Motor unit firing behavior in human arm flexor muscles during sinusoidal isometric contractions and movements

Simultaneous recordings of action potentials (APs) of multiple single motor units (MUs) were obtained in brachialis and biceps (caput breve) muscles during sinusoidally modulated isometric contractions of elbow flexor muscles and during sinusoidal flexion/extension movements in the elbow against a preload in the extension direction. The results show that MUs typically fire in one short burst for each sinusoidal cycle. The mean phase lead of the bursts of APs relative to a sinusoidally modulated isometric torque in the elbow joint or relative to sinusoidal movements in the elbow increases gradually with frequency. The increase of the mean phase lead during isometric contractions was very similar for all MUs and could be explained well by modeling the force production of MUs with a second-order linear low-pass system. For sinusoidal flexion/extension movements each MU reveals a specific, reproducible phase lead as a function of frequency. However, there is a large variability in phase behavior between MUs. Also, the modulation of the firing rate for sinusoidal isometric contractions versus sinusoidal movements appeared to be different for various MUs. In simultaneous recordings some MUs clearly revealed a larger firing rate in each burst for movements relative to isometric contractions, whereas other MUs revealed a smaller firing rate. This suggests that some MUs are preferentially activated during movements whereas others are preferably activated during isometric contractions. The results demonstrate task-dependent changes in the relative activation of MUs within a single muscle for sinusoidal isometric contractions and movements. Received: 18 November 1996 / Accepted: 3 April 1997     

Validation of preimplantation genetic diagnosis by PCR analysis: genotype comparison of the blastomere and corresponding embryo, implications for clinical practice

The aim of this study was to validate the overall preimplantation genetic diagnosis (PGD)-PCR procedure and to determine the diagnostic value. Genotyped embryos not selected for embryo transfer (ET) and unsuitable for cryopreservation after PGD were used for confirmatory analysis. The PGD genotyped blastomeres and corresponding embryos were compared, and morphology was scored on Day 4 post fertilization. To establish the validity of the PGD-PCR procedure and the diagnostic value, misdiagnosis rate, false-negative rate and negative predictive value were calculated. Moreover, comparison on the validity was made for the biopsy of one or two blastomeres. For the total embryo group (n = 422), a misdiagnosis rate of 7.1% and a false-negative rate of 3.1% were found. The negative predictive value was 96.1%. Poor morphology Day 4 embryos (Class 1) were over-represented in the embryo group in which the blastomere genotype was not confirmed by the whole embryo genotype. The misdiagnosis rate of Class 1 embryos was 12.5% and the false-negative rate 17.1%. Exclusion of these embryos resulted in a misdiagnosis rate of 6.1%, a false-negative rate of 0.5% and a negative predictive value of 99.3%. The two blastomere biopsies revealed a significant higher positive predictive value, lowering the misdiagnosis rate, whereas the negative predictive value remained the same. In conclusion, the PGD-PCR procedure is a valid diagnostic method to select unaffected embryos for ET. The misdiagnosis and false-negative rates decrease by rejecting Class 1 embryos for ET. The biopsy of a second blastomere improves the positive predictive value, lowering the misdiagnosis rate.     

Three-dimensional head and upper arm orientations during kinematically redundant movements and at rest

The three rotational degrees of freedom of the head and the upper arm exceed the number needed in a two-dimensional (2-D) facing or pointing task, respectively. Previous studies reported a reduction of the number of degrees of freedom from three to two, with one degree of freedom being a unique function of the other two (Donders' law). This study investigated whether three-dimensional (3-D) orientations of the head and arm are the same at rest and during movement for corresponding pointing or facing directions. Two separate experiments were performed: one focused on head orientations, the other focused on upper arm orientations. We instructed subjects to direct the nose or to point the extended arm in the direction of targets, which appeared in a quasi-random order at 2-s intervals. The head and upper arm orientations at rest were described by a 2-D surface with a scatter less than 3 or 4 degrees, respectively. Both for the arm and the head, orientations started and ended near the 2-D surface, but for a number of the target pairs, the orientations deviated from those predicted by the 2-D surface during movement in a way that was consistent and reproducible for movements between each target pair. For upper arm movements, we often found that deviations of arm orientations from the 2-D surface increased with increasing movement velocity. Such a positive correlation between deviation and movement velocity was not found for head movements. These results clearly indicate violations of Donders' law during movement and argue against several models for movement control found in the literature.     

Non-linear increase in vertebral density induced by a synthetic steroid (Org OD 14) in women with established osteoporosis

The results of a 2-year placebo-controlled study in 38 female patients with osteoporosis are presented. This study was conducted to evaluate the efficacy of a daily oral dose of 2.5 mg Org OD 14 ((7 alpha, 17 alpha)-17-hydroxy-7-methyl-19-norpregn-5(10)-en-20-yn-3-one) in the treatment of established osteoporosis. Org OD 14 is a steroid which shows combined weak oestrogenic, androgenic and progestational activity. A total of 31 patients completed a 12-month study period (17 placebo, 14 Org OD 14) and 25 of these went on to complete the full 24-months (15 placebo, 10 Org OD 14). A significant increase in bone mineral density as measured by dual photon absorptiometry was recorded in the lumbar spine in the Org OD 14-treated patients at 8, 16 and 24 months. The gain in bone mass after 8 months averaged 4% (P less than 0.01) and after 24 months 8% (P less than 0.001). In the control group, a bone loss rate of 2% per year was recorded in the lumbar spine. No significant changes in bone density in the forearm as assessed by single photon absorptiometry were found in either group. The increase in spinal bone density in the Org OD 14 group was non-linear and followed an S-shaped upward pattern. Org OD 14, while inducing no appreciable endometrial stimulation, was found to be a bone-active compound with anti-resorbing as well as anabolic activity. Org OD 14 warrants consideration not only for the long-term prevention of bone loss but also for curative treatment of post-menopausal osteoporosis.     

Women's Lives After an HIV-Positive Diagnosis: Disclosure and Violence

Objectives: This research addresses four questions: (1) What role do health care providers play in women's disclosure to others of their HIV-positive status? (2) What are women's concerns and experiences with disclosure? (3) What violence do women living with HIV experience? (4) How is the violence related to their diagnosis and disclosures? Methods: Participants were 310 HIV-positive women enrolled in an HIV primary care clinic in an urban teaching hospital. Women were interviewed once using both quantitative and qualitative methods. Results: Women had known they were HIV-positive for an average of 5.8 years; 22% had an HIV-positive partner; 58% had disclosed their status to more than 10 people; and 68% had experienced physical abuse and 32% sexual abuse as an adult. Fifty-seven percent of the sample reported that a health care provider had told them to disclose to their sex partners. Women who were afraid of disclosure-related violence (29%) were significantly more likely than those who were not to report that a health care provider helped them with disclosure (21% vs. 10%). Although 4% reported physical abuse following a disclosure event, 45% reported experiencing emotional, physical, or sexual abuse at some time after their diagnosis. Risk factors for experiencing abuse after diagnosis were a prior history of abuse, drug use, less income, younger age, length of time since diagnosis, and having a partner whose HIV status was negative or unknown. Conclusions: Identifying women at risk for abuse after an HIV-positive diagnosis is important for those who provide HIV testing and care. Routine screening for interpersonal violence should be incorporated into HIV posttest counseling and continuing primary care services.

     

Women living with HIV: Disclosure, violence, and social support

This paper describes the frequency of women's disclosure of their HIV status, examines the extent to which they experience adverse social and physical consequences when others learn they are infected, and analyzes correlates of these negative outcomes. There were 257 HIV-positive women between the ages of 18 and 44, recruited from HIV/AIDS primary care clinics and from community sites, who completed a face-to-face interview. Women in the sample were 33 years old on average; 92% were African-American; 54% had less than 12 years of education; 56% had used intravenous drugs; and 30% knew they were HIV positive for 5 or more years. There were 97% who disclosed their HIV status; 64% told more than 5 people. Negative consequences associated with others knowing they were HIV-positive were reported by 44%, most commonly the loss of friends (24%), being insulted or sworn at (23%), and being rejected by family (21%). There were 10 women (4%) who reported being physically or sexually assaulted as a result of their being HIV positive, and 16% reported having no one they could count on for money or a place to stay. Violence was widespread in this sample, with 62% having experienced physical or sexual violence, including sexual abuse or rape (27%), being beaten up (34%), and weapon-related violence (26%). Logistic regression analysis indicated that women with a history of physical and sexual violence were significantly more likely to experience negative social and physical consequences when their infection became known to others, adjusting for age and the number of people women had disclosed to, both of which were only marginally significant. Partner notification policies and support programs must be responsive to the potential negative consequences associated with others learning that a woman is HIV positive. The high rates of historical violence in the lives of women living with HIV underscore the need for routine screening and intervention for domestic violence in all settings that provide health care to HIV-positive women.     

Women's opinions about domestic violence screening and mandatory reporting

BACKGROUND: The purpose of this paper is to describe women's opinions and policy preferences concerning domestic violence screening and mandatory reporting. METHODS: This case-control study included 202 abused women and 240 randomly selected non-abused women recruited from a large metropolitan health maintenance organization who were interviewed by telephone. Of these women, 46.6% had a college degree, 53.4% were white, and 60% had a household income of $50,000 or more. RESULTS: Forty-eight percent of the sample agreed that health care providers should routinely screen all women, with abused women 1.5 times more likely than non-abused women to support this policy. For mandatory reporting, 48% preferred that it be the woman's decision to report abuse to the police. Women thought it would be easier for abused women to get help with routine screening (86%) and mandatory reporting (73%), although concerns were raised about increased risk of abuse with both screening (43%) and reporting (52%) policies. Two thirds of the sample thought women would be less likely to tell their health care providers about abuse under a mandatory reporting policy. Interventions offered in managed care settings that would be well received, according to the women in this study, include counseling services, shelters, and confidential hotlines. CONCLUSIONS: Women expressed fears and concerns about negative consequences of routine screening and, even more so, for mandatory reporting. Domestic violence policies and protocols need to address the safety, autonomy, and confidentiality issues that concern women.     

Women’s opinions about domestic violence screening and mandatory reporting

Background: The purpose of this paper is to describe women’s opinions and policy preferences concerning domestic violence screening and mandatory reporting.Methods: This case–control study included 202 abused women and 240 randomly selected non-abused women recruited from a large metropolitan health maintenance organization who were interviewed by telephone. Of these women, 46.6% had a college degree, 53.4% were white, and 60% had a household income of $50,000 or more.Results: Forty-eight percent of the sample agreed that health care providers should routinely screen all women, with abused women 1.5 times more likely than non-abused women to support this policy. For mandatory reporting, 48% preferred that it be the woman’s decision to report abuse to the police. Women thought it would be easier for abused women to get help with routine screening (86%) and mandatory reporting (73%), although concerns were raised about increased risk of abuse with both screening (43%) and reporting (52%) policies. Two thirds of the sample thought women would be less likely to tell their health care providers about abuse under a mandatory reporting policy. Interventions offered in managed care settings that would be well received, according to the women in this study, include counseling services, shelters, and confidential hotlines.Conclusions: Women expressed fears and concerns about negative consequences of routine screening and, even more so, for mandatory reporting. Domestic violence policies and protocols need to address the safety, autonomy, and confidentiality issues that concern women.     

Evaluation of cognitive subdomains, 25-hydroxyvitamin D,and 1,25-dihydroxyvitamin D in the European Male Ageing Study

Purpose

Although lower levels of vitamin D have been related to poor cognitive functioning and dementia in older adults, evidence from longitudinal investigations is inconsistent. The objective of this study was to determine whether 25-hydroxyvitamin D [25(OH)D] and 1,25-dihydroxyvitamin D [1,25(OH)₂D] levels are associated with specified measures of cognitive decline in ageing men.

Methods

The European Male Ageing Study (EMAS) followed 3369 men aged 40–79 over 4.4 years. 25(OH)D levels at baseline were measured by radioimmunoassay, and 1,25(OH)₂D levels were obtained with liquid chromatography–tandem mass spectrometry. Visuoconstructional abilities, visual memory, and processing speed at baseline and follow-up were assessed using the Rey–Osterrieth Complex Figure Test (ROCF), Camden Topographical Recognition Memory (CTRM), and the Digit Symbol Substitution Test (DSST).

Results

Following attritions, a total of 2430 men with a mean (SD) age of 59.0 (10.6) were included in the analyses. At baseline, the mean 25(OH)D concentration was 64.6 (31.5) nmol/l, and mean 1,25(OH)₂D level was 59.6 (16.6) pmol/l. In age-adjusted linear regression models, high 25(OH)D concentrations were associated with a smaller decline in the DSST (β = 0.007, p = 0.020). Men with low 25(OH)D levels (<50 nmol/l) showed a greater decline in the CTRM compared to men with higher (≥75 nmol/l) levels (β = ?0.41, p = 0.035). However, these associations disappeared after adjusting for confounders such as depressive symptoms, BMI, and comorbidities. There was no indication of a relationship between 1,25(OH)₂D and decline in cognitive subdomains.

Conclusion

We found no evidence for an independent association between 25(OH)D or 1,25(OH)₂D levels and visuoconstructional abilities, visual memory, or processing speed over on average 4.4 years in this sample of middle-aged and elderly European men.