Effects of ovariectomy in beagle dogs

Beagle dogs 3-7 years old were ovariectomized (n = 9) or sham operated (n = 6) and followed for 48 weeks with measurements of body weight, tibial shaft bone mineral content (BMC), and serum biochemistry. Following killing, measurements were made of bone strength and histomorphometry. Ovariectomy (OX) significantly reduced serum estrone and estradiol concentrations and their variability from month to month. There was a transient decrease in cortical BMC of the OX dogs during the first 12 postoperative weeks but no difference between the groups after 48 weeks. Serum osteocalcin was elevated, but there was little effect on serum alkaline phosphatase, Ca, P, or calcitonin. OX increased the number of tetracycline-labeled osteons in cortical bone but reduced the percent trabecular surface labeled with tetracycline. OX produced no significant changes in the composition of the bones or loss of cortical area, but a statistically significant 15% trabecular bone loss occurred in the spine. However, bone strength had not been significantly affected at the time of sacrifice.     

Acute renal rejection versus acute tubular necrosis in a canine model: MR evaluation

Findings of magnetic resonance (MR) imaging in acute renal rejection and acute tubular necrosis (ATN) were studied in dogs. On T1-weighted images, corticomedullary differentiation was absent in kidneys undergoing acute rejection. The loss of corticomedullary differentiation in these kidneys was secondary to a decrease in the relative signal intensity of the cortex, indicating prolongation of the T1 relaxation time of the cortex. In contrast, corticomedullary differentiation was preserved on T1-weighted images of autotransplanted kidneys and kidneys with ATN. MR imaging findings correlated with changes in water content in these three groups of kidneys. Kidneys undergoing acute rejection showed a marked increase in water content compared with kidneys in the other two groups. No change in fat content was found in any group.     

The effect of leukotriene antagonists, lipoxygenase inhibitors and selected standards on leukotriene-mediated allergic bronchospasm in guinea pigs

Leukotrienes (LT) C4, D4, and E4 are major contributors to the pathobiology of human bronchial asthma. Therefore, it is likely that compounds that antagonize the action or inhibit the formation of LTs will be useful therapeutic agents. We have studied the effects of LT antagonists, 5-lipoxygenase inhibitors and selected standards in a model of LT-mediated allergic bronchospasm in guinea pigs. Sensitized animals were pretreated with mepyramine, indomethacin and propranolol to eliminate the influence of histamine, prostaglandins, thromboxanes and circulating catecholamines. In these animals, inhalation of antigen resulted in a bronchospasm consistent with a LT-mediated response that was slow in onset, of long duration and was inhibited by the selective LTD4, antagonists FPL-55712, LY-171,883 and ICI-198,615. ICI-198,615 was approximately 50-times more potent than FPL-55712 by the intravenous and intratracheal routes. However, of thirteen compounds known to inhibit 5-lipoxygenase and LT biosynthesis in vitro only phenidone, piriprost and AA-861 were active in this in vivo model. The allergic bronchospasm was inhibited by bronchodilators (e.g. PGE2, aminophylline and forskolin) and by some mast cell stabilizers, but was otherwise insensitive to other pharmacological classes of compounds including calcium channel blockers and antagonists of serotonin, acetylcholine and platelet-activating factor. This model seems useful and reasonably selective for the evaluation of new antianaphylactic compounds that are LT antagonists. The inactivity of many 5-lipoxygenase inhibitors in this model suggests they do not inhibit LT formation in vivo.     

Avulsion of the posteromedial tibial plateau by the semimembranosus tendon: diagnosis with MR imaging

Two sports-related knee injuries resulted in small fractures at the posteromedial corner of the tibial plateau. Magnetic resonance imaging demonstrated findings consistent with an avulsion injury at the semimembranosus insertion, as well as a similar pattern of internal derangement in both cases.     

Hormonal control of the cervix in pregnant gilts. II. Relaxin promotes changes in the physical properties of the cervix in ovariectomized hormone-treated pregnant gilts

The effects of relaxin on the physical properties of both the uterine and vaginal portions of the cervix were studied between days 80 and 110 of pregnancy in ovariectomized gilts given progesterone to maintain pregnancy. In controls gilts the extensibility, lumen diameter, and wet weight of the uterine portion of the cervix were less than those of the vaginal portion of the cervix on day 80, but increased thereafter, and by day 110 did not differ (extensibility and wet weight) or approached (lumen diameter) those values of the vaginal portion of the cervix. When gilts were ovariectomized on either days 80 or 100 and given progesterone only (groups OP-100 and OP-110) extensibility, lumen diameter, and wet weight failed to increase in both the uterine and vaginal portions of the cervix. After replacement therapy with progesterone plus relaxin (groups OPR-100 and OPR-110), extensibility, lumen diameter, and wet weight increased to values as least as large as those in control groups in both portions of the cervix. In all groups the uterine portion of the cervix changed more dramatically than the vaginal portion. After hormone replacement therapy, blood levels of relaxin were moderately higher, and blood levels of progesterone were somewhat lower than those in control gilts. There was little or no difference in estrogen levels between ovariectomized and control gilts. We conclude that relaxin plays an important role in promoting increased growth and extensibility in both the uterine and vaginal portions of the cervix after day 80 of gestation in the gilt.     

Screening for hypercholesterolaemia in 10,000 neonates in a multi-ethnic population

An immunoassay was developed for the detection of hypercholesterolaemia in dried blood spots collected from 6-day-old neonates. Blood spot samples (9,673) were subjected to immunoturbidimetric assay to determine the levels of apolipoprotein B (apoB), an index of plasma low density lipoprotein, and of apolipoprotein A-1 (apoA-1), an index of plasma high density lipoprotein. Infants with raised apoB or a reduced apoA-1/apoB ratio were recalled, retested and, if appropriate, referred to the Vascular Risk Clinic at King's College Hospital for medical management. A total of 189 were recalled for further testing; of whom 82 (45%) attended the recall clinic. A group of 16 families (24 individuals) had abnormal lipid profiles; of these, 7 families (14 individuals) had lipid profiles consistent with inherited hypercholesterolaemia. Conclusion Neonatal screening for hypercholesterolaemia using blood spot apolipo- protein measurements is feasible but ethnic variations in disease prevalence must be considered in the design of a screening programme. Received: 2 September 1997 / Accepted in revised form: 22 February 1999