Effect of tray space on the accuracy of monophasic polyvinylsiloxane impressions.

The effect of tray space on the dimensional accuracy and stability of impressions made from four brands of monophasic polyvinyl siloxane material was assessed on the recovered stone casts by quantitative and qualitative methods. In general, both evaluation methods agreed that tray space and repeat pour did not affect the accuracy of the dies for individual castings. But disagreement was observed in the findings for fixed partial dentures (FPDs). Quantitative measurement of the interpreparation (IP) dimensions did suggest the possibility of a potential problem when a FPD is cast in one piece because of a significantly reduced distance between the two abutments. However, from the findings of this study it can be concluded that a rigid stock tray can be used with a monophasic polyvinyl siloxane impression material.     

Mammalian wound repair environment does not permit skeletal muscle regeneration

Repair and regeneration are mutually exclusive responses to injury. Previous studies have shown that wound fluids promote proliferation, but not differentiation, of myoblasts in vitro. This study explored the ability of the repair environment within polyvinyl alcohol sponges to support cellular events of skeletal muscle regeneration in vivo. Neonatal rat L8 myoblasts were modified to express beta-galactosidase then inoculated into plain sponges or sponges containing minced muscle. Labeled myoblasts were found in myotubes within minced muscle. In contrast, myoblasts inoculated into sponges lacking muscle remained mononucleate. Occurrence of labeled myoblasts within myotubes, which required fusion, represents differentiation of inoculated myoblasts to participate in regeneration. Failure of myoblasts to form myotubes in sponges lacking muscle suggests that this wound repair environment cannot support morphologic differentiation of myoblasts. Although this repair environment can support the survival of myoblasts, it did not support myogenesis, an event necessary to complete skeletal muscle regeneration. Data from this study reinforce earlier studies in vitro and suggest that the properties attributed to wound fluids are inherent in the wound environment. Whether the inability of this environment to support myogenesis is the consequence of the absence of essential factors or the presence of inhibitors remains to be determined.     

Effect of photodynamic therapy on blood flow in normal and tumor vessels

The aim of this series of experiments was to determine the dynamic blood flow changes that occur in normal and neoplastic tissues during photodynamic therapy. Mice bearing SMT-F tumors and rats with transplanted chondrosarcomas were injected with graded doses of dihematoporphyrin ether. Studies of changes in single-vessel and whole-tumor blood flow were carried out with 630 nm light activation. A helium neon laser Doppler velocimeter was used to stimulate dihematoporphyrin ether, as well as to measure changes in flow velocity in both single-vessel and whole-tumor models. There was a reduction of flow velocity in all vessels and tumors in animals injected with 1 to 40 mg/kg dihematoporphyrin ether intraperitoneally. The extent of flow reduction was related to drug dose administered. Decreases in blood flow began within 10 seconds of light stimulation and were maximal within 5 minutes. Both normal and tumor vessels responded similarly. We conclude that photodynamic therapy leads to significant microcirculatory changes that may be pertinent to the mechanism of tumor necrosis.     

Congenital absence of the inferior rectus muscle--diagnosis and management.

BACKGROUND: Congenital absence of the inferior rectus muscle is a rare cause of apparent inferior rectus palsy especially in the absence of associated cranial facial anomalies. METHODS: We report three cases of isolated congenital absence of the inferior rectus muscle and its successful surgical management. RESULTS: Failure of the normal embryologic development of the mesodermal complex around the eye can lead to agenesis of the extraocular muscles. In apparent palsies of the inferior rectus muscle and no definite cause, a high index of suspicion and orbital imaging can confirm the diagnosis of congenitally absent inferior rectus preoperatively. Surgical correction may involve inferior transposition of the horizontal rectus muscles. CONCLUSIONS: Although rare, congenital absence of the inferior rectus muscle is a possible cause of apparent inferior rectus muscle palsy particularly in the absence of another identifiable cause. Strabismus surgery in conjunction with intramuscular botulinum toxin injection can offer significant improvement in function and cosmesis of these patients.     

A comparison of coarctation resection and subclavian flap angioplasty using ultrasonographically monitored postocclusive reactive hyperemia

The reported relatively high incidence of early restenosis at the coarctation repair site with subclavian flap angioplasty, especially in infants less than 3 months of age, prompted a physiologically oriented analysis of relief of obstruction from coarctation after subclavian flap angioplasty versus resection and end-to-end anastomosis in infancy. Twenty-one patients who had undergone repair of coarctation in infancy by either subclavian flap angioplasty (nine patients) (median age 8 years) or resection and end-to-end anastomosis (12 patients) (median age 8 years) were evaluated by Doppler spectrum analysis of the blood flow velocities in the femoral artery at rest and during reactive hyperemia. The median resting right upper to lower limb systolic pressure difference (with interquartile range) was similar in the angioplasty, resection and anastomosis, and control groups: -5 mm Hg (18 mm Hg), 0 mm Hg (12 mm Hg), and -2.5 mm Hg (10 mm Hg), respectively. Also, similar resting values for the maximum frequency of the advancing curve and the pulsatility and resistance indices were measured in the three groups. During reactive hyperemia of the leg, however, a significant hemodynamic obstruction across the repair site became clinically manifest in the angioplasty group only, as documented by a lower pulsatility index in comparison with the control group (p = 0.01, Mann-Whitney U test). Comparison of the hemodynamic results between the angioplasty and resection and anastomosis groups in subdivisions of infants operated on at an age of less or greater than 3 months, both at rest and during reactive hyperemia, showed, already at rest, a significantly lower value for the pulsatility index in the former angioplasty subdivision (p = 0.05, Student's t test), indicating a significant resistance at the coarctation repair site in the angioplasty patients operated on before the third month of life. A disadvantage of angioplasty (compared with resection and anastomosis) was noted when angioplasty was performed before the third month of life, and an unequivocal lack of advantage was noted when performed beyond that period regarding relief of obstruction from coarctation. In addition, a definite potential for adverse long-term effects on the hemodynamics of the left upper limb after subclavian flap angioplasty in infancy has been documented. For these reasons we prefer to perform resection and end-to-end anastomosis for repair of coarctation in infancy.     

Chronic hepatitis B virus infection in patients with “Normal” ALT levels

Not many data exist to guide us in the management of patients with chronic hepatitis B virus infection and “normal” alanine aminotransferase levels. Many of these patients may not have normal levels on long-term follow-up or when the upper limit of normal is determined from a truly healthy reference population. These patients may have significant histologic disease and benefit from further investigation or treatment. This article focuses on the disease course of such patients.     

Rapid evaluation of tetanus immunity by a haemagglutination test in the injured at a hospital emergency unit

A turkey red blood cell haemagglutination assay (TRBC HA) allowing rapid measurement of the antibodies against tetanus has been set recently. Its feasibility was evaluated in injured patients admitted into an emergency unit during summer 1987. TRBC HA was performed by the same physician who questioned the patient on his/her previous vaccinations and evaluated his/her immunization status. The rapid HA test practiced in emergency was controlled by TRBC HA and ELISA measurement of antibodies carried out in the laboratory. Each method was compared to the others: the results were fitted and no significant difference was found. The preventive procedures which would have followed the antibody measurement by immediate TRBC HA were compared to the decision resulting from clinical evaluation. The immunoprophylactic attitude would have been the same in 82% of cases. TRBC HA is a reliable test, and feasible in an emergency: it could help in making the appropriate decision for immunoprophylaxis to be applied to the injured and other patients at risk of tetanus.     

Prevalent vertebral deformities: Relationship to bone mineral density and spinal osteophytosis in elderly men and women

The aims of this study were to ascertain vertebral deformity prevalence in elderly men and women and to describe the association between bone mineral density (BMD) at the lumbar spine and femoral neck, severity of spinal degenerative disease and vertebral deformity prevalence. We performed standardized spinal radiographs in a random sample of 300 elderly men and women participating in the Dubbo Osteoporosis Epidemiology Study, a population-based study of fracture risk factors. Radiographs were read independently by masked observers for the prevalence of vertebral deformity and severity of osteophytosis. BMD was measured by dual-energy X-ray absorptiometry. The prevalence of vertebral deformities was critically dependent on the criterion used. The less strict criteria seemed to overestimate deformities at either end of the spine region analysed. However, irrespective of the criterion used, prevalence of deformity was higher in men than in women (25% vs 20% for the 3 SD criterion, 17% vs 12% for the 4 SD criterion and 27% vs 25% for the 25% criterion). Femoral neck BMD was more strongly associated with vertebral deformities than spinal BMD for the 25% criterion (OR/SD change in BMD 1.39 (p=0.02) vs 1.20 (p=0.19)), 3 SD criterion (OR/SD change in BMD 1.45 (p=0.01) vs 1.10 (p=0.34)) and 4 SD criterion (OR/SD change in BMD 1.98 (p=0.0002) vs 1.68 (p=0.008)). BMD was also more strongly associated with biconcave deformities than either wedge or crush deformities and more so in men than in women. Severity of spinal osteophytosis was not associated with vertebral deformity. In conclusion, femoral neck BMD is at least equivalent to the lumbar spine BMD in strength of association with prevalent vertebral fractures. Spinal osteophytosis falsely elevates BMD without a concomitant decrease in fracture risk, indicating that any interpretation of spinal BMD needs to be adjusted for osteophytosis. These findings support the use of femoral neck bone densitometry in older men and women. Moreover, these data indicate that current criteria for radiological assessment of vertebral deformity are sufficiently loose to include a substantial proportion of non-fractures in the elderly, with important implications for the design of clinical trials. However, irrespective of the criterion used, vertebral deformities in men are at least as common, if not more so, than in women, suggesting that vertebral osteoporotic fractures are overlooked in men.