Construction and identification of recombinant adenovirus vector containing the hVEGF165 gene

To construct the recombinant adenovirus vector containing the cDNA for human vascular endothelial growth factor (hVEGF165), the cDNA for hVEGF165 was subcloned into pACCMV.pLpA. Subsequently, this recombinant pACCMV.hVEGF was co-transfected into 293 cells together with pJM17 to obtain the replication-deficient recombinant adenovirus containing hVEGF gene--AdCMV.hVEGF. The VEGF gene expression was detected by using RT-PCR and Western blot in rabbit aorta vascular smooth muscle cells (VSMC) infected with AdCMV.hVEGF. Cultured human umbilical vein endothelial cells (HUVEC) were incubated with the conditioned medium (CM) from above mentioned VSMC infected with AdCMV.hVEGF to observe the effect of VEGF on proliferation of HUVEC. 48 h after the infection with AdCMV.hVEGF, VSMC demonstrated VEGF expression, and the expressed VEGF could stimulate the proliferation of HUVEC in vitro. Successfully prepared AdCMV.hVEGF165 could express biologically active VEGF in infected VSMC, and stimulate proliferation of HUVEC.

Effects of saccular otolith removal on hearing sensitivity of the sleeper goby (Dormitator latifrons)

It is not known to what extent the entire saccule contributes to overall hearing sensitivity in any fish species. Here we report directional and frequency sensitivity in a teleost fish (Dormitator latifrons) and effects of unilateral and bilateral removal of saccular otoliths on its hearing sensitivity. The fish had different hearing thresholds in the horizontal (-54.4 to -50.3 dB re: 1 micro m) and mid-sagittal (-58.6 to -53.1 dB) planes. At 100 Hz, unilateral otolith removal did not significantly change hearing sensitivity in the mid-sagittal plane, but caused selective reductions of auditory sensitivity by 3-7 dB in the azimuthal axes that are consistent with the longitudinal axis of the damaged saccule. Along the fish's longitudinal axis, unilateral otolith removal significantly decreased auditory sensitivity at 50 Hz and 400 Hz, but not at 100 Hz, 200 Hz, and 345 Hz. At 100 Hz, bilateral otolith removal resulted in robust hearing loss of 27-35 dB at different axes in both horizontal and mid-sagittal planes. Along the fish's longitudinal axis, the bilateral removal reduced auditory sensitivity by 13-27 dB at the different frequencies. Therefore, these results demonstrate that the saccule plays important roles in directional hearing and frequency responses.

The genomes of sheeppox and goatpox viruses

Sheeppox virus (SPPV) and goatpox virus (GTPV), members of the Capripoxvirus genus of the Poxviridae, are etiologic agents of important diseases of sheep and goats in northern and central Africa, southwest and central Asia, and the Indian subcontinent. Here we report the genomic sequence and comparative analysis of five SPPV and GTPV isolates, including three pathogenic field isolates and two attenuated vaccine viruses. SPPV and GTPV genomes are approximately 150 kbp and are strikingly similar to each other, exhibiting 96% nucleotide identity over their entire length. Wild-type genomes share at least 147 putative genes, including conserved poxvirus replicative and structural genes and genes likely involved in virulence and host range. SPPV and GTPV genomes are very similar to that of lumpy skin disease virus (LSDV), sharing 97% nucleotide identity. All SPPV and GTPV genes are present in LSDV. Notably in both SPPV and GTPV genomes, nine LSDV genes with likely virulence and host range functions are disrupted, including a gene unique to LSDV (LSDV132) and genes similar to those coding for interleukin-1 receptor, myxoma virus M003.2 and M004.1 genes (two copies each), and vaccinia virus F11L, N2L, and K7L genes. The absence of these genes in SPPV and GTPV suggests a significant role for them in the bovine host range. SPPV and GTPV genomes contain specific nucleotide differences, suggesting they are phylogenetically distinct. Relatively few genomic changes in SPPV and GTPV vaccine viruses account for viral attenuation, because they contain 71 and 7 genomic changes compared to their respective field strains. Notable genetic changes include mutation or disruption of genes with predicted functions involving virulence and host range, including two ankyrin repeat proteins in SPPV and three kelch-like proteins in GTPV. These comparative genomic data indicate the close genetic relationship among capripoxviruses, and they suggest that SPPV and GTPV are distinct and likely derived from an LSDV-like ancestor.

Novel swine virulence determinant in the left variable region of the African swine fever virus genome

Previously we have shown that the African swine fever virus (ASFV) NL gene deletion mutant E70DeltaNL is attenuated in pigs. Our recent observations that NL gene deletion mutants of two additional pathogenic ASFV isolates, Malawi Lil-20/1 and Pr4, remained highly virulent in swine (100% mortality) suggested that these isolates encoded an additional virulence determinant(s) that was absent from E70. To map this putative virulence determinant, in vivo marker rescue experiments were performed by inoculating swine with infection-transfection lysates containing E70 NL deletion mutant virus (E70DeltaNL) and cosmid DNA clones from the Malawi NL gene deletion mutant (MalDeltaNL). A cosmid clone representing the left-hand 38-kb region (map units 0.05 to 0.26) of the MalDeltaNL genome was capable of restoring full virulence to E70DeltaNL. Southern blot analysis of recovered virulent viruses confirmed that they were recombinant E70DeltaNL genomes containing a 23- to 28-kb DNA fragment of the Malawi genome. These recombinants exhibited an unaltered MalDeltaNL disease and virulence phenotype when inoculated into swine. Additional in vivo marker rescue experiments identified a 20-kb fragment, encoding members of multigene families (MGF) 360 and 530, as being capable of fully restoring virulence to E70DeltaNL. Comparative nucleotide sequence analysis of the left variable region of the E70DeltaNL and Malawi Lil-20/1 genomes identified an 8-kb deletion in the E70DeltaNL isolate which resulted in the deletion and/or truncation of three MGF 360 genes and four MGF 530 genes. A recombinant MalDeltaNL deletion mutant lacking three members of each MGF gene family was constructed and evaluated for virulence in swine. The mutant virus replicated normally in macrophage cell culture but was avirulent in swine. Together, these results indicate that a region within the left variable region of the ASFV genome containing the MGF 360 and 530 genes represents a previously unrecognized virulence determinant for domestic swine.

The genome of camelpox virus

Camelpox virus (CMLV), a member of the Orthopoxvirus genus in the Poxviridae, is the etiologic agent of a disease of camels. Here we report the CMLV genomic sequence with analysis. The 205,719-bp CMLV genome contains 211 putative genes and consists of a central region bound by identical inverted terminal repeats of approximately 7 kb. A high degree of similarity in gene order, gene content, and amino acid composition in the region located between CMLV017 and CMLV184 (average 96% amino acid identity to vaccinia virus (VACV)) indicates a close structural and functional relationship between CMLV and other known orthopoxviruses (OPVs). Notably, CMLV contains a unique region of approximately 3 kb, which encodes three ORFs (CMLV185, CMLV186, CMLV187) absent in other OPVs. These ORFs are most similar to B22R homologues found in other chordopoxvirus genera. Among OPVs, CMLV is the most closely related to variola virus (VARV), sharing all genes involved in basic replicative functions and the majority of genes involved in other host-related functions. Differences between CMLV and VARV include deletion and disruption of a large number of genes. Twenty-seven CMLV ORFs are absent in VARV, including seven full-length homologues of NMDA-like receptor, phospholipase D, Schlafen, MT-4 virulence, kelch, VACV C8L, and cowpox (CPXV) B21R proteins. Thirty-eight CMLV ORFs, some of which are fragments of larger genes, differ in size from corresponding VARV ORFs by more than 10% (amino acids). Genome structure and phylogenetic analysis of DNA sequences for all ORFs indicate that CMLV is clearly distinct from VARV and VACV and, as it has been suggested for VARV, it may have originated from a CPXV virus-like ancestor.

Fundamental study on non-invasive blood glucose sensing

Diabetes is a disease which severely threatens the health of human beings. Unfortunately, current monitoring techniques with finger sticks discourage the regular use. Noninvasive spectroscopic measurement of blood glucose is a simple and painless technique, and reduces the long-term health care costs of diabetic patients due to no reagents. It is suitable for home use. Moreover, the establishment of the methodology not only applies to blood glucose noninvasive measurement, but also can be extended to noninvasive measurement of other analytes in body fluid, which will be of important significance for the development of the technique of clinical analysis. In this paper, some fundamental researches, which have been achieved in our laboratory in the field of non-invasive blood glucose measurement, were introduced. 1. Fundamental research was done for the glucose concentrations from simple to complex samples with near and middle infrared spectroscopy: (1) the relationship between the instrument precision and prediction accuracy of the glucose measurement; (2) the change of the result of the quantitative measurement with the change of the complexity of samples; (3) the attempt of increasing the prediction accuracy of the glucose measurement by improving the methods of modeling. The research results showed that it is feasible for non-invasive blood glucose measurement with near and middle infrared spectroscopy in theory, and the experimental results, from simple to complex samples, proved that it is effective for the methodology consisting of hardware and software. 2. According to the characteristics of human body measurement, the effects of measuring conditions on measurement results, such as: (1) the effect of measurement position; (2) the effect of measurement pressure; (3) the effect of measurement site; (4) the effect of measured individual, were investigated. With the fundamental researches, the special problems of human body measurement were solved. In addition, the practical and effective method of noninvasive human blood glucose measurement was proposed.

The genome of swinepox virus

Swinepox virus (SWPV), the sole member of the Suipoxvirus genus of the Poxviridae, is the etiologic agent of a worldwide disease specific for swine. Here we report the genomic sequence of SWPV. The 146-kbp SWPV genome consists of a central coding region bounded by identical 3.7-kbp inverted terminal repeats and contains 150 putative genes. Comparison of SWPV with chordopoxviruses reveals 146 conserved genes encoding proteins involved in basic replicative functions, viral virulence, host range, and immune evasion. Notably, these include genes with similarity to genes for gamma interferon (IFN-gamma) receptor, IFN resistance protein, interleukin-18 binding protein, IFN-alpha/beta binding protein, extracellular enveloped virus host range protein, dUTPase, hydroxysteroid dehydrogenase, superoxide dismutase, serpin, herpesvirus major histocompatibility complex inhibitor, ectromelia virus macrophage host range protein, myxoma virus M011L, variola virus B22R, four ankyrin repeat proteins, three kelch-like proteins, five vaccinia virus (VV) A52R-like family proteins, and two G protein-coupled receptors. The most conserved genomic region is centrally located and corresponds to the VV region located between genes F9L and A38L. Within the terminal 13 kbp, colinearity is disrupted and multiple poxvirus gene homologues are absent or share a lower percentage of amino acid identity. Most of these differences involve genes and gene families with likely functions involving viral virulence and host range. Three open reading frames (SPV018, SPV019. and SPV020) are unique for SWPV. Phylogenetic analysis, genome organization, and amino acid identity indicate that SWPV is most closely related to the capripoxvirus lumpy skin disease virus, followed by the yatapoxvirus yaba-like disease virus and the leporipoxviruses. The gene complement of SWPV better defines Suipoxvirus within the Chordopoxvirinae subfamily and provides a basis for future genetic comparisons.

Transformation of cells overexpressing a tyrosine kinase by phospholipase D1 and D2

Phospholipase D (PLD) activity is elevated in response to most mitogenic signals. Two mammalian PLD genes (PLD1 and PLD2) have been cloned and their gene products have been characterized. PLD1 is a downstream target of the Ras/RalA GTPase cascade implicated in mitogenic and oncogenic signaling. Consistent with a role in mitogenic signaling, elevated expression of PLD1 transforms cells overexpressing the epidermal growth factor (EGF) receptor (EGFR). However, PLD2 colocalizes with the EGFR in caveolin-enriched light membrane microdomains. We therefore investigated whether PLD2 could also contribute to the transformation of cells overexpressing a tyrosine kinase. We report here that elevated expression of PLD2 transforms rat fibroblasts overexpressing either the EGFR or c-Src. Since overexpression of a tyrosine kinase is a common genetic alteration in several human cancers, these data suggest that elevation of either PLD1 or PLD2 may contribute to the progression to a malignant phenotype in cells with elevated tyrosine kinase activity.

Study of adaptive mutations in Salmonella typhimurium by using a super-repressing mutant of a trans regulatory gene purR

Salmonella typhimurium purR encodes a transcriptional repressor regulating gene expression of de novo purine nucleotide biosynthesis. It represses purD gene transcription by binding to the 16-base pair purD operator (PUR box). A S. typhimurium strain carrying a super-repressing mutant of purR, purR(s), has been used as an experimental system to study adaptive mutation. Escherichia coli lac genes were genetically engineered into S. typhimurium chromosome and repressed by purR(s) so that they could be used as an indicator of adaptive mutations in purR(s) or in the purD operator. Mutations in purR(s) or in the purD operator accumulated when the mutant strain was placed on a minimal lactose plate supplemented with 10 microg/ml of adenine during prolonged incubation. These specific mutations reverted the mutant strain from lac(-) to lac(+) phenotype. The lac(+) strains were categorized into the early- and late-arising mutants according to the time for colony appearance. Our genetic studies indicate that (i) Poisson distributed mutations accumulated in the chromosomal regulatory gene purR or the purD operator in very slowly dividing cells under selection; (ii) after about 8 days of selection, the frequency of mutations in purD operator reached the high value of about two mutations per 10(8) cells; (iii) the mutational spectrum in the purD operator during growth was not significantly different from that during selection; (iv) defects in mutL or mutS appeared to have a stronger effect on growth-dependent mutations than on adaptive mutations.

Phylogenetic comparison of classical swine fever virus in China

An N-terminal fragment of the E2 gene of classical swine fever (CSF) virus encoding major immunogenic sites was amplified by RT-PCR directly from 110 clinical specimens representing 109 epizootic sites during the last decade in China. Phylogenetic relationships between these viruses as well as 20 reference strains were determined by comparison of their nucleotide sequences. A phylogenetic tree showed that 103 of the 110 field viruses (93.6%) were clustered within group 2 and subdivided into three subgroups, while the remaining seven viruses (6.4%), along with two Chinese reference strains, Shimen and HCLV (attenuated vaccine strain), were clustered into subgroup 1.1 within group 1. However, none of the Chinese CSF viruses were members of subgroup 1.2 (represented by reference strain Brescia). This is the first report on the distribution of CSF virus genotypes in China. Results indicated that CSF viruses predominating in recent epizootics within China are genetically divergent from the reference strain Shimen and the vaccine strain HCLV.

[Detection of the expression of Smad4, transforming growth factor beta(1) and beta receptor II proteins in paraffin-embedded human pancreatic cancer tissues]

OBJECTIVE

To explore the relationships between Smad4, TGF beta1 and TbetaR II in the TGF-beta pathway and the possible mechanisms by which they effect pancreatic carcinoma.

METHODS

The expression of Smad4, TGF beta1 and TbetaR II in paraffin embedded pancreatic carcinoma tissues was detected by using antibodies against Smad4, TGF beta1 and TbetaR II with EnVision immunohistochemistry.

RESULTS

The positive rates of Smad4, TGF beta1 and TbetaR II were 58.93% (33), 66.07% (37) and 60.71% (34), respectively. The positive rates of the above three proteins in matched normal pancreatic tissues were 89.29% (50), 25.00% (14) and 25.00% (14) respectively. There was a significant relationship between the expression of TGF beta1, clinical stage and the metastasis of the tumor (P < 0.05). There was also a significant relationship between the expressions of TGF beta1 and TbetaR II (P < 0.05).

CONCLUSIONS

The expression of Smad4 in pancreatic carcinoma tissue is significantly decreased but the expression of TGF beta1 and TbetaR II are increased. Smad4 may play an important role in the regulation of TGFbeta inducible gene expression and subsequent growth inhibition, but TGFbeta may also act in a Smad4-independent manner.

Treatment of vitamin D deficiency due to Crohn's disease with tanning bed ultraviolet B radiation

In Crohn's disease, severe skeletal demineralization, secondary hyperparathyroidism, and muscle weakness can occur. This may be caused by impaired vitamin D absorption, resulting from extensive intestinal disease and resection of duodenum and jejunum, where vitamin D is absorbed. We report a 57-year-old woman with a long history of Crohn's disease and short-bowel syndrome who had only 2 feet of small intestine remaining after 3 bowel resections. She was taking a daily multivitamin containing 400 IU of vitamin D(3) and was dependent on total parenteral nutrition that contained 200 IU of vitamin D and calcium (18 mEq in a 1-L bag infused over 8 hours daily) for a period of 36 months. Despite the above replacement, she complained of bone pain and muscle weakness, and she continued to be vitamin D-deficient with a 25(OH)D level <20 ng/mL. She was then exposed to ultraviolet B (UVB) radiation in a tanning bed wearing a 1-piece bathing suit for 10 minutes, 3 times a week for 6 months at the General Clinical Research Center, Boston University Medical Center. She tolerated the irradiation well without evidence of erythema. After 4 weeks, her serum 25(OH)D level increased by 357% from 7 to 32 ng/mL, parathyroid hormone level decreased by 52% from 92 to 44 pg/mL, and the serum calcium level increased from 7.8 to 8.5 mg/dL. After 6 months of UVB treatment, her serum 25(OH)D level was maintained in the normal range and was free of muscle weakness, and bone and muscle pain.

[Diagnosis and treatment of primary intracranial lymphoma]

OBJECTIVE

To discuss the clinical characteristics, diagnosis, and treatment of primary intracranial lymphoma.

METHODS

A total of 148 cases of primary intracranial lymphoma from January 1984 to January 2000 were reviewed in our study.

RESULTS

Among the 148 cases, total and subtotal removal was achieved in 117 cases, partial removal in 31 cases. All the cases were treated by the radiotherapy after surgery. 44 cases combined with chemotherapy. The symptoms of patients in 112 cases (76%) were relieved and 36 cases (24%) progressed with 8 cases dead after surgery.

CONCLUSION

Primary intracranial lymphoma is a malignant neoplasm. The main treatment is surgical removal combining with postoperative radiotherapy. Prognosis is poor.

The change and significance of the Na+-K+-ATPase alpha-subunit in ouabain-hypertensive rats

Ouabain has recently been identified as an endogenous Na+-K+ pump inhibitor having a close association with hypertension. However, some patients with hypertention do not show high levels of endogenous ouabain (EO), and patients with high EO levels do not necessarily suffer from hypertention. It is believed that the Na+-K+-ATPase activity in essential hypertension does not undergo homogenous change. The present study was designed, therefore, to investigate the expression and the significance of the Na+-K+-ATPase alpha-subunit isoforms in kidney tissue in ouabain-hypertensive rats. Ouabain was administered chronically to establish a model of ouabain-hypertensive rats. Biochemical analysis, cytobiology and sABC immunohistochemistry were they used to assay for expression of Na+-K+-ATPase alpha-subunit isoforms in kidney tissue. After the first week of receiving ouabain, 65% (n=13) of rats had hypertension. After the second week, the blood pressure of these 13 hypertensive rats was increased significantly compared to the baseline and control levels (p<0.05). The plasma renin activity was normal, and angiotensin II and aldosterone levels were increased significantly in these rats (p<0.05). But in the other 35% (n=7) of rats of the experimental group, there was no apparent increase in blood pressure after receiving ouabain. The plasma ouabain level in the non-hypertensive subgroup was significantly higher than that in the hypertensive subgroup, but the 86Rb intake and the number of 3H-ouabain binding sites did not decrease. The Na+-K+-ATPase activity showed non-homogeneous changes. In hypertensive rats, the expression levels of ouabain paralleled the degree of hypertension (r=0.88, p<0.05). The positive granules were mainly scattered in the cytoblastoma of the reticular zone of adrenal cortex. There were thus different levels of expression of Na+-K+-ATPase alpha-subunit isoforms in this model. In the hypertension subgroup the alpha1 was most strongly expressed, followed by the alpha2 and alpha3 isforms. But in the non-hypertensive subgroup the order was alpha3 > alpha2 > alpha1. The positive granular was mainly scattered in the convoluted tubules of the kidney. These results suggest that the high level of ouabain and the change of the Na+-K+-ATPase alpha-subunit isoforms may play a critical role in hypertension.

Synthesis of griseolic acid B by pi-face-dependent radical cyclization

[reaction: see text]. Radical cyclization of 6 affords the bicyclic vinyl ether 9 with the appropriate stereochemistry for elaboration (seven steps) to griseolic acid B (1).

Genome sequence of a baculovirus pathogenic for Culex nigripalpus

In this report we describe the complete genome sequence of a nucleopolyhedrovirus that infects larval stages of the mosquito Culex nigripalpus (CuniNPV). The CuniNPV genome is a circular double-stranded DNA molecule of 108,252 bp and is predicted to contain 109 genes. Although 36 of these genes show homology to genes from other baculoviruses, their orientation and order exhibit little conservation relative to the genomes of lepidopteran baculoviruses. CuniNPV genes homologous to those from other baculoviruses include genes involved in early and late gene expression (lef-4, lef-5, lef-8, lef-9, vlf-1, and p47), DNA replication (lef-1, lef-2, helicase-1, and dna-pol), and structural functions (vp39, vp91, odv-ec27, odv-e56, p6.9, gp41, p74, and vp1054). Auxiliary genes include homologues of genes encoding the p35 antiapoptosis protein and a novel insulin binding-related protein. In contrast to these conserved genes, CuniNPV lacks apparent homologues of baculovirus genes essential (ie-1 and lef-3) or stimulatory (ie-2, lef-7, pe38) for DNA replication. Also, baculovirus genes essential or stimulatory for early-late (ie-1, ie-2), early (ie-0 and pe-38), and late (lef-6, lef-11, and pp31) gene transcription are not identifiable. In addition, CuniNPV lacks homologues of genes involved in the formation of virogenic stroma (pp31), nucleocapsid (orf1629, p87, and p24), envelope of occluded virions (odv-e25, odv-e66, odv-e18), and polyhedra (polyhedrin/granulin, p10, pp34, and fp25k). A homologue of gp64, a budded virus envelope fusion protein, was also absent, although a gene related to the other category of baculovirus budded virus envelope proteins, Ld130, was present. The absence of homologues of occlusion-derived virion (ODV) envelope proteins and occlusion body (OB) protein (polyhedrin) suggests that both CuniNPV ODV and OB may be structurally and compositionally different from those found in terrestrial lepidopteran hosts. The striking difference in genome organization, the low level of conservation of homologous genes, and the lack of many genes conserved in other baculoviruses suggest a large evolutionary distance between CuniNPV and lepidopteran baculoviruses.

[Fifty year's career of Chinese Journal of Medical History]

The Journal of Medical History, the antecedent of the now Chinese Journal of Medical History, was inaugurated in March 1947. This paper divides the whole course of publication and compilation of this Journal into 3 stages, namely, Stage of Initiation and Growth (1947-1948), Stage of Tortuous Progressing (1951-1959), Stage of Flourishing and developing (1980-). Altogether 25 volumes, 95 issues have been published in 953 millon Chinese characters and 1684 original articles. Being a highly effective major journal of medical history, this Journal satisfies nearly 40% of the information in this subject and has been indexed by major medical cataloging tool books, both domestic and foreign. Experience and prospects are also mentioned here.

Phosphorylation of tau by glycogen synthase kinase 3beta in intact mammalian cells influences the stability of microtubules

Tau is a neuronal microtubule-associated protein found predominantly in axons. Hyperphosphorylation of tau reduces the stability of microtubules, which may be a pathogenic mechanism in Alzheimer's disease. To understand the different effects between tau and glycogen synthase kinase 3beta (GSK-3beta) phosphorylated tau on the organization and stability of microtubules, we performed transfection studies on 3T3 cells using EGFP-tau (Enhanced Green Fluorescence Protein-tau) and GSK-3beta to quantify the stability of microtubules. Laser confocal microscope observation revealed that thick and thin microtubule bundles could be induced by tau and GSK-3beta phosphorylated tau. The bundles appeared either to be relatively straight or to form a ring around the circumference of the cell. Both the thick and thin microtubule bundles were resistant to colchicine-induced dissociation, with thick bundles more resistant than thin bundles. The bundles induced by GSK-3beta phosphorylated tau were sensitive to colchicine, and could be reversed by the addition of LiCl, an inhibitor of GSK-3beta.

Ion conduction pore is conserved among potassium channels

Potassium channels, a group of specialized membrane proteins, enable K+ ions to flow selectively across cell membranes. Transmembrane K+ currents underlie electrical signalling in neurons and other excitable cells. The atomic structure of a bacterial K+ channel pore has been solved by means of X-ray crystallography. To the extent that the prokaryotic pore is representative of other K+ channels, this landmark achievement has profound implications for our general understanding of K+ channels. But serious doubts have been raised concerning whether the prokaryotic K+ channel pore does actually represent those of eukaryotes. Here we have addressed this fundamental issue by substituting the prokaryotic pore into eukaryotic voltage-gated and inward-rectifier K+ channels. The resulting chimaeras retain the respective functional hallmarks of the eukaryotic channels, which indicates that the ion conduction pore is indeed conserved among K+ channels.

Bisphosphonate derivatized polyurethanes resist calcification

Calcification of polyurethane cardiovascular implants is an important disease process that has the potential to compromise the long-term function of devices such as polymer heart valves and ventricular assist systems. In this study we report the successful formulation and characterization of bisphosphonate-derivatized polyurethanes, hypothesized to resist implant calcification based on the pharmacologic activity of the immobilized bisphosphonate. Fully polymerized polyurethanes (a polyurea-polyurethane and a polycarbonate polyurethane) were modified (post-polymerization) with bromoalkylation of the hard segments followed by attachment of a bisphosphonate group at the bromine site. These bisphosphonate-polyurethanes resisted calcification in rat 60 day subdermal implants compared to nonmodified control polyurethane implants, that calcify. Bisphosphonates-modified polyurethanes were also studied in circulatory implants using a pulmonary valve cusp replacement model in sheep. Polyurethane cusps modified with bisphosphonate did not calcify in 90 day implants. compared to control polyurethane cusps implants, that demonstrated nodular surface oriented calcific deposits. It is concluded that bisphosphonate modified polyurethanes resist calcification both in subdermal implants and in the circulation. This novel biomaterial approach offers great promise for long-term blood stream implantation with calcification resistance.

Effects of ouabain and digoxin on gene expression of sodium pump alpha-subunit isoforms in rat myocardium

OBJECTIVE

To compare the effects of ouabain and digoxin on the gene expression of sodium pump alpha-subunit isoforms in the myocardium of rats.

METHODS

Normal Sprague-Dawley (SD) rats were injected with ouabain (20 micrograms.kg-1.d-1, i.p.), digoxin (32 micrograms.kg-1.d-1, i.p.) and normal saline (NS) once a day, respectively, and indirect systolic blood pressure was recorded once a week. Six weeks later, all of the rats were killed, and sodium pump alpha 1-, alpha 2-, and alpha 3-subunit mRNA levels in the myocardium were detected with the reverse transcription polymerase chain reaction (RT-PCR) method.

RESULTS

The systolic blood pressure of the rats infused with ouabain increased significantly at the end of week 6 (132.6 +/- 9.0 mm Hg vs 115.7 +/- 8.2 mm Hg, P < 0.01), while no difference in blood pressure was found between the digoxin group and the NS group. The expression of sodium pump alpha-subunit isoforms in the ventricular myocardium was regulated by either ouabain or digoxin. Both ouabain and digoxin stimulated expression of the alpha 3-isoform, whereas alpha 2 was unchanged in those two groups. alpha 1-isoform expression decreased in the ouabain group and was unchanged in the digoxin group.

CONCLUSIONS

These results suggest that both ouabain and digoxin could regulate sodium pump alpha-subunit isoform expression, which might be related to the physiological roles of endogenous ouabain and might be responsible for the difference in the pharmacological and toxicological effects of ouabain and digoxin, including their effects on blood pressure.