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.     

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.     

Freezing temperature of finger skin

In 45 subjects, 154 frostnips of the finger were induced by cooling in air at -15 degrees C with various wind speeds. The mean supercooled skin temperature at which frostnip appeared was -9.4 degrees C. The mean skin temperature rise due to heat of fusion at ice crystallization was 5.3 degrees C. The skin temperature rose to what was termed the apparent freezing point. The relation of this point to the supercooled skin temperature was analyzed for the three wind speeds used. An apparent freezing point for a condition of no supercooling was calculated, estimating the highest temperature at which skin freezes at a given wind speed. The validity of the obtained differences in apparent freezing point was tested by an analysis of covariance. Although not statistically significant, the data suggest that the apparent freezing point with no supercooling decreases with increasing wind velocity. The highest calculated apparent freezing point at -15 degrees C and 6.8 m/s was 1.2 degrees C lower than the true freezing point for skin previously determined in brine, which is a statistically significant difference.     

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.     

The cyclopentolate provocative test in suspected or untreated open-angle glaucoma. V. Statistical analysis of 431 eyes

The mydriasis provocative test with 1% cyclopentolate (CPT) was performed on 431 eyes with suspected or untreated open-angle glaucoma. Tonography was performed both before and during CPT to study the changes in aqueous dynamics during the test. Statistical analysis of the results yielded the following mean trends and correlations at a highly significant level (P less than 0.001) in the alterations: Intraocular pressure (IOP) rose (deltaP +/- SD) (+ 1.4 +/- 2.9 mmHg) and aqueous outflow facility decreased (deltaC) (-10%) during CPT. The distribution of deltaP and deltaC did not follow the normal Gaussian distribution. The change in deltaP deviated from the Gaussian distribution in 5-10% of the eyes. The deviating values concur with those of the responder eyes in which IOP rose greater than or equal to 8 mmHg during CPT. deltaP was linearly dependent on the initial IOP level Po and the absolute change was always almost constant, approximately +1.4 mmHg. Both the total series and the responder eyes displayed the same trend for the change in aqueous outflow facility in relation to the initial C value (Co): low Co values changed less on average and high Co values changed more and diminished. It is not known why the deltaC change was different depending on the Co value. The change in IOP correlated statistically highly significantly in the initial C value (Co). The loqwe the Co value, the higher was the mean IOP elevation during CPT. In contrast, the change in aqueous outflow (deltaC) did not corrrelate (N.S.) with the initial IOP level (Po) before CPT.     

Hatching of Schistosoma mansoni eggs and observations on motility of miracidia

Eggs of Schistosoma mansoni were obtained from livers of mice and hatching was observed under varying conditions of light and ionic composition of the medium. Hatching occurred equally well in light and in darkness. Eggs also hatched readily in 1- to 50-m OsM solutions of urea, sucrose, sodium chloride, and glycerol, but hatching was inhibited at higher concentrations unless the eggs were left in solutions for long periods of time. Hatching readily occurred in deionized water, but the emerged miracidia did not swim longer than 5 to 10 min unless Na+ was added. Histochemistry of the egg showed DNA-positive egg granules and a polysaccharide-positive vacuole matrix. Acid mucopolysaccharides were stained in the vacuolar matrix and in the anterior sac of the miracidium. Longitudinal alignment of constituents of the egg shell is suggested by the predominance of longitudinal rents in the shell at hatching. A mechanism of hatching involving an osmotic stimulus is proposed.