Cervical cytology quality assurance in Washington State.

The objectives of this study were to establish a profile of cervical cytology laboratories in Washington State, identify quality assurance problems amenable to correction through education or legislation, and describe differences between large and small cytology laboratories. All 43 Washington laboratories that perform cervical cytology were surveyed by mail during 1989. Completed surveys were returned by 37 (86%) of the laboratories. Nearly half (43%) of the respondents reported processing less than 10,000 Papanicolaou smears annually. Only one-third (35%) of the respondents reported participating in relevant proficiency programs. A proportion of smaller cytology laboratories were compensating their cytotechnologists on the basis of the number of slides read and allowing Papanicolaou smears to be read outside the confines of the laboratory. The results of this study suggest that cytotechnologists in some larger Washington laboratories have been exceeding work load limits recommended by professional associations. Recent legislation includes regulations that address cervical cytology quality assurance. However, continued efforts will need to be made to encourage voluntary adoption of quality control measures not addressed by this legislation.     

Spatial pattern,regeneration and growth rates of Brachystegia spiciformis and Julbernardia globiflora

Past work on tree-to-tree interactions in semi-arid savannas, through the use of nearest neighbour analysis, has shown both a regular dispersion pattern and a positive correlation between the size of a tree and the distance to its nearest neighbour. From these results, the importance of competition has been inferred. In the present study, tree-to-tree interactions in a mesic savanna woodland at Marondera, Zimbabwe, dominated by relatively small-sized individuals of Brachystegia spiciformis and Julbernardia globiflora, were examined. Results show that the regular dispersion pattern is uncommon; that there are few significant positive correlations between size of individual and distance to nearest neighbour; and that growth rate is not consistently correlated with size and distance of nearest neighbour. Results of a study of regeneration relative to canopy cover suggest a possible mechanism for these findings: unlike semi-arid savannas, young plants often grow in under-canopy environments so that early spacing of young trees does not occur. Significant positive correlations between the size of a tree and the distance to its nearest neighbour were found in a stand of larger, presumably older, trees, suggesting that such a relationship only develops in mesic miombo woodland through a thinning process as the trees mature. Familial clumping, which is common in the study area, may mask spatial patterns.Abbreviations RBAI Relative basal area increment     

Morphological responses by Bosmina longirostris and Eubosmina tubicen to changes in copepod predator populations during a whole-lake acidification experiment

Changes in zooplankton populations during the experimental acidilicationof Little Rock Lake provided an opportunity to examine specificmechanisms underlying the morphological responses of bosminidsto changing predation pressure. Two large copepods, Epischuralacustris and Mesocyclops edax, disappeared from the lake'sacidified basin in 1986 and 1989, respectively, while a smallercopepod predator, Tropocyclops extensus, increased during laterstages of acidification. The two bosminid species showed distinctlydifferent responses coinciding with the changes in copepod predation.Bosmina longirostris exhibited a significant decrease in mucrolength with the decline of M.edax and E.lacustris. Its meanbody and antennule length, however, did not change. We suggestthat the decoupling of B.longirostris mucro length and antennulelength may have been related to the persistence of the smallercopepod predator, T.extensus. Eubosmina tubicen showed no apparentresponse to declines in M.edax and E.lacustris abundance ineither mean mucro, antennule or body length. Allometric analysesindicated, however, that mucro length was related to size-dependentcopepod predation for both B.longirostris and E.tubicen.     

Studies on the binding of integration host factor (IHF) and TraM to the origin of transfer of the IncFV plasmid pED208

The origin of transfer (oriT) of the IncFV plasmid pED208 contains a region with three binding sites for both the plasmid-encoded TraM protein and the integration host factor (IHF) of Escherichia coli, a sequence-specific DNA-binding protein. One region, containing overlapping TraM and IHF binding sites, could be interpreted as containing two binding sites for each protein. Using gel retardation assays, an affinity constant for IHF binding to the three main sites was estimated in the presence and absence of 0.1 M potassium glutamate, which increased the avidity of IHF binding to the weaker sites by two orders of magnitude. DNase I protection analyses and electron microscopy were used to determine the affinity of IHF for oriT-containing DNA in the presence and absence of TraM. The binding of IHF and TraM was found to be non-cooperative by the two techniques employed. Electron microscopy also demonstrated that IHF bent the oriT region in a manner consistent with its previously determined mode of action, while TraM had no discernible effect on the appearance of the DNA. This suggested that IHF and TraM interact with a 295 by sequence in the oriT region and organize it into a higher order structure that may have a role in the initiation of DNA transfer and control of traM expression.     

Relation between osmolality of diet and gastrointestinal side effects in enteral nutrition.

One hundred and eighteen patients with normal gastrointestinal function were randomly allocated to one of three feeding regimens in a double blind study to determine the relation between the tonicity of the diet and gastrointestinal side effects related to the diet and to evaluate the efficacy of "starter" regimens in reducing gastrointestinal side effects during enteral nutrition. Patients received a hypertonic diet with an osmolality of 430 mmol (mosmol)/kg (group 1), the same diet but with the osmolality increasing from 145 to 430 mmol/kg over the first four days (group 2), or an isotonic diet (300 mmol/kg) (group 3). All diets were prepared aseptically and administered by 24 hour nasogastric infusion. The mean daily nitrogen intake in group 1 was significantly greater (p less than 0.05) than that in both groups 2 and 3, and the mean overall daily nitrogen balance was significantly better (p less than 0.05) in group 1 than groups 2 and 3. The incidence of side effects related to the diet was similar in all three groups, but diarrhoea was significantly (p less than 0.001) associated with concurrent treatment with antibiotics. These findings show that undiluted hypertonic diet results in significantly better nitrogen intake and balance, that starter regimens reduce nutrient intake but not symptoms, and that diarrhoea is significantly related to treatment with antibiotics and not to administration of an undiluted hypertonic polymeric diet.     

Fulminating necrotizing amebic colitis with perforation: case report and review.

A seriously ill patient with diffuse abdominal tenderness of unknown cause is described. The diagnosis proved to be fulminating necrotizing amebic colitis with perforation. This case report serves as a reminder that amebiasis may occur in patients who have not been outside Canada, that it may readily be confused with other types of inflammatory bowel disease, and that particular care should be taken in obtaining a history of exposure. Before inflammatory bowel disease is diagnosed not only should the usual diagnostic tests such as stool examination and mucosal biopsy be done, but also serologic testing for amebiasis should be carried out.     

Identification of the Ca(2+)-independent endocytic hyaluronan receptor in rat liver sinusoidal endothelial cells using a photoaffinity cross-linking reagent.

The Ca(2+)-independent endocytic hyaluronan (HA) receptor in rat liver sinusoidal endothelial cells (LECs) was identified using a novel cross-linking derivative of HA. The heterobifunctional, photoactivatable, reducible reagent sulfosuccinimidyl 2-(p-azidosalicylamido)ethyl-1,3'-dithiopropionate (SASD) was coupled to the terminal amino group of uniquely modified HA-amine oligosaccharides (M(r) approximately 60,000) and subsequently iodinated. 125I-ASD-HA bound to cultured LECs with similar specificity and affinity as a previously characterized 125I-HA-amine/Bolton-Hunter adduct. Permeabilized LECs were incubated with 125I-ASD-HA with 10 mM EGTA and photolysed with UV light. Detergent extracts were reduced to release the HA oligosaccharides and radiolabeled proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Two polypeptides were consistently and equally labeled at M(r) = 175,000 and 166,000. Photoaffinity labeling of these two proteins was virtually identical in cultured LECs or membranes and was competed greater than 90% with a 100-fold excess of HA. As with the previously characterized bona fide LEC HA receptor, cross-linking was also competed by chondroitin sulfate and heparin, but less efficiently by chondroitin and not with galacturonan. We conclude that the Ca(2+)-independent LEC HA receptor is composed of at least two polypeptides of M(r) approximately 175,000 and 166,000 and may exist as a heterodimer of M(r) approximately 340,000. We also conclude that the LEC HA receptor is distinct from the CD44 family of HA-binding proteins.     

Developmentally regulated lectin in dark versus white axolotl embryos

The white mutant of the Mexican axolotl, A. mexicanum, involves an ectodermal defect which prevents melanophore colonization. Endogenous lectins have been suggested to function in neural crest-derived melanophore adhesion in other animals. To determine if differences in endogenous lectins exist in dark and white axolotls during melanophore colonization, white and dark ectoderm and carcass tissues have been assayed for lectin activity at premigratory, early migratory, and late migratory neural crest stages. Lectin content (specific for D-glucosamine, N-acetyl-D-glucosamine and D-mannose) increases significantly during early migration only in dark ectoderm and white carcass tissues, whereas white ectoderm and dark carcass lectin activities remain close to premigration levels. Neural crest cells in these embryos are associated with regions of high lectin activity suggesting that the differences in endogenous lectins may be involved in establishment of the dark/white phenotype.