Influence of tidal volume on respiratory compliance in anesthetized infants and young children

Recent studies have suggested a close association between total respiratory compliance (Crs) and tidal volume in anesthetized paralyzed infants who are being artificially ventilated. To investigate this further, the multiple occlusion technique was used to measure Crs in 20 anesthetized infants and young children (aged 1-25 mo) before elective surgery. Measurements were made after intubation 1) during spontaneous breathing (SB), 2) after administration of a non-depolarizing muscle relaxant with tidal volume and frequency mimicking that during SB, and 3) with the child still paralyzed but tidal volume approximately double that during SB. Compared with values obtained during SB, there was no significant change in Crs after paralysis when ventilation matched the child's own pattern (P greater than 0.2). When ventilated with the larger tidal volumes, the infants showed a highly significant increase in Crs (mean 62%, range 14-158%, P less than 0.0001). These results may have implications not only for studies performed during anesthesia but also when infants were monitored in the intensive care setting. Values of Crs obtained in ventilated infants may reflect both the mechanical behavior of the respiratory system and the pattern of ventilation at the time of measurement.     

Muralytic Activities of Ruminococcus albus 8

Ruminococcus albus 8 was cultured with isolated alfalfa cell walls as the carbon source. The culture broth was assayed for muralytic enzyme activities. The effect, with respect to the production of such muralytic enzymes, of growing the microorganism on different carbon sources was also investigated. Also, the rates of solubilization and utilization by R. albus of individual alfalfa cell wall sugars during a 96-h growth period were examined.     

Effect of 3-Phenylpropanoic Acid on Capsule and Cellulases of Ruminococcus albus 8

The morphology and cellulases of Ruminococcus albus 8 were markedly affected by the inclusion of 3-phenylpropanoic acid (PPA) in a defined growth medium. PPA-grown bacteria produced substantial quantities of cell-bound cellulase, as well as a very high-molecular-weight extracellular enzyme and lesser amounts of two low-molecular-weight enzymes. PPA-deprived bacteria produced greater total amounts of cellulase, but all of it exists in soluble, low-molecular-weight forms. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the availability of PPA did not affect the kinds of proteins produced, but the distribution of two major proteins between cells and supernatant was PPA dependent. These two proteins (85 and 102 kilodaltons) were primarily associated with the cells of PPA-grown bacteria but were found chiefly in the supernatants of PPA-deprived cultures. Examination of thin sections of PPA-grown R. albus 8 by transmission electron microscopy showed a lobed ruthenium red-staining capsule surrounding the cell wall, as well as small vesicular structures (diameter, 0.05 to 0.06 μm) which appeared to aggregate into larger spherical units (diameter, 0.2 to 0.3 μm). In contrast, thin sections of PPA-deprived cells were devoid of vesicles and showed little or no capsule surrounding the cells.     

Some chemical and physical properties of extracellular polysaccharides produced by Butyrivibrio fibrisolvens strains.

Most strains of Butyrivibrio fibrisolvens are known to produce extracellular polysaccharides (EPs). However, the rheological and functional properties of these EPs have not been determined. Initially, 26 strains of Butyrivibrio were screened for EP yield and apparent viscosities of cell-free supernatants. Yields ranged from less than 1.0 to 16.3 mg per 100 mg of glucose added to the culture. Viscosities ranged from 0.71 to 5.44 mPa.s. Five strains (CF2d, CF3, CF3a, CE51, and H10b) were chosen for further screening. The apparent viscosity of the EP from each of these strains decreased by only 50 to 60% when the shear rate was increased from 20 to 1,000 s-1. Strain CE51 produced the EP having the highest solution viscosity. A detailed comparison of shear dependency of the EP from strain CF3 with xanthan gum showed that this EP was less shear sensitive than xanthan gum and, at a shear rate of 1,000 s-1, more viscous. EPs from strains CF3 and H10b were soluble over a wide range of pH (1 to 13) in 80% (vol/vol) ethanol-water or in 1% (wt/vol) salt solutions. The pH of 1% EP solutions was between 4.5 and 5.5. Addition of acid increased solution viscosities, whereas addition of base decreased viscosity. EPs from strains CF3, CE51, and H10b displayed qualitatively similar infrared spectra. Calcium and sodium were the most abundant minerals in the three EPs. The amounts of magnesium, calcium, and iron varied considerably among the EPs, but the potassium contents remained relatively constant.     

Two-dimensional spreads of synaptonemal complexes from solanaceous plants. I. The technique

Using beta-glucuronidase the cell walls of tomato and potato primary microsporocytes can be digested. When the resulting protoplasts are exposed to distilled water, they burst, and complete sets of synaptonemal complexes are released to settle on plastic coated slides. After drying and formalin fixation, the synaptonemal complexes can be stained with silver or phosphotungstic acid and observed in the light and/or electron microscope. Silver staining gives better contrast for both light and electron microscopy but stains only lateral elements and kinetochores. Phosphotungstic acid staining gives little or no contrast for light microscopy, but stains both the lateral and central elements of the synaptonemal complex, kinetochores, and structures that are probably recombination nodules for electron microscopy. This technique offers a powerful tool for genome analysis by allowing (1) the determination of relative and absolute lengths of synaptonemal complexes and chromosome arm ratios at pachytene, (2) the analysis of complex patterns of synapsis, and (3) the location of what are probably recombination nodules along the length of synaptonemal complexes.     

Production of xanthomegnin and viomellein by isolates of Aspergillus ochraceus, Penicillium cyclopium, and Penicillium viridicatum.

Fungal isolates from legumes were cultured on rice and examined for production of the toxic mold metabolites xanthomegnin and viomellein. Six of 14 Aspergillus ochraceus isolates produced from 0.3 to 1.3 mg of xanthomegnin per g and 0.1 to 1.0 mg of viomellein per g. One of nine isolates of Penicillium cyclopium produced 0.1 mg of xanthomegnin per g and 0.06 mg of viomellein per g. Three of nine P. viridicatum isolates produced from 0.4 to 1.6 mg of xanthomegnin per g and 0.2 to 0.4 mg of viomellein per g. This is the first report of xanthomegnin and viomellein production by A. ochraeus and P. cyclopium.     

Development and validation of genetic markers for sex and cannabinoid chemotype in Cannabis sativa L.

Hemp (Cannabis sativa L.) is an emerging dioecious crop grown primarily for grain, fiber, and cannabinoids. There is good evidence for medicinal benefits of the most abundant cannabinoid in hemp, cannabidiol (CBD). For CBD production, female plants producing CBD but not tetrahydrocannabinol (THC) are desired. We developed and validated high‐throughput PACE (PCR Allele Competitive Extension) assays for C. sativa plant sex and cannabinoid chemotype. The sex assay was validated across a wide range of germplasm and resolved male plants from female and monoecious plants. The cannabinoid chemotype assay revealed segregation in hemp populations, and resolved plants producing predominantly THC, predominantly CBD, and roughly equal amounts of THC and CBD. Cultivar populations that were thought to be stabilized for CBD production were found to be segregating phenotypically and genotypically. Many plants predominantly producing CBD accumulated more than the current US legal limit of 0.3% THC by dry weight. These assays and data provide potentially useful tools for breeding and early selection of hemp.     

Impact of Laminitis on the Canonical Wnt Signaling Pathway in Basal Epithelial Cells of the Equine Digital Laminae

The digital laminae is a two layer tissue that attaches the distal phalanx to the inner hoof wall, thus suspending the horse''s axial skeleton in the hoof capsule. This tissue fails at the epidermal:dermal junction in laminitic horses, causing crippling disease. Basal epithelial cells line the laminar epidermal:dermal junction, undergo physiological change in laminitic horses, and lose versican gene expression. Versican gene expression is purportedly under control of the canonical Wnt signaling pathway and is a trigger for mesenchymal-to-epithelial transition; thus, its repression in laminar epithelial cells of laminitic horses may be associated with suppression of the canonical Wnt signaling pathway and loss of the epithelial cell phenotype. In support of the former contention, we show, using laminae from healthy horses and horses with carbohydrate overload-induced laminitis, quantitative real-time polymerase chain reaction, Western blotting after sodium dodecylsulfate polyacrylamide gel electrophoresis, and immunofluorescent tissue staining, that positive and negative regulatory components of the canonical Wnt signaling pathway are expressed in laminar basal epithelial cells of healthy horses. Furthermore, expression of positive regulators is suppressed and negative regulators elevated in laminae of laminitic compared to healthy horses. We also show that versican gene expression in the epithelial cells correlates positively with that of β-catenin and T-cell Factor 4, consistent with regulation by the canonical Wnt signaling pathway. In addition, gene and protein expression of β-catenin correlates positively with that of integrin β4 and both are strongly suppressed in laminar basal epithelial cells of laminitic horses, which remain E-cadherin⁺/vimentin⁻, excluding mesenchymal transition as contributing to loss of the adherens junction and hemidesmosome components. We propose that suppression of the canonical Wnt signaling pathway, and accompanying reduced expression of β catenin and integrin β4 in laminar basal epithelial cells reduces cell:cell and cell:basement membrane attachment, thus, destabilizing the laminar epidermal:dermal junction.     

Predicting and testing physical locations of genetically mapped loci on tomato pachytene chromosome 1

Predicting the chromosomal location of mapped markers has been difficult because linkage maps do not reveal differences in crossover frequencies along the physical structure of chromosomes. Here we combine a physical crossover map based on the distribution of recombination nodules (RNs) on Solanum lycopersicum (tomato) synaptonemal complex 1 with a molecular genetic linkage map from the interspecific hybrid S. lycopersicum x S. pennellii to predict the physical locations of 17 mapped loci on tomato pachytene chromosome 1. Except for one marker located in heterochromatin, the predicted locations agree well with the observed locations determined by fluorescence in situ hybridization. One advantage of this approach is that once the RN distribution has been determined, the chromosomal location of any mapped locus (current or future) can be predicted with a high level of confidence.