Abstract 1374: The novel PARP1-selective inhibitor AZD5305 has reduced hematological toxicity when compared to PARP1/2 inhibitors in pre-clinical models

Current clinical poly (ADP-ribose) polymerase (PARP) inhibitors target both PARP1 and PARP2 and they all cause clinical cytopenias with varying severity. Understanding the mechanism underlying the hematological toxicity of these agents is key for the rational design of a best-in-class molecule with greater therapeutic potential, both as monotherapy and in combination with chemotherapy.

We validated the rat as a physiologically competent translational model to investigate PARP inhibitor-driven hematological toxicity. Here we demonstrate that in comparison with a representative PARP1/2 inhibitor, olaparib, the novel highly potent PARP1-selective inhibitor and trapper, AZD5305, does not cause hematological toxicity as a monotherapy in pre-clinical rat models at predicted clinically efficacious exposures. Thus, monotherapy toxicity of PARP1/2 inhibitors likely depends on PARP2 inhibition.

Next, we proceeded to investigate whether PARP1-selective inhibition would be better tolerated in chemotherapy combinations than PARP1/2 inhibition. We performed a rat in vivo study comparing daily olaparib or daily AZD5305 at matched exposures in combination with one cycle of intravenous carboplatin for 14 days. We show that olaparib and PARP1-selective AZD5305 cause comparable exacerbation of carboplatin-induced peripheral blood effects implicating PARP1 inhibition in combination-driven hematological toxicity. Importantly however, AZD5305+carboplatin showed improved hematological tolerability over olaparib+carboplatin because peripheral reticulocytes and bone marrow erythroid precursor cells recover in the presence of continuous AZD5305 but not in the presence of continuous olaparib. Importantly, this differentiation was maintained in a subsequent rat in vivo study, where daily olaparib or daily AZD5305 were combined with two three-weekly cycles of a higher dose of carboplatin to more closely mimic clinical protocol. AZD5305+carboplatin was associated with a more rapid recovery of reticulocytes, red blood cells and hemoglobin following both cycles of carboplatin. In contrast, olaparib+carboplatin was associated with a slower recovery resulting in a more sustained reduction in red cells and hemoglobin during both the first and second cycle of carboplatin.

Thus, in rodents the novel potent PARP1-selective inhibitor AZD5305 has improved hematological tolerability over dual PARP1/2 inhibitors, both as a monotherapy and in carboplatin combinations.

Citation Format: Sonja J. Gill, Ruth Macdonald, Carmen Pin, Rob Collins, Emilyanne Leonard, Gareth Maglennon, Andy Pike, Peter Cotton, Glen Hawthorne, Jordan Pugh, Rebecca Sargeant, Daniel Sutton, James Atkinson, Stewart Jones, Sarah Chinery, Mark Anderton. The novel PARP1-selective inhibitor AZD5305 has reduced hematological toxicity when compared to PARP1/2 inhibitors in pre-clinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1374.

Common mental disorders among Irish jockeys: prevalence and risk factors

OBJECTIVE

Jockeys compete in a sport, horseracing, renowned for its physical and psychological demands. Previous research has identified that common mental disorders (CMDs) may be prevalent among this unique population of athletes. The aim of the present study was to further explore the prevalence of CMDs among jockeys and to test for associations with potential risk factors.

METHODS

An anonymous survey was distributed to professional jockey online. Self-report screening tools for four CMDs (psychological distress, depression, generalized anxiety, and adverse alcohol use) were included alongside predictor variables from questionnaires assessing for burnout, career satisfaction, social support, and the contemplation of retirement. Binary logistic regression was used to explore associations between CMDs (present versus not present) and risk factors. Eighty-four professional jockeys completed the questionnaire (response rate = 52%).

RESULTS

In total, 79% of jockeys met the threshold for at least one CMD. Prevalence (%) of CMD varied as follows: adverse alcohol (61%), depression (35%), generalized anxiety (27%), and psychological distress (19%). Burnout, career (dis)satisfaction, lower levels of social support, and the contemplation of retirement increased the odds of meeting the criteria for CMDs.

CONCLUSION

The findings indicate that jockeys report CMD symptoms at comparable rates to athletes in other sports. The study was the first to highlight potential risk factors as predictors of CMDs among jockeys, including burnout, career satisfaction, and the current contemplation of retirement. Screening tools for the risk factors demonstrated may, therefore, provide useful in the early identification of CMDs among jockeys. The development of jockey-specific assessment tools, education programmes, and interventions may help better understand and support the mental health of jockeys.

A Stuck Hemodialysis Central venous Catheter

Background

A growing number of hemodialysis patients are dependent upon central venous catheters (CVCs) for long-term vascular access. Although many complications of CVCs have been documented, the phenomenon of the stuck catheter is described relatively infrequently.

Case report

We describe a case where attempts to remove the line by exploration of the jugular insertion site in theater were unsuccessful and the line was internalized.

Discussion

The case is then discussed with all available cases in the literature to suggest principles of managing and preventing the stuck catheter phenomenon.

Monolithically multi-color lasing from an InGaN microdisk on a Si substrate

An optically pumped multi-color laser has been achieved using an InGaN/GaN based micro-disk with an undercut structure on a silicon substrate. The micro-disk laser has been fabricated by means of a combination of a cost-effective microsphere lithography technique and subsequent dry/wet etching processes. The microdisk laser is approximately 1 μm in diameter. The structure was designed in such a way that the vertical components of the whispering gallery (WG) modes formed can be effectively suppressed. Consequently, three clean lasing peaks at 442 nm, 493 nm and 522 nm have been achieved at room temperature by simply using a continuous-wave diode laser as an optical pumping source. Time-resolved micro photoluminescence (PL) measurements have been performed in order to further confirm the lasing by investigating the excitonic recombination dynamics of these lasing peaks. A three dimensional finite-difference-time-domain (FDTD) simulation has been used for the structure design.

Risk assessment tools in criminal justice and forensic psychiatry: The need for better data

Violence risk assessment tools are increasingly used within criminal justice and forensic psychiatry, however there is little relevant, reliable and unbiased data regarding their predictive accuracy. We argue that such data are needed to (i) prevent excessive reliance on risk assessment scores, (ii) allow matching of different risk assessment tools to different contexts of application, (iii) protect against problematic forms of discrimination and stigmatisation, and (iv) ensure that contentious demographic variables are not prematurely removed from risk assessment tools.

A stuck hemodialysis central venous catheter

BACKGROUND

A growing number of hemodialysis patients are dependent upon central venous catheters (CVCs) for long-term vascular access. Although many complications of CVCs have been documented, the phenomenon of the stuck catheter is described relatively infrequently.

CASE REPORT

We describe a case where attempts to remove the line by exploration of the jugular insertion site in theater were unsuccessful and the line was internalized.

DISCUSSION

The case is then discussed with all available cases in the literature to suggest principles of managing and preventing the stuck catheter phenomenon.

A comparison of diabetic foot ulcer patients managed in VHA and non-VHA settings

OBJECTIVE

To compare patients with diabetes and new onset foot ulcers treated in Veterans Health Administration (VHA) and non-VHA settings.

METHODS

The treatment of patients with new onset diabetic foot ulcers was prospectively monitored in three VHA and three non-VHA hospitals and outpatient settings until ulcer healing, amputation, or death.

RESULTS

Of the 302 individuals enrolled in this study, 47% were veterans receiving VHA care. There were no significant differences between veterans and nonveterans in baseline wound classification, diabetes severity, or comorbid conditions. Veterans received significantly fewer sharp debridements, total contact casts, and custom inserts than their nonveteran counterparts, and they had significantly more x-rays, local saline irrigations, IV antibiotics, and prescriptions for bed rest. The percentage of amputations was higher in veterans but did not achieve statistical significance.

CONCLUSIONS

Many commonly held stereotypes of veteran men were not found. Veterans and nonveterans with foot ulcers were similar in terms of health and foot history, diabetes severity, and comorbid conditions. There was considerable variation in treatment of diabetic foot ulcers between VHA and non-VHA care. Yet this variation did not result in statistically significant differences in ulcer outcomes.

Intermediate outcomes by race and ethnicity in peritoneal dialysis patients: results from the 1997 ESRD Core Indicators Project. National ESRD Core Indicators Workgroup

BACKGROUND

Hispanics are the fastest growing minority group in the United States, and approximately 10% of all end-stage renal disease (ESRD) patients are Hispanic. Few data are available, however, regarding dialysis adequacy and anemia management in Hispanic patients receiving peritoneal dialysis in the U.S.

METHODS

Data from the Health Care Financing Administration (HCFA) ESRD Core Indicators Project were used to assess racial and ethnic differences in selected intermediate outcomes for peritoneal dialysis patients.

RESULTS

Of the 1219 patients for whom data were available from the 1997 sample, 9% were Hispanic, 24% were non-Hispanic blacks, and 59% were non-Hispanic whites. Hispanics were more likely to have diabetes mellitus as a cause of ESRD compared to blacks or whites, and both Hispanics and blacks were younger than white patients (both p < 0.001). Although whites had higher weekly Kt/V and creatinine clearance values compared to blacks or Hispanics (p < 0.05), blacks had been dialyzing longer (p < 0.01) and were more likely to be anuric compared to the other two groups (p < 0.001). Blacks had significantly lower mean hematocrit values (p < 0.001) and a greater proportion of patients who had a hematocrit level less than 28% (p < 0.05) compared to Hispanics or whites, despite receiving significantly larger weekly mean epoetin alfa doses (p < 0.05) and having significantly higher mean serum ferritin concentrations (p < 0.01). Multivariate logistic regression analysis revealed significant differences by race/ethnicity for experiencing a weekly Kt/V urea < 2.0 and hypertension, but not for other intermediate outcomes examined (weekly creatinine clearance < 60 L/week/1.73 m2, Hct < 30%, and serum albumin < 3.5/3.2 g/dL).

CONCLUSION

Hispanics had adequacy values similar to blacks and anemia parameters similar to whites. Additional studies are needed to determine the etiologies of the differences in intermediate outcomes by racial and ethnic groupings in peritoneal dialysis patients.

Insider/outsider partnerships in an ethnographic study of shared governance

The benefits of research being undertaken by more than one researcher cannot be underestimated. Having one researcher with intimate knowledge of the organisation and another who could provide a dispassionate view, paid dividends in this study into shared governance from an ethnographic perspective.

Nontraumatic lower extremity amputations in the Medicare end-stage renal disease population

BACKGROUND

Nontraumatic lower limb amputation is a serious complication of both diabetic neuropathy and peripheral vascular disease. Many people with end-stage renal disease (ESRD) suffer from advanced progression of these diseases. This study presents descriptive information on the rate of lower limb amputation among people with ESRD who are covered by the Medicare program.

METHODS

Using hospital bill data for the years 1991 through 1994 from the Health Care Financing Administration's ESRD program management and medical information system (PMMIS), amputations were based on ICD9 coding. These hospitalizations were then linked back to the PMMIS enrollment database for calculation of rates.

RESULTS

The rate of lower limb amputation increased during the four-year period from 4.8 per 100 person years in 1991 to 6.2 in 1994. Among persons whose renal failure was attributed to diabetic nephropathy, the rates in 1991 and 1994 were 11.8 and 13.8, respectively. The rate among diabetic persons with ESRD was 10 times as great as among the diabetic population at large. Two thirds died within two years following the first amputation.

CONCLUSIONS

The ESRD population is at an extremely high risk of lower limb amputation. Coordinated programs to screen for high-risk feet and to provide regular foot care for those at high risk combined with guidelines for treatment and referral of ulceration are needed.

Racial/ethnic analysis of selected intermediate outcomes for hemodialysis patients: results from the 1997 ESRD Core Indicators Project

Principal goals of the End-Stage Renal Disease (ESRD) Core Indicators Project are to improve the care provided to ESRD patients and to identify categorical variability in intermediate outcomes of dialysis care. The purpose of the current analysis is to extend our observations about the variability of intermediate outcomes of ESRD care among different racial and gender groups to a previously unreported group, Hispanic Americans. This group is a significant and growing minority segment of the ESRD population. A random sample of Medicare-eligible adult, in-center, hemodialysis patients was selected and stratified from an end-of-year ESRD patient census for 1996. Of the 6,858 patients in the final sample, 45% were non-Hispanic whites, 36% were non-Hispanic blacks, and 11% were Hispanic. Whites were older than blacks or Hispanics (P < 0.001). Hispanics were more likely to have diabetes mellitus as a primary diagnosis than either blacks or whites (P < 0.001). Even though they received longer hemodialysis times and were treated with high-flux hemodialyzers, blacks had significantly lower hemodialysis doses than white or Hispanic patients (P < 0.001). The intradialytic weight losses were greater for blacks (P < 0.05). The delivered hemodialysis dose was lower for blacks than for whites or Hispanics whether measured as a urea reduction ratio (URR) or as the Kt/V calculated by the second generation formula of Daugirdas (median 1. 32, 1.36, and 1.37, respectively, P < 0.001). Hispanics and whites had modestly higher hematocrits than blacks (33.2, 33.2, and 33.0%, respectively, P < 0.01). There was no significant difference among groups in the weekly prescribed epoetin alfa dose ( approximately 172 units/kg/week). A significantly greater proportion of Hispanic patients had transferrin saturations >/=20% compared with the other two groups (P < 0.001). Logistic regression modeling revealed that whites were significantly more likely to have serum albumin <3. 5(BCG)/3.2(BCP) gm/dL (OR 1.4, p < 0.01); blacks were significantly more likely to have a delivered Kt/V < 1.2 (OR 1.4, P < 0.001) and hematocrit <30%, (OR 1.2; P < 0.05) and both blacks and Hispanics were significantly more likely to have a delivered URR < 65% (OR 1.5, P < 0.001 and 1.2, P < 0.05, respectively).

Instability of the CAG repeat in immortalized fibroblast cell cultures from Huntington's disease transgenic mice

Huntington's Disease transgenic mice were used for an exploration into the stability of a trinucleotide repeat. The brain shows heterogeneous somatic instability that increases quantitatively with age. To test somatic CAG-repeat alterations during long-term culture, DNA was extracted from transgenic tissue, primary fibroblasts, and SV40-immortalized fibroblasts at intervals of approximately 100 cell doublings. In fibroblasts derived from an adult mouse, there was an initial short truncation of the repeat, followed by an emerging population of cells showing continuous slow expansion. After 15 months in continuous culture (approximately 600 cell doublings following transformation) the major CAG peak has increased from 155 to approximately 170 triplets. This in vitro system can now be used to assay factors that affect instability.

Pioneering the 12-hour shift in Australia--implementation and limitations

Twelve-hour shift rostering offers an alternative to the traditional 8- and 10-hour shifts usually worked in Australian nursing practice. This paper outlines the implementation process involved in introducing 12-hour shifts in a Melbourne hospital intensive care unit. The process was instigated by the nursing staff. After extensive consultation with the union and hospital management, a roster pattern of two 12-hour days, followed by 12-hour night shifts then days off, was introduced. Independent researchers were engaged to evaluate the impact of the 12-hour shifts on staff well-being and work performance. Effects on staff retention, sick leave and inservice education were examined. The researchers found that well-being and work performance were minimally affected by the 12-hour shift roster, while staff retention and sick leave were unaffected. Further, the pattern of 12-hour shifts, which was democratically implemented, was preferred by the nursing staff and did not diminish their well-being and work performance.

Shared governance as a way to involve staff in decision-making

Increasing the involvement of clinicians in decision-making is a key part of recent NHS policy. One model designed to increase involvement is shared governance. This article describes the approach to shared governance developed at Kettering General Hospital. Ongoing evaluation of the scheme suggests benefits in terms of personal and professional development for those involved.

How patients adapt diabetes self-care recommendations in everyday life

BACKGROUND

Our study explored behavioral factors affecting what patients with type 2 diabetes do for self-care and why they do it. The findings were used to develop clinical recommendations to improve intervention strategies.

METHODS

Interviewers, using open-ended questions, explored patients' own perceptions and assessments of self-care behaviors. The fifty-one subjects were self-identified Mexican Americans who had type 2 diabetes for at least 6 months, and had no major impairment as a result of this diabetes. Texts of patient interviews were analyzed by building and refining matrixes to display and compare central themes regarding treatment strategies and their contexts.

RESULTS

All patients were trying to control their diabetes, but none of them followed recommendations completely. Instead, they adapted self-care behaviors to the exigencies of everyday life. Key factors influencing patients' treatment choices were: (1) the belief in the power of modern medicine; (2) the desire to act and feel "normal"; (3) the desire to avoid physical symptoms; and (4) limited economic resources.

CONCLUSIONS

As patients apply treatment recommendations in the context of their everyday lives, they continually must make many small decisions affecting self-care behavior. The specific contexts of patients' lives, including their economic, educational, and cultural circumstances, determine how the generalized principles of type 2 diabetes management are implemented. Clinical strategies must be responsive to these circumstances in order to enable patients to make appropriate decisions when adapting their self-care behaviors to their own situations.

Evidence that hepatocyte turnover is required for rapid clearance of duck hepatitis B virus during antiviral therapy of chronically infected ducks

Duck hepatitis B virus (DHBV) DNA synthesis in congenitally infected ducks is inhibited by 2'-deoxycarbocyclic guanosine (2'-CDG). Three months of therapy reduces the number of infected hepatocytes at least 10-fold (W.S. Mason, J. Cullen, J. Saputelli, T.-T. Wu, C. Liu, W.T. London, E. Lustbader, P. Schaffer, A.P. O'Connell, I. Fourel, C.E. Aldrich, and A.R. Jilbert, Hepatology 19:393-411, 1994). The present study was performed to determine the kinetics of disappearance of infected hepatocytes and to evaluate the role of hepatocyte turnover in this process. Essentially all hepatocytes were infected before drug therapy. Oral treatment with 2'-CDG resulted in a prompt reduction in the number of infected hepatocytes. After 2 weeks, only 30 to 50% appeared to still be infected, and less than 10% were detectably infected after 5 weeks of therapy. To assess the possible role of hepatocyte turnover in these changes, 5-bromo-2'-deoxyuridine (BUdR) was administered 8 h before liver biopsy to label host DNA in hepatocytes passing through S phase, and stained nuclei were detected in tissue sections by using an antibody reactive to BUdR. The extent of nuclear labeling after 5 weeks was the same as that before therapy (ca. 1%). However, biopsies taken after 2 weeks of therapy showed a ca. 10-fold elevation in the number of nuclei labeled with BUdR. This result suggested that a rapid clearance of infected hepatocytes by 2'-CDG was caused not just by the inhibition of viral replication but also by an acceleration of the rate of hepatocyte turnover. To test this possibility further, antiviral therapy was carried out with another strong inhibitor of DHBV DNA synthesis, 5-fluoro-2',3'-dideoxy-3'-thiacytidine (524W), which did not accelerate hepatocyte turnover in ducks. 524W administration led to a strong inhibition of virus production but to a slower rate of decline in the number of infected hepatocytes, so that ca. 50% (and perhaps more) were still infected after 3 months of therapy. In addition, histopathologic evaluation of 2'-CDG-treated ducks revealed liver injury, especially at the start of therapy. No liver damage was observed during 524W therapy. These results imply that clearance of infected hepatocytes from the liver is correlated with hepatocyte turnover. Thus, in the absence of immune clearance or other sources for the accelerated elimination of infected hepatocytes, inhibitors of virus replication would have to be administered for a long period to substantially reduce the burden of infected hepatocytes in the liver.

Methodological approaches to disinfection of human hepatitis B virus

Three commercial disinfectants (two quaternary formulations and one phenolic) were tested against human hepatitis B virus (HHBV). The treated virus was assayed for infectivity by the chimpanzee assay and for morphological alteration by the Morphological Alteration and Disintegration Test. The same agents were tested against duck hepatitis B virus in a duck hepatocyte infectivity assay. It is apparent that human and duck hepatitis viruses were relatively susceptible to disinfection, becoming noninfectious after < or = 10 min of contact with the disinfectant. The Morphological Alteration and Disintegration Test accurately predicted activity in the two infectivity tests. The anti-human hepatitis B virus effect of the low-level quaternary ammonium germicides is a novel finding and suggest that members of the family Hepadnaviridae are relatively susceptible to chemical agents.

Total serum cholesterol levels in Asians living in New York City: results of a self-referred cholesterol screening

Asians historically have low total cholesterol levels and low incidence of coronary heart disease. In performing a coronary heart disease and total cholesterol screening in New York City's Chinatown, we obtained data supportive of previous studies, which focused on Japanese populations and described the influence of environment on total cholesterol. In the present study, Chinese living in Chinatown have higher levels of total cholesterol than would be expected from studies of Chinese living in Shanghai. For every age group examined, Asian-born Chinese living in Chinatown had higher total cholesterol levels than both urban and rural Chinese in Shanghai. In subjects less than or equal to 30 years of age, urban males in Shanghai had cholesterol levels of 160 +/- 34 mg/dL, compared with 206 +/- 38 mg/dL for Asian-born males in Chinatown. For females in the same age category, cholesterol levels were 162 +/- 35 mg/dL vs 224 +/- 45 mg/dL, respectively. Applying National Cholesterol Education Panel (NCEP) guidelines, the distribution of desirable, borderline-high, and high blood cholesterol levels for the Chinese in Chinatown (41%, 35%, and 23%, respectively) were similar to a group of Caucasians screened (42%, 32%, and 26%) and the group recently used to determine the prevalence of high blood cholesterol in American adults (43%, 30%, and 27%). Studies are needed to stratify the risk of coronary heart disease in other groups that traditionally have a low incidence of coronary heart disease, but which now have adopted Western lifestyles.

Synthesis of hepadnavirus particles that contain replication-defective duck hepatitis B virus genomes in cultured HuH7 cells

To evaluate the possibility of producing transducible replication-defective hepadnaviruses, cloned mutant duck hepatitis B virus genomes were tested both for virus antigen production and viral DNA synthesis following transfection into the human hepatoma cell line HuH7. Deletion of a cis-acting 12-nucleotide sequence implicated in viral DNA synthesis, direct repeat 1 (DR1), resulted in the loss of ability to synthesize both mature viral DNA and infectious virus. The delta DR1 mutant, however, produced envelope and core antigens and was shown to provide trans-acting functions required for the assembly of infection-competent particles. Thus, mutants with mutations in viral genes could be rescued as DNA-containing viral particles after cotransfection with delta DR1. The efficiency of rescue was influenced by the site of mutation. A mutant DNA encoding truncated core and envelope proteins not only was poorly rescued but also was able to suppress the production from a wild-type DNA of infectious virus.

Deterioration of trapeziometacarpal arthritis due to trigger thumb: a biomechanical evaluation

Patients with trigger thumb and trapeziometacarpal joint arthritis accompanied by swan-neck deformity of their first rays find that their arthritic pain becomes worse whenever their thumbs "catch." Six hands with adduction contracture and arthritis of the trapeziometacarpal joint are studied biomechanically and demonstrate significantly excessive shear forces (p less than 0.01) around their trapeziometacarpal joint relative to six normal hands. Increased pain with deformity suggests aggressive treatment of trigger thumb in cases such as these.

Normal pelvic strain pattern in vitro

Four cadaver pelves were dissected of soft tissue and each of the eight hemipelves instrumented with ten rosette strain gauges. Static loading was conducted to simulate single leg stance, and applied through the intact hip joint. The medial portion of the pelvis was under tension directed vertically and the lateral ilium was in compression. This strain pattern is consistent with bending applied to the ilium from the action of the abductor and joint reaction forces.

Characterization of the major duck hepatitis B virus core particle protein

The amino acid composition of the major duck hepatitis B virus (DHBV) core particle proteins was determined. The results of this analysis indicated that cores are composed of a single major protein that initiates translation from the second available AUG in the DHBV core gene. Proteins isolated from core particles purified from the cytoplasm of DHBV-infected duck hepatocytes exhibited heterogeneity in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, independent of the stage of viral DNA maturation. Incubation of native cores with alkaline phosphatase removed this heterogeneity, indicating that phosphorylation of external amino acids was responsible. Core protein isolated from mature DHBV purified from serum of infected animals did not display heterogeneity, suggesting a possible role for dephosphorylation in virus maturation.

Cortical pelvic strains with varying size hemiarthroplasty in vitro

Four human pelves were dissected of soft tissues and instrumented with rosette strain gages. The pelves were left intact (not separated at the pubic symphysis or sacroiliac joints) although each of the eight hemipelves was tested separately. The pelves were loaded to simulate single leg stance with use of a wire mesh cemented to the wing of the ilium, representing the abductor muscles. Loading was carried out with the intact hip joint and 1 mm undersized, correct sized, and 1 mm oversized hemiarthroplasty. The correct sized component produced a strain pattern closet to normal. The oversized component was associated with an increase in strain at the medial acetabular dome.

Nebuhaler or nebulizer for high dose bronchodilator therapy in chronic bronchitis: a comparison

We have compared the clinical efficacy of high dose terbutaline sulphate (10 mg four times daily) delivered by either a Nebuhaler or jet nebulizer in 13 patients with chronic bronchitis in a 2-week, open, crossover study. Both treatment regimens improved run-in symptom scores but no significant changes were recorded in peak flow and spirometry. Side-effects were more common with the Nebuhaler and more patients preferred the nebulizer. However, the Nebuhaler is an alternative therapeutic option for delivery of high doses of bronchodilators in patients with chronic bronchitis.

Alterations in primary and coupled neck motions after facetectomy

Normal neck motion is a complicated phenomenon. A primary motion results from an applied force or torque. Secondary coupled motions also result as a consequence of the primary motion. These resulting coupled motions were measured in isolated cervical motion segments using three-dimensional videophotogrammetry with a coordinate system fixed in space. A cross coupling algorithm provided error correction and conversion from local to true cartesian coordinates. The data were analyzed by computer, and the true coupled motions resulting from any applied force were obtained. A second group of specimens was facetectomized, and the experiments were repeated. After facetectomy, a moment about the anteroposterior axis resulted in marked reduction in lateral displacement, decrease in vertical displacement, and decrease in rotation about the vertical axis. Results were significant at P less than 0.01 and represent a significant decrease in coupled motions resulting from lateral bending. At P less than 0.05, a laterally applied force causes less lateral displacement and lateral flexion, but more longitudinal displacement. Flexion and extension movements are not significantly altered after facetectomy.

Healing of experimentally produced lesions in articular cartilage following chondrocyte transplantation

Articular cartilage is known to have limited ability to heal once injured, and attempts to heal lesions in cartilage have yielded equivocal results. The following experiments were performed to investigate healing in cartilage transplantation of chondrocytes grown in vitro. The knee joint of the New Zealand White rabbit was used as the experimental model. An initial baseline study was made to determine the intrinsic capability of cartilage for healing defects that do not fracture the subchondral plate. A second experiment examined the effects of autologous in vitro grown chondrocytes on the healing rates of these defects. The results were evaluated by qualitative and quantitative light microscopy. In control defects not grafted with chondrocytes, 6 weeks after the initial defect was created, there was little repair. Macroscopic and histological findings were consistent with an osteoarthritic pathology such as synovitis and "cell nests." Macroscopic results from grafted specimens displayed a marked decrease in synovitis and other degenerative changes. Defects which had received transplants had a significant amount of cartilage reconstituted (82%) compared to ungrafted controls (18%). Controls showed a healing rate comparable to that obtained in the initial baseline study.

Do upper-body and centralized adiposity measure different aspects of regional body-fat distribution? Relationship to non-insulin-dependent diabetes mellitus, lipids, and lipoproteins

Both central and upper-body adiposity are associated with high rates of type II non-insulin-dependent diabetes mellitus (NIDDM), high triglyceride levels, and low high-density lipoprotein (HDL) cholesterol levels. Previous data have also suggested that central and upper-body adiposity are relatively uncorrelated and hence may measure different aspects of regional body fat distribution. We assessed body mass index (BMI), the ratio of subscapular-to-triceps skinfold (STR), the ratio of waist-to-hip circumference (WHR), lipids, lipoproteins, and glucose tolerance in 738 Mexican Americans (ages 25-64 yr), who participated in the San Antonio Heart Study, a population-based study of diabetes and cardiovascular risk factors. NIDDM was diagnosed according to National Diabetes Data Group criteria. In general, STR and WHR were associated with high NIDDM rates, low HDL cholesterol levels, and high triglyceride levels, although WHR was somewhat more predictive of these than STR. In females, BMI, WHR, and STR all made independent contributions to prediction of NIDDM and HDL cholesterol; in males, WHR and STR both made independent contributions to prediction of triglyceride levels. This suggests that both indices may measure different aspects of body-fat distribution. Investigators should consider measuring both of these indicators of body-fat distribution in studies of diabetes and other cardiovascular risk factors, although if only a single measure is feasible, WHR appears to be preferable.

Upper body and centralized adiposity in Mexican Americans and non-Hispanic whites: relationship to body mass index and other behavioral and demographic variables

Mexican Americans have a higher prevalence of NIDDM, more overall obesity and more centralized adiposity than non-Hispanic whites, but have thus far not been characterized as to whether they have greater upper body adiposity. Waist-to-hip circumferences (WHR, a measure of upper body adiposity) and subscapular-to-triceps skinfold ratios (centrality index, a measure of centralized adiposity) were determined in 725 Mexican Americans and 226 non-Hispanic whites as part of the San Antonio Heart Study, a population-based study of diabetes and cardiovascular risk factors. Mexican American females had higher centrality indices and WHRs than non-Hispanic white females, even after adjustment for demographic (age, menopausal status) and behavioral variables (body mass index, parity, cigarette smoking, alcohol consumption, exercise, and oral contraceptive and estrogen use). Mexican American males had higher centrality indices than non-Hispanic white males, but differences in WHR disappeared after adjustment for overall adiposity (body mass index). Of the demographic and behavioral variables, only age and body mass index were consistently related to regional body fat distribution. The lack of an association between body fat distribution and behavioral variables suggests that genetic factors may play the principal role in determining body fat distribution. Surprisingly, the distributions of centrality index and WHR were relatively independent of one another suggesting that they may be used as distinct, independent predictors of metabolic diseases.

Auditory biofeedback in spastic diplegia

Using a simple auditory feedback device that produces a continuous buzzing signal on heel contact, we studied the effects of augmented auditory biofeedback on the gait of four spastic diplegic children. The purpose of the biofeedback was to attempt to increase dorsiflexion at heel strike without causing other compensatory changes at the knee and hip, which might lead to crouch gait. We measured velocity, stride length, and thigh, knee, and ankle angles at the heel strike, midswing, and toe-off phases of gait. Four subjects, aged 5-8 years, were given a standard gait training program, supplemented with biofeedback two times per week in a clinical setting and 1 h daily in a home program over an 8-week period. Three computer video gait analyses of the sagittal plane were conducted without biofeedback in the pre- and posttraining conditions and twice with biofeedback over the course of treatment. We performed linear regression analysis of joint angles at heel strike, midswing, and toe-off as a function of days into the study for each patient. Angle-angle diagrams for a test subject before, during, and after treatment indicate changes toward a normal gait pattern with biofeedback. The linear regression analysis showed a statistically significant (p less than 0.01) shift toward dorsiflexion at heel strike with repeated exposure to biofeedback. A compensatory crouch gait was not induced. The linear regression analyses for hip and knee angles were not statistically significant (p greater than 0.25), indicating a disassociation of movement among hip, knee, and ankle.

Cervical facetectomy and its effect on spine strength

Fourteen cervical spine motion segments consisting of two adjacent vertebral bodies and their connecting ligaments were tested in shear. Five had intact facet joints, five had bilateral facetectomy of 50% or less, and four had bilateral 70% facetectomy. Three to 5 mm of root could be exposed in the specimens with 50% facetectomy, and 8 to 10 mm in those with 70% facetectomy. Anterior-posterior shear tests were run alternately in compression and distraction. Facetectomy was found to have no effect on compression and distraction stiffness. Failure in the 70% facetectomized specimens was due to fracture of the remaining joint at 159 lbs. In the specimens with 50% facetectomy, a fracture load could not be established since failure of the specimen mounting occurred at 208 lbs, as it did in two of the specimens without facetectomy that were tested to failure. The difference in bone fracture at 159 lbs and mounting failure at 208 lbs is significant at p less than 0.05. Bilateral resection of more than 50% of the facet joint significantly compromises the shear strength of a cervical spine motion segment.

A method of evaluating possible pin penetration in slipped capital femoral epiphysis using a cannulated internal fixation device

A technique that utilizes a newly designed cannulated screw with injection of radiographic dye through the screw cannula provides a reliable and practical method for detection and avoidance of pin penetration when operating on slipped capital femoral epiphyses. Adoption of this method minimizes the possibility of poor results occurring as a consequence of internal fixation.

The problem of evaluating in situ pinning of slipped capital femoral epiphysis: an experimental model and a review of 63 consecutive cases

Over a 3-year follow-up period, 63 hips (in 49 patients) that were pinned as treatment for slipped capital femoral epiphysis were examined and evaluated. A 36.8% incidence of unsuspected pin penetration was discovered. Four types of experimental models representing different degrees of severity of slipped capital femoral epiphysis were designed and manufactured in the bioengineering laboratory. In situ pinning was performed on each model. An extensive series of controlled test films on the models indicated the difficulty of accurately determining the true position of the pins with conventional roentgenographic views. Subsequent fluoroscopic analysis revealed a verifiable correlation between the limited visualization of conventional X-ray analysis following the pinning of a slipped capital femoral epiphysis and unrecognized pin penetration.