Modeling of orthokinetic flocculation of Saccharomyces cerevisiae.

This study examined the flocculation behavior of two Saccharomyces cerevisiae strains expressing either Flo1 (LCC1209) genotype or NewFlo (LCC125) phenotype in a laminar flow field by measurement of the fundamental flocculation parameter, the orthokinetic capture coefficient. This orthokinetic capture coefficient was measured as a function of shear rate (5.95-223 s(-1)) and temperature (5-45 degrees C). The capture coefficients of these suspensions were directly proportional to the inverse of shear rate, and exhibited an increase as the temperature was increased to 45 degrees C. The capture coefficient of pronase-treated cells was also measured over similar shear rate and temperature range. A theory, which predicts capture coefficient values due to zymolectin interactions, was simplified from that developed by Long et al. [Biophys. J. 76: (1999) 1112]. This new modified theory uses estimates of: (1) cell wall densities of zymolectins and carbohydrate ligands; (2) cell wall collision contact area; and (3) the forward rate coefficient of binding to predict theoretical capture coefficients. A second model that involves both zymolectin interactions and DLVO forces was used to describe the phenomenon of yeast flocculation at intermediate shear ranges, to explain yeast flocculation in laminar flow.     

Blueberry flavonoids inhibit matrix metalloproteinase activity in DU145 human prostate cancer cells.

Regulation of the matrix metalloproteinases (MMPs), the major mediators of extracellular matrix (ECM) degradation, is crucial to regulate ECM proteolysis, which is important in metastasis. This study examined the effects of 3 flavonoid-enriched fractions (a crude fraction, an anthocyanin-enriched fraction, and a proanthocyanidin-enriched fraction), which were prepared from lowbush blueberries (Vaccinium angustifolium), on MMP activity in DU145 human prostate cancer cells in vitro. Using gelatin gel electrophoresis, MMP activity was evaluated from cells after 24-hr exposure to blueberry fractions. All fractions elicited an ability to decrease the activity of MMP-2 and MMP-9. Of the fractions tested, the proanthocyanidin-enriched fraction was found to be the most effective at inhibiting MMP activity in these cells. No induction of either necrotic or apoptotic cell death was noted in these cells in response to treatment with the blueberry fractions. These findings indicate that flavonoids from blueberry possess the ability to effectively decrease MMP activity, which may decrease overall ECM degradation. This ability may be important in controlling tumor metastasis formation.     

Atp-activated ionic permeability in smooth muscle cells isolated from the guinea pig urinary bladder

Smooth muscle cells from the guinea pig urinary bladder were investigated by voltage clamping at the plasma membrane and using an intracellular perfusion technique. Applying adenosine triphosphate (ATP) at a concentration greater than 3 × 10^–8 M and at a membrane potential of –100 to –30 mV produced a rise in fast inward transmembrane current. A similar effect was exerted by adenosine diphosphate (ADP) and -, -, and ,-methylene ATP. Application of guanosine triphosphate, inosine triphosphate, adenosine monophosphate (AMP), and adenosine failed to activate this current. It was found that AMP blocks ATP receptors competitively. No pharmacological differences were found between the latter ATP receptors and those of rat sensory neurons. The ATP receptors were rapidly desensitized and recovered their sensitivity to agonists extremely slowly. Speed of desensitization was reduced by a decrease in ATP concentration.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 19, No. 1, pp. 95–100, January–February, 1987.     

Fibronectin-degrading proteases from the membranes of transformed cells

The local degradation of fibronectin substrata by Rous sarcoma virus-transformed chick embryonic fibroblasts requires cell-contact-related metalloendoprotease and serine-protease activities. Using fibronectin-containing SDS gels, two large proteases with apparent molecular weights of 120K and 150K were found only in the membrane fraction of transformed cells and were absent in normal cells. Both 120K and 150K proteases were active at neutral pH, but showed preferential inhibitor sensitivities of serine and metal proteases, respectively. The 150K protease appeared to account for most of the proteolytic activity since metalloendoprotease inhibitors completely blocked proteolytic activity of the 150K in fibronectin gels, more than 80% of the fibronectin-degrading activity of solubilized membranes, and largely suppressed the appearance of fibronectin degradation spots in cultures of transformed cells.     

Vaginal treatment with a prostaglandin F2 alpha derivative (alfaprostol) for inducing labor in pregnancy at term

The effectiveness and acceptability of Alfaprostol (an analog of PGF2 alpha) in inducing labor were assessed in 20 pregnant women at term. All subjects had no spontaneous uterine activity before treatment and the mean (M +/- SE) Bishop score was 2.45 +/- 0.21. The drug was administered by vaginal route at the dose of 10 mg every 3 hours. Regular uterine contractions appeared in all patients and delivery occurred in 85% of the patients after a mean time of 9h50min +/- 0h55min following the start of treatment. The mean dose of Alfaprostol utilized to achieve delivery was 29.4 +/- 2.0 mg. No major side effects were noted in the mothers and their fetuses at any time during treatment. Two patients exhibited vomiting. The Apgar score of all newborns at birth was 8 or more. These results suggest the usefulness of Alfaprostol to induce labor in pregnant women at term, as it has oxytocic activity without adverse effects on either the mother or the fetus.     

Temperature regulation in a burrow-nesting tropical seabird,the Wedge-tailed Shearwater (Puffinus pacificus)

Summary At low air temperatures (2.3–13.9°C), Wedge-tailed Shearwaters (Puffinus pacificus) shivered and their oxygen consumption increased to as much as 283% of the mean value (0.77 ml O₂/g·h) within the thermoneutral zone of air temperature (23–34°C). The minimal thermal conductance of the tissues and plumage was similar to the value predicted from the body mass (320.5 g). The oxygen consumption of the birds within their thermoneutral zone was lower than predictions based on body mass. At elevated air temperatures, the shearwaters panted at respiratory frequencies as high as 260 respirations/min; maximal respiratory frequencies were not invoked until the birds had become hyperthermic. During exposure to a hot environment, the oxygen consumption of the birds increased and in most instances the shearwaters were not able to lose heat equivalent to their concurrent metabolic heat production.Symbols and abbreviations BMR basal metabolic rate - C _total total thermal conductance - f respiratory frequency - TEWL total evaporative water loss - T _st stomach temperature - T _re rectal temperature     

The multicomponent analysis of estrogens in urine by ion exchange chromatography and GC-MS--I. Quantitation of estrogens after initial hydrolysis of conjugates

A method for the multicomponent analysis of estrogens in urine after initial hydrolysis of the conjugates is described. Following protection of the carbonyl functions by ethoximation, estrogen conjugates were extracted on Sep-Pak C18 cartridges and purified on the acetate form of DEAE-Sephadex. The samples were subsequently hydrolysed by Helix pomatia juice and the hydrolysate was purified on the acetate form of QAE-Sephadex. Estrogens with vicinal cis-hydroxyls and diphenolic compounds were fractionated on the borate and bicarbonate form of QAE-Sephadex, respectively. Neutral steroids were removed by the free base form of DEAE-Sephadex after which estrogens were separated into two groups using Lipidex 5000 in a straight phase system. Following trimethylsilyl ether derivatization estrogens were analysed by selected ion monitoring (SIM). The method allows the quantitation of all the important estrogen metabolites including catechol estrogens. It is precise, accurate and sensitive permitting the quantitation of estrogens in urine of males and non-pregnant females.     

The probability with which EMS-initiated mutagenic lesions generate mutations in CHO cells

In this note we distinguish between multiple mutations affecting a given locus which are generated at separate error-prone lesions and multiple independent mutations generated at a single error-prone lesion. We describe a basis for determining the probability with which the latter class of mutations occurs based on the mutant fraction in the progeny and determine an average probability of 0.6 mutations/replication/mutagenic site for those EMS-modified sites which are mutagenic for G6PDH activity in CHO cells.