Structures and stabilities of higher coordinate onium-boronium dications (X(+)BH(3)+ and X(+)BH(5)+; X = NH(3), PH(3), H(2)O,and H(2)S)

Structures of higher coordinate onium-boronium dications (X(+)BH(3)+ 1-4a and X(+)BH(5)+ 1-4d; X = NH(3), PH(3), H(2)O, and H(2)S) were calculated by using the ab initio method at the MP2/6-311+G** level. All of the dications 1-4a contain a four-coordinate boron atom with a three-center two-electron bond involving boron and two hydrogens. On the other hand, all the dications 1-4d contain a six-coordinate boron atom with two three-center two-electron bonds. The thermodynamics of the complexations of 1-4a and H(2) to form 1-4d were computed. Deprotonations of 1-4d were found to be substantially endothermic.     

Tacrolimus (FK 506), a Treatment for Primary Sclerosing Cholangitis: Results of an Open-Label Preliminary Trial

Primary sclerosing cholangitis (PSC) is a chronic inflammatory disease of the liver that is characterized by progressive cholestasis and the development of secondary biliary cirrhosis. There is no widely recognized therapy for this disease, although anti-inflammatory agents (steroids), immunosuppressive agents (methotrexate), anti-fihrotics (colchicine), and choleretic agents (ursodeoxycholic acid) have been used in various small series. In the present study, Tacrolimus (FK 506), a new and powerful immunosuppressive macrolide antibiotic, has been used to treat 10 patients with PSC. Each subject had a liver biopsy, ERCP with visualization of the intra-and extrahepatic biliary tree, and a panel of hcmatological, serological, and biochemical laboratory tests before the initiation of the FK 506 therapy. The FK 506 was administered orally at 12-h intervals and was monitored by serial plasma FK 506 trough levels. After 360 days of treatment, the median serum bilirubin level was reduced by 75%, and the serum alkaline phosphatase was reduced by 70%. Moreover, the serum ALT and AST levels were reduced by 80 and 86%, respectively. No change in the serum level of BUN and creatinine levels occurred as a consequence of the FK 506 treatment. These data demonstrate that: 1) FK 506 can be used to treat PSC; 2) the response to FK 506 by patients with PSC is rapid; and, 3) no adverse effect on the serum BUN and creatinine levels was observed. It is anticipated that FK 506 will become an important agent for the treatment of patients with PSC because of its powerful immunosuppressive activity.     

Comparison of FEV(3), FEV(6), FEV(1)/FEV(3) and FEV(1)/FEV(6) with usual spirometric indices

Background and objective: Pulmonary function tests play an important role in the management of pulmonary diseases. One of the tests that are widely used is spirometry. Performing an acceptable spirometry manoeuvre according to the standards set by the American Thoracic Society/European Respiratory Society is difficult. The aim of this study was to compare forced expiratory volume in 3 s (FEV₃) and forced expiratory volume in 6 s (FEV₆) with forced vital capacity (FVC), and forced expiratory volume in 1 s FEV₁/FEV₃ and FEV₁/FEV₆ with FEV₁/FVC, in order to substitute the usual spirometric manoeuvres with manoeuvres that are easier to perform. Methods: In a cross‐sectional study, spirometry was performed for 588 subjects who were referred for occupational health evaluations. The accuracy of FEV₃, FEV₆, FEV₁/FEV₃ and FEV₁/FEV₆ was compared with that of FVC and FEV₁/FVC. Chi‐square tests and kappa tests were used to analyse the data. Results: Individuals with normal (n = 297) and abnormal spirometry (n = 291) were evaluated. The sensitivity, specificity, positive predictive value and negative predictive value of FEV₁/FEV₆, as compared with that of FEV₁/FVC for detecting obstruction, were 93.56, 99.32, 98.95 and 96.09, respectively. The sensitivity, specificity, positive predictive value and negative predictive value of FEV₆, as compared with that of FVC for detecting restriction, were 96.68, 98.65, 96.68 and 98.65, respectively. Conclusions: FEV₆ and FEV₁/FEV₆ can be used as surrogates for FVC and FEV₁/FVC, respectively, and these parameters showed acceptable sensitivity, specificity, positive predictive value and negative predictive value for occupational health evaluations.     

Icosahedral quasicrystals as twins of cubic crystals containing large icosahedral clusters of atoms: The 1012-atom primitive cubic structure of Al(6)CuLi(3), the C-phase Al(37)Cu(3)Li(21)Mg(3), and GaMg(2)Zn(3)

Single-grain precession x-ray diffraction photographs of Al₆CuLi₃ have been successfully indexed on the basis of icosahedral twinning of cubic crystals with a 1012-atom primitive cubic unit with edge 25.70 Å, giving support to the proposal that the so-called icosahedral quasicrystals are twins of crystals containing eight large icosahedral clusters in the β-W arrangement. In this compound two of the clusters consist of 104 atoms and six consist of 136 atoms, with 24 atoms shared. The same structure is assigned to the C-phase, Al₃₇Cu₃Li₂₁Mg₃, and to GaMg₂Zn₃. A theory of icosahedral quasicrystals and amorphous metals is described.     

Prolactin (PRL), thyrotropin (TSH), free thyroid hormones (fT4), (fT3) and testosterone (TTE) level in men with chronic heart failure

Chronic heart failure (CHF) is a global disease in which beside renin-angiotensin-aldosterone (RAA) system most endocrinal glands are affected. The occurrence of these disorders depends on the degree of heart failure. The influence on prognosis and therapeutic strategy is not known. The aim of this study was to evaluate the frequency of secretion disturbances of chosen hormones: prolactin (PRL), testosterone (TTE), thyroid hormones fT3, fT4 and TSH in a group of male in NYHA functional class II-IV and left ventricular ejection fraction less than 35% dependently on clinical degree of CHF and left ventricular defect. 27 male aged 35-83 years (mean 55,4) with different etiology of heart failure were enrolled in to the study. 3 groups (A, B, C) were selected dependently on NYHA class-group A - NYHA II (9), B - NYHA III (8), C - NYHA IV (10) and D group of healthy volunteers. 3 other groups were selected accordingly to left ventricular ejection fraction - I - 30-35% (14), II - 20-29% (8), III - <20% (5), IV - normal ventricular ejection fraction (10). The immunofluorescent tests were used for measuring chosen hormones concentration in blood serum. In 14 from 27 (52%) hormonal disturbances were found. No changes were noted in group A. All noted disturbances were observed in group B and C (NYHA class III/IV) more frequent in group C (90%) vs B (75%). This relation was not observed in connection with left ventricular ejection fraction. Elevated serum PRL (8) and decreased TTE concentration (5) were the most frequent hormone changes in whole study group. Results of this study confirm that CHE is often accompanied by disturbances in endocrinal glands secretion. The frequency of these disturbances rises with the degree of clinical advance of CHF.     

Changing concentrations of CO, CH(4), C(5)H(8), CH(3)Br, CH(3)I, and dimethyl sulfide during the Southern Ocean Iron Enrichment Experiments

Oceanic iron (Fe) fertilization experiments have advanced the understanding of how Fe regulates biological productivity and air-sea carbon dioxide (CO(2)) exchange. However, little is known about the production and consumption of halocarbons and other gases as a result of Fe addition. Besides metabolizing inorganic carbon, marine microorganisms produce and consume many other trace gases. Several of these gases, which individually impact global climate, stratospheric ozone concentration, or local photochemistry, have not been previously quantified during an Fe-enrichment experiment. We describe results for selected dissolved trace gases including methane (CH(4)), isoprene (C(5)H(8)), methyl bromide (CH(3)Br), dimethyl sulfide, and oxygen (O(2)), which increased subsequent to Fe fertilization, and the associated decreases in concentrations of carbon monoxide (CO), methyl iodide (CH(3)I), and CO(2) observed during the Southern Ocean Iron Enrichment Experiments.     

3种天山蕨类植物体外抑菌活性研究

目的筛选新疆天山蕨类植物抑菌活性种类和药用部位.方法用滤纸片法,用3种蕨类植物营养叶、孢子叶和茎的乙醇提取液,对7种供试菌进行了抑菌活性测试.结果 3种蕨类植物营养叶、孢子叶和茎对6种实验菌都有良好的抑菌活性;3种蕨类植物对大肠杆菌、金黄色葡萄球菌和八叠球菌有较强的抑菌作用,对短芽孢杆菌、枯草芽孢杆菌和铜绿假单孢菌的作用较弱,而对白色念珠菌无任何抑菌作用.结论不同浓度的样品具有不同程度的抑菌作用.     

Comparison of inhibitory effects of 3,5,3'-triiodothyronine (T3), thyroxine (T4), 3,3,',5'-triiodothyronine (rT3), and 3,3'-diiodothyronine (T2) on thyrotropin-releasing hormone-induced release of thyrotropin in the rat in vitro.

In order to compare, in vitro, the TSH suppressive effects of iodothyronines, rat pituitary quarters were first preincubated with T4, T3, rT3, or 3,3'-diiodothyronine (T2) in Gey and Gey buffer containing 1% bovine serum albumin for 2 h at 37 C and then incubated at 37 C for 1 h with the iodothyronine under study and TRH. TSH released into the medium during incubation was compared to that released by control pituitary fragments, which were not exposed to iodothyronines. All four iodothyronines (T3, T4, rT3, and T2) were able to significantly inhibit the TRH-induced release of TSH from pituitary fragments in a dose range of 0.015-2.2 microgram/ml. However, much larger doses of sodium iodide (1.25 mg/ml) and diiodotyrosine (10 and 30 microgram/ml) had no significant effect on the release of TSH. Among T3, rT3, and T4, T3 was the most potent and rT3 was the least potent. The relative potency of T3:T4:rT3 appeared to be approximately 100:12:1 when estimated from the lowest doses that caused significant inhibition of TRH-induced release of TSH, and approximately 100:6:0.5 when estimated from the doses that caused 50% inhibition of TSH release; the TSH inhibiting potency of T2 was similar to that of rT3. The activity of T4 could not be explained entirely on the basis of contamination of T4 with T3 or by in vitro conversion of T4 to T3. Similarly, the available data suggested that rT3 and T2 possess some, albeit modest, intrinsic TSH-Suppressive activity. TSH-inhibiting activities of T3, T4, and rT3 were also studied using pituitary fragments from starved and iodine-deficient rats. There was no evidence of a change in the sensitivity of the thyrotroph to either T3 or T4 in starvation. Similarly, comparison of the responses to several doses of rT3 did not indicate any significant abnormality in the sensitivity of the thyrotroph to rT3 in starvation or iodine deficiency. However, comparison of the TSH-suppressive effects of T4 in the iodine-deficient and normal rat indicated a significant increase in the sensitivity of the thyrotroph to T4 in iodine deficiency. A similar trend was also evident in the effect of T3 in iodine deficiency, but it fell short of statistical significance.     

“五日戒烟法”戒烟效果初探

“五日戒烟法”起始于１９５９年美国，并逐渐向世界各国推广。我们以北京经贸大学１４名行政干部为对象，为他们组织参加为期五天的讲座，并定期随访以评价其戒烟效果。结果显示：五天内全戒者占２５％，全组平均吸烟量由１７．７支降为５．０支，下降了１２．７支。经过三个月的随访，平均每天吸烟量仍保持在６．０支。说明该法不失为一种有效的戒烟法。     

Some Results on Parameter Identification of Nonlinear Systems

A priori global identifiability deals with the (theoretical) uniqueness of solutions of model parameters from noise free input–output data. This issue is particularly critical when dealing with physiological systems where a different numerical estimate can distinguish a pathological state from a normal state. Recently, differential algebra tools have been applied to study identifiability of dynamic systems described by polynomial or rational equations. These methods are based on elimination theory for algebraic differential systems, the main tool being the computation of the so-called characteristic set of a differential ideal associated to the polynomials defining the dynamic system. This characteristic set can be found by symbolic computation and provides the so-called exhaustive summary of the model.The reparametrization of the input–output relation of the system by the exhaustive summary plays a major role not only in a priori identifiability but also in parameter estimation of nonlinear models. It is in fact a linear reparametrization and can be used to derive explicit one-shot least-squares estimates of the parameters. This allows to avoid the usual bottleneck of nonlinear parameter optimization which has to be performed by iterative optimization routines which are often unreliable, e.g. they give no guarantee of converging to a true minimum, and hence require time-consuming random search in the parameter space. Our algorithm has been tested in one- and two-dimensional Michaelis–Menten model where the choice of initial values of the parameters is critical since nonlinear least-squares minimization problem shows many local minima. Our method structurally has only one minimum and does not require initial values for the unknown parameters. However, when noise in the data is present, the optimization problem is highly ill-conditioned and the solution of the problem in the general case is still under study.     

A possible effector role for the pleckstrin homology (PH) domain of dynamin

The large GTPase dynamin plays a key role in clathrin-mediated endocytosis in animal cells, although its mechanism of action remains unclear. Dynamins 1, 2, and 3 contain a pleckstrin homology (PH) domain that binds phosphoinositides with a very low affinity (K_D > 1 mM), and this interaction appears to be crucial for function. These observations prompted the suggestion that an array of PH domains drives multivalent binding of dynamin oligomers to phosphoinositide-containing membranes. Although in vitro experiments reported here are consistent with this hypothesis, we find that PH domain mutations that abolish dynamin function do not alter localization of the protein in transfected cells, indicating that the PH domain does not play a simple targeting role. An alternative possibility is suggested by the geometry of dynamin helices resolved by electron microscopy. Even with one phosphatidylinositol-4,5-bisphosphate [PtdIns(4,5)P₂] molecule bound per PH domain, these dynamin assemblies will elevate the concentration of PtdIns(4,5)P₂ at coated pit necks, and effectively cluster (or sequester) this phosphoinositide. In vitro fluorescence quenching studies using labeled phosphoinositides are consistent with dynamin-induced PtdIns(4,5)P₂ clustering. We therefore propose that the ability of dynamin to alter the local distribution of PtdIns(4,5)P₂ could be crucial for the role of this GTPase in promoting membrane scission during clathrin-mediated endocytosis. PtdIns(4,5)P₂ clustering could promote vesicle scission through direct effects on membrane properties, or might play a role in dynamin''s ability to regulate actin polymerization.