Local hemodynamic disturbance accelerates early thrombosis of small-caliber expanded polytetrafluoroethylene grafts

OBJECTIVE

Small-caliber expanded polytetrafluoroethylene (ePTFE) grafts cannot be used widely in the clinical situation because of early thrombosis and occlusion. This unsolved and under-recognized problem warrants further investigation.

METHODS

Grafts of uncoated ePTFE (n = 6) and anti-CD34-coated ePTFE (n = 6) were implanted unilaterally into the carotid artery in 12 domestic pigs. Ultrasonography was used to test the proximal and distal anastomotic stoma morphology, diameters and blood velocities. A thrombosis instrument was used to examine the blood coagulation state. After seven days, the pigs were sacrificed and the implanted grafts were excised for general and histological analysis. Computational fluid dynamics was used to investigate the blood flow fields of the implanted grafts and to calculate parameters that might be indicative of thrombosis.

RESULTS

Thrombosis was detected in 10 of 12 (83.3%) implanted ePTFE grafts, 5 in uncoated grafts and 5 in anti-CD34-coated grafts. Endothelial cell coverage was observed in both uncoated and anti-CD34-coated grafts. No obvious abnormalities in anastomotic stoma or blood coagulation state were observed. Computer-based local hemodynamic simulation showed the low flexibility of synthetic ePTFE grafts caused obvious coarctation. Local wall pressure, velocity and wall shear stress were much higher than in the contralateral normal vessel.

CONCLUSIONS

The patency of small-caliber ePTFE grafts for clinical use is impaired by early thrombosis due to mixed causes. Local hemodynamic disturbance was the most powerful predictor of early thrombosis. Decreasing local hemodynamic disturbance, improving the quality of anastomotic stoma, selecting reasonable anticoagulation strategies and promoting rapid endothelialization may increase the long-term patency of small-caliber vascular grafts.

Segregation of secondary metabolite biosynthesis in hybrids of Fusarium fujikuroi and Fusarium proliferatum

Fusarium fujikuroi and Fusarium proliferatum are two phylogenetically closely related species of the Gibberella fujikuroi species complex (GFC). In some cases, strains of these species can cross and produce a few ascospores. In this study, we analyzed 26 single ascospore isolates of an interspecific cross between F. fujikuroi C1995 and F. proliferatum D4854 for their ability to produce four secondary metabolites: gibberellins (GAs), the mycotoxins fusarin C and fumonisin B(1), and a family of red polyketides, the fusarubins. Both parental strains contain the biosynthetic genes for all four metabolites, but differ in their ability to produce these metabolites under certain conditions. F. fujikuroi C1995 produces GAs and fusarins, while F. proliferatum D4854 produces fumonisins and fusarubins. The segregation amongst the progeny of these traits is not the expected 1:1 Mendelian ratio. Only eight, six, three and three progeny, respectively, produce GAs, fusarins, fumonisin B(1) and fusarubins in amounts similar to those synthesized by the producing parental strain. Beside the eight highly GA(3)-producing progeny, some of the progeny produce small amounts of GAs, predominantly GA(1), although these strains contain the GA gene cluster of the non-GA-producing F. proliferatum parental strain. Some progeny had recombinant secondary metabolite profiles under the conditions examined indicating that interspecific crosses can yield secondary metabolite production profiles that are atypical of the parent species.

Bioethanol production from hydrolysates of inulin and the tuber meal of Jerusalem artichoke by Saccharomyces sp. W0

It has been confirmed that Saccharomyces sp. W0 can produce high concentration of ethanol. However, this yeast strain cannot secrete inulinase. Therefore, in this study, inulin was hydrolyzed into reducing sugar by the recombinant inulinase produced by Pichia pastoris X-33/pPICZaA-INU1. It was found that 38.2U of the recombinant inulinase per gram of inulin was suitable for the inulin hydrolysis and ethanol production by Saccharomyces sp. W0 and the fermentation period was 120 h. At the end of the fermentation, over 14.6 ml of ethanol per 100ml of the fermented medium was produced, the ethanol productivity was over 0.384 g of ethanol/g of inulin and over 98.8% of total sugar was utilized. When the Saccharomyces sp. W0 was grown in the mixture of 4.0% hydrolysate of soybean meal and 20.0% of the hydrolysate of inulin for 120 h, over 14.9 ml of ethanol per 100ml of the fermented medium was yielded, the ethanol productivity was over 0.393 g of ethanol/g of inulin and 98.9% of total sugar was used by the yeast strain. When Saccharomyces sp. W0 carrying the same inulinase gene was grown in the medium containing 50 g of the tuber meal of Jerusalem artichoke per 100ml for 144 h, over 12.1+/-0.35%ml of ethanol per 100ml of the fermented medium was yielded, the ethanol productivity was 0.319+/-0.9 g of ethanol/g of sugar and 3.7% (w/v) of total sugar and 0.5% (w/v) of reducing sugar were left in the fermented media.

Mesenchymal stroma cells improve hyperglycemia and insulin deficiency in the diabetic porcine pancreatic microenvironment

BACKGROUND

Stem cell differentiation is controlled by extracellular cues from the environment and by intrinsic genetic programs within the stem cell. The present study aimed to explore whether mesenchymal stromal cells (MSC) could improve hyperglycemia and insulin production in the diabetic microenvironment.

METHODS

We transplanted male porcine bone marrow-derived EGFP-expressing MSC directly into female diabetic porcine pancreas by multi-point injection. Enzyme-linked immunosorbent assay (ELISA) and fluorescent immunohistochemistry were used to analyze recipients' sera and pancreas tissues for assessment of the therapeutic effect.

RESULTS

Blood glucose levels decreased gradually in MSC-treated recipients from 15 days after the transplantation compared with untreated diabetic controls (15.94+/-0.31 mmol/L versus 16.66+/-0.11 mmol/L; P=0.01). Blood insulin increased and glucagons decreased notably in recipients from 2 weeks post-transplantation compared with untreated diabetic controls (0.049+/-0.004 microg/L versus 0.037+/-0.02 microg/L and 392.9+/-20.3 ng/L versus 433.1+/-27.6 ng/L). Hematoxylin and eosin (HE)-stained sections demonstrated that the number of islets from each section was markedly increased in recipients compared with that of diabetic controls (10.9+/-2.2 versus 4.6+/-1.4; P<0.05) and similar to that of normal controls (10.9+/-2.2 versus 12.6+/-2.6; P>0.05). The newly formed islets were smaller than normal islets (47.2+/-19.6 microm versus 119.6+/-27.7 microm; P<0.05). Analysis of pancreatic sections for EGFP in recipients indicated that the transplanted MSC survived within the pancreas. Insulin immunoreactivity of pancreatic islets showed that the newly formed islets expressed insulin.

DISCUSSION

MSC could improve diabetes upon pancreatic microenvironment without obvious immune rejections. This has theoretical and clinical applications.

Nonlinear pressure shifts of alkali-metal atoms in inert gases

Precise measurements show that the microwave resonance frequencies of ground-state Rb or Cs atoms have a nonlinear dependence on the pressure of the buffer gases Ar and Kr. No nonlinearities were observed in the gases He or N(2). These observations strongly suggest that the nonlinearities are due to the van der Waals molecules that form in Ar and Kr, but not in He or N(2). The nonlinear part of the shifts is largest in the pressure range of a few tens of torr, similar to the operating pressures of gas-cell atomic clocks. The observed shifts are very well described by a simple function, parametrized by the effective three-body formation rate of molecules and by the effective product of the collisionally limited lifetime times the shift of the hyperfine coupling coefficient in the molecule.

Mesenchymal stem cells contribute to insulin-producing cells upon microenvironmental manipulation in vitro

BACKGROUND

Extracellular microenvironment and intrinsic genetic programs determine the fate of stem cells. We observed whether mesenchymal stem cells (MSCs) contributed to insulin-producing cells in a manipulated microenvironment.

METHODS

We delivered pancreatic pieces into Niobium-Coated Dynamatrix to construct a simulated pancreatic microenvironment, upon which soluble cytokine exchange and direct cell-cell contact between MSCs and pancreatic cells could occur. Bone marrow-derived MSCs were cultured upon the microenvironment. Differentiated isletlike cells were observed under an inverted microscope. Insulin in supernates was measurement by enzyme-linked immunosorbent assay. Insulin and c-peptide expression were verified by fluorescent immunocytochemistry and fluorescence in situ hybridization. Apoptosis of isletlike masses in high-glucose DMEM was detected by FACS.

RESULTS

After 3 to 4 weeks in culture, typical isletlike masses were observed. Insulin secreted by differentiated cells (414.47+/-30.30 mIU/L) was much greater than that of undifferentiated cells (4.89+/-1.01 mIU/L; P<.05). Insulin and c-peptide expression were positive both in protein and mRNA levels. The transdifferentiated isletlike mass did not undergo apoptosis after another 3 weeks of culture in high-glucose DMEM.

CONCLUSION

This simulated injury microenvironment without induction guided MSCs to functional isletlike cells hopefully to replace beta cells.

Extracellular hmgb1 functions as an innate immune-mediator implicated in murine cardiac allograft acute rejection

Hmgb1, an evolutionarily conserved chromosomal protein, was recently re-discovered to be an innate immune-mediator contributing to both innate and adaptive immune responses. Here, we show a pivotal role for Hmgb1 in acute allograft rejection in a murine cardiac transplantation model. Extracellular Hmgb1 was found to be a potent stimulator for adaptive immune responses. Hmgb1 can be either passively released from damaged cells after organ harvest and ischemia/reperfusion insults, or actively secreted by allograft infiltrated immune cells. After transplantation, allografts show a significant temporal up-regulation of Hmgb1 expression accompanied by inflammatory infiltration, a consequence of graft destruction. These data suggest the involvement of Hmgb1 in acute allograft rejection. In line with these observations, treatment of recipients with rA-box, a specific blockade for endogenous Hmgb1, significantly prolonged cardiac allograft survival as compared to those recipients treated with either rGST or control vehicle. The enhanced graft survival is associated with reduced allograft expression of TNFalpha, IFNgamma and Hmgb1 and impaired Th1 immune response.

The clinical study and HLA genotyping of 112 familial myasthenia gravis patients

One hundred and twelve cases of familial myasthenia gravis (MG) from 44 families selected from 2100 patients with MG diagnosed since 1983 in the Department of Neurology were studied. The clinical pictures and immunological features of the patients showed a great resemblance to those of sporadic cases. The pedigree analysis disclosed that the hereditary patterns of familial patients were basically Mendellian autosomal inheritance. Many predisposing factors such as fever, infection, use of aminoglycoside or vaccines, played an important role in presenting the phenotype of subclinical cases. The HLA genotyping suggested that the complement polymorphism C4A * 4, the complotype S42, and the genes 0901 and 1301 of DRB1 allele, were related to the pathogenesis of MG. It was concluded that the phenotype of MG may be the result of interaction between hereditary defects and environmental factors.

[Preliminary study on application of blastocyst culture and day 5 transfer in patients with low oocyte number]

OBJECTIVE

To evaluate whether blastocyst culture and transfer in patients with low oocyte number can effectively improve the outcome of in vitro fertilization-embryo transfer treatment.

METHODS

Retrospectively analyze 59 couples received conventional in vitro fertilization and embryo transfer (IVF-ET) treatment in our center from January to February 2000. Twenty-one couples had blastocyst culture and day 5 embryo transfer and another 38 couples had day 2 embryo transfer as the control. Their clinical and laboratory results were compared between these two groups.

RESULTS

In day 5 group the mean oocytes retrieved were (6.6 +/- 2.8), the clinical pregnancy rates (PRs) was 43% and the life delivery rate was 38%; while in day 2 group the results were (6.9 +/- 3.7), 37% and 29% respectively. There was no significant difference between two groups. No high-order multiple birth occurred in day 5 group, but in day 2 group there were two cases: one with triplets and another with pentadriplet who had the embryos reduction.

CONCLUSIONS

These results demonstrate that nonselective blastocyst culture and transfer in patients with low oocyte number seems not effectively to improve the PRs and the delivery rate, but may decrease the occurrence of multiple birth without affecting the final pregnancy results when compared with conventional day 2 transfer.

The mechanism of tryptophan induction of tryptophanase operon expression: tryptophan inhibits release factor-mediated cleavage of TnaC-peptidyl-tRNA(Pro)

Expression of the tryptophanase (tna) operon of Escherichia coli is regulated by catabolite repression and tryptophan-induced transcription antitermination. In a previous study, we reproduced the regulatory features of this operon observed in vivo by using an in vitro S-30 system. We also found that, under inducing conditions, the leader peptidyl-tRNA (TnaC-peptidyl-tRNA(Pro)) is not cleaved; it accumulates in the S-30 reaction mixture. In this paper, we examine the requirements for TnaC-peptidyl-tRNA(Pro) accumulation and cleavage, in vitro. We show that this peptidyl-tRNA remains bound to the translating ribosome. Removal of free tryptophan and addition of release factor 1 or 2 leads to hydrolysis of TnaC-peptidyl-tRNA(Pro) and release of TnaC from the ribosome-mRNA complex. Release factor-mediated cleavage is prevented by the addition of tryptophan. TnaC of the ribosome-bound TnaC-peptidyl-tRNA(Pro) was transferable to puromycin. This transfer was also blocked by tryptophan. Tests with various tryptophan analogs as substitutes for tryptophan revealed the existence of strict structural requirements for tryptophan action. Our findings demonstrate that the addition of tryptophan to ribosomes bearing nascent TnaC-peptidyl-tRNA(Pro) inhibits both TnaC peptidyl-tRNA(Pro) hydrolysis and TnaC peptidyl transfer. The associated translating ribosome therefore remains attached to the leader transcript where it blocks Rho factor binding and subsequent transcription termination.

Characterization of the D-glucuronyl C5-epimerase involved in the biosynthesis of heparin and heparan sulfate

The murine gene for the glucuronyl C5-epimerase involved in heparan sulfate biosynthesis was cloned, using a previously isolated bovine lung cDNA fragment (Li, J.-P., Hagner-McWhirter, A., Kjellén, L., Palgi, J., Jalkanen, M., and Lindahl, U. (1997) J. Biol. Chem. 272, 28158-28163) as probe. The approximately 11-kilobase pair mouse gene contains 3 exons from the first ATG to stop codon and is localized to chromosome 9. Southern analysis of the genomic DNA and chromosome mapping suggested the occurrence of a single epimerase gene. Based on the genomic sequence, a mouse liver cDNA was isolated that encodes a 618-amino acid residue protein, thus extending by 174 N-terminal residues the sequence deduced from the (incomplete) bovine cDNA. Comparison of murine, bovine, and human epimerase cDNA structures indicated 96-99% identity at the amino acid level. A cDNA identical to the mouse liver species was demonstrated in mouse mast cells committed to heparin biosynthesis. These findings suggest that the iduronic acid residues in heparin and heparan sulfate, despite different structural contexts, are generated by the same C5-epimerase enzyme. The catalytic activity of the recombinant full-length mouse liver epimerase, expressed in insect cells, was found to be >2 orders of magnitude higher than that of the previously cloned, smaller bovine recombinant protein. The approximately 52-kDa, similarly highly active, enzyme originally purified from bovine liver (Campbell, P., Hannesson, H. H., Sandbäck, D., Rodén, L., Lindahl, U., and Li, J.-P. (1994) J. Biol. Chem. 269, 26953-26958) was found to be associated with an approximately 22-kDa peptide generated by a single proteolytic cleavage of the full-sized protein.

Determination of volatile components in peptic powder by gas chromatography-mass spectrometry and chemometric resolution

Gas chromatography-mass spectrometry (GC-MS) coupled with chemometric resolution upon two-dimensional data was proposed as a method for the analysis of volatile components in a traditional Chinese medicinal preparation peptic powder which contains Rhizoma Atractylodis, Pericarpium Citri Reticulatae, Cortex Magnoliae Officinalis and Radix Glycyrrhizae. Ninety-three components were separated and 65 of them were qualitatively and quantitatively analyzed which represented about 90.28% of the total content. With the help of chemometric resolution, the data were resolved into a pure chromatogram and a mass spectrum of each chemical component. The accuracy of qualitative and quantitative results was greatly improved by using the two-dimensional comprehensive information of chromatograms and mass spectra. The example showed that chemometric resolution could greatly enhance separation ability. This makes it possible to analyze complicated practical systems like traditional Chinese medicinal preparations with the help of coupled instruments and chemometric resolution methods.

The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

Reproducing tna operon regulation in vitro in an S-30 system. Tryptophan induction inhibits cleavage of TnaC peptidyl-tRNA

Expression of the tryptophanase (tna) operon of Escherichia coli is regulated by catabolite repression and tryptophan-induced transcription antitermination. Catabolite repression regulates transcription initiation, whereas excess tryptophan induces antitermination at Rho factor-dependent termination sites in the leader region of the operon. Synthesis of the leader peptide, TnaC, is essential for antitermination. BoxA and rut sites in the immediate vicinity of the tnaC stop codon are required for termination. In this paper we use an in vitro S-30 cell-free system to analyze the features of tna operon regulation. We show that transcription initiation is cyclic AMP (cAMP)-dependent and is not influenced by tryptophan. Continuation of transcription beyond the leader region requires the presence of inducing levels of tryptophan and synthesis of the TnaC leader peptide. Using a tnaA'-'trpE fusion, we demonstrate that induction results in a 15-20-fold increase in synthesis of the tryptophan-free TnaA-TrpE fusion protein. Replacing Trp codon 12 of tnaC by an Arg codon, or changing the tnaC start codon to a stop codon, eliminates induction. Addition of bicyclomycin, a specific inhibitor of Rho factor action, substantially increases basal level expression. Analyses of tna mRNA synthesis in vitro demonstrate that, in the absence of inducer transcription is terminated and the terminated transcripts are degraded. In the presence of inducer, antitermination increases the synthesis of the read-through transcript. TnaC synthesis is observed in the cell-free system. However, in the presence of tryptophan, a peptidyl-tRNA also appears, TnaC-tRNA(Pro). Our findings suggest that inducer acts by preventing cleavage of TnaC peptidyl-tRNA. The ribosome associated with this newly synthesized peptidyl-tRNA presumably stalls at the tnaC stop codon, blocking Rho's access to the BoxA and rut sites, thereby preventing termination. 1-Methyltryptophan also is an effective inducer in vitro. This tryptophan analog is not incorporated into TnaC.

Gas chromatography-mass spectrometry and chemometric resolution applied to the determination of essential oils in Cortex cinnamomi

In this paper, a novel procedure for qualitative and quantitative analysis of the two-dimensional data obtained from GC-MS is investigated to determine chemical components of essential oils in Cortex Cinnamomi from four different producing areas. A new method named iterative optimization procedure (IOP) specially used to resolve embedded peaks is also developed. With the help of IOP and other chemometric techniques, such as heuristic evolving latent projections, evolving factor analysis, sub-window factor analysis and orthogonal projection resolution, and etc., the detection of the purity of chromatographic peaks can be first addressed, and then the overlapping peaks are resolved into the pure chromatogram and mass spectrum of each component. The similarity searches in the MS database are finally conducted to qualitatively determine the chemical components. The results obtained showed that the accuracy of qualitative and quantitative analysis could be greatly enhanced by chemometric resolution methods. The chemometric resolution techniques upon the two-dimensional data can be quite promising tools for the analysis of the complex samples like traditional Chinese medicine.

Establishment of in vitro cellular model predicting histocompatibility in allograft

A novel in vitro cellular model producting recipient-donor histocompatibility in allograft was developed to select the donor validity. Fifteen couples of blood samples of donor and recipient in human BMT were examined using the model, and skin allograft in mice was performed to test the model. The results showed that the less the differences of histocompatibility evaluated by the model were, the later GVHR in human BMT occurred and the longer the survival time of skin allografts in mice. It was suggested that the model could be used to predict correctly histocompatibility between donor and recipient.

Wireless endoscopy

BACKGROUND

Miniaturization of electronic components may allow the construction of new types of endoscopes that no longer require external wires, cables, or optical fibers. Our aim was to assess the feasibility of wireless endoscopy and to construct experimental prototypes using miniature charge-coupled device cameras, light sources, microwave transmitters, and batteries.

METHODS

Feasibility, dimensions of miniature components, and power requirements were assessed. Prototypes were constructed and tested using cameras, transmitters, and halogen lamps powered by small batteries; 10.6 and 0.187 GHz transmitters were used to transmit the video signal.

RESULTS

Moving television images were transmitted through models, post-mortem and live porcine stomachs, to the external receiver. Transmission of images through the abdomen was tested by placing the device in a microwave-impermeable box behind a volunteer's back and the receiver in front of his abdomen. In other experiments the endoscope was used inside the human mouth. The device was placed surgically in the stomachs of 150 kg pigs in vivo and good-quality color television image reception was achieved.

CONCLUSIONS

These experiments demonstrate the feasibility of constructing a new type of endoscope that can transmit moving color television images from the GI tract without requiring fiberoptic or electrical cables.

Inhalation of nebulized nitroglycerin in dogs with experimental pulmonary hypertension induced by U46619

BACKGROUND

Pulmonary hypertension (PH) causes mortality in some congenital and acquired heart and lung diseases. However, inhalation of NO gas requires complicated and expensive instruments and elaborate preparations to avoid toxic gas administration. We tested the effectiveness and safety of inhaled nebulized nitroglycerin (Neb-NTG) in dogs with experimental PH.

METHODS

Experimental PH was induced by continuous infusion of a thromboxane analog (U46619). The U46619 infusion rate was adjusted to maintain a systolic pulmonary artery pressure (PAP) at 40 mmHg in 10 anesthetized and mechanically ventilated dogs. Then, 20 micrograms/kg of NTG liquid nebulized by compressed air was inhaled.

RESULTS

After infusion of U46619, the systolic, diastolic and mean PAP increased by 119%, 228% and 169%, respectively, and the systolic, diastolic and mean systemic arterial pressures (SAP) increased by 19%, 29% and 23%, respectively. The systolic pulmonary to systemic pressure ratio (Pp/Ps) and mean Pp/Ps increased by 83% and 113%, respectively, and the pulmonary vascular resistance (PVR), systemic vascular resistance (SVR) and pulmonary to systemic resistance ratio (Rp/Rs) increased by 341%, 100% and 145%, respectively. After inhalation of Neb-NTG in dogs with experimental PH, systolic, diastolic and mean PAP and PVR decreased by 25 +/- 4, 26 +/- 11, 25 +/- 9 and 31 +/- 21%, respectively. There were no significant changes in systolic, diastolic and mean SAP, SVR, cardiac output and plasma methemoglobin concentrations. The systolic and mean Pp/Ps decreased by 18 +/- 7 and 20 +/- 7%, respectively. The Rp/Rs decreased by 25 +/- 13%.

CONCLUSIONS

The results of this study demonstrate that Neb-NTG is an effective and selective pulmonary vasodilator and may offer a new therapeutic option for PH.

The genome sequence of Drosophila melanogaster

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

Comparative genomics of the eukaryotes

A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease.

HLA-DRB1 gene polymorphism in patients with dilated cardiomyopathy

To probe into the genetic background and immunopathogenesis of dilated cardiomyopathy (DCM), HLA-DRB1 gene polymorphism in 68 patients with DCM and 175 normal control subjects were analyzed by using the polymerase chain reaction/sequence specific primer (PCR/SSP) techniques. It was found that the frequencies of HLA-DRB1* 15 and HLA-DRB1* 03 alleles were significantly lower in DCM patients than those in normal controls (14.71% vs 29.71% and 4.41% vs 15.43%, respectively), the relative risks (RR) in the DCM patients being 0.41 and 0.25, respectively, all P < 0.05. However, the frequencies of HLA-DRB1* 11 and HLA-DRB1* 12 alleles were significantly higher in the DCM patients than in controls (29.4% vs 12.00% and 36.76% vs 12.57%, respectively) with the RR in the DCM patients being 3.06 and 4.04, respectively, all P < 0.01. These findings further demonstrated that immunogenetics might play a predominant pathogenetic role in partial DCM patients.

[An investigation of the polymorphism of HLA class II alleles in the Han population in Hubei Province of China]

OBJECTIVE

To investigate the polymorphism of HLA class II alleles in the Han population in Hubei province.

METHODS

The alleles of DRB1*(n=168), DQB1*(n=160) and DPB1*(n=93) were typed by using the polymerase chain reaction/sequence specific primer(PCR/SSP) and polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) techniques.

RESULTS

39 HLA-DRB1, 15 DQB1 and 17 DPB1 alleles were found. Alleles with higher frequencies are DRB1*0901 (GF=14%), *1501(GF=11.3%), *0301(GF=7.1%), *0803(GF=4.8%); DQB1*0301(GF=18.8%), *0303(GF=18.4%), *0201(GF=10%), *0302(GF=8.4%); DPB1*0501(GF=31.2%), *0401(GF=15.1%), *0201(GF=14%), *0402(GF=11.8%), respectively. As compared with Caucasians, the Han people in Hubei province have higher gene frequencies of DRB1*0901, *1001, *0803; DQB1*0303, *0502 and DPB1*0501, *0202; and lower gene frequencies of DRB1*0301, *0401, *1301; DQB1*0201, *0603 and DPB1*0401, suggesting that Hubei Hans have their own layout of HLA class II allele frequencies.

CONCLUSION

These data may serve as normal reference values for the Han population in south China.

An ambulant porcine model of acid reflux used to evaluate endoscopic gastroplasty

BACKGROUND

There is a lack of suitable models for testing of therapeutic procedures for gastro-oesophageal reflux disease. Endoscopic sewing methods might allow the development of a new less invasive surgical approach to treatment of gastrointestinal disorders.

AIMS

To develop an animal model of gastro-oesophageal reflux for testing the efficacy of a new antireflux procedure, endoscopic gastroplasty, performed at flexible endoscopy without laparotomy or laparoscopy.

METHODS

At endoscopy a pH sensitive radiotelemetry capsule was sewn to the oesophageal wall, 5 cm above the lower oesophageal sphincter, in six large white pigs. Ambulant pH recordings (48-96 hours; total 447 hours) were obtained. The median distal oesophageal pH was 6.8 (range 6.4-7.3); pH was less than 4 for 9.3% of the time. After one week, endoscopic gastroplasty was performed by placing sutures below the gastro-oesophageal junction, forming a neo-oesophagus of 1-2 cm in length. Postoperative manometry and pH recordings (24-96 hours; total 344 hours) were carried out.

RESULTS

Following gastroplasty, the median sphincter pressure increased significantly from 3 to 6 mm Hg and in length from 3 to 3.75 cm. The median time pH was less than 4 decreased significantly from 9.3% to 0.2%.

CONCLUSIONS

These are the first long term measurements of oesophageal pH in ambulant pigs. The finding of spontaneous reflux suggested a model for studying treatments of reflux. Endoscopic gastroplasty increased sphincter pressure and length and decreased acid reflux.

Nebulized nitroglycerin in children with pulmonary hypertension secondary to congenital heart disease

Pulmonary hypertension continues to be a major cause of morbidity and mortality, despite new treatments. Since inhaled nitric oxide has been reported to be effective in some cases, we investigated using nebulized nitroglycerine to treat pulmonary hypertension in children with congenital heart disease. Four children (ages 6-72 months) with severe pulmonary hypertension secondary to congenital heart disease (all with membranous ventricular septal defect, undergoing cardiac catheterization) were given 3 cc of nebulized normal saline over 10 min as placebo control, followed by nebulized nitroglycerine (20 micrograms/Kg in 3 cc normal saline). Normal saline administration did not elicit any change, but nitroglycerine administration resulted in the following changes (mean +/- SE, paired statistics): systolic pulmonary artery pressure from 68 +/- 8 to 53 +/- 6 at 10 min into treatment (P 0.006), mean pulmonary artery pressure 47 +/- 4 to 38 +/- 4 (P 0.005), heart rate 131 +/- 8 to 127 +/- 7 (P 0.13), systolic blood pressure 85 +/- 8 to 88 +/- 3 (P 0.7), mean blood pressure 59 +/- 6 to 63 +/- 4 (P 0.5). These results indicate that nebulized nitroglycerine may be an effective, easy to administer, inexpensive, and safe alternative for treatment of severe pulmonary hypertension in children with congenital heart disease, especially in areas where other treatments such as extracorporeal membrane oxygenation or inhaled nitric oxide are inaccessible.

A randomised controlled comparison of injection, thermal, and mechanical endoscopic methods of haemostasis on mesenteric vessels

BACKGROUND AND AIMS

A randomised controlled comparison of haemostatic efficacy of mechanical, injection, and thermal methods of haemostasis was undertaken using canine mesenteric vessels to test the hypothesis that mechanical methods of haemostasis are more effective in controlling haemorrhage than injection or thermal methods. The diameter of arteries in human bleeding ulcers measures up to 3.45 mm; mesenteric vessels up to 5 mm were therefore studied.

METHODS

Mesenteric vessels were randomised to treatment with injection sclerotherapy (adrenaline and ethanolamine), bipolar diathermy, or mechanical methods (band, clips, sewing machine, endoloops). The vessels were severed and haemostasis recorded.

RESULTS

Injection sclerotherapy and clips failed to stop bleeding from vessels of 1 mm (n = 20) and 2 mm (n = 20). Bipolar diathermy was effective on 8/10 vessels of 2 mm but failed on 3 mm vessels (n = 5). Unstretched elastic bands succeeded on 13/15 vessels of 2 mm but on only 3/10 vessels of 3 mm. The sewing machine achieved haemostasis on 8/10 vessels of 4 mm but failed on 5 mm vessels (n = 5); endoloops were effective on all 5 mm vessels (n = 5).

CONCLUSIONS

Only mechanical methods were effective on vessels greater than 2 mm in diameter. Some mechanical methods (banding and clips) were less effective than expected and need modification. Thermal and (effective) mechanical methods were significantly (p < 0.01) more effective than injection sclerotherapy. The most effective mechanical methods were significantly more effective (p < 0.01) than thermal or injection on vessels greater than 2 mm.

[Observation on the changes of lipid peroxidation in neonates with sclerema]

Thirty-six hospitalized newborn infants with sclerema (case group), which were divided into mild group(n = 18) and severe group(n = 18), and 28 normal neonates (normal control group) were selected to measure the changes of blood lipid peroxidation (LPO) and superoxide dismutase(SOD) so as to study the role of free radicals and lipid peroxide injury the pathogenesis of the entity. The results showed that the plasma LPO contents were significantly increased and SOD were significantly decreased in the case group when compared with those in the normal group (P < 0.01). The plasma LPO was significantly higher and SOD activity was significantly lower in the severe group than those in the mild group (P < 0.01). The study indicates that the free radicals produced in sclerema neonatorum are great in amount and suggests that free radicals possibly participate in the pathogenesis of the disease.

N-acyl-homoserine lactone-mediated regulation of phenazine gene expression by Pseudomonas aureofaciens 30-84 in the wheat rhizosphere

Pseudomonas aureofaciens 30-84 is a soilborne bacterium that colonizes the wheat rhizosphere. This strain produces three phenazine antibiotics which suppress take-all disease of wheat by inhibition of the causative agent Gaeumannomyces graminis var. tritici. Phenazines also enhance survival of 30-84 within the wheat rhizosphere in competition with other organisms. Expression of the phenazine biosynthetic operon is controlled by the phzR/phzI N-acyl-homoserine lactone (AHL) response system (L. S. Pierson III et al., J. Bacterial 176:3966-3974, 1994; D. W. Wood and L. S. Pierson III, Gene 168:49-53, 1996). By using high-pressure liquid chromatography coupled with high-resolution mass spectrometry, the AHL produced by PhzI has now been identified as N-hexanoyl-homoserine lactone (HHL). In addition, the ability of HHL to serve as an interpopulation signal molecule in the wheat rhizosphere has been examined by using isogenic reporter strains. Disruption of phzI reduced expression of the phenazine biosynthetic operon 1,000-fold in the wheat rhizosphere. Coinoculation of an isogenic strain which produced the endogenous HHL signal restored phenazine gene expression in the phzI mutant to wild-type levels in situ. These results demonstrate that HHL is required for phenazine expression in situ and is an effective interpopulation signal molecule in the wheat rhizosphere.

Cutting thread at flexible endoscopy

BACKGROUND

New thread-cutting techniques were developed for use at flexible endoscopy. A guillotine was designed to follow and cut thread at the endoscope tip. A new method was developed for guiding suture cutters. Efficacy of Nd: YAG laser cutting of threads was studied. Experimental and clinical experience with thread-cutting methods is presented.

METHODS

A 2.4 mm diameter flexible thread-cutting guillotine was constructed featuring two lateral holes with sharp edges through which sutures to be cut are passed. Standard suture cutters were guided by backloading thread through the cutters extracorporeally. A snare cutter was constructed to retrieve objects sewn to tissue. Efficacy and speed of Nd: YAG laser in cutting twelve different threads were studied.

RESULTS

The guillotine cut thread faster (p < 0.05) than standard suture cutters. Backloading thread shortened time taken to cut thread (p < 0.001) compared with free-hand cutting. Nd: YAG laser was ineffective in cutting uncolored threads and slower than mechanical cutters. Results of thread cutting in clinical studies using sewing machine (n = 77 cutting episodes in 21 patients), in-vivo experiments (n = 156), and postsurgical cases (n = 15 over 15 years) are presented.

CONCLUSIONS

New thread-cutting methods are described and their efficacy demonstrated in experimental and clinical studies.

Percutaneous transluminal balloon pulmonary valvuloplasty using domestic balloon catheter for congenital pulmonary valve stenosis in children

OBJECTIVE

To estimate the effect of percutaneous balloon pulmonary valvuloplasty (PBPV) using domestic balloon catheter for congenital pulmonary valve stenosis (PVS) in infants and children.

PATIENTS AND METHODS

The data of 70 patients aged from 1.5 to 12 years (mean 5.5 +/- 3.4 years) who underwent PBPV using domestic balloon catheter for PVS in our institution were reviewed. Sixty-six patients had dome-shaped valve stenosis, and 4 had displastic valve stenosis. SaO2 reduced in 5 patients and associated open foramen ovale was noted in 23. Predilatation, right ventricular systolic pressure ranged from 60 to 234 mmHg (mean 115.75 +/- 36.15 mmHg). The systolic gradient (delta P) from right ventricle to pulmonary artery was 89.92 +/- 38.25 mmHg. Balloon diameter was selected 120%-142% of pulmonary valve annulus diameter (mean 132%). All patients were followed up for 3 months-4 years by means of clinical examination. ECG, 2D-UCG, and Doppler-UCG.

RESULTS

After dilatation, delta P reduced from 89.92 +/- 38.25 to 14.65 +/- 11.40 mmHg (P < 0.001). The rate of decrease in transvalve gradient (delta P) was 83.7%. No patients experienced procedure-related events. Mid-term follow-up showed that no patients had clinical and instrumental complications. Doppler and ECG analyses showed that delta P did not change significantly similar to immediate gradient after PBPV and right ventricular hypertrophy disappeared progressively 6 months after PBPV.

CONCLUSIONS

PBPV is a useful, safe and definitive procedure in the treatment of isolated PVS in infants and children. The properties and features of the balloon catheter produced by Shanghai Med-Tech Factory are similar to those of Med-Tech balloon catheter of U.S.A.

Antireflux operations at flexible endoscopy using endoluminal stitching techniques: an experimental study

BACKGROUND

Three antireflux operations-gastroplasty, fundoplication, and anterior gastropexy-were developed for performance at flexible endoscopy without laparotomy or laparoscopy.

METHODS

An endoscopic sewing machine mounted on a standard gastroscope, endoscopic knotting devices, overtube, and nylon thread were used to perform these operations in adult beagle dogs.

RESULTS

Gastroplasty (n = 10) was accomplished by suturing the anterior and posterior wall of the stomach to create a gastric tube (neoesophagus) along the lesser curve. An anatomic arrangement similar to fundoplication (n = 6) was achieved by invaginating the esophagus and fixing it to the stomach 2 cm distal to the cardioesophageal junction. Anterior gastropexy (n = 6) was performed using a technique similar to that used in creating percutaneous gastrostomies. There was no mortality. Ninety percent of sutures were seen at repeat endoscopy at 4 to 8 week intervals. The gastroplasty group was selected for more extensive evaluation. Manometry using a three-channel perfused catheter system before and after the procedures showed an increase in the lower esophageal sphincter pressure (preoperative median 4.6 mm Hg; post-operative median 13.33 mm Hg, p = 0.008) and cardiac yield pressures (preoperative median 10 mm Hg; postoperative median 19 mm Hg, p = 0.007).

CONCLUSIONS

This study demonstrates the feasibility of performing antireflux operations at flexible endoscopy, without laparoscopy or laparotomy, by use of endoluminal suturing techniques.

Molecular analysis of genes encoding phenazine biosynthesis in the biological control bacterium. Pseudomonas aureofaciens 30-84

The DNA sequence of five contiguous open reading frames encoding enzymes for phenazine biosynthesis in the biological control bacterium. Pseudomonas aureofaciens 30-84 was determined. These open reading frames were named phzF, phzA, phzB, phzC and phzD. Protein PhzF is similar to 3-deoxy-D-arabino-heptulosonate-7-phosphate synthases of solanaceous plants. PhzA is similar to 2,3-dihydro-2,3-dihydroxybenzoate synthase (EntB) of Escherichia coli. PhzB shares similarity with both subunits of anthranilate synthase and the phzB open reading frame complemented an E. coli trpE mutant deficient in anthranilate synthase activity. Although phzC shares little similarity to known genes, its product is responsible for the conversion of phenazine-I-carboxylic acid to 2-hydroxy-phenazine-I-carboxylic acid. PhzD is similar to pyridoxamine phosphate oxidases. These results indicate that phenazine biosynthesis in P. aureofaciens shares similarities with the shikimic acid, enterochelin, and tryptophan biosynthetic pathways.

Knot tying at flexible endoscopy

Four new knotting techniques were developed for use at flexible endoscopy: (1) half hitches tied with knot-pusher, (2) thread-locking device, (3) self-tightening slip-knot, and (4) externally releasable knot. Remoteness from site of action, access through small-diameter orifice, and difficulty in applying lateral traction to tighten knots are problems met in knot tying at endoscopy. All four knotting techniques were studied in experiments on postmortem human stomachs and used for radio-telemetry studies and anti-reflux operations in survival studies in dogs using endoscopic sewing techniques. Half hitches tied at endoscopy with a knot-pusher were also used in human studies to treat esophageal reflux and secure pH radio-telemetry capsules for long-term measurements. Externally releasable knots were used to secure nasogastric tubes to the stomach of five patients for long-term nutrition. Knot tying is feasible at flexible endoscopy by a variety of new techniques. Endoscopically tied knots can be as secure as surgically hand-tied knots and have been used successfully in man.

Pichinde virus-induced respiratory failure due to obstruction of the small airways: structure and function

Respiratory distress that leads to death is seen in patients with Lassa fever. The development of this respiratory problem was studied using a Pichinde virus model (10(4) plaque forming units, IP, survival time 20 +/- 1 days) in strain 13 guinea pigs (n = 35, 229-353 g) of this lethal human contagious infectious disease. Extravascular lung water to bloodless dry lung weight (EVLW/BDLW) ratio showed a modest yet significant increase in animals 13 and 18-21 days postinoculation (PI). In contrast, residual lung blood and lung radioactive 125I-labeled human serum albumin activity index were elevated only in the 18- to 21-day group. These data are consistent with the progressive severity of perivascular edema, lymphocytic pneumonitis, and some alveolar protein between days 13 and 18-21 PI. Lymphocytic pneumonitis appeared to be distributed near most airways and was proportional to the degree of Pichinde virus antigen staining of alveolar macrophages, large mononuclear cells within the pulmonary vascular and extravascular spaces, and alveolar-capillary membranes. These findings suggest that lymphocyte recruitment to the lung reflects the Pichinde virus-induced cell-mediated immune response. Obstructed small bronchi with some lumenal cell debris and hypertrophied epithelial cells were found associated with the areas of marked pneumonitis. The severe hypoxemia and modest anaerobic metabolism in association with marked tachypnea and normocapnia are consistent with small airway obstruction and wasted ventilation, since no change in arterial blood pressure, heart rate, hematocrit, hemoglobin, or blood volume was noted. These data suggest that Pichinde virus-induced respiratory failure was due to obstruction of the small airways with wasted ventilation in association with lymphocytic pneumonitis.