Mechanical assessment of effects of grape seed proanthocyanidins extract on tibial bone diaphysis in rats

We studied the effects of grape seed proanthocyanidins extract (GSPE) given as a ratio of 3 mg in 100 g in a standard diet, on the tibial bone diaphysis in low-calcium fed rats. Measurements of bone density, mineral content, geometry, and bone strength using peripheral quantitative computed tomography (pQCT). Further, the whole tibia bones were tested for mechanical resistance using a material-testing machine, and mineral elements were also determined. Forty male Wistar rats, 5 weeks old, were divided into control (Co), low-calcium diet (LC), low-calcium diet . standard diet (LCS), and low-calcium diet . standard diet with supplementary GSPE (LCSG) groups. We found no significant differences in body weight among the 4 groups, whereas all of the bone parameters in LC were significantly lower than those in Co (p<0.01, except in periosteal perimeter (Peri) p<0.05). The cortical bone mineral content (CtBMC), cortical bone density (CtvBMD) and Peri in LCSG were significantly higher than those in LCS (p<0.01; p<0.01; p<0.05, respectively). All bone parameters in LCSG were significantly higher than those in LC (p<0.01, except in Peri, and stress strain index to reference axis x (xSSI) p<0.05)). In addition, Ca, P, and Zn contents in LCSG were significantly higher than those in LCS (p<0.01; p<0.01; p<0.05, respectively). Our results suggest that GSPE included in a diet mixture with calcium has a beneficial effect on bone formation and bone strength for the treatment of bone debility caused by a low level of calcium.     

Histomorphometric and electron microscopic analyses of tibial epiphyseal plates from Cosmos 1887 rats

Previous studies have shown that the changes seen in the bones of growing rats exposed to microgravity are due in part to changes that occur in the growth plate during spaceflight. In this study, growth plates of rats flown aboard Cosmos 1887 (12.5-day flight plus 53.5-h recovery at 1 g) were analyzed using light and electron microscopy and computerized planimetry. The proliferative zone of flight animals was found to be significantly (P less than or equal to 0.01) larger than that of controls, while the reserve and hypertrophic/calcification zones were significantly reduced. Flight animals also had more cells per column in the proliferative zone than did controls and less in the hypertrophic/calcification region. The total number of cells, however, was significantly greater in flight animals. No difference was found in perimeter or in shape factor, but area was significantly less in flight animals. Electron microscopy showed that collagen fibrils in flight animals were wider than in controls. Since the time required for a cell to cycle through the growth plate is 2-3 days at 1 g, the results reported here represent both the effects of exposure to microgravity and the initial stages of recovery from that exposure.     

Bone size and mechanics at the femoral diaphysis across age and sex

The reasons for the increase in fracture rates with age are not fully understood. It is known that there is a decrease in bone mass with a presumed loss of strength. This decrease may possibly be compensated for by changes in cross-sectional geometry. Previous studies, which have been limited by lack of information on subjects’ heights and weights, were not able to resolve this issue. In this study, measurements of cross-sectional geometry (area and second moments of area) from 107 specimens of human femoral diaphysis from subjects aged 21–92 years were analysed. Mathematical models of the variation in bone geometry with age were developed. These models included the effects of sex, height and weight. Values of parameters from these models were then used in a biomechanical analysis of the static stresses at the mid-shaft of the femur. Results indicate that although there was a reduction in cortical area in old age, bone tissue was redistributed so that neither bending stresses in the coronal plane nor torsional stresses were higher in old age than in young adulthood. An additional finding was that at any age women had smaller bones, less cortical bone area and higher bone stresses than men. This finding may have some bearing on the higher fracture incidence seen in older women.     

Parathyroid hormone rapidly stimulates hyaluronan synthesis by periosteal osteoblasts in the tibial diaphysis of the growing rat

Short term treatment (3-24 h) with parathyroid hormone (PTH) stimulated the synthesis and accumulation of hyaluronan (HyA) in explant cultures of tibial diaphyses from young rats. PTH increased the overall HyA content of periosteum 5-fold, with the basal cambium layer exhibiting the greatest enhancement ( approximately 8-fold). PTH increased the HyA content of cortical bone by 2-fold while not affecting the HyA content of bone marrow. PTH treatment greatly enhanced HyA staining throughout all layers of the periosteum, although its most dramatic effect occurred in the basal cambium layer. Here, unlike in the control tissue sections, nearly all cambium-lining osteoblasts stained intensely positive for HyA. PTH treatment enhanced the HyA staining of osteocytes in cortical bone tissue sections to the extent that the lacunocanalicular system became visualized. Three significant findings were revealed in this study. First, mature periosteal osteoblasts, under natural conditions, do not contain much HyA in their surrounding extracellular matrix but dramatically enhance their matrix HyA content when treated with PTH. Second, pre-osteocytes and osteocytes contain more HyA in their natural matrix than mature lining osteoblasts, and they appear to have functional PTH receptors because they responded to PTH treatment with an enhancement of HyA content. Finally, it was observed that the lining cells along the endosteal surface of the diaphysis did not stain strongly positive for HyA either naturally or when exposed to PTH treatment. This indicates that periosteal and endosteal osteoblastic cell populations exhibit metabolic differences in their extracellular matrix responses to PTH.     

Changes in hemodynamics of tibial diaphysis in case of blood flow disorder in superficial femoral artery

Changes in tibial hemodynamics have been studied experimentally after applying a clamp (n=41) and resection of superficial femoral artery (n=22) in 63 adult dogs. It has been revealed with the help ofrheovasography that, in case of blood flow disorders in the superficial femoral artery, anastomoses with deep femoral artery branches contribute to maintenance of blood circulation in tibia, and in this connection the parameters of tibial blood flow may significantly differe from those of circulation in the leg soft tissues. Preservation of intraosseous pressure all along tibial diaphyseal cavity demonstrates a possibility of using its driving force to compensate for the circulatory insufficiency in the leg soft tissues and, moreover, in that part of the bone the environment of which in ischemia is involved.     

Healing of "wire tunnels" in tibial diaphysis: data of local X-ray study and densitometry

Fifteen pelvic extremities from adult dogs were used to perform 60 cross tunnelization of tibial diaphysis with a wire having a pointed groove, 1.8-mm in diameter, at 1,500 rpm. Thirty five leg X-ray films in the lateral projection, which show changes on days 30, 60, 90, 120, 520 after the experiment, were studied. Bony diaphysis tunnelization was found to give rise to a regeneration focus wherein an area of tissue element degradation and an area of introduction of bony fragments into soft tissues were detectable. Changes in the regeneration focus were determined by a response to osseous fragments, which involved the formation of an bony regenerate during a month and to the resorption of the bony matter of an osseous regenerate and osseous fragments in future. Healing of diaphysis defects began with the resorption of a damaged cortical layer. Osteogenesis prevailed at month 2 and ensured healing of cortical layer defects following 4-6 months.     

Microcirculatory bed and the structure of the compact substance of the cat tibial diaphysis normally and after multiple exposure to G loads]

Blood bed and structure of the compact substance of the cat tibial diaphysis have been studied at normal conditions and after repeated effect of gravitational overloadings. Hypergravitation produced a noticeable rearrangement in the microcirculatory bed and in histoarchitectonics of the bone compact substance. The date obtained demonstrate that the changes produced depend on the number of parameters participating in the gravitational effect and on the position of the animal in the container, as well as on the time when the animal falls ill after the experiment.     

Noninvasive assessment of vascular function in the posterior tibial artery of healthy humans

Flow-mediated dilation (FMD) measures the ability of an artery to relax in response to increases in blood velocity. FMD, primarily of the brachial artery, has been used as a noninvasive method of assessing vascular health. The purpose of this study was to assess FMD in the lower legs of humans. Six healthy subjects (27 PlusMinus; 6 yrs) were tested. Doppler ultrasound images of the posterior tibial artery were taken before, during, and after 5 minutes of proximal cuff occlusion. FMD was measured as the percent increase in diameter after cuff release. Vascular tone was calculated using the resting diameter as a percentage of the vessel's vasoactive range. Minimum diameter occurred during ischemia and maximal diameter occurred following reactive hyperemia with local heating. The lower leg was heated with 10 minutes of immersion in 44 degrees C water. Mean diameters at rest, cuff, and during release were 0.267 PlusMinus; 0.062, 0.162 PlusMinus; 0.036, 0.302 PlusMinus; 0.058 cm, respectively. FMD was 13.5 PlusMinus; 6.6 % and vascular tone was 29 PlusMinus; 16.3%. We also found that retesting on a second day produced mean diameter values within 8% of the first day. Larger resting diameter (decreased tone) correlated with decreased FMD (r2 = 0.73). These results suggest that FMD and vascular tone can be measured in the posterior tibial artery. This is a potentially powerful tool to non-invasively measure vascular health in the lower legs of people at risk for vascular disease.     

Histomorphometric analysis of fibrosis in the renal interstitial compartment

The interstitium is the extravascular intertubular space of the renal parenchyma, which provides structural support to the functional renal units and is included at the same time in nearly all renal functions. Alterations to this renal compartment have been found in almost all glomerular diseases. During the last thirty years the studies of a few groups of investigators have shown that the degree of the renal dysfunction is strongly correlated with the changes in the tubulointerstitial compartment. We made a morphometric study of a group of 10 renal biopsies, previously diagnosed as IgA nephropathy or membranoproliferative glomerulonephritis. For morphometric analysis we made colour extraction of the interstitial area on tissue sections stained with trichrom Masson using the LUCIA M-NIKON image analysing system with integrated software for statistical analysis of the data. We measured the surface of the marked fields and the results were expressed as a percentage of the total scanned area. The results were correlated with the serum creatinine at the time of biopsy. We found fibrosis occupying more than 10% of the tubulointerstitial surface in all 10 patients. Six of them had a moderate level of fibrosis, occupying more that 20% of the tubulointerstitial space. The statistical analysis of these results showed a significant correlation between the degree of the interstitial expansion and the serum creatinine. The results showing the correlation between these parameters will enable the quantitative histological analyses to be included in the process of the nephropathological diagnosis in order to evaluate the histological risk factors in glomerular diseases.     

Two hominin incisor teeth from the middle Pleistocene site of Boxgrove, Sussex, England

In 1995-1996 two isolated hominin lower incisors were found at the middle Pleistocene site of Boxgrove in England, with Lower Palaeolithic archaeology. Boxgrove 2 is a permanent lower right central incisor and Boxgrove 3 a permanent lower left lateral incisor. They were found separately, but close to one another and appear to belong to the same individual. The Boxgrove 1 tibia discovered in 1993 came from a different stratigraphic context and is thus believed to represent a different individual. This paper describes the morphology of the incisors, which is similar to other middle Pleistocene hominin specimens and, as with the tibia, suggests that they could be assigned to Homo heidelbergensis (recognising that the taxonomic status of this species is still a matter of debate). The incisors show substantial attrition associated with secondary dentine deposition in the pulp chamber and clearly represent an adult. They also show extensive patterns of non-masticatory scratches on the labial surfaces of both crown and root, including some marks which may have been made postmortem. The roots were exposed in life on their labial sides by a large dehiscence, extending almost to the root apex. This is demonstrated by deposits of calculus, polishing, and scratching on the exposed surfaces. The dehiscence may have been caused by repeated trauma to the gingivae or remodelling of the tooth-supporting tissues in response to large forces applied to the front of the dentition.