Estrogen regulates the rate of bone turnover but bone balance in ovariectomized rats is modulated by prevailing mechanical strain

Estrogen deficiency induced bone loss is associated with increased bone turnover in rats and humans. The respective roles of increased bone turnover and altered balance between bone formation and bone resorption in mediating estrogen deficiency-induced cancellous bone loss was investigated in ovariectomized rats. Ovariectomy resulted in increased bone turnover in the distal femur. However, cancellous bone was preferentially lost in the metaphysis, a site that normally experiences low strain energy. No bone loss was observed in the epiphysis, a site experiencing higher strain energy. The role of mechanical strain in maintaining bone balance was investigated by altering the strain history. Mechanical strain was increased and decreased in long bones of ovariectomized rats by treadmill exercise and functional unloading, respectively. Functional unloading was achieved during orbital spaceflight and following unilateral sciatic neurotomy. Increasing mechanical loading reduced bone loss in the metaphysis. In contrast, decreasing loading accentuated bone loss in the metaphysis and resulted in bone loss in the epiphysis. Finally, administration of estrogen to ovariectomized rats reduced bone loss in the unloaded and prevented loss in the loaded limb following unilateral sciatic neurotomy in part by reducing indices of bone turnover. These results suggest that estrogen regulates the rate of bone turnover, but the overall balance between bone formation and bone resorption is influenced by prevailing levels of mechanical strain.     

The dental care of the psychiatric patient

The dental care of the psychiatric patient requies careful observatio and history taking. Medications used in the treatment of psychiatric illnesses demand care in treatment planning and prescibing. The nature and sequellae of many psychiatric conditions have a direct bearing on the clinical picture presented by the patient and the success of dental care. Implementation of care must have a significant component of flexibility in terms of treatment outcomes and the time and method of providing treatment. Particular emphasis must be placed uppon the establishment of effective oral hygiene programmes. The psychiatric patient suffers not only from a socially debilitating disease but also from society's opprobrium. With a modicum of effort, the dental profession can rise above that.     

Administration of 9-[2-(phosphonomethoxy)propyl]adenine (PMPA) for prevention of perinatal simian immunodeficiency virus infection in rhesus macaques

Simian immunodeficiency virus (SIV) infection of newborn macaques is a useful animal model to explore novel strategies to reduce perinatal human immunodeficiency virus (HIV) infection. The availability of two easily distinguishable virus isolates, SIVmac251 and the simian/human immunodeficiency virus chimera SHIV-SF33, allows tracing the source of infection following inoculation with both viruses by different routes. In the present study, we evaluated the efficacy of pre- and postinoculation treatment regimens with 9-[2-(phosphonomethoxy)propyl]adenine (PMPA) to protect newborn macaques against simultaneous oral SIVmac251 and intravenous SHIV-SF33 inoculation. Untreated newborns became persistently infected following virus inoculation. When three pregnant macaques were given a single subcutaneous dose of PMPA 2 hr before cesarean section, their newborns became SIV-infected following SIV and SHIV inoculation shortly after birth. In contrast, when four newborn macaques were inoculated simultaneously with SIV and SHIV, and started immediately on PMPA treatment for 2 weeks, only one animal became persistently SIV-infected; the remaining three PMPA-treated newborns, however, had some evidence of an initial transient virus infection but were seronegative and healthy at 8 months of age. Our data demonstrate that PMPA treatment can reduce perinatal SIV infection and suggest that similar strategies may also be effective against HIV.     

Influence of finishing time on marginal sealing ability of new generation composite bonding systems

Although variation in finishing techniques has been shown to affect microleakage, little research has been published on the influence of finishing time on the marginal sealing ability of new generation composite bonding systems. The objective of the present study was to evaluate the influence of finishing time on the enamel and dentine marginal sealing ability of four new generation composite systems. Two class V preparations, which were solely in enamel or dentine, were made on the buccal surfaces of 96 freshly extracted molar teeth. The teeth were randomly divided into four groups of 24 and restored with composite resin (Silux Plus) utilizing the following bonding systems: Scotchbond Multi-purpose, Fuji Bond LC, Prime & Bond 2.0 and Bisco One-step. Half of the restorations in each group were finished immediately after light polymerization and stored for 1 week. For the remaining restorations, finishing was delayed for 1 week. The storage medium was isotonic saline at 37 degrees C throughout the experiment. All restorations were then thermocycled, subjected to dye penetration testing, sectioned and scored. The results suggest that the finishing of composite restorations, bonded with the bonding systems evaluated, should be carried out immediately after light polymerization. Delayed finishing does not improve but instead can be detrimental to the marginal seal of the restorations. The effects of delayed finishing are, however, both bonding system and tissue specific.     

Pathogenesis of early operative site infections after orthotopic liver transplantation

BACKGROUND: We hypothesized that operative site infections after orthotopic liver transplantation arise from bacteria in bile or jejunum. METHODS: To ascertain the validity of this hypothesis and to assess the effect of systemic antibiotic prophylaxis, we obtained intraoperative cultures of peritoneum, fascia, explant and donor liver bile, and jejunal lumen in 77 liver transplantations, and we monitored outcome. RESULTS: Pathogens were recovered from peritoneum, fascia, or bile in 11 cases. By univariate analysis, a positive culture was significantly associated with choledochojejunostomy (P=0.0002), previous liver transplantation (P=0.0002), and previous hepatobiliary surgery (P=0.002). Operative site infections during the first 2 weeks after transplantation occurred only in cases with positive intraoperative cultures, and three of the four infections were caused by the same bacteria detected intraoperatively. Antibiotic susceptibility of intraoperative isolates was tested in nine cases; infection occurred in two of three cases in which the isolates were resistant to the systemic antibiotic prophylaxis and in none of six cases with susceptible isolates. CONCLUSIONS: Our findings suggest that systemic antibiotic prophylaxis for more than 2 days may be beneficial in cases with bacterial contamination of the operative site but may not be necessary in other cases.     

Psychogeriatrics in South-East Asia

A common phenomenon in South-East Asia is ageing of the population. This article describes the various stages of development of psychogeriatrics in Hong Kong, Singapore, Malaysia, Thailand, Indonesia and the Philippines. It is only in the last few years that more systematic development of psychogeriatric services has begun under the pressure of an ageing population. The model of service delivery in Hong Kong can serve as an example of development of psychogeriatric services in South-East Asia.