Can cross‐talk occur in human myelinated nerve fibers?

Introduction: The possibility that impulse cross‐talk can occur between myelinated human nerve fibers was explored. Methods: Instances of impulse conduction without decrement were found, and published recordings of compound action potentials of functionally homogeneous fibers were scrutinized. Results: Both analytical approaches yielded results consistent with cross‐talk occurring in some nerves after electrical stimulation. Conclusions: The possible ionic current paths in and out of neighboring fibers, which could be responsible for the phenomenon, have been considered in the light of seminal work on unmyelinated single axons. Muscle Nerve 54 : 361–365, 2016     

Can diffusion tensor imaging and tractography represent cross‐sectional area of lumbar multifidus in patients with LUMBAR spine disease?

Introduction: Cross‐sectional area (CSA) is a useful measurement to evaluate the lumbar multifidus, but it cannot reflect the morphological characteristics of the entire muscle. Recently, diffusion tensor imaging (DTI) and tractography (DTT) have been used to assess 3‐dimensional muscle structures both qualitatively and quantitatively. In this study we investigate the correlation between CSA and multifidus volume and the clinical utility of DTI and DTT. Methods: Twenty‐eight lumbar multifidi from 14 subjects with lumbar spine disease were analyzed. We conducted correlation analysis between CSA from conventional magnetic resonance images and DTI‐derived parameters, including muscle volume, fractional anisotropy (FA), and mean diffusivity (MD); we performed morphological assessment using DTT. Results: Multifidus volume had a strong positive correlation with CSA (r = 0.760, P < 0.001). Neither FA nor MD correlated with CSA. Multifidi spanning fewer vertebral segments were smaller in volume. Discussion: DTT can be a valuable tool to visualize and quantify the lumbar multifidus in lumbar spine disease. Muscle Nerve 57 : 200–205, 2018     

Is there a relationship between chocolate consumption and symptoms of depression? A cross‐sectional survey of 13,626 US adults

Objective: To examine associations between chocolate consumption and depressive symptoms in a large, representative sample of US adults. Methods: The data were from 13,626 adults (≥20 years) participating in the National Health and Nutrition Examination Survey between 2007–08 and 2013–14. Daily chocolate consumption was derived from two 24‐hr dietary recalls. Depressive symptoms were assessed using the Patient Health Questionnaire (PHQ‐9), with scores ≥10 indicating the presence of clinically relevant symptoms. We used multivariable logistic regression to test associations of chocolate consumption (no chocolate, non‐dark chocolate, dark chocolate) and amount of chocolate consumption (grams/day, in quartiles) with clinically relevant depressive symptoms. Adults with diabetes were excluded and models controlled for relevant sociodemographic, lifestyle, health‐related, and dietary covariates. Results: Overall, 11.1% of the population reported any chocolate consumption, with 1.4% reporting dark chocolate consumption. Although non‐dark chocolate consumption was not significantly associated with clinically relevant depressive symptoms, significantly lower odds of clinically relevant depressive symptoms (OR = 0.30, 95%CI 0.21–0.72) were observed among those who reported consuming dark chocolate. Analyses stratified by the amount of chocolate consumption showed participants reporting chocolate consumption in the highest quartile (104–454 g/day) had 57% lower odds of depressive symptoms than those who reported no chocolate consumption (OR = 0.43, 95%CI 0.19–0.96) after adjusting for dark chocolate consumption. Conclusions: These results provide some evidence that consumption of chocolate, particularly dark chocolate, may be associated with reduced odds of clinically relevant depressive symptoms. Further research capturing long‐term chocolate consumption and using a longitudinal design are required to confirm these findings and clarify the direction of causation.     

Is cold paresis related to axonal depolarization?

Cold paresis may occur in multifocal motor neuropathy and lower motor neuron disease. It was proposed to reflect nerve lesions where axons are depolarized due to loss of Na/K-pump activity. In those circumstances, a further decrease in pump activity by cooling may induce extra depolarization, conduction block, and weakness. Evidence for this hypothesis is incomplete because it is unknown if cold induces depolarization in human motor axons and other factors may contribute to the symptoms. To solve these questions, we examined 10 normal subjects. At 37, 25, 20, and 15°C we assessed: excitability in the median nerve, decrement on 3-Hz stimulation, pulsed Doppler of a wrist artery, and thenar muscle strength. Cooling induced: (1) findings compatible with axonal depolarization on excitability testing (fanning-in of threshold electrotonus, steepened current threshold relation, increased refractory period, decreased super- and subexcitability), (2) decreased Doppler peak systolic velocity without causing ischemia, (3) decreased muscle strength and impaired muscle relaxation. Decrement tests and compound muscle action potential amplitude remained normal. The excitability findings induced by cooling were best explained by axonal depolarization due to the effect of temperature on Na/K-pump activity. The induced weakness may be explained not only by this mechanism but also by impaired muscle contraction.     

Is depression related to subsequent diabetes mellitus?

OBJECTIVE: To compare the risk of developing diabetes mellitus (DM) in the general population between subjects who had a depression and subjects who never had a depression. METHOD: Retrospective cohort design. People with depression were diagnosed with a depression between 1975 and 1990; controls never had a depression. Both groups were followed for a diagnosis of type II diabetes until 2000. Data on 1334 depressed and 66 670 non-depressed subjects were available from a large general practice-based database. RESULTS: No overall relation was found, but among males below age 50 there was a 78% increase in the rate of development of DM compared with non-depressed patients (hazard ratio 1.78, 95% CI: 1.21-2.62). CONCLUSION: Depression in males between the age of 20 and 50 years is related to an increased risk of developing DM.     

Is the hippocampal theta rhythm related to cognition in a non‐locomotor place recognition task?

The possible correlation of 4-12 Hz hippocampal field oscillations (theta rhythm) with motor and cognitive behavior was studied by recording the hippocampal electroencephalogram in non-locomoting rats as they solved a hippocampus-dependent place recognition task. The electroencephalogram (EEG) during the place recognition task was compared with the EEG during a control task, which had the same motor demands but did not require place recognition. In the place recognition task, the rat was passively transported on the periphery of a circular rotating arena, operant responses (lever pressing in Experiment 1 and licking in Experiment 2) emitted in a 60 degrees reward sector of the arena trajectory were reinforced. As expected the theta rhythm was observed during "voluntary" movements such as walking and lever pressing. During walking and lever pressing, when prominent theta was observed, the frequency increased within the first 10 min of a session. When the rats were not moving, during licking or staying motionless, both the theta amplitude and frequency were lower compared with the EEG during walking. There were no correlations between any theta characteristics and cognitive demand of the tasks.     

Is there a relationship between elderly suicide rates and smoking? A cross‐national study

BACKGROUND: An independent relationship between smoking cigarettes and completed suicides has been reported in several cohort and case-control studies of younger subjects, but this relationship has rarely been examined in the elderly. METHODS: The relationship between the prevalence of smoking in males and females and suicide rates in males and females in the age-bands 65-74 years and 75 + years was examined using national-level aggregate data from the World Health Organisation and the United Nations Development Programme websites. In addition to univariate analysis, multivariate analysis were conducted to ascertain an independent relationship between the prevalence of smoking and elderly suicide rates. RESULTS: The main findings were: (i) on univariate analysis, the prevalence of smoking in males was positively correlated with suicide rates in males aged 65-74 years and males aged 75 + years, but this relationship was absent in females and (ii) on multivariate analysis there was no independent relationship between the prevalence of smoking in males and suicide rates in males in both the elderly age-bands. CONCLUSIONS: There is a case for examination of the relationship between smoking and elderly suicides in individual-level cohort or case-control studies because of the potential methodological difficulties in cross-national studies using national- level aggregate data, paucity of cohort or case-control studies at an individual-level in the elderly, and the observation of an independent relationship between smoking and completed suicides in individual-level cohort and case-control studies in younger age groups.     

Can general practice help address youth mental health? A retrospective cross‐sectional study in Dublin's south inner city

Aims: With general practice potentially having an important role in early intervention of mental and substance use disorders among young people, we aim to explore this issue by determining the prevalence of psychological problems and general practice/health service utilization among young people attending general practice. Methods: A retrospective cross‐sectional study of patients attending three general practices in Dublin city. Results: Among a sample of young people (mostly women, 44% general medical services (GMS) eligible), we observed considerable contact with general practice, both lifetime and for the 2 years of the study. The mean consultation rate was 3.9 consultations in 2 years and psychosocial issues (most commonly stress/anxiety and depression) were documented in 35% of cases. Identification of psychosocial issues was associated with GMS eligibility, three or more doctor consultations, and documentation of smoking and drinking status. Conclusions: Psychosocial issues are common among young people attending general practice and more work on their epidemiology and further identification in general practice are advocated.     

Is fear of pain related to placebo analgesia?

Objective

Verbal information that a painkiller has been administered generates an expectation of pain relief which in turn decreases pain. This expectation-based pain reduction is termed placebo analgesia. We hypothesized that fear of pain would be related to higher stress and pain intensity and to reduced placebo analgesia.

Methods

Sixty-three students (30 females) participated in a Two-Condition (placebo, natural history)×Five-Test (one pretest, four post-tests) within-subjects design. Heat pain was induced by a 30×30-mm contact thermode to the medial volar forearm. Each pain test lasted for 4 min at a temperature of 46°C. Stress, arousal, and pain intensity and pain unpleasantness were rated on 100-mm visual analogue scales.

Results

Fear of pain was related to higher anticipatory stress and to higher stress and pain intensity during pain. Fear of pain was also related to reduced placebo analgesic responding.

Conclusion

Fear of pain was positively related to stress both during pain and in the anticipation of pain, and negatively related to placebo analgesia. Previous research has indicated a role for increased stress in the nocebo response, and the present findings suggest that decreased stress may strengthen the placebo response.     

Is postmenopausal osteoporosis related to pineal gland functions?

There is currently considerable interest in the pathogenesis of postmenopausal osteoporosis, which is the most common metabolic bone disease. Osteoporosis affects approximately 20 million persons in the United States, 90% of whom are postmenopausal women. Although there is evidence that estrogen deficiency is an important contributory factor, the pathogenesis of osteoporosis is multifactorial and presently poorly understood. There is evidence that pineal melatonin is an anti-aging hormone and that the menopause is associated with a substantial decline in melatonin secretion and an increased rate of pineal calcification. Animal data indicate that pineal melatonin is involved in the regulation of calcium and phosphorus metabolism by stimulating the activity of the parathyroid glands and by inhibiting calcitonin release and inhibiting prostaglandin synthesis. Hence, the pineal gland may function as a "fine tuner" of calcium homeostasis. In the following communication, we propose that the fall of melatonin plasma levels during the early stage of menopause may be an important contributory factor in the development of postmenopausal osteoporosis. Consequently, plasma melatonin levels taken in the early menopause could be used as an indicator or perhaps as a marker for susceptibility to postmenopausal osteoporosis. Moreover, light therapy, administration of oral melatonin (2.5 mg at night) or agents which induce a sustained release of melatonin secretion such as 5-methoxypsoralen, could be useful agents in the prophylaxis and treatment of postmenopausal osteoporosis. Finally, since application of external artificial magnetic fields has been shown to synchronize melatonin secretion in experimental animals and humans, we propose that treatment with artificial magnetic fields may be beneficial for postmenopausal osteoporosis.