Comparison of computed tomography and myelography to a reference standard of computed tomographic myelography for evaluation of dogs with intervertebral disc disease

OBJECTIVE

To compare the sensitivity of computed tomography (CT) and myelography to a reference standard of CT myelography for determining localization of Type I intervertebral disc extrusions in dogs.

STUDY DESIGN

Prospective blinded comparative study.

ANIMALS

Dogs with acute onset myelopathy because of suspected disc extrusions (n = 30).

METHODS

Dogs had CT, myelography, and CT myelography to diagnose disc extrusions. Sensitivity of CT and myelography was compared to CT myelography for lateral, longitudinal, and combined localization. Confidence in the assessment of each imaging study was scored by 3 reviewers.

RESULTS

Sensitivity of CT for lateral, longitudinal, and combined localization was 94%, 91%, and 81%, respectively, and was 64%, 74%, and 53%, respectively for myelography. Sensitivity of all 3 categories of localization was significantly different between modalities (P < .0001, P = .0031, P < .0001). Significant differences in the sensitivity of lateral and combined localization were found between confidence scores for myelography (P < .0001, P < .0001). Significant differences in the sensitivity of lateral, longitudinal, and combined localization were found between confidence scores for CT (P = .011, P = .013, P = .027). Poor sensitivity was obtained for both modalities except when imaging studies were assigned the highest confidence score.

CONCLUSIONS

CT is a more sensitive imaging technique than myelography for localizing disc extrusions when compared to a reference standard of CT myelography. Both modalities yielded high sensitivity with the highest confidence score and poor sensitivity for all other confidence scores.

Determining the Oleic/linoleic Acid Ratio in a Single Peanut Seed: a Comparison of Two Methods

Peanut varieties with high oleic/linoleic acid ratios have become preferred by the peanut industry due to their increased shelf life and improved health benefits. Many peanut breeding programs are trying to incorporate the high oleic trait into new and improved varieties and are in need of diagnostic tools to track its inheritance early in development and at the single seed level. Traditionally, gas chromatography has been used to accurately determine the properties of peanut oil. Recently a method was developed to carry out this analysis by capillary elecrophoresis providing researchers with an alternative analytical platform. In this study, the use of capillary electrophoresis and gas chromatography for analysis of oleic/linoleic acid ratios are compared. Oil was extracted from approximately 0.10 g of peanut seed tissue taken from the distal end, leaving the embryonic end of the seed intact for subsequent germination. Over 100 samples inclusive of runner, Spanish and Virginia market types were processed. Oil extracts were analyzed for oleic/linoleic acid ratio using (1) capillary electrophoresis (CE) and (2) gas chromatography (GC). Results showed that the two methods are 100% in agreement in determining whether a peanut seed is “high-oleic” or “normal oleic” in oil content. Furthermore, the two methods are highly correlated (r  =  0.96; p &lt; 0.0001) with respect to determining the exact oleic/linoleic acid ratio from each sample. Results from this study validate the use of CE as a diagnostic tool for breeding programs to identify individual high oleic peanut seed for further testing and development.

The unfolded protein response is triggered by a plant viral movement protein

Infection with Potato virus X (PVX) in Nicotiana benthamiana plants leads to increased transcript levels of several stress-related host genes, including basic-region leucine zipper 60 (bZIP60), SKP1, ER luminal binding protein (BiP), protein disulfide isomerase (PDI), calreticulin (CRT), and calmodulin (CAM). bZIP60 is a key transcription factor that responds to endoplasmic reticulum (ER) stress and induces the expression of ER-resident chaperones (BiP, PDI, CRT, and CAM). SKP1 is a component of SCF (for SKP1-Cullin-F box protein) ubiquitin ligase complexes that target proteins for proteasomal degradation. Expression of PVX TGBp3 from a heterologous vector induces the same set of genes in N. benthamiana and Arabidopsis (Arabidopsis thaliana) leaves. Virus-induced gene silencing was employed to knock down the expression of bZIP60 and SKP1, and the number of infection foci on inoculated leaves was reduced and systemic PVX accumulation was altered. Silencing bZIP60 led to the suppression of BiP and SKP1 transcript levels, suggesting that bZIP60 might be an upstream signal transducer. Overexpression of TGBp3 led to localized necrosis, but coexpression of TGBp3 with BiP abrogated necrosis, demonstrating that the unfolded protein response alleviates ER stress-related cell death. Steady-state levels of PVX replicase and TGBp2 (which reside in the ER) proteins were unaltered by the presence of TGBp3, suggesting that TGBp3 does not contribute to their turnover. Taken together, PVX TGBp3-induced ER stress leads to up-regulation of bZIP60 and unfolded protein response-related gene expression, which may be important to regulate cellular cytotoxicity that could otherwise lead to cell death if viral proteins reach high levels in the ER.

Cold air-induced late-phase bronchoconstriction in horses

REASON FOR PERFORMING STUDY

Inspired air is warmed to body temperature and fully humidified by the upper airway mucosa under normal resting conditions. This conditioning process may not be completed by the upper airways during conditions of increased minute ventilation or when the inspired air is unusually cold, resulting in cooling and desiccation of lower respiratory surfaces. Excess heat and water loss from intrapulmonary airways is believed to be the provocative stimulus for exercise-induced bronchoconstriction (occurring immediately after exercise) and associated late phase airway obstruction (occurring a few hours after exercise).

HYPOTHESIS

Exercise while breathing cold air results in airway obstruction in horses.

METHODS

Eight healthy horses performed a 15 min submaximal exercise challenge in a random crossover design. Independent variable was inspired air temperature during the challenge (25 or -5 degrees C). The dependent variables were total respiratory impedance, resistance, and reactance at 5, 24 and 48 h post exercise challenge, expressed as a percentage of the prechallenge baseline.

RESULTS

No significant effect of inspired air temperature was found on any respiratory mechanical parameter 5 h after exercise challenge. However, cold inspired air was associated with higher respiratory impedance and resistance 48 h after the exercise challenges.

CONCLUSIONS

These findings support the hypothesis that submaximal exercise while breathing subfreezing air can adversely affect respiratory mechanical properties in normal horses. However, the timecourse for development of abnormal respiratory mechanical properties is longer than that reported in other mammals.

CLINICAL RELEVANCE

Exercise in cold weather may be a common cause of lower airway disease in horses.

Comparison of flat-panel digital to conventional film-screen radiography in detection of experimentally created lesions of the equine third metacarpal bone

Radiographic diagnosis of equine bone disease using digital radiography is prevalent in veterinary practice. However, the diagnostic quality of digital vs. conventional radiography has not been compared systematically. We hypothesized that digital radiography would be superior to film-screen radiography for detection of subtle lesions of the equine third metacarpal bone. Twenty-four third metacarpal bones were collected from horses euthanized for reasons other than orthopedic disease. Bones were dissected free of soft tissue and computed tomography was performed to ensure that no osseous abnormalities were present. Subtle osseous lesions were produced in the dorsal cortex of the third metacarpal bones, and the bones were radiographed in a soft tissue phantom using indirect digital and conventional radiography at standard exposures. Digital radiographs were printed onto film. Three Diplomates of the American College of Veterinary Radiology evaluated the radiographs for the presence or absence of a lesion. Receiver operator characteristic curves were constructed, and the area under these curves were compared to assess the ability of the digital and film-screen radiographic systems to detect lesions. The area under the ROC curves for film-screen and digital radiography were 0.87 and 0.90, respectively (P = 0.59). We concluded that the digital radiographic system was comparable to the film-screen system for detection of subtle lesions of the equine third metacarpal bone.

Hypogammaglobulinemia in racing Alaskan sled dogs

BACKGROUND

Serum immunoglobulin dynamics have not been studied in racing sled dogs, despite hypoglobulinemia having been reported during racing events.

HYPOTHESIS/OBJECTIVES

Hypoglobulinemia in racing sled dogs is associated with decreases in serum IgA, IgE, IgG, and IgM concentrations during prolonged exercise.

ANIMALS

One hundred and fifty-seven Alaskan sled dogs that successfully completed a 1,000 mile race.

METHODS

Serum was obtained from 118 sled dogs within 1 month before the race and within 12 hours after completing the race. Serum also was obtained after 4 months of rest from 51 dogs that successfully completed the race, including 12 previously sampled dogs. Serum total protein ([TP]), albumin, and globulin ([Gl]) were measured, and serum IgA, IgE, IgG, and IgM were quantified by ELISA.

RESULTS

The proportion of dogs with [Gl] < or = 2.2 g/dL was significantly greater immediately after racing (38 of 118 dogs, 32.2%) than before racing (21 of 118 dogs, 17.8%, P = .005). Four months after racing, [Gl] was < or = 2.2 g/dL in 23.5% (12 of 51) of dogs. [IgG] was significantly lower before (8.21 +/- 4.95 mg/mL) and immediately after (7.97 +/- 5.62) racing compared with 4 months after racing (18.88 +/- 5.76). Serum [IgM] and [IgE] were higher and [IgA] was lower before racing compared with immediately after racing.

CONCLUSIONS AND CLINICAL IMPORTANCE

Sled dogs participating in long-distance racing have substantial decreases in [IgG] in addition to decreases in [IgM] and [IgE]. The pronounced hypogammaglobulinemia observed in a large proportion of racing sled dogs might predispose them to infectious disease.

Analysis of potato virus X replicase and TGBp3 subcellular locations

Potato virus X (PVX) infection leads to certain cytopathological modifications of the host endomembrane system. The subcellular location of the PVX replicase was previously unknown while the PVX TGBp3 protein was previously reported to reside in the ER. Using PVX infectious clones expressing the green fluorescent protein reporter, and antisera detecting the PVX replicase and host membrane markers, we examined the subcellular distribution of the PVX replicase in relation to the TGBp3. Confocal and electron microscopic observations revealed that the replicase localizes in membrane bound structures that derive from the ER. A subset of TGBp3 resides in the ER at the same location as the replicase. Sucrose gradient fractionation showed that the PVX replicase and TGBp3 proteins co-fractionate with ER marker proteins. This localization represents a region where both proteins may be synthesized and/or function. There is no evidence to indicate that either PVX protein moves into the Golgi apparatus. Cerulenin, a drug that inhibits de novo membrane synthesis, also inhibited PVX replication. These combined data indicate that PVX replication relies on ER-derived membrane recruitment and membrane proliferation.

Type I IFN response to Papiine herpesvirus 2 (Herpesvirus papio 2; HVP2) determines neuropathogenicity in mice

Isolates of baboon alpha-herpesvirus Papiine herpesvirus 2 (HVP2) exhibit one of two distinct phenotypes in mice: extremely neurovirulent or apathogenic. Previous studies implicated the type I interferon (IFN) response as being a major factor in controlling infection by apathogenic isolates. To further investigate the possibility that the host IFN-beta response underlies the pathogenicity of the two HVP2 subtypes, the susceptibility of mice lacking the IFN-beta receptor (IFNAR(-/-)) to infection was examined. Apathogenic isolates of HVP2 (HVP2ap) replicated in IFNAR(-/-) primary mouse dermal fibroblast (PMDF) cultures as well as neurovirulent (HVP2nv) isolates. IFNAR(-/-) mice were also susceptible to lethal infection by HVP2ap isolates. Unlike Balb/c or parental 129 mice, LD(50) and ID(50) values for HVP2ap were the same in IFNAR(-/-) mice indicating that in these mice infection always progressed to death. HVP2ap replicated in the skin at the site of inoculation and invaded dorsal root ganglia as efficiently as HVP2nv in IFNAR(-/-) mice. Since the virion host shutoff (vhs) protein encoded by the UL41 gene of herpes simplex virus has been implicated in circumventing the host IFN-beta response and the phenotype of UL41 deletion mutants of HSV is very similar to that of HVP2ap isolates, the UL41 gene was deleted from HVP2nv (Delta 41) and replaced with the UL41 ORF from HVP2ap (Delta 41C). Like the parental HVP2nv virus, the Delta 41C recombinant replicated efficiently in Balb/c PMDFs and did not induce a strong IFN-beta response. The neuropathogenicity of the Delta 41C recombinant was also the same as the parental HVP2nv virus in Balb/c mice, indicating that the vhs protein does not underlie the different neuropathogenic phenotype of HVP2ap and HVP2nv. In contrast, the Delta 41 deletion virus induced a strong IFN-beta response but was still able to undergo multiple rounds of replication in PMDF cultures, albeit at a slower pace than the parental HVP2nv. This was reflected in vivo as the Delta 41 mutant had an LD(50) equivalent to that of the parental HVP2nv virus although the time to death was longer. These results indicate that while the vhs protein is involved in preventing and/or suppressing an IFN-beta response, it is not responsible for the ability of HVP2nv to overcome IFN-beta induced resistance of uninfected cells and does not underlie the divergent pathogenicity of the two HVP2 subtypes in mice.

Evaluation of topical epidural morphine for postoperative analgesia following hemilaminectomy in dogs

A randomized prospective study was conducted in dogs undergoing hemi-laminectomy procedures for Hansen type I disk protrusion to compare postoperative analgesia achieved with topical spinal application of morphine versus saline. An absorbable gelatin sponge was placed in the defect next to the dura and soaked with either preservative-free morphine (0.1 mg/kg) or saline (0.1 ml/kg) just before wound closure. For 48 hours after surgery, dogs were monitored for pain using visual analog and numeric descriptive scales and given rescue analgesia according to study guidelines. A Kaplan-Meier survival analysis revealed that dogs in the morphine group had a longer (13.3 +/- 3.6 hours) duration of postoperative analgesia than those in the control saline group (5.3 +/- 1.8 hours), and dogs in the morphine group also required fewer doses of additional pain medication. Preservative-free morphine administered topically via an absorbable gelatin sponge appears to be a promising method to alleviate postoperative pain in dogs undergoing hemilaminectomy procedures.

Phloem unloading of potato virus X movement proteins is regulated by virus and host factors

To determine the requirements for viral proteins exiting the phloem, transgenic plants expressing green fluorescent protein (GFP) fused to the Potato virus X (PVX) triple gene block (TGB)p1 and coat protein (CP) genes were prepared. The fused genes were transgenically expressed from the companion cell (CC)-specific Commelina yellow mottle virus (CoYMV) promoter. Transgenic plants were selected for evidence of GFP fluorescence in CC and sieve elements (SE) and proteins were determined to be phloem mobile based on their ability to translocate across a graft union into nontransgenic scions. Petioles and leaves were analyzed to determine the requirements for phloem unloading of the fluorescence proteins. In petioles, fluorescence spread throughout the photosynthetic vascular cells (chlorenchyma) but did not move into the cortex, indicating a specific barrier to proteins exiting the vasculature. In leaves, fluorescence was mainly restricted to the veins. However, in virus-infected plants or leaves treated with a cocktail of proteasome inhibitors, fluorescence spread into leaf mesophyll cells. These data indicate that PVX contributes factors which enable specific unloading of cognate viral proteins and that proteolysis may play a role in limiting proteins in the phloem and surrounding chlorenchyma.

Protein expression in the baculovirus system

Insect cell-recombinant baculovirus co-cultures offer a protein production system that complements microbial systems by providing recombinant proteins in soluble form and with most post-translational modifications. Moreover, the large size of the viral genome enables cloning of large segments of DNA and consequent expression of complex protein aggregates. This unit describes methods associated with the large-scale production of recombinant proteins in the baculovirus expression system. A method for large-scale production of viral stocks is described and methods for titration of virus are provided (a plaque assay and an end-point assay). Once viral stocks have been prepared and titered, a protocol for testing the virus in small-scale cultures is provided to determine the kinetics of expression, which allows evaluation of various cell culture and infection conditions aimed at developing optimal levels of protein production (e.g., comparisons of different host cell lines, media, and environmental parameters). Support protocols provide instructions for preparing culture samples for protein analysis by SDS-PAGE and discuss analytical methods for monitoring nutrient levels in cell culture fluids. Once optimal process parameters are identified, protocols describe production of the target protein on a large scale in fermentors using either regular batch production in bioreactors or a fed-batch procedure of production in perfusion cultures. Techniques for harvesting cultures from bioreactors are also provided.

Selection of Escherichia coli expression systems

This unit lists the most useful expression strains of E. coli for fermentation processes. Standard procedures are provided for several expression systems, namely, temperature induction via the p(L) promoter and chemical induction via the trp promoter, lac or tac promoters, and the T7 promoter. These protocols require that the gene encoding the protein of interest has been identified and cloned into an appropriate expression vector using standard molecular biology techniques. Transformation of a suitable host strain (e.g., by electroporation) is also described and is a prerequisite. Protocols for the analysis of plasmid stability and subsequent storage are provided. Support protocols describe how to prepare samples for electrophoresis, how to analyze the solubility of the expressed proteins, and how to make samples of periplasmic extracts and extracellular media (using TCA precipitation). Many of the support protocols are small-scale analysis procedures that are used to guide subsequent purification strategies and determine the suitability of the expression system for further development and scale-up.

Protein expression in the baculovirus system

Insect cell-recombinant baculovirus co-cultures offer a protein production system that complements microbial systems by providing recombinant proteins in soluble form and with most post-translational modifications. Moreover, the large size of the viral genome enables cloning of large segments of DNA and consequent expression of complex protein aggregates. This unit describes methods associated with the large-scale production of recombinant proteins in the baculovirus expression system. A method for large-scale production of viral stocks is described and methods for titration of virus are provided (a plaque assay and an end-point assay). Once viral stocks have been prepared and titered, a protocol for testing the virus in small-scale cultures is provided to determine the kinetics of expression, which allows evaluation of various cell culture and infection conditions aimed at developing optimal levels of protein production (e.g., comparisons of different host cell lines, media, and environmental parameters). Support protocols provide instructions for preparing culture samples for protein analysis by SDS-PAGE and discuss analytical methods for monitoring nutrient levels in cell culture fluids. Once optimal process parameters are identified, protocols describe production of the target protein on a large scale in fermentors using either regular batch production in bioreactors or a fed-batch procedure of production in perfusion cultures. Techniques for harvesting cultures from bioreactors are also provided.

Beet necrotic yellow vein virus accumulates inside resting spores and zoosporangia of its vector Polymyxa betae BNYVV infects P. betae

BACKGROUND

Plasmodiophorids and chytrids are zoosporic parasites of algae and land plant and are distributed worldwide. There are 35 species belonging to the order Plasmodiophorales and three species, Polymyxa betae, P. graminis, and Spongospora subterranea, are plant viral vectors. Plasmodiophorid transmitted viruses are positive strand RNA viruses belonging to five genera. Beet necrotic yellow vein virus (BNYVV) and its vector, P. betae, are the causal agents for rhizomania.

RESULTS

Evidence of BNYVV replication and movement proteins associating with P. betae resting spores was initially obtained using immunofluorescence labeling and well characterized antisera to each of the BNYVV proteins. Root cross sections were further examined using immunogold labeling and electron microscopy. BNYVV proteins translated from each of the four genomic and subgenomic RNAs accumulate inside P. betae resting spores and zoospores. Statistical analysis was used to determine if immunolabelling detected viral proteins in specific subcellular domains and at a level greater than in control samples.

CONCLUSION

Virus-like particles were detected in zoosporangia. Association of BNYVV replication and movement proteins with sporangial and sporogenic stages of P. betae suggest that BNYVV resides inside its vector during more than one life cycle stage. These data suggest that P. betae might be a host as well as a vector for BNYVV.

Effect of training and recovery on airway inflammation in an animal model of ‘ski asthma’

Repeated strenuous exercise while breathing cold air is believed to induce chronic airway inflammation and hyperreactivity, a condition referred to in humans as ‘ski asthma’. However, the time course of development and resolution of ski asthma is unknown. We have previously shown that multi-day aerobic exercise induces airway inflammation and hyperreactivity in racing sled dogs. In the present study, a similar group of subjects was examined at multiple times during training to test the hypothesis that ski asthma spontaneously resolves during seasonal detraining, but is re-induced during training in the cold weather. At the beginning of training, bronchoalveolar lavage fluid (BALF) from detrained elite sled dogs (n = 16) had higher concentrations of lymphocytes (median 53.63 vs. 8.30 cells μl−1) and neutrophils (median 23.03 vs. 1.10 cells μl−1) compared with normal laboratory dogs (n = 5). However, there was no significant effect of training on BALF nucleated cell concentrations from exercised sled dogs (n = 11) compared with sedentary sled dogs (n = 8). In contrast to our hypothesis, our data support the contention that cold weather exercise-induced airway inflammation can persist through seasonal detraining, but that routine training does not cause significant worsening of the condition.

Comparison of anesthetic and cardiorespiratory effects of tiletamine-zolazepam-butorphanol and tiletamine-zolazepam-butorphanol-medetomidine in dogs

This study compared anesthetic and cardiorespiratory effects of tiletamine-zolazepam-butorphanol (TT), tiletamine-zolazepam-butorphanol-medetomidine (TTD), and tiletamine-zolazepam-butorphanol-medetomidine with atipamezole reversal 1 hour after TTD administration in dogs. All dogs received glycopyrrolate. All drug combinations effectively induced anesthesia within 5 minutes after IM injection. Duration of analgesia was 40 to 60 minutes. Recovery was smooth, but the overall quality of recovery was poorer in the TT group. Hypoxia occurred with some dogs in the TTD group at 5 minutes. TTD provided better analgesia with longer duration and better recovery quality compared with TT. Reversal of TTD with atipamezole was not effective in shortening recovery time.

A comparison of anesthetic and cardiorespiratory effects of tiletamine-zolazepam-butorphanol and tiletamine-zolazepam-butorphanol- medetomidine in cats

Using a randomized crossover design, this study compared the anesthetic and cardiorespiratory effects of three intramuscular anesthetic combinations in seven 2-year-old cats: tiletamine-zolazepam (8 mg/kg) and butorphanol (0.2 mg/kg) (TT); tiletamine-zolazepam (3 mg/kg), butorphanol (0.15 mg/kg), and medetomidine (15 microg/kg) (TTD); or the TTD protocol plus atipamezole (75 microg/kg IM) given 20 minutes later to reverse medetomidine. Analgesia was assessed using algometry and needle pricking. All three combinations effectively induced anesthesia suitable for orotracheal intubation within 5 minutes after injection. Hemoglobin oxygen saturation was lower than 90% at least once in all three groups between 5 and 15 minutes after drug administration. Blood pressure and heart and respiratory rates were within normal ranges. Both TT and TTD appeared to be effective injectable anesthetic combinations. TTD provided significantly better analgesia with a longer duration than did TT. Atipamezole administration shortened the duration of analgesia and decreased blood pressure but did not shorten total recovery time.

Temporal relationship between gastrointestinal protein loss, gastric ulceration or erosion, and strenuous exercise in racing Alaskan sled dogs

BACKGROUND

Alterations in the appearance and function of gastrointestinal mucosa are common after strenuous exercise. However, the duration of exercise required to alter the gastrointestinal mucosa has not been reported.

HYPOTHESIS

We used 42 sled dogs to test the hypothesis that the magnitude of exercise-induced gastrointestinal mucosal dysfunction is related to exercise duration.

ANIMALS

Six dogs served as conditioned controls, and the remaining dogs were randomly chosen for examination after 1-5 consecutive days of running at 100 miles/d.

METHODS

Gastroduodenoscopy and measurement of gastric permeability were performed 24 hours after cessation of exercise. Intestinal protein loss (represented by fecal alpha-1 protease inhibitor concentration) was measured within 6 hours of cessation of exercise. Twelve of the 42 dogs were examined again after 5 months of detraining to determine the effect of training on gastrointestinal mucosal function.

RESULTS

Exercise increased gastric permeability (P = .04) and endoscopic severity of gastric lesions (P < .0001), but neither variable was significantly affected by distance traveled. Acute exercise had no effect on intestinal protein loss. Untrained dogs had significantly lower fecal alpha-1 protease inhibitor concentrations compared with trained, unexercised dogs. Training had no effect on gastric permeability to sucrose or the endoscopic appearance of the stomach.

CONCLUSIONS AND CLINICAL IMPORTANCE

These data suggest that relatively modest exercise is required to increase intestinal protein loss, but more substantial exercise is required to cause alterations in the proximal gastrointestinal tract. However, none of these alterations appear to progress with increasing exercise duration.

Effect of training and rest on respiratory mechanical properties in racing sled dogs

INTRODUCTION

Racing Alaskan sled dogs develop exercise-induced airway inflammation, similar to that reported for elite human athletes participating in cold-weather sports. These human athletes also have airway hyperresponsiveness, but airway function in sled dogs has not been measured.

PURPOSE

To compare respiratory mechanical properties in trained, rested Alaskan sled dogs with typical laboratory hounds, and to determine whether subsequent training alters respiratory mechanical properties.

METHODS

Nineteen healthy adult Alaskan sled dogs were compared with five healthy adult mixed-breed laboratory hounds. All dogs were rested for at least 4 months before examination. Respiratory mechanical properties were measured while the dogs were anesthetized and ventilated with a piston ventilator. The mean respiratory resistance and compliance measurements for 20 consecutive breaths were used as baseline values immediately before measurement of respiratory reactivity. Respiratory reactivity was the mean of 20 consecutive breaths immediately after the administration of aerosol histamine, expressed as the percentage change in prehistamine measurements. After the initial examinations, the sled dogs were divided into exercised and controls. Exercised dogs were trained for competitive endurance racing. Both groups were examined after 2 and 4 months of training.

RESULTS

Alaskan sled dogs had greater respiratory compliance reactivity to histamine (77.47 +/- 8.58% baseline) compared with laboratory dogs (87.60 +/- 9.22% baseline). There was no effect of training on respiratory mechanical properties detected in racing sled dogs.

CONCLUSIONS

Racing Alaskan sled dogs have airway dysfunction similar to "ski asthma" that persists despite having 4 months of rest. These findings suggest that repeated exercise in cold conditions can lead to airway disease that does not readily resolve with cessation of exercise.

Maternally and naturally acquired antibodies to Mannheimia haemolytica and Pasteurella multocida in beef calves

The dynamics and duration of maternally derived antibodies as well as the onset of acquired immunity against Mannheimia haemolytica and Pasteurella multocida in range-pastured beef calves were investigated. Two groups of unvaccinated cattle were used in this study. Serum antibody responses were measured by enzyme-linked immunoassay for antibodies of the IgG1, IgG2 and IgM isotypes binding M. haemolytica whole cells (WC) or leukotoxin (LKT) and P. multocida outer membrane proteins (OMPs). Comparisons of mean antibody responses to M. haemolytica LKT and WC and P. multocida OMPs were made within each group. Maternally derived antibodies against M. haemolytica and P. multocida reached lowest levels at 30-90 days after birth. Calves began production of antibodies against M. haemolytica and P. multocida between 60 and 90 days of age in both groups. Based on the results of this study, in beef herds vaccinated against M. haemolytica and/or P. multocida, it may be best to vaccinate calves around 3 months of age. In contrast, beef calves from unvaccinated herds might benefit from vaccination at 4 months of age.

Effect of soil properties on lead bioavailability and toxicity to earthworms

Soil properties are important factors modifying metal bioavailability to ecological receptors. Twenty-one soils with a wide range of soil properties (USA; http://soils.usda.gov/technical/classification/taxonomy/) were amended with a single concentration of Pb (2,000 mg/kg) to determine the effects of soil properties on Pb bioavailability and toxicity to earthworms. Earthworm mortality ranged from 0 to 100% acute mortality following exposure to the same total concentration of Pb (2,000 mg/kg) in amended field soils. Internal Pb concentrations in earthworms ranged from 28.7 to 782 mg/kg, with a mean of 271 mg/kg. Path analysis was used to partition correlations in an attempt to discern the relative contribution of each soil property. Results of path analysis indicated that pH was the most important soil property affecting earthworm mortality (p < 0.01) and internal Pb (p < 0.05). Soil pH was related inversely to mortality and internal Pb, soil solution Pb, and Pb bioavailability. The most important soil property modifying reproduction was amorphous iron and aluminum oxides (FEAL). Because FEAL is rich in pH-dependent cation-exchange sites, several soil properties, including pH, FEAL, and cation-exchange capacity, have a causal effect on Pb adsorption and soluble Pb. Path analysis is useful for assessing contaminated soils with a wide range of soil properties and can assist in ecological risk assessment and remediation decisions for contaminated sites. Soil properties are important factors modifying metal bioavailability and toxicity and should be considered during the ecological risk assessment of metals in contaminated soils.

Neuropathogenesis of herpesvirus papio 2 in mice parallels infection with Cercopithecine herpesvirus 1 (B virus) in humans

Cercopithecine herpesvirus 1 (monkey B virus; BV) produces extremely severe and usually fatal infections when transmitted from macaque monkeys to humans. Cercopithecine herpesvirus 16 (herpesvirus papio 2; HVP2) is very closely related to BV, yet cases of human HVP2 infection are unknown. However, following intramuscular inoculation of mice, HVP2 rapidly invades the peripheral nervous system and ascends the central nervous system (CNS) resulting in death, very much like human BV infections. In this study, the neurovirulence of HVP2 in mice was further evaluated as a potential model system for human BV infections. HVP2 was consistently neurovirulent when administered by epidermal scarification, intracranial inoculation and an eye splash. Quantitative real-time PCR, histopathology and immunohistochemistry were used to follow the temporal spread of virus following skin scarification and to compare the pathogenesis of neurovirulent and apathogenic isolates of HVP2. Apathogenic isolates were found to be capable of reaching the CNS but were extremely inefficient at replicating within the CNS. It is concluded that neurovirulent strains of HVP2 exhibit a pathogenesis in mice that parallels that observed in human BV infections and that this model system may prove useful in dissecting the viral determinants underlying the extreme severity of zoonotic BV infections.

The potato virus X TGBp2 movement protein associates with endoplasmic reticulum-derived vesicles during virus infection

The green fluorescent protein (GFP) gene was fused to the potato virus X (PVX) TGBp2 gene, inserted into either the PVX infectious clone or pRTL2 plasmids, and used to study protein subcellular targeting. In protoplasts and plants inoculated with PVX-GFP:TGBp2 or transfected with pRTL2-GFP:TGBp2, fluorescence was mainly in vesicles and the endoplasmic reticulum (ER). During late stages of virus infection, fluorescence became increasingly cytosolic and nuclear. Protoplasts transfected with PVX-GFP:TGBp2 or pRTL2-GFP:TGBp2 were treated with cycloheximide and the decline of GFP fluorescence was greater in virus-infected protoplasts than in pRTL2-GFP:TGBp2-transfected protoplasts. Thus, protein instability is enhanced in virus-infected protoplasts, which may account for the cytosolic and nuclear fluorescence during late stages of infection. Immunogold labeling and electron microscopy were used to further characterize the GFP:TGBp2-induced vesicles. Label was associated with the ER and vesicles, but not the Golgi apparatus. The TGBp2-induced vesicles appeared to be ER derived. For comparison, plasmids expressing GFP fused to TGBp3 were transfected to protoplasts, bombarded to tobacco leaves, and studied in transgenic leaves. The GFP:TGBp3 proteins were associated mainly with the ER and did not cause obvious changes in the endomembrane architecture, suggesting that the vesicles reported in GFP:TGBp2 studies were induced by the PVX TGBp2 protein. In double-labeling studies using confocal microscopy, fluorescence was associated with actin filaments, but not with Golgi vesicles. We propose a model in which reorganization of the ER and increased protein degradation is linked to plasmodesmata gating.

Mortality of life stages of cowpea weevil (Coleoptera: Bruchidae) exposed to low pressure at different temperatures

Previous studies have shown that low pressure creates a low oxygen controlled atmosphere that can kill stored-product insects. The current study was conducted to determine the mortality of life stages of the cowpea weevil, Callosbruchus maculatus (F.) (Coleoptera: Bruchidae), exposed to different low pressures and temperatures for various exposure periods. The adults were the most susceptible life stage to low pressure; 99% mortality was achieved within 0.8 h at 32.5 mmHg, 30 degrees C. The pupae were the most tolerant life stage to low pressure, requiring exposure periods between 28.98 and 153.20 h at temperatures of 20-35 degrees C to achieve 99% mortality. Mortality increased with exposure time and also with increasing temperature in all life stages. Early stage eggs (3 h old) and late stage eggs (48 h old) experienced higher mortality (values for LT99 of 42.331 and 46.652 h, respectively) compared with intermediate aged eggs (24 h old; LT99 of 74.735 h) under the same conditions of low pressure and temperature. Dried beans, including cowpea, Vigna unguiculata (Walp.), are currently protected with fumigants. Application of low pressure as a pest management tool represents a potential nonchemical alternative to fumigants such as methyl bromide and phosphine for controlling the cowpea weevil and related bruchids.

Economic evaluation of the effects of planting date and application rate of imidacloprid for management of cereal aphids and barley yellow dwarf in winter wheat

The effects of planting date and application rate of imidacloprid for control of Schizaphis graminum Rondani, Rhopalosiphum padi L. (Homoptera: Aphididae), and barley yellow dwarf virus (BYDV) in hard red winter wheat were studied. The first experiment was conducted from 1997 to 1999 at two locations and consisted of three planting dates and four rates of imidacloprid-treated seed. The second experiment was conducted from 2001 to 2002 in Stillwater, OK, and consisted of two varieties of hard red winter wheat seed and four rates of imidacloprid. Aphid densities, occurrence of BYDV, yield components, and final grain yield were measured, and yield differences were used to estimate the economic return obtained from using imidacloprid. In the first study, aphid populations responded to insecticide rate in the early and middle plantings, but the response was reduced in the late planting. Yields increased as insecticide rate increased but did not always result in a positive economic return. In the second study, imidacloprid seed treatments reduced aphid numbers and BYD occurrence, protected yield, and resulted in a positive economic return. The presence of aphids and BYDV lowered yield by reducing fertile head density, total kernel weight, and test weight. Whereas the application of imidacloprid seed treatments often provided positive yield protection, it did not did not consistently provide a positive economic return. A positive economic return was consistently obtained if the cereal aphid was carrying and transmitting BYDV and was more likely to occur if wheat was treated with a low rate if imidacloprid and planted in a "dual purpose" planting date window.

Generation and analysis of mice with a targeted disruption of the arylamine N-acetyltransferase type 2 gene

Arylamine N-acetyltransferases (NATs) are polymorphic xenobiotic metabolising enzymes, linked to cancer susceptibility in a variety of tissues. In humans and in mice there are multiple NAT isoforms. To identify whether the different isoforms represent inbuilt redundancy or whether they have unique roles, we have generated mice with a null allele of Nat2 by gene targeting. This mouse line conclusively demonstrates that the different isoforms have distinct functions with no compensatory expression in the Nat2 null animals of the other isoforms. In addition, we have used the transgenic line to show the pattern of Nat2 expression during development. Although Nat2 is not essential for embryonic development, it has a widespread tissue distribution from at least embryonic day 9.5. This mouse line now paves the way for the teratological role of Nat2 to be tested.

Mortality of eggs of stored-product insects held under vacuum: effects of pressure, temperature, and exposure time

Low pressure applied to a commodity creates a low-oxygen atmosphere that can be effective to control stored-product insects. Previous work determined that eggs of several species of stored-product insects were among the most tolerant life stages to low pressure. The current study was conducted to determine the mortality of eggs in response to various pressures, temperatures, and exposure times. An initial experiment determined that the sensitivity of eggs to vacuum varied with their age. Eggs of Plodia interpunctella (Hübner) were most sensitive to low pressure when they were 3 or 48 h old, whereas those of Rhyzopertha dominica (F.) were most sensitive at 12 and 120 h of age. In subsequent experiments, eggs of Cadra cautella (Walker), P. interpunctella, R. dominica, and Tribolium castaneum (Herbst) were exposed to pressures of 50, 75, 100, 200, and 300 mmHg in glass chambers at 5, 15, 22.5, 30, and 37.5 degrees C for times ranging from 12 to 168 h. Time-mortality data were subjected to probit analyses and lethal dose ratios were computed to determine differences in lethal time values among species across the 25 low pressure-temperature combinations for each species. In all four species the mortality of eggs increased with increasing exposure time and temperature. Low temperatures and high pressures were the least effective conditions for killing eggs, compared with high temperatures combined with low pressures in all species investigated. These results provide important guidelines for developing treatment schedules for disinfestation of commodities on a commercial scale.

Evidence that the 37 kDa protein of Soil-borne wheat mosaic virus is a virus movement protein

Experiments were conducted to determine if the 37 kDa protein (37K) of Soil-borne wheat mosaic virus (SBWMV) is a virus movement protein. First, evidence was obtained that indicated that 37K has the ability to move from cell to cell, similar to other virus movement proteins (MPs). Plasmids containing the GFP gene fused to the SBWMV 37K, the coat protein (CP) or the CP readthrough domain (RT) ORFs were delivered by biolistic bombardment to wheat and tobacco leaves. In wheat leaves, cell-to-cell movement of GFP-37K was observed, while GFP, GFP-CP and GFP-RT accumulated primarily in single cells. All fusion proteins accumulated in single cells in tobacco leaves. Thus, cell-to-cell movement is a specific property of 37K that occurs in SBWMV host plants. Subcellular accumulation of 37K was studied using SBWMV-infected and 37K-expressing transgenic wheat. In infected and transgenic wheat leaves, 37K accumulated in the cell wall, similar to other virus MPs, and in aggregates in the cytoplasm. Phylogenetic studies were conducted to compare the furovirus 37K proteins with members of the 30K superfamily of virus MPs. Amino acid sequences of the furovirus 37K proteins were aligned with the MPs from 43 representative viruses. The furovirus 37K proteins were found to reside in a clade that also contained the dianthovirus MPs. Combined, these data suggest that SBWMV 37K is probably a virus MP.

The potato virus X TGBp2 protein association with the endoplasmic reticulum plays a role in but is not sufficient for viral cell-to-cell movement

Potato virus X (PVX) TGBp1, TGBp2, TGBp3, and coat protein are required for virus cell-to-cell movement. Plasmids expressing GFP fused to TGBp2 were bombarded to leaf epidermal cells and GFP:TGBp2 moved cell to cell in Nicotiana benthamiana leaves but not in Nicotiana tabacum leaves. GFP:TGBp2 movement was observed in TGBp1-transgenic N. tabacum, indicating that TGBp2 requires TGBp1 to promote its movement in N. tabacum. In this study, GFP:TGBp2 was detected in a polygonal pattern that resembles the endoplasmic reticulum (ER) network. Amino acid sequence analysis revealed TGBp2 has two putative transmembrane domains. Two mutations separately introduced into the coding sequences encompassing the putative transmembrane domains within the GFP:TGBp2 plasmids and PVX genome, disrupted membrane binding of GFP:TGBp2, inhibited GFP:TGBp2 movement in N. benthamiana and TGBp1-expressing N. tabacum, and inhibited PVX movement. A third mutation, lying outside the transmembrane domains, had no effect on GFP:TGBp2 ER association or movement in N. benthamiana but inhibited GFP:TGBp2 movement in TGBp1-expressing N. tabacum and PVX movement in either Nicotiana species. Thus, ER association of TGBp2 may be required but not be sufficient for virus movement. TGBp2 likely provides an activity for PVX movement beyond ER association.

The Potato virus X TGBp3 protein associates with the ER network for virus cell-to-cell movement

Potato virus X (PVX) TGBp3 is required for virus cell-to-cell movement. Cell-to-cell movement of TGBp3 was studied using biolistic bombardment of plasmids expressing GFP:TGBp3. TGBp3 moves between cells in Nicotiana benthamiana, but requires TGBp1 to move in N. tabacum leaves. In tobacco leaves GFP:TGBp3 accumulated in a pattern resembling the endoplasmic reticulum (ER). To determine if the ER network is important for GFP:TGBp3 and for PVX cell-to-cell movement, a single mutation inhibiting membrane binding of TGBp3 was introduced into GFP:TGBp3 and into PVX. This mutation disrupted movement of GFP:TGBp3 and PVX. Brefeldin A, which disrupts the ER network, also inhibited GFP:TGBp3 movement in both Nicotiana species. Two deletion mutations, that do not affect membrane binding, hindered GFP:TGBp3 and PVX cell-to-cell movement. Plasmids expressing GFP:TGBp2 and GFP:TGBp3 were bombarded to several other PVX hosts and neither protein moved between adjacent cells. In most hosts, TGBp2 or TGBp3 cannot move cell-to-cell.

Ecotoxicological risks associated with land treatment of petrochemical wastes. I. Residual soil contamination and bioaccumulation by cotton rats (Sigmodon hispidus)

Petrochemical waste contains both organic and inorganic contaminants that can pollute soil and may pose significant ecological risks to wildlife. Petrochemical waste typically is disposed of in land treatment units, which are widespread throughout Oklahoma and the United States. Few studies have been conducted evaluating possible toxicity risks to terrestrial organisms residing on these units. In this study, the extent of soil contamination with fluoride (F), metals, and organic hydrocarbons, the bioaccumulation of F and metals in cotton rats (Sigmodon hispidus), the relationship between contaminants in soil and in tissues of cotton rats, and the level of potentially toxic polycyclic aromatic hydrocarbons (PAHs) in soil were determined on land treatment units. Over a 2-yr period, cotton rats and soils were collected and analyzed from 5 land treatment and matched reference units. The number of land treatment units with soil metal contamination (in parentheses) included: Cr, Cu, Pb (5). Al, As, Ni, Sr, Zn (4). Ba (3). and Cd, V (2). The number of land treatment units with soil PAH contamination (in parentheses) were naphthalene, phenanthrene, benzo[g,h,i]perylene (3). acenaphthene, anthracene, pyrene, benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[a]pyrene, indeno[1,2,3-c,d]pyrene, dibenz[a,h]anthracene (2). and acenaphthylene, fluorene, fluoranthene, benzo[k]fluoranthene (1). Total PAH and total petroleum hydrocarbons (TPH) were elevated at all five land treatment units. Mean sums of benzo[a]pyrene (BaP) equivalents (BaPequiv ) were not affected on

Modeling the acute- and late-phase responses to peripheral airway cooling and desiccation

Acute bronchoconstriction after isocapnic hyperpnea can be produced in most asthmatic individuals. However, the existence of a late-phase response is less certain. We used a canine model of isocapnic hyperpnea to test the hypothesis that this discrepancy is due to differences in the challenge threshold for the responses. Acute-phase and late-phase bronchoconstriction was measured in nine dogs after peripheral airway exposure to unconditioned air. Additionally, bronchoalveolar lavage fluid (BALF) was obtained during the late-phase response. The acute-phase response was a polynomial function with a decreasing slope at higher challenges, whereas the late-phase response suggested that a minimum threshold of challenge severity was needed to produce late-phase bronchoconstriction. BALF leukocyte and eicosanoid concentrations had linear relationships with challenge severity. Our data support the hypothesis that acute- and late-phase posthyperpnea responses have different dose-response relationships, a fact that may explain the frequent lack of a late-phase response. However, our data suggest that mild inflammation can be induced with relatively lower challenge severity.

The COOH terminus of arylamine N-acetyltransferase from Salmonella typhimurium controls enzymic activity

Arylamine N-acetyltransferases (NATs) are a homologous family of enzymes, which acetylate arylamines, arylhydroxylamines, and arylhydrazines by acetyl transfer from acetyl-coenzyme A (Ac-CoA) and are found in many organisms. NAT was first identified as the enzyme responsible for the inactivation of the anti-tubercular drug isoniazid in humans. The three-dimensional structure of NAT from Salmonella typhimurium has been resolved and shown to have three distinct domains and an active site catalytic triad composed of "Cys(69)-His(107)-Asp(122)," which is typical of hydrolytic enzymes such as the cysteine proteases. The crystal unit cell consists of a dimer of tetramers, with the C terminus of individual monomers juxtaposed. To investigate the function of the first two domains of full-length NAT from S. typhimurium and to investigate the role of the C terminus of NAT, truncation mutants were made with either the C-terminal undecapeptide or the entire third domain (85 amino acids) missing. Unlike the full-length NAT protein (281 amino acids), the truncation mutants of NAT from S. typhimurium are toxic when overexpressed intracellularly in Escherichia coli. Full-length NAT hydrolyses Ac-CoA but only in the presence of an arylamine substrate. Both truncation mutants, however, hydrolyze Ac-CoA even in the absence of arylamine substrate, illustrating that the C-terminal undecapeptide controls hydrolysis of Ac-CoA by NAT from S. typhimurium.

Evidence towards the role of arylamine N-acetyltransferase in Mycobacterium smegmatis and development of a specific antiserum against the homologous enzyme of Mycobacterium tuberculosis

Arylamine N-acetyltransferase (NAT) in humans inactivates the anti-tubercular drug isoniazid (INH). Homologues of human NAT are present in Mycobacterium tuberculosis and Mycobacterium smegmatis, where they can acetylate, and hence inactivate, INH. The in vivo role of mycobacterial NAT is not known but heterologous expression of the M. tuberculosis gene increases the INH resistance. The 0.85 kb nat gene is part of a gene cluster in M. smegmatis. The gene is transcribed as a large, 7.5 kb mRNA as demonstrated by Northern analysis. A nat knockout strain of M. smegmatis was generated by targeted disruption. The new strain was confirmed to be devoid of NAT activity. The growth of the knockout strain is considerably delayed compared with the wild-type, due to an extended lag phase. The knockout mutant has an increased sensitivity to INH as would be predicted. The NATs from M. smegmatis and M. tuberculosis have a high degree of homology, except in the region of the C terminus. A specific polyclonal antiserum raised against recombinant NAT protein from M. tuberculosis is described that recognizes a stretch of about twenty residues within the C terminus of M. tuberculosis NAT. This highly specific antiserum will enable comparison of nat expression between isolates of M. tuberculosis.

Eubacterial arylamine N-acetyltransferases - identification and comparison of 18 members of the protein family with conserved active site cysteine, histidine and aspartate residues

Arylamine N-acetyltransferases (NATs) are enzymes involved in the detoxification of a range of arylamine and hydrazine-based xenobiotics. NATs have been implicated in the endogenous metabolism of p-aminobenzoyl glutamate in eukaryotes, although very little is known about the distribution and function of NAT in the prokaryotic kingdom. Using DNA library screening techniques and the analysis of data from whole-genome sequencing projects, we have identified 18 nat-like sequences from the Proteobacteria and Firmicutes. Recently, the three-dimensional structure of NAT derived from the bacterium Salmonella typhimurium (PDB accession code 1E2T) was resolved and revealed an active site catalytic triad composed of Cys(69)-His(107)-Asp(122). These residues have been shown to be conserved in all prokaryotic and eukaryotic NAT homologues together with three highly conserved regions which are found proximal to the active site triad. The characterization of prokaryotic NATs and NAT-like enzymes is reported. It is also predicted that prokaryotic NATs, based on gene cluster composition and distribution amongst genomes, participate in the metabolism of xenobiotics derived from decomposition of organic materials.

Chromosome mapping of the genes for murine arylamine N-acetyltransferases (NATs), enzymes involved in the metabolism of carcinogens: identification of a novel upstream noncoding exon for murine Nat2

Arylamine N-acetyltransferases (NATs) catalyse acetylation reactions which can result in either detoxification or activation of arylamine carcinogens. The human NAT loci (NAT1, NAT2, and a pseudogene, NATP) have been mapped to human chromosome 8p22, a region frequently deleted in tumours. There are three functional genes in mice (Nat1, Nat2, and Nat3) encoding for three NAT isoenzymes. Different alleles at the Nat2 locus are responsible for the acetylation polymorphism identified in different mouse strains. We show that Nat3 is close to Nat1 and Nat2, by screening of a P1 artificial chromosome (PAC) library and provide cytogenetic evidence for co-localisation of the three genes in chromosome region 8 B3.1-B3.3. The Nat region of mouse and human is homologous. We also provide sequence information and a restriction map in the vicinity of Nat1 and Nat2 and describe a noncoding exon located 6 kb upstream of the Nat2 coding region.

An update on genetic, structural and functional studies of arylamine N-acetyltransferases in eucaryotes and procaryotes

Arylamine N:-acetyltransferase (NAT) was first identified as the inactivator of the anti-tubercular drug isoniazid. The enzyme was shown to catalyse the transfer of an acetyl group from acetyl-CoA to the terminal nitrogen of the hydrazine drug. The rate of inactivation of isoniazid was polymorphically distributed in the population and was one of the first examples of pharmacogenetic variation. NAT was identified recently in Mycobacterium tuberculosis and is a candidate for modulating the response to isoniazid. Genome sequences have revealed many homologous members of this unique family of enzymes. The first three-dimensional structure of a member of the NAT family identifies a catalytic triad consisting of aspartate, histidine and cysteine proposed to form the activation mechanism. So far, all procaryotic NATs resemble the human enzyme which acetylates isoniazid (NAT2). Human NAT2 is characteristic of drug-metabolizing enzymes: it is found in liver and intestine. In humans and other mammals, there are up to three different isoenzymes. If only one isoenzyme is present, it is like human NAT1. Human NAT1 and its murine equivalent specifically acetylate the folate catabolite p-aminobenzoylglutamate. NAT1 and its murine homologue each have a ubiquitous tissue distribution and are expressed early in development at the blastocyst stage. During murine embryonic development, NAT is expressed in the developing neural tube. The proposed endogenous role of NAT in folate metabolism, and its multi-allelic nature, indicate that its role in development should be assessed further.

A rapid novel method for the extraction of RNA from wild-type and genetically modified kanamycin resistant mycobacteria

RNA extraction from mycobacteria can be a difficult and time consuming process due to their unique mycolic acid cell wall composition and the short half life of RNA. Rapid cell wall disruption is essential to isolate intact high quality RNA. Genetically modified Mycobacteria smegmatis resistant to kanamycin demonstrate an altered cell wall composition which impairs the quality of RNA obtained from these mycobacteria. In this report we describe a method of RNA extraction using the detergent Catrimox-14 resulting in high yields of pure, undegraded RNA in less than 1 h. Yields of 25-30 microg RNA per 1x10(9) cells were consistently obtained from both wild-type and genetically modified M. smegmatis. The integrity of this RNA is demonstrated by gel electrophoresis, Northern blot and cDNA analysis.

A method for genotyping murine arylamine N-acetyltransferase type 2 (NAT2): a gene expressed in preimplantation embryonic stem cells encoding an enzyme acetylating the folate catabolite p-aminobenzoylglutamate

Mice have three arylamine N-acetyltransferase (NAT) isoenzymes (NAT1, NAT2, and NAT3) of which NAT2 is known to be polymorphic. Humans have two polymorphic isoenzymes, NAT1 and NAT2. The isoenzymes mouse NAT1 and human NAT2 are expressed predominantly in the liver and intestine and are involved in drug and xenobiotic metabolism. Mouse NAT2 and human NAT1 have a widespread tissue distribution and the folate catabolite p-aminobenzoylglutamate (pAB-Glu) has been proposed as a candidate endogenous substrate. All mice have detectable NAT2 activity, although inbred mouse strains have either a fast or slow acetylator phenotype conferred by the presence of either NAT2*8 (fast) or NAT2*9 (slow) alleles at the NAT2 locus. In this report, we describe a simple method for distinguishing these murine alleles by polymerase chain reaction followed by restriction fragment length polymorphism analysis. We compared the tissue distribution of the acetylation activity found in both fast (C57BL/6J) and slow (A/J) acetylating strains of mice using pAB-Glu and p-aminobenzoic acid as probe substrates. It has previously been demonstrated that murine NAT2 is expressed in the neural tube prior to closure (Stanley L, Copp A, Rolls S, Smelt V, Perry VH and Sim E, Teratology 58: 174-182, 1998). We demonstrate here that murine NAT2 is expressed in preimplantation embryonic stem cells. Murine NAT2 is likely to be expressed prior to neurulation and this may be important in view of the protective role of folate in neural tube development.

N-acetylation of the heterocyclic amine batracylin by human liver

Batracylin (8-aminoisoindolo[1,2-b]quinazolin-12(10 H)-one; BAT) is a heterocyclic amine that exhibits antitumor activity in a number of in vivo and in vitro models. The acetyl product has been implicated in BAT toxicity in animals, cells, and bacteria. The ability of human N-acetyltransferase (NAT) to form this product was investigated. Nine human liver samples were analyzed for NAT1 and NAT2 genotypes. Seven of the samples possessed at least one NAT1*4 allele. Three samples contained one or more NAT2*4 allele and were classified as rapid acetylators. The remaining six had two alleles associated with the slow phenotype. NAT activities were evaluated with BAT, sulfamethazine (SMZ), a preferential substrate for human NAT2, and p-aminobenzoic acid, a substrate for NAT1. BAT activities in the nine donor samples ranged from 14.9 to 0.56 nmol/min/mg. The mean apparent K(m) values in rapid acetylators for BAT, SMZ, and p-aminobenzoic acid were 6.59 +/- 3.21, 278 +/- 69.4, and 31.2 +/- 12.5 microM, respectively. The apparent K(m) values for slow acetylators did not differ from the rapid acetylator phenotype. However, a significant difference in the apparent V(max) for BAT and SMZ was observed between rapid and slow acetylators. Comparing the apparent intrinsic clearance (V(max)/K(m)) for BAT and SMZ, a significant correlation (r(2) = 0.97, p <.001) was observed. These data demonstrate that BAT N-acetylation is similar to SMZ, and suggests that BAT is a preferential substrate for human NAT2. Thus, rapid acetylators would be more likely to develop toxicity when exposed to this drug.

Arylamine N-acetyltransferase type 2 (NAT2), chromosome 8 aneuploidy, and identification of a novel NAT1 cosmid clone: an investigation in bladder cancer by interphase FISH

Two genes (arylamine N-acetyltransferase types 1 and 2, NAT1 and NAT2), which are known to metabolize bladder carcinogens, are located on chromosome band 8p22. Alterations in chromosome 8, including deletions of 8p, occur frequently in many epithelium-derived tumors. In this study, fluorescence in situ hybridization (FISH) was used for study of the relationship between chromosome 8 deletions in the region of NAT1 and NAT2 and grade and stage of tumor in bladder cancer. Cells from 52 bladder tumors were examined by dual-labeling FISH with a centromere 8-specific probe and a cosmid probe for NAT2. A more limited number were examined for loss with both the NAT2 probe and a newly constructed NAT1-specific cosmid. Loss of NAT2 was found in 6/52 patients in more than 30% of cells, and in 10/52 in 10%-30% of cells examined. Six samples also showed loss of NAT1, indicating that the region of deletion spans at least the distance of the two genes. No obvious correlation between loss of NAT genes with grade and stage of tumor was evident. Interestingly, 17/52 (32%) tumors showed an increased copy number of chromosome 8, with tumors of low stage showing relatively smaller increases of chromosome 8. Loss of 8p22 and genetic instability involving chromosome 8 indicate that this chromosome is important in bladder cancer and that NAT genes will act as important genetic landmarks in defining deletions in this disease. Genes Chromosomes Cancer 25:376-383, 1999.

Cloning and characterization of arylamine N-acetyltransferase genes from Mycobacterium smegmatis and Mycobacterium tuberculosis: increased expression results in isoniazid resistance

Arylamine N-acetyltransferases (NATs) are found in many eukaryotic organisms, including humans, and have previously been identified in the prokaryote Salmonella typhimurium. NATs from many sources acetylate the antitubercular drug isoniazid and so inactivate it. nat genes were cloned from Mycobacterium smegmatis and Mycobacterium tuberculosis, and expressed in Escherichia coli and M. smegmatis. The induced M. smegmatis NAT catalyzes the acetylation of isoniazid. A monospecific antiserum raised against pure NAT from S. typhimurium recognizes NAT from M. smegmatis and cross-reacts with recombinant NAT from M. tuberculosis. Overexpression of mycobacterial nat genes in E. coli results in predominantly insoluble recombinant protein; however, with M. smegmatis as the host using the vector pACE-1, NAT proteins from M. tuberculosis and M. smegmatis are soluble. M. smegmatis transformants induced to express the M. tuberculosis nat gene in culture demonstrated a threefold higher resistance to isoniazid. We propose that NAT in mycobacteria could have a role in acetylating, and hence inactivating, isoniazid.

Cyclin E2, a novel G1 cyclin that binds Cdk2 and is aberrantly expressed in human cancers

A novel cyclin gene was discovered by searching an expressed sequence tag database with a cyclin box profile. The human cyclin E2 gene encodes a 404-amino-acid protein that is most closely related to cyclin E. Cyclin E2 associates with Cdk2 in a functional kinase complex that is inhibited by both p27(Kip1) and p21(Cip1). The catalytic activity associated with cyclin E2 complexes is cell cycle regulated and peaks at the G1/S transition. Overexpression of cyclin E2 in mammalian cells accelerates G1, demonstrating that cyclin E2 may be rate limiting for G1 progression. Unlike cyclin E1, which is expressed in most proliferating normal and tumor cells, cyclin E2 levels were low to undetectable in nontransformed cells and increased significantly in tumor-derived cells. The discovery of a novel second cyclin E family member suggests that multiple unique cyclin E-CDK complexes regulate cell cycle progression.

Expression of arylamine N-acetyltransferase in human intestine

BACKGROUND

Arylamine N-acetyltransferases in humans (NAT1 and NAT2) catalyse the acetylation of arylamines including food derived heterocyclic arylamine carcinogens. Other substrates include the sulphonamide 5-aminosalicylic acid (5-ASA), which is an NAT1 specific substrate; N-acetylation of 5-ASA is a major route of metabolism. NAT1 and NAT2 are both polymorphic.

AIMS

To investigate NAT expression in apparently healthy human intestines in order to understand the possible role of NAT in colorectal cancer and in the therapeutic response to 5-ASA.

METHODS

The intestines of four organ donors were divided into eight sections. DNA was prepared for genotyping NAT1 and NAT2 and enzymic activities of NAT1 and NAT2 were determined in cytosols prepared from each section. Tissue was fixed for immunohistochemistry with specific NAT antibodies. Western blotting was carried out on all samples of cytosol and on homogenates of separated muscle and villi after microdissection.

RESULTS

NAT1 activity of all cytosols was greater than NAT2 activity. NAT1 and NAT2 activities correlated with the genotypes of NAT1 and NAT2 and with the levels of NAT1 staining determined by western blotting. The ratio of NAT1:NAT2 activities showed interindividual variations from 2 to 70. NAT1 antigenic activity was greater in villi than in muscle. NAT1 was detected along the length of the villi in the small intestine. In colon samples there was less NAT1 at the base of the crypts with intense staining at the tips.

CONCLUSIONS

The interindividual variation in NAT1 and NAT2 in the colon could affect how individuals respond to exposure to specific NAT substrates including carcinogens and 5-ASA.

Height, weight, and body fat: assessments of covariation based on visual information or reported correlations

College students' intuitive judgments about covariations between height, weight, and body fat were assessed in three experiments using responses to a series of propositional statements as the dependent variable. In Exp. 1, judgments were rendered without explicit exposure to a prior database. In Exps. 2 and 3, however, databases were studied prior to these judgments. Remarkable consistencies in judgments of weight and body fat, height and weight as well as of height and body fat were obtained across experiments. At best, there was little evidence that the databases influenced the judged covariations among these variables. Whereas judgments about weight and body fat were unambiguous and consistent with the actual positive correlation between weight and body fat, judgments about height and weight as well as height and body fat were less clearcut. What was clear, however, was that these judgments were highly similar. Implications of these findings from previous research that suggest that presence of a perceived negative correlation between height and body fat are discussed.

Relations of bone and blood lead to cognitive function: the VA Normative Aging Study

The relationship between performance on cognitive tasks and circulating levels of lead in blood and accumulated levels of lead in bone was examined in 141 middle-aged and elderly men from a longitudinal study of aging. The mean (SD) blood lead level was low [5.5 (3.5) micrograms/dl], and mean patella and tibia lead levels were 31.7 (19.2) and 22.5 (12.2) micrograms/g bone mineral, respectively. Cognitive tests measured attention, perceptual speed, memory, language, and spatial copying. Regression models, adjusted for age and education, demonstrated that men with higher levels of blood lead recalled and defined fewer words, identified fewer line-drawn objects, and required more time to attain the same level of accuracy on a perceptual comparison test as men with the lowest level of blood lead. Men with higher levels of blood and bone (tibia) lead copied spatial figures less accurately; men with higher levels of bone (tibia) lead had slower responses for pattern memory. These findings suggest that low levels of lead contribute to impairments in cognitive function among elderly men.

Antibodies to the tyrosine phosphatase-like protein IA-2 are highly associated with IDDM, but not with autoimmune endocrine diseases or stiff man syndrome

Antibodies to the 40 kD antigen (identified as tyrosine phosphatase IA-2) and glutamate decarboxylase (GAD65) are strongly associated with insulin dependent diabetes mellitus (IDDM). However, antibodies to GAD (GADA) can appear in the absence of IDDM, particularly in stiff man syndrome (SMS) and in some individuals with autoimmune polyendocrine syndrome type II (APS II) and organ specific autoimmune diseases. The aim of this study was to compare the specificity of IA-2 antibodies (IA-2A) and GADA for IDDM by determining their frequency in different patient groups. IA-2A were present in 64/114 (56%) IDDM patients and 9/19 (47%) APS II patients with IDDM but in only 4/28 (14%) SMS patients. 1/24 (4%) APS II patients without IDDM and 1/113 (0.9%) patients with organ specific autoimmune disease had low level IA-2A. In contrast GADA were present in 77/114 (68%) IDDM patients and 17/19 (89%) APS II patients with IDDM, but also in 25/28 (89%) SMS patients, 5/24 (21%) APS II patients without IDDM and 22/113 (19%) patients with organ specific autoimmune diseases. Furthermore, within the group of new onset IDDM, IA-2A seemed to be associated with ICA and age: 63% of ICA positive IDDM patients had IA-2A (74% had GADA) increasing to 77% in the group below 20 years of age (69% for GADA). Our results demonstrate that IA-2A may be more specific for IDDM than GADA, as the latter are also present in patients with SMS, APS II without IDDM and organ specific autoimmune diseases. IA-2A were less frequent in older patients with IDDM than GADA or ICA. A combination of IA-2A and GADA detected 84% of total and 93% of ICA positive IDDM patients.