Effects of cell swelling on fluid flow across alveolar epithelium

The effects of decreased temperature, metabolic inhibition, and hyposmolality on osmotically and hydrostatically driven water flux across bullfrog alveolar epithelium were studied. Lungs were isolated from double-pithed Rana catesbeiana and prepared as sacs. Either an osmotic (0.1 M raffinose) or hydrostatic (6.3-6.6 Torr) pressure gradient was imposed across the tissue. These gradients resulted in the volume flow of water from the alveolar to pleural bath. Control water flux and hydraulic conductivity were estimated from the rate of weight loss of the lung sac. Subsequently water flux and hydraulic conductivity were determined under one of the following conditions: 1) temperature of bathing solutions lowered to 2 degrees C; 2) 1 mM 2,4-dinitrophenol added to both alveolar and pleural baths, or 3) both baths changed to half-isosmotic Ringer solution. The control hydraulic conductivities for osmotic (Lpo) and hydrostatic (Lph) pressure gradients were 3.65(+/- 0.94) X 10(-12) and 2.14(+/- 0.63) X 10(-10) ml/dyn X s, respectively. Under conditions of metabolic inhibition, hyposmolality, and decreased temperature, Lph decreased by 77, 83, and 92%, and Lpo decreased by 56, 34, and 59%, respectively. These results are most consistent with the hypothesis that the decrements in hydraulic conductivity under our experimental conditions are due to epithelial cell swelling and perhaps to changes in the characteristics of the paracellular pathway.     

Effects of external loading on short term power output in children and young male adults

The effects of external loading, in the form of small weights distributed evenly over the limbs and torso, on physical performance and power output have been studied during vertical jumping in 10 children and four young adults and the results compared with maximal cycling. The results show under control (unloaded) conditions the absolute peak power output (W) achieved by children and adults was 572 W (45%) and 765 W (25%) respectively higher in cycling than jumping. The addition of weights during jumping served only to increase this difference. External loading produced a linear decrease of W in both groups of subjects. The reduction in W was entirely due to a decrease of take-off velocity (VT). The relationship between VT and added weights (delta wt) could be described by the equations: VT (ms-1) = 1.91 - 0.042 delta wt (kg); r = -0.96 (children); VT (ms-1) = 2.49 - 0.021 delta wt (kg); r = -0.99 (adults). Thus, contrary to the recent work of Caiozzo and Kyle (1980) which involved stair-climbing, body size and speed of movement in children and young adults would appear to be optimally matched for the production of lifting work during vertical jumping. External loading reduces the generation of power output immediately prior to take-off of a maximal jump from a force platform.     

Alteration by estrogen of the nucleoli in nerve cells of the rat hypothalamus

Summary Estrogen is accumulated from the blood by nerve cells in the ventromedial nucleus of the hypothalamus and can facilitate female reproductive behavior by acting on this region of the brain. This cell group was examined in ovariectomized female rats, given estrogen or control treatment, by use of light and electron microscopy. A significantly greater portion of the nerve cells in the estrogen-treated animals had protuberances on their nucleolar surfaces, apparent under the light microscope. The fine structure of such protuberances included dense, aggregated material, which is shown to contain DNA by the sodium tungstate staining technique. Because increased numbers of such protuberances were found in nuclei of cells of the experimental group where previous studies demonstrated a significant increase in ultrastructural signs of biosynthetic activity, they may be associated with increased RNA synthesis. Thus, they could indicate, ultrastructurally, increased synthetic rates for RNA in nerve cells through which estrogen promotes reproductive behavior.     

Isolation of cDNA and genomic DNA clones encoding type II collagen.

A cDNA library constructed from total chick embryo RNA was screened with an enriched fraction of type II collagen mRNA. Two overlapping cDNA clones were characterized and shown to encode the COOH propeptide of type II collagen. In addition, a type II collagen clone was isolated from a Charon 4A library of chick genomic fragments. Definitive identification of the clones was based on DNA sequence analysis. The 3' end of the type II collagen gene appears to be similar to that of other interstitial collagen genes. Northern hybridization data indicates that there is a marked decrease in type II collagen mRNA levels in chondrocytes treated with the dedifferentiating agent 5-bromodeoxyuridine. The major type II collagen mRNA species is 5300 bases long, similar to that of other interstitial collagen RNAs.     

Resonance Raman-spectroscopic studies of the hapten features involved in the binding of 2,4-dinitrophenyl haptens by the mouse myeloma proteins MOPC 315 and MOPC 460.

The binding of four dinitrophenyl haptens to the mouse myeloma proteins MOPC 315 IgA (immunoglobulin A) and MOPC 460IgA was studied by resonance Raman spectroscopy. Isotopic substitution with 15N and 2H was used to assign features in the resonance Raman spectra of the free haptens. Changes in each of these features on binding to the proteins could then be attributed to interactions of the proteins' binding sites with either the p-NO2 or the o-NO2/amine regions of the haptens. The interactions between a given hapten and MOPC 315 IgA are often quite distinct from those between the same hapten and MOPC 460 IgA. Moreover, for both antibodies the nature of the R side chain in a Dnp-NHR (Dnp, 2,4-dinitrophenyl) compound appears to modify the interactions between the Dnp chromophore and the protein. Thus, with the haptens studied, there is no unique set of contacts between the Dnp group and the binding site. The contacts expected between epsilon-2,4-dinitrophenyl-L-lysine and the site on MOPC 315 IgA, on the basis of a recent model for this site [Dwek, Wain-Hobson, Dower, Gettins, Sutton, Perkins & Givol (1977) Nature (London) 266, 31--37] were not detected. However, the contacts between this hapten and the site on MOPC 460 IgA were closer to those predicted by the model for MOPC 315 IgA.     

Interaction of the DNA untwisting enzyme with the SV40 nucleoprotein complex.

The SV40 nucleoprotein complex which was isolated from infected CV-1 cells did not possess an active DNA untwisting enzyme. The superhelix density of the DNA in the chromatin complex was unchanged after treatment with purified rat liver DNA untwisting enzyme. However, in the presence of ethidium bromide (1 microgram/ml) the superhelix density was changed. Moreover, the nicked intermediate in the DNA untwisting reaction could be detected using the chromatin DNA as a substrate. These results show that the DNA in the SV40 chromatin which is accessible to the DNA untwisting enzyme is under no topological strain.     

The staging and treatment of epithelial ovarian cancer.

Recent advances in the staging of ovarian cancer have suggested that many patients with apparently localized (stage I or II) disease have occult dissemination within the abdomen. Approximately 20% of patients classified at laparotomy as having stage I or II ovarian cancer are found by lymphangiography to have abnormal retroperitoneal lymph nodes. In many other patients advanced disease is also detected by peritonescopy; with this technique metastases are often discovered on the undersurface of the right diaphragm. These findings may help explain the high rates of recurrence after surgical resection or pelvic irradiation, or both, in patients with localized disease. Studies are in progress to determine whether modification of the radiotherapy field to include the right diaphragm will improve survival. Along with improved staging, histologic grading of the degree of anaplasia of the tumour tissue may permit more precise determination of prognosis and therefore better design of therapy. Adjuvant radiotherapy has not yet been shown to improve the survival of patients with stage I disease, but the 5-year survival of patients with stage II disease is greater for those receiving postoperative radiotherapy than for those undergoing surgery alone. For most patients with advanced disease radiotherapy is palliative only and carries a high risk of long-term complications. Numerous chemotherapeutic agents used singly can produce an objective response by tumour. Preliminary data suggest that combination chemotherapy can increase the rate of objective response, but a longer follow-up period is necessary to determine whether this form of therapy can improve survival.