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.

Multiple human herpesvirus-8 infection

In Malawian patients with Kaposi sarcoma (KS) and their relatives, we investigated nucleotide-sequence variation in human herpesvirus-8 (HHV-8) subgenomic DNA, amplified from oral and blood samples by use of polymerase chain reaction. Twenty-four people had amplifiable HHV-8 DNA in >1 sample; 9 (38%) were seropositive for human immunodeficiency virus type 1, 21 (88%) were anti-HHV-8-seropositive, and 7 (29%) had KS. Sequence variation was sought in 3 loci of the HHV-8 genome: the internal repeat domain of open-reading frame (ORF) 73, the KS330 segment of ORF 26, and variable region 1 of ORF K1. Significant intraperson/intersample and intrasample sequence polymorphisms were observed in 14 people (60%). For 3 patients with KS, intraperson genotypic differences, arising from nucleotide sequence variations in ORFs 26 and K1, were found in blood and oral samples. For 2 other patients with KS and for 9 people without KS, intraperson genotypic and subgenotypic differences, originating predominantly from ORF K1, were found in oral samples; for the 2 patients with KS and for 4 individuals without KS, intrasample carriage of distinct ORF K1 sequences also were discernible. Our findings imply HHV-8 superinfection.

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.

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.

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.

Cytotoxic changes in hair cells secondary to pneumococcal middle-ear infection

To determine whether the bacterial toxins associated with otitis media could induce morphologic changes in the organ of Corti, we inoculated the middle-ear cavities of healthy guinea pigs with either Streptococcus pneumoniae or sterile saline and then examined the organ of Corti histologically at 1, 2, and 3 weeks postinoculation. We found that the outer hair cells (OHCs) in the infected ears underwent several changes that were dependent on both the length of time following inoculation and also the position of the OHCs in the cochlea. At 2 weeks postinoculation, 7.0 to 20% of the OHC nuclei from the infected animals became very swollen, with the most significant swelling occurring in the basal turn. At 3 weeks postinoculation, 2.5 to 3.5% of the OHCs were missing in the infected animals, with the most significant loss occurring in the basal and middle turns. These results suggest that bacterial otitis media can produce cytotoxic changes in the cochlea. These changes may be a clinically significant factor in the temporary and permanent sensorineural hearing loss that has been associated with bacterial otitis media.

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.

The effects of amplitude modulation on acoustic reflex decay

The temporal decay of the acoustic reflex provides the basis for an objective audiological test that differentiates cochlear from retrocochlear pathologies. The classic sign of a neural lesion is a rapid decay of the reflex under conditions of pure-tone stimulation for frequencies of 1,000 Hz and below. This restriction to lower frequencies is due to the fact that even normal ears show decay for higher-frequency signals. At present, it is unclear whether the acoustic reflex decay (ARD) seen in normal ears is related to frequency-specific channels or whether the critical variable is the timing information coded within the channels. This study examined ARD in subjects with normal hearing and middle ear function. The degree of ARD was measured for both modulated and unmodulated carrier frequencies of 500, 1,000, 2,000 and 4,000 Hz with amplitude modulation rates of 50-400 Hz. The dependent variable was the half-life of the decaying reflex (ARD 50%) over a 20-second stimulation interval. Significant ARD was present for high-frequency unmodulated carriers but not for low-frequency carriers. For all listeners, ARD was diminished for all modulated stimuli. The results of this study suggest that resistance to ARD is mediated by both the temporal aspects and frequency of a stimulus.

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.

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.

Preparation of casein using carbon dioxide

The effects of pressure, temperature, residence time, and mass of skim milk on some characteristics of casein, prepared by precipitation with high pressure CO2, were examined in a batch reactor. For a 500-g milk sample, precipitation occurred at pressures > 2760 kPa and temperatures > 32 degrees C. Residence time was not significant and was held at 5 min. Yields were maximum at 2750 to 5520 kPa and at 38 to 49 degrees C for a 500-g milk sample. The resulting whey had a pH of 6.0. The casein product had an acceptable appearance and had greater solids, ash, and Ca contents than commercial acid caseins. Particle size distribution studies showed that the mean particle size was sensitive to precipitation pressure and temperature and was similar to that of acid caseins produced under laboratory conditions. The HPLC studies of the casein and whey fractions showed that precipitation by CO2 did not result in fractionation of casein or whey proteins to their component proteins.

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.

Characteristics of a retrovirus associated with Jembrana disease in Bali cattle

A virus causing Jembrana disease in Bali cattle (Bos javanicus) was demonstrated to have characteristics of a retrovirus. Reverse transcriptase activity was detected in virus purified by sucrose gradient centrifugation. Electron microscopic examination of tissue from the affected cattle indicated that the virus matured by C-type budding through the plasma membrane and into intracytoplasmic vacuoles of cells in lymphoid tissue, with the formation of circular enveloped virus particles ranging in diameter from 96 to 124 nm with an eccentric nucleoid. Western immunoblotting using sera from recovered animals demonstrated virus proteins of M(r) 100K, 45K, 42K, 33K, 26K, 16K and 14K. The 26K protein of Jembrana disease virus cross-reacted in Western blots with the 26K capsid protein of bovine immunodeficiency virus (BIV). The apparent morphogenesis, protein structure and antigenic relationship with BIV suggested the virus was a lentivirus.

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.

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.

The structure and innervation of the saccopleural membrane of the domestic fowl, Gallus gallus: an ultrastructural and immunohistochemical study

Microscopic studies have shown the saccopleural membrane in the respiratory system of the domestic fowl to consist of a sheet of three dense layers of collagen fibres covered dorsally and ventrally by mainly simple squamous epithelium. On the ventral surface, which faces into the caudal thoracic air sac, there are occasional ridges of pseudostratified ciliated epithelium. Many nerve bundles are present throughout the membrane, the larger bundles of myelinated and unmyelinated axons being confined to the lamina propria under the dorsal epithelium (parietal pleura). In addition to axonal profiles with the ultrastructural appearance of cholinergic or adrenergic axons, peptidergic-type axons were identified. Immunofluorescence studies demonstrated VIP-, substance P-, somatostatin- and enkephalin-immunoreactive fibres in the membrane. Although it has been suggested that receptors may be present in this region of the respiratory system, none of the axons have features suggestive of sensory terminals, although many axonal profiles are closely associated with the epithelia where no obvious effector cells are present.

The spatio-temporal pattern of Wallerian degeneration in the rhesus monkey optic nerve

Three patterns of degeneration were distinguished in the Rhesus monkey optic nerve following eye enucleation. A traumatic zone, extending for 1 to 2 mm from the site of transection and characterized by a rapid infiltration of haematogenous macrophages, the rapid degeneration and removal of all neural elements and the formation of astrocytic scar tissue within 35 days. A conical zone, closely associated with the central retinal blood vessels, in which the pattern of degeneration was similar to the traumatic zone except that the onset was delayed and the removal of debris was slower. There was extensive vesiculation of myelin sheaths in these two zones which was indicative of haematogenous cell infiltration. The remainder of the nerve underwent classical Wallerian degeneration in which endogenous cells slowly phagocytosed the degenerating nerve fibres. These observations are considered relevant to the controversy concerning the identification of the macrophage involved in Wallerian degeneration; many studies have described the macrophage within the area of trauma rather than the macrophage involved at some distance from the site of trauma.

The abdominal air sac ostium of the domestic fowl: a sphincter regulated by neuro-epithelial cells?

A microscopic study of the ostium of the abdominal air sac of the domestic fowl has shown that the ostium has a sphincter-like ring of well innervated smooth muscle. Three types of neuro-epithelial cell characterised by their content of numerous large granular vesicles are found in the wall of the ostium. Type I cells are present within the submucosal nerve plexus and appear to be morphologically similar to SIF cells. Type II cells occur in the lamina propria, in clusters or cords, are often associated with fenestrated capillaries, and have synaptic contact with axonal terminals containing small agranular vesicles. The cells of Types I and II are not intra-epithelial and therefore differ from the cells which have been found elsewhere in the respiratory tract of the domestic fowl and other vertebrates. Type III cells are intra-epithelial, and some of those in the basal region of the epithelium are associated with axon terminals. Type III cells are similar in ultrastructure and location to neuro-epithelial cells found elsewhere in the major airways of the domestic fowl. They also resemble cells in neuro-epithelial bodies in amphibian, reptilian and mammalian lungs, although neuro-epithelial bodies have not been found in the lung of this species of bird. The morphology of the ostium suggests that it may have a sphincter-like function, possibly regulated by the neuro-epithelial cells. The presence of a mucociliary epithelium and defensive tissue in the lamina propria indicates that the ostium is the site of defence mechanisms.

Light and electron microscopical studies of the immunoperoxidase staining of multiple sclerosis plaques using antisera to a feline-derived agent and to galactocerebroside

Antibodies have been raised to two agents (CCA147 and MV631) that were isolated from central nervous tissue of cats. The cells co-cultivated with these agents are characterized by the presence of cytoplasmic inclusions consisting of 16-18 nm diameter tubular elements morphologically similar to inclusions seen in a demyelinating condition in cats and to inclusions described as 'curved linear profiles' in multiple sclerosis (MS) plaques. The peroxidase-labelled antibodies to CCA147 and MV631 stain these inclusions in MS plaques as well as small virus-like particles. The antisera do not stain normal white matter either in MS or non-MS brain tissue. The staining reaction of one agent is blocked by pretreatment with antisera to the other agent and also by pretreatment with MS sera but not by normal human sera. Peroxidase-labelled antibody to galactocerebroside stains normal myelin and myelin debris within MS plaques but does not stain the 'curved linear profiles' that are stained by the labelled antibodies to the feline-derived agents. The results show that the 'curved linear profiles' described in MS plaques are not myelin degradation products, but are comparable to the nucleocapsids of morbilliviruses. In addition, the small virus-like particles are morphologically similar to morbillivirus virions. The results are discussed with particular emphasis on the features of the morbilliviruses, canine distemper and measles viruses.

Primary demyelination in the central nervous system of cats

Primary demyelinating lesions have been observed in the central nervous system of 16 (approximately 7%) of a total of 235 clinically normal cats. The size of the lesions varied from small perivascular lesions in white matter to a large lesion occupying the diameter of an optic nerve. Intracytoplasmic inclusions consisting of tubular structures were common to all lesions examined by electron microscopy. The features of these feline lesions are briefly compared with those seen in multiple sclerosis.

Detection and prevalence of serotypes of feline syncytial spumaviruses

Three serotypes of feline syncytial virus (FSV) were detected by neutralisation tests: 906, a serotype of low prevalence and 702 and 951 which were serotypes of higher prevalence, between which a minor one-way antigenic difference was detected. Serum antibody in naturally-infected cats in some cases neutralised 951 but not 702 or 906 which suggested that 951 could be considered as a major distinct serotype. An increase in prevalence of antibody to FSV in cats over a 5 year period from 1977-1981 was detected by neutralisation, agar gel immunodiffusion, and fluorescent antibody techniques. Over the 5 year period the prevalence of antibody to the 951 serotype increased and the overall increase in prevalence of antibody to FSV during this period appeared to relate to dissemination of the 951 serotype.

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.

The effect of age on biochemical and morphological changes in the semitendinosus muscle of cattle with generalized glycogenosis type II

Progressive changes in acid alpha-glucosidase activity, glycogen content and light microscopical and ultrastructural features in skeletal muscle of calves affected by generalized glycogenosis type II were assessed in biopsies from semitendinosus muscle of nine affected, twenty-six carrier and fifteen normal calves taken at varying times between birth and 17 months of age. Affected animals could be identified by using the PAS technique on paraffin and epon embedded material or by electron microscopy. However, estimation of acid alpha-glucosidase activity was required for precise diagnosis of generalized glycogenosis type II or to distinguish between normal and carrier animals. The glycogen content of the semitendinosus muscle of affected animals was approximately three times that in non-affected animals and although storage of glycogen reached a plateau soon after birth, the muscle fibre damage seen in very young calves increased with age. Morphological evidence of glycogen accumulation, both within the cytoplasm and within membrane bound structures, was present at birth. In some animals evidence of muscle fibre regeneration and damage was seen in the same sections.