Alkaline hydrolysis of mouse-adapted scrapie for inactivation and disposal of prion-positive material.

Prion diseases such as bovine spongiform encephalopathy, chronic wasting disease, and scrapie pose serious risks to human and animal health due to a host of disease-specific factors, including the resistance of infectious prions (PrP(Sc)) to natural degradation and to most commercial inactivation procedures. In an attempt to address this concern, a mouse model was used to compare the efficacy of an alkaline hydrolysis process with a simulated continuous-flow rendering treatment for disposal of PrP(Sc)-infected biological material. Female C57/BL6 mice (N = 120) were randomly divided into 4 treatment groups (n = 30), and each mouse was injected intraperitoneally with their designated treatment inoculum. Treatment groups 1 and 2 served as the positive and negative controls, respectively. Group 3 was inoculated with rendered scrapie-positive mouse brain material to investigate the effectiveness of simulated continuous-flow rendering practices to reduce or eliminate PrP(Sc). Group 4 was inoculated with hydrolyzed scrapie-positive mouse brain material to determine the sterilizing effect of alkaline hydrolysis on PrP(Sc). Mice were monitored for overt signs of disease, and those showing clinical signs were killed to prevent undue suffering. Brains were obtained from all mice that died (or were killed) and analyzed with an ELISA for the presence of PrP(Sc). Results indicated that the simulated continuous-flow rendering treatment used for preparing the rendering treatment group inoculum failed to completely eliminate PrP(Sc). Rendering delayed, but did not stop, clinical mouse-adapted scrapie transmission. Compared with positive controls, the rendering treatment group experienced an approximate 45-d average delay in days to death (250 vs. 205 d for positive controls; P < 0.0001) and a death loss of 73.9% (P = 0.0094). Positive controls suffered 100% death loss. The results validated the efficacy of the alkaline hydrolysis treatment to inactivate all PrP(Sc) because no alkaline hydrolysis treatment group mice succumbed to the disease (P < 0.0001). Based on our results, alkaline hydrolysis should be considered by the animal rendering and beef packing industries as an alternative to incineration, landfill burial, and rendering for disposing of biological material potentially infected or contaminated with prion disease.

Epidemiological study of Yersinia enterocolitica in swine herds in Québec.

The objectives of this study were the identification of the different contamination sources of Yersinia enterocolitica, as well as the determination of the prevalence and the distribution of the different genotypes in swine herds. The owners of 20 farms, located in the Richelieu-Yamaska region, agreed to participate in the study. Each farm was visited a minimum of 5 times between May and October 1997, and, at each visit, 20 environmental and 10 fecal samples were collected. Yersinia enterocolitica isolates were identified, serotyped, and submitted to a genetic characterization by pulsed-field gel electrophoresis. The correlation coefficient (0.61) between prevalence in environment and in feces was significant (P = 0.004). Among the 153 positive samples, 93.5% belonged to serotype 0:3. The comparison of PFGE profiles revealed that all environmental Y. enterocolitica isolates had a profile identical to that of isolates recovered in feces from the corresponding farms. Also, when the genetic profiles of isolates recovered from feces collected at the first visit were compared with the profiles of isolates obtained from the subsequent visits, the same profile was observed on every farm. We concluded that environment does not represent the main source of contamination of swine by Y. enterocolitica and that, in most instances, the same strain persists in a barn from one production lot to another.

Yeast chromatin reconstitution system using purified yeast core histones and yeast nucleosome assembly protein-1.

Transcription regulation in the cell occurs in the context of chromatin. It follows that a thorough investigation of the mechanism of transcription regulation must take into account the role of chromatin structure. Through classical and molecular genetic experiments in yeast, great strides have been made in understanding the role of chromatin in eukaryotic gene regulation. To achieve a more detailed understanding of the biochemical mechanism of transcription regulation, a yeast chromatin reconstitution system is needed. This need drove us to develop a yeast core histone purification procedure for the reconstitution of these histones into chromatin templates using components wholly derived from yeast. We have purified native yeast core histones in milligram quantities and we have shown these histones to be competent for reconstitution of chromatin templates using yeast nucleosome assembly protein-1. This accomplishment sets the stage for studies using the full power of yeast as an experimental organism to investigate the role of chromatin in transcription regulation.

[Smith-Lemli-Opitz syndrome; a special defect in cholesterol metabolism]. / Het Smith-Lemli-Opitz-syndroom; een bijzonder defect in het cholesterolmetabolisme.

In a male neonate dysmaturity, microcephalia, a high nasal bridge, a long philtrum, broad dental ridges, schisis of the palatum molle, retrognathia, a small penis with a chorda, a small scrotum, bilateral inguinal hernia and bilateral syndactyly of the second and third toes were observed. The presence of the Smith-Lemli-Opitz (SLO) syndrome was suspected. By gas chromatography a severely decreased plasma cholesterol level (0.27 mmol/l) was found and an increased plasma 7-dehydrocholesterol level (0.24 mmol/l). The SLO syndrome is caused by a block in the cholesterol biosynthesis due to the autosomal recessive deficiency of 7-dehydrocholesterol reductase. The patient's condition improved with use of a cholesterol-enriched diet.

Magnitude of orthodontic forces and rate of bodily tooth movement. An experimental study.

The relationship between the magnitude of a constant continuous orthodontic force and rate of bodily tooth movement was studied. In 25 young adult male beagle dogs, lower third premolars were extracted and bone markers were implanted in the mandible. Sixteen weeks later, an orthodontic appliance was placed, and elastics exerting 50, 100, or 200 gm were attached to the lower second premolar to produce bodily distalization. In each dog, different forces were used on the left and the right sides. As a control group, orthodontic appliances were placed without elastic on eight sides. Tooth movement was measured directly with a digital caliper twice a week during 16 weeks. Resulting curves could be divided in four phases. Large individual differences were found in the rate of tooth movement. Tooth movements on the left and right sides of each dog, however, were highly correlated. No significant differences in the duration of each phase nor in the mean rate of tooth movement during each phase were found between the three force groups. Maximum rate of tooth movement was about 2.5 mm per month in all force groups. There were no significant differences in the mesial movement of the anchorage unit between the force groups. It is concluded that under the circumstances of this study magnitude of force is not decisive in determining the rate of bodily tooth movement, but individual characteristics are.

Capillary GC-ECD and ECNI GCMS characterization of toxaphene residues in primate tissues during a feeding study.

Toxaphene is a pesticide whose use was banned in North America because of concerns regarding its toxicity. To obtain better data on the metabolism and toxicity of toxaphene in primates, a one year feeding study was carried out in cynomologous monkeys at a dose of 1 mg/kg/day for one year. Levels of toxaphene residues in blood and adipose tissue during the dosing period were measured by GC-ECD and ECNI GCMS. The dosing toxaphene mixture was found to be extensively metabolized. Four chlorinated bornane congeners were the predominate residues found in the tissue samples. Blood levels of toxaphene residues plateaued at 40 ppb, adipose levels at approximately 4000 ppb. Kidney, liver, feces and urine were analyzed for toxaphene residues after necropsy.

Congenital glaucoma in a child with partial 1q duplication and 9p deletion.

A case of partial duplication of chromosome 1 (1q41-qter) and partial deletion of chromosome 9 (9p24-pter) with infantile congenital glaucoma is reported. The histopathology of the eyes is described. The clinical findings ascribed to trisomy 1q and partial monosomy 9p are summarized and compared to this case. As this is the second report of a patient with monosomy 9p24-pter and congenital glaucoma, it may indicate localization of a gene involved in congenital glaucoma in this region of the human genome.

Properties of ornithine decarboxylase in human colorectal adenocarcinomas.

Ornithine decarboxylase (ODC) activity was measured in colon adenocarcinomas and adjacent normal-appearing colon mucosa from a total of 40 patients undergoing surgical resections. The enzyme activity was measured in the presence and absence of GTP, since recent work has demonstrated a GTP-activatable form of ODC in some murine and human tumors. In general, ODC specific activity was higher in adenocarcinomas than in adjacent normal-appearing mucosa. Of greater interest, however, was the finding that 13 of 40 tumors and 3 of 40 mucosae contained a GTP-activatable form of ODC. These are minimal estimates of the proportion of tissues positive for this enzyme form, since a multiple sampling protocol indicated that expression of a GTP-activatable ODC was not uniform throughout a given tumor. Chromatographic analyses of tumor extracts revealed the presence in some tumors of multiple size forms of ODC, only some of which were activated by GTP. Enzyme kinetic data indicated that the multiple forms of ODC can have different affinities for L-ornithine and that GTP can "normalize" the aberrant kinetic properties of these forms. While there was no statistically significant correlation of the presence of a GTP-activatable ODC with stage of disease, analysis of our data revealed a positive association of a GTP-activatable ODC with tumor site; a much higher percentage of tumors of the cecum contained this ODC isoform than tumors of other colonic segments (64% versus less than or equal to 25% for other sites). These results demonstrate (a) the presence of a functionally distinct form of ODC in some human colon adenocarcinomas and (b) a distinct regional distribution of this ODC form within the colon. We suggest this alteration in a key enzyme in the growth-associated pathway of polyamine biosynthesis may play a role in colon tumor progression.

Telemedical imaging--the diagnostic imaging department's perspective.

A survey of Alberta hospitals indicates a provincial perspective of the relationship between telemedical imaging and the diagnostic imaging department. Current image transmission technology literature demonstrates a degree of correlation with the results determined from the telemedical imaging survey. After presenting a brief definition of telemedical imaging, the areas assessed include: relative need, functional objectives, cost effectiveness, user-technology concerns and transmission system expectations.

[Management of the violent patient : description of organization of a living environment and of its model of clinical intervention.]. / Le management du patient violent : description de l'organisation d'un milieu de vie et de son schème d'intervention clinique.

The article deals with the following aspects : principles and values upon which intervention plans recommended for violent patients are based, as well as a description of the clinical framework, at work on two levels. The first level is that of the patient aiming for autonomy and taking responsibility. For this purpose, we developed various mechanisms and tools. These are : the individualized-care plan, the reference person, the resource person, the life situation and re-educative activities, clinical intervention specifically for aggressivity (physical and psychological intervention for the resident and the personnel when there is acting out). The second level of the framework concerns is concerned with care personnel developing on their own ways to deal with violence manifested by the patient. We list several ways to help personnel with this difficult task.

Interlaboratory study on determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin in fish.

An interlaboratory round robin study was carried out to estimate the reliability of data on 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in fish. Using different methods, 13 laboratories (4 Canadian, 9 American) agreed to analyze 4 fish samples; 3 were Great Lakes salmonids containing bio-incurred levels of TCDD below 100 ppt and the fourth was an ocean fish fillet containing no measurable TCDD. Samples were sent as freeze-dried portions as it was shown that no change of TCDD occurred by this sample preparation. Results were normalized between laboratories by supplying each with an aliquot of the same 2,3,7,8-TCDD standard. Eight laboratories reported a set of results of which one set was rejected. Values from the 7 remaining laboratories for the 3 positive fish showed mean concentrations in pg/g (ppt) and (CV, %) of 61.2 (13.9), 30.4 (18.4), and 32.3 (25.4). Detection limits averaged 3.6 ppt and ranged between 1 and 10 ppt. No significant differences appeared in the concentration of 2,3,7,8-TCDD in fish samples from methods differing in the use of: (i) digestion or extraction techniques, (ii) high or low resolution mass spectrometry, and (iii) isomer specific or nonspecific separations. Overall recovery values using internal standards varied greatly (29-109%) even within the same laboratory and pointed to the need to use an internal standard to obtain precise results. Agreement among laboratories was good considering the level quantitated (ppt) and the diverse methodology.

Polyaromatic hydrocarbons as high-performance liquid chromatographic calibration standards for the low level determination of chlorinated dibenzo-p-dioxins and chlorinated dibenzofurans in biological samples.

A series of polyaromatic hydrocarbons (PAHs) has been used to calibrate the retention times of chlorinated dibenzo-p-dioxins (dioxins) and chlorinated dibenzofurans (furans) on high-performance liquid chromatography (HPLC) in the ultra-trace analysis of biological samples. Fraction collection is then based on the HPLC retention times of the PAHs without the need for the dioxins or furans. Because of the variety of PAHs, a particular one can be chosen that will co-chromatograph near any given dioxin or furan. It has been shown that the effect of solvent changes and sample co-extractives on the HPLC eluting properties of the PAHs is minimal. The use of PAHs as secondary standards for HPLC calibration in dioxin trace analysis diminishes both the potential for contamination of the sample by the standard and the handling of the chlorinated dioxins and furans. The PAH standards could also be useful for those laboratories who are limited in their safety facilities or in the number and amount of dioxin-furan standards available to them.

Composite sampling in the determination of pyrethrins in fruit samples.

A residue method is described for measuring up to 6 naturally occurring pyrethrins in several varieties of fruits. Fresh samples are extracted into acetone, partitioned between water and hexane-dichloro-methane, and cleaned up by adsorption on a Florisil column followed by elution with acetone-hexane (15 + 85). Residues are detected and quantitated by gas chromatography with electron capture detection. Detection limits for single 10 g samples are about 10-30 ng/g. The method was applied to a survey of pyrethrins in fruit samples. Because of the high tolerance (1 ppm) allowed for pyrethrins, the expected low incidence, and the low detection limits of the method, composite samples (up to 5-6) of fruit were used to quickly determine residue levels. This procedure allowed 130 samples to be processed in the time normally needed for 30-40. Provided the above conditions can be met, composite sampling is proposed as an attractive approach to data gathering in pesticide residue analysis.

[Histological and morphometric study of the development of the optic part of the compound eye of the Enallagma boreale Selys (Odonata: Coenagrionidae)]. / Etude histologique et morphométrique de la croissance de la partie optique de l'oeil composé d'Enallagma boreale Selys (Odonata: Coenagrionidae).

The morphology of the optical part of the Enallagma boreale Selys compound eye remains unchanged during its post-embryonic development. The cornea, composed of the epi-, exo- and endocorne, is in perfect continuity with the larval cephalic cuticle. Consequently these two structures possess the same three layers and have a similar process formation. But, the measurements from cephalic endocuticle and endocornea of the adult differ significantly from each other. The latter has a lamellar aspect. The nuclei cornea reaches its morphometric characteristics as early as the pre-emergence stage. The nuclei of the two primary pigment cells which have maintained their epidermic nature, are located at each side of the apex of the crystalline cone. The nuclei of the secondary pigment cells are uniformly distributed in the optical and photosensitive parts. The larval and adult crystalline cones differ morphometrically. The larval one is longer and narrower and reaches its adult characteristics just before emergence. Statistical tests do not show any significant difference between the dorsal and the ventral parts of the larval and adult compound eye.

Chemical confirmation of diethylstillbestrol residues in beef livers.

A simple chemical technique was developed to confirm the presence of diethylstillbestrol (DES) residues in beef tissues at 2 ppb. The DES-trifluoroacetate (TFA) from the previously published method is hydrolyzed in water-methanol at 55 degrees C for 20 min to free DES which is then extracted into benzene. Trimethylamine and a small amount of heptaafluorobutyric (HFB) anhydride are added to effect the smooth conversion of DES to its di-HFB at either room temperature or 60 degrees C. DES-HFB is determined by gas-liquid chromatography with electron capture detection on a 6' x 4 mm id column of 3% OV-210 at 190 degrees C. This procedure yields 2 peaks for DES-HFB (retention times 2.7 and 4.8 min for the cis and trans, respectively) which are resolved from the 2 DES-TFA peaks (retention times 2.3 and 3.3 min for cis and trans, respectively). The sensitivity of detection of DES-HFB is increased by a factor of 4-5 over that for DES-TFA. This chemical technique was successfully applied to purified extracts of beef liver fortified with DES at 2-10 ppb with recoveries from 60 to 110%.