Development and calibration of a load sensing cervical distractor capable of withstanding autoclave sterilization

In surgery of the cervical spine, a Caspar pin distractor is often used to apply a tensile load to the spine in order to open up the disc space. This is often done in order to place a graft or other interbody fusion device in the spine. Ideally a tight interference fit is achieved. If the spine is over distracted, allowing for a large graft, there is an increased risk of subsidence into the endplate. If there is too little distraction, there is an increased risk of graft dislodgement or pseudoarthrosis. Generally, graft height is selected from preoperative measurements and observed distraction without knowing the intraoperative compressive load. This device was designed to give the surgeon an assessment of this applied load. Instrumentation of the device involved the application of strain gauges and the selection of materials that would survive standard autoclave sterilization. The device was calibrated, sterilized and once again calibrated to demonstrate its suitability for surgical use. Results demonstrate excellent linearity in the calibration, and no difference was detected in the pre- and post-sterilization calibrations.

A new method to investigate in vivo knee behavior using a finite element model of the lower limb

Several finite element models have been developed for estimating the mechanical response of joint internal structures, where direct or indirect in vivo measurement is difficult or impossible. The quality of the predictions made by those models is largely dependent on the quality of the experimental data (e.g. load/displacement) used to drive them. Also numerical problems have been described in the literature when using implicit finite element techniques to simulate problems that involve contacts and large displacements. In this study, a unique strategy was developed combining high accuracy in vivo three-dimensional kinematics and a lower limb finite element model based on explicit finite element techniques. The method presents an analytical technique applied to a dynamic loading condition (impact during hopping on one leg). The validation of the lower limb model focused on the response of the whole model and the knee joint in particular to the imposed 3D femoral in vivo kinematics and ground reaction forces. The approach outlined in this study introduces a generic tool for the study of in vivo knee joint behavior.

Separate vertical wiring for the fixation of comminuted fractures of the inferior pole of the patella

Comminuted and displaced fractures of the inferiorole of the patella are not easy to reduce and it is difficult to fix the fragments soundly enough to allow early movement of the knee. We have evaluated the clinical effectiveness of the separate vertical wiring technique in acute comminuted fractures of the inferior pole of the patella. A biomechanical study was also performed using ten pairs of embalmed cadaver knees. A four-part fracture was made on the inferior pole of the patella and fixed by two separate vertical wires on one side and two pull-out sutures after partial patellectomy on the other. The ultimate load to failure in the first group was significantly higher than in the second (250.1+/- 109.7 N v 69.7 +/- 18.9 N, p < 0.002), as was the stiffness (279.9 +/- 76.4 N/mm v 23.2 +/- 11.4 N/mm, p < 0.001). The separate wire technique was used in 25 patients with comminuted fractures of the inferior pole of the patella who were followed up for a mean period of 22 months (10 to 50). All the fractures healed at a mean of seven weeks (6 to 10). No breakage of a wire or infection occurred. The mean grading at the final follow-up was 29.5 points (27 to 30) using the Böstman method. This technique preserved the length of the patella, fixed the comminuted fragments of the inferior pole and avoided long-term immobilisation of the knee.

Lower extremity injuries in lateral impact: a retrospective study

ABSTRACT A retrospective analysis of the NASS/CDS database from 1993 to 2000 was used to investigate lower extremity injury in lateral impact. The analysis includes the study of the injury patterns, crash characteristics and the interactions between the occupant and the vehicle interior, including injuries to the farside occupants. The findings include significantly different injury patterns for the nearside and farside impacts. In particular, while the proportion of pelvis/hip injuries, with respect to AIS2 and AIS3 lower extremity skeletal injuries and 2-4 and 10-8 o'clock side impacts, was higher in nearside (70.4%) than farside (38.3%), the opposite trend was observed for the thigh (2.8% vs 4.5%), knee (6.2% vs 16.7%), leg (10.1% vs 19.5%) and foot/ankle (5.6% vs 14.7) injuries. Analysis of the PDOF suggested that a large proportion the impacts occurred obliquely, at approximately 10 and 2 o'clock, with a rearward component of force. It is hoped that the findings of the current study can help to investigate injury mechanisms.

Salivary cystatins influence ingestion of capsaicin-containing diets in the rat

Dietary capsaicin consumed by rats over several days induces cystatin-like substances in submandibular saliva. Yet the physiological role of these salivary proteins has not been thoroughly investigated. Salivary cystatins in the rat submandibular glands are known to be induced by chronic treatment with the sympathetic beta-agonist, isoproterenol. In the present study, the possible roles of the salivary proteins on food intake were examined by comparing consumption of a capsaicin-adulterated (0.05%) diet in rats with and without isoproterenol pretreatment (0.1 and 5.0 mg/kg, 5 days). Electrophoretic analysis performed prior to feeding trials revealed that the group pretreated with 5 mg/kg isoproterenol had large amounts of cystatin in the saliva compared with the group pretreated with 0.1 mg/kg isoproterenol and control group. The group treated with 5 mg/kg isoproterenol showed greater consumption of the capsaicin-adulterated diet than the other groups until the 3rd day of trials. Bilateral removal of the submandibular and sublingual glands neutralized the effects of isoproterenol. Induction of salivary cystatins by isoproterenol treatment was not mimicked by systemic and intragastric administration of capsaicin. These results suggest that cystatins are included in the salivary proteins induced by capsaicin and that they contribute to enhanced ingestion of the capsaicin diet. Induction of salivary cystatins may be triggered by irritation of the oral mucosa by capsaicin.

Qi therapy as an intervention to reduce chronic pain and to enhance mood in elderly subjects: a pilot study

Qi therapy (or external Qi) is an oriental complementary therapy preventing, curing disease and strengthens health and improving the human potentiality through regulation of body. It is increasingly being used to improve the quality of life, but there is little direct evidence of its efficacy. This study assessed the effects of Qi therapy (QT) on reducing pain and enhancing mood states in elderly subjects with chronic pain. We studied 40 elderly participants with chronic pain, who were randomly allocated to receive QT (n=20) or standard care (n=20). The experimental group receives Qi therapy twice a week for 2 weeks (total 4 times), and control group received general care at the same time and the same amount of duration. We measured pain level and Profile of Mood State (POMS) to explore participants' response to Qi therapy. There was a significant reduction in pain (p<0.0001) after QT and an improved positive mood state (p<0.0001). These findings suggest that Qi therapy may have a role in helping the elderly to cope with their pain and mood disturbances.

Recent advances in brain injury research: a new human head model development and validation

Many finite element models have been developed by several research groups in order to achieve a better understanding of brain injury. Due to the lack of experimental data, validation of these models has generally been limited. Consequently, applying these models to investigate brain responses has also been limited. Over the last several years, several versions of the Wayne State University brain injury model (WSUBIM) were developed. However, none of these models is capable of simulating indirect impacts with an angular acceleration higher than 8,000 rad/s(2). Additionally, the density and quality of the mesh in the regions of interest are not detailed and sensitive enough to accurately predict the stress/strain level associated with a wide range of impact severities. In this study, WSUBIM version 2001, capable of simulating direct and indirect impacts with a combined translational and rotational acceleration of the head up to 200 g and 12,000 rad/s(2) has been developed. This new finely meshed model, consisting of more than 314,500 elements and 281,800 nodes, also simulates an anatomically detailed facial bone model. An additional new feature of the model is the damageable material property representation of the facial bone and the skull, allowing it to simulate bony fractures. The model was subjected to extensive validation using published cadaveric test data. These data include the intracranial and ventricular pressure data reported by Nahum et al. (1977) and Trosseille et al. (1992), the relative displacement data between the brain and the skull reported by King et al. (1999) and Hardy et al. (2001), and the facial impact data reported by Nyquist et al. (1986) and Allsop et al. (1988). With the enhanced accuracy of model predictions offered by this new model, along with new experimental data, it is hoped that it will become a powerful tool to further our understanding of the mechanisms of injury and the tolerance of the brain to blunt impact.

Prodigiosin blocks T cell activation by inhibiting interleukin-2Ralpha expression and delays progression of autoimmune diabetes and collagen-induced arthritis

Prodigiosin (PDG) was previously reported to be a T cell-specific immunosuppressant. Here we describe the mechanism of action of PDG in T cells and the effect of PDG on autoimmune diseases. PDG selectively suppresses concanavalin A (Con A)-induced T cell proliferation, but has little effect on lipopolysaccharide-induced proliferation of B cells and nitric oxide production of macrophages. Although PDG does not block interleukin (IL)-2 production, it efficiently inhibits interleukin-2 receptor alpha-chain (IL-2Ralpha) expression, and this results in a disruption of the IL-2/IL-2R signaling pathway, on which a great part of the regulation of T cell activation depends. PDG blocks T cell differentiation into effector helper T cells secreting interferon-gamma and IL-4 as well as into effector cytotoxic T lymphocytes expressing perforin, which is at least in part resulting from inhibition of the IL-2/IL-2R signaling. PDG indirectly blocks signal transducer and activator of transcription activation by inhibiting cytokine signalings in Con A-activated T cells, although it does not inhibit the activation of nuclear factor-kappaB, nuclear factor of activated T cells, and activator protein-1. As direct evidence of immunosuppression in vivo, we show that PDG markedly reduced blood glucose levels and cellular infiltration into the pancreatic islets in nonobese diabetic mice, and that it also delays the onset of collagen-induced arthritis in DBA/1 mice. In conclusion, our results demonstrate that PDG has a unique mode of action, namely, that it blocks T cell activation by inhibiting primarily IL-2Ralpha expression in the IL-2/IL-2R signaling, and show that this compound represents a promising immunosuppressant candidate for the treatment of autoimmune diseases.

Development of a finite element model of the human abdomen

Currently, three-dimensional finite element models of the human body have been developed for frequently injured anatomical regions such as the brain, chest, extremities and pelvis. While a few models of the human body include the abdomen, these models have tended to oversimplify the complexity of the abdominal region. As the first step in understanding abdominal injuries via numerical methods, a 3D finite element model of a 50(th) percentile male human abdomen (WSUHAM) has been developed and validated against experimental data obtained from two sets of side impact tests and a series of frontal impact tests. The model includes a detailed representation of the liver, spleen, kidneys, spine, skin and major blood vessels. Hollow organs, such as the esophagus, stomach, small and large intestines, gallbladder, bile ducts, ureters, rectum and adrenal glands are grouped into three bodybags in order to provide realistic inertial properties and to maintain the position of the solid organs in their appropriate locations. Using direct connections, the model was joined superiorly to a partial model of the human thorax, and inferiorly to models of the human pelvis and the lower extremities that have been previously developed. Material properties for various tissues of the abdomen were derived from the literature. Data obtained in a series of cadaveric pendulum impact tests conducted at Wayne State University (WSU), a series of lateral drop tests conducted at Association Peugeot-Renault (APR) and a series of cadaveric lower abdomen frontal impact tests conducted at WSU were used to validate the model. Results predicted by the model match these experimental data for various impact speeds, impactor masses and drop heights. Further study is still needed in order to fully validate WSUHAM before it can be used to assess various impact loading conditions associated with vehicular crashes.

Investigation of Head Injury Mechanisms Using Neutral Density Technology and High-Speed Biplanar X-ray

The principal focus of this study was the measurement of relative brain motion with respect to the skull using a high-speed, biplanar x-ray system and neutral density targets (NDTs). A suspension fixture was used for testing of inverted, perfused, human cadaver heads. Each specimen was subjected to multiple tests, either struck at rest using a 152-mm-diameter padded impactor face, or stopped against an angled surface from steady-state motion. The impacts were to the frontal and occipital regions. An array of multiple NDTs was implanted in a double-column scheme of 5 and 6 targets, with 10 mm between targets in each column and 80 mm between columns. These columns were implanted in the temporoparietal and occipitoparietal regions. The impacts produced peak resultant accelerations of 10 to 150 g, and peak angular accelerations between 1000 and 8000 rad/s(2). For all but one test, the peak angular speeds ranged from 17 to 22 rad/s. The relative 3D displacements between the skull and the NDTs were analyzed. The localized motions of the brain generally followed loop or figure eight patterns, with peak displacements on the order of +/- 5 mm. These results can be used to further finite-element modeling efforts.

Lower Limb: Advanced FE Model and New Experimental Data

The Lower Limb Model for Safety (LLMS) is a finite element model of the lower limb developed mainly for safety applications. It is based on a detailed description of the lower limb anatomy derived from CT and MRI scans collected on a subject close to a 50th percentile male. The main anatomical structures from ankle to hip (excluding the hip) were all modeled with deformable elements. The modeling of the foot and ankle region was based on a previous model Beillas et al. (1999) that has been modified. The global validation of the LLMS focused on the response of the isolated lower leg to axial loading, the response of the isolated knee to frontal and lateral impact, and the interaction of the whole model with a Hybrid III model in a sled environment, for a total of nine different set-ups. In order to better characterize the axial behavior of the lower leg, experiments conducted on cadaveric tibia and foot were reanalyzed and experimental corridors were proposed. Future work will include additional validation of the model using global data, joint kinematics data, and deformation data at the local level.

Development of a computer model to predict aortic rupture due to impact loading

Aortic injuries during blunt thoracic impacts can lead to life threatening hemorrhagic shock and potential exsanguination. Experimental approaches designed to study the mechanism of aortic rupture such as the testing of cadavers is not only expensive and time consuming, but has also been relatively unsuccessful. The objective of this study was to develop a computer model and to use it to predict modes of loading that are most likely to produce aortic ruptures. Previously, a 3D finite element model of the human thorax was developed and validated against data obtained from lateral pendulum tests. The model included a detailed description of the heart, lungs, rib cage, sternum, spine, diaphragm, major blood vessels and intercostal muscles. However, the aorta was modeled as a hollow tube using shell elements with no fluid within, and its material properties were assumed to be linear and isotropic. In this study fluid elements representing blood have been incorporated into the model in order to simulate pressure changes inside the aorta due to impact. The current model was globally validated against experimental data published in the literature for both frontal and lateral pendulum impact tests. Simulations of the validated model for thoracic impacts from a number of directions indicate that the ligamentum arteriosum, subclavian artery, parietal pleura and pressure changes within the aorta are factors that could influence aortic rupture. The model suggests that a right-sided impact to the chest is potentially more hazardous with respect to aortic rupture than any other impact direction simulated in this study. The aortic isthmus was the most likely site of aortic rupture regardless of impact direction. The reader is cautioned that this model could only be validated on a global scale. Validation of the kinematics and dynamics of the aorta at the local level could not be done due to a lack of experimental data. It is hoped that this model will be used to design experiments that can reproduce field relevant aortic ruptures in the laboratory. Only after such experiments have been run, can local validation be examined and the model judged to be acceptable or unacceptable.

Stimulation of fracture healing in a canine ulna full-defect model by low-intensity pulsed ultrasound

Because no report has been issued on the healing effects of low-intensity pulsed ultrasound on moderate to large fracture gaps, we performed an experimental study using a canine ulna full-defect model. Ten mongrel male dogs were divided into two groups: a small defect group and large defect group. The defects were made on the middle one third of both ulnae and one side only was randomly selected for ultrasound sonication, at 1 MHz, 200 microsecond bursting sine wave in 50 mW/cm2 spacial average and temporal average. Sonication was started on the day after surgery and applied for 15 minutes once a day for six days a week. In the small defect group, the means of the radiologic scores, as described by Lane and Sandhu, were 0.6, 4.4, and 8.4 in the control side and 1.8, 6.0, and 10.4 in the treatment side one, three, and five months after the operation, respectively (p=0.0372). In the large defect model, the corresponding means were 2.2, 3.4, and 6.0 in the control side and 3.3, 5.4, and 9.2 in the treatment side (p= 0.009). Low-intensity pulsed ultrasound enhanced new bone formation in small and large full-defects and decreased the incidence of nonunion in the large defect model.

Suppression of IL-8 gene expression by radicicol is mediated through the inhibition of ERK1/2 and p38 signaling and negative regulation of NF-kappaB and AP-1

We show that radicicol, an anti-fungal agent, inhibits interleukin-8 (IL-8) production by the human monocyte line THP-1 in response to phorbol-12-myristate-13-acetate/lipopolysaccharide (PMA/LPS). IL-8 is a potent chemokine and needs for an optimal immune response--such as inflammation by activation of neutrophils. The decrease in PMA/LPS-induced IL-8 mRNA expression was demonstrated by quantitative reverse transcription-polymerase chain reaction (RT-PCR). Since the promoter in IL-8 gene contains binding motifs for NF-KB, AP-1. and NF-IL6, which appear to be important in IL-8 induction, the effects of radicicol on the activation of these transcription factors were examined. Treatment of radicicol to THP-1 cells produced a strong inhibition of NF-KB and AP-1, while NF-IL6 was not significantly affected by radicicol. Western blot analysis showed that radicicol inhibited the phosphorylation and phosphotransferase activities of extracellular signal-regulated kinases 1 and 2 (ERK1/2) and p38. PD98059 and SB203580, known as a specific inhibitor of MEKI and p38 kinase, respectively, inhibited IL-8 gene expression showing that both of the kinase pathways are involved in IL-8 regulation in human monocytes. Collectively, this series of experiments indicates that radicicol inhibits IL-8 gene expression by blocking ERK1/2 and p38 signaling.

Selective posterior rhizotomy in children with cerebral palsy: a 10-year experience

We reviewed our 10-year experience of selective posterior rhizotomy (SPR), with an emphasis on surgical outcome concentrated on improvements in functional ability and adverse effects. We had performed SPR in 208 patients between 1990 and 1999. All patients showed an overall improvement (over 95%) in spasticity, passive range of motion, and gait pattern. Preoperative ambulatory functional level and age were very important predictive factors for further improvements in postoperative functional ability. Compared with the younger children, the older ones lacked a full range of motion preoperatively, and they continued to lack a full range of motion postoperatively, despite the decrease in tone achieved by SPR. Most postoperative complications such as hypotonia, urinary retention, spinal deformities, and sensory changes were temporary and not functionally important. We conclude that SPR is an effective method of alleviating spasticity and provides lasting functional benefits at acceptable complication levels in spastic children with cerebral palsy.

A study on the eruption timing of primary teeth in Korean children

The objectives of this study were to clarify the eruption time and sequence of primary teeth in Korean children. A random sample of 1070 children from ages of four to thirty-six months was examined: 567 were males and 503 were females. The median values to measure the eruption time of the primary teeth were used. The results show that the primary teeth of boys erupt earlier than those of girls. As to the eruption sequence of primary teeth, the mandibular central incisor and second molar erupted earlier than their maxillary counterparts. For the lateral incisor, the canine and the first molar, the maxillary teeth erupted before the mandibular ones.

Prenatal development of the human mandible

In an effort to better understand the interrelationship of the growth and development pattern of the mandible and condyle, a sequential growth pattern of human mandibles in 38 embryos and 111 fetuses were examined by serial histological sections and soft X-ray views. The basic growth pattern of the mandibular body and condyle appeared in week 7 of fertilization. Histologically, the embryonal mandible originated from primary intramembranous ossification in the fibrous mesenchymal tissue around the Meckel cartilage. From this initial ossification, the ramifying trabecular bones developed forward, backward and upward, to form the symphysis, mandibular body, and coronoid process, respectively. We named this initial ossification site of embryonal mandible as the mandibular primary growth center (MdPGC). During week 8 of fertilization, the trabecular bone of the mandibular body grew rapidly to form muscular attachments to the masseter, temporalis, and pterygoid muscles. The mandible was then rapidly separated from the Meckel cartilage and formed a condyle blastema at the posterior end of linear mandibular trabeculae. The condyle blastema, attached to the upper part of pterygoid muscle, grew backward and upward and concurrent endochondral ossification resulted in the formation of the condyle. From week 14 of fertilization, the growth of conical structure of condyle became apparent on histological and radiological examinations. The mandibular body showed a conspicuous radiating trabecular growth pattern centered at the MdPGC, located around the apical area of deciduous first molar. The condyle growth showed characteristic conical structure and abundant hematopoietic tissue in the marrow. The growth of the proximal end of condyle was also approximated to the MdPGC on radiograms. Taken together, we hypothesized that the MdPGC has an important morphogenetic affect for the development of the human mandible, providing a growth center for the trabecular bone of mandibular body and also indicating the initial growth of endochondral ossification of the condyle.

Load sharing within a human lumbar vertebral body using the finite element method

STUDY DESIGN

A finite element parametric study was performed to investigate the structural roles of the vertebral cortical shell and the trabecular centrum.

OBJECTIVES

To address the debated issue of the relative load-carrying role of the vertebral cortical shell.

SUMMARY OF BACKGROUND DATA

Several experimental and computational studies have been aimed at quantifying the load-carrying roles of the human vertebral cortical shell and trabecular centrum. These studies, however, have supported no consensus.

METHODS

A finite element model of three lumbar vertebral bodies was developed to predict the fraction of the total compressive load acting on the lumbar vertebral body, under two different loading conditions, that was supported by the cortical shell. Parametric variations in vertebral material and geometric properties were examined to determine how this fraction was influenced by such changes.

RESULTS

The fraction of the compressive load supported by the cortical shell was found to be strongly dependent on the distance from the endplate, increasing from about 34% at either endplate to approximately 63% at the midtransverse plane. This fraction was independent of the loading characteristics, proportional to the properties of the cortex, and inversely proportional to the modulus of the centrum. Additionally, the cortical shell force fraction was affected significantly by changes in the overall vertebral geometry.

CONCLUSIONS

Our findings indicate that the structural dominance of the cortical shell and centrum alternate depending on the location within the vertebral body. However, as age-related bone loss progresses, the load-carrying role of the cortical shell could increase significantly.

Intraarticular entrapment of the obturator nerve in acetabular fracture

SUMMARY

The authors report a case of acetabular fracture of both columns that was associated with a rare nerve injury, entrapment of the obturator nerve in the hip joint.

Microcystin-induced down-regulation of lymphocyte functions through reduced IL-2 mRNA stability

Here we report that lymphocyte functions were down-regulated by cyanobacterial hepatotoxin microcystin. Treatment of three microcystin (MC) isotypes, MC-LR, MC-YR and nodularin, on B6C3F1 mouse splenocytes produced dose-dependent inhibition of in vitro polyclonal antibody response and lymphoproliferation to LPS. ConA-induced lymphoproliferative response was decreased by MC-YR and nodularin, but no significant effect was observed in the MC-LR treatment. Intraperitoneal administration of nodularin into B6C3F1 mice decreased humoral immune responses to sheep red blood cell (sRBC), and the inhibitory effect became severe when hepatic uptake of nodularin was blocked by rifampicin. Each MC 1 microM suppressed phorbol 12-myristate 13-acetate (PMA) plus ionomycin-induced IL-2 mRNA expression in splenocytes and thymocytes, but not in EL-4 mouse thymoma cells. To further characterize the mechanism for the reduced IL-2 mRNA level, IL-2 mRNA stability was measured using RT-PCR. Deprivation of PMA/ionomycin stimuli from activated splenocytes and blockade of new transcription resulted in destabilization of IL-2 mRNA, which was accelerated by MC treatment. These results demonstrated that MC down-regulated lymphocyte functions and the immunosuppression was mediated, at least in part, through decreased IL-2 mRNA stability.

Evidence for an association between polymorphism in the serotonin-2A receptor variant (102T/C) and increment of N100 amplitude in schizophrenics treated with clozapine

Using event-related potentials (ERPs), a reduction in the auditory N100, N200 and P300 amplitude has been found in schizophrenic patients and may represent some pathophysiological deficit. Therefore, we investigated whether the genetic variant of the serotonin-2A receptor is associated with ERP change after clozapine treatment in schizophrenic patients. Ninety-nine schizophrenic patients were included in the study. The results demonstrated that patients with 102C/C genotype have higher N100 amplitude than other patients after clozapine treatment. Our findings suggested that serotonin-2A receptor polymorphism may relate to clozapine response in schizophrenic patients. An objective and reliable tool like ERPs to assess patients' treatment response may afford more consistent results in pharmacogenetic studies.

Atomic-beam alignment of inorganic materials for liquid-crystal displays

The technique used to align liquid crystals-rubbing the surface of a substrate on which a liquid crystal is subsequently deposited-has been perfected by the multibillion-dollar liquid-crystal display industry. However, it is widely recognized that a non-contact alignment technique would be highly desirable for future generations of large, high-resolution liquid-crystal displays. A number of alternative alignment techniques have been reported, but none of these have so far been implemented in large-scale manufacturing. Here, we report a non-contact alignment process, which uses low-energy ion beams impinging at a glancing angle on amorphous inorganic films, such as diamond-like carbon. Using this approach, we have produced both laptop and desktop displays in pilot-line manufacturing, and found that displays of higher quality and reliability could be made at a lower cost than the rubbing technique. The mechanism of alignment is explained by adopting a random network model of atomic arrangement in the inorganic films. Order is induced by exposure to an ion beam because unfavourably oriented rings of atoms are selectively destroyed. The planes of the remaining rings are predominantly parallel to the direction of the ion beam.

Association analysis of polymorphism in the promoter region of the alpha2a-adrenoceptor gene with schizophrenia and clozapine response

There exists considerable evidence implicating the alpha (alpha) adrenergic system in the superior therapeutic effects of clozapine for the treatment of schizophrenia, as also its associated adverse hypersalivation side effect. It would seem plausible for variants of the adrenoceptors to be associated with the clozapine response. The present study tested the hypothesis that a biallelic polymorphism in the promoter region of the alpha2a-adrenoceptor gene confers susceptibility to schizophrenia, and is associated with a clozapine-induced (favorable) therapeutic response and/or a clozapine-induced hypersalivation. Ninety-seven treatment-resistant schizophrenic patients were assessed using the Brief Psychiatric Rating Scale before and after clozapine treatment. The results of clozapine treatment demonstrated that the alpha2a-adrenoceptor gene variants did not play a major role in the susceptibility, hypersalivation adverse effect or clozapine response of patients with schizophrenia. The polymorphism of the alpha2a-adrenoceptor gene investigated is not likely to play a major role in the pathogenesis of schizophrenic disorders or clozapine response, although the hypothesis that these genes are implicated in the cognitive deficit and polydipsia associated with schizophrenic disorders may, however, still warrant further study.

Prediction of bone strength in growing animals using noninvasive bone mass measurements

This study aims to test the hypothesis that noninvasive bone mass measurements can be used to predict bone strength in a piglet model. Dual energy X-ray absorptiometry measurements of bone mineral content (BMC), bone mineral density (BMD), and bone area (BA) were obtained from four sets of bones (left and right humeri and femora) of 12 piglets (6-68 days and 2250-17660 g). Bone strength, defined by the energy to bone failure, fracture moment, and flexural rigidity, was determined from three point bending tests using an Instron material testing system. Results show that bone mass between left and right extremities was highly correlated (r = 0.96 to 0.99, P < or 0.001 all comparisons) and was similar for bone strength (r = 0.85 to 0.98, P < 0.01 all comparisons). However, based on the standard deviation of the difference between measurements from left and right extremities, the agreement sides was better for bone mass than for bone strength measurements (r = 0.68-0.99, P < = 0.05-< or = 0.001). The predictive ability of bone mass on bone strength varied (adjusted r2 = 0.41-0.97) depending on the bone tested and the measurement parameter used, although remained statistically significant in all instances (P < 0.05-< or = 0.001). We conclude that the developing organisms, noninvasive bone mass measurements are correlated with and predictive of bone strength, although bones from the same side and same anatomical site should be used for comparison purposes.

Study of anticipation in Chinese families with schizophrenia

The anticipation phenomenon is an important aspect in several genetic disorders in which the age at onset (AAO) decreases and the severity of illness increases in successive generations. This phenomenon has been reported in several schizophrenic family studies, and expanded repeat mutations are implicated. In the present study, we investigate the anticipation phenomenon in Chinese schizophrenic families. We compare the AAO between two generations of 38 unilinear schizophrenic families. Intergenerational comparisons show that the AAO was significantly earlier in the offspring generation (mean AAO, 22.2 years) than that in the parental generation (mean AAO, 31.0 years) (P < 0.001). When only including the offspring generation who married, the AAO difference between the two generations was not significant (28.4 years vs 31.0 years, P = 0.151). Our findings suggest that a selection bias in the parental group might greatly impact the study of anticipation in schizophrenia. Other unavoidable biases associated with these analyses are discussed in the text.