Mercury Sulfide Dimorphism in Thioarsenate Glasses.

Crystalline mercury sulfide exists in two drastically different polymorphic forms in different domains of the P,T-diagram: red chain-like insulator α-HgS, stable below 344 °C, and black tetrahedral narrow-band semiconductor ß-HgS, stable at higher temperatures. Using pulsed neutron and high-energy X-ray diffraction, we show that these two mercury bonding patterns are present simultaneously in mercury thioarsenate glasses HgS-As2S3. The population and interconnectivity of chain-like and tetrahedral dimorphous forms determine both the structural features and fundamental glass properties (thermal, electronic, etc.). DFT simulations of mercury species and RMC modeling of high-resolution diffraction data provide additional details on local Hg environment and connectivity implying the (HgS2/2)m oligomeric chains (1 ≤ m ≤ 6) are acting as a network former while the HgS4/4-related mixed agglomerated units behave as a modifier.

Response of sex ratio to timing of breeding in the small cyprinid Gnathopogon caerulescens.

The influence of hatching date on the sex ratio of wild Gnathopogon caerulescens was examined. Cohorts reared from eggs collected in the early and middle parts of the spawning season showed almost balanced sex ratios, with female bias in some cohorts. Cohorts born later in the season mostly displayed male bias, and the mean proportion of males later in the season was significantly higher than in early- and mid-season cohorts. These results indicate that the sex ratio of G. caerulescens changes with the time of breeding, increasing along with the ambient water temperature of the lake.

Amorphous Ge15Te85: density functional, high-energy x-ray and neutron diffraction study.

The structure and electronic properties of amorphous Ge(15)Te(85) have been studied by combining density functional (DF) simulations with high-energy x-ray and neutron diffraction measurements. Three models with 560 atoms have been constructed using reverse Monte Carlo methods constrained to (1) agree with the experimental structure factors S(Q), and have (2) energies close to the DF minimum and (3) a semiconducting band structure. The best structure is based on the melt-quenched DF structure and has a small number of Ge-Ge bonds. It shows interlocking networks of Te and GeTe with a significant fraction (22-24%) of voids (cavities). Ge occurs with both tetrahedral and 3 + 3 defective octahedral configurations, and the coordination of Te is slightly higher than indicated by the '8 - N rule' (N is the number of valence electrons). The GeTe network includes clusters of ABAB squares (A = Ge, B = Te), and the bonding is characterized by the chemical bond orders.

Few-electron molecular states and their transitions in a single InAs quantum dot molecule.

We study electronic configurations in a single pair of vertically coupled self-assembled InAs quantum dots, holding just a few electrons. By comparing the experimental data of nonlinear single-electron transport spectra in a magnetic field with many-body calculations, we identify the spin and orbital configurations to confirm the formation of molecular states by filling both the quantum mechanically coupled symmetric and antisymmetric states. Filling of the antisymmetric states is less favored with increasing magnetic field, and this leads to various magnetic field induced transitions in the molecular states.

Clinical and endocrinological features of adrenocorticotropic hormone- independent bilateral macronodular adrenocortical hyperplasia.

PURPOSE: We report clinical findings in 5 patients with adrenocorticotropic hormone independent bilateral macronodular adrenocortical hyperplasia. MATERIALS AND METHODS: In 4 males and 1 female 32 to 61 years old (median age 50) we evaluated clinical symptoms, endocrinological and radiological characteristics, treatment modality and postoperative clinical course. RESULTS: All cases presented with some features of Cushing's syndrome. Endocrinological examination revealed autonomous adrenal cortisol production with suppressed adrenocorticotropic hormone and a loss in the diurnal circadian rhythm of plasma cortisol. Abdominal computerized tomography showed bilateral enlargement of the adrenal glands with multiple nodules. 131Iodine labeled adosterol scintigraphy demonstrated remarkable bilateral uptake by the adrenal glands. The pituitary gland appeared normal on magnetic resonance imaging. Open unilateral complete adrenalectomy and contralateral partial adrenalectomy were performed in patient 1, open bilateral complete adrenalectomy was done in patients 2 and 3, and 2 and 1-stage laparoscopic bilateral complete adrenalectomy was performed in patients 4 and 5. Single removed adrenal glands weighed 32 to 108 gm. (median 60). The histological diagnosis was macronodular adrenocortical hyperplasia in all cases. Postoperative followup was 3 to 90 months. Clinical symptoms of Cushing's syndrome disappeared or improved after surgery in all cases. CONCLUSIONS: Although adrenocorticotropic hormone independent bilateral macronodular adrenocortical hyperplasia is a rare form of Cushing's syndrome, physicians are advised to consider it when diagnosing and treating cases of Cushing's syndrome with enlarged bilateral adrenal glands. Bilateral complete adrenalectomy is currently recommended as the treatment of choice.

Intravenous digital subtraction angiography and helical computed tomography in evaluation of living renal donors.

OBJECTIVES: The present study was carried out to evaluate the accuracy of helical computed tomography (CT) and intravenous digital subtraction angiography (IV-DSA) on anatomical assessment of renal vasculature for living renal donors. METHODS: Forty-two healthy potential renal donors were prospectively evaluated and 35 subsequently underwent donor nephrectomy after helical CT and IV-DSA evaluation. The vascular and non-vascular findings were compared between the findings on helical CT, IV-DSA and surgery. RESULTS: Ten prehilar branches and five accessory renal arteries were found at nephrectomy. Overall, operative findings agreed with the findings by IV-DSA in 89% and by helical CT in 83%. In delineating accessory arteries, IV-DSA had a sensitivity of 60% and specificity of 97%, whereas helical CT had a sensitivity of 40% and specificity of 100%. In delineating prehilar branches, IV-DSA had a sensitivity of 90% and specificity of 100%, whereas helical CT had a sensitivity of 70% and specificity of 100%. Accessory arteries and prehilar branches that were not detected by helical CT or IV-DSA, were less than 2 mm in diameter and did not require vascular reconstruction. Renal veins were delineated in 63% by IV-DSA, whereas they were clearly imaged by helical CT in all cases, including a case with a circumaortic renal vein. Non-vascular findings were obtained in 64% by helical CT, including two renal tumors. None of these findings were obtained by IV-DSA. CONCLUSION: Helical CT and IV-DSA provide comparably sufficient information on renal artery vasculature. However, helical CT provides significantly more information on venous and non-vascular findings as a single-imaging modality.

Pre-emptive renal transplantation in children.

BACKGROUND: Renal transplantation is a definitive therapeutic modality in end-stage renal disease (ESRD). Most ESRD patients in Japan experience dialysis prior to renal transplantation. The present study was undertaken to examine the usefulness of pre-emptive renal transplantation (PET). METHODS: Between 1987 and 1998, 255 renal transplantations were carried out by the authors. Among those consecutive cases, 10 were cases of PET. In nine pediatric cases, demographics, graft and patient survival, height growth and benefits from successful transplantation were studied and compared with age-matched dialyzed transplantation controls. RESULTS: All transplantation was living-related. There was a disparity of causes of ESRD between the two groups. In PET, acquired renal deterioration due to a congenital lower urinary tract disorder was the major cause. Graft and patient prognosis was favorable in both groups. Growth retardation in PET patients under 15 years of age was significantly less apparent at the time of transplantation and after 3 years compared to the control. The benefits from transplantation were different in the two groups. Most PET patients felt an improvement of their physical condition; however, all of the control patients felt that the major boon was the freedom from the restriction of the daily diet and time for dialysis. CONCLUSION: In pediatric renal transplantation, short-term preceding dialysis does not have a detrimental effect, but PET could benefit ESRD patients by maintaining their quality of life. Moreover, PET minimizes the production of renal dwarfism in prepubertal children. Thus, PET should be taken into consideration in the choice of renal replacement therapy.

Enterocolitis with pathogenic Escherichia coli infection in renal transplant recipients: case reports.

PURPOSE: We report three cases of enterocolitis associated with pathogenic Escherichia coli infection in renal transplant recipients. METHODS/RESULTS: Patients presented with abdominal pain and diarrhea at 1, 3 and 7 years after living-related renal transplantation. Pathogens of enterocolitis were identified by stool culture as verotoxin-2-producing O157:H7 E. coli, non-verotoxin-producing E. coli 06 and 0125. All patients were basically treated with fluid replacement with additional fosfomycin administration in the patient with O157:H7 E. coli infection. Immunosuppressive drugs were kept at maintenance doses throughout the treatment. CONCLUSION: All patients recovered uneventfully within 10 days after the onset of enterocolitis without severe complications.

Gastric antral vascular ectasia causing severe anemia.

Gastric antral vascular ectasia (GAVE) that caused continuous gastrointestinal bleeding is reported in a 76-year-old woman who had been treated with repeated blood transfusions because of severe anemia. Endoscopic examination was performed and diffuse speckled telangiectasia of the entire antrum was observed. Laboratory data showed SGOT > SGPT, decreased chE level and the increased levels of serum gastrin and ICG at 15 min. Anti-HCV antibody was positive. Image examination revealed splenomegaly. There was no family history of telangiectasia, and no telangiectasia was found in other organs. The diagnosis was established as GAVE with liver cirrhosis. Surgical resection of the distal stomach resulted in termination of the bleeding, and the cirrhotic changes of the surface of the liver were revealed at that time, providing further evidence of liver cirrhosis. Although the pathogenesis of GAVE is unknown, liver cirrhosis and hypergastrinemia are thought to be associated with the condition. Importantly, this condition is a cause of severe gastrointestinal bleeding in elderly patients.

Morphological changes in the hippocampus in amygdaloid kindled mouse.

To clarify the origin and maintenance of epileptogenesis, morphological changes in the hippocampus of amygdaloid-kindled mice were analyzed at different stages of kindling. The granule cell size in dentate gyrus and the pyramidal cell size in CA1 were clearly decreased depending on seizure stage. The cell size in CA2 was increased and density in dentate gyrus and CA2 was reduced, significantly. The morphological changes in hippocampus associated with kindling must be closely related to the acquisition and the maintenance of epileptogenesis. The results support the hypothesis that seizure-induced damage of neurons may lead to formation of new synaptic connections that produce abnormal hyperexitability and result in seizures.

Calyculin A increases voltage-dependent inward current in smooth muscle cells isolated from guinea pig taenia coli.

The effects of a potent phosphatase inhibitor, calyculin A (CL-A), on inward currents in guinea pig taenia coli smooth muscle cells were examined. CL-A increased the inward current, and this effect of CL-A was inhibited by a protein kinase C inhibitor, H-7, and by nifedipine. Phorbol 12,13-dibutyrate, an activator of protein kinase C, also increased the inward current and this effect was antagonized by H-7. These results suggest that in guinea pig taenia coli smooth muscle cells CL-A may facilitate the opening of the L-type Ca2+ channels through the protein kinase C-dependent phosphorylation system.