Human masticatory muscle forces during static biting

Muscle forces determine joint loads, but the objectives governing the mix of muscle forces involved are unknown. This study tested the hypothesis that masticatory muscle forces exerted during static biting are consistent with objectives of minimization of joint loads (MJL) or muscle effort (MME). To do this, we compared numerical model predictions with data measured from six subjects. Biting tasks which produced moments on molar and incisor teeth were modeled based on MJL or MME. The slope of predicted vs. electromyographic (EMG) data for an individual was compared with a perfect match slope of 1.00. Predictions based on MME matched best with EMG activity for molar biting (slopes, 0.89-1.16). Predictions from either or both models matched EMG results for incisor biting (best-match slopes, 0.95-1.07). Muscle forces during isometric biting appear to be consistent with objectives of MJL or MME, depending on the individual, biting location, and moment.     

Proxy validation of patient self-reports of ADL and IADL function before and after electroconvulsive therapy

OBJECTIVE: To determine whether electroconvulsive therapy (ECT) patients' self-reported functional status is similar to that reported by a proxy. BACKGROUND: Increasing levels of depression are associated with deteriorating functional status as reflected in the Instrumental Activities of Daily Living (IADL) scale. Depressed patients referred for ECT have poorer IADL status compared with depressed patients receiving medications, suggesting that IADL status may shape physicians' decision to recommend ECT ( 1). Further, IADL status improves with treatment of depression, both in ECT-and medication-treated patients. Given the potential importance of IADL status for ECT patients, we examined whether IADL status as reported by patients prior to ECT was comparable to IADL status as described by a proxy. DESIGN/METHODS: Forty depressed patients (23 men and 17 women, mean age 58.1 +/- 17.5) were each interviewed alone with the 21-item Hamilton Depression Rating Scale (HDRS), Mini-Mental State Exam (MMSE), an Activities of Daily Living (ADL) scale, and an IADL scale. We then privately interviewed a first-degree relative who lived with each patient and recorded their impression of the patient's ADL and IADL function before ECT, and at 2 and 4 weeks after ECT. RESULTS: baseline scores for HDRS and MMSE were consistent with a severe level of depressive symptoms and intact global cognitive function. Patients' and proxies' IADL scores were highly correlated before ECT, 2 weeks after ECT, and 4 weeks after ECT. Significant, but slightly weaker correlations were seen for ADL scores. CONCLUSIONS: Ideally, ADL and IADL function would be measured by direct observation rather than either patient or proxy report. At this time it is unknown whether the patient or the proxy report should be considered the "gold standard." In this study, the patients' self-reported functional scores were highly correlated with the proxies' scores. We conclude that patients' reports of their function are roughly comparable to proxies' impressions before and after ECT.     

The prevalence of major depression or dysthymia among aged Medicare Fee-for-Service beneficiaries

RESEARCH OBJECTIVE: Estimates of the prevalence of major depression vary widely. Current estimates range from 2 to 14 % depending upon the definition and procedure for diagnosis. Further, most estimates are for special populations, either living in selected geographic areas or receiving specific types of medical care. A national survey of Medicare Fee-for-Service (FFS) beneficiaries provides an opportunity to assess the current level of major depression or dysthymia among a diverse population of older Americans. STUDY DESIGN: The Health Outcomes Survey (HOS) was administered to a national random sample of 1,000 Medicare FFS beneficiaries. We used the Mental Component Summary (MCS) measure of the SF-36 to estimate the prevalence of major depression or dysthymia. Logistic regression was used to examine associated factors. RESULTS: The response rate was 61.7%. Using an MCS score of 42 or lower, prevalence of major depression or dysthymia was estimated to be 25% for respondents age 65 years and older. Logistic regression analysis revealed that the likelihood of major depression or dysthymia was associated with years of education (Odds Ratio (OR) = 0.87), difficulties performing activities of daily living (OR = 1.72), and Medicaid enrollment (OR = 2.67). CONCLUSIONS: The results revealed that one-quarter of the respondents reported mental health problems consistent with major depression or dysthymia. This is higher than previously reported. Like previous studies, years of education, physical impairment, and poverty are strong predictors of major depression or dysthymia. The high rate of major depression or dysthymia implies there may be considerable unmet need among elderly Medicare FFS beneficiaries for diagnosing and treating mental illness.     

Outbreak of pertussis among healthcare workers in a hospital surgical unit.

BACKGROUND: In September 1999, a pertussis outbreak was detected among surgical staff of a 138-bed community hospital. Patients were exposed to Bordetella pertussis during the 3-month outbreak period. OBJECTIVE: To describe the outbreak among surgical staff, to evaluate implemented control measures, and to determine whether nosocomial transmission occurred. METHODS: Clinical pertussis was defined as acute cough illness with a duration of 14 days or more without another apparent cause; persons with positive culture, PCR, or serologic test results were defined as having laboratory-confirmed pertussis. Surgical healthcare workers (HCWs) were interviewed regarding pertussis symptoms, and specimens were obtained for laboratory analysis. Patients exposed to B. pertussis during an ill staff member's 3-week infectious period were interviewed by phone to determine the extent of nosocomial spread. PARTICIPANTS: A total of 53 HCWs assigned to the surgical unit and 146 exposed patients. HCWs with pertussis were defined as case subjects; HCWs without pertussis were defined as non-case subjects. RESULTS: Twelve (23%) of 53 HCWs had clinical pertussis; 6 cases were laboratory confirmed. The median cough duration in the 12 case subjects was 27 days (range, 20-120 days); 10 (83%) had paroxysms. Eleven (92%) of 12 case subjects and 28 (86%) of 41 non-case subjects received antibiotic treatment or prophylaxis. Seven case subjects (58%) reported they always wore a mask when near patients. Of 146 patients potentially exposed to pertussis from the 12 case subjects, 120 (82%) were interviewed; none reported a pertussis-like illness. CONCLUSIONS: Surgical staff transmitted B. pertussis among themselves; self-reported data suggests that these HCWs did not transmit B. pertussis to their patients, likely because of mask use, cough etiquette, and limited face-to-face contact. Control measures might have helped limit the outbreak once pertussis was recognized.     

MRI detection of unsuspected vertebral injury in acute spinal trauma: incidence and significance

Objective. Multilevel spinal injury is well recognised. Previous studies reviewing the radiographs of spinal injury patients have shown an incidence of 15.2% of unsuspected spinal injury. It is recognised that magnetic resonance imaging (MRI) can identify injuries that are not demonstrated on radiographs. The objective of this study was to determine the incidence and significance of spinal injuries using MRI in comparison with radiographs. Design and patients. The radiographs and MR images of 110 acute spinal injury patients were reviewed independently of each other and the findings were then correlated to determine any unsuspected injury. Results. MRI detected vertebral body bone bruises (microtrabecular bone injury) in 41.8% of spinal injury patients which were not seen on radiographs. These bone bruises were best appreciated on sagittal short tau inversion recovery MR sequences and seen at contiguous and non-contiguous levels in relation to the primary injury. Conclusion. This level of incidence of bone bruises has not previously been appreciated. We recommend that patients undergoing MRI for an injured segment of the spine are better assessed by MRI of the entire spine at the same time to exclude further injury. Received: 17 April 2000 Revision requested: 19 June 2000 Revision received: 6 September 2000 Accepted: 27 November 2000     

Effect of adenosine and pertussis vaccine on lymphocyte response in vitro to phytohemagglutinin in asthmatic and non-asthmatic subjects

Adenosine and pertussis vaccine each significantly suppressed the in vitro lymphocyte response to phytohemagglutinin (PHA) in both asthmatic and non-asthmatic subjects. On the other hand, pertussis vaccine significantly enhanced the response of the lymphocytes treated with a lower concentration of adenosine both in asthmatic and non-asthmatic subjects. It was also shown that lymphocytes from asthmatic and non-asthmatic subjects responded similarly to the modulating effect of adenosine and/or pertussis vaccine on PHA stimulation. These data give further evidence for the complex interplay of the vaccine with endogenous adenosine.     

Creatine phosphokinase activity in rabbit alveolar macrophages

An enzyme is present in extracts of rabbit alveolar macrophage which can catalyze the reaction of creatine phosphate with adenosine diphosphate to form adenosine triphosphate and creatine. The enzyme is moderately activated by reduced glutathione, has a pH optimum between pH 6.5 and 7.0, and shows an absolute requirement for Mg(2+). The K(m) for creatine phosphate is approximately 3.6 mm while the K(m) for adenosine diphosphate is about 1.1 mm. The enzyme may play a role in the energy balance of the cell by creating a reserve of energy in the form of creatine phosphate.