Aggregation fo blood platelets and increased hydraulic conductivity of pulmonary exchange vessels

Pulmonary microembolization secondary to platelet aggregation has been suggested to be a pathogenetic component of the shock lung syndrome. In vitro experiments have also shown that platelets can release factors with a permeability-enhancing activity. We studied the effect of collagen-induced platelet aggregation on the hydraulic conductivity of thexchange vessels in isolated, blood-perfused rabbit lungs. The net rate of fluid filtration in each pair of lungs was determined during standardized elevations of left atrial pressure before and after platelet aggregation induced by intraarterial collagen infusions. Such infusions were followed by a significant, but transient increase in the net rate of fluid filtration. These lungs were papaverinized so that collagen infusions caused only minor increases in inflow pressure. Separate experiments indicated that the observed increase in pulmonary arterial pressure could not explain the increase in net filtration rate after collagen infusion. When platelet-poor plasma was used as a perfusate no change in the net rate of fluid filtration was observed after collagen infusion. The conclusion from these experiments is then that intravascular platelet aggregation induced by collagen infusion caused a transient increase in the permeability of the pulmonary exchange vessels.     

Hodgkin's disease in children: clinico-roentgenologic features of the lesion in the chest

The roentgenologic features of Hodgkin's disease were studied in 105 patients under 14 years of age. The mediastinal and hilar nodes were involved in 64.7% of patients. Some consistency of extent and pattern of disease was observed in that mediastinal lymphatic lesions could be associated with cervico-supra-clavicular and retroperitoneal lesions. There was lung infiltration in 14.3% of patients and the frequency of this lesion dependent on the histological type. It was commoner in nodular sclerosis, mixed cellularity and lymphocytic depletion. Lung infiltration usually developed in continuity with the lymphatic gland lesion and only rarely in a metastasis-like form.     

Frontal cortex and response suppression in the rat

Parts of the rat's neocortex were mapped for sites where electrical stimulation, square waves at 10/sec, will suppress a bar-press response for food. Effective sites were found in the frontal pole and over most of the frontal dorsolateral cortex. Within these regions the strongest inhibitory influences were at sites in the frontal pole and adjacent frontal cortex, and at sites along the midline. These data generally agree with results of previous cortical ablation studies, but they suggest that inhibitory processes are more widespread in the dorsolateral cortex than these studies indicated.