Low avascular necrosis rates in femoral neck fractures: efficacy of cannulated screw fixation.

PURPOSE: Cannulated screw fixation for femoral neck fractures is often limited by concerns of avascular necrosis (AVN) occurring, historically seen in 5-40% of fixed intracapsular fractures. This study aims to assess the outcomes, particularly the AVN rate, associated with current surgical techniques within our unit. METHODS: We conducted a single-center cross-sectional study, manually searching operative records between July 14, 2014, and December 1, 2018, identifying patients with intracapsular fractured neck of femur fixed with cannulated screws, with a minimum of two years follow-up. Patient records and radiographs were reviewed for clinical and radiographic diagnoses of AVN, non-union, post-operative metalwork infection, and screw penetration of the head. Additionally, fracture pattern and displacement, screw configuration, reduction techniques, and adequacy of reduction were recorded, with radiographs independently analyzed by four orthopedic surgeons. RESULTS: Fifty-six patients were included; average age of 67 years (range 30-100). Forty-two patients (75%) sustained displaced fractures and 14 patients (25%) had undisplaced fractures. Two (4%) patients developed AVN, with no cases of non-union, post-operative metalwork infection or screw penetration of the head. Eight patients (14%) sustained a high-energy injury, though none of these patients developed AVN. All fractures required closed reduction; no open reductions performed. Twenty-seven (64%) of reductions were adequate. CONCLUSION: Our observed AVN rate is notably lower than the widely reported figures, even among a significant proportion of displaced fractures that were fixed. This study underscores that with adequate fixation, cannulated screws represent an excellent option for treating intracapsular neck of femur fractures, even in cases of displaced fracture patterns with imperfect reduction.

Effects of racket moment of inertia on racket head speed, impact location and shuttlecock speed during the badminton smash.

How the racket properties impact performance of the badminton smash is relatively unknown, and further insight could help players/coaches select the most appropriate racket. Three-dimensional position data of the racket and shuttlecock were collected (500 Hz) for 20 experienced badminton players performing a series of forehand smashes with five swingweight ([Formula: see text]) perturbed rackets, ranging from 85-106 kg·cm2. [Formula: see text] was calculated using a balance board and simple pendulum method, and modal analysis was performed using laser vibrometry to capture the fundamental frequency and distal node location for each racket. As [Formula: see text] increased a reduction in racket head speed was found with on average a 0.7 m·s-1 decrease per 5 kg·cm2 increase in [Formula: see text], however this did not lead to slower shuttlecock speeds. The impact location tended to move closer to the tip as the fundamental frequency node moved closer to the tip (as [Formula: see text] increased), providing some evidence that participants may subconsciously strike the shuttlecock at the node location to provide desirable sensory feedback. The increase in racket head speed but not shuttlecock speed was likely due to the distal increase in longitudinal impact location as [Formula: see text] increased, as well as an increase in effective mass for a given impact location. Additionally, removal of the deformation component (additional racket head speed due to the racket noticeably bending and recovering) of racket head speed increased the effect size of the relationship with [Formula: see text], where rackets with greater [Formula: see text] had larger deformation velocities. The research provides further insight into the smash performance characteristics of experienced badminton players, particularly based on racket properties. Further research is required to confirm the coincidence between node location and longitudinal impact location.

Quantitative trait loci affecting peak bone mineral density in mice.

Peak bone mass is a major determinant of risk of osteoporotic fracture. Family and twin studies have found a strong genetic component to the determination of bone mineral density (BMD). However, BMD is a complex trait whose expression is confounded by environmental influences and polygenic inheritance. The number, locations, and effects of the individual genes contributing to natural variation in this trait are all unknown. Experimental animal models provide a means to circumvent complicating environmental factors, and the development of dense genetic maps based on molecular markers now provides opportunities to resolve quantitative genetic variation into individual regions of the genome influencing a given trait (quantitative trait loci, QTL). To begin to identify the heritable determinants of BMD, we have examined genetically distinct laboratory mouse strains raised under strict environmental control. Mouse whole-body bone mineral content by dual-energy X-ray absorptiometry (DXA) correlated strongly with skeletal calcium content by ashing, and peak whole-body BMD by DXA in female mice occurred at approximately 80-90 days of age. We therefore determined mean body weight and peak whole body BMD values in 12-week-old female mice from a panel of 24 recombinant inbred (RI) BXD strains, derived from a cross between C57BL/6 and DBA/2 progenitors. The distribution of body weight and BMD values among the strains clearly indicated the presence of strong genetic influences on both of these traits, with an estimated narrow sense heritability of 60% and 35%, respectively. The patterns of differences in body weight and peak whole body BMD in the BXD strains were then integrated with a large database of genetic markers previously defined in the RI BXD strains to generate chromosome map sites for QTL. After correction for redundancy among the significant correlations, QTL analysis of the BXD RI strain series provisionally identified 10 chromosomal sites linked to peak bone mass development in the female. Several of the identified sites map near genes encoding hormones, structural proteins, and cell surface receptors that are intricately involved in skeletal homeostasis. Four QTL for body weight were also identified. One of these loci was also strongly linked to inherited variation in BMD. This finding suggests that body weight and peak BMD may be influenced by linked genes or perhaps by common genes with pleiotropic effects. Our phenotyping in the RI BXD strains has allowed us to map a number of specific genetic loci strongly related to the acquisition of peak BMD. Confirmation of these findings will likely result in the understanding of which genes control skeletal health.

Genetic sensitivity to hot-plate nociception in DBA/2J and C57BL/6J inbred mouse strains: possible sex-specific mediation by delta2-opioid receptors.

The inbred mouse strains, DBA/2J (D2) and C57BL/6J (B6), display differential sensitivity to acute, thermal nociception as measured on the hot-plate (HP) assay. In an ongoing quantitative trait locus (QTL) mapping study designed to reveal genomic loci showing genetic linkage to HP sensitivity, a putative QTL on chromosome 4 (50-80 cM from the centromere) has been identified that appears to account for variability in this trait in male, but not female mice. An obvious candidate gene located in this same chromosomal region is Oprd1, which encodes the murine delta-opioid receptor. In an attempt to evaluate whether Oprd1 represents this sex-specific QTL for HP sensitivity, we tested D2 and B6 mice of both sexes for HP latencies (hindpaw-lift, -lick or -flutter) following systemic injections of saline, or the opioid receptor antagonists naloxone (NAL; 0.1 and 10 mg/kg), nor-binaltorphimine (nor-BNI; 5 mg/kg), naltrindole (NTI; 5 mg/kg), 7-benzylidenenaltrexone (BNTX; 0.7 mg/kg), or naltriben (NTB; 1 mg/kg). High-dose (10 mg/kg) NAL lowered HP latencies in D2, but not B6 mice, suggesting that the higher HP latencies exhibited by D2 mice reflect opioid mechanisms. HP latencies in both strains and both sexes were unaffected by pretreatment with low-dose (0.1 mg/kg) NAL or nor-BNI, suggesting that neither mu nor kappa receptors affect basal nociceptive sensitivity. The delta-receptor antagonist, NTI, and the delta2-specific antagonist, NTB, (but not the delta1-specific antagonist, BNTX) effectively lowered HP latencies in a strain- and sex-dependent manner: D2 male > B6 male > D2 female > B6 female. These data support the possibility that Oprd1 is a QTL mediating HP sensitivity in mice, and more generally illustrate the important roles of genetic background and gender in the perception of pain.

Angiotensinogen genotype and blood pressure response in the Dietary Approaches to Stop Hypertension (DASH) study.

OBJECTIVE: To determine the relationship between angiotensinogen (ANG) genotype and blood pressure response to the dietary patterns of the Dietary Approaches to Stop Hypertension (DASH) trial. The angiotensin converting enzyme (ACE) gene was also tested. DESIGN: The DASH trial was a randomized outpatient feeding study comparing the effects on blood pressure (BP) of three dietary patterns: a control diet, similar to typical American intake; a 'fruits and vegetables' diet (F/V) that is rich in fruits and vegetables but otherwise resembles the control diet; and the DASH diet that is reduced in fats and that emphasizes fruits, vegetables and low-fat dairy products. Participants' genotype was also determined. SETTING: Four clinical sites. PARTICIPANTS: Adults with above-optimal BP or stage 1 hypertension. INTERVENTION: Participants ate one of the three dietary patterns for 8 weeks. Sodium intake and weight were held constant. In 355 of 459 DASH participants, DNA was extracted from leukocytes and genotyped for the G-6A ANG polymorphism and the D/I ACE polymorphism, by the polymerase chain reaction. MAIN OUTCOMES: Genotype at ANG and ACE loci; BP after 8 weeks of intervention diet. RESULTS: There was no association between ACE genotype and BP response. Associations with ANG polymorphism were significant: net systolic and diastolic BP response to the DASH diet was greatest in individuals with the AA genotype (-6.93/-3.68 mmHg) and least in those with the GG genotype (-2.80/0.20 mmHg). A similar relationship existed for the F/V diet. CONCLUSIONS: ANG genotype is associated with BP response to the DASH diet. The AA genotype confers excess risk of hypertension and is associated with increased responsiveness to diet.

Increased risk of neisserial infections in systemic lupus erythematosus.

Survival in systemic lupus erythamatosus (SLE) continues to improve because of better ancillary care, earlier diagnosis, and earlier treatment. However, infection remains a leading cause of morbidity and mortality in this disease. Although corticosteroids and immunosuppresives increase the risk of opportunistic infection, the SLE patient is still most at risk from common bacterial pathogens. As the prototypic immune-complex disease, patients with active SLE have low circulating complement as well as a reticuloendothelial system (RES) saturated with immune complexes. It seems intuitive that SLE patients should be most at risk for organisms dependent for their removal on the RES or complement for opsonization or bacteriolysis. The current series presents four patients with SLE and disseminated neisseria infection and brings to 14 the number of patients in the literature with disseminated neisserial infection. They are typically young, female, with renal disease, and either congenital or acquired hypocomplementemia, and may present with all features of a lupus flare. Surprisingly, they are not all on corticosteroids or immunosuppressives and have some features that are unusual for non-SLE patients with these infections. There seems to be an over-representation of Nisseria meningitidis (despite potential reporting bias), and there ironically may be better tolerance with fewer fulminant complications in patients who have complement deficiencies. The best approach for the physician treating SLE is to immunize all SLE patients with available bacterial vaccines to N meningitidis and Streptococcus pneumonia, have a low threshold of suspicion for the diagnosis of disseminated neisserial or other encapsulated bacterial infection in the SLE patient who is sick, and to treat empirically with third generation cephalosporins after appropriate cultures.

Perceptual and cognitive factors governing performance in comparative arrival-time judgments.

Four experiments were conducted to investigate factors affecting relative arrival-time judgments in the transverse plane. Across experiments, results indicated an overreliance on relative distance information. The levels of relative velocity and distance used in the arrival-time task were proved discriminable, and performance in both relative velocity and distance judgments predicted performance in the relative arrival-time task. Despite the distance bias, an attempt to integrate relative velocity and distance information was also evidenced. The distance bias appears to have resulted from resource limitations on the concurrent processing of relative velocity and distance information, causing relative velocity information to become resource limited. The final experiment assessed the stability of performance in each of the tasks over time and provided evidence of individual differences in the ability to coordinate information from multiple sources.

Hand preference and performance on unimanual and bimanual tasks in capuchin monkeys (Cebus apella).

Patterns of manual preference and the extent to which preference provided a benefit in performance (movement time) were evaluated in 7 young adult capuchin monkeys (Cebus apella). Directions of preference were inconsistent within individual animals across home-cage activities, unimanual, and bimanual experimental tasks. Preferences were more strongly expressed in the experimental tasks than in the home cage. A left bias in the population for prehension, predicted by recent theories, was not evident in any setting. Movement time was moderately negatively correlated with degree of preference within experimental tasks. The benefit to performance conferred by lateral preference was not dependent on whether the right or left hand was preferred. Lateralization of prehension appears to be a flexible process in these monkeys, which can result in quickly realized benefits in some conditions.

Disseminated neisserial infection in pregnancy: the empress may have a change of clothing.

A case of disseminated neisserial disease during pregnancy with good perinatal outcome is presented along with two examples of disseminated N. meningitidis from endocervical site. Upon close review, it is clear that the biological similarities of both N. gonorrhoeae and N. meningitidis may outweigh their differences. The two organisms may behave in clinically indistinguishable fashion and probably justify a more cautious approach to the clinical syndromes we have considered the inviolate domain of the gonococcus. The management of disseminated neisserial disease in pregnancy should include prompt empiric parenteral therapy while aggressive diagnostic confirmation of the organism is pursued. In addition, neonatal conjunctivitis caused by a Gram-negative diplococci should be treated parenterally until clinical response and identity of the organism is confirmed.

Structure of peripheral cementum of normal equine cheek teeth.

The structure of peripheral cementum of mandibular and maxillary cheek teeth was studied by gross observation, light microscopy, and scanning and transmission electron microscopy. Teeth from four horses aged 4, 8, 17, and 30-years-old were examined. The cementum of the occlusal surface was thicker on the buccal aspect when compared with the lingual aspect of mandibular teeth. The cementum of the occlusal surface was thicker on the palatal aspect when compared with the buccal aspect of maxillary teeth. There was no peripheral cementum on the interdental aspects of either mandibular or maxillary cheek teeth. In the adult tooth, cementum covered the crown and root surfaces. The peripheral cementum of the gingival region showed a dramatic increase in thickness compared with cementum covering the alveolar portion of the embedded tooth. At a microscopic level, three layers (primary, secondary, and tertiary) were identified within cementum. The increase in cementum in the gingival region was of tertiary cementum. All three layers contained vital cementocytes. There was a well-developed vascular system within the cementum. Nerve bundles were also present. Three cementoblast profiles were identified at the junction of the cementum with the periodontal ligament. The results reported in this paper show that cementum is a dynamic vital tissue. These findings should contribute to a greater understanding of the etiology and pathogenesis of cemental caries and periodontal disease in the horse.

High-energy open tibial fractures in children: treatment with a programmable circular external fixator.

Between 2005 and 2010 ten consecutive children with high-energy open diaphyseal tibial fractures were treated by early reduction and application of a programmable circular external fixator. They were all male with a mean age of 11.5 years (5.2 to 15.4), and they were followed for a mean of 34.5 months (6 to 77). Full weight-bearing was allowed immediately post-operatively. The mean time from application to removal of the frame was 16 weeks (12 to 21). The mean deformity following removal of the frame was 0.15° (0° to 1.5°) of coronal angulation, 0.2° (0° to 2°) sagittal angulation, 1.1 mm (0 to 10) coronal translation, and 0.5 mm (0 to 2) sagittal translation. All patients achieved consolidated bony union and satisfactory wound healing. There were no cases of delayed or nonunion, compartment syndrome or neurovascular injury. Four patients had a mild superficial pin site infection; all settled with a single course of oral antibiotics. No patient had a deep infection or re-fracture following removal of the frame. The time to union was comparable with, or better than, other published methods of stabilisation for these injuries. The stable fixator configuration not only facilitates management of the accompanying soft-tissue injury but enables anatomical post-injury alignment, which is important in view of the limited remodelling potential of the tibia in children aged > ten years. Where appropriate expertise exists, we recommend this technique for the management of high-energy open tibial fractures in children.

Slipped capital femoral epiphysis.

Slipped capital femoral epiphysis is a condition likely to be encountered by all practising orthopaedic surgeons. A sound knowledge of the risk factors, presentation, investigation and management is essential to prevent the potentially significant consequences of missing the diagnosis. We present an overview of the condition, along with a review of the relevant literature to date.

Monitoring waste in an intravenous admixture program.

A method for collecting and analyzing data on i.v. admixture waste is described, and examples of the use of these data to reduce waste are presented. In 1984, a pharmacy department serving 580 hospital beds projected annual expense for waste of i.v. products to be nearly $30,000. Five major changes were implemented to reduce waste. Modification of expiration dating policies for cefoxitin and tobramycin substantially reduced waste. After an operating room pharmacy satellite was opened, decreased waste of dobutamine, dopamine, nitroglycerin, and nitroprusside was estimated to save $1000 per year. Changing times of batch processing of i.v. admixtures resulted in cost savings that were not significantly different for three-month periods before and after the change. The method of identifying small-volume injections (SVIs) to be manufactured was improved, and SVIs of expensive drugs were prepared every 12, instead of 24, hours; these changes resulted in reduction of one technician full-time equivalent but little change in the percentage or cost of SVIs wasted. Decentralized pharmacists were asked to order certain items on an as-needed basis; this did not affect costs or waste. From 1984 to 1985, total costs associated with waste decreased an estimated $11,000, or 27.5%. This department's attempt to change i.v. admixture procedures based on timely data has resulted in substantial reductions in the cost of waste.

Characterization of CYP4A induction in rat liver by inflammatory stimuli: dependence on sex, strain, and inflammation-evoked hypophagia.

Acute treatment of rats with bacterial endotoxin or particulate irritants induces the expression of CYP4A mRNAs in rat liver and kidney. To determine whether all or part of these effects could be caused by hypophagia associated with the treatments, we pair-fed saline-injected rats to rats injected with endotoxin or the particulate irritant BaSO(4). The effects of endotoxin on hepatic or renal CYP4A1, CYP4A2, or CYP4A3 expression 24 h after injection were clearly distinguishable in kinetics and magnitude from those of pair feeding, indicating that the effects of endotoxin are not caused by hypophagia. Conversely, BaSO(4) treatment caused a more profound hypophagia, and pair feeding to these animals produced effects similar to those of the irritant treatment, indicating that CYP4A induction by BaSO(4) is mainly caused by reduced food intake. To gain further insight into the mechanism of induction of CYP4A by these inflammatory agents, we studied the sex dependence of their effects in Fischer 344 and Sprague-Dawley rats. No significant strain differences were observed, but the induction of hepatic CYP4A mRNAs by endotoxin or BaSO(4) was either absent in females or significantly lower than in males. This sex specificity of induction of hepatic CYP4As has been reported previously for peroxisome proliferators, and thus our results are consistent with a role for the peroxisome proliferator-activated receptor-alpha in the induction of hepatic CYP4As by inflammatory agents.

Evaluation of potential genetic associations between ethanol tolerance and sensitization in BXD/Ty recombinant inbred mice.

Ethanol (EtOH) has both locomotor stimulant and locomotor ataxic effects. Repeated EtOH treatment can result in the development of behavioral sensitization (increased sensitivity) similar to that seen with the classical stimulant drugs amphetamine and cocaine. However, it has been suggested for EtOH that sensitization may be a by-product of the development of tolerance to the sedative/ataxic effects of EtOH. It is also possible that the converse is true: that tolerance develops as the result of sensitization development. We examined this notion by measuring EtOH sensitization and tolerance in the BXD/Ty recombinant inbred strains. Changes in locomotor activation and grid test ataxia were used as the measures of sensitization and tolerance, respectively. If a genetic relationship exists between sensitization and tolerance, then those strains most susceptible to sensitization should also develop the most robust tolerance. Genetic correlations did not support the presence of this relationship. In addition, the use of the BXD/Ty recombinant inbred strains enabled us to perform gene mapping by quantitative trait locus analysis for activity and ataxia measures. We found that 28% to 79% of the genetic variation in the various activity and ataxia responses could be explained by the identified quantitative trait loci associations. However, when associations of gene markers with behavioral phenotypes were compared, we obtained no strong evidence for common genes determining magnitude of sensitization and tolerance. Thus the results of this study do not support the hypothesis that sensitization results from development of tolerance to the sedative/ataxic effects of EtOH or, conversely, that tolerance is a by-product of sensitization.

Natural killer cells can enhance the proliferative responses of B lymphocytes.

In addition to lytic activity against malignant and virally transformed target cells, recent evidence has suggested that natural killer (NK) cells can modulate immune activities such as the suppression of B cell responses through noncytotoxic means. Using human B cells and highly purified autologous NK cells, we have demonstrated that NK cells can substantially augment the proliferative responses of B cells stimulated with the surface immunoglobulin crosslinking agents anti-IgM or Staphylococcus aureus Cowan strain I (SAC). This "enhancer" activity of NK cells was quite potent and was observed at an NK:B cell ratio as low as 0.05. Peak blastogenic responses of B cells cocultured with NK cells in the presence of B cell activators were observed at 2-3 days, similar to the responses of B cells in the absence of NK cells. Using the inhibitor of DNA synthesis mitomycin C, we determined that B cells and not NK cells were proliferating in cocultures of these lymphocytes stimulated with SAC. Activated B cells neither prevented the lysis of the isotope-labeled NK-sensitive target cell line K562 nor formed conjugates with NK cells, suggesting that cell contact was not a prerequisite for the effect. These studies have further expanded the functional repertoire of NK cells to include enhancer as well as suppressor and lytic activities.