Ferromagnetism and electronic structures of nonstoichiometric Heusler-alloy Fe3-xMnxSi Epilayers grown on Ge(111)

For the study of ferromagnetic materials which are compatible with group-IV semiconductor spintronics, we demonstrate control of the ferromagnetic properties of Heusler-alloy Fe3-xMnxSi epitaxially grown on Ge(111) by tuning the Mn composition x. Interestingly, we obtain L2(1)-ordered structures even for nonstoichiometric atomic compositions. The Curie temperature of the epilayers with x approximately 0.6 exceeds 300 K. Theoretical calculations indicate that the electronic structures of the nonstoichiometric Fe3-xMnxSi alloys become half-metallic for 0.75 < or = x < or = 1.5. We discuss the possibility of room-temperature ferromagnetic Fe(3-x)Mn(x)Si/Ge epilayers with high spin polarization.

Vascular calcification and secondary hyperparathyroidism of severe chronic kidney disease and its relation to serum phosphate and calcium levels

BACKGROUND AND PURPOSE

Various complications consequent on disordered calcium and phosphate homeostasis occur frequently in chronic kidney disease (CKD) patients. Particularly, vascular calcification has high morbidity and mortality rates. There is a clear need for a better CKD model to examine various aspects of this disordered homeostasis.

EXPERIMENTAL APPROACH

Oral dosing with adenine induced CKD in rats in only 10 days. Serum calcium, phosphate and parathyroid hormone were measured and calcification in aorta was assessed histologically. The effects of varying phosphorus content of diet or treatment with phosphate binders or active vitamin D(3) on these parameters were examined.

KEY RESULTS

After adenine dosing, significant hyperphosphatemia, hypocalcemia and secondary hyperparathyroidism (2HPT) were observed during the experimental period of 15 weeks. Aortic calcification was detected in only some of the animals even at 15 weeks (approximately 40%). Treatment with vitamin D(3) for 18 days, even at a low dose (100 ng x kg(-1), 3-4 times week(-1), p.o), caused aortic calcification in all animals and increases in serum calcium levels up to the normal range. The vitamin D(3)-induced calcification was significantly inhibited by phosphate binders which lowered serum phosphate levels and the calcium x phosphate product, although serum calcium levels were elevated.

CONCLUSIONS

These data suggest that rats dosed orally with adenine provide a more useful model for analysing calcium/phosphate homeostasis in severe CKD. Controlling serum calcium/phosphate levels with phosphate binders may be better than vitamin D(3) treatment in hyperphosphatemia and 2HPT, to avoid vascular calcification.

Erythrocyte magnesium and prostaglandin dynamics in chronic sleep deprivation

BACKGROUND AND HYPOTHESIS

The mechanism of sudden cardiac death occurring in patients with chronic fatigue is controversial. This study was designed to define a hypothesis that coronary arterial spasm and thrombus formation can occur during chronic fatigue.

METHODS

For evaluating the feasibility of coronary arterial spasm, erythrocyte magnesium (Mg) was measured. Blood coagulability was evaluated by the change of prostaglandin concentration. Subjects included 16 healthy male volunteers (mean age 21.6 +/- 2.5 years). Test conditions were as follows: (A) control state: a day following a night of good sleep; (B) temporary sleep deprivation: a day preceded by < 3 h of sleep; (C) chronic sleep deprivation: a day preceded by a month during which sleep lasted < 60% of that in condition (A) above. The erythrocyte Mg concentration was measured by the atomic absorption method. The plasma concentration of thromboxane B2 and 6-keto-prostaglandin F1 alpha were measured in eight subjects by radioimmunoassay method.

RESULTS

(1) Mean erythrocyte Mg concentration was significantly less in chronic sleep deprivation (1.1 +/- 0.4 mg/dl) than in the control state (1.8 +/- 0.4 mg/dl, p < 0.01) or in temporary sleep deprivation (1.6 +/- 0.4, p < 0.01). (2) The level of thromboxane B2 was significantly higher during chronic sleep deprivation than under control conditions (104.4 +/- 78.0 vs. 20.4 +/- 9.0 pg/ml, p < 0.05). (3) There were no significant intergroup differences in 6-keto-prostaglandin F1 alpha level.

CONCLUSION

These findings could support the hypothesis that coronary arterial spasm and thrombus formation occur in chronic sleep deprivation.

Persistent diffuse pulmonary interstitial emphysema mimicking pulmonary emphysema

A 69-year-old male non-smoker with a history of atopic asthma presented with symptoms suggestive of chronic obstructive pulmonary disease and this appeared to be corroborated by lung function testing and a chest radiograph. However, a chest CT showed no evidence of pulmonary emphysema and instead demonstrated free air along the bronchovascular sheaths indicative of pulmonary interstistial emphysema, possibly caused by repeated prior exacerbations of asthma. His lung function tests and symptoms improved within months of being treated for his airways disease but the CT findings were unchanged after 2 years.

Heart and brain circulation and CO2 in healthy men

AIM

To compare blood flow response to arterial carbon dioxide tension change in the heart and brain of normal elderly men.

METHODS

Thirteen healthy elderly male volunteers were studied. Hypercapnea was induced by carbon dioxide inhalation and hypocapnea was induced by hyperventilation. Myocardial blood flow [mL min(-1) x (100 g of perfusable tissue)(-1)] and cerebral blood flow [mL min(-1) x (100 g of perfusable tissue)(-1)] were measured simultaneously at rest, under carbon dioxide gas inhalation and hyperventilation using the combination of two positron emission tomography scanners.

RESULTS

Arterial carbon dioxide tension increased significantly during carbon dioxide inhalation (43.1 +/- 2.7 mmHg, P < 0.05) and decreased significantly during hyperventilation (29.2 +/- 3.4 mmHg, P < 0.01) from baseline (40.2 +/- 2.4 mmHg). Myocardial blood flow increased significantly during hypercapnea (88.7 +/- 22.4, P < 0.01) from baseline (78.2 +/- 12.6), as did the cerebral blood flow (baseline: 39.8 +/- 5.3 vs. hypercapnea: 48.4 +/- 10.4, P < 0.05). During hypocapnea cerebral blood flow decreased significantly (27.0 +/- 6.3, P < 0.01) from baseline as did the myocardial blood flow (55.1 +/- 14.6, P < 0.01). However, normalized myocardial blood flow by cardiac workload [100 mL mmHg(-1) x (heart beat)(-1) x (gram of perfusable tissue)(-1)] was not changed from baseline (93.4 +/- 16.6) during hypercapnea (90.5 +/- 14.3) but decreased significantly from baseline during hypocapnea (64.5 +/- 18.3, P < 0.01).

CONCLUSION

In normal elderly men, hypocapnea produces similar vasoconstriction both in the heart and brain. Mild hypercapnea increased cerebral blood flow but did not have an additional effect to dilate coronary arteries beyond the expected range in response to an increase in cardiac workload.

Effect of direct retainer and major connector designs on RPD and abutment tooth movement dynamics

Designs of removable partial dentures are suggested to affect the mobility of abutment teeth and removable partial denture (RPD) during oral functions. This study aimed to examine the effect of direct retainer and major connector designs on RPD dynamics under simulated loading. Six different Kennedy class II maxillary RPDs were fabricated on a maxillary model. These dentures involved 3 different direct retainers (wrought-wire clasp, RPA clasp, and conical crown telescopic retainer) and 2 different major connectors (Co-Cr major connector and heat-cured acrylic resin with a metal strengthener). Using an experimental model with simulated periodontal ligaments and mucosa that were fabricated using silicone impression material, three-dimensional displacements of the RPDs were measured under a simulated 30-N loading with a displacement transducer type M-3. Significant effects of "direct retainer design" on bucco-palatal displacements and "major connector" on mesio-distal displacements were revealed by 2 x 3 two-way analysis of variance of abutment teeth movements (P < 0.001 and P = 0.002, respectively). Additionally, analysis of variance of RPD displacements revealed significant effects of "direct retainer design" on corono-apical displacements and "major connector" on mesio-distal displacements (P = 0.001 and P = 0.028, respectively). Rigid direct retainers and rigid major connectors decrease the movements of both abutment tooth and RPD.

Presence of perivenular elastic fibers in nonalcoholic steatohepatitis Fibrosis Stage III

Elastic fibers appear in extensive old fibrotic foci in general. We examined an association between hepatic fibrosis stage and the presence of perivenular elastic fibers in nonalcoholic steatohepatitis (NASH). A total of 48 liver needle biopsy specimens were used, taken from 48 cases with NASH. Fibrosis Stage (Brunt E, et al. Am. J. Gastroenterol. 1999) of the cases was as follows; six Fibrosis Stage I, twenty-two Fibrosis Stage II, and twenty Fibrosis Stage III. We examined Orcein stain sections in all of the liver needle biopsy specimens. In all twenty Fibrosis Stage III cases, perivenular elastic fiber bundles were observed. In contrast, perivenular elastic fibers were detected only in one of the six Fibrosis Stage I and two of the twenty-two Fibrosis Stage II cases. In liver needle biopsy specimens of NASH, detection of perivenular elastic fibers is useful in deciding Fibrosis Stage III.

T1 signal intensity and height of the anterior pituitary in neonates: correlation with postnatal time

BACKGROUND AND PURPOSE

The anterior pituitary of a term neonate is usually hyperintense on T1-weighted MR images, which may represent histologic changes of the gland due to the effect of high estrogen levels during the fetal period; however, MR findings of a preterm neonate have not been fully evaluated. The purpose of this study was to investigate whether intensity and size of the neonatal anterior pituitary on MR images obtained near term of corrected age correlates with the gestational age at birth or postnatal time.

MATERIALS AND METHODS

Data of 88 consecutive neonates (gestational age, 24-41 weeks; mean, 31.5 weeks) were analyzed. All of the neonates underwent MR imaging at a corrected age of 0 months +/- 4 weeks. Relative signal intensity of the anterior pituitary compared with that of the pons on T1-weighted sagittal images was calculated. Height of the pituitary was also measured. Stepwise regression analysis was performed to evaluate the effects of gestational age at birth and postnatal time on the relative signal intensity and on the pituitary height.

RESULTS

The relative signal intensity significantly negatively correlated with postnatal time (P = .001) but not with gestational age at birth (P = .42). Pituitary height significantly negatively correlated with postnatal time (P = .049) but not with gestational age at birth (P = .071).

CONCLUSION

A significant negative correlation exists between postnatal time and signal intensity on T1-weighted MR images of the anterior pituitary obtained near term. A nonhyperintense anterior pituitary is a normal MR finding of preterm neonates when imaged near term.

[Aortic root abscess after percutaneous coronary intervention]

A 68-year-old man, who had undergone percutaneous coronary intervention for right coronary disease 2 weeks earlier, was admitted to our hospital for investigation of a fever. Blood culture and echocardiography revealed isolated aortic valve infective endocarditis. He was treated with antibiotics for more than 1 week, but echocardiography showed an aortic root abscess with severe aortic regurgitation. Thus, we performed aortic root replacement using an artificial Freestyle stentless bioprosthesis valve. The patient had an uneventful postoperative course and antibiotic treatment was continued for a further 8 weeks.

Report of takotsubo cardiomyopathy occurring during cardiopulmonary bypass

On weaning from cardiopulmonary bypass, a 59-year-old Japanese woman with mitral valve plasty suddenly showed a greatly increased heart rate, and an electrocardiogram revealed elevated ST-segments. There was also abnormal wall motion in the inferior region and apical ballooning of the left ventricle. We diagnosed the condition as takotsubo cardiomyopathy (acute left ventricle apical ballooning syndrome), possibly caused by catecholamine release and regional stress-induced ischemia. We believe this to be the first case report of takotsubo cardiomyopathy observed during heart surgery. We hypothesize that the condition was mediated by regional myocardial stunning and that it could be prevented by administration of angiotensin converting enzyme inhibitors before surgery and by the use of superior biocompatible cardiopulmonary bypass components. Once takotsubo cardiomyopathy occurs, we recommend mechanical circulatory assistance during weaning from the bypass.

Endoscopic submucosal dissection for rectal tumors

BACKGROUND AND STUDY AIM

Endoscopic submucosal dissection (ESD) has recently been developed for one-piece resection of gastric tumors. In order to improve patients' quality of life, it may be desirable to use the same technique for rectal tumors.

METHODS

35 consecutive patients with rectal tumors were enrolled. ESD was carried out using the same technique as for the stomach. The efficacy, technical feasibility, operation time, complications, and follow-up results were assessed.

RESULTS

The mean size of the epithelial tumors was 26.2 +/- 14.0 mm, and the rates of one-piece resection and one-piece resection with tumor-free margins were 73.3% (22 of 30) and 70.0% (21 of 30), respectively. The median operation time was 70 min (range 8-360 min). All five carcinoid tumors were completely resected. No patient needed blood transfusion or had the complication of problematic bleeding. Perforation during ESD occurred in one patient (2.9%), who was managed with conservative medical treatment after endoscopic closure of the perforation. Excluding seven patients, who either underwent additional surgery or whose follow-up period was less than 1 year, all 23 patients with epithelial tumors were free of recurrence during a mean follow-up period of 25.7 months (range 12-53 months).

CONCLUSIONS

ESD was thus found to be feasible for the treatment of rectal tumors, with promising results although the follow-up periods were short. ESD may therefore be indicated for rectal tumors which are not resectable en bloc by conventional procedures, in order to improve the patients' quality of life.