[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.

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.

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.

Determination of chlorpromazine and its major metabolites by gas chromatography/mass spectrometry: application to biological fluids

A method for the quantitative determination of chlorpromazine and five of its major metabolites in a single sample of biological fluid in the ng/ml range has been developed utilizing gas chromatography/mass spectrometry with selected ion recording. The assay is highly specific and quantification is accomplished by an inverse stable isotope dilution technique, using deuterium-labeled variants of the compounds as internal standards. In this way the concentrations of chlorpromazine and five of its major metabolites (the sulfoxide, the N-oxide, the monodemethylated, the didemethylated, and the 7-hydroxylated compounds) can be determined in biological fluids. Levels in humans have been measured both in plasma and in red blood cells and are compared to those found in related in vitro studies.

Simultaneous analysis of imipramine and its metabolite desipramine in biological fluids

A method for the simultaneous quantitation of imipramine and its N-demethylated metabolite desipramine at the nanogram level in a single gas chromatograph peak is presented, utilizing gas chromatography-mass spectrometry with selected ion recording. The assay is specific and quantitation is achieved using [2H4]imipramine as the internal standard. The method involves the in situ methylation of desipramine with [2H2]formaldehyde and sodium borohydride to give [2H2]imipramine. Quantitation is then achieved by selected ion recording at m/z 280, 282 and 284, whence the ratio of the ion currents at 280/284 and at 282/284 gives the quantities of imipramine and desipramine respectively.