An analysis of the need for pediatric surgeons in the United States

A questionnaire study covering all major population areas in the United States indicated that pediatric surgeons and potentially capable hospitals are already well-distributed throughout the country. The estimation of need for pediatric surgeons based on the area questionnaires is close to the present number of surgeons. A computer analysis was made to project numbers of pediatric surgeons per unit population to the year 2000 with differing levels of trainee output. The study indicates that 14-15 training programs are sufficient to allow for slow, modest growth of the specialty if current population trends continue.     

Interaction between radiation and drug damage in mammalian cells. II. The effect of actinomycin-D on the repair of the sublethal radiation damage in plateau phase cells

The effect of actinomycin-D (AMD) on radiation damage repair was studied in plateau phase V79 Chinese hamster cells. Sublethal radiation damage repair, as demonstrated by survival fluctuations following two x-ray exposures separted by time, was observed in our plateau phase cells. Plateau phase cells exposed to 0.01-0.04 mug/ml AMD (a nontoxic regimen to 8 hours) between x-ray exposures were less able to repair sublethal damage. If plateau phase cells were plated at low dilutions into fresh medium (conditions for resuming exponential growth) immediately after the first x-ray dose, and exposed to 0.01--0.04 mug/ml AMD until the second dose, inhibition of sublethal damage repair and additional cell killing were observed particularly at 0.04 mug/ml AMD. It is suggested that radiation-drug damage interactions should be studied in plateau phase cells and in cells resuming exponential growth after plateau phase (possibly analogous to "recruitment"), as well as in exponential phase cultures.     

Ultrastructures of atypical acinar cell nodules in rat pancreas induced by 4-hydroxyaminoquinoline-1-oxide

A single intravenous injection of 4-hydroxyaminoquinoline-1-oxide (4HAQO) to rats induces multiple atypical acinar cell nodules in the pancreas. In this study, the ultrastructure of cells in these nodules was examined at 6, 9, and 12 months, and the features were compared to those of developing embryonal pancreas. The cells in the nodules are exocrine acinar cells in type and exhibited several features which distinguish them from the nonnodular acinar cells. Irregular nuclear shape with enlarged nucleoli was frequently observed. Zymogen granules in the nodular cells appeared as vesicles with contents of extreme electrom lucency and their ultrastructural appearance was similar to those of developing embryonic pancreatic acinar cells at 16 and 18 days of gestation. At the cell periphery, the lateral cell membrane showed bizarre interdigitation and the ectoplasm showed hyaloplasmic rarefaction. These findings indicate that the acinar cell nodules induced by 4-hydroxyaminoquinoline-1-oxide are composed of a new population of phenotypically altered acinar cells showing nuclear abnormalities, modified cell to cell interaction, and a possible defect in synthesis and/or maturation of secretory enzymes. The latter may indicate an arrest in the differentiation of acinar cells. The significance of these findings is discusses, and it is suggested that the atypical nodules in the pancreas induced by 4-hydroxyaminoquinoline-1-oxide may represent early neoplastic foci.     

Glucose and bicarbonate reabsorption in edematous dogs

Glucose and bicarbonate reabsorption were studied in dogs made edematour by aortocaval fistula (A-V dogs) and in sham-operated dogs. Following construction of the A-V fistula, there was a significant increase in body weight; glomerular filtration rate, renal plasma flow, hematocrit, and sodium excretion decreased significantly. Bicarbonate reabosorption was significantly higher in A-V than in sham dogs both during control and volume expansion. Volume expansion depressed bicarbonate reabsorption significantly in both groups. Glucose reabsorption fell following volume expansion in both groups; glucose reabsorption was significantly higher in A-V dogs than in sham dogs during control and volume expansion. Volume expansion led to a minimal increase in sodium excretion in A-V dogs when compared to the increase in the sham dogs. These data demonsttate that chronic sodium retention is associated with enhanced reabsorption of glucose and bicarbonate. The site in the neophron responsible for the increase in reabsorption of these substances cannot be determined with certainty based on these clearance studies although it is possible that proximal reabsorption may be enhanced in this model.     

Circadian rhythms and photoperiodic time measurement in mammals

Many mammalian species display seasonal breeding patterns correlated with annual cycles of change in the physiology and morphology of the reproductive system. Such annual reproductive cycles are often photoperiodically controlled (i.e, the annual change in day length determines when reproductive activity begins and when it ends within the annual cycle). Photoperiodic control of seasonally appropriate changes in reproductive activity is dependent on an endogenous time measuring process. Among mammals the physiological basis of photoperiodic time measurement has been studied most extensively in the golden hamster. Studies with this species indicate that photoperiodic time measurement is executed by the circadian system. The time measuring process depends on a circadian oscillation of responsiveness to light with properties similar to those of the hypothetical rhythm originally proposed by Bünning to explain photoperiodic phenomena in plants. The available evidence strongly suggests the participation of the pineal gland and the suprachiasmatic nucleus (SCN) in the photoperiodic regulation of mammalian reproductive cycles. However, little is known regarding concrete physiological mechanisms, and the extent to which the SCN and the pineal gland may participate in the time measuring process per se remains to be determined.     

Study of TRH in the postganglionic sypnasis of the isolated human vas deferens

Cummulative dose-response curves to l-noradrenaline and in presence of different concentrations of TRH (10(-3), 10(-4), 10(-5), 10(-6), 10(-7), and 10(-8) M) were investigated. 25 segments of vas deferens (escrotal tract) were obtained from different surgical patients of urological disorders. At the lower concentration (greater than 10(-7) M), we can not appreciate any influence of TRH on the l-noradrenaline response. Nevertheless there was a reduction of response to l-noradrenaline, with displacement of the curves to the right side, for the high concentrations, and a proportional ratio to the concentration to TRH.     

Action of prolactin on ornithine decarboxylase activity in mammary gland explants of mice

Prolactin stimulated ornithine decarboxylase activity in mammary gland explants from midpregnant mice. The enhanced enzyme activity occurred in explants which were preincubated for 1 day in medium containing insulin, hydrocortisone, insulin plus hydrocortisone, or in medium containing no hormones. The largest prolactin effect was observed in tissues which were pretreated with insulin plus hydrocortisone; a greater than ten-fold increase in ornithine decarboxylase activity was observed when these tissues were incubated with prolactin for 2 hours. An effect of prolactin on ornithine decarboxylase activity was also observed in explants prepared from lactating mouse mammary glands.     

Althesin infusion for cardiac catheterisation

A trial of a continuous intravenous infusion of Althesin is described for sedation during cardiac catheterisation, both for children and adults. The conditions produced for the procedure were very satisfactory. The advantages and problems of its use are discussed. The technique justifies further trials.     

Family planning opinion leadership in Korea, 1971

The characteristics of Korean family planning opinion leaders are assessed through a secondary analysis of the 1971 national survey conducted by the Korean Institute for Research in the Behavioral Sciences. In effect, what characterized Korean family planning opinion leaders was a rather national and democratic model. Those who had tried methods, discussed them, and knew a lot about them assumed leadership roles more than others. Place of residence, education, and other such variables mattered relatively little unless a woman had credibility imparted by actual use and knowledge imparted by use or discussions with family planning professionals.