Detection of pathogenic Yersinia enterocolitica by using congo red-magnesium oxalate agar medium.

A Congo red-magnesium oxalate agar medium was developed to detect expression of virulence-associated calcium dependency and Congo red absorption in Yersinia enterocolitica. Of the 157 pathogenic serotypes tested, 119 (75.8%) were positive; 98% of nonpathogenic serotypes and strains of three other Yersinia species were negative.     

Studies on the mechanism of interferon action: Characterization of polysome-associated cellular RNAs modified by interferon

A recent publication indicated that certain polysome-associated RNA species are altered in interferon-treated cells. The present data show that these RNA species are poly(A)-containing mRNAs, RNAs without a poly(A)-rich region and tRNAs. In addition, we show that in polyacrylamide gels in aqueous medium as well as in nonaqueous medium (formamide) the mRNAs from interferon-treated cells migrate more slowly than do control cell mRNAs, suggesting that the interferon mRNAs are slightly larger than normal. Transfer RNAs from interferon-treated cells, on the other hand, move more slowly than control tRNAs in aqueous medium, but not in formamide, suggesting that the difference in mobility in tRNAs is associated with factors other than size.     

Cephalometric analyses and flow-volume loops in obstructive sleep apnea patients

Fifteen patients with obstructive sleep apnea syndrome (OSAS) and 10 controls were studied. Polygraphic monitoring during sleep confirmed the presence or absence of OSAS. Ten OSAS patients and five controls had cephalometric analysis and 12 OSAS patients and five controls had a flow-volume loop study during wakefulness. Seven OSAS patients were submitted to both analyses. Flow-volume loops were unable to detect extrathoracic airway obstruction in six out of 12 OSAS patients. One control was found with positive results. Six out of seven subjects with positive flow-volume loops were overweight (greater than or equal to 30% ideal weight). Cephalograms were very useful in demonstrating mandibular deficiencies in OSAS patients. The length of the soft palate and the position of the hyoid bone, together with the measurement of the posterior airway space, are criteria of great interest in OSAS patients. Cephalometric analysis is recommended in all OSAS patients scheduled for surgical procedure. None of these tests, however, whether alone or in combination, is capable of identifying all cases of OSAS.     

B cell precursors are decreased in senescent BALB/c mice, but retain normal mitotic activity in vivo and in vitro

The numbers of phenotypic (sIg- Ly5[220]+) and functional B cell precursors were significantly reduced in the bone marrow of senescent (22-24 months old) BALB/c mice when compared to their young (2-4 months old) cohorts. Little alteration in the numbers of B cell precursors occurred during the first 12 months of life in this strain. In contrast, an accelerated loss of B cell precursors between 15 and 18 months of age was observed. In particular, the levels of small Ly5(220)+ B cell precursors were decreased with advanced age, although a decline in numbers of large sIg- Ly5(220)+ B cell precursors was also evident. The percentages of large sIg- Ly5(220)+ B cell precursors in (S + G2/M) stages of cell cycle were similar (e.g., 60-80%) in aged and young BALB/c mice. Importantly, Ly5(220)+ pre-B cells from both young and aged BALB/c mice, either present in vivo or derived from Ly5(220)- cells in vitro, were capable of proliferation in response to rIL-7. These observations suggest that the aging process results in a progressive decline in the numbers of pre-B cells; however, this apparently is not due to failure of B lineage precursor cells to respond to growth mediators either in vivo or in vitro.     

Amelioration of established Sendai viral pneumonia in the nude mouse using a monoclonal antibody to the virus fusion protein.

The pathological effect of parainfluenza type I (Sendai virus) is known to be a bronchopneumonia, which becomes a chronic pneumonia in the immunodeficient athymic (nude) mouse. The severity of this established chronic pneumonia can be dramatically altered by providing the nude mouse with humoral monoclonal antibodies which are neutralizing, and are directed against the fusion protein, of the virus. The alveolitis, which is a significant part of the pathology, is suppressed due to a reduction (greater than 90%) in the number of virus-infected alveolar macrophages present in the alveoli. This clearly identifies the infected alveolar macrophage as the primary effector cell in the pathogenesis of alveolitis caused by parainfluenza virus type I. The implications of using virus-neutralizing monoclonal antibodies, which have little immunomodulatory toxicity, in the treatment of viral pneumonias are discussed.     

The effects of UV-B irradiation on the corneal endothelium

Rabbit eyes, in vivo and in vitro, were exposed to UV-B irradiation at 300 nm, from a mercury arc lamp with an 11 nm bandpass filter. Radiant exposure ranged from 0.1 J/cm2 to 0.5 J/cm2. In vivo, swelling of the cornea resulted over a 12 to 40 hr period, the extent and duration being directly related to exposure. Recovery of normal thickness was complete within four days. Corneas removed at 18 hr after exposure recovered normal thickness during a five hour perfusion period, except for those most heavily exposed. When removed at 42 hr post exposure all corneas thinned to almost normal thickness. SEM showed the endothelial cells of exposed eyes to have either exaggerated villi on the surface and a disorganized mosaic or, after higher exposures, to be devoid of villi and have loose, flap like cell borders and large "blebs." After exposure of isolated corneas mounted for perfusion, swelling again ensued and similar changes were observed in the appearance of the cells, except that "blebs" were not found. No significant changes were observed in the metabolic components ATP, ascorbate and glutathione, nor was there any indication of lipid peroxidation. At higher in vivo exposures, the aqueous humor did show a decrease in ascorbate concentration and an increase in protein content, which probably result from a breakdown of the blood-aqueous barrier. UV-B irradiation may cause or promote changes in the endothelium associated with aging, but the one time radiant exposures of the magnitude used in this study, appear to have no severe or permanently toxic effects.     

Preliminary observations on the application of the multiple inocula (replicator) method for carbon substrate utilization studies of Alcaligenes faecalis.

The use of the replicator technique in evaluating carbon source utilization by 55 cultures of Alcaligenes faecalis was examined. Six of the 20 substrates tested were utilized by the bacterial cultures. In this study, the reproducibility of the technique was 100%.     

An evaluation of three methods for determining colloid osmotic pressure

Plasma colloid osmotic pressure (COP) is an important determinant in edema formation. Three methods for assessing the COP were evaluated. Direct measurement of COP using the 4420 Wescor Colloid Osmometer was compared to the estimation of COP from both serum total protein and total serum solids (TSS) determinations. Blood samples from twenty adult patients (mean age = 64 years) undergoing cardiopulmonary bypass surgery were collected for COP assessment. Sample collection was performed prior to heparinization/hemodilution, during hypothermic bypass and at the conclusion of bypass following protamine administration. The results obtained from each method were analyzed by a two-way analysis of variance. The Bonferroni technique was used for comparison of sample means when the difference was significant (p less than 0.05). Correlations were reported by linear regression analysis. A statistically significant difference (p less than 0.01) was found between the three methods. A regression equation for the estimation of COP from total serum solids is offered: COP = (3.02 * TSS) + 0.65. Prospective clinical testing between the direct COP measurement and the estimation of COP from TSS using the equation (n = 38) revealed a significant correlation (R2 = .932) and no significant difference between the two (p greater than 0.05).     

Comparison of gaseous microemboli counts in arterial, simultaneous and venous heat exchange with a hollow fiber membrane oxygenator

Potential sources of gaseous microemboli during cardiopulmonary bypass are varied. However, it is known that membrane oxygenators generate fewer gaseous microemboli than bubble oxygenators and that bubblers cannot utilize arterial heat exchange without generating significant gaseous microemboli during rewarming. A membrane oxygenator utilizing simultaneous gas and heat exchange raises the concern that concurrent gas and heat exchange would result in a higher production of gaseous microemboli compared to conventional venous heat exchange devices. This in vitro study compared venous, simultaneous, arterial and control (venous) heat exchanger gaseous microemboli counts during rewarming. No significant difference was found between the four heat exchangers when comparing inlet and outlet gaseous microemboli counts. This in vitro study suggests that there is no difference in gaseous microemboli generation when varying the position of the heat exchanger in the extracorporeal circuit incorporating a microporous membrane oxygenator.