Gross deletions of the neurofibromatosis type 1 (NF1) gene are predominantly of maternal origin and commonly associated with a learning disability, dysmorphic features and developmental delay

The adherence of either cholera toxin or the heat-labile enterotoxin of Escherichia coli to monosialoganglioside gal(beta1-3)galNAc(beta1-4)[sialic acid (alpha2-3)]gal(beta1-4)glc(beta)1-ceramide (GM1) present on the surface of epithelial cells lining the intestine is the first step of a series that results in the induction of a watery diarrhea. While cholera is more severe, both can lead to death as a result of dehydration. To determine the potential of defined multivalent oligosaccharides, synthesized by the covalent attachment of multiple phenylisothiocyanate (PITC) derivatives of gal(beta1-3)galNAc(beta1-4)[sialic acid(alpha2-3)]gal(beta1-4)glc (oligo-GM1) to the arms of a poly(propylene imine) dendrimer, as therapeutic agents for these diseases, their ability to inhibit adherence of the toxins to cell surface-associated GM1 was determined. They not only inhibited choleragenoid (binding subunit of cholera toxin) binding to GM1-treated NCTC-2071 cells (chemically transformed murine fibroblasts) at 5 degrees, but also inhibited adherence of the choleragenoid, cholera toxin, and heat-labile enterotoxin of E. coli to GM1-treated NCTC-2071 cells at 37 degrees. Inhibition was observed whether the toxin was preincubated with the oligo-GM1-PITC-derivatized dendrimer prior to addition to cells or given just after the addition of the derivatized dendrimer to cells. The derivatized dendrimer had no effect on cell viability, as monitored by trypan blue exclusion. Blue-shifts in tryptophan fluorescence emission spectra maxima induced by adherence of either choleragenoid, cholera holotoxin, or the heat-labile enterotoxin of E. coli to oligo-GM1-PITC-derivatized dendrimers were similar to those induced by adherence to GM1 or oligo-GM1. Comparable shifts were not observed when the toxins were incubated with gangliosides that fail to function as receptors.     

Ligand partitioning into membranes: its significance in determining Km and Ks values for cytochrome P-450 and other membrane bound receptors and enzymes

Enzyme(s) capable of decomposing N-acetylglucosaminyl ribitol teichoic acid prepared from the cell wall of Staphylococcus aureus FDA 209 P was obtained from the culture supernatant of a gram-negative, rod-shaped, spore-forming soil bacterium. Properties of the bacterium were very similar to those of Bacillus circulans.     

Evaluation of an adenosine 5'-triphosphate assay as a screening method to detect significant bacteriuria

The bioluminescent reaction of adenosine 5'-triphosphate (ATP) with luciferin and luciferase has been used in conjunction with a sensitive photometer (Lab-Line's ATP photometer) to detect significant bacteriuria in urine. This rapid method of screening urine specimens for bacteriuria was evaluated by using 348 urine specimens submitted to the clinical microbiology laboratory at the University of Minnesota Hospitals for routine culture using the calibrated loop-streak plate method. There was 89.4% agreement between the culture method and the ATP assay, with 7.0% false positive and 27.0% false negative results from the ATP assay using 10(5) organisms/ml of urine or greater as positive for significant bacteriuria and less than 10(5) organisms/ml as negative for significant bacteriuria.     

Optical technique for the study of convective diffusion from falling drops

A recently developed deflection mapping technique has been exploited for measurement of rate of mass transfer from a liquid drop falling freely in another liquid medium. Results have been found to be in good agreement with theory. Simultaneously, measurement of the diffusion coefficient is also reported.     

Gas-chromatographic analysis for therapeutic concentration of imipramine and disipramine in plasma, with use of a nitrogen detector

We describe a method for the simultaneous gas-chromatographic analysis of imipramine and desipramine (the active N-desmethyl metabolite) at therapeutic concentrations in human plasma, with use of a nitrogen detector. Imipramine is measured as the unchanged base and desipramine as its N-tribluoroacetyl derivative. Promazine is the internal standard. The lower limit of sensitivity is 5 mug/liter for each drug, and the within-day coefficients of variation for the determination of imipramine and desipramine, respectively, are 6.0% and 3.3%. We measured concentrations of these drugs both in patients receiving therapeutic doses of imipramine and in those who had ingested an overdose.     

Floc breakage in agitated suspensions: Effect of agitation rate

A population balance equation that governs the floc size distribution in turbulent flow, incorporating both the splitting and erosion mechanisms of floc breakage has been presented in previous studies[6,7]. Experiments have been conducted in which transient floc size distributions of dilute suspensions of Kaolin-hydrous ferric-oxide flocs undergoing breakage in agitated batch system are obtained over turbulent microscale shear rates ranging from 60 to 400 sec^?1. Floc size distributions over a range of floc diameters from about 1 to 100 μ m are measured by overlapping techniques, including computerized optical scanning of photographs and rapid electronic sizing of individual flocs using a light blockage transducer. The experimentally determined size distributions are then fit to those computed from the population balance equation, using constrained nonlinear least squares. The splitting frequency of parent flocs is found to vary as the 0.33 power of the parent floc volume and 0.71 power of the shear rate. The average number of daughter fragments produced upon splitting of individual flocs is found to be about 2.5. The mean and standard deviation of the daughter fragments produced upon splitting are found to be in fixed ratio to one another, independent of the parent floc size and shear rate. An appropriately nondimensionalized coefficient characterizing floc erosion has been found to be independent of shear rate.     

Middle-ear impedance measurements in screening

Middle-ear disorders are the major cause of hearing loss in the young school child, the majority of sensorineural disorders already having been detected. Mild conductive deafness may lead to educational retardation, psychological and social problems as well as to more severe middle-ear problems. It is consequently important to detect persistent middle-ear conditions as early as possible. Pure-tone audiometry has been shown to be a poor method of identifying middle-ear effusions. Impedance measurement is considerably more efficient, and different approaches are reviewed in the light of long-term studies of middle-ear effusion.     

Extracellular signal-regulated kinase (MAP kinase) immunoreactivity in the rhesus monkey brain

Phosphorylation of both tyrosine and serine residues of focal adhesion kinase (FAK) was stimulated by the adhesion of BALB/c mouse 3T3 cells to fibronectin, but phosphorylation of threonine was not detectable. Acidic and basic fibroblast growth factors also stimulated the phosphorylation of serine and tyrosine of FAK in cells adhered to poly-L-lysine, but epidermal growth factor and platelet-derived growth factor did not. A fusion protein of fibronectin and basic fibroblast growth factor effectively induced the phosphorylation of FAK. Phosphorylation of FAK in the rat myoblast L-6 cell line, which lacks fibroblast growth factor receptors, was not stimulated by fibroblast growth factors, suggesting that the interaction of fibroblast growth factors with their receptors might cause the phosphorylation of FAK.