The moment arms of the muscles spanning the glenohumeral joint: a systematic review

The moment arm of a muscle represents its leverage or torque‐producing capacity, and is indicative of the role of the muscle in joint actuation. The objective of this study was to undertake a systematic review of the moment arms of the major muscles spanning the glenohumeral joint during abduction, flexion and axial rotation. Moment arm data for the deltoid, pectoralis major, latissimus dorsi, teres major, supraspinatus, infraspinatus, subscapularis and teres minor were reported when measured using the geometric and tendon excursion methods. The anterior and middle sub‐regions of the deltoid had the largest humeral elevator moment arm values of all muscles during coronal‐ and scapular‐plane abduction, as well as during flexion. The pectoralis major, latissimus dorsi and teres major had the largest depressor moment arms, with each of these muscles exhibiting prominent leverage in shoulder adduction, and the latissimus dorsi and teres major also in extension. The rotator cuff muscles had the largest axial rotation moment arms regardless of the axial position of the humerus. The supraspinatus had the most prominent elevator moment arms during early abduction in both the coronal and scapular planes as well as in flexion. This systematic review shows that the rotator cuff muscles function as humeral rotators and weak humeral depressors or elevators, while the three sub‐regions of the deltoid behave as substantial humeral elevators throughout the range of humeral motion. The pectoralis major, latissimus dorsi and teres major are significant shoulder depressors, particularly during abduction. This study provides muscle moment arm data on functionally relevant shoulder movements that are involved in tasks of daily living, including lifting and pushing. The results may be useful in quantifying shoulder muscle function during specific planes of movement, in designing and validating computational models of the shoulder, and in planning surgical procedures such as tendon transfer surgery.     

Health access and status of adolescents and young adults using youth employment and training programs in an urban environment.

PURPOSE: To describe the health status and access to healthcare of adolescents and young adults disconnected from traditional education and work settings. The health status of these disconnected youth is largely unknown, although it is suspected to be quite poor. Most information about the health of youth in the United States relies on school-based samples. METHOD: In-person interviews with 1037 adolescents and young adults (aged 16-24 years) enrolled in an employment and training program in Baltimore were used to measure access to health services and health status in four domains: violent behavior, mental health, substance use, and reproductive health. Differences in healthcare access and health status by age and gender were examined. In addition, youth in the employment and training sample are compared with Baltimore youth in school and of comparable ages, as measured by the Youth Risk Behavior Surveillance System. RESULTS: Nearly 50% of young adults in the employment and training program were found to lack health insurance, and about 20% reported a time when they needed medical care but did not receive it. Youth in the program exhibited notable health status concerns, often exceeding the risk prevalence of students in school. In particular, adolescents and young adults disconnected from traditional employment and work settings were more likely to be in physical fights, to smoke cigarettes, and to use marijuana than their in-school counterparts. In-school youth were more likely to have considered harming themselves and to have made a suicide plan in the last year. CONCLUSIONS: Given high levels of health risk among youth disconnected from traditional education and work settings, adolescent health providers must increasingly pay attention to integrating health promotion and disease prevention strategies into youth employment and training programs, where sizable numbers of these youth can be reached.     

Preliminary phylogenetic identification of virulent Chlamydophila pecorum strains

Chlamydophila pecorum is an obligate intracellular bacterium associated with different pathological conditions in ruminants, swine and koala, which is also found in the intestine of asymptomatic animals. A multi-virulence locus sequence typing (MVLST) system was developed using 19 C. pecorum strains (8 pathogenic and 11 non-pathogenic intestinal strains) isolated from ruminants of different geographical origins. To evaluate the ability of MVLST to distinguish the pathogenic from the non-pathogenic strains of C. pecorum, the sequences of 12 genes were analysed: 6 potential virulence genes (ompA, incA, incB, incC, mip and copN), 5 housekeeping genes (recA, hemD, aroC, efp, gap), and the ORF663 gene encoding a hypothetical protein (HP) that includes a variant 15-nucleotides coding tandem repeat (CTR). MVLST provided high discriminatory power (100%) in allowing to distinguish 6 of 8 pathogenic strains in a single group, and overall more discriminatory than MLST targeting housekeeping genes. ompA was the most polymorphic gene and the phylogenetic tree based only on its sequence differentiated 4 groups with high bootstrap values. The number of CTRs (rich in serine, proline and lysine) in ORF663 detected in the pathogenic strains was generally lower than that found in the intestinal strains. MVLST appears to be a promising method for the differential identification of virulent C. pecorum strains, and the ompA, incA and ORF663 genes appear to be good molecular markers for further epidemiological investigation of C. pecorum.     

Allergic reactions to isosulfan blue in sentinel lymph node mapping

BACKGROUND: Sentinel lymph node (SLN) biopsy is often used in the assessment of lymph node status in melanoma and early stage breast cancer. With the rapidly increasing use of the technique, we can now better characterize and assess the rate of adverse reactions to the dye. METHODS: A retrospective review of all patients undergoing SLN mapping at the Columbia-Presbyterian Breast Center were identified from June 2000 to July 2002. All patients who experienced allergic reactions were documented and records examined. RESULTS: In total, three out of 351 patients had allergic complications from the procedure. All three patients developed "blue hives" after injection with isosulfan blue. The incidence at our Breast Center was 0.9%. All were treated with intravenous corticosteroids and diphenhydramine and recovered within twenty-four hours. CONCLUSIONS: The increasing utilization of the sentinel lymph node technique will make these complications more common. A high index of suspicion and appropriate clinical management are recommended to minimize the potential morbidity of these reactions.     

Pulse oximeter changes with sentinel lymph node biopsy in breast cancer

HYPOTHESIS: The changes reported with pulse oximetry after the injection of isosulfan blue for sentinel lymph node identification in patients with breast cancer are consistent and predictable. DESIGN: Retrospective study. SETTING: University hospital. PATIENTS AND METHODS: The complete anesthesia records of 92 patients who underwent sentinel lymph node biopsy with intraparenchymal injection of isosulfan blue were reviewed. The study extended from January 1999 to February 2000. The operations were all performed after the patient received general anesthesia. We injected 5 mL of isosulfan blue into the breast tissue surrounding the tumor. The data reviewed included preinjection pulse oximeter saturation readings and postinjection values continuing until the readings returned to baseline levels in the postanesthesia care unit. MAIN OUTCOME MEASURES: Changes in oxygen saturation readings with the pulse oximeter before and after injection of isosulfan blue. RESULTS: Isosulfan blue injection interfered with pulse oximeter measurements for a substantial time-as much as 195 minutes. The mean time to the maximum change in the pulse oximeter reading was 35 minutes. The median decrease in oxygen saturation was 5%. The maximum decrease in the pulse oximeter reading was 11%. CONCLUSIONS: Although the changes in pulse oximeter readings can be substantial, their course appears to be predictable, and therefore in most otherwise healthy patients with normal pulmonary function, invasive monitoring is not necessary.     

Effects of raloxifene on bone metabolism and serum lipids in postmenopausal women on chronic hemodialysis

BACKGROUND: Premature amenorrhea and hypoestrogenism and lack of hormone replacement therapy after menopause have been frequently reported in uremic women on dialysis. Therefore, in addition to renal osteodystrophy, postmenopausal women on dialysis could be at risk of osteoporosis. In addition, these patients are at higher risk for hyperlipidemia, arteriosclerosis, and subsequent coronary heart disease and stroke. Recent evidence has suggested that hormone replacement therapy (HRT) in postmenopausal women could have several beneficial effects as well as potentially serious risks. Great efforts have been made to identify therapeutic alternatives that would have the benefits of estrogen on brain and bone without its adverse effects on breast and endometrium. In the present study, we evaluated the effect of raloxifene, a selective estrogen receptor modulator (SERM), on bone metabolism and serum lipids in postmenopausal women on chronic hemodialysis. METHODS: We performed a prospective, blind, placebo-controlled, and randomized study. Fifty postmenopausal women on chronic hemodialysis with proven severe osteopenia or osteoporosis by bone densitometry were selected. After a written informed consent, patients were randomized into two groups: 25 women on placebo and 25 women on the study drug, raloxifene hydrochloride, at a dose of 60 mg/day. In all patients, we performed a baseline bone mineral density (BMD) analysis and simultaneously evaluated different biochemical parameters, serum lipids (total low-density lipoprotein [LDL] and high-density lipoprotein [HDL] cholesterol and triglycerides) and serum markers of bone resorption (pyridinoline crosslinks). BMD was reassessed after 1 year of therapy. Bone resorption markers were determined every 3 months for 1 year. RESULTS: After 1 year on raloxifene therapy, lumbar spine BMD (trabecular bone) significantly improved, whereas femoral neck BMD (cortical bone) did not change significantly. No changes in BMD were observed at trabecular or cortical sites in the placebo group. Serum pyridinoline levels showed a significant decrease after 6 months on raloxifene that persisted thereafter. Low-density lipoprotein (LDL)-cholesterol decreased significantly in the raloxifene group with no changes in serum triglycerides, total cholesterol, or HDL cholesterol. No significant side effects were observed in the raloxifene group. CONCLUSION: The study demonstrates that after one year on raloxifene, postmenopausal women on hemodialysis have a significant increase in trabecular BMD, decrease in bone resorption markers and LDL-cholesterol values, suggesting that SERMs could constitute a therapeutic alternative to improve bone metabolism and control of hyperlipidemia in these patients. The possible long-term effects of raloxifene remain to be determined.     

Neurobehavioral performance and work experience in Florida farmworkers

Farmworkers experience many work-related hazards, including exposure to neurotoxicants. We compared neurobehavioral performance of 288 farmworkers in central Florida who had done farm work for at least 1 month with 51 controls who had not. Most of the farmworkers had worked in one or more of three types of agriculture: ornamental ferns, nurseries, or citrus fruit. We collected information on farm work history in a structured interview and evaluated neurobehavioral performance using a battery of eight tests. Analyses were adjusted for established confounders including age, sex, education, and acculturation. Ever having done farm work was associated with poor performance on four tests--digit span [odds ratio (OR) = 1.90; 95% confidence interval (CI), 1.02-3.53], tapping (coefficient = 4.13; 95% CI, 0.00-8.27), Santa Ana test (coefficient = 1.34; 95% CI, 0.29-2.39), and postural sway (coefficient = 4.74; 95% CI, -2.20 to 11.7)--but had little effect on four others: symbol digit latency, vibrotactile threshold, visual contrast sensitivity, and grip strength. Associations with farm work were similar in magnitude to associations with personal characteristics such as age and sex. Longer duration of farm work was associated with worse performance. Associations with fern work were more consistent than associations with nursery or citrus work. Deficits related to the duration of work experience were seen in former as well as current farmworkers, and decreased performance was related to chronic exposure even in the absence of a history of pesticide poisoning. We conclude that long-term experience of farm work is associated with measurable deficits in cognitive and psychomotor function.     

The Long Island Breast Cancer Study Project: description of a multi-institutional collaboration to identify environmental risk factors for breast cancer

The Long Island Breast Cancer Study Project is a federally mandated, population-based case-control study to determine whether breast cancer risk among women in the counties of Nassau and Suffolk, NY, is associated with selected environmental exposures, assessed by blood samples, self-reports, and environmental home samples. This report describes the collaborative project's background, rationale, methods, participation rates, and distributions of known risk factors for breast cancer by case-control status, by blood donation, and by availability of environmental home samples. Interview response rates among eligible cases and controls were 82.1% (n = 1,508) and 62.8% (n = 1,556), respectively. Among case and control respondents who completed the interviewer-administered questionnaire, 98.2 and 97.6% self-completed the food frequency questionnaire; 73.0 and 73.3% donated a blood sample; and 93.0 and 83.3% donated a urine sample. Among a random sample of case and control respondents who are long-term residents, samples of dust (83.6 and 83.0%); soil (93.5 and 89.7%); and water (94.3 and 93.9%) were collected. Established risk factors for breast cancer that were found to increase risk among Long Island women include lower parity, late age at first birth, little or no breast feeding, and family history of breast cancer. Factors that were found to be associated with a decreased likelihood that a respondent would donate blood include increasing age and past smoking; factors associated with an increased probability include white or other race, alcohol use, ever breastfed, ever use of hormone replacement therapy, ever use of oral contraceptives, and ever had a mammogram. Long-term residents (defined as 15+ years in the interview home) with environmental home samples did not differ from other long-term residents, although there were a number of differences in risk factor distributions between long-term residents and other participants, as anticipated.     

Factors Correlating With Lymph Node Metastases in Patients With T1 Breast Cancer

Background: Identification of reliable predictors of axillary metastases (ALNM) may be useful in selecting appropriate management for patients with T1-size breast cancer. This study was undertaken to determine the degree of correlation between ALNM and several variables, including age, race, menopausal status, palpability, tumor size, positive margin on initial excision, histology, grade, lymphatic invasion (LI), estrogen receptor status (ER), progesterone receptor status, S-phase, and ploidy.Methods: Data from 1416 patients with T1 breast cancers treated at Columbia-Presbyterian Medical Center between 1989 and 1998 was reviewed. Patients with multifocal tumors were excluded.Results: Mean patient age was 57.5 years (SD = 12.0); 65% of the patients were postmenopausal. One hundred thirty-one patients with T1a (0.5 cm), 435 with T1b (0.6–1.0 cm), and 850 patients with T1c (1.1–2.0 cm) lesions were studied. The overall rate of ALNM was 23%. AM was identified in 11% of T1a, 15% of T1b, and 29% of T1c patients. Statistically significant factors from univariate analysis were age, palpability, skin changes, tumor size, LI, histology, grade, ER status, and positive margin on initial excision.Conclusions: Axillary staging by either sentinel lymph node biopsy or level I/II axillary dissection is indicated for most T1 breast cancer patients. Omission of axillary staging can be considered for highly selected patients with T1a cancers.