Survival Dynamics of Aphanomyces cochlioides Oospores Exposed to Heat Stress.

ABSTRACT To determine how exposure to heat effects their survival, oospores of Aphanomyces cochlioides isolate C22 were exposed in water to 35, 40, 45, or 50 degrees C for prescribed times and then examined for viability. The Weibull model was modified to represent the effects of temperature on survival of oospores. The final fitted model gave lethal doses for 50% of the oospores of 251, 49.8, 9.8, and 1.9 h at 35, 40, 45, and 50 degrees C, respectively. To determine if alternating high and low temperatures resulted in (i) recovery from heat damage during low temperature periods, (ii) increased susceptibility to heat damage, or (iii) if effects of heat damage were cumulative, oospores were examined after each of four 24-h cycles at 45 degrees C for 4 h and 21 degrees C for 20 h. Survival of oospores exposed to alternating high and low temperatures fit the cumulative effects model. Significant variability in heat tolerance among five isolates was observed (P< 0.001) but model parameters successfully accommodated this variability (R(2) = 0.96, P < 0.001). This research shows that under wet conditions, there are predictable patterns to mortality for A. cochlioides oospores exposed to continuous or fluctuating high temperatures.

Tracking familial transmission of Kaposi's sarcoma-associated herpesvirus using restriction fragment length polymorphism analysis of latent nuclear antigen.

Intra-familial transmission of Kaposi's sarcoma associated herpesvirus (KSHV) is likely to occur in geographical regions where KSHV infection is highly endemic. Transmission has been studied previously indirectly using serological techniques, however direct documentation of specific transmission routes has yet to be reported. The internal repeat domain (IRD) of the KSHV opening reading frame (ORF) 73 was shown previously to exhibit restriction-fragment length polymorphism (RFLP). Analysis of such polymorphism was undertaken using nested ORF 73 IRD PCR products derived from the blood and mouth rinse samples of individuals in Malawian family groups. The resulting RFLP patterns were unique to an individual and could be compared between family members. In three of eight families studied, identical RFLP patterns were recovered from family members; in the remaining five families, dissimilar RFLP patterns were revealed. Results from RFLP analysis were compared to sequencing data recovered from family members for the first variable region of the hypervariable KSHV ORF K1. Patterns of intra- and extra-familial transmission inferred from ORF K1 sequencing data were corroborated mainly using ORF 73 IRD RFLP analysis.

Recovery of viral agents from the central nervous system of cats.

Isolation of viruses from the central nervous system (CNS) of cats was attempted using an explant culture technique and subsequent co-cultivation with Crandell feline kidney (CRFK) or Vero cells. Feline syncytia-forming virus was isolated from the CNS of 11 of 16 cats where the initial co-cultivation was with CRFK cells. Feline panleucopaenia virus was isolated from the CNS of 2 adult cats. Co-cultured cells from the CNS of 3 cats contained eosinophilic cytoplasmic and intranuclear inclusions. The cytoplasmic inclusions consisted of tubular structures, 16-18 nm in diameter and up to 500 nm in length, which were similar in morphology to paramyxovirus nucleocapsids. The 3 co-cultured cells with cytoplasmic and intranuclear inclusions showed haemadsorption of guinea pig erythrocytes. The possible identity of these structures, and their association with a previously described primary focal demyelinating lesion in the CNS of cats, is discussed.

Morphology and innervation of the buccal glands of the Southern Hemisphere lamprey, Geotria australis.

The buccal glands of adults of the Southern Hemisphere lamprey Geotria australis consist of a pair of small, bean-shaped, hollow sacs, embedded within the basilaris muscle in the region below the eyes and to either side of the piston cartilage. Each gland, which is lined by a simple columnar epithelium and surrounded by an incomplete layer of skeletal muscle, discharges its contents into the oral cavity via a long, narrow duct. In downstream migrating young adults, the epithelial cells are low columnar, intermediate in electron density, and contain dark-staining inclusions and numerous lipid-like droplets. After saltwater acclimation, the epithelial cells become taller and the numbers of dark-staining inclusions increase whereas those of lipid-like droplets decline. By the end of the marine phase, the epithelium is more folded and now also contains dark and light cells. The ultrastructure of the epithelium shows the characteristics of both apocrine and merocrine secretion. Although intra-epithelial nerve endings were not observed, axons and occasional neurons are present in the lamina propria. Since the skeletal muscle capsule is also well innervated and contains neurons, a local feed-back mechanism may regulate the release of buccal gland fluid by monitoring the luminal pressure. Contractions of the skeletal muscle capsule and movements of the basilaris muscle during feeding would presumably assist the movement of secretion along the duct. The secretion possesses anticoagulating and haemolytic properties.

Endoscopic staple-assisted esophagodiverticulostomy: an excellent treatment of choice for Zenker's diverticulum.

OBJECTIVES: The objectives of the present study are to review the technique of endoscopic staple-assisted esophagodiverticulostomy (ESED) for the treatment of Zenker's diverticulum and to describe our experience and modifications with ESED and the advantages of ESED over previous treatments of Zenker's diverticulum. STUDY DESIGN: Retrospective review of 74 cases of ESED performed for the treatment of Zenker's diverticulum. METHODS: Patient's records were retrospectively reviewed and tabulated for age, sex, size of diverticulum, symptoms, duration of symptoms, operative time, length of postoperative hospital stay, oral intake, complications, and relief of symptoms. RESULTS: The senior author (R.L.S) previously reported results in 36 cases of ESED performed in 34 patients with Zenker's diverticulum. We have performed an additional 38 cases of ESED in 37 patients between March 1997 and August 1999. The rate of success of ESED was similar between the two series The average perioperative time, time until oral intake, and length of postoperative hospital stay decreased in the second series. Overall, there were no mortalities and few complications with ESED. Compared with other forms of treatment of Zenker's diverticulum, such as Dohlman's procedure, diverticulectomy, and diverticulopexy, ESED has a similar rate of success, decreased perioperative time, decreased convalescence, and decreased mortality and complications. CONCLUSIONS: Cost-effectiveness, safety, and efficacy of ESED offer new advantages over previously used treatments for Zenker's diverticulum. These results continue to support the use of ESED as the initial treatment of choice for patients with Zenker's diverticulum.

Intracranial injection of drugs: comparison of diffusion of 6-OHDA and guanethidine.

Marked differences in extent of diffusion have been shown with the fluorescence histochemical method between guanethidine and 6-OHDA(64 mug in 2 mul) when injected acutely or chronically into the lateral hypothalamus, the substantia nigra or the amygdala of the rat brain. Cannulation damage up to 1 mm in diameter and attributed to the implantation of cannulae and placebo injection was observed. A further area of generalized damage occurred following the injection of drugs and was far greater for 6-OHDA (2 mm) than for guanethidien (0.3 mm). Guanethidine, but not 6-OHDA, caused specific damage to catecholamine-containing nerurons up to a distance of at least 3 mm and more from the cannula tip. These striking differences between the effects of intracranial injection of 6-OHDA and guanethidine are discussed in terms of the uptake and degradation of the two drugs and the anatomical features of the injection site; they are not explicable in terms of experimental conditions such as concentration, volume of injection, molecular weight or lipid solubility. The different patterns of damage would not easily be distinguished by biochemical analyses and the catecholamine specificity of 6-OHDA in studies of the central nervous system must be seriously questioned. Vascularization of chronically implanted cannula tracks and the presence of anatomical diffusion barriers are also discussed in relation to the diffusion of drugs injected intracranially.

Chronic conductive hearing loss in adults: effects on the auditory brainstem response and masking-level difference.

OBJECTIVE: To determine whether chronic conductive hearing loss in adults results in changes in the auditory brainstem response (ABR) similar to those observed in children with histories of otitis media with effusion. DESIGN: Test of effect of unilateral conductive hearing loss on adult ABR using age-matched control group and subjects as their own controls. SUBJECTS: Twelve adults with a history of unilateral conductive ear disease. An age-matched control group of 21 adults was also tested. METHODS: The ABR, an electrophysiologic test of auditory brainstem functioning, was used to evaluate possible brainstem abnormalities in the impaired listeners. In addition, the masking-level difference, a behavioral test of binaural auditory processing in the brainstem, was used. RESULTS: When comparing the patients' diseased ears with their healthy ears, significant delays were seen for wave V as well as for the I-V and III-V interwave intervals. For comparison with the control population, significant prolongations were again seen for wave V and for the III-V interwave intervals. In addition, reduced masking-level differences and significant correlations between the masking-level differences and the ABRs, independent of hearing threshold, were noted. CONCLUSIONS: The results suggest that chronic conductive impairment in adults leads to changes in the ABR similar to those observed in children with histories of otitis media with effusion. As such, these changes do not appear to be related to a critical period of development.

ACT3: a high-speed, high-precision electrical impedance tomograph.

This paper presents the design, implementation, and performance of Rensselaer's third-generation Adaptive Current Tomograph, ACT3. This system uses 32 current sources and 32 phase-sensitive voltmeters to make a 32-electrode system that is capable of applying arbitrary spatial patterns of current. The instrumentation provides 16 b precision on both the current values and the real and reactive voltage readings and can collect the data for a single image in 133 ms. Additionally, the instrument is able to automatically calibrate its voltmeters and current sources and adjust the current source output impedance under computer control. The major system components are discussed in detail and performance results are given. Images obtained using stationary agar targets and a moving pendulum in a phantom as well as in vivo resistivity profiles showing human respiration are shown.

Inactivation of microorganisms with microwaves at reduced temperatures.

We developed a pilot-plant nonthermal flow process using microwave energy to inactivate microorganisms. The process consists of multiple passes through the microwave generator. Each passed material goes to a receiving tank for subsequent passes. The flow rate was 0.96 to 1.26 kg/min and the dwell time per pass was 1.1 to 1.5 min. Five passes were used. The microwave energy is instantaneously and simultaneously applied to the system, and thermal energy is removed by a cooling tube within the process line in the microwave generator. The cooling tube maintains the temperature below 40 degrees C. There was significant reduction in microorganisms in water, 10% glucose solution, and apple juice, and in yeast in beer. There was a slight decrease in microorganisms in tomato juice, pineapple juice, apple cider, and beer; and no effect in skim milk.

Effect of stenting after laryngotracheal reconstruction in a subglottic stenosis model.

OBJECTIVES: This study addresses the impact of stenting on early wound healing after laryngotracheal reconstruction (LTR) in a rabbit model with established subglottic stenosis. METHODS: Subglottic stenosis was created in 42 New Zealand white rabbits through a transoral, endoscopic technique. Three weeks later, endoscopy and axial CT were performed to document and grade the degree of stenosis. Subsequently, LTR was performed in all animals, with half of the animals receiving an intraluminal stent. Four rabbits from each group were euthanized on postoperative days 6, 9, 14, 21, and 28. Measurements of graft vascularization were obtained with a computerized image measurement program, and a comparison was made regarding the rate of vascularization. RESULTS: There was a statistically significant increase in the rate of vascularization in the stented group (mean 75% +/- 5% vs 56% +/- 3% at day 14; P < 0. 05). However, clinical and radiographic comparisons of the stented and nonstented specimens revealed a trend toward increased mucosal edema and granulation tissue in the stented group at later time intervals (days 21 and 28). CONCLUSION: This analysis suggests that stenting does not inhibit graft vascularization in the early postoperative period after LTR; however, complications were seen in the stented group at longer time intervals.

Multiple sclerosis: is the domestic cat involved?

Recent evidence suggests a possible viral aetiology of multiple sclerosis (MS). The present hypothesis proposes a relationship between MS and a demyelinating condition in the central nervous system of cats from which a paramyxovirus has been isolated. The theory attempts to relate the distribution and incidence of MS with the keeping of cats as household pets. The incidence of MS is explained on the basis of a human susceptibility factor, perhaps the histocompatibility antigens and the onset, remissions and relapse of MS are considered to be related to stressful situations which trigger a persistent virus.

Subglottic stenosis: correlation between computed tomography and bronchoscopy.

The evaluation of subglottic stenosis has been limited by the lack of standardized methods for determining the cross-sectional area and length of the stenotic segment. A rabbit model was used to prospectively evaluate the correlation between computed tomography (CT) and bronchoscopy in the evaluation of this disease. Subglottic stenosis was produced in 39 New Zealand White rabbits by a transoral endoscopic technique. The animals were evaluated 3 weeks later with spiral CT, rigid bronchoscopy, and open laryngotracheal exploration. Spiral CT was performed with the location, degree, and length of subglottic stenosis being determined by a blinded observer. Each animal then underwent rigid bronchoscopy and open laryngotracheal exploration for determination of the same measurements. Data were analyzed to determine the correlation between the radiographic and surgical techniques in evaluating the airway stenosis. With regard to the degree of stenosis, 94% of the rabbits were determined to have CT and bronchoscopic measurements that were within 15% (Pearson correlation .94, p < .05). With regard to the length of stenosis, 94% of animals had a measurement on CT that was within 2 mm of that observed upon open exploration (Pearson correlation .81, p < .05). The CT evaluation of subglottic stenosis correlated well with the currently used method of visual inspection at bronchoscopy in evaluating tracheal stenosis in this animal model. These data suggest that CT could serve as a useful adjunct in the evaluation of tracheal stenosis, especially when serial examinations are required.

Hepatic damage in sheep fed annual ryegrass, Lolium rigidum, parasitised by Anguina agrostis and Corynebacterium rathayi.

Annual ryegrass (Lolium rigidum) parasitised by Anguina agrostis and Corynebacterium rathayi causes neurological signs and brain lesions thought to be associated with a vasoconstrictor effect of the toxic grass. In three separate experiments of six to 112 days duration parasitised ryegrass was fed to 21 adult sheep. The concentrations of many blood constituents were examined, liver biopsies taken, necropsies performed and tissues other than brain examined by light and electron microscopy. The invariable finding was liver damage indicated by increased plasma concentrations of liver specific enzymes and bilirubin. There was diffuse vacuolation of hepatocytes due to gross distension of cisternae of rough endoplasmic reticulum, as well as necrosis of individual hepatocytes, fatty change, biliary hyperplasia and hepatocytic regeneration. The changes were not typical of experimental hepatic ischaemia and may have been due to a cytopathic effect of toxic annual ryegrass.

Stress fractures of the anterior tibial diaphysis.

Stress fracture of the anterior tibial diaphysis is rare and occurs mostly in leaping athletes. Thirty-six of these fractures in 35 patients have been reported in the literature. These are combined with 15 similar fractures in our experience to provide combined data on 51 anterior tibial stress fractures. Comparison of the various treatments utilized disclosed that there is a high risk of complete fracture if affected patients are allowed full activity, and that treatment by rest alone allowed only 40% to return to full activity even after symptomatic improvement. The treatment recommended for these patients is excision of the fissure, transverse drilling at the fissure site, and cancellous bone grafting of the defect. In those patients who suffer a complete fracture, open reduction and internal fixation is superior to closed treatment.