The calcium-activated cell-adhesion proteins tenascin, E-cadherin and the purinergic (P2X) calcium channel receptors are expressed in an identical spatial and temporal pattern in uterine epithelium in the rat during implantation. On Day 1 of pregnancy (estrous), a diffuse cytoplasmic and specific basement membrane label for each of the proteins was observed throughout the uterine epithelium. On Day 3 of pregnancy, a specific and prominent lateral plasma membrane label for each protein was seen. At the time of implantation on Day 6, an additional and significant increase in the label for each was observed on the apical epithelium. At this time, the label for tenascin in the apical epithelium was increased 2.1-fold (p < 0.0004), that of E-cadherin was increased 2.5-fold (p < 0.0001) and the P2X receptor label was increased 2.0-fold (p < 0.0001). These observations suggest a major role for the calcium-activated adhesion proteins tenascin and E-cadherin in attachment and implantation, with ionic calcium for protein activation possibly provided by the P2X calcium channels. These events occur along the entire length of the uterine epithelium in preparation for blastocyst adhesion.

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PubMedDate not supplied

Reduction in plate strain by addition of an intramedullary pin.

OBJECTIVE: The purpose of this study was to determine the strain sparing effect of a bone plate and rod system compared with a bone plate alone. STUDY DESIGN: Mathematical analysis and in vitro modeling of implant-bone constructs. Implants were instrumented with uniaxial strain gauges. ANIMALS OR SAMPLE PREPARATION: Five pairs of canine femurs. METHODS: Bone plates were instrumented with two 350-ohm strain gauges. The bone plates were used to bridge a simulated fracture gap in five pairs of canine femurs. In one femur of each pair, a bone plate alone was used to bridge the gap; in the opposite femur, a bone plate and intramedullary rod combination was used. Each specimen was mounted on a custom jig and loaded in an axial servohydraulic testing machine. A constantly increasing compressive load was applied at the rate of 0.7 cm/sec. Strains at 400.5 N were recorded and analyzed using Wilcoxon's signed rank test. Mathematical modeling was done using parallel beam theory. RESULTS: Stress reduction in the plate and rod system was twofold compared with the plate alone (P = .059). As important, based on stress reduction in the plate, the fatigue life of the plate/rod system increased 10-fold over the plate system alone and was greater than 10-fold at higher absolute stress values. Mathematical analysis of the plate/rod system was similar to that seen with the in vitro analysis. CONCLUSIONS: The combination of a bone plate and intramedullary pin was superior in reducing plate stress when compared with the plate alone and functioned as two beams acting in concert. CLINICAL RELEVANCE: Stabilization of comminuted fractures by bridging the zone of fragmentation with a bone plate without anatomic reduction of each fragment is a useful method of managing this type of injury. Addition of an intramedullary pin reduces the stress applied to the plate and thereby extends the fatigue life of the bone plate.

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PubMedDate not supplied

Correlation of clinical, radiographic, and surgical localization of intervertebral disc extrusion in small-breed dogs: a prospective study of 50 cases.

OBJECTIVE: To compare prospectively clinical, radiographic, and surgical findings of intervertebral disc extrusion (IDE) localization in small-breed dogs and to determine the best means of lesion localization for the purpose of hemilaminectomy. STUDY DESIGN: Clinical, radiographic, and surgical findings of small-breed dogs with thoracolumbar IDE were prospectively compared for agreement on lesion localization. SAMPLE POPULATION: 50 small-breed dogs with IDE treated at the three participating veterinary hospitals were included in the study if no other confounding diseases were identified and if the owner gave permission for diagnostic tests and surgery. METHODS: Clinical and surgical findings were recorded by the surgeon assigned to the case. Radiographic studies were evaluated independently by two radiologists blinded as to the clinical and surgical findings. kappa values and 95% confidence intervals were calculated for agreement on lesion localization by clinical, radiographic, and surgical means and for agreement between radiologists. RESULTS: kappa values for agreement of lesion localization were as follows: clinical versus surgical, 0.595; radiologist A versus radiologist B, 0.81; radiologist A versus surgical findings, 0.60; radiologist B versus surgical findings, 0.71. Both radiologists' interpretation of IDE localization agreed with surgical localization in 60% of cases. CONCLUSIONS: Clinical lateralization of IDE was found to be the least reliable factor of those studied for determining on which side the hemilaminectomy should be performed. Results of this study differ from those of previous studies examining the reliability of myelography to localize the site of IDE accurately. The results of this study further suggest that surgery may not be an absolute standard for determination of the localization of IDE in small-breed dogs. CLINICAL RELEVANCE: Intervertebral disc extrusion in small-breed dogs frequently results in bilateral distribution of extruded material. Computed tomography or magnetic resonance imaging may be necessary to delineate completely the distribution of extruded disc material in IDE.

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PubMedDate not supplied

Identification of the in vivo liver metabolites of (--)-delta 7-tetrahydrocannabinol produced by the mouse.

The major in vivo metabolites of (--)-delta 7-tetrahydrocannabinol were extracted from the livers of mice after a single intraperitoneal dose and were examined by combined gas-liquid chromatography-mass spectrometry. Twenty-six metabolites were identified; most of these appeared to be produced via epoxidation of the double bond, although the epoxides themselves were not detected. Major metabolites involved hydroxylation of the double bond, to give the isomeric 1 alpha- and 1 beta, 7-dihydroxyhexahydrocannabinols. Of these, the 1 alpha, 7-isomer was the major product and appeared to be produced by hydrolysis of 1 alpha, 7-epoxyhexahydrocannabinol. It was further oxidized to 1 alpha-hydroxyhexahydrocannabinol-7-oic acid. Rearrangement of the epoxide to the 7-aldehyde and subsequent reduction to either the 7-alcohol or oxidation to the 7-acid was another major metabolic route. Derivatives of all these metabolites, hydroxylated in the 2"-, 3"- and 4"-positions of the sidechain were also identified. Allylic hydroxylation, predominantly at position 6, was also observed, but this was a relatively minor route. Reduction of the double bond yielded the isomeric axial and equatorial hexahydrocannabinols in low yield.

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PubMedDate not supplied

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