Microwave Spectrum of γ-Thiobutyrolactone

The microwave spectrum of γ-thiobutyrolactone has been observed and measured in the vibra-tional ground state and in several excited states of the ring-bending and ring-twisting modes. From the value of the μc component of the dipole moment and inertial-defect considerations the ring skeleton was shown to be non-planar. The average intensity ratio for the rotational transitions between the ground and excited vibrational states indicates that the first excited state of the ring-bending and ring-twisting modes are ~ 120 cm-1 and ~ 250 cm-1 above the ground state respectively. These two out-of-plane ring vibrations are essentially independent and the ring-bending vibration is governed by a nearly harmonic potential energy function. The components of the dipole moment were determined by the Stark effect to be μa = 3.770 ± 0.001 D, μb = 1.818 ± 0.044 D and μc = 0.832 ± 0.018 D, leading to μtotal = 4.268 ± 0.023 D. The rigidity of the γ-thiobutyrolactone ring is discussed in relation to those of related molecules.

Evaluation of Subcutaneous Proleukin (interleukin-2) in a Randomized International Trial (ESPRIT): geographical and gender differences in the baseline characteristics of participants

BACKGROUND

ESPRIT, is a phase III, open-label, randomized, international clinical trial evaluating the effects of subcutaneous recombinant interleukin-2 (rIL-2) plus antiretroviral therapy (ART) versus ART alone on HIV-disease progression and death in HIV-1-infected individuals with CD4+ T-cells > or =300 cells/microL.

OBJECTIVES

To describe the baseline characteristics of participants randomized to ESPRIT overall and by geographic location.

METHOD

Baseline characteristics of randomized participants were summarized by region.

RESULTS

4,150 patients were enrolled in ESPRIT from 254 sites in 25 countries. 41%, 27%, 16%, 11%, and 5% were enrolled in Europe, North America, South America, Asia, and Australia, respectively. The median age was 40 years, 81% were men, and 76%, 11%, and 9% were Caucasian, Asian, and African American or African, respectively. 44% of women enrolled (n = 769) were enrolled in Thailand and Argentina. Overall, 55% and 38% of the cohort acquired HIV through male homosexual and heterosexual contact, respectively. 25% had a prior history of AIDS-defining illness; Pneumocystis jirovecii pneumonia, M. tuberculosis, and esophageal candida were most commonly reported. Median nadir and baseline CD4+ T-cell counts were 199 and 458 cells/muL, respectively. 6% and 13% were hepatitis B or C virus coinfected, respectively. Median duration of antiretroviral therapy (ART) was 4.2 years; the longest median duration was in Australia (5.2 years) and the shortest was in Asia (2.3 years). 17%, 13%, and 69% of participants began ART before 1995, between 1996 and 1997, and from 1998 onward, respectively. 86% used ART from two or more ART classes, with 49% using a protease inhibitor-based regimen and 46% using a nonnucleoside reverse transcriptase inhibitor-based regimen. 78% had plasma HIV RNA below detection (<500 cp/mL).

CONCLUSION

ESPRIT has enrolled a diverse population of HIV-infected individuals including large populations of women and patients of African-American/African and Asian ethnicity often underrepresented in HIV research. As a consequence, the results of the study may have wide global applicability.

Adrenomedullin expression is up-regulated by ischemia-reperfusion in the cerebral cortex of the adult rat

Changes in the pattern of adrenomedullin expression in the rat cerebral cortex after ischemia-reperfusion were studied by light and electron microscopic immunohistochemistry using a specific antibody against human adrenomedullin (22-52). Animals were subjected to 30 min of oxygen and glucose deprivation in a perfusion model simulating global cerebral ischemia, and the cerebral cortex was studied after 0, 2, 4, 6, 8, 10 or 12 h of reperfusion. Adrenomedullin immunoreactivity was elevated in certain neuronal structures after 6-12 h of reperfusion as compared with controls. Under these conditions, numerous large pyramidal neurons and some small neurons were intensely stained in all cortical layers. The number of immunoreactive pre- and post-synaptic structures increased with the reperfusion time. Neurons immunoreactive for adrenomedullin presented a normal morphology whereas non-immunoreactive neurons were clearly damaged, suggesting a potential cell-specific protective role for adrenomedullin. The number and intensity of immunoreactive endothelial cells were also progressively elevated as the reperfusion time increased. In addition, the perivascular processes of glial cells and/or pericytes followed a similar pattern, suggesting that adrenomedullin may act as a vasodilator in the cerebrocortical circulation. In summary, adrenomedullin expression is elevated after the ischemic insult and seems to be part of CNS response mechanism to hypoxic injury.

Evidence for Efficient Unpromoted Regioselective Reactions of Vicinal and Non-Vicinal Diols

A 1965 publication from Angyal's laboratory reported that the cis-vicinal diol group of tetra-O-benzyl myo-inositol reacted regioselectively, sometimes exclusively, with acylating agents at the equatorial OH, but with alkylating agents at the axial OH. Recent reports by Fraser-Reid and coworkers showed that such selectivities were also found for the trans-1,3-diol of tetra-O-benzyl myo-inositol, as well as the C2-C4 hydroxyls of a di-O-allyl mannopyranoside. In addition, the latter workers reported that regioselectivities could be extended to glycosidation reactions. Thus, n-pentenyl ortho ester (NPOE) and 2-O-acyl n-pentenyl glycoside (NPGAC) donors reacted preferentially, if not exclusively, at the equatorial OH, whereas 2-O-alkyl counterparts (NPGALK) gave mixtures, usually with major glycosidation occuring at the axial OH. The present manuscript examines several vicinal diols, and reports that the NPOE and (NPGAC) donors frequently react at only one of the two hydroxy groups in good yield, whereas the corresponding benzylated donor (NPGALK) is less discriminating, and frequently gives lower yields. In a key experiment to examine the basis of the selectivity, it was found that the highly hindered C3 OH of 4,6-O-benzylidene methyl a-D-altropyranoside was selectively glycosylated with NPOE in 92% yield, thereby establishing that the glycosidation preference is not due to steric hindrance.

Comparative analysis of amyloid-beta chemical structure and amyloid plaque morphology of transgenic mouse and Alzheimer's disease brains

We have undertaken an integrated chemical and morphological comparison of the amyloid-beta (Abeta) molecules and the amyloid plaques present in the brains of APP23 transgenic (tg) mice and human Alzheimer's disease (AD) patients. Despite an apparent overall structural resemblance to AD pathology, our detailed chemical analyses revealed that although the amyloid plaques characteristic of AD contain cores that are highly resistant to chemical and physical disruption, the tg mice produced amyloid cores that were completely soluble in buffers containing SDS. Abeta chemical alterations account for the extreme stability of AD plaque core amyloid. The corresponding lack of post-translational modifications such as N-terminal degradation, isomerization, racemization, pyroglutamyl formation, oxidation, and covalently linked dimers in tg mouse Abeta provides an explanation for the differences in solubility between human AD and the APP23 tg mouse plaques. We hypothesize either that insufficient time is available for Abeta structural modifications or that the complex species-specific environment of the human disease is not precisely replicated in the tg mice. The appraisal of therapeutic agents or protocols in these animal models must be judged in the context of the lack of complete equivalence between the transgenic mouse plaques and the human AD lesions.

Relative replication fitness of a high-level 3'-azido-3'-deoxythymidine-resistant variant of human immunodeficiency virus type 1 possessing an amino acid deletion at codon 67 and a novel substitution (Thr-->Gly) at codon 69

The combination of an amino acid deletion at codon 67 (delta 67) and Thr-to-Gly change at codon 69 (T69G) in the reverse transcriptase (RT) of human immunodeficiency virus type 1 (HIV-1) is associated with high-level resistance to multiple RT inhibitors. To determine the relative contributions of the delta 67 and T69G mutations on viral fitness, we performed a series of studies of HIV replication using recombinant variants. A high-level 3'-azido-3'-deoxythymidine (AZT)-resistant variant containing delta 67 plus T69G/K70R/L74I/K103N/T215F/K219Q in RT replicated as efficiently as wild-type virus (Wt). In contrast, the construct without delta 67 exhibited impaired replication (23% of growth of Wt). A competitive fitness study failed to reveal any differences in replication rates between the delta 67+T69G/K70R/L74I/K103N/T215F/+ ++K219Q mutant and Wt. Evaluation of proviral DNA sequences over a 3-year period in a patient harboring the multiresistant HIV revealed that the T69G mutation emerged in the context of a D67N/K70R/T215F/K219Q mutant backbone prior to appearance of the delta 67 deletion. To assess the impact of this stepwise accumulation of mutations on viral replication, a series of recombinant variants was constructed and analyzed for replication competence. The T69G mutation was found to confer 2',3'-dideoxyinosine resistance at the expense of fitness. Subsequently, the development of the delta 67 deletion led to a virus with improved replication and high-level AZT resistance.

Conformation and stability of the hydrogen-bonded complex 6-oxabicyclo

The hydrogen-bonded complex between 6-oxabicyclo[3.1.0]hexane and hydrogen chloride was investigated by microwave spectroscopy in a supersonic jet. A dual flow pulsed valve was used to preclude chemical reaction between the monomers. Only the equatorial conformer was observed and the spectra of three isotopomers, (C5H8O, H35Cl), (C5H8O, H37Cl) and (C5H8O, D35Cl), were measured. The derived structure of the complex has Cs symmetry with the hydrogen chloride pointing to the domain of the equatorial lone pair of electrons at the oxygen atom. The three atoms involved in the hydrogen bond adopt a bent arrangement with a O...H distance of 1.77(4) A, a (O...H-Cl) angle of 115(4)degrees, and a deviation of 15.4(14)degrees of the hydrogen bond from collinearity. In agreement with the experimental results, ab initio calculations predict the equatorial form to be the most stable one.

The Ground and First Torsional States of CD(3)CHO

The rotational spectra for the ground and first excited torsional states v(t) = 0 and 1 in the frequency region of 8-254 GHz and the v(t) = 1 <-- 0 band high-resolution far-infrared spectrum of 2,2,2-d(3)-acetaldehyde (CD(3)CHO) were measured. We fitted a data set consisting of 1016 v(t) = 1 <-- 0 far-infrared lines together with 195 microwave lines in v(t) = 0 and 79 microwave lines in v(t) = 1 to near-experimental accuracy, using a global model from the earlier literature. The final fit includes lines with J </= 20 and requires 25 parameters to achieve root-mean-square deviations of 87 and 88 kHz for the microwave v(t) = 0 and 1 lines, respectively, and of 0.00048 cm(-1) for the far-infrared v(t) = 1-0 lines. This can be considered a good starting point for future analysis of CD(3)CHO. Copyright 1999 Academic Press.

The Millimeter-Wave Spectrum of 2,3-Dihydrofuran

The millimeter-wave spectrum of 2,3-dihydrofuran in the ground and five ring-puckering excited states has been measured in the frequency range 100-250 GHz. The ground and first ring-puckering excited states have been fitted to a two-state Hamiltonian including Coriolis coupling interaction. The determined energy difference of 18.684(7) cm-1 between these states and the a and b type coupling parameters are consistent with the ring-puckering potential function and the previously observed dependence of the centrifugal distortion constants DeltaJK, DeltaK, and deltaK. A small ring-puckering dependence of the quartic centrifugal distortion constants DeltaJ and deltaJ has been also observed. This dependence is well accounted for in terms of the ring-puckering potential function and the vibrational dependence of the rotational constants.

Sequence of the bchG gene from Chloroflexus aurantiacus: relationship between chlorophyll synthase and other polyprenyltransferases

The sequence of the Chloroflexus aurantiacus open reading frame thought to be the C. aurantiacus homolog of the Rhodobacter capsulatus bchG gene is reported. The BchG gene product catalyzes esterification of bacteriochlorophyllide a by geranylgeraniol-PPi during bacteriochlorophyll a biosynthesis. Homologs from Arabidopsis thaliana, Synechocystis sp. strain PCC6803, and C. aurantiacus were identified in database searches. Profile analysis identified three related polyprenyltransferase enzymes which attach an aliphatic alcohol PPi to an aromatic substrate. This suggests a broader relationship between chlorophyll synthases and other polyprenyltransferases.

Cyclization Reactions of Tethered Radicals Derived From 4-O-Substituted α-D-erythro-Octa-2,6-dienopyranosides: Stereoselective Access to Carbocycles and Branched-Chain Sugars

The chemo- and stereo- selectivities in the cyclization of tethered radicals, derived from α-D-erythro-octa-2,6-dienopyranosides, in which there is competition between 5-exo and 6-exo ring closures, have been examined. Use of silicon tethers resulted in a preferred 6-exo-trig addition. However, tethered mixed iodo acetals have shown an unprecedented relation between the stereogenic centre in the acetal and the preferred addition pathway. In addition, changes in the oxidation state at the termini of the olefins have a profound effect upon site selectivity, thus leading to 3-deoxy 3-C-substituted carbohydrates, off-template branched-chain sugars, or functionalized cyclopentanes.

Arsenic content of Spanish cows' milk determined by dry ashing hydride generation atomic absorption spectrometry

The arsenic content of cows' milk consumed in Spain was determined. A procedure using dry ashing hydride generation atomic absorption spectrometry was developed for the purpose. Experimental conditions for the destruction of organic matter were established and an interference study was carried out. The method developed has a detection limit of 0.1 ng/g, a relative SD of 5%, and a recovery (mean +/- CSI) of 100 +/- 4%. The accuracy of the method was checked by analysis of a certified sample of IAEA milk powder (mean +/- CSI: certified, 4.85 +/- 0.32 ng/g; found, 5.04 +/- 0.81 ng/g). The proposed procedure was used to analyse cows' milk samples. The extremely low arsenic levels found do not present toxicological problems.

Meconium ileus equivalent and Kawasaki syndrome. Case report

Kawasaki syndrome appeared after operation for meconium ileus equivalent in a 4-year-old child with cystic fibrosis. The course and management are described.