Exercise-induced hypercalcemia and vasopressin-mediated bone resorption

Our human observational study showed that elevated arginine vasopressin levels by heavy exercise, not catecholamines, were associated with elevated serum tartrate-resistant acid phosphatase 5b (TRACP-5b). The increase in serum calcium was positively associated with percent changes of TRACP-5b, implying the involvement of bone resorption in the pathogenesis of exercise-induced hypercalcemia.

INTRODUCTION

It remains unclear whether enhanced bone resorption explains exercise-induced hypercalcemia. An experimental study demonstrated that arginine vasopressin (AVP) stimulated osteoclast activity.

METHODS

We conducted a prospective observational study, enrolling 65 trained healthy male officers of the Japan Self-Defense Forces (34 and 31 in waves 1 and 2, respectively). Before and after a 5-h heavy exercise, we collected laboratory data including bone markers, symptoms, and ionized calcium (iCa; wave 2 only). As blood calcium levels change after exercise, we estimated calcium (corrected calcium) levels immediately after the exercise using the correlation between blood calcium and time from the end of exercise in another cohort.

RESULTS

Body weight decreased by 6.9% after the exercise. Corrected post-exercise serum total calcium (tCa) and iCa levels were significantly higher than pre-exercise levels, and 18% of participants showed hypercalcemia defined as corrected tCa >10.4 mg/dL or iCa >1.30 mmol/L. Serum tartrate-resistant acid phosphatase 5b (TRACP-5b), plasma three fractions of catecholamines, and AVP elevated significantly (median 14.3 pg/mL), while procollagen type 1 N-terminal propeptide and whole parathyroid hormone showed significant decreases. Corrected tCa increase showed a non-linear positive association with percent changes of TRACP-5b (%ΔTRACP-5b) even after adjustment for confounders. In addition, %ΔTRACP-5b was not associated with catecholamines, but with post-exercise AVP levels after adjustment for pre-exercise TRACP-5b. Symptoms of nausea or vomiting (observed in 20%) were positively associated with corrected post-exercise iCa after adjustment for post-exercise blood pH.

CONCLUSION

AVP elevation may explain bone resorption and the following hypercalcemia in the setting of heavy exercise.

Preferences for health information in middle-aged Japanese workers based on health literacy levels: a descriptive study

OBJECTIVES

To describe the health information preferences in middle-aged Japanese workers based on health literacy (HL) levels and presence of medications.

STUDY DESIGN

A cross-sectional study.

METHODS

We performed a web-based questionnaire survey with Japanese workers aged below 60 years. HL was assessed using the total score of communicative skills (five items) and critical skills (four items) from the 14-item Health Literacy Scale. Regarding their health information preferences, participants were asked about the health information they wanted (four items), could easily understand (six items), or easily use (two items) and answered on a 4-point scale (strongly agree/agree/disagree/strongly disagree). The percentages of the affirmative responses (strongly agree or agree) were compared among tertiles based on the HL score.

RESULTS

We obtained data from a total of 3387 volunteers, of whom 510 participants were on either antihypertensive, lipid-lowering, or antidiabetic drugs. Compared with the high HL and middle HL groups, low HL had fewer affirmative responses to most health information items. Health information items received 70% of affirmative responses even in the low HL level. They were visually shown by figures or pictures, highlighted by colors for important points, could be read in 1-2 min, and were accessed on the Internet, regardless of the presence of medications. Additionally, the explanation for mechanisms of medications or lifestyle to prevent or improve diseases showed high affinity in all HL levels, only for those on medications.

CONCLUSIONS

This result generates a hypothesis that low HL individuals have a low interest in health information. Our data showed several possible forms of health information with high affinity based on HL levels that would help plan future population approaches.

Peripheral administration of κ-opioid receptor antagonist stimulates gonadotropin-releasing hormone pulse generator activity in ovariectomized, estrogen-treated female goats

Pulsatile gonadotropin-releasing hormone (GnRH) secretion is indispensable for reproduction in mammals. Kisspeptin neurons in the hypothalamic arcuate nucleus (ARC), referred to as KNDy neurons because of the coexpression of neurokinin B and dynorphin A, are considered as components of the GnRH pulse generator that produces rhythmic GnRH secretion. The present study aimed to investigate if peripheral administration of PF-4455242, a κ-opioid receptor (KOR, a dynorphin A receptor) antagonist, facilitates pulsatile luteinizing hormone (LH) secretion and GnRH pulse generator activity in estrogen-treated ovariectomized Shiba goats to determine the possibility of using KOR antagonists to artificially control ovarian activities. PF-4455242 was intravenously infused for 4 h (1 or 10 μmol/kg body weight/4 h) or as a single subcutaneous injection (1 or 10 μmol/kg body weight). In a separate experiment, the same KOR antagonist (10 μmol/kg body weight/4 h) was intravenously infused during the recording of multiple unit activity (MUA) in the ARC that reflects the activity of the GnRH pulse generator to test the effects of KOR antagonist administration on GnRH pulse generator activity. Intravenous infusion and single subcutaneous injection of the KOR antagonist significantly increased the frequency of LH pulses compared with controls. Intravenous infusion of KOR antagonist also significantly increased the frequency of episodic bursts in the MUA. The present study demonstrates that peripherally administered KOR antagonist stimulates pulsatile LH secretion by acting on the GnRH pulse generator, and peripheral administration of PF-4455242 can be used to facilitate pulsatile LH secretion, which in turn facilitates ovarian activities in farm animals.

The effect of bolus volume on laryngeal closure and UES opening in swallowing: Kinematic analysis using 320-row area detector CT study

This study investigated the effects of three different volumes of honey-thick liquid on the temporal characteristics of swallowing. Twenty-six healthy subjects (15 males, 11 females) underwent 320-row area detector CT scan while swallowing 3, 10 and 20 mL of honey-thick liquid barium. Three-dimensional images were created at 10 images/s. Kinematic events involving six structures (velopharynx, hyoid bone, epiglottis, laryngeal vestibule (LV), true vocal cords (TVC), upper esophageal sphincter (UES)) and timing of bolus movement were timed using frame by frame analysis. The overall sequence of events did not differ across three volumes; however, increasing bolus volume significantly changed the onset and termination of events. The bolus head reached to pharynx and esophagus earlier and the duration of bolus passing through UES was significantly longer in 10 and 20 mL compared to 3 mL (P < .05). Consequently, the onset of UES opening was significantly earlier with increased volume (P < .05). LV and TVC closure occurred later in 20 mL compared to 3 mL (P < .05). These changes in motion of pharynx and larynx appeared to promote swallow safety by preventing aspiration, suggesting that anatomical structure movements adapt in response to bolus volume. Our findings also suggest that the pharyngeal swallow behaviours may be modified by afferents in the oral cavity. The three-dimensional visualization and quantitative measurements provided by 320-ADCT provide essential benchmarks for understanding swallowing, both normal and abnormal.

Ruxolitinib treatment for GvHD in patients with myelofibrosis

Jak1/2 inhibitor ruxolitinib is a promising agent for treating steroid-refractory GvHD after allogeneic hematopoietic stem cell transplantation (SCT) to produce quick and durable responses. However, optimal dose and tapering schedule of ruxolitinib remain to be determined. Discontinuation of ruxolitinib in myelofibrosis often induces 'withdrawal syndrome' characterized by acute relapse of the disease, but this issue is not well addressed in the treatment of GvHD. Four patients with GvHD (one acute and three chronic) after SCT for myelofibrosis were treated with ruxolitinib. Low-dose ruxolitinib at 5 mg/day was safe and effective, but one of two patients treated at 10 mg/day of ruxolitinib was complicated with severe cytopenia. Withdrawal syndrome developed in one patient, who died of recurrence of GvHD shortly after discontinuation of ruxolitinib. Slow tapering or maintenance with low-dose ruxolitinib inhibited GvHD flare. Our experience calls attention that initiation at low-dose of ruxolitinib may be safe and careful tapering schedule is required to avoid withdrawal syndrome in patients with GvHD after SCT for myelofibrosis.

Determination of HLA-A, -C, -B, -DRB1 allele and haplotype frequency in Japanese population based on family study

The present study investigates the human leucocyte antigen (HLA) allele and haplotype frequencies in Japanese population. We carried out the frequency analysis in 5824 families living across Japanese archipelago. The studied population has mainly been typed for the purpose of transplant, especially the hematopoietic stem cell transplantation (HSCT). We determined HLA class I (A, B, and C) and HLA class II (DRB1) using Luminex technology. The haplotypes were directly counted by segregation. A total of 44 HLA‐A, 29 HLA‐C, 75 HLA‐B, and 42 HLA‐DRB1 alleles were identified. In the HLA haplotypes of A‐C‐B‐DRB1 and C‐B, the pattern of linkage disequilibrium peculiar to Japanese population has been confirmed. Moreover, the haplotype frequencies based on family study was compared with the frequencies estimated by maximum likelihood estimation (MLE), and the equivalent results were obtained. The allele and haplotype frequencies obtained in this study could be useful for anthropology, transplantation therapy, and disease association studies.

Skeletal muscle-specific overproduction of constitutively activated c-Jun N-terminal kinase (JNK) induces insulin resistance in mice

AIMS/HYPOTHESIS

Although skeletal muscle insulin resistance has been associated with activation of c-Jun N-terminal kinase (JNK), whether increased JNK activity causes insulin resistance in this organ is not clear. In this study we examined the metabolic consequences of isolated JNK phosphorylation in muscle tissue.

METHODS

Plasmids containing genes encoding a wild-type JNK1 (WT-JNK) or a JNK1/JNKK2 fusion protein (rendering JNK constitutively active; CA-Jnk) were electroporated into one tibialis anterior (TA) muscle of C57Bl/6 mice, with the contralateral TA injected with an empty vector (CON) to serve as a within-animal control.

RESULTS

Overproduction of WT-JNK resulted in a modest (~25%) increase in phosphorylation (Thr(183)/Tyr(185)) of JNK, but no differences were observed in Ser(307) phosphorylation of insulin receptor substrate 1 (IRS-1) or total IRS-1 protein, nor in insulin-stimulated glucose clearance into the TA muscle when comparing WT-JNK with CON. By contrast, overexpression of CA-Jnk, which markedly increased the phosphorylation of CA-JNK, also increased serine phosphorylation of IRS-1, markedly decreased total IRS-1 protein, and decreased insulin-stimulated phosphorylation of the insulin receptor (Tyr(1361)) and phosphorylation of Akt at (Ser(473) and Thr(308)) compared with CON. Moreover, overexpression of CA-Jnk decreased insulin-stimulated glucose clearance into the TA muscle compared with CON and these effects were observed without changes in intramuscular lipid species.

CONCLUSIONS/INTERPRETATION

Constitutive activation of JNK in skeletal muscle impairs insulin signalling at the level of IRS-1 and Akt, a process which results in the disruption of normal glucose clearance into the muscle.

Evaluation of arterial stiffness after successful renal transplantation using brachial-ankle pulse wave velocity

BACKGROUND

Cardiovascular disease remains a main cause of mortality in renal transplant recipients. Determination of aortic stiffness with pulse wave velocity (PWV) is considered a strong predictor of cardiovascular risk. We investigated arterial stiffness with brachial-ankle pulse wave velocity (baPWV) after successful renal transplantation.

METHODS

We studied 197 patients (mean age = 53.2 ± 10.8 years) who underwent successful renal transplantation. baPWV was evaluated with a noninvasive automatic Omron Colin device. During follow-up (mean = 183.8 ± 108.9 months), we investigated parameters of sex, age, body mass index, duration before (dialysis) and after transplantation, and cardiovascular risk factors (hypertension and diabetes). In all subjects, fasting concentrations of serum creatinine, non-(HDL) high-density lipoprotein-cholesterol (total cholesterol minus HDL-cholesterol), low-density lipoprotein-cholesterol, and triglyceride were also compared with those at enrollment.

RESULTS

Mean baPWV levels were 1519 ± 329 cm/s in our renal transplant recipients. baPWV increased independent of age, duration of dialysis before transplantation, and cardiovascular risk factors. Serum creatinine and dilation did not show any significant correlations to baPWV.

CONCLUSION

In renal transplant recipients, baPWV may be more influenced by past clinical history before transplantation than by current condition. Noninvasive assessment of arterial stiffness with baPWV may be a useful and convenient indicator of cardiovascular disease after renal transplantation.