The Importance of Biologically Active Vitamin D for Mineralization by Osteocytes After Parathyroidectomy for Renal Hyperparathyroidism.

Hypomineralized matrix is a factor determining bone mineral density. Increased perilacunar hypomineralized bone area is caused by reduced mineralization by osteocytes. The importance of vitamin D in the mineralization by osteocytes was investigated in hemodialysis patients who underwent total parathyroidectomy (PTX) with immediate autotransplantation of diffuse hyperplastic parathyroid tissue. No previous reports on this subject exist. The study was conducted in 19 patients with renal hyperparathyroidism treated with PTX. In 15 patients, the serum calcium levels were maintained by subsequent administration of alfacalcidol (2.0 µg/day), i.v. calcium gluconate, and oral calcium carbonate for 4 weeks after PTX (group I). This was followed in a subset of 4 patients in group I by a reduced dose of 0.5 µg/day until 1 year following PTX; this was defined as group II. In the remaining 4 patients, who were not in group I, the serum calcium (Ca) levels were maintained without subsequent administration of alfacalcidol (group III). Transiliac bone biopsy specimens were obtained in all groups before and 3 or 4 weeks after PTX to evaluate the change of the hypomineralized bone area. In addition, patients from group II underwent a third bone biopsy 1 year following PTX. A significant decrease of perilacunar hypomineralized bone area was observed 3 or 4 weeks after PTX in all group I and II patients. The area was increased again in the group II patients 1 year following PTX. In group III patients, an increase of the hypomineralized bone area was observed 4 weeks after PTX. The maintenance of a proper dose of vitamin D is necessary for mineralization by osteocytes, which is important to increase bone mineral density after PTX for renal hyperparathyroidism. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

Active vitamin D analogs, maxacalcitol and alfacalcidol, as maintenance therapy for mild secondary hyperparathyroidism in hemodialysis patients - a randomized study.

BACKGROUND: The present randomized study was designed to compare the efficacy between two active vitamin D analogs, alfacalcidol (ACD) and maxacalcitol (OCT), for the management of mild secondary hyperparathyroidism (SHPT) in dialysis patients. METHODS: SHPT in all 32 patients analyzed in the study was initially treated with OCT. Once patients' intact PTH levels decreased to the target range of 150 - 180 pg/mL, they were randomized either to switch to ACD at 0.5 µg/day (n = 14), or to remain on an effectively unchanged dose of OCT (n = 13). Phosphate, calcium, and intact PTH levels were measured every 2 weeks for 12 weeks and vitamin D doses were changed according to target ranges of phosphate (3.5 - 6.0 mg/dL), calcium (albuminadjusted calcium: 8.4 - 10.0 mg/dL), and intact parathyroid hormone (60 - 180 pg/mL). Achievement rates of the target ranges of the parameters were estimated. RESULTS: Baseline calcium levels in the OCT group were significantly higher than in the ACD group. Changes in achievement rates of target ranges of intact PTH and calcium during the study did not differ significantly between the vitamin D drugs. Changes in calcium levels in the OCT and ACD groups were similar during the study. Achievement rates of the target range of phosphate in both groups were also similar until 8 weeks, although the rate in the OCT group declined at 10 weeks. CONCLUSIONS: The efficacy and safety of OCT for the treatment of mild SHPT are similar to those of ACD in hemodialysis patients.

Molecular dynamics simulation study on the structural stabilities of polyglutamine peptides.

It is known that Huntington's disease patients commonly have glutamine (Q) repeat sequences longer than a critical length in the coding area of Huntingtin protein in their genes. As the polyglutamine (polyQ) region becomes longer than the critical length, the disease occurs and Huntingtin protein aggregates, both in vitro and in vivo, as suggested by experimental and clinical data. The determination of polyglutamine structure is thus very important for elucidation of the aggregation and disease mechanisms. Here, we perform molecular dynamics calculations on the stability of the structure based on the beta-helix structure suggested by Perutz et al. (2002) [Perutz, M.F., Finch, J.T., Berriman, J., Lesk, A., 2002. Amyloid fibers are water-filled nanotubes. Proc. Natl. Acad. Sci. USA 99, 5591]. We ensure that perfect hydrogen bonds are present between main chains of the beta-helix based on the previous studies, and perform simulations of stretches with 20, 25, 30, 37 and 40 glutamine residues (20Q, 25Q, 30Q, 37Q and 40Q) for the Perutz models with 18.5 and 20 residues per turn (one coil). Our results indicate that the structure becomes more stable with the increase of repeated number of Q, and there is a critical Q number of around 30, above which the structure of the Perutz model is kept stable. In contrast to previous studies, we started molecular dynamics simulations from conformations in which the hydrogen bonds are firmly formed between stacked main chains. This has rendered the initial beta-helix structures of polyQ much more stable for longer time, as compared to those proposed previously. Model calculations for the initial structures of polyQ dimer and tetramer have also been carried out to study a possible mechanism for aggregation.

[Case of epicardial left ventricular pacing lead implantation under general anesthesia in a patient with severe cardiac dysfunction].

An 82-year-old man with severe cardiac dysfunction due to ischemic cardiac myopathy was diagnosed as indication for biventricular pacing. His left ventricular ejection fraction was 22%. Because of difficulty in coronary sinus lead fixation, epicardial lead implantation through a thoracotomy under general anesthesia was scheduled. Intraaortic balloon pumping (IABP) was started prior to the operation. Anesthesia was induced by midazolam and fentanyl, and maintained with fentanyl and low dose propofol infusion. Milrinone was infused throughout the operation. Except for just after the anesthesia induction, systolic blood pressure was kept well around 100 mmHg. The operation was completed without any ploblems. NYHA classification improved markedly (class IV to class II) by biventricular pacing. Using IABP, we could maintain blood pressure and stabilize hemodynamics during left ventricular lead implantation in a patient with severe heart failure.

Temperature effect on the selective hydration of sodium ion in nitrobenzene.

The effect of the temperature on the co-extraction of water molecules with Na+ from water to nitrobenzene (NB) in the presence of dipicrylaminate ion has been studied. The number (n) of water molecules co-extracted with a Na+ ion, as measured by the Karl Fischer method, increased from 3.1 to 5.2 with increasing temperature (6-65 degrees C). This observation is in apparent contradiction to the expectation from simple thermodynamics because hydration is generally an entropically unfavorable process. Additional 1H NMR experiments for the selective hydration of Na+ in deuterated NB have confirmed that the association constants of water with Na+ indeed decrease with increasing temperature. On the other hand, however, it has been shown that water solubility into NB substantially increases with temperature. We conclude that the latter effect overwhelms the former unfavorable entropy effect, which results in a net increase of the n-value, as observed.

[An analysis on blood transfusion for hepatic resection].

BACKGROUND: Hepatic resection is prone to significant blood loss. Adverse effects of blood loss and transfusion mandate improvements in surgical techniques to reduce blood loss and transfusion. METHODS: We retrospectively analyzed the present status of intraoperative blood transfusion practice of 42 hepatic resections in National Kure Medical Center for the year of 2000. RESULTS: Median values for blood loss were 1355, 1708, 1415, and 2298 ml for nonanatomic, subsegmental, segmental and extended right resections, respectively. Crossmatched to transfused blood (C/T) ratios were 1.76, 1.19, 2.31, and 0.90 for nonanatomic, subsegmental, segmental and extended right resections, respectively. CONCLUSION: In general, C/T ratio of 1.5 to 2.5 has been recommended but own C/T ratios are 1.19 and 0.9 for subsegmental and extended right hepatic resection, which are lower than recommended values. It was estimated that inappropriate prediction of blood loss by several surgeons and unused maximum surgical blood order schedule (MSBOS) or type and screen (T&S) decreased these values of C/T ratio in the present analysis. We therefore conclude that MSBOS and T&S could be improved by avoiding such in appropriate prediction.