Biomedical subjects
Publications and source records attributed to D J Simmons.
A heavy growth of Staphylococcus aureus was isolated from kidney abscesses in rats from 2 inbred strains treated with corticosteroids. The S. aureus phage types which caused the abscesses are endemic in the rat breeding colonies. One strain of rat was more sensitive to the action of the corticosteroids.
Explore the source record for details and available documents.
The relationship between regional bone blood flow (measured using the hydrogen washout method) and regional osteoblastic activity (inferred from presence of osteoblasts on histological sections) was studied in the rabbit tibia. The rate of blood flow in epiphyses with marked osteoblastic activity (0.283 +/- .053 ml/min/ml) was significantly faster than that in epiphyses with minimal activity (0.097 +/- .007 ml/min/ml). Metaphyseal blood flow was significantly faster in areas with marked activity (0.253 +/- 0.040 ml/min/ml) than those with moderate (0.153 +/- .007 ml/min/ml) or minimal (0.126 +/- 0.013 ml/min/ml) osteoblastic activity. Diaphyseal bone blood flow was significantly faster in immature (0.082 +/- 0.005 ml/min/ml) than in mature (0.062 +/- 0.004 ml/min/ml) animals. The results indicate that there is a positive association between regional bone blood flow rate and osteoblastic activity in normal bone.
Explore the source record for details and available documents.
Bordetella bronchiseptica, isolated from rodent nasopharygeal swabs, failed to produce characteristic colonies after 24 hours incubation at 37 degrees C. 4-7 days incubation at 37 degrees C was required to achieve positive motility test results, when isolates later identified as B. bronchiseptica were tested by Craigie tube and soft agar stab methods. The biochemical tests used to identify suspected B. bronchiseptica are specified.
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.
Microradiographs of 5-micron sections of methyl methacrylate embedded undemineralized bone show poor resolution, but prestaining with silver nitrate increases the radioopacity of the calcified tissues to soft x-rays without masking regional differences in microscopic mineralization. Identical results are achieved using aqueous (pH 5.8 and 7.5) or ammoniacal solutions (pH 7.9). Atomic absorption spectrometry detected no loss of calcium from the sections during staining. Osteoid in plastic-embedded bone is not rendered radiopaque by this technique even after prolonged staining times (5 min-2 hr).
The circadian control of bone and cartilage induction in calcified, surface-decalcified and cryolytic allografts implanted heterotopically (im) or in fibular osteotomy sites was assessed in rats entrained in a 12/12 hour light cycle (photoperiod = 0800-2000 hr): heterotopic grafting was performed at intervals of 4 hours within a 24-hour period, and the animals were sacrificed 3-4 weeks after grafting. Interstitial chondrification (induction) in the vascular spaces of heterotopic decalcified bone allograft matrix was significantly greater in implants performed during the day (0800-1600 hr). This response (85Sr-retention, histiometry) was heightened in animals treated with cortisone at 1600-2000 hours, suggesting that the inductive rhythms may be associated with circadian fluctuations in the immune responsivity of the host animals to antigenic challenge. Bony union was more prevalent in osteotomy implants made at 0400-0600 hour (night) than at 1600-1800 hr (day), irrespective of graft type. The incidence of clinical non-union was 50-60 per cent greater during the day when autologous or surface decalcified allograft bone was used, and about 25 per cent greater during the day with fresh allograft bone. The differences in implant success may relate to the circadian shifts in the relative size of the pool of progenitor cells in the connective tissue bed surrounding the graft at the time of transplant surgery, and to the ability of trauma to act as an osteogenic stimulus.
Explore the source record for details and available documents.
A procedure for differential staining of decalcified bone with silver nitrate showed major histological features which appeared to correspond closely to microradiographic images. The extent to which this is actually the case was investigated directly by preparing microradiographs of ground sections of baboon and dog radii and then decalcifying and staining the same sections. The many detailed similarities indicate that this staining procedure is a useful adjunct to microradiography. Thus, poorly mineralized osteons or layers of circumferential lamellae are darker stained by silver nitrate, and the variably mineralized layers of circumferential lamellae are closely duplicated by light and dark bands in the stained sections. These similarities imply that there is a relationship between the mineral density of bone and some condition of the organic matrix which is probably related to maturation changes in the collagen.
Explore the source record for details and available documents.
Experiments in rabbits were conducted to test the clinical propositions that a) the risk of nonunion in certain long bone fractures can be sharply reduced by open reduction and internal fixation, and b) that there is an optimum critical period following trauma in which this procedure should be carried out to facilitate healing. Bilateral standard open fractures of rabbit radii were internally fixed by intramedullary K-wires immediately or at 5, 10, and 17 days after trauma. These bones were subjected to stress and histometric analyses at 4-56 days after the initial fractures. The observations suggested that the pace of fracture healing could be optimized by time-delay surgery. The most exuberant and strongest calluses developed when the bones were fixed 10 days after fracture, and the rate of healing was improved. Delay times of 5 or 17 days did not provide better healing than that achieved by an immediate operation. Callus quality, in terms of the proportion of fiber bone, lamellar bone, and cartilage, was similar in all groups. The tensile strengths of the bones during callus formation were highly correlated with the ratio of callus/cortical bone areas (p less than 0.01).
The effects of stress due to brief (4--5 min) ether and pentobarbital anesthesia vs. decapitation on assays of seven enzymes in homogenates of synovium, articular and epiphyseal cartilage, and metaphyseal and cortical bone were compared. Etherization caused twofold changes in synovial and articular cartilage G-6-PDH, LDH, CPK, glutamic DH, and ICDH based on tissue dry weight and DNA content. Pentobarbital anesthesia produced only slightly lower activities, per gram DNA, of LDH, acid phosphatase, and glutamic-DH in cortical bone. Epiphyseal cartilage metabolism was unaffected by either mode of anesthesia. No difference could be detected between levels of enzyme activities of the several tissues taken from rats that had been decapitated or anesthetized with pentobarbital. The changes in enzyme activities suggested that pentobarbital was non-stressful and appropriate to metabolic studies in the skeleton.
The osteoinductive capacities of bone-marrow autografts, washed marrow-free bone allografts, and composite grafts of washed allogeneic bone impregnated with viable or killed autologous marrow cells have been compared in a heterotopic site in rabbits. Composite grafts (similar to 40 mg allogeneic bone) with viable marrow performed equally well as autografts, providing that these implants contained at least 50,000 marrow cells. Composite grafts with dead marrow were noninductive, and grafts with 10,000 viable marrow cells produced much less new bone than grafts with 50,000 cells. Postoperative treatment of host rabbits with PHA-P increased the osteoinductive capacity of composite grafts with initially subcritical numbers of marrow cells to control levels. These results indicate that the osteoinductive cells in composite grafts are mobilized from the marrow elements rather than from the undifferentiated cells in the host bed.
The bones of adult rats became progressively osteopenic 1 to 5 weeks following jejunoileal bypass or resection. These changes were accompanied by increased levels of metaphyseal enzyme activities as well as by loss of histochemically identifiable osteoid. Osteoid tissue and the ability to mineralize skeletal collagen were recovered more rapidly and fully in the resection group than in the bypass group. Metaphyseal alkaline phosphatase concentrations increased in both groups coincident with the elevated lysosomal enzymes levels, and the skeletons showed a calcium deficit (low Ca/HOPr ratio) within the first 3 weeks. In resected rats the osteopenia and bone blood chemistry were consistent with hyperparathyroidism secondary to impared Ca absorption. In bypassed rats the results suggest that the osteopenia might be related to the release of a "resorptive factor" from the excluded intestinal segment.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.