Group I allergens of grass pollen as cell wall-loosening agents

Group I allergens are the major allergens of grass pollen, but their biological function is unknown. These proteins are shown here to be structurally related to expansins, which are able to induce extension (creep) of plant cell walls. Extracts of maize pollen possess potent expansin-like activity, as measured in wall extension and wall stress-relaxation assays. This activity is selective for grass cell walls and is, at least partly, due to the action of maize group I allergens. We propose that group I allergens facilitate invasion of the pollen tube into the maternal tissues by loosening the cell walls of the grass stigma and style. Additionally, the presence of related mRNAs in vegetative tissues of rice, Arabidopsis, and soybean implies that allergen homologs may function to loosen walls in growing vegetative tissues as well.     

Three-dimensional echocardiographic planimetry of maximal regurgitant orifice area in myxomatous mitral regurgitation: intraoperative comparison with proximal flow convergence

The purpose of this study was to evaluate the usefulness of multishot echo-planar imaging in detecting liver tumors in comparison with respiratory triggered T2-weighted fast-spin-echo (FSE) imaging. Thirty-two patients with 70 focal liver lesions were imaged using a 1.5-T high speed MR imager. Eight-shot echo-planar images covering the whole liver were acquired during a single breath-hold period. FSE images were acquired with respiratory triggering in approximately 4 minutes. Lesion detectability and image quality of the two pulse sequences were analyzed qualitatively. Quantitative analysis was performed by means of signal-to-noise and tumor-liver contrast-to-noise analysis. Lesion detectability was comparable in both solid (86.3% vs 90.2%: .3 < P < .5) and nonsolid lesions (89.5% vs 100%: .3 < P < .5) between echo-planar and FSE images. Echo-planar imaging provided significantly reduced image artifact, better lesion conspicuity, and anatomic detail compared with FSE imaging. The signal-to-noise and contrast-to-noise ratios of echo-planar images were significantly higher than those of FSE images. Breath-hold eight-shot echo-planar imaging can be an alternative to T2-weighted FSE imaging because it can provide comparable image quality in a substantially decreased acquisition time.     

Acid-growth response and alpha-expansins in suspension cultures of bright yellow 2 tobacco

The possibility that Bright Yellow 2 (BY2) tobacco (Nicotiana tabacum L.) suspension-cultured cells possess an expansin-mediated acid-growth mechanism was examined by multiple approaches. BY2 cells grew three times faster upon treatment with fusicoccin, which induces an acidification of the cell wall. Exogenous expansins likewise stimulated BY2 cell growth 3-fold. Protein extracted from BY2 cell walls possessed the expansin-like ability to induce extension of isolated walls. In western-blot analysis of BY2 wall protein, one band of 29 kD was recognized by anti-expansin antibody. Six different classes of alpha-expansin mRNA were identified in a BY2 cDNA library. Northern-blot analysis indicated moderate to low abundance of multiple alpha-expansin mRNAs in BY2 cells. From these results we conclude that BY2 suspension-cultured cells have the necessary components for expansin-mediated cell wall enlargement.     

Ultrastructural, physiological, and molecular defects in the inner ear of a gene-knockout mouse model for autosomal Alport syndrome

It is well documented that damage to the chick cochlea caused by acoustic overstimulation or ototoxic drugs is reversible. Second-order auditory neurons in nucleus magnocellularis (NM) are sensitive to changes in input from the cochlea. However, few experiments studying changes in NM during cochlear hair cell loss and regeneration have been reported. Chicks were given a single systemic dose of gentamicin, which results in maximal hair cell loss in the base of the cochlea after 5 days. Many new hair cells are present by 9 days. These new hair cells are mature but not completely recovered in organization by 70 days. We counted neurons in Nissl-stained sections of the brainstem within specific tonotopic regions of NM, comparing absolute cell number between gentamicin- and saline-treated animals at both short and long survival times. Our data suggest that neuronal number in rostral NM parallels hair cell number in the base of the cochlea. That is, after a single dose of gentamicin, we see a loss of both cochlear hair cells and NM neurons early, followed by a recovery of both cochlear hair cells and NM neurons later. These results suggest that neurons, like cochlear hair cells, can recover following gentamicin-induced damage.     

Association of calcium channel blocker use with increased rate of acute myocardial infarction in patients with left ventricular dysfunction

The Studies of Left Ventricular Dysfunction (SOLVD) assessed the effect of enalapril in patients with systolic left ventricular dysfunction (LVD). We performed retrospective analyses of the association between calcium channel blocker (CCB) use and fatal and nonfatal myocardial infarction (MI) in these patients. MI occurred in 11.5% of 845 patients receiving CCBs versus 7.5% of 2551 patients not receiving CCBs in the enalapril group and in 14.4% of 874 patients receiving CCBs versus 9.3% of 2527 patients not receiving CCBs in the placebo group. By multivariate Cox regression analysis, adjusting for comorbidity, cause and severity of LVD, heart failure, and concomitant drug use, CCB use was an independent predictor of MI (relative risk [RR] 1.37, confidence interval [CI] 1.14 to 1.63). The increase in MI risk was greater among patients with a higher heart rate (RR 1.46, CI 1.14 to 1.86) and lower blood pressure (RR 1.45, CI 1.14 to 1.86). The adjusted risk ratio for all-cause mortality associated with CCB use was 1.14 (CI 1.00 to 1.28; p = 0.0454). In this analysis of patients with LVD, CCB use was associated with significantly increased risk of fatal or nonfatal MI.     

Expression of basement membrane type IV collagen chains during postnatal development in the murine cochlea

An immunofluorescence study was performed to examine the temporal and spatial patterns of expression for the different type IV collagen chains during postnatal cochlear development. At birth, the classical chains (4A1 and 4A2) were widely expressed, while the novel chains (4A3, 4A4, and 4A5) were completely absent. Activation of the novel chains was observed at 4 days of age, with intense, widely distributed immunostaining suggesting that most of the cells in the cochlea express the novel chains at this developmental stage. From day 8 through day 14, developmental inactivation of the novel chains results in a reduction of generalized immunoreactivity with a concomitant elevation of specific staining in the membranous structures bounding the interdental cells of the spiral limbus, the inner sulcus, the basilar membrane, and in a fibrous bed of staining radiating from the spiral prominence into the region of the spiral ligament which corresponds to the location of the root cell processes. This pattern of intense immunostaining for the novel chains persists through adulthood. The classical chains are expressed in these same anatomical regions only transiently (from day 6 to day 10), after which a gradual developmental inactivation leads to the adult expression pattern where classical collagen chains are found primarily in the perineurium, in the membranes surrounding the spiral ganglion cell bodies, and in the vascular basement membranes of the spiral ligament and the stria vascularis. The complex developmental pattern of expression for the type IV collagen chains in the murine cochlea is similar to that observed in the murine kidney, which is the other major site for basement membrane pathology in Alport syndrome.     

Coagulase-negative staphylococcal sternal wound infections after open heart operations

Buffalo erythrocytes contain one isozyme of hexokinase that apparently lacks microheterogeneity as shown by chromatographic properties. A single protein band was detected by means of Western blotting using an antibody raised in rabbits against homogeneous rat brain hexokinase I. The native protein has a molecular weight of 200,000 +/- 2880 by gel filtration. Partial purification of erythrocyte hexokinase by a combination of several procedures, including affinity chromatography, which was previously applied successfully to the purification of other mammalian type I hexokinases, produced a partially purified enzyme that showed several contaminants after SDS-polyacrylamide gel electrophoresis. The affinity of buffalo erythrocyte hexokinase for glucose (K(m) = 0.012 +/- 0.001 mM) is lower than most other mammal hexokinases type I. It phosphorylates other sugars, with considerably higher K(m) values. This isozyme is able to use MgATP but does not use MgGTP, MgCTP or MgUTP. We used inhibition patterns, obtained with products to elucidate enzyme sequential mechanisms. Our results are clearly in agreement with a random sequential mechanism and in disagreement with an ordered sequential mechanism with either glucose or ATP as the obligatory first substrates. The ADP inhibition was of mixed type with both ATP and glucose as substrates.     

Formal endoscopy training for senior and junior house staff

The upper endoscopic experience of junior and senior surgical residents was analyzed before (period 1) and after (period 2) creating a 2-month rotation with a dedicated surgical endoscopist. Three hundred sixty-two endoscopies were performed during the study period, with 295 (81%) being performed after formalizing training. A chi-square analysis was performed and found to be statistically significant for each group when compared to a control experience with colonoscopy. We conclude that a dedicated block of time and a committed surgical attending physician will have a significantly positive impact on resident caseload. Furthermore, the added benefits of being more closely involved with the patient rather than relying on another discipline will add to the resident's educational experience.     

The use of block copolymer stabilizers for controlling dispersion stability

The role of block copolymers in stabilizing colloidal dispersions against flocculation or coalescence is discussed in terms of the detailed structure of the interface. Both particulate dispersions and liquid/liquid interfaces are used as examples. Two novel experimental methods are introduced, small-angle neutron scattering and neutron reflection. Comparison with the Scheutjens Fleer theory for block copolymers is also presented. Strategies for the optimum design of the stabilizing polymer are introduced.