracing was significantly altered. The electrocardiographic diagnosis was thus accurate in 84 per cent of the cases. This association of the abnormal electrocardiogram with the structural lesion in the heart leads to the conclusion that, in this disease of the rabbit, disturbed function is caused by actual lesions, and not by the toxicity of the disease.Twenty-one rabbits which were inoculated intratesticularly with Andrewes' inflammatory strain of the Shope fibroma virus were studied similarly. Although in the hearts of a few of these animals interstitial myocardial fibrosis occurred, the muscle cells escaped for the most part, and in no animal was any abnormality in the electrocardiogram demonstrated.     

EXPERIMENTAL SYPHILIS OF ORIENTAL ORIGIN: CLINICAL REACTION IN THE RABBIT

Two oriental strains of T. pallidum of Chinese origin were compared with two well known occidental strains, the Nichols and the Zinsser-Hopkins, on the basis of the clinical reaction to infection in the rabbit. Four experiments were carried out, two each in Peiping and New York. Animals from American and Chinese sources were represented in each experiment. The results obtained showed that the reaction to both Chinese strains was generally comparable to that of the American strains. But with both Chinese strains, lesions of the eyes were more frequent, the time relations of certain phases of the reaction were shortened, and there was a higher incidence of complete recovery (latency) within the observation period. In view of the well known variability of the syphilitic reaction, however, it was not felt that these qualitative differences in clinical response could be ascribed to inherent or biologically fixed properties of the strains.     

THE HEMOCYTOLOGICAL CONSTITUTION OF ADULT MALE RABBITS FROM FIFTEEN STANDARD BREEDS

A study of the red blood cells, hemoglobin, blood platelets, and the total and individual white blood cells was made on 180 male rabbits of known age and representing fifteen standard breeds. An attempt was made to eliminate or bold constant such variables as age, sex, season, time of examination, technical errors, food, housing, and disease. The mean, variance of the mean, and standard deviation were calculated for each breed sample and for the group as a whole. An analysis of the variance showed that the variation between the breed samples was significantly greater than the variation within the breed samples for the red blood cells, hemoglobin, blood platelets, total white blood cells, basophiles, eosinophiles, and lymphocytes per cubic millimeter and in per cent and the neutrophiles in per cent. No significant variations were detected in the monocytes except when the breeds were divided into heavy and light breeds. No variation in the neutrophiles per cubic millimeter was detected; a large number of the breeds had exactly the same mean neutrophile level. Characteristic blood formulae were found for the various breed samples having an adequate numerical representation. It was concluded that the varying blood formulae could not be explained on any other, except an hereditary (genetic) basis.     

EFFECT OF A FILTERABLE VIRUS (VIRUS III) ON THE GROWTH AND MALIGNANCY OF A TRANSPLANTABLE NEOPLASM OF THE RABBIT

A study of a malignant disease in rabbits has been made with reference to the presence or absence of a filterable virus, Virus III, in the tumor. The results are analyzed from the standpoint of certain characteristic features of the tumor process in order to determine any differences in degrees of malignancy. It was found that a more severe disease developed in the series in which the virus-bearing tumor was used than in the series in which the tumor was free of the virus, although the differences were not very marked and were not entirely constant. The influence of Virus III as a factor affecting malignancy has been discussed from the standpoint of its possible effect upon (α) the tumor cells and (b) the host reaction. It has been suggested that the greater malignancy of the pathological process usually induced by the virus-bearing tumor is attributable to a change in the response of the host to the tumor, which change is of the nature of a decreased resistance associated with the reaction of the host to the virus infection.