Shear modulus of porcine coronary artery: contributions of media and adventitia

The epicardial coronary arteries experience significant torsion in the axial direction due to changes in the shape of the heart during the cardiac cycle. The objective of this study was to determine the torsional mechanical properties of the coronary arteries under various circumferential and longitudinal loadings. The coronary artery was treated as a two-layer composite vessel consisting of intima-medial and adventitial layers, and the shear modulus of each layer was determined. Eight porcine hearts were obtained at a local abattoir, and their right coronary and left anterior descending arteries were isolated and tested in vitro with a triaxial torsion machine (inflation, longitudinal stretch, and circumferential twist). After the intact vessel was tested, the adventitia was dissected away, leaving an intact media that was then tested under identical triaxial loading conditions. We proposed a biomechanical analysis to compute the shear modulus of the adventitia from the measured shear moduli of the intact vessel and the media. To validate our predictions, we used four additional hearts in which the shear modulus of the adventitia was measured after dissection of media. Our results show that the shear modulus does not depend on the shear stress or strain but varies linearly with circumferential and longitudinal stresses and in a nonlinear way with the corresponding strains. Furthermore, we found that the shear modulus of the adventitia is larger than that of the intact vessel, which is larger than the vessel media. These results may have important implications for baroreceptor sensitivity, circulation of the vasa vasorum, and coronary dissection.

Generating MHC Class II+/Ii- phenotype after adenoviral delivery of both an expressible gene for MHC Class II inducer and an antisense Ii-RNA construct in tumor cells

Tumor cells engineered by gene transduction to be MHC Class II+/Ii- are novel APCs capable of presenting endogenous tumor antigen epitopes to activate T helper cells. The MHC Class II+/Ii- tumor cell phenotype is created by transfecting genes for either CIITA or IFN-gamma, and inhibiting induced Ii mRNA by an Ii reverse gene construct (Ii-RGC). Adenoviral vectors are preferred for the delivery of such genes because of high infection efficiency and ubiquity of the adenoviral receptor on many cell types and tumors. Here we show that at 5 MOI (multiplicity of infection), recombinant adenoviruses with CIITA or IFN-gamma genes converted virtually all MC-38 colon adenocarcinoma cells and Renca renal carcinoma cells in culture to MHC Class II+/Ii+ cells. A single recombinant adenovirus with both genes for IFN-gamma and Ii-RGC (rAV/IFN-gamma/Ii-RGC) efficiently induced the MHC Class II+/Ii- phenotype. Injection of tumor nodules with rAV/Ii-RGC and rAV/CIITA/IFN-gamma combined with a suboptimal dose of rAV/IL-2 induced a potent antitumor immune response. The methods are adaptable for producing enhanced genetic vaccines, attenuated virus vaccines (eg, vaccinia), and ex vivo cell-based vaccines (dendritic and tumor cells).

[The protective effect against Toxoplasma infection in mice immunized with laser-irradiated Toxoplasma tachyzoites]

AIM

To observe the level of immune responses and protective immunity in mice induced by laser-irradiated Toxoplasma tachyzoites (LIT).

METHODS

ICR mice were immunized with LIT. After one month, the mice were challenged with live Toxoplasma tachyzoites to observe the effect of LIT. Indirect immunofluorescence assay and ELISA were used to detect CD4+/CD8+ lymphocyte subpopulation and IgG antibody.

RESULTS

Immunization with LIT could partially protect the mice from Toxoplasma infection, prolong the survival time, enhance the CD4+/CD8+ ratio and produce specific IgG antibody.

CONCLUSION

Intraperitoneal injection with LIT can induce partial protective immunity and specifically elicit ICR mice to generate humoral and cell-mediated immune responses.

Modulation of Integrin-binding Selectivity by Mutation within the RGDLoop of Snake Venom Proteins: A Novel Drug Development Approach

Integrins are a family of heterodimeric class I transmembrane receptors, many of which bind to the RGD sequence in adhesive proteins and mediate the adhesive interactions of a variety of cells. The RGD motif has also been found in snake venom proteins that specifically inhibit integrin binding function and serve as potent integrin antagonists. The majority of these proteins interact with beta1 and beta3 associated integrins and their potency is at least 500-2000 times higher than short RGD peptides. Structural and functional studies suggest that the inhibitory potency of these proteins lies in subtle positional requirements of the tripeptide RGD that is harboured in a defined flexible loop. The integrin-binding specificity and selectivity of each of the proteins is controlled by amino acid residues in this loop in close vicinity to the RGD-motif. The review includes an overview of the structure and function of snake-venom integrin antagonists. The ability of these proteins to control platelet aggregation, cell adhesion and ligand binding is compared to that of short linear, cyclic RGD-peptides and RGD-containing proteins and the influence of modulation of amino acid residues flanking the RGD motif is also considered. The review is intended to provide insight into the development of novel inhibitors as drugs.

Blast waves produced by interactions of femtosecond laser pulses with water

The behaviors of the blast waves produced by femtosecond laser-water interactions, and the blast waves induced by laser self-focusing in air, have been investigated using optical shadowgraphy at a maximum intensity of 1 x 10(16) W/cm(2). The temporal evolution of the blast wave launched by the water plasma can be described by a planar blast wave model including source mass. An aneurismlike structure, due to the quick propagation inside a hollow channel formed by laser self-focusing, is observed. The expansion of the channel in air is found to agree with a cylindrical self-similar blast wave solution.

Spatial distribution of high-energy electron emission from water plasmas produced by femtosecond laser pulses

High energy electrons emitted by water plasmas produced by a single or a multiple laser pulse are investigated. The multipulse mode greatly enhances the generation and the temperature of hot electrons. Directional emission of high energy electrons over 25 keV is observed in two symmetric directions with respect to the laser axis and at 46 degrees from the directions of the laser electric field. Two-dimensional particle-in-cell simulations reproduce well the experimental results and indicate that the acceleration mechanism of the high energy electrons is due mainly to the resonance absorption at the edge of the spherical droplets formed by the leading pulse.

Pathogenicity and antigenicity of a new influenza A (H5N1) virus isolated from duck meat

Avian influenza A viruses are the ancestral origin of all human influenza viruses. The outbreak of highly pathogenic (HP) avian H5N1 in Hong Kong in 1997 highlighted the potential of these viruses to infect and cause severe disease in humans. Since 1999, HP H5N1 viruses were isolated several times from domestic poultry in Asia. In 2001, a HP H5N1 virus, A/Duck/Anyang/AVL-1/2001 (Dk/Anyang), was isolated from imported frozen duck meat in Korea. Because of this novel source of HP H5N1 virus isolation, concerns were raised about the potential for human exposure and infection; we therefore compared the Dk/Anyang virus with HP H5N1 viruses isolated from humans in 1997 in terms of antigenicity and pathogenicity for mammals. At high doses, Dk/Anyang virus caused up to 50% mortality in BALB/c mice, was isolated from the brains and lymphoid organs of mice, and caused lymphopenia. Overall Dk/Anyang virus was substantially less pathogenic for mice than the H5N1 virus isolated from a fatal human case in 1997. Likewise, Dk/Anyang virus was apathogenic for ferrets. Dk/Anyang virus was antigenically distinguishable by hemagglutination-inhibition (HI) assay from human H5N1 viruses isolated in 1997 and avian H5N1 viruses isolated in 2001 in Hong Kong. Nevertheless, prior infection with Dk/Anyang virus protected mice from death after secondary infection with HP human H5N1 viruses. These results indicate that compared with HP human H5N1 viruses, Dk/Anyang virus is substantially less pathogenic for mammalian species. Nevertheless, the novel source of isolation of this avian H5N1 virus must be considered when evaluating the potential risk to public health.

Thyrotropin-releasing hormone receptors -- similarities and differences

Thyrotropin-releasing hormone (TRH) initiates its effects by interacting with cell-surface membrane receptors. Two G protein-coupled receptors for TRH, TRH receptor type 1 (TRH-R1) and TRH receptor type 2 (TRH-R2), have been cloned from mammals. In this review, we compare TRH-R1 and TRH-R2 with regard to their tIssue distribution, binding affinities for TRH and TRH analogs, basal and activated signaling activities and characteristics of internalization. TRH-R1 and TRH-R2 are distributed differently in the brain and peripheral tIssues, but exhibit indistinguishable binding affinities for TRH and TRH analogs. Although they both can be stimulated by TRH to similar maximal signaling levels, TRH-R2 exhibits higher basal signaling activity and is more rapidly internalized than TRH-R1. These differences in signaling and internalization properties are probably important in the distinct parts that TRH-R1 and TRH-R2 may play in mammalian physiology.

The neuroblastoma amplified gene, NAG: genomic structure and characterisation of the 7.3 kb transcript predominantly expressed in neuroblastoma

Amplification of the MYCN oncogene in neuroblastoma is associated with poor prognosis. The amplified unit of DNA can be up to 1 Mb in size and so could contain additional genes which affect tumour phenotype. The neuroblastoma amplified gene (NAG) gene was initially located 400 kb telomeric to MYCN at 2p24 and reported to be co-amplified in 5/8 (63%) cell lines and 9/13 (70%) tumours. The sequence of a 4.5 kb transcript was proposed from the analysis of overlapping cDNA clones. However, our Northern blot hybridisation experiments indicate that the main RNA species expressed in neuroblastoma is 7-8 kb in size. We describe for the first time the cloning and sequencing of the 7.3 kb transcript of the NAG gene together with its precise genomic location and full exon structure. The 5' end of the gene is located 30 kb telomeric to DDX1, with the two genes lying in opposite orientations. The 52 exons of the 7.3 kb transcript cover 420 kb of genomic DNA. In vitro translation studies confirmed the protein coding potential of the transcript. Co-amplification of the entire NAG gene with MYCN was found in 1/6 (17%) neuroblastoma cell lines and 10/50 (20%) primary tumours. Previous studies had measured co-amplification of only the 5' end of the gene, nearest to MYCN. In this study, co-amplification of the NAG gene was found to be significantly associated with low disease stage in MYCN-amplified tumours (P=0.0063).

Aquaporin expression in developing human teeth and selected orofacial tissues

The aquaporin (AQP) family of membrane channel proteins function as selective pores through which water, glycerol, and other small solutes cross the cell plasma membrane. To date, 11 members of this transporter family, designated AQP0-10, have been cloned and characterized in humans. The AQPs are differentially expressed in temporospatial patterns, where different AQPs demonstrate distinct tissue distributions that may reflect differing cell membrane transport functions. The purpose of this study was to evaluate AQP expression in the developing human teeth by RT-PCR and Western blot analysis. To access the generality of AQP expression, selected other orofacial tissues were studied by RT-PCR. The presence of all eleven human AQPs was screened in each tissue by RT-PCR. Positive amplification products were verified by direct DNA sequencing. AQPs 1, 3, 4, 5, 6, and 10 were identified by RT-PCR in developing teeth, and AQP1, 3, 5, and 6 were confirmed by Western blot analysis. AQP 4 was not detected by Western blot analysis, and we were unable to test for the recently identified AQP10 due to unavailability of antibodies. AQPs detected in other orofacial tissues by RT-PCR included gingiva (AQP3, 7, 10); Meckel's cartilage (AQP1, 3, 4, 5, 6); submandibular gland (AQP1, 3, 4, 5, 6, 7); masseter muscle (AQP1, 3, 4, 7, 8, 9,10); and infrahyoid muscle (AQP1, 3, 4,10). These results demonstrate that multiple aquaporins are expressed in developing teeth and in selected orofacial tissues.

Progastrin1-80 stimulates growth of intestinal epithelial cells in vitro via high-affinity binding sites

Proliferation and carcinogenesis of the large intestinal epithelial cells (IEC) cells is significantly increased in transgenic mice that overexpress the precursor progastrin (PG) peptide. It is not known if the in vivo growth effects of PG on IEC cells are mediated directly or indirectly. Full-length recombinant human PG (rhPG(1-80)) was generated to examine possible direct effects of PG on IEC cells. Surprisingly, rhPG (0.1-1.0 nM) was more effective than the completely processed gastrin 17 (G17) peptide as a growth factor. Even though IEC cells did not express CCK(1) and CCK(2) receptors (-R), fluorescently labeled G17 and Gly-extended G17 (G-Gly) were specifically bound to the cells, suggesting the presence of binding proteins other than CCK(1)-R and CCK(2)-R on IEC cells. High-affinity (K(d) = 0.5-1.0 nM) binding sites for (125)I-rhPG were discovered on IEC cells that demonstrated relative binding affinity for gastrin-like peptides in the order PG >or= COOH-terminally extended G17 >or= G-Gly > G17 > *CCK-8 (* significant difference; P < 0.05). In conclusion, our studies demonstrate for the first time direct growth effects of the full-length precursor peptide on IEC cells in vitro that are apparently mediated by the high-affinity PG binding sites that were discovered on these cells.

The influence of phorbol ester on the effect of tamoxifen in breast cancer cells

To investigate the correlation between the activity of kinases in the growth factor signal transduction pathway and the development of resistance of breast cancer to tamoxifen, reporter gene regulated by the regulating fragment of CCD1 was transfected into the MCF-7 cells, and the influence of tamoxifen on the reporter gene expression was examined under different conditions of TPA treatment. Our results showed that the reporter gene expression was inhibited by tamoxifen and promoted by TPA. Furthermore, tamoxifen exerts an agonist effect on the reporter gene expression when the cells was treated by TPA previously for 12 h. It is concluded that TPA could induce estrogen-like effect of tamoxifen on estrogen receptor positive breast cancer cells and it may be one of the mechanisms responsible for the development of tamoxifen resistance.

Tyrosine phosphatase inhibition enhances neurotrophin potency and rescues nigrostriatal neurons in adult rats

Neurotrophic factors regulate a variety of cellular processes, including neuronal survival during development and after injury. For instance, brain-derived neurotrophic factor (BDNF) can prevent the death of dopaminergic substantia nigra neurons in rats. Most neurotrophic factor receptors, such as TrkB for BDNF, are tyrosine kinases whose signaling is terminated by protein tyrosine phosphatases (PTPs). We tested the idea that inhibition of PTPs, and thus potentially enhancement of the efficiency of endogenous trophic factors and their receptors, would lead to increased neuronal survival. After a 2-week infusion of the small PTP inhibitor molecule peroxovanadium (pVa, pervanadate) close to the substantia nigra of adult rats, up to 66% of axotomized substantia nigra neurons had survived, compared to only 33% in control rats infused with PBS. PVa most likely affected TrkB and/or downstream signaling molecules, as ineffective doses of BDNF and pVa had a synergistic effect when given simultaneously, rescuing 82% of the neurons. PVa stimulated tyrosine hydroxylase (TH) expression in the noninjured substantia nigra but did not prevent axotomy-induced loss of TH. These results raise the possibility that PTP inhibition can prevent neuronal death by enhancing neurotrophic factor signaling pathways in the adult mammalian nervous system, identifies an important role for PTPs in neuronal functioning, and points to a novel small molecule treatment approach for neurologic disorders

Long-term retention of motor skill in macaque monkeys and humans

Remarkable human performance, such as playing the violin, is often based on motor skills that, once acquired, are retained for a long time. To examine how motor skills are retained, we trained monkeys and humans extensively to perform many visuomotor sequences and examined their performance after a long retention period of up to 18 months. For both monkeys and humans, we found strong evidence for long-term retention of motor skills. Each of the monkey subjects initially learned 6-18 sequences of button presses extensively by trial-and-error for up to 18 months. After a long retention period, they were asked to perform the previously learned (OLD) sequences together with completely new (NEW) sequences. The performance for OLD sequences was much better than for NEW sequences in terms of accuracy (assessed by the number of errors to criterion) and speed (assessed by the performance time). However, the retention was interfered with in two conditions, but in selective manners: (1) Learning of other sequences during the retention period interfered with accuracy, but not speed, of performance; (2) Inter-manual transfer was absent for speed, but not accuracy, of performance. The human subjects performed basically the same task as the monkeys. Each subject initially learned one sequence of 20 button presses by trial-and-error during an 8-10 day learning session. After 16 months, they were asked to perform the previously learned sequence (OLD sequence) and additional sequences including RECENT sequences (learned one day before) and NEW sequences. Their performance was considerably better on OLD and RECENT sequences than NEW sequences. Whereas the number of errors (reflecting 'accuracy') was lower for RECENT than for OLD sequences, the performance time (reflecting 'speed') was shorter for OLD than for RECENT sequences. Interestingly, the subjects were unaware that they had experienced OLD sequences. The results suggest that a motor skill is acquired and retained in two different forms, accuracy and speed. This occurs separately but concurrently. This conclusion is consistent with the hypothesis that at least two neural mechanisms operate independently to represent a motor skill.

Transporter gene expression in lactating and nonlactating human mammary epithelial cells using real-time reverse transcription-polymerase chain reaction

Transporter-mediated processes in the lactating mammary gland may explain the significant accumulation of certain drugs in breast milk. The purpose of this study was to identify potential candidate drug transport proteins involved in drug accumulation in milk. Quantitative reverse transcription-polymerase chain reaction methods were developed to determine the relative RNA levels of 30 different drug transporter genes. Transporter gene RNA levels in lactating mammary epithelial cells (MEC) purified from pooled fresh breast milk samples were compared with levels in nonlactating MEC, liver, and kidney tissue. Transcripts were detected in lactating MEC for OCT1, OCT3, OCTN1, OCTN2, OATP-A, OATP-B, OATP-D, OATP-E, MRP1, MRP2, MRP5, MDR1, CNT1, CNT3, ENT1, ENT3, NCBT1, PEPT1, and PEPT2. No transcripts were detected for OCT2, OAT1, OAT2, OAT3, OAT4, OATP-C, MRP3, MRP4, CNT2, ENT2, and NCBT2. Lactating MEC demonstrated more than 4-fold higher RNA levels of OCT1, OCTN1, PEPT2, CNT1, CNT3, and ENT3, and more than 4-fold lower RNA levels of MDR1 and OCTN2 relative to nonlactating MEC. Lactating MEC showed significantly higher RNA levels of CNT3 relative to liver and kidney, increased PEPT2 RNA levels relative to liver, and increased OATP-A RNA levels relative to kidney. These data imply CNT3 may play a specialized role in nucleoside accumulation in milk and may identify an important role for PEPT2 and OATP-A transporters at the lactating mammary epithelium. Furthermore, transporters expressed in lactating MEC identify a potential role for these transporters in drug disposition at the mammary gland.

Effects of delay time on transient Ni-like x-ray lasers

In transient collisional excitation scheme, a long (nanosecond) prepulse is used to perform and ionize plasmas. After a delay time, a short (sub- or picosecond) intense laser pulse is used to rapidly heat the plasma. This results in transient x-ray lasers with high gain. Effects of delay time on transient collisional excitation nickel-like x-ray lasers are investigated analytically using a simple model. The calculations show that the longer delay time can greatly relax the density gradient. This is very critical for the propagation of x-ray lasers. However, a too long delay will reduce the electron temperature of the plasma before the arrival of the short pulse. Increasing the intensity of the long pulse or extending the pulse duration can keep the temperature required to maintain a high percentage of Ni-like ions while the delay time is longer. Similarly, increasing the intensity of the short pulse or extending the duration can also raise the electron temperature, resulting in higher gain coefficient. Our results indicate that extending the pulse duration is more efficient than that of increasing the intensity.

[Analysis of complications and deaths in aged patients with obstructive jaundice]

The reasons of complications and deaths in 98 aged patients with obstructive jaundice were analysed in the paper. Among them, 52 cases were diagnosed as benign obstruction, 46 cases as malignant obstruction; 92 patients were treated by surgical management(15 died), 6 patients were treated without operation(4 died). The results showed that effective management on time and intensive perioperative care are important to minimize the mortality rate. Malignant obstructive jaundice was more harmful to the patients' renal function no the mortality rate would be increased. The operations, internal drainage and pressure reduction of biliary duct, were performed on time, thus the survival rate was improve.

Localization, genomic organization, and alternative transcription of a novel human SAM-dependent methyltransferase gene on chromosome 2p22-->p21

As part of our studies to identify the gene responsible for hereditary gingival fibromatosis, GINGF (OMIM 135300), we have identified and cloned a novel human gene that contains the highly conserved methyltransferase domain characteristic of S-adenosylmethionine-dependent methyltransferases. We localized this gene (C2orf8 encoding 288L6 SAM-methyltransferase) to chromosome 2p22-->p21 by FISH, and sublocalized it to BAC RP11 288L6 flanked by D2S2238 and D2S2331. Computational analysis of aligned ESTs identified ten exons in the hypothetical C2orf8 gene. Results of RACE analyses in placenta identified multiple transcripts of this gene with heterogeneity at the 5'-UTR. Alternative transcription and tissue specific expression of C2orf8 were detected by RT-PCR and Northern blot analyses. C2orf8 is expressed in a variety of tissues including brain, colon, gingiva, heart, kidney, liver, lung, placenta, small intestine, spleen, and thymus. Open reading frame analysis of the alternative transcripts identified a shared coding region spanning exons 6-10. This ORF consists of 732 nucleotides encoding a putative 244 amino acid protein. Bioinformational searches of both C2orf8 and the putative protein product identified three methyltransferase motifs conserved across many prokaryotic and eukaryotic species. Sequence analyses of C2orf8 excluded coding region mutations as causative of GINGF.

Investigations on a clinically and functionally unusual and novel germline p53 mutation

This report describes an individual with a rare choroid plexus papilloma in adulthood (age 29) after earlier having an osteosarcoma (age 22). The results from this study, and others, suggest that it may be advisable to consider the possibility of a germline p53 mutation in adults presenting with choroid plexus tumours. In the current study automated DNA sequencing of genomic DNA detected a novel germline 7 base pair insertion in exon 5 of the p53 gene in this patient. The alteration in frame would produce amino acid substitutions beginning with alanine to glycine at position 161 and a stop codon at position 182 in the mutated protein. Surprisingly two assays of p53 function gave apparently wild-type results on peripheral blood lymphocytes from this individual. These results led us to carry out more detailed functional tests on the mutant protein. The mutant allele was expressed either at very low levels or not at all in phytohaemagglutinin stimulated lymphocytes. Further, the mutant protein was completely non-functional in terms of its ability to transactivate a series of p53-responsive genes (p21(WAF1), bax, PIG3), to transrepress a target gene and to inhibit colony growth in transfected Saos-2 cells. However, surprisingly, data from irradiated peripheral blood lymphocytes and transfected Saos-2 cells, suggested that this truncated, mutant protein retains significant ability to induce apoptosis.

Effect of dimethoate on the function and expression of nicotinic acetylcholine receptor in primary skeletal muscle cell culture

To investigate the molecular mechanism of intermediate myasthenia syndrome (IMS), we analyzed the toxic effects of the representative organophosphate dimethoate on the function and expression of the nicotinic acetylcholine receptor (nAChR) in primary skeletal muscle cell culture. The results showed that the expression of nAChR on the muscle cell membrane was significantly increased after cells were exposed to dimethoate (130 microM). AChR function measured by carbachol-induced (22)Na+ influx demonstrated that dimethoate may inhibit the nAChR function either by binding to a noncompetitive site and changing the conformational state of nAChR or by blocking the nAChR channel directly. This study also demonstrated that dimethoate could rapidly induce the expression of c-fos, with a maximal effect at about 40 min, and c-fos might act as a transcriptional factor in regulating the expression of nAChR in the primary skeletal muscle cell culture following organophosphate exposure.

Proposal of a novel parameter to describe the influence of pH on the lag phase of Listeria monocytogenes

Predictive models for lag phase duration (lambda) have been less reliable than specific growth rate (mu) models due, in part, to the influence of the pre-growth environment on lambda. A discrete modelling approach was taken to more completely define the response of individual cells to new environments. Time to detection (td) data was obtained from serial twofold dilutions of Listeria monocytogenes growing in a Bioscreen at 30 degrees C. Comparison of the inoculum densities required to achieve maximum td at growth pH values from 7.2 to 4.7 revealed that, as the growth pH decreased, fewer cells were capable of making the transition to the exponential phase. The proportion of these cells (termed "adaptable cells") in the original inoculum was used to define a new parameter (r0) which, when combined with the constant mean individual cell physiological state parameter (p0), the variation in p0 (SDp0), the inital inoculum (N0) and the maximum population density (Nmax) was able to simulate a complete growth curve. Power transformations with rescaled explanatory variables provided suitable models for the influence of pH on mu, r0, and SDp0, (r2>0.70).