[Probe into the virtual medical instruments]

With the use of 3DSMAX and AUTO CAD 2000, we have practiced the dynamic simulation of the virtual medical instrument, which is very useful in design. The engineer and doctor can watch a product and change it before making so as to save the time of design and to improve the quality.

The effects of sensitization and hypersensitivity reaction on transepithelial antigen transport of rat nasal mucosa

METHODS

The prevalence of airway allergy is very high. The ways that antigen passes across the airway tract epithelial barrier are not well understood. This study uses a model antigen, horseradish peroxidase (HRP), to sensitize and challenge the respiratory tract in the rat model.

RESULTS

The results showed increases in HRP endosomes in nasal epithelial cells 5 minutes after HRP challenge in the sensitized rats compared with controls, which were further increased 30 minutes after HRP challenge, as well as with the paracellular region filled with HRP products. Meanwhile, mast cells were activated as shown by degranulation. Analysis of cell type showed that there were many more HRP endosomes in the nonciliated cells and there were many more nonciliated cells in the nasal mucosa of the sensitized rats.

CONCLUSION

The results demonstrate that sensitization promotes airway mucosal epithelial cells' uptake and transport of specific antigen and that mast cells may play certain roles in this process.

Abnormal gastric slow waves in patients with functional dyspepsia assessed by multichannel electrogastrography

The aim of this study was to utilize multichannel electrogastrography to investigate whether patients with functional dyspepsia had impaired propagation or coordination of gastric slow waves in the fasting state compared with healthy controls. The study was performed in 10 patients with functional dyspepsia and 11 healthy subjects. Gastric myoelectrical activity was measured by using surface electrogastrography with a specially designed four-channel device. The study was performed for 30 min or more in the fasting state. Special computer programs were developed for the computation of the propagation and coupling of the gastric slow wave. It was found that, compared with the healthy controls, the patients showed a significantly lower percentage of slow wave propagation (58.0 +/- 8.9 vs. 89.9 +/- 2.6%, P < 0.002) and a significantly lower percentage of slow wave coupling (46.9 +/- 4.4 vs. 61.5 +/- 6.9%, P < 0.04). In addition, the patients showed inconsistencies in the frequency and regularity of the gastric slow wave among the four-channel electrogastrograms (EGGs). It was concluded that patients with functional dyspepsia have impaired slow wave propagation and coupling. Multichannel EGG has more information than single-channel EGG for the detection of gastric myoelectrical abnormalities.

Fluorescence-based directed termination PCR: direct mutation characterization without sequencing

We describe a fluorescence-based directed termination PCR (fluorescent DT-PCR) that allows accurate determination of actual sequence changes without dideoxy DNA sequencing. This is achieved using near infrared dye-labeled primers and performing two PCR reactions under low and unbalanced dNTP concentrations. Visualization of resulting termination fragments is accomplished with a dual dye Li-cor DNA sequencer. As each DT-PCR reaction generates two sets of terminating fragments, a pair of complementary reactions with limiting dATP and dCTP collectively provide information on the entire sequence of a target DNA, allowing an accurate determination of any base change. Blind analysis of 78 mutants of the supF reporter gene using fluorescent DT-PCR not only correctly determined the nature and position of all types of substitution mutations in the supF gene, but also allowed rapid scanning of the signature sequences among identical mutations. The method provides simplicity in the generation of terminating fragments and 100% accuracy in mutation characterization. Fluorescent DT-PCR was successfully used to generate a UV-induced spectrum of mutations in the supF gene following replication on a single plate of human DNA repair-deficient cells. We anticipate that the automated DT-PCR method will serve as a cost-effective alternative to dideoxy sequencing in studies involving large-scale analysis for nucleotide sequence changes.

Mutational spectrum analysis of RNase H(35) deficient Saccharomyces cerevisiae using fluorescence-based directed termination PCR

Mutational spectrum analysis has become an informative genetic tool to understand those protein functions involved in mutation avoidance pathways since specific types of mutations are often associated with particular protein defects involved in DNA replication and repair. In this study, we describe a novel, fluorescence-based procedure for direct determination of deletions and insertions with 100% accuracy. We performed two complementary directed termination PCR with near infrared dye-labeled primers, followed by visualization of termination fragments using an automated Li-cor DNA sequencer. This method is used for rapid analysis of mutational spectra generated in nuclease-defective strains of Saccharomyces cerevisiae to elucidate the role of RNase H(35) in RNA primer removal during DNA replication and in mutation avoidance. Strains deficient in RNH35 displayed a distinct spontaneous mutation spectrum of deletions characterized by a unique 4 bp deletion in a lys2-Bgl allele. This was in sharp contrast to strains deficient in rad27 that displayed duplication mutations. Further analysis of mutations in a rnh35/rad27 double mutant revealed a mixed spectrum. These results indicate that RNase H(35) may participate in a redundant pathway in Okazaki fragment processing and that mutational spectra caused by protein deficiencies may be more intermediate-specific than pathway-specific.

High-resolution NMR and computer modeling studies of the cannabimimetic aminoalkylindole prototype WIN-55212-2

Aminoalkylindoles (AAIs), although structurally dissimilar from the classical cannabinoids (CCs), are known to be capable of binding to cannabinoid receptors and of evoking cannabimimetic responses. However, their mode of binding remains unknown. In this communication, we have carried out further studies on the AAI prototype (R)-[2, 3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrrolo[1,2,3-de]-1, 4-benzoxazin-6-yl](1-naphthalenyl)methanone (WIN-55212-2, 1) by the combined use of high-resolution 2D NMR and computer modeling. Our results suggest that the minimum energy conformations of the molecule 1 have distinct pharmacophoric features: (i) The naphthyl ring is oriented off the plane of the benzoxazine ring by approximately 59 degrees with the carbonyl C=O group pointing toward the C2-CH(3) group. (ii) At the C10-position the axial morpholinomethyl conformation is preferred over the equatorial in order to relieve a steric interaction with the C2-methyl group. The preferred conformer as defined by the three key pharmacophores, naphthyl, morpholino, and 3-keto groups, shows that the morpholinyl ring of the molecule 1 deviates from the plane of the benzoxazine ring by about 32 degrees and orients in the left molecular quadrant. This model supports the hypothesis that a certain deviation of the morpholino group from the plane of the indole ring in compound 1 is essential for cannabimimetic activity. We postulate that such an alignment by the respective pharmacophores allows them to interact optimally with the receptor. The results should help us to better understand the pharmacophoric requirements of the AAIs and serve as a basis for future SAR studies and drug design.

Terminal branch haplotype analysis: a novel approach to investigate newly arisen variants of mitochondrial DNA in natural populations

The discrimination of recent mutational derivatives from ancestral variation is a critical antecedent to any effort which aims to identify the factors modulating the rates of origin and persistence of new mutants. We propose that newly arisen mtDNA variants, which we designate as terminal branch haplotypes (TBHs), can be recognized by joint sequencing and phylogenetic analysis. This study examined mtDNA diversity in natural populations of the brown bullhead (Ameiurus nebulosus) from four heavily contaminated sites and three relatively pristine locations. While sequence analysis of the mtDNA D-loop region revealed that TBHs were prevalent in these populations, contaminant exposure appeared to play a minor role in their generation. Instead, most TBHs likely arose due to spontaneous mutations with variation in their incidence among sites reflecting the impact of demographic factors.

Intraindividual sequence diversity and a hierarchical approach to the study of mitochondrial DNA mutations

Investigations of intraindividual sequence diversity in mtDNA are a key step in exploring the linkage between somatic mutations in mtDNA and mitochondrial genome evolution. This paper reports a directional cloning procedure enabling the isolation of multiple copies of the D-loop region of the mitochondrial genome from the fish Ameiurus nebulosus. Sequence analysis of 708 D-loop molecules revealed eight mutants, an average intraindividual mutation frequency of 1.12%. Three different types of mutations were detected but each derived from a single mutational event. By contrasting the spectrum of nucleotide variation at multiple biological levels, one can investigate the effects of spontaneous mutations on genome evolution. Such hierarchical analysis suggested shifts in the type and distribution of mtDNA (mitochondrial DNA) mutations at different biological levels, indicating the need to recognize three different rates of mtDNA sequence change from the cellular to population level.

Role of lipid modifications in targeting proteins to detergent-resistant membrane rafts. Many raft proteins are acylated, while few are prenylated

Sphingolipid and cholesterol-rich Triton X-100-insoluble membrane fragments (detergent-resistant membranes, DRMs) containing lipids in a state similar to the liquid-ordered phase can be isolated from mammalian cells, and probably exist as discrete domains or rafts in intact membranes. We postulated that proteins with a high affinity for such an ordered lipid environment might be targeted to rafts. Saturated acyl chains should prefer an extended conformation that would fit well in rafts. In contrast, prenyl groups, which are as hydrophobic as acyl chains but have a branched and bulky structure, should be excluded from rafts. Here, we showed that at least half of the proteins in Madin-Darby canine kidney cell DRMs (other than cytoskeletal contaminants) could be labeled with [3H]palmitate. Association of influenza hemagglutinin with DRMs required all three of its palmitoylated Cys residues. Prenylated proteins, detected by [3H]mevalonate labeling or by blotting for Rap1, Rab5, Gbeta, or Ras, were excluded from DRMs. Rab5 and H-Ras each contain more than one lipid group, showing that hydrophobicity alone does not target multiply lipid-modified proteins to DRMs. Partitioning of covalently linked saturated acyl chains into liquid-ordered phase domains is likely to be an important mechanism for targeting proteins to DRMs.

Directed termination of the polymerase chain reaction: kinetics and applications in mutation detection

We describe a PCR-based method (DT-PCR) that integrates both DNA amplification and directed chain termination into a single-step process. This method exploits unbalanced nucleotide concentrations to induce the polymerase chain reaction to terminate at specific nucleotide sites, leading to the generation of two sets of nested termination fragments from genomic DNA. The kinetic mechanism underlying the termination process is outlined and the application of this method to the detection and characterization of mutations in fragments as long as 1 kb is described. The method is effective for the analysis of both haploid and diploid genomes, and not only allows the recognition of both indels (insertions and deletions) and nucleotide substitutions, but also enables the determination of their position in a single-step fashion.

Analysis of electronic structures of physostigmine analogs

AIM

To elucidate the action mechanism and structural prerequisites of 21 physostigmine analogs as acetylcholinesterase inhibitors at the molecular level, and help the rational design of these dihydroindoline inhibitors.

METHODS

Initial structures of these compounds were built and minimized by SYBYL 6.2 molecular modeling software. Conformations of those molecules with the highest predictive abilities in the Comparative Molecular Field Analysis model were chosen to the semiempirical quantum chemical calculations.

RESULTS

(1) The highest occupied molecular orbital (HOMO) consisted mainly of the orbitals in phenyl group and N1 atom; the lowest unoccupied molecular orbital (LUMO) of the molecules was contributed from phenyl group and C11 atom. While the HOMO energies did not show any recognizable relationship with activity, the LUMO energies showed a decreased tendency with increasing activity. The active compounds showed lower LUMO energies. (2) The carbon atom (C11) had the most positive net atom charge. The most active compound had the most positive charge on this carbon, but had the lower charges on the carbonyl oxygen (O12) which was the most negative charge atom. (3) The bond order of carbon-oxygen bond (C11-O10) was invariant across the series of the compounds. (4) Compounds with too high or too low total dipole moment had lower activities, while the most active one had a lower molecular polarizability.

CONCLUSION

A molecular model was suggested to explain the possible mode of action by which these compounds inhibit acetylcholinesterase.

A 3D-QSAR study on ginkgolides and their analogues with comparative molecular field analysis

Comparative molecular field analysis (CoMFA), a three-dimensional quantitative structure-activity relationship (3D-QSAR) paradigm was used to study the correlation between the physicochemical properties and the in vitro bioactivities of ginkgolide analogues. The correlation derived from CoMFA analysis has a good predictive capability. Based on the result of CoMFA analysis, we designed some compounds. Pharmacological assay indicated that three of these new designed compounds are 2 and 4 times more potent than that of ginkgolides.

Binding conformers searching method for ligands according to the structures of their receptors and its application to thrombin inhibitors

AIM

To develop a method of finding binding conformers for ligands according to the three-dimensional structures of their receptors.

METHODS

Combining the systematic search method of ligand with the molecular docking approach of ligand fitting into its receptor, we developed a binding conformer searching method for ligands.

RESULTS

The binding conformers of phosphonopeptidyl thrombin inhibitors were recognized. The binding (interaction) energies between these inhibitors and thrombin were calculated with molecular mechanical method.

CONCLUSION

Both of the total binding energies and steric binding energies have good correlations with the inhibitory activities of these thrombin inhibitors, demonstrating that our approach is reasonable. It can also be used to explain the inhibition mechanism of thrombin interacting with these inhibitors.

Spin trapping study in the lungs and liver of F344 rats after exposure to ozone

Fischer 344 rats were injected with the spin traps C-phenyl N-tert-butyl nitrone (PBN, 150 mg/kg bw, ip) or 4-pyridine-N-oxide N-tert-butyl nitrone (POBN, 775 mg/kg bw, ip), and exposed to clean air or 2 ppm ozone for two hours. The presence of spin adducts was determined by electron paramagnetic resonance (EPR) spectroscopy of chloroform extracts of lung and liver homogenates. No significant levels of adducts were detected in the lungs of air control animals. Benzoyl N-tert-butyl aminoxyl, attributed to direct reaction of ozone with PBN, and tert-butyl hydroaminoxyl, the scission product of the hydroxyl adduct of PBN, were detected in the lungs of ozone exposed rats. EPR signals for carbon-centred alkoxyl and alkyl adducts were also detected with PBN in the lungs and liver of animals exposed to ozone. With POBN, only carbon-centred alkyl radicals were detected. Senescent, 24 months old rats were found to retain about twice more 14C-PBN in blood, heart and lungs by comparison to juvenile, 2 months old animals. Accordingly, the EPR signals were generally stronger in the lungs of the senescent rats by comparison to juvenile rats. Together, the observations were consistent with the previously proposed notion that a significant flux of hydrogen peroxide produced from the reaction of ozone with lipids of the extracellular lining, or from activated macrophages in the lungs could be a source of biologically relevant amounts of hydroxyl radical.

Inhibitory effect of phenyl N-terf-butyl nitrone on Kupffer cell phagocytosis

Light microscopy studies of rat liver were conducted after injection of India ink. The data indicated that Kupffer cell phagocytosis was inhibited by C-phenyi-N-tert-butyl nitrone (PBN), as well as by the Kupffer cell antagonist gadolinium chloride.

3D-QSAR study on ether and ester analogs of artemisinin with comparative molecular field analysis

Comparative molecular field analysis (CoMFA), a three-dimensional quantitative structure-activity relationship (3D-QSAR) paradigm, was used to study the correlations between the physicochemical properties and the in vitro activities of a series of ether and ester analogs of artemisinin. Four alignment models were used in the CoMFA investigation. The correlations derived from CoMFA analysis with the four alignments proved all to have good predictive values. The steric field predictive model of alignment B is accordant with the experimental results of Avery M A, et al: J Med Chem 1993; 36: 4264-75. The electrostatic field predictive results of alignments A, B, and C are consistent with our previous result of quantum chemical calculation. The highest rcross2 of alignment D, indicated that the side chain of -C6-O2-O1-C10-O3-C7-O4-C12-O5- and atom C16 are important groups of artemisinin analogs for antimalarial activity.

[Intraperitoneal perfusion of compound injection of salvia miltiorrhiza with dachengqi decoction in treating adhesive intestinal obstruction]

47 cases of adhesive intestinal obstruction after decompression operation were treated with intraperitoneal perfusion of compound injection of Salvia Miltiorrhizam intraperitoneally before closing the abdominal cavity and Dachengqi decoction oral given post-operatively. Follow up study for 2-9 years showed the effective rate was 100% except one case died of other unrelevant disease. Another 38 cases of the same disease and same operation procedure were selected as the control group, which were given antibiotics intraperitoneally before closing the abdominal cavity. The effective rate was 73.38%. The result in the therapeutic group was significantly better than that in the control group (P < 0.01).

[Measurement of plasma fibronectin concentrations in normal pregnancy and pregnancy induced hypertension and its clinical significance]

Plasma fibronectin (Fn) concentrations were measured in 472 cases of normal pregnancy and pregnancy induced hypertension (PIH), and 50 cases of normal individuals using radioimmune turbidity method. The results showed that the mean value of Fn in 390 cases of normal pregnancy with various weeks of gestation was 445 +/- 159 mg/L significantly higher than the average of 299 +/- 76 mg/L in 50 cases of normal individuals and 250 +/- 89 mg/L in 22 cases of normal women. As pregnancy progressed, the plasma Fn value increased slightly. The 82 cases of PIH had an average plasma Fn level of 783 +/- 168 mg/L, which was significantly higher than that in normal pregnancy. If plasma Fn concentrition of 600 mg/L was used as cut-off point for the diagnosis of PIH, the sensitivity reached to 83%. Plasma Fn level increased as the disease of PIH progressed. Therefore, plasma Fn concentrition could be used as a reliable indicator to the severity of PIH.

The role of free radicals in the development of radiation interstitial pneumonitis

We examined the morphologic changes in the lung tissue of Wistar rats after chest irradiation and determined sequentially the content of free radicals (FR) using electron spin resonance. The activity of superoxide dismutase (SOD) was also assessed using the chemical glow method of xanthine oxidase. After chest irradiation, the content of FR in the lung progressively increased and the activity of SOD progressively decreased. We discuss here the role of the FR in the developing process of radiation interstitial pneumonitis.

[Clinical effect of chemotherapy combined with Chinese herbs and western drugs on leukocytes of gastric cancer patients]

This study observed the effect of chemotherapy combined with Chinese herbs and western drugs on white blood cell count in 31 patients with gastric cancer. These patients were divided into 3 groups: (1) Fu Zheng (strengthen the body resistance) with invigorating the Spleen and Kidney recipe; (2) Fu Zheng with western drugs raising WBC and enhancing immunity; (3) Gong Xiao (eliminating the evil factors and mass) with promoting blood circulation to remove blood stasis recipe or eliminating the evil factors and mass recipe. After chemotherapy, the mean of WBC count was greater than 4.0 X 10(9)/L in group I; less than 3.5 X 10(9)/L in group II; less than 3.0 X 10(9)/L in group III. Because of WBC count below 3.0 X 10(9)/L, in group II there were 5 cases (5/14) whose chemotherapies had to be discontinued, and in group III there were 4 cases (4/6). While all patients were completed their chemotherapies in group I. Its statistical difference was significant (P less than 0.05). It suggested that invigorating the Spleen and Kidney recipe had specific effect on decreasing the toxicity and side effect of chemotherapy, preventing bone marrow suppression and leukopenia, and was better than western drugs used in group II. It showed in the treatment of cancer with TCM, we must pay attention to the relationship between the Fu Zheng and the Gong Xiao.

Differences in glycoprotein complexes associated with IgM and IgD on normal murine B cells potentially enable transduction of different signals

Studies presented here demonstrate that IgM and IgD molecules on normal murine B lymphocytes exist in different, noncovalently associated molecular complexes containing distinct but potentially related glycoproteins. The glycoproteins in these complexes, particularly those associated with IgD, show striking differences in various lymphoid organs and in X-linked immunodeficient (Xid) mice. These differences are due in part to post-translational processing. They apparently reflect the differential expression of the Ig-associated glycoproteins in the various B cell subpopulations and lineages and the differential distribution of the subpopulations and lineages in the various lymphoid organs. In addition, they reflect structural differences in the IgM and IgD complexes which, we suggest, permit differential signal transduction by IgM and IgD on the same B cell.

Heparin inhibits EcoRI endonuclease cleavage of DNA at certain EcoRI sites

Studies presented here demonstrate that heparin inhibits EcoRI endonuclease cleavage of DNA whereas related proteoglycans show no effect. The inhibition occurs at particular EcoRI sites that are near or overlap with palindromic sequences in the murine lambda 5 and Lyt-2 genes. Endogenous heparin from peritoneal mast cells co-isolates with DNA and inhibits digestion of peritoneal cell DNA at the inhibitable sites. Digestion of spleen DNA is inhibited at the same sites when commercial heparin is added prior to digestion. In both cases, the inhibition is abolished by pre-treating the DNA with heparinase. Thus, potential artifacts in restriction fragment length analyses could occur with DNA isolated either from cells that are naturally rich in heparin or from cells to which heparin has been added, e.g., as an anticoagulant.

Orthotopic homotransplantation of vascularized composite mandibular tissue in rabbits immunosuppressed with cyclosporine A

To develop the surgical model, composite mandibular tissue was transplanted at the same site. Revascularization was accomplished by end-to-end anastomosis of the facial vessels using standard microvascular techniques. A total of 33 vascularized composite mandibular tissue allografts were similarly performed between two incompatible strains of rabbit. In a control group of 9 animals, no immunosuppression was administered. All of these allografts were rejected acutely within 10 days after surgery. 7 allograft recipients were immunosuppressed with azathioprine and prednisone at 5 mg/kg.d and 2 mg/kg.d, respectively. Their allografts were also rejected acutely within 10 days. 17 allograft recipients were immunosuppressed with cyclosporine A (CsA). All allografts showed primary wound healing and hair growth and took on normal appearance. 8 of these recipients were given CsA at 5 mg/kg.d i.v. and their allografts were rejected at a mean time of 17.9 days. The remaining 9 recipients given CsA at 10 mg/kg.d i.v. rejected their allografts at a mean time of 36.1 days. In 3 of them, the rejection was reversed with CsA (20 mg/kg.d) injection for five days successfully, and one allograft survived more than 100 days. This pilot study suggests that the surgical model is reliable and that CsA will be useful as an immunosuppressive agent in the study of vascularized composite mandibular tissue allografts.

Observation on erythrocyte acetylcholinesterase (AChE) in infants and children with Hirschsprung's disease

In 31 cases of Hirschsprung's disease, the mean value of erythrocyte AChE activity was discovered to be 91.24 +/- 10.24 u/mL, being significantly higher than that from 127 normal children of 73.51 +/- 9.36 u/mL (P less than 0.001); whereas serum ChE mean value of 14.49 +/- 4.04 u/mL showed no difference from normal control (16.89 +/- 8.86 u/mL, P greater than 0.05). In addition, the erythrocyte AChE activity of six newborns with Hirschsprung's disease was also found to be much higher than its own normal control. It was therefore, concluded that this assay may be of supplementary diagnostic significance in diagnosing neonatal Hirschsprung's disease.