Phonon Laser in the Quantum Regime

We demonstrate a trapped-ion system with two competing dissipation channels, implemented independently on two ion species cotrapped in a Paul trap. By controlling coherent spin-oscillator couplings and optical pumping rates we explore the phase diagram of this system, which exhibits a regime analogous to that of a (phonon) laser but operates close to the quantum ground state with an average phonon number of n[over ¯]<10. We demonstrate phase locking of the oscillator to an additional resonant drive, and also observe the phase diffusion of the resulting state under dissipation by reconstructing the quantum state from a measurement of the characteristic function.

Post-treatment Mortality Among Patients With Tuberculosis: A Prospective Cohort Study of 10 964 Patients in Vietnam

BACKGROUND

Tuberculosis is the leading infectious cause of death. Steep reductions in tuberculosis-related mortality are required to realize the World Health Organization's "End Tuberculosis Strategy." However, accurate mortality estimates are lacking in many countries, particularly following discharge from care. This study aimed to establish the mortality rate among patients with pulmonary tuberculosis in Vietnam and to quantify the excess mortality in this population.

METHODS

We conducted a prospective cohort study among adult patients treated for smear-positive pulmonary tuberculosis in 70 clinics across Vietnam. People living in the same households were recruited as controls. Participants were re-interviewed and their survival was established at least 2 years after their treatment with an 8-month standardized regimen. The presence of relapse was established by linking identifying data on patients and controls to clinic registries. Verbal autopsies were performed. The cumulative mortality among patients was compared to that among a control population, adjusting for age and gender.

RESULTS

We enrolled 10964 patients and 25707 household controls. Among enrolled tuberculosis patients, 9% of patients died within a median follow-up period of 2.9 years: 342 (3.1%) during treatment and 637 (5.8%) after discharge. The standardized mortality ratio was 4.0 (95% confidence interval 3.7-4.2) among patients with tuberculosis, compared to the control population. Tuberculosis was the likely cause of death for 44.7% of these deceased patients.

CONCLUSIONS

Patients treated for tuberculosis had a markedly elevated risk of death, particularly in the post-treatment period. Interventions to reduce tuberculosis mortality must enhance the early detection of drug-resistance, improve treatment effectiveness, and address non-communicable diseases.

Efficient and Precise CRISPR/Cas9-Mediated MECP2 Modifications in Human-Induced Pluripotent Stem Cells

Patients with Rett syndrome (RTT) have severe mental and physical disabilities. The majority of RTT patients carry a heterozygous mutation in methyl-CpG binding protein 2 (MECP2), an X-linked gene encoding an epigenetic factor crucial for normal nerve cell function. No curative therapy for RTT syndrome exists, and cellular mechanisms are incompletely understood. Here, we developed a CRISPR/Cas9-mediated system that targets and corrects the disease relevant regions of the MECP2 exon 4 coding sequence. We achieved homologous recombination (HR) efficiencies of 20% to 30% in human cell lines and iPSCs. Furthermore, we successfully introduced a MECP2^R270X mutation into the MECP2 gene in human induced pluripotent stem cells (iPSCs). Consequently, using CRISPR/Cas9, we were able to repair such mutations with high efficiency in human mutant iPSCs. In summary, we provide a new strategy for MECP2 gene targeting that can be potentially translated into gene therapy or for iPSCs-based disease modeling of RTT syndrome.

The effects of bone marrow mononuclear cell transplantation on the quality of life of children with cerebral palsy

Background

Quality of life (QOL) is an important factor in evaluating the effectiveness of treatment in children with cerebral palsy (CP). The aim of this study was to evaluate the effects of autologous bone marrow mononuclear cells (BM MNCs) on the QOL of children with CP.

Methods

From December 2015 to December 2016, 30 children with CP aged from 2 to 15 years received two intrathecal infusions of BM MNCs, one at baseline and the other 3 months later, at Vinmec International Hospital. The motor function and muscle tone of the patients were evaluated using the Gross Motor Function Measure (GMFM)-88 and Modified Ashworth Score, respectively. Their QOL was assessed at baseline and 6 months after the first BM MNC transplant using the Vietnamese version of the Cerebral Palsy Quality of Life Questionnaire for children (CP QOL-Child)–the parental proxy report, which comprises seven domains. Nineteen mothers (mean age: 32.9±4.9 years) and 11 fathers (mean age: 36.1±6.8 years) were invited to complete the CP QOL-Child assessment before and after the transplantations, Paired t-tests and multivariate regression analyses were used to evaluate the changes in QOL and GMFM scores and to identify the key factors correlated with the QOL score.

Results

Significant changes were observed in the children’s gross motor function and muscle spasticity, as evidenced by the GMFM-88 total score, scores for each of its domains, the GMFM-66 percentile and the muscle tone (P < 0.001). Six months after the transplantations, the QOL scores of children with CP were markedly increased (P < 0.001) for all the domains, except for the domain of access to services. In the multivariate regression analysis, significant associations were found between higher age of children and higher QOL except for feeling about functioning and pain and impact of disability domains. Gross Motor Function Classification System (GMFCS) level was negatively correlated with the score of pain and impact of disability domain, while the GMFM-88 scores were positively correlated with the QOL in terms of feelings about functioning and family health domain (P < 0.05).

Conclusion

The QOL of the children with CP was noticeably improved 6 months after BM MNC transplantation and was accompanied by improvements in gross motor function and muscle tone.

Trial registration

ClinicalTrials.gov Identifier: NCT02574923. Registered on October 14, 2015.

DS1/OsEMF1 interacts with OsARF11 to control rice architecture by regulation of brassinosteroid signaling

BACKGROUND

Plant height and leaf angle are important determinants of yield in rice (Oryza sativa L.). Genes involved in regulating plant height and leaf angle were identified in previous studies; however, there are many remaining unknown factors that affect rice architecture.

RESULTS

In this study, we characterized a dwarf mutant named ds1 with small grain size and decreased leaf angle,selected from an irradiated population of ssp. japonica variety Nanjing35. The ds1 mutant also showed abnormal floral organs. ds1 plants were insensitive to BL treatment and expression of genes related to BR signaling was changed. An F₂ population from a cross between ds1 and indica cultivar 93-11 was used to fine map DS1 and to map-based clone the DS1 allele, which encoded an EMF1-like protein that acted as a transcriptional regulator. DS1 was constitutively expressed in various tissues, and especially highly expressed in young leaves, panicles and seeds. We showed that the DS1 protein interacted with auxin response factor 11 (OsARF11), a major transcriptional regulator of plant height and leaf angle, to co-regulate D61/OsBRI1 expression. These findings provide novel insights into understanding the molecular mechanisms by which DS1 integrates auxin and brassinosteroid signaling in rice.

CONCLUSION

The DS1 gene encoded an EMF1-like protein in rice. The ds1 mutation altered the expression of genes related to BR signaling, and ds1 was insensitive to BL treatment. DS1 interacts with OsARF11 to co-regulate OsBRI1 expression.

Development of real-time PCR for detection and quantitation of Streptococcus parauberis

Streptococcus parauberis is an increasing threat to aquaculture of olive flounder, Paralichthys olivaceus Temminck & Schlegel, in South Korea. We developed a real-time polymerase chain reaction (PCR) method using the TaqMan probe assay to detect and quantify S. parauberis by targeting the gyrB gene sequences, which are effective for molecular analysis of the genus Streptococcus. Our real-time PCR assay is capable of detecting 10 fg of genomic DNA per reaction. The intra- and interassay coefficient of variation (CV) values ranged from 0.42-1.95%, demonstrating that the assay has good reproducibility. There was not any cross-reactivity to Streptococcus iniae or to other streptococcal/lactococcal fish pathogens, such as S. agalactiae and Lactococcus garvieae, indicating that the assay is highly specific to S. parauberis. The results of the real-time PCR assay corresponded well to those of conventional culture assays for S. parauberis from inoculated tissue homogenates (r = 0.957; P < 0.05). Hence, this sensitive and specific real-time PCR is a valuable tool for diagnostic quantitation of S. parauberis in clinical samples.

Microwaves Probe Dipole Blockade and van der Waals Forces in a Cold Rydberg Gas

We show that microwave spectroscopy of a dense Rydberg gas trapped on a superconducting atom chip in the dipole blockade regime reveals directly the dipole-dipole many-body interaction energy spectrum. We use this method to investigate the expansion of the Rydberg cloud under the effect of repulsive van der Waals forces and the breakdown of the frozen gas approximation. This study opens a promising route for quantum simulation of many-body systems and quantum information transport in chains of strongly interacting Rydberg atoms.

Mesenteric lymphatic vessels adapt to mesenteric venous hypertension by becoming weaker pumps

Lymphangions, the segments of lymphatic vessels between two adjacent lymphatic valves, actively pump lymph. Acute changes in transmural pressure and lymph flow have profound effects on lymphatic pump function in vitro. Chronic changes in pressure and flow in vivo have also been reported to lead to significant changes in lymphangion function. Because changes in pressure and flow are both cause and effect of adaptive processes, characterizing adaptation requires a more fundamental analysis of lymphatic muscle properties. Therefore, the purpose of the present work was to use an intact lymphangion isovolumetric preparation to evaluate changes in mesenteric lymphatic muscle mechanical properties and the intracellular Ca(2+) in response to sustained mesenteric venous hypertension. Bovine mesenteric veins were surgically occluded to create mesenteric venous hypertension. Postnodal mesenteric lymphatic vessels from mesenteric venous hypertension (MVH; n = 6) and sham surgery (Sham; n = 6) animals were isolated and evaluated 3 days after the surgery. Spontaneously contracting MVH vessels generated end-systolic active tension and end-diastolic active tension lower than the Sham vessels. Furthermore, steady-state active tension and intracellular Ca(2+) concentration levels in response to KCl stimulation were also significantly lower in MVH vessels compared with those of the Sham vessels. There was no significant difference in passive tension in lymphatic vessels from the two groups. Taken together, these results suggest that following 3 days of mesenteric venous hypertension, postnodal mesenteric lymphatic vessels adapt to become weaker pumps with decreased cytosolic Ca(2+) concentration.

First Report of Geosmithia morbida on English Walnut and its Paradox Rootstock in California

Geosmithia morbida, the causal agent of thousand cankers disease (TCD), is vectored by the walnut twig beetle (WTB), Pityophthorus juglandis, causing decline in eastern black walnut, Juglans nigra (4), and canker development on many Juglans species (5). In the summer of 2012, a survey for TCD incidence in English walnut, J. regia, in orchards in California identified many trees with WTB activity and characteristic TCD symptoms. Both the J. regia scion and its Paradox hybrid rootstock (J. hindsii× J. regia) were affected. In some cases, trees exhibited bleeding on the bark surface from WTB entrance holes. Removal of the outer bark revealed cankers in the phloem around the WTB galleries. Two samples were taken from scions and three samples were collected from rootstocks of trees in orchards in northern California. Pieces (~3 to 4 mm²) of symptomatic tissue were placed in acidified potato dextrose agar (APDA), and the plates were incubated for 4 to 5 days at 30°C. Samples exhibiting fungal growth similar in morphology to G. morbida were transferred to PDA plates to obtain pure cultures and then processed to obtain single-spore cultures. Culture morphology for five single-spore isolates (Gm103, Gm104, Gm105, Gm107, and Gm108) was similar to that described by Kolařík et al. (4) for G. morbida. Conidiophores were penicillate and verrucose. Conidia were narrowly cylindrical, 5.2 ± 0.06 × 2.2 ± 0.04 μm (n = 50). Single-spore isolates were then grown in 1% yeast extract glucose liquid culture for 7 to 10 days. DNA was extracted and the ITS region was amplified, including the 5.8S region by using primers ITS1F/ITS4. Sequences were assembled and deposited in GenBank under accessions KJ664793 to KJ664797. Sequences were compared to those in GenBank; all sequences matched (99 to 100% identity) the ITS sequences of G. morbida strain CBS 124663. Pathogenicity tests were performed on 28-cm-long detached branches of J. regia. Four branches per isolate were inoculated with a 5-mm-diameter mycelial plug from a 2-week-old culture. Branches were incubated at room temperature (23 ± 2°C) in a humidified container for 3 weeks, and then canker lengths were measured. Pieces of the cankered area were placed in APDA and incubated as described above with G. morbida re-isolated from the cankers for all of the isolates, completing Koch's postulates. Average canker lengths ranged from 48.6 ± 4.3 to 72.1 ± 7.1 mm. Re-isolated G. morbida exhibited the same growth and reproductive structure morphology in culture on PDA as the original cultures. TCD in association with WTB has been observed in California English walnut orchards since 2008 (1,2,3). However, this is the first report for completion of Koch's postulates and morphological and molecular confirmation of G. morbida in J. regia and the Paradox rootstock, the predominant rootstock used in commercial orchards. TCD is a concern to the walnut industry in California with over 245,000 bearing acres reported in 2012. References: (1) M. Flint et al. CAPCA Adviser 8:36, 2010. (2) A. D. Graves et al. Walnut Twig Beetle and Thousand Cankers Disease: Field Identification Guide. UC-IPM website publication, http://www.ipm.ucdavis.edu/PDF/MISC/thousand_cankers_field_guide.pdf , 2009. (3) J. Hasey et al. (Abstr.) Phytopathology 100:S48, 2010. (4) M. Kolařík et al. Mycologia 103:325, 2011. (5) C. Utley et al. Plant Dis. 97:601, 2013.

Complex transposition repair with aortic arch hypoplasia: a simple technique

A modified technique of interdigitating aortic arch reconstruction was used successfully to treat 8 patients with complex congenital heart disease including transposition of the great arteries, ventricular septal defect, or Taussig-Bing anomalies combined with aortic arch hypoplasia and coarctation of the aorta, without the need for homograft tissue.

Adaptation of mesenteric lymphatic vessels to prolonged changes in transmural pressure

In vitro studies have revealed that acute increases in transmural pressure increase lymphatic vessel contractile function. However, adaptive responses to prolonged changes in transmural pressure in vivo have not been reported. Therefore, we developed a novel bovine mesenteric lymphatic partial constriction model to test the hypothesis that lymphatic vessels exposed to higher transmural pressures adapt functionally to become stronger pumps than vessels exposed to lower transmural pressures. Postnodal mesenteric lymphatic vessels were partially constricted for 3 days. On postoperative day 3, constricted vessels were isolated, and divided into upstream (UP) and downstream (DN) segment groups, and instrumented in an isolated bath. Although there were no differences between the passive diameters of the two groups, both diastolic diameter and systolic diameter were significantly larger in the UP group than in the DN group. The pump index of the UP group was also higher than that in the DN group. In conclusion, this is the first work to report how lymphatic vessels adapt to prolonged changes in transmural pressure in vivo. Our results suggest that vessel segments upstream of the constriction adapt to become both better fluid conduits and lymphatic pumps than downstream segments.

Novel homozygous p.Y395X mutation in the CYP11B1 gene found in a Vietnamese patient with 11β-hydroxylase deficiency

CONTEXT

The deficiency of steroid 11β-hydroxylase is caused by mutations in the CYP11B1 gene and is the second major form of congenital adrenal hyperplasia associated with hypertension.

OBJECTIVE

The objective of this study was to screen the CYP11B1 gene for mutations in one Vietnamese male suffering from congenital adrenal hyperplasia.

PATIENT

The patient (46,XY) had congenital adrenal hyperplasia. The clinical manifestations presented precocious puberty, hyper-pigmentation and high blood pressure at 4 years.

RESULTS

The patient was a homozygous carrier of a novel mutation located in exon 7 containing a premature stop codon instead of tyrosine at 395 (p.Y395X).

CONCLUSION

We have identified a novel mutant of the CYP11B1 gene in one Vietnamese family associated with phenotypes of congenital adrenal hyperplasia. The mutant gene p.Y395X produces a truncated form of the polypeptide and abolishes the enzyme activities, leading to a severe phenotype of congenital adrenal hyperplasia.

On the role of surface roughness in the corrosion of pure magnesium in vitro

The relationship between surface roughness and degradation behavior in magnesium (Mg) biomaterials is still a controversial issue. This study aims to clarify the relationship between surface roughness and corrosion rate of pure Mg. Pure Mg samples with surface roughness values (Ra) of 0.59, 2.68, and 9.12 μm were cast using an indirect solid-free form fabrication method. The in vitro corrosion behavior was evaluated using hydrogen evolution, mass loss, potentiodynamic polarization, and electrochemical impedance spectroscopy. It was confirmed that surface roughness had a significant influence on the corrosion rate of pure Mg, with increasing roughness resulting in an accelerated corrosion rate. However, pitting corrosion was not observed, suggesting that surface roughness does not affect the pitting potential of Mg.

RET mutational spectrum in Hirschsprung disease: evaluation of 601 Chinese patients

Rare (RVs) and common variants of the RET gene contribute to Hirschsprung disease (HSCR; congenital aganglionosis). While RET common variants are strongly associated with the commonest manifestation of the disease (males; short-segment aganglionosis; sporadic), rare coding sequence (CDS) variants are more frequently found in the lesser common and more severe forms of the disease (females; long/total colonic aganglionosis; familial).

Here we present the screening for RVs in the RET CDS and intron/exon boundaries of 601 Chinese HSCR patients, the largest number of patients ever reported. We identified 61 different heterozygous RVs (50 novel) distributed among 100 patients (16.64%). Those include 14 silent, 29 missense, 5 nonsense, 4 frame-shifts, and one in-frame amino-acid deletion in the CDS, two splice-site deletions, 4 nucleotide substitutions and a 22-bp deletion in the intron/exon boundaries and 1 single-nucleotide substitution in the 5′ untranslated region. Exonic variants were mainly clustered in RET the extracellular domain. RET RVs were more frequent among patients with the most severe phenotype (24% vs. 15% in short-HSCR). Phasing RVs with the RET HSCR-associated haplotype suggests that RVs do not underlie the undisputable association of RET common variants with HSCR. None of the variants were found in 250 Chinese controls.

Genotype X/C recombinant (putative genotype I) of hepatitis B virus is rare in Hanoi, Vietnam--genotypes B4 and C1 predominate

There are eight known genotypes of hepatitis B virus, A-H, and several subgenotypes, with rather well-defined geographic distributions. HBV genotypes were evaluated in 153 serum samples from Hanoi, Vietnam. Of the 87 samples that could be genotyped, genotype B was found in 67 (77%) and genotype C in 19 (22%). All genotype C strains were of subgenotype C1, and the majority of genotype B strains were B4, while a few were B2. The genotype X/C recombinant strain, identified previously in Swedish patients of indigenous Vietnamese origin, was found in one sample. This variant, proposed to be classified as genotype I, has been found recently also by others in Vietnam and Laos. The current study indicates that the genotype X/C recombinant may represent approximately 1% of the HBV strains circulating in Vietnam.

HOx radical regeneration in the oxidation of isoprene

We propose, and quantify from first principles, two novel HO(x)-regenerating unimolecular reactions in isoprene oxidation, which are estimated to yield in pristine tropical forest conditions about 0.7 HO(2) and 0.03 OH radicals per isoprene oxidized; it is further argued that the photolabile coproduct of HO(2) can be a major source of OH, with a yield of the order of 1. The newly proposed chemistry could provide a rationalization for the unexpectedly high OH concentrations often observed in forested environments, such as over the Amazon forest in the recent Gabriel campaign.

Laparoscopic and transanal approach for rectal atresia: a novel alternative

AIM

The aim of this study is to present the details and outcomes of laparoscopic and transanal approach in the management of rectal atresia.

PATIENTS

Two female patients with rectal atresia were operated upon using laparoscopic and transanal approach. There were no intraoperative and postoperative complications. Follow-up at 5 and 4 months, respectively, after closure of colostomy has shown both patients with good fecal continence.

CONCLUSION

Laparoscopic and transanal approach is a novel and good alternative to the current surgical techniques in the management of rectal atresia.

[Predictive factors of dengue shock syndrome at the children Hospital No. 1, Ho-chi-Minh City, Vietnam]

The dengue shock syndrome (DSS) is primarily a complication of dengue haemorrhagic fever (DHF) among children in South East Asia. A case-control study was carried out at the children hospital no 1 (Ho-Chi-Minh City, Vietnam) in May-July 2005, to identify the predictive factors of the DSS among 1-15 year patients with DHE Forty consecutive admitted cases and forty controls were studied. The associated features of DSS were the 7-12 year age group and the re-infection by the dengue virus. The vaccination against the Japanese encephalitis B was not associated statistically significantly with the shock syndrome. The clinical predictors of DSS gathered an abdominal tenderness, an hepatomegaly, a lethargy, a cold extremity presentation. DSS associated laboratory features were a value of hematocrit a 50 % and a platelet cell count < or = 75,000/mm3.

Thoracoscopic repair for congenital diaphragmatic hernia: lessons from 45 cases

PURPOSE

To describe the surgical technique, initial results, and overview indications of thoracoscopic repair of congenital diaphragmatic hernia (CDH).

MATERIALS AND METHODS

A retrospective review was undertaken of patients with CDH who underwent thoracoscopic repair by the same surgeon from January 2001 to January 2005. Patients underwent surgery under general anesthesia. Reduction of the hernia contents was carried out using 1 optical trocar and 2 operating trocars. Pleural insufflation with carbon dioxide was maintained at a pressure of 2 to 4 mm Hg. The hernia defect was repaired using nonabsorbable interrupted sutures with extracorporeal knots.

RESULTS

There were 45 patients, including 29 boys and 16 girls. Among 19 newborn patients, there were 13 patients younger than 7 days. The other 26 patients were infants and elders. The hernia was located in the left side in 37 patients and in the right side in 8 patients. The mean operative time was 54 minutes. Conversion was required in 4 patients. There were no complications. However, there were 2 postoperative deaths.

CONCLUSIONS

Thoracoscopic repair is feasible and safe for children with CDH, including selective newborn. The technique causes minimal trauma, results in good respiratory function, and promotes early recovery.

Photodissociation of benzene under collision-free conditions: an ab initio/Rice-Ramsperger-Kassel-Marcus study

The ab initio/Rice-Ramsperger-Kassel-Marcus (RRKM) approach has been applied to investigate the photodissociation mechanism of benzene at various wavelengths upon absorption of one or two UV photons followed by internal conversion into the ground electronic state. Reaction pathways leading to various decomposition products have been mapped out at the G2M level and then the RRKM and microcanonical variational transition state theories have been applied to compute rate constants for individual reaction steps. Relative product yields (branching ratios) for C(6)H(5)+H, C(6)H(4)+H(2), C(4)H(4)+C(2)H(2), C(4)H(2)+C(2)H(4), C(3)H(3)+C(3)H(3), C(5)H(3)+CH(3), and C(4)H(3)+C(2)H(3) have been calculated subsequently using both numerical integration of kinetic master equations and the steady-state approach. The results show that upon absorption of a 248 nm photon dissociation is too slow to be observable in molecular beam experiments. In photodissociation at 193 nm, the dominant dissociation channel is H atom elimination (99.6%) and the minor reaction channel is H(2) elimination, with the branching ratio of only 0.4%. The calculated lifetime of benzene at 193 nm is about 11 micros, in excellent agreement with the experimental value of 10 micros. At 157 nm, the H loss remains the dominant channel but its branching ratio decreases to 97.5%, while that for H(2) elimination increases to 2.1%. The other channels leading to C(3)H(3)+C(3)H(3), C(5)H(3)+CH(3), C(4)H(4)+C(2)H(2), and C(4)H(3)+C(2)H(3) play insignificant role but might be observed. For photodissociation upon absorption of two UV photons occurring through the neutral "hot" benzene mechanism excluding dissociative ionization, we predict that the C(6)H(5)+H channel should be less dominant, while the contribution of C(6)H(4)+H(2) and the C(3)H(3)+C(3)H(3), CH(3)+C(5)H(3), and C(4)H(3)+C(2)H(3) radical channels should significantly increase.

Three-dimensional model of the pore form of anthrax protective antigen. Structure and biological implications

Although pore formation by protective antigen (PA) is critical to cell intoxication by anthrax toxin (AT), the structure of the pore form of PA (the PA63 pore) has not been determined. Hence, in this study, the PA63 pore was modeled using the X-ray structures of monomeric PA and heptameric alpha-hemolysin (alpha-HL) as templates. The PA63 pore model consists of two weakly associated domains, namely the cap and stem domains. The ring-like cap domain has a length of 80 A and an outside diameter of 120 A, while the cylinder-like stem domain has a length of 100 A and outside diameter of approximately 28 A. This provides the PA63 pore model with a length of 180 A. Based on experimental results, the channel in the PA63 pore model was built to have a minimum diameter of ~12 A, depending on side chain conformations. Because of its large size and structural complexity, the all-atom model of the PA63 pore is the end-stage construction of four separate modeling projects described herein. The final model is consistent with published experimental results, including mutational analysis and channel conductance experiments. In addition, the model was energetically and hydropathically refined to optimize molecular packing within the protomers and at the protomer-protomer interfaces. By providing atomic detail to biochemical and biophysical data, the PA63 pore model may afford new insights into the binding mode of PA on the membrane surface, the prepore-pore transition, and the mechanism of cell entry by anthrax toxin.

Theoretical and Experimental Study of the Product Branching in the Reaction of Acetic Acid with OH Radicals

The product distribution of the reaction of acetic acid, CH(3)COOH, with hydroxyl radicals, OH, was studied experimentally and theoretically. Mass-spectrometric measurements at 290 K and 2 Torr of He of the CO(2) yield versus the loss of acetic acid yielded a branching fraction of 64 +/- 14% for the abstraction of the acidic hydrogen as follows: CH(3)COOH + OH --> CH(3)COO + H(2)O --> CH(3) + CO(2) + H(2)O. A quantum chemical and theoretical kinetic analysis showed that the abstraction of the acidic hydrogen is enhanced relative to the abstraction of -CH(3) hydrogens because of the formation of a strong pre-reactive H-bonded complex, where the H-bonds are retained in the H-abstraction transition state. The potential energy surface of the reaction is explored in detail, and the reaction products of the individual channels are identified. The theoretical product branching is found to be critically dependent on the energetic and rovibrational differences between the H-abstraction transition states.

Avian influenza A (H5N1) in 10 patients in Vietnam

BACKGROUND

Recent outbreaks of avian influenza A (H5N1) in poultry throughout Asia have had major economic and health repercussions. Human infections with this virus were identified in Vietnam in January 2004.

METHODS

We report the clinical features and preliminary epidemiologic findings among 10 patients with confirmed cases of avian influenza A (H5N1) who presented to hospitals in Ho Chi Minh City and Hanoi, Vietnam, in December 2003 and January 2004.

RESULTS

In all 10 cases, the diagnosis of influenza A (H5N1) was confirmed by means of viral culture or reverse transcriptase-polymerase chain reaction with primers specific for H5 and N1. None of the 10 patients (mean age, 13.7 years) had preexisting medical conditions. Nine of them had a clear history of direct contact with poultry (median time before onset of illness, three days). All patients presented with fever (temperature, 38.5 to 40.0 degrees C), respiratory symptoms, and clinically significant lymphopenia (median lymphocyte count, 700 per cubic millimeter). The median platelet count was 75,500 per cubic millimeter. Seven patients had diarrhea. In all patients, there were marked abnormalities on chest radiography. There was no definitive evidence of human-to-human transmission. Eight patients died, one patient has recovered, and one is recovering.

CONCLUSIONS

Influenza A (H5N1) infection, characterized by fever, respiratory symptoms, and lymphopenia, carries a high risk of death. Although in all 10 cases the infection appears to have been acquired directly from infected poultry, the potential exists for genetic reassortment with human influenzaviruses and the evolution of human-to-human transmission. Containment of influenza A (H5N1) in poultry throughout Asia is therefore urgently required.

A combined crossed molecular beam and ab initio investigation of C2 and C3 elementary reactions with unsaturated hydrocarbons--pathways to hydrogen deficient hydrocarbon radicals in combustion flames

Crossed molecular beam experiments on dicarbon and tricarbon reactions with unsaturated hydrocarbons acetylene, methylacetylene, and ethylene were performed to investigate the dynamics of channels leading to hydrogen-deficient hydrocarbon radicals. In the light of the results of new ab initio calculations, the experimental data suggest that these reactions are governed by an initial addition of C2/C3 to the pi molecular orbitals forming highly unsaturated cyclic structures. These intermediates are connected via various transition states and are suggested to ring open to chain isomers which decompose predominantly by displacement of atomic hydrogen, forming C4H, C5H, HCCCCCH2, HCCCCCCH3, H2CCCCH and H2CCCCCH. The C2(1 sigma g+) + C2H4 reaction has no entrance barrier and the channel leading to the H2CCCCH product is strongly exothermic. This is in strong contrast with the C3(1 sigma g+) + C2H4 reaction as this is characterized by a 26.4 kJ mol-1 threshold to form a HCCCCCH2 isomer. Analogous to the behavior with ethylene, preliminary results on the reactions of C2 and C3 with C2H2 and CH3CCH showed the H-displacement channels of these systems to share many similarities such as the absence/presence of an entrance barrier and the reaction mechanism. The explicit identification of the C2/C3 vs. hydrogen displacement demonstrates that hydrogen-deficient hydrocarbon radicals can be formed easily in environments like those of combustion processes. Our work is a first step towards a systematic database of the intermediates and the reaction products which are involved in this important class of reactions. These findings should be included in future models of PAH and soot formation in combustion flames.

Commensurate and incommensurate hydrogen bonds. An exercise in crystal engineering

Ureas characteristically form one-dimensional hydrogen-bonded alpha-networks with a repeat distance of about 4.60 A. Oxamides form similar alpha-networks with a longer 5.05 A repeat distance. The urea of glycine and the oxamide of glycine were each cocrystallized with a series of four bipyridines, including two urea derivatives and two oxamide derivatives. This series of eight cocrystals was studied by X-ray diffraction in order to see what would happen when molecules that would normally form alpha-networks with incommensurate distances were forced into the same crystal. The two all-urea crystals and the two all-oxamide crystals contained the expected alpha-networks with repeat distances in accordance with normal urea or oxamide values. Four of the crystals were mixed, containing both oxamide and urea molecules. Three consisted of two-dimensional beta-networks with alternating parallel urea and oxamide subnetworks. The repeat distances averaged 4.87 A, a value close to the value expected for oxamides, but shorter than any previously observed examples. In the fourth mixed crystal, the urea alpha-network formed with a normal urea repeat distance, but the oxamide network did not form, the oxamide adopting an unusual molecular conformation that maximizes intramolecular hydrogen bonds instead.

Severe hypoxia specifically downregulates hepatocyte nuclear factor-4 gene expression in HepG2 human hepatoma cells

The liver is one of the organs in which hypoxia helps to regulate gene expression under normal physiological conditions and in diseases such as cirrhosis and cancer. We postulated that the expression/activity of some of the 'liver-enriched' transcription factors, which control liver-specific genes, was sensitive to hypoxia. We tested hepatocyte nuclear factor-1 (HNF-1), HNF-3 and HNF-4, which play key roles in differentiation, development and hepatic gene expression, using HepG2 human hepatoma cells cultured under hypoxic conditions. Severe hypoxia/anoxia downregulated HNF-4 DNA-binding activity while DNA-binding activity of HNF-1 and HNF-3 remained unaffected. These hypoxic conditions also strongly and specifically decreased cell contents of HNF-4 protein, indicating that the decrease in HNF-4 DNA-binding activity was due to the lower amount of protein and not to decreased DNA-binding affinity. Northern analysis indicated that the expression of the hnf-4 gene was also downregulated in HepG2 cells cultured under hypoxic conditions. These results provide evidence that hypoxic stress triggers a cascade of events that inhibits the transactivation potential of HNF-4 in HepG2 cells. This step may be crucial in modulating the expression of a subset of liver genes that are targets for this nuclear receptor. This relationship provides a new route for the investigation of the effects of hypoxia on the liver cell.

Structures of an unliganded neurophysin and its vasopressin complex: implications for binding and allosteric mechanisms

The structures of des 1-6 bovine neurophysin-II in the unliganded state and as its complex with lysine vasopressin were determined crystallographically at resolutions of 2.4 A and 2.3 A, respectively. The structure of the protein component of the vasopressin complex was, with some local differences, similar to that determined earlier of the full-length protein complexed with oxytocin, but relatively large differences, probably intrinsic to the hormones, were observed between the structures of bound oxytocin and bound vasopressin at Gln 4. The structure of the unliganded protein is the first structure of an unliganded neurophysin. Comparison with the liganded state indicated significant binding-induced conformational changes that were the largest in the loop region comprising residues 50-58 and in the 7-10 region. A subtle binding-induced tightening of the subunit interface of the dimer also was shown, consistent with a role for interface changes in neurophysin allosteric mechanism, but one that is probably not predominant. Interface changes are suggested to be communicated from the binding site through the strands of beta-sheet that connect these two regions, in part with mediation by Gly 23. Comparison of unliganded and liganded states additionally reveals that the binding site for the hormone alpha-amino group is largely preformed and accessible in the unliganded state, suggesting that it represents the initial site of hormone protein recognition. The potential molecular basis for its thermodynamic contribution to binding is discussed.

Effects of diabetes insipidus mutations on neurophysin folding and function

Mechanisms underlying the pathogenicity of diabetes insipidus mutations were probed by studying their effects on the properties of bovine oxytocin-related neurophysin. The mutations G17V, DeltaE47, G57S, G57R, and C67STOP were each shown to have structural consequences that would diminish the conformational stability and folding efficiency of the precursors in which they were incorporated, and factors contributing to the origins of these property changes were identified. Effects of the mutations on dimerization of the folded proteins were similarly analyzed. The projected relative impact of the above mutations on precursor folding properties qualitatively parallels the reported relative severity of their effects on the biological handling of the human vasopressin precursor, but quantitative differences between thermodynamic effects and biological impact are noted and explored. The sole mutation for which no clear thermodynamic basis was found for its pathogenicity was 87STOP, suggesting that the region of the precursor deleted by this mutation plays a role in targeting independent from effects on folding, or participates in stabilizing interactions unique to the human vasopressin precursor.

The epidemiology and disease burden of rotavirus in Vietnam: sentinel surveillance at 6 hospitals

The disease burden of rotavirus diarrhea in Vietnam was assessed by surveillance of children <5 years old who were hospitalized for diarrhea at 3 centers in the north and 3 centers in the south. Rotavirus was identified in 56% (range, 47%-60%) of the 5768 patients surveyed between July 1998 and June 2000. G-typing of the first 224 strains indicated that only 2% were non-typeable, 9% were in mixed infections, and the remainder were of the common serotypes G1, G2, G3, G4, and G9. In Vietnam, diarrhea accounts for 9880 deaths per year, which is approximately 15% of all deaths among children <5 years old, or 6.5 deaths per 1000 children. If even 50% of these diarrhea-related deaths in Vietnam were due to rotavirus, the number would represent 4%-8% of all deaths among children <5 years old, 2700-5400 rotavirus-related deaths per year, and 1 death per 280-560 children during the first 5 years of life. Thus, the disease burden of rotavirus in Vietnam is substantial, and programs to encourage the use of oral rehydration should be encouraged while efforts to develop vaccines continue.

Modulation of dimerization, binding, stability, and folding by mutation of the neurophysin subunit interface

Bovine neurophysins, which have typically served as the paradigm for neurophysin behavior, are metastable in their disulfide-paired folded state and require ligand stabilization for efficient folding from the reduced state. Studies of unliganded porcine neurophysin (oxytocin-associated class) demonstrated that its dimerization constant is more than 90-fold greater than that of the corresponding bovine protein at neutral pH and showed that the increased dimerization constant is accompanied by an increase in stability sufficient to allow efficient folding of the reduced protein in the absence of ligand peptide. Using site-specific mutagenesis of the bovine protein and expression in Escherichia coli, the functional differences between the bovine and porcine proteins were shown to be attributable solely to two subunit interface mutations in the porcine protein, His to Arg at position 80 and Glu to Phe at position 81. Mutation of His-80 alone to Arg had a relatively small impact on dimerization, while mutation to either Glu or Asp markedly reduced dimerization in the unliganded state, albeit with apparent retention of the positive linkage between dimerization and binding. Comparison of the peptide-binding constants of the different mutants additionally indicated that substitution of His-80 led to modifications in binding affinity and specificity that were independent of effects on dimerization. The results demonstrate the importance of the carboxyl domain segment of the subunit interface in modulating neurophysin properties and suggest a specific contribution of the energetics of ligand-induced conformational change in this region to the overall thermodynamics of binding. The potential utility to future studies of the self-folding and monomeric mutants generated by altering the interface is noted.

Tumor necrosis factor alpha levels in plasma and whole-blood culture in dengue-infected patients: relationship between virus detection and pre-existing specific antibodies

The pathogenesis of dengue hemorrhagic fever (DHF) is not well known, but the role of host factors has been suggested. The level of immunoreactive circulating and cell-generated tumor necrosis factor alpha (TNF alpha) was studied in 35 patients with DHF; its relationship with virus isolation and/or genome detection by reverse transcription polymerase chain reaction (RT-PCR) and specific antibodies were detected by hemagglutination inhibition (HI). Large variation of TNF alpha plasma levels was obtained in dengue-infected patients at the same stage of the disease and at the same day after infection. Most of the patients (14 out of 17 patients) who displayed augmented spontaneous in vitro production of TNF alpha by heparinized whole-blood culture compared with controls also had elevated levels of TNF alpha in the plasma. The TNF alpha values in lipopolysaccharide and phytohemagglutinin heparinized whole-blood cultures were not higher in patients than in controls, but low TNF alpha levels were obtained in three out of 30 patients. An inverse correlation was observed between spontaneous in vitro TNF alpha production and viral replication, which raises the issue of the antiviral effect of TNF alpha in dengue infection. The results do not support the hypothesis of the role of antibody-dependent enhancement giving rise to increased viremic titers and production of TNF alpha in patients. The present study demonstrates the activation of the TNF alpha-producing cells in dengue-infected patients and suggests further investigation to define the mechanism and the role of TNF alpha in the pathogenesis of dengue virus infection.

Vascular endothelial dysfunction contributes to myocardial depression in ischemia-reperfusion in the rat

Endocardial and vascular myocardial capillary endothelium has been shown to modulate the contractile characteristics of myocardium by altering myofibrillar affinity for calcium. Although the release of endothelial-derived substances that modify myocardial contractility has been shown to be altered in certain physiologic and pathologic situations, until now no study has evaluated whether the direct modulatory effects of endothelium on its subjacent myocardium were altered in pathologic situations and contributed to loss of contractile function. This study was designed to evaluate whether the direct contractile modulatory effects of endocardial and (or) vascular endothelium were altered and whether these alterations contributed to contractile dysfunction in a model of ischemia-reperfusion. Sixty-two perfused rat hearts as Langendorff preparations were randomized to no intervention, intracoronary Triton X100 injection (to render vascular endothelium dysfunctional), ischemia (30 min)-reperfusion (20 min), and ischemia-reperfusion followed by intracoronary Triton X100 injection. Coronary endothelial-dependent vascular reactivity and vascular smooth muscle reactivity were assessed by serotonin and sodium nitroprusside, respectively. Myocardial damage was assessed by coronary effluent creatine phosphokinase and by morphologic studies. Papillary muscles were then excised and contractile characteristics evaluated at varying extracellular calcium concentration prior to and after endocardial endothelial removal with Triton X100. All three interventions eliminated all coronary vascular response to serotonin but did not modify response to nitroprusside. Creatine phosphokinase values rose only in hearts with ischemia-reperfusion, and only minor morphologic changes occurred, mostly in hearts with ischemia-reperfusion. Papillary muscles from hearts with intracoronary Triton X100 injection had lower contractile indices compared with normal controls (total tension 4.0 vs. 4.6 g/mm2, p < 0.01) and an abbreviation of contraction duration. Increasing extracellular calcium concentration from to 0.7 to 3.25 mM eliminated these differences. Similar but more marked decreases in contractile indices and twitch duration were noted in the two ischemia-reperfusion groups, but consistent with some myocardial damage being present, increasing extracellular calcium concentration to 3.25 or 7 mM did not fully eliminate these differences. In both ischemia-reperfusion groups and the intracoronary Triton X100 group, the relative increase in total tension with increasing extracellular calcium concentrations was similar (35 to 38%) and greater than that of the control group (25%), consistent with dysfunction of vascular endothelium contributing to myocardial dysfunction in the three intervention groups. Endocardial endothelial removal had a similar effect in all four groups, suggesting that dysfunction of endocardial endothelium does not play a role in this model. We conclude that vascular but not endocardial endothelial dysfunction contributes to the myocardial dysfunction that occurs during ischemia-reperfusion injury.

Vascular endothelial dysfunction contributes to myocardial depression in ischemia-reperfusion in the rat

Endocardial and vascular myocardial capillary endothelium has been shown to modulate the contractile characteristics of myocardium by altering myofibrillar affinity for calcium. Although the release of endothelial-derived substances that modify myocardial contractility has been shown to be altered in certain physiologic and pathologic situations, until now no study has evaluated whether the direct modulatory effects of endothelium on its subjacent myocardium were altered in pathologic situations and contributed to loss of contractile function. This study was designed to evaluate whether the direct contractile modulatory effects of endocardial and (or) vascular endothelium were altered and whether these alterations contributed to contractile dysfunction in a model of ischemia-reperfusion. Sixty-two perfused rat hearts as Langendorff preparations were randomized to no intervention, intracoronary Triton X100 injection (to render vascular endothelium dysfunctional), ischemia (30 min) - reperfusion (20 min), and ischemia-reperfusion followed by intracoronary Triton X100 injection. Coronary endothelial-dependent vascular reactivity and vascular smooth muscle reactivity were assessed by serotonin and sodium nitroprusside, respectively. Myocardial damage was assessed by coronary effluent creatine phosphokinase and by morphologic studies. Papillary muscles were then excised and contractile characteristics evaluated at varying extracellular calcium concentration prior to and after endocardial endothelial removal with Triton X100. All three interventions eliminated all coronary vascular response to serotonin but did not modify response to nitroprusside. Creatine phosphokinase values rose only in hearts with ischemia-reperfusion, and only minor morphologic changes occurred, mostly in hearts with ischemia-reperfusion. Papillary muscles from hearts with intracoronary Triton X100 injection had lower contractile indices compared with normal controls (total tension 4.0 vs. 4.6 g/mm2, p << 0.01) and an abbreviation of contraction duration. Increasing extracellular calcium concentration from 0.7 to 3.25 mM eliminated these differences. Similar but more marked decreases in contractile indices and twitch duration were noted in the two ischemia-reperfusion groups, but consistent with some myocardial damage being present, increasing extracellular calcium concentration to 3.25 or 7 mM did not fully eliminate these differences. In both ischemia-reperfusion groups and the intracoronary Triton X100 group, the relative increase in total tension with increasing extracellular calcium concentrations was similar (35 to 38%) and greater than that of the control group (25%), consistent with dysfunction of vascular endothelium contributing to myocardial dysfunction in the three intervention groups. Endocardial endothelial removal had a similar effect in all four groups, suggesting that dysfunction of endocardial endothelium does not play a role in this model. We conclude that vascular but not endocardial endothelial dysfunction contributes to the myocardial dysfunction that occurs during ischemia-reperfusion injury.Key words: endocardial endothelium, vascular endothelium, ischemia reperfusion, myocardial contractility.

The impact of dengue haemorrhagic fever on liver function

The impact of dengue haemorrhagic fever (DHF) on liver function was studied by measuring serum transaminase levels on 45 patients with DHF confirmed by virus isolation and serodiagnosis in 1995. Abnormal levels of AST and ALT were observed in 97.7 and 37.3% of the patients, respectively. The fact that the level of AST was higher than that of ALT and that the elevation of transaminases was mild to moderate in most cases (< 5-fold greater than the normal upper limit for AST and ALT) showed that liver involvement was also mild to moderate in most cases of DHF. The results of transaminases did not differ significantly between cases with and without hepatitis B or hepatitis C virus infection, nor between primary and secondary cases of infection, but a significantly higher elevation of AST and ALT was observed in DHF patients with gastrointestinal haemorrhage. Two patients with dengue encephalopathy (in 1992) and one patient with dengue encephalopathy who died of massive gastrointestinal haemorrhage (in 1995) had unusually high transaminase levels as a sign of acute liver failure. It is concluded that DHF may cause mild to moderate liver dysfunction in most cases; only some patients may suffer from acute liver failure leading to encephalopathy and death.

Short courses of ofloxacin for the treatment of enteric fever

Typhoid fever continues to be a major public health problem in tropical countries, exacerbated in recent years by the spread of multi-drug resistant strains of Salmonella typhi. Short treatment courses of fluoroquinolones are effective, and have the advantage of reduced cost and increased compliance, but the optimal length of treatment is unknown. In an open, randomized comparison, 107 adults with uncomplicated enteric fever (95 of whom had positive blood cultures for S. typhi and 5 for S. paratyphi) were treated with oral ofloxacin, 15 mg/kg/d for 2 d or 10 mg/kg/d for 3 d. Mean fever clearance times were the same in the 2 treatment groups (97 h). There were 7 treatment failures, one in the 2 d group and 6 in the 3 d group (P = 0.07). Three of the 5 patients infected with nalidixic acid resistant strains of S. typhi had treatment failures, compared with 4 of 90 with nalidixic acid sensitive isolates (P < 0.0001; relative risk 13.5, 95% confidence interval 4.1-43%). Treatment with ofloxacin for 2 or 3 d is equally effective in adults with uncomplicated enteric fever caused by nalidixic acid sensitive strains of S. typhi. The epidemiology and management of nalidixic acid resistent typhoid needs further investigation.

Two major strains of type 1 wild poliovirus circulating in Indochina

Two hundred ninety-four isolates from 329 patients with acute flaccid paralysis in Cambodia and Vietnam during 1992-1995 were identified as type 1 wild polioviruses. Among these isolates, 85 were selected as geographic representatives and were examined by determining the nucleotide sequences of their genome in the VP1 region. The phylogenic analysis revealed that all of the isolates examined were classified into groups A and B. Isolates belonging to group A had been found only in northern Vietnam until 1993 but not in 1994 and 1995. Group B isolates were located in both northern and southern Vietnam and Cambodia. In 1994 and 1995, however, only group B isolates were found in the Mekong Delta area in southern Vietnam and Cambodia. Isolates of groups A and B were genetically different from strains previously isolated in other Asian countries. One of the two indigenous wild polioviruses still remains to be eliminated in this area.

[Congenital dilatation of the common bile duct in children. Study of a series of 52 cases]

OBJECTIVE

The aim of this study was to evaluate results at long-term follow-up of patients suffering from congenital dilatation of the bile duct according to the type of operative procedure.

METHOD

A retrospective study of 52 patients who were operated on during a 25-year period was carried out. Of 52 patients, 43 (83%) were female and 9 (17%) were male, with a ratio of 4.8/1. In six cases, the diagnosis was made antenatally by ultrasonography. Transhepatic cholangiography showed an extrahepatic dilatation in 25 cases (48%) and a combined extra and intrahepatic dilatation in 27 cases (52%). A common bilio-pancreatic channel was found in 25 patients. Mean age at the time of operation was 4.2 years. Operative procedures included: cyst excision and hepaticojejunostomy in 47 cases, cystojejunostomy or cystoduodenostomy in 4 cases and cystostomy in one case. There were two postoperative deaths.

RESULTS

Long-term follow-up was established in 43 of 50 survivors (80%). One patient was reoperated because of portal hypertension. Cholangitis developed in 11 patients: 2/2 patients who had undergone in internal drainage and 9/41 patients who had undergone a cyst excision with hepaticojejunostomy. In patients with cyst excision, cholangitis developed twice as frequently in those with associated intrahepatic dilatation. Two of 11 children with recurrent cholangitis died following sepsis, and three others were reoperated because of intrahepatic bile duct stones, one of these 15 years later.

CONCLUSION

A total excision of the extrahepatic biliary tract, followed by hepaticojejunostomy is considered as a treatment of choice. The site of the biliary anastomosis should be adapted to the type of dilatation of intrahepatic bile duct in the case of a combined extra and intrahepatic dilatation.

Lipid composition and structure of commercial parenteral emulsions

In order to study the influence of the phospholipid/triacylglycerol (PL/TG) ratio of parenteral emulsions on the distribution and the physico-chemical properties of their fat particles, commercial 10, 20 or 30% fat formulas were fractionated by centrifugation into an upper lipid cake (resuspended in aqueous glycerol) and a subnatant or mesophase, from which a PL-rich subfraction (d = 1.010-1.030 g/l) was purified by density gradient ultracentrifugation. Chemical and 31P-NMR analyses of these fractions indicated that at least two types of fat particles coexist in parenteral emulsions: (i) TG-rich particles (mean diameter: 330, 400, 470 nm in the 10, 20, 30% emulsion) which contain practically all the TG and esterified phytosterols of native emulsions, but only a fraction of their PL, unesterified cholesterol and phytosterols, and other minor lipids; (ii) PL-bilayer particles or liposomes (mean diameter: 80-100 nm) which are constituted with the remaining PL and relatively very small amounts of TG and other lipids. The higher the oil content of the emulsion, the lower the amount of these PL-rich particles, which represent the major particle population of the mesophase. Indeed, minute amounts of TG-rich particles (probably the smallest ones) are also present in the mesophase, even in the PL-rich subfraction which contains the bulk of liposomal PL. Since the PL-rich particles of the infused emulsion generate lipoprotein X-like particles, only the large TG-rich particles can be considered as true chylomicron counterparts.

Synthesis and photodynamic activities of silicon 2,3-naphthalocyanine derivatives

Bis(tert-butyldimethylsiloxy)- (7), bis(dimethylthexylsiloxy)- (8), bis(tri-n-hexylsiloxy)- (9), and bis(dimethyloctadecylsiloxy)silicon 2,3-naphthalocyanines (10) were prepared via substitution of the bis(hydroxy) precursor with the corresponding chlorosilane ligands and characterized by spectroscopic and combustion analyses. They show strong absorption around 780 nm where tissues exhibit optimal transparency. Compounds 7-10 are capable of producing singlet oxygen. They are relatively photostable although less stable than the analogous phthalocyanine, i.e., the bis-(dimethylthexylsiloxy)silicon phthalocyanine (12). They were evaluated as potential photosensitizers for the photodynamic therapy (PDT) of cancer in vitro against V-79 cells and in vivo against the EMT-6 tumor in Balb/c mice. In vitro all four dyes showed limited phototoxicity combined with substantial dark toxicity. Surprisingly, in vivo (i.v., 0.1 mumol/kg, 24 h prior to the photoirradiation of the tumor with 780-nm light, 190 mW/cm2, 400 J/cm2) all dyes induced tumor regression in at least 50% of mice whereas compound 8 gave a complete tumor response in 80% of mice without apparent systemic toxicity at doses as high as 10 mumol/kg. At 24 h postinjection, compound 8 showed a favorable tumor to muscle ratio of 7, assuring minimal damage to the healthy tissue surrounding the tumor during PDT. Our data confirm the potential of silicon naphthalocyanines as far-red-shifted photosensitizers for the PDT of cancer and indicate the importance of the selection of the two axial silicon ligands for optimal photodynamic efficacy.

[The clinical efficacy of and tolerance for lariam (mefloquine) in tropical malaria in the south of the Socialist Republic of Vietnam]

The study was performed in the area of distribution of tropical malaria resistant to 4-aminoquinolines (Vietnam) on 30 patients receiving lariam (mefloquine). The results were compared to the standard therapy with quinine and fansidar. They indicate a high efficacy of and a good tolerance to the drug tested. The use of lariam leads to a more rapid (as compared to the standard treatment) elimination of parasitemia and complete eradication of the disease relapses. The findings make it possible to recommend lariam for the prevention and treatment of tropical malaria.

Quantitative estimation of quaternary ammonium neuromuscular blocking agents in serum by direct insertion probe chemical ionization mass spectrometry

A new method based on selected ion monitoring chemical ionization mass spectrometry was developed to measure the quaternary ammonium neuromuscular blocking agents, pancuronium and vecuronium, in serum. An ion-pair extraction procedure is utilized to separate the compounds of interest from biological fluids. The intensities of the ion currents produced by the bisamines formed from the drugs and the corresponding deuterated internal standards through thermolytic dequaternization are monitored. The assay shows good linearity over the range of 1-500 ng/ml. This assay has been utilized in a variety of clinical pharmacokinetic studies involving surgical pediatric, geriatric and obstetric patients requiring anesthesia.