New Spirostanol Sulfonate from the Rhizomes of Helleborus thibetanus(Ranunculaceae)

A new spirostanol sulfonate, spirost-5,25（27）-dien-1β,3β-diol 1-sulfonate（1）, was isolated from the rhizomes of Helleborus thibetanus（Ranunculaceae）, and the structure was identified on the basis of a detailed spectroscopic analyses, including 2D NMR spectrometry, IR and HRESI-MS.

Influence of Basicity on the Formation of Cluster Ions/Adduct Ions for Organic Ammonium Halides by Positive Secondary Ion Mass Spectrometry

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SQUAMOSTATIN-B, A NEW POLYKETIDE FROM ANNONA SQUAMOSA (ANNONACEAE)

Squamostatin-B (1), a new polyketide or acetogenin, has been isolated from Annona squamosa L. (Annonaceae). Its structure and relative atereochemistry were elucidated on the basis of the spectral analyses of 1 and its derivatives, the acetate (2) and mesitoate (3).

Diagnosis and treatment of melamine-associated urinary calculus complicated with acute renal failure in infants and young children

Background Infants in some areas of China developed urinary lithiasis after being fed with powdered milk that was tainted with melamine in 2008 and very small proportion of the infants developed acute renal failure caused by urinary tract calculus obstruction. The aim of this article was to summarize clinical characteristics, diagnosis and treatment of infants with urinary calculus and acute renal failure developed after being fed with melamine tainted formula milk. Methods Data of infant patients with urinary calculus and acute renal failure due to melamine tainted formula milk admitted to the Beijing Children＇s Hospital Affiliated to the Capital Medical University and the Xuzhou Children＇s Hospital in 2008 were used to analyze the epidemiological characteristics, clinical manifestations, imaging features as well as effects of 4 types of therapies. Results All the 34 infants with urinary calculus were complicated with acute renal failure, their blood urea nitrogen （BUN） was （24.1±8.2） mmol/L and creatinine （Cr） was （384.2±201.2） umol/L. The chemical analysis on the urinary calculus sampled from 15 of the infants showed that the calculus contained melamine and acidum uricum. The time needed for the four types of therapies for returning Cr to normal was （3.5±1.9） days for cystoscopy group, （2.7±1.1） days for lithotomy group, （3.8±2.3） days for dialysis group, and （2.7±1.6） days for medical treatment group, which had no statistically significant difference （P=-0.508）. Renal failure of all the 34 infants was relieved within 1 to 7 days, averaging （3.00±1.78） days. Conclusions Melamine tainted formula milk may cause urinary calculus and obstructive acute renal failure. It is suggested that firstly the patients with urinary calculus complicated with acute renal failure should be treated with dialysis or medication to correct electrolyte disturbance, in particular hyperkalemia, and then relieve the obstruction with available medical and surgical methods as soon as possible. It was observed that the short-term prognosis was satisfactory.

Three-dimensional solution structure of ω-conotoxin SO_(3) determined by ^(1)H NMR

Cone snails (Conus) elaborate a series of conotoxin (CTX) peptides in their venoms to paralyze their prey. Among these toxins, w-CTX抯 specifically target to presynaptic voltage-gated calcium channel subsets, causing inhibition of neurotransmitter release. w-CTX SO3 was isolated from the venom of Conus striatus, which is the only available fish-hunting snail near the coast of the South China Sea. The three-dimensional solution structure of w-CTX SO3, a peptide which is the only w-conotoxin reported to show high homology with another w-CTX (MVIIA from C. Magus), has been determined by 1H NMR techniques. The molecular structure of w-CTX SO3 is stabilized by three disulfide bridges and a short triple-stranded antiparallel b-sheet with four turns. A comprehensive comparison suggested that the backbone conformation of w-CTXs was quite conserved, while the length of b-sheet and the type of some turns might have minor differences.

Novel and Convenient Approach to Synthesis of AZT/d4T H-phosphonates

A convenient, efficient and general method has been developed for synthesis of H-phosphonate mono and diesters of AZT and d4T through one-pot reaction of phosphonic acid with AZT or d4T and different alcohols using pivaloyl chloride as condensing agent under mild conditions.

Effect of Reactive Oxygen Species on Structure of CuZn-SOD by 1HNMR

1 Introduction Cupro-zlnc superoxide dlsmutase（CuZn-SOD）1s a dimeric enzyme,inade of two identical SUbunits,each contai ning a Cu（Ⅱ）ion and a Zn（Ⅱ）ion.His44,His46,His61,His118 and one molecule of H2O are involved in the binding of Cu（Ⅱ）,while His61,His69,His78 and ASP81 coordinate to Zn（Ⅱ）. A great deal of evidence indicates that CuZnSOD is resistant to many chemical reagents or phySical treatment,whereas itis quite susceptible to reactiVe OXygen species SUCh as H2O2 or ascorbate-Fe（Ⅲ）system,demonstrating inactivation and physicochernical properties alterations.It is of biological significance to study the inactiVation mechanism of CuZn-SOD by reactive Oxygen species,because the enzyme plays an important role in disproportioning superoxide radical(O2?),thus preventing the damaging effect of O2? or its derivatives on biomacromolecules.A seties of studies has focused on

Novel ions of quaternary ammonium halides in FDMS

Field desorption mass spectrometry exhibited novel ions [ Y-n H+n R ]+and [ Y-nH+nX]+as well as cluster ions [nY+(n-1)X-mH+mR]+and [nY+( n-1)X-mH+mX]+(n,m=0-3; X and Y represent the cation and anion moieties of quaternary ammonium halides),whose formation mechanism was discussed.