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.     

The taxonomic status, distribution and conservation of the lowland anoa Bubalus depressicornis and mountain anoa Bubalus quarlesi

1. The anoas are two species of dwarf buffalo, the lowland anoa Bubalus depressicornis and mountain anoa Bubalus quarlesi that are endemic to the island of Sulawesi, Indonesia. The classification of the subgenus Anoa within Bubalus is upheld by assessment of recent genetic and morphological research. The classification of anoas into two species is still debated, but with the absence of significant opposing evidence, this position is adopted here. 2. Information about the distribution of the two species is presented that adds to but largely supports existing reports. However, it is still uncertain whether the two putative species are sympatric or parapatric in their distribution. A review of anoa distribution from historical reports and recent field data (1990s to 2002) highlights their decline throughout Sulawesi, especially in the southern and north-eastern peninsulas. The decline has been attributed to local hunting for meat and habitat loss. Most populations are rapidly becoming fragmented, suggesting that the conservation of viable populations may eventually require management of metapopulations. 3. There is an urgent requirement for conservation efforts to: (i) protect anoas from hunting; (ii) prevent habitat loss in key sites; (iii) complete genetic studies to better determine the number of anoa taxa and Management Units and assess their distribution; and (iv) determine the status of the remaining anoa populations.     

Gastroduodenal ulceration following active immunization with prostaglandin E2 in dogs. Role of gastric acid secretion

In this study we present evidence to suggest that gastroduodenal mucosal defects may occur in gastric fistula dogs actively immunized with PGE2-thyroglobulin conjugate. One of four PGE2-immunized dogs developed a chronic pyloroduodenal ulcer with penetration into the pancreas and the other three had endoscopic evidence of gastric and/or duodenal erosions. In contrast, no gastroduodenal mucosal defects were seen in control dogs immunized with thyroglobulin alone. Occurrence of gastroduodenal ulcers or erosions was temporally related to formation of specific antibody to PGE2 suggesting that PGE2 antibody may be responsible for lesion formation. An increase in gastric acid secretion was not observed in PGE2-immunized dogs. Thus, it is likely that mucosal defects occur as a result of an impairment of PGE2-mediated mucosal defense mechanisms. Since gastroduodenal lesions can be visualized by endoscopy, the dog may prove to be useful in studying the role of endogenous PG in ulcer diseases.     

Transpososomes: stable protein-DNA complexes involved in the in vitro transposition of bacteriophage Mu DNA

We report that two types of stable protein-DNA complexes, or transpososomes, are generated in vitro during the Mu DNA strand transfer reaction. The Type 1 complex is an intermediate in the reaction. Its formation requires a supercoiled mini-Mu donor plasmid, Mu A and HU protein, and Mg2+. In the Type 1 complex the two ends of Mu are held together, creating a figure eight-shaped molecule with two independent topological domains; the Mu sequences remain supercoiled while the vector DNA is relaxed because of nicking. In the presence of Mu B protein, ATP, target DNA, and Mg2+, the Type 1 complex is converted into the protein-associated product of the strand transfer reaction. In this Type 2 complex, the target DNA has been joined to the Mu DNA ends held in the synaptic complex at the center of the figure eight. Supercoils are not required for the latter reaction.     

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.     

Critical considerations in the development of an assay for sulfidopeptide leukotrienes in plasma

A sensitive and specific assay has been developed for measurement of total sulfidopeptide leukotrienes (LT) in plasma. LTC4 and LTD4 in plasma are converted to LTE4 which is then extracted by C18 Sep-Pak binding and elution. Total LTE4 is resolved by reverse phase high performance liquid chromatography (RP-HPLC) and quantitated by radioimmunoassay (RIA). A [3H]LTE4 internal standard is added to the starting plasma sample to allow overall recovery to be calculated and to define the fractions from RP-HPLC to be assayed for LTE4-like immunoreactivity. The correlation between the measured increase in LTE4 concentration after addition of incremental amounts of LTC4 and LTE4 to plasma was 0.989 and 0.978, respectively, with slopes of 1.05 and 1.11. Addition of 51 pg/ml LTE4 to 5 ml plasma was detectable; the measured increase was 48 +/- 12 pg/ml (mean +/- SE, n = 7). The intra-assay coefficient of variation for 341 pg/ml of added LTC4 was 3.2% (n = 6). Sulfidopeptide leukotrienes could not be detected in blood samples taken from 12 normal volunteers in whom the theoretical detection limit, calculated from the sensitivity of the RIA, the overall recovery of LTE4, and the volume of plasma extracted, was 83 +/- 4 pg LTE4/ml plasma (0.19 +/- 0.01 pmol sulfidopeptide leukotriene/ml plasma; mean +/- SE).     

Tracheostomy Tube Failure in Obstructive Sleep Apnea

In our institutions we routinely do posttracheostomy sleep studies on patients being treated for obstructive sleep apnea. We have identified several patients who failed to show objective evidence of improvement after tracheostomy. From our studies we have found that both mechanical obstruction and concomitant respiratory control dysfunction caused this failure. A unique tracheostomy tube was constructed to treat the subset of patients with internal collapse of the tracheostomy tube.     

An abnormal terminal X-Y interchange accounts for most but not all cases of human XX maleness

To determine if human XX maleness results from an abnormal chromosomal X-Y interchange, we studied the inheritance of the paternal pseudoautosomal region in nine patients. Those six patients in whom Y-specific DNA was found (Y(+)) inherited the entire pseudoautosomal region from the paternal Y chromosome and lost that of the paternal X chromosome. Moreover, in three Y(+) cases, we observed the deletion of a paternal Xp locus tightly linked to the pseudoautosomal region. These results definitively show that an abnormal and terminal X-Y interchange during paternal meiosis causes Y(+)XX maleness. In contrast, no abnormal X-Y interchange was observed in any of the three Y(-) cases analyzed, suggesting that maleness can occur in the absence of any Y-specific DNA.