Sternal metastases and associated pathological fractures

A review of 839 necropsies revealed 415 cases of malignant neoplasm, 63 of which were found to have evidence of metastatic spread to the sternum. Nineteen of these metastases resulted in pathological sternal fractures. Fine detail radiography proved a quick and accurate technique for detecting these lesions post mortem. The characteristics of pathological sternal fractures were compared with traumatic sternal fractures with respect to deformity and healing. Pathological fractures of the sternum demonstrate a tendency to greater deformity and slower healing than traumatic sternal fractures.     

Testosterone affects food intake and body weight of weanling male rats

The effects of testosterone propionate (TP) on food intake and body weight were investigated using castrated prepubertal male rats. Regardless of dose (1 mg, 0.2 mg or 0.1 mg), daily injections of TP increased body weight gain and food intake during the prepubertal period (from 22 to 40 days to age). Considering previous results, the present observations suggest that in the male rat sensitivity to the effects of gonadal hormones on feeding develops earlier than in females.     

Two T cell epitopes from the M5 protein of viable Streptococcus pyogenes engage different pathways of bacterial antigen processing in mouse macrophages

We studied the mechanisms of MHC class II-restricted bacterial Ag processing of the surface fibrillar M5 protein from viable Streptococcus pyogenes in murine macrophages. Two previously defined T cell epitopes were studied using T cell hybridomas specific for 308-319/Ad, associated with the cell wall on the surface of streptococci, and 17-31/Ed, located at the protruding amino terminus of M5. Studies with metabolic inhibitors showed that slow (1 h) processing of M5 308-319 occurred in late endosomes and was dependent on newly synthesized MHC class II molecules and microtubules and on communications between early and late endosomes, consistent with engagement of the classical MHC class II processing pathway. In contrast, fast (15 min) bacterial Ag processing of 17-31 occurred in early endosomes independently of newly synthesized MHC class II molecules and microtubules and of trafficking between early and late endosomes, consistent with the recycling MHC class II processing pathway. Finally, bacterial Ag processing of the epitopes exhibited differential sensitivity to blocking with anti-MHC class II Abs. Thus, two T cell epitopes of a single protective Ag from the surface of whole bacteria are routed to distinct MHC class II processing pathways.     

Influence of obstructive jaundice on jejunal absorption of glucose, electrolytes, and vitamin A in rats

Jejunal absorption of glucose, electrolytes, and vitamin A was investigated in rats. A Tyrode solution containing glucose, sodium, and potassium in concentrations two and four times higher than usual was infused through the jejunal loops of jaundiced and control rats during 40 min. The glucose values in the influx and effluent were not different during the experiment time. However, the concentrations of sodium and potassium of the effluent decreased with concentrations twice normal. The osmotic pressure of the effluent was directly related to the electrolytic concentration. When the perfusate fluid was four times higher, the differences between sham and jaundiced groups remained unchanged. The osmotic pressure means of the jaundiced group decreased during the experimental time. The absorption of vitamin A increased during the 40-min experiment time in the control rats. On the other hand, vitamin A concentration in the perfused lumen of the jaundiced group did not change over the time. These data indicate that obstructive jaundice has little influence on glucose and electrolytes absorption, while vitamin A is impaired by this condition.     

Central neural regulation of heart and blood vessels in mammals

The study of the central regulation of the circulation in the past has been directed primarily at observing reflex responses to stimulation of peripheral receptors and at producing changes in cardiovascular parameters during electrical stimulation of central sites. These studies have demonstrated that the nervous system can regulate the circulation to different vascular beds with a high degree of specificity and that it has the ability to provide a range of coordinated responses which are appropriate to the metabolic needs of a particular behavioural pattern. In addition, it has become firmly established that the nervous system is capable of coupling cardiovascular changes with other autonomic and somatic activities to produce an integrated response. In the last decade it has become apparent that although the mode of operation of central cardiovascular regulation has been described in general terms, very little is known about the accurate anatomical localization of neuronal circuits and pathways and of impulse traffic corresponding to the changes in cardiovascular parameters that have been observed. This essay reviews recent information on discrete neuronal circuits and pathways and their mode of operation in electrophysiological terms. One of the most serious difficulties in this endeavour is the problem of demonstrating specificity of pathways and circuits because patterns of firing of afferent and efferent peripheral nerves can be usually identified, but the demonstration of specificity of central structures is a conceptual and technical challenge to the most skilled investigator. Several studies have been made in the last decade in an attempt to trace anatomically and functionally pathways involved in central cardiovascular regulation. Progress has been made especially with regard to the precise sites of termination of cardiovascular afferent fibres and the pattern of discharge of efferent cardiovascular neurons; some work has also been done to trace discrete pathways between the hypothalamus and the medulla and the medulla and the spinal cord. However, in view of the difficulties of establishing the specificity of cardiovascular pathways, progress will depend on the acquisition of a wiring diagram of simple cardiovascular reflex arcs before attempts are made to study the functional interactions of regions in the brain that have been traditionally associated with central regulation of the circulation. Future experiments should concentrate less on the demonstration of cardiovascular responses to stimulation or lesions in the central nervous system and more on the connections of discrete regions.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effect of solvent structure on amide reaction with native DNA molecules. II. Aqueous acetamide mixtures

The influence of acetamide (AA) on the native DNA molecule conformation has been studied by methods of flow birefringence and viscometry. On one hand, it was shown that hydrodynamical and optical behaviour of the macromolecule at extremely low additions of AA is qualitatively the same as in the presence of nonelectrolytes which stabilize the water structure. On the other hand, the influence of intermediate and large AA concentrations on the native DNA molecule conformation is qualitatively the same as of corresponding urea concentrations, which is known to be a structure-breaker. The influence of AA on the thermostability of the native DNA molecule as well as on the stacking-association constant of adenosine has been studied by a spectrophotometric method. The obtained data confirm the hypothesis of the importance of ion-dipole interactions between nonelectrolytes and the phosphate groups of the DNA molecule.