A study in vivo of peritubular oncotic pressure and proximal tubular reabsorption in the rat

1. Peritubular capillary microperfusion was used to examine the effects of protein-free and hyperoncotic homologous plasma on fluid reabsorption by proximal convoluted tubules in the hydropenic rat. 3H-labelled p-aminohippurate was added to perfusates for the purpose of estimating the extent to which tubules under study were bathed by the perfusates. [14C]Mannitol was added to perfusates in order to detect contamination of collected tubular fluid by perfusates. 2. Hydrostatic pressures were monitored in the peritubular microvasculature and adjacent proximal tubules during perfusion. Evidence for secretion of p-aminohippurate from perfusate into tubules under study was determined by collecting tubular fluid from both early and late puncture site. Fractional and absolute reabsorption were not affected by either the protein-free or the hyperoncotic plasma. 3. When acetazolamide was added to the perfusate both fractional and absolute reabsorptive rates decreased by an average of 36%, indicating that the techniques were capable of detecting a decrease in proximal tubular reabsorption. 4. It is concluded that under the conditions of this study changes in peritubular capillary protein concentrations have no detectable effect on the rate of proximal convoluted tubule fluid reabsorption.     

Minimum Cost Quality Control Tests

An expected cost model of a process whose mean is controlled by an X chart is developed. A two-stage numerical procedure is used to calculate the sample size, the number of units produced between samples, and the control limits of optimal control charts. Optimal plans are tabulated for three values of the a priori distribution parameter and three values of each of the three cost coefficients.     

Comparison of mortality of patients with heart attacks admitted to a coronary care unit and an ordinary medical ward

During a 32-month period 2047 patients suspected of having heart attacks were admitted to hospital and were followed up prospectively. Out of 1480 eventually found to have definite or probable myocardial infarction, 483 had initially been admitted to an ordinary medical ward because of the shortage of coronary care unit (CCU) beds. More patients aged over 65 had been admitted to a ward than to a CCU, and more patients aged 65 or less had been admitted initially to a CCU. Within each age group, however, patients admitted initially to a CCU were clinically similar to those admitted initially to a ward. There was a higher proportion of successful resuscitations among patients admitted to a CCU, but there was no significant difference in mortality in either age group between patients admitted to a CCU and a ward.     

Respiratory electromyographic estimates of ventilatory functions in piglets

The best electromyographic (EMG) predictors of respiratory drive (P100), tidal volume (VT) and ventilation (VE) were determined from diaphragmatic (DI) and posterior cricoarytenoid (PCA) EMG measures in 8-48-day-old, anesthetized piglets. Progressive hypercapnia was employed to obtain a wide range of muscle activity. A custom-designed, microcomputer-based system was employed to measure the duration, peak amplitude, rate of rise (initial slope) as well as the summed total and initial (first 100 ms) EMG activity from the DI and the PCA. For each respiratory function, the following combinations of EMG measures were identified as significant predictors using regression analyses: (1) for P100, DI amplitude, PCA initial area and PCA rate of rise; (2) for VT, DI amplitude, PCA duration and DI duration; (3) for VE, DI amplitude, DI initial area, PCA initial area, PCA rate of rise, PCA duration, DI area and DI rate of rise. Thus, whereas the traditionally employed measure of DI amplitude is an important correlate of P100, VT or VE, a complete estimate of these respiratory functions requires the inclusion of initial EMG measures and duration.     

The emerging field of the sociology of psychological knowledge.

Considers the social context in which professional academicians practice psychology. The ties of psychological knowledge to the infrastructure of society are noted, and comparisons with the sociology of knowledge are made. The underlying social biases of 5 areas within psychology (differential, humanistic, developmental, behavioristic, and social) are reviewed. Recent articles from the American Psychologist are sampled to indicate the growing awareness by the profession of the social base of its activities. (86 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Termination at midpregnancy of the two daily surges of plasma prolactin initiated by mating in the rat

The pattern of plasma prolactin following uterine cervical stimulation consists of two surges each day, one nocturnal, occurring between 0100-0900 h (lights on 0600-1800 h), and one diurnal, occurring between 1500-2100 h. This pattern of prolactin continued throughout pseudopregnancy; the last surge was observed on the morning of day 11 (day 1 was taken as the first day of diestrus of pregnancy or pseudopregnancy). Prolactin levels remained low thereafter until the spontaneous proestrous surge on the afternoon of day 12, signalling the onset of a new estrous cycle. In contrast, the two daily prolactin surges did not continue throughout pregnancy, and in fact, were terminated sooner in pregnant animals than in pseudopregnant animals. The last diurnal surge was observed on day 8 while the last nocturnal surge was observed on day 10. The early termination of prolactin surges during pregnancy correlated with the increased secretion of rat placental lactogen. However, placental extracts obtained from day 11 of pregnancy and injected in large doses failed to inhibit prolactin surges in pseudopregnant animals. Prolactin surges also continued for a longer period of time in pseudopregnant rats bearing decidualized uteri than in pregnant animals. Thus, the two major components of pregnancy that differed from pseudopregnancy, that is, the presence of rat placental lactogen or decidual tissue, did not appear to account for the early termination of prolactin surges during pregnancy.     

RNA metabolism of the normal and the copper treated human endometrium

Ribonucleic acid (RNA) metabolism of the normal and copper-treated ( Cu-T200 IUD) human endometrium was investigated. The relative concentration of total, messenger, ribosomal and transfer RNA was measured in normal and Cu-treated endometrium using the technique of affinity chromatography in polysepharose. The transition from the proli ferative to the secretory endometrium in normal women was accompanied by significant increases (p less than .05) in total RNA, messenger RNA and in ribosomal RNA. The relative proportions of bound and free messenger RNA were also modified by endometrial maturation changing from 70% bound messenger RNA in the proliferative to 83% in the secretory phase. Cu-T200 Cu release appeared to particularly affect RNA metabolism in the secretory phase. During the proliferative phase only the concentration of transfer RNA and the proportion of bound to free messenger RNA were modified by the Cu-T200. The Cu-T200 induced significant decreases (p less than .01 and p less than .05) in all RNA parameters, with the exception of the RNA/deoxyribonucleic acid ratio.     

Secretion of a bone resorbing factor by chick thyroid glands in organ culture

The ability of the thyroid gland to secrete a bone resorbing factor in vitro was studied using glands obtained from 20-day-old chick embryos. The glands were incubated in a modified BGJ medium containing 1 mg/ml bovine serum albumin under 5% CO2-40% O2 at 37 C. The culture media were assayed in vitro by measuring the stimulation of the release of previously incorporated 45Ca from cultured 19-day fetal rat bone shafts over a 48 h period. The glands secreted a stimulator of bone resorption which did not appear to be parathyroid hormone (PTH). The dose-response curve for the thyroid gland factor was not parallel to that obtained using PTH and secretion was not under calcium control. Neither thyroxine (T4) nor triiodothyronine (T3) produced a marked stimulation of bone resorption over a wide range of doses. Bone resorption stimulated by the thyroid gland factor was inhibited by calcitonin (CT). Concentrations of TH and thyroid gland factor which were minimally effective when tested separately, produced a marked synergistic response when added together. This synergism was not seen when T4, T3, PGE1, or PGE2 were tested with PTH. Media obtained by culturing explants of embryonic chick liver, heart and muscle did not have bone resorbing activity. Secretion of the bone resorbing factor by thyroid glands was blocked by Indomethacin (10(-5)M) but the effects of the factor on bone were not blocked by this agent. These results suggest that the thyroid gland is capable of secreting a stimulator of bone resorption, possibly a prostaglandin, which is capable of synergizing with PTH, and which may represent a tissue factor which under certain circumstances may exert an influence on bone.