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The effects of tail suspension hypokinesia on the gene expression for TGF-β2at different sites within bone were evaluated. TGF-β2mRNA signal levels were determined quantitatively by an image analysis system. The osteopenia induced by tail suspension was verified by histomorphometry. In the periosteum of nonsuspended control rats, TGF-β2mRNA was highly expressed in the preosteoblasts and osteoblast-rich cambial layers; very little signal was present within the middle and outer fibroblastic layers. Gene expression was significantly reduced in suspended rats, and this was evident both in terms of the number of silver grains in unit area or length of tissue and in each osteoblast and preosteoblast. Hypokinesia also reduced the expression of TGF-β2mRNA level in cortical and trabecular bone osteocytes, but did not adversely affect the mRNA level in chondrocytes in growth plate. The results affirm the site-specific response of TGF-β2gene expression in rats, and suggest that the cortical and trabecular bone osteopenia associated with hypokinesia in rats may be associated with a deficit in osteoblastic and osteocytic TGF-β2level.

The potential of the finite element method as a computational aid for making objective clinical decisions has not yet been exploited due to the unreliability of the results obtained. The main reasons for this may be attributed to the poor quality of the finite elements available in the conventional softwares, improper modeling of the three dimensional problem, and errors introduced by incorrect representation of geometry and material properties. Herein, we report an attempt to derive a three-dimensional finite element model for the adult human femur which permits reliable representation of the local stress patterns. The geometry was obtained by serial computed tomography scans. The mechanical properties were based on laboratory tests and information available in the literature. The analysis is performed with a new generation software. Preliminary results suggest that the scheme could be automated and used for in vivo analysis.

The circadian patterns of bone collagen formation were studied in vitroto ascertain whether the biorhythmic profiles previously measured in vivoreflect true differences in collagen synthesis. Alteration of amino acid pool sizes did not negate the circadian-stage differences in bone collagen production. Evaluations of proline uptake and transport, as well as collagenous protein turnover, demonstrated that the intracellular assembly and secretion of bone collagenous protein during the dark span is truely decreased relative to that during the light period. It was further affirmed that PTH is essential for maintenance of the normal circadian collagen synthesis rhythms.

The bone-resorbing activity of prostaglandin was assessed in neonatal mouse calvaria maintained in culture as well as in the bones of adult mice in vivo.In an in vitro45Ca-release bioassay, PGE2, the most active compound, produced a maximal stimulation of radiocalcium bone depletion of 89% versus 38% for PGF2αand 12% for PGA1. Daily intraperitoneal injection of 10 μg of 16,16-dimethyl-PGE2-methyl ester, a long-acting synthetic analog of PGE2, in several groups of C57/B1/6J mice produced a mean 33% loss of trabecular bone and a 140% increase in the area of bone lined by osteoclasts. Moreover, treatment of 4-month-old mice with di-M-PGE2for 4 days caused a mean 15% depletion of bone calcium. There were no significant changes in blood calcium with the protocol employed.

Young, growing rats which had been chronically (2 weeks) adrenalectomized or parathyroidectomized were used to define the roles of the adrenal and parathyroid glands on the maintenance of normal circadian rhythms of DNA, collagen and non-collagen protein synthesis in the skeleton. The animals were conditioned to food being available ad libitumand to 12 h light: 12 h darkness (lights on from 08.00 to 20.00 h). The pace of DNA, collagen and non-collagen protein synthesis in different regions of the tibia (tibial growth cartilage, metaphysial bone and diaphysial bone) was measured by the in-vivo incorporation of tritiated thymidine (1 h) and radioactive proline (48 h). In intact rats there were no regional differences in the phasing of the circadian profiles; peak DNA and non-collagen protein synthesis occurred at the onset of the dark period while peak collagen synthesis occurred during the middle of the period of light. Adrenalectomy selectively abolished the regional DNA synthesis rhythms without altering the phases of the serum Ca and phosphorus (P) rhythms, which peak at mid-day and at the onset of darkness respectively. Parathyroidectomy abolished the regional rhythms for collagen and non-collagen protein synthesis and serum Ca rhythms, without altering the phase of the serum P and corticosterone rhythms. Dietary Ca-lactate supplements, which raised serum Ca levels towards normal in parathyroidectomized rats, were able to correct serum corticosterone values but did not normalize bone collagen and non-collagen protein synthesis values. These data indicate that the adrenal rhythm governs the proliferative activities of bone and cartilage cells, and that parathyroid hormone is essential to maintain normal collagen and non-collagen protein synthesis rhythms.J. Endocr.(1984) 103, 49–57

The possible use of Dienes' phenomenon for typing proteus strains as an aid to bacteriological monitoring of barrier-maintained animal units was investigated. It was rare for more than 1 Dienes' type to be isolated from an individual animal. A persistent relationship between 1 or 2 Diene's types and each strain of animal was demonstrated, although these same types were shown to be capable of causing clinical disease in their normal host. The findings suggest that Dienes' phenomenon may be of value in detecting outside contamination of barrier-maintained animals and also might usefully be applied to experimental epidemiological studies.

A wild rat (Rattus norvegicus) killed in the vicinity of a food store in which pathogen-free animal diet was stored, was found to be heavily infected with Capillaria hepaticaand Hymenolepis diminuta. Sacks of diet from the store were found to be contaminated with rodent faeces containing eggs of these parasites. The possibility of Capillaria hepaticaeggs infecting animals within a specified-pathogen-free or minimum disease unit and the likelihood of detecting such an infection are discussed. Recommendations are made which would reduce the risk of pathogenic organisms entering an animal unit with the diet.

In an epidemic outbreak of salmonellosis associated with Salmonella montevideoin 6 mouse colonies, most deaths occurred in BALB/c and ASI mice, although the carrier rate was similar in other mouse strains. The salmonella was eradicated from ASI mice of 4-6 weeks old, and the carrier rate considerably reduced at 12-26 weeks of age, by use of oral oxytetracycline in conjunction with strict hygiene measures. Housing mice on wire grids instead of wood shavings did not affect the efficacy of the treatment.

An outbreak of fatal enteritis in CBA/ca mice, associated with Salmonella livingstone, was successfully treated by administration of tetracycline in drinking water together with careful observation of hygienic routines.

A study was made of the cultural and biochemical characteristics of 17 strains of Actinobacillusisolated from laboratory rats and hamsters. 2 types were recognized which differed in their urease reaction and colony colour on blood agar. The results obtained suggest that one was Actinobacillus equulibut the other could not be identified as belonging to a described species. The characteristics of both organisms are such that they could be confused with Pasteurella pneumotropica. One of the types was Isolated from tapwater.