Genetic analysis of recent Taiwanese isolates of a variant of coxsackievirus A24

Epidemics of acute hemorrhagic conjunctivitis (AHC) caused by a variant of coxsackievirus A24 (CA24v) reappeared in Taiwan in 1990 and 1994, following the first two epidemics of 1985--86 and 1988--89. To analyze the genetic diversity of recent CA24v in Taiwan, 7 Taiwanese strains isolated during the 1990--94 period were studied together with one Japanese and two Thai strains isolated in 1993. A fragment of 674 nucleotides between the carboxy terminal 3A and the amino terminal 3D polymerase, including the entire 3C protease (3C(pro)), was amplified by a reverse transcription-polymerase chain reaction (RT-PCR) and the nucleotide sequences were determined. In the 549 nucleotides (183 amino acids) of the entire 3C(pro), we found nucleotide differences at 80 positions between 10 strains and the prototype strain, EH24/70, one of the earliest strains of CA24v. Most of the nucleotide changes were synonymous substitutions and only nine amino acid changes were found. The nucleotide sequence homologies among 71 strains worldwide were 88-100%. These 71 nucleotide sequences were then analyzed by Neighbor-joining method and phylogenetically separated into three distinct genotypes. Genotype I consisted of early strains isolated in 1970--71 from Singapore and Hong Kong. Genotype II included isolates from Singapore and Thailand obtained in 1975. Genotype III comprised strains from the eastern hemisphere isolated in 1985--94 from Japan, Taiwan, China, Hong Kong, Thailand, Singapore, Pakistan and Ghana. They were further divided chronologically into six clusters. The recent isolates from Taiwan obtained in 1985/1986, 1988/1989 and 1990--94 were classified into genotype III Clusters 1, 5, and 6 respectively. The evolutionary rate was re-estimated to be 3 x 10(- 3) 30 years after the emergence of the virus.

Guided bone regeneration using bone grafts and collagen membranes

When nonabsorbable membranes are used for guided bone regeneration (GBR), second surgeries are required for membrane retrieval. In addition, these types of membranes show a high incidence of flap sloughing and membrane exposure that often lead to infection and unfavorable results. Absorbable barriers such as collagen membranes were developed to overcome these drawbacks. This article presents the principles and the clinical procedure of using barrier membranes composed of absorbable collagen in GBR aimed at the repair and regeneration of ridge dehiscence defects around implants. The unique properties of collagen membranes that make them ideally suited to GBR procedures are reviewed. In addition, the indications and contraindications for using collagen membranes for GBR procedures are examined. Finally, cases are presented to demonstrate details of surgical principles and techniques.

Neurotensin excitation of serotonergic neurons in the rat nucleus raphe magnus: ionic and molecular mechanisms

To understand the cellular and molecular mechanisms by which neurotensin (NT) induces an analgesic effect in the nucleus raphe magnus (NRM), whole-cell patch-clamp recordings were performed to investigate the electrophysiological effects of NT on acutely dissociated NRM neurons. Two subtypes of neurons, primary serotonergic and secondary non-serotonergic cells, were identified from acutely isolated NRM neurons. During current-clamp recordings, NT depolarized NRM serotonergic neurons and evoked action potentials. Voltage-clamp recordings showed that NT excited serotonergic neurons by enhancing a voltage-insensitive and non-selective cationic conductance. Both SR48692, a selective antagonist of subtype 1 neurotensin receptor (NTR-1), and SR 142948A, a non-selective antagonist of NTR-1 and subtype 2 neurotensin receptor (NTR-2), failed to prevent neurotensin from exciting NRM serotonergic neurons. NT-evoked cationic current was inhibited by the intracellular administration of GDP-beta-S. NT failed to induce cationic currents after dialyzing serotonergic neurons with the anti-G(alphaq/11) antibody. Cellular Ca(2+) imaging study using fura-2 showed that NT induced the calcium release from the intracellular store. NT-evoked current was blocked after the internal perfusion of heparin, an IP(3) receptor antagonist, or BAPTA, a fast Ca(2+) chelator. It is concluded that neurotensin enhancement of the cationic conductance of NRM serotonergic neurons is mediated by a novel subtype of neurotensin receptors. The coupling mechanism via G(alphaq/11) proteins is likely to involve the generation of IP(3), and subsequent IP(3)-evoked Ca(2+) release from intracellular stores results in activating the non-selective cationic conductance.

Neurotensin excites periaqueductal gray neurons projecting to the rostral ventromedial medulla

Microinjection of neurotensin into the midbrain periaqueductal gray (PAG) produces a potent and naloxone-insensitive analgesic effect. To test the hypothesis that neurotensin induces the analgesic effect by activating the PAG-rostral ventromedial medulla (RVM) descending antinociceptive pathway, PAG neurons that project to RVM (PAG-RVM) were identified by microinjecting DiI(C18), a retrograde tracing dye, into the rat RVM. Subsequently, fluorescently labeled PAG-RVM projection neurons were acutely dissociated and selected for whole cell patch-clamp recordings. During current-clamp recordings, neurotensin depolarized retrogradely labeled PAG-RVM neurons and evoked action potentials. Voltage-clamp recordings indicated that neurotensin excited PAG-RVM neurons by opening the voltage-insensitive and nonselective cation channels. Both SR 48692, a selective NTR-1 antagonist, and SR 142948A, a nonselective antagonist of NTR-1 and NTR-2, failed to prevent neurotensin from exciting PAG-RVM neurons. Neurotensin failed to evoke cationic currents after internally perfusing PAG-RVM projection neurons with GDP-beta-S or anti-G(alpha q/11) antiserum. Cellular Ca(2+) fluorescence measurement using fura-2 indicated that neurotensin rapidly induced Ca(2+) release from intracellular stores of PAG-RVM neurons. Neurotensin-evoked cationic currents were blocked by heparin, an IP(3) receptor antagonist, and 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), a fast chelator of Ca(2+). These results suggest that by activating a novel subtype of neurotensin receptors, neurotensin depolarizes and excites PAG-RVM projection neurons through enhancing Ca(2+)-dependent nonselective cationic conductance. The coupling mechanism via G(alpha q/11) proteins is likely to involve the production of IP(3), and subsequent IP(3)-evoked Ca(2+) release leads to the opening of nonselective cation channels.

G protein-coupled receptor kinase 2 mediates mu-opioid receptor desensitization in GABAergic neurons of the nucleus raphe magnus

Nucleus raphe magnus (NRM) sends the projection to spinal dorsal horn and inhibits nociceptive transmission. Analgesic effect produced by mu-opioid receptor agonists including morphine partially results from activating the NRM-spinal cord pathway. It is generally believed that mu-opioid receptor agonists disinhibit spinally projecting neurons of the NRM and produce analgesia by hyperpolarizing GABAergic interneurons. In the present study, whole-cell patch-clamp recordings combined with single-cell RT-PCR analysis were used to test the hypothesis that DAMGO ([D-Ala(2),N-methyl-Phe(4),Gly-ol(5)]enkephalin), a specific mu-opioid receptor agonist, selectively hyperpolarizes NRM neurons expressing mRNA of glutamate decarboxylase (GAD(67)). Homologous desensitization of mu-opioid receptors in NRM neurons could result in the development of morphine-induced tolerance. G protein-coupled receptor kinase (GRK) is believed to mediate mu-opioid receptor desensitization in vivo. Therefore, we also investigated the involvement of GRK in mediating homologous desensitization of DAMAMGO-induced electrophysiological effects on NRM neurons by using two experimental strategies. First, single-cell RT-PCR assay was used to study the expression of GRK2 and GRK3 mRNAs in individual DAMGO-responsive NRM neurons. Whole-cell recording was also performed with an internal solution containing the synthetic peptide, which corresponds to G(betagamma)-binding domain of GRK and inhibits G(betagamma) activation of GRK. Our results suggest that DAMGO selectively hyperpolarizes NRM GABAergic neurons by opening inwardly rectifying K(+) channels and that GRK2 mediates short-term homologous desensitization of mu-opioid receptors in NRM GABAergic neurons.

5-HT1B receptor augmented 5-HT vasoconstrictor response of pulmonary artery in monocrotaline-induced pulmonary hypertensive rats

AIM

To study the relationship between the vasoconstrictor effect to 5-hydroxytryptamine (5-HT) and the expression of 5-HT1B-and 5-HT1D)-receptors in pulmonary arteries (PA) from normal and pulmonary hypertensive (PHT) rats.

METHODS

Monocrotaline (MCT)-treated rats were used as a model for chronic PHT. Concentration-response curves of 5-HT induced pulmonary vasoconstriction were established and semiquantitative RT-PCR was performed to identify mRNA expression of 5-HT1B- and 5-HT1D-receptors in rat PA.

RESULTS

5-HT induced vasoconstrictor response of PA from MCT rats was enhanced (Emax) 50 % +/- 20 % vs control 38 % +/- 21 %, P < 0.05). A significantly higher level of 5 -HT1B receptor mRNA expression was detected in PA from MCT rats. The ratio of the PCR products of 5-HT1B receptor gene to those of beta-actin gene was much higher in MCT rats than that in control rats (0.43 +/- 0.14 vs control 0.27 +/- 0.15, P < 0.05).

CONCLUSION

5-HT1B receptor is involved in pulmonary vasoconstriction and the enhanced level of 5-HT1B receptor mRNA expression is closely related to the augmentation of 5-HT induced pulmonary vasoconstriction in PHT rats.

[Pharmacokinetic studies of 20(R)-ginsenoside RG3 in human volunteers]

AIM

To study the pharmacokinetics of 20 (R)-ginsenoside Rg3 (GRg3) in human.

METHODS

High-performance liquid chromatography-ultraviolet detection method was used in this study.

RESULTS

The pharmacokinetics of GRg3 in 14 healthy volunteers were investigated. After a single oral dose of 3.2 mg.kg-1 in 8 male volunteers, the plasma concentration-time course fitted well to a two-compartment open model, with the following pharmacokinetic parameters: Tmax(0.66 +/- 0.10) h, Cmax(16 +/- 6) ng.mL-1, T1/2 alpha(0.46 +/- 0.12) h, T1/2 beta(4.9 +/- 1.1) h, T1/2(Ka)(0.28 +/- 0.04) h, AUC0-infinity(77 +/- 26) ng.mL-1.h. No kinetic analysis was made after an oral dose of 0.8 mg.kg-1 GRg3 in 6 other volunteers because of the low concentration, but a good correlation between Cmax and dosage of the two groups was found.

CONCLUSION

The absorption of GRg3 was rapid in man, and its elimination was rapid after oral administration of ginsenoside Rg3. The pharmacokinetic results shows that it exhibited first order kinetic characteristics.

Efficient diagnosis of dengue infections using patients' peripheral blood leukocytes and serum/plasma

OBJECTIVE

Dengue fever has been one of the most important health problems in Taiwan since a large outbreak during 1987 and 1988. It is critically necessary to have a diagnostic approach that can detect early infections in an outbreak or even find infections existing in silent transmission of the disease.

METHODS

To develop an efficient diagnostic protocol, 105 plasma/serum and 35 peripheral blood leukocyte (PBL) specimens from the 1994 outbreak in southern Taiwan were collected for assessment by various diagnostic techniques in this study.

RESULTS

In acute blood samples, dengue viruses were isolated from 19.4% (14/72) and 33.3% (14/42) of reported and confirmed cases, respectively. Viral RNA in serum/plasma was detected from 20.0% (12/60) of acute samples, which was significantly higher than that from convalescent samples (3/44; 6.8%). However, viral RNA in PBLs, detected by reverse transcription polymerase chain reaction (PBL-RT-PCR), could be observed in 73.2% (19/26) and 66.7% (6/9) of acute and convalescent samples, respectively. The persistence of dengue viruses in PBLs was also evidenced by the presence of viral antigens in 42.9% (4/7) of confirmed convalescent samples by the immunofluorescence antibody test. In addition, IgM antibodies were detected in 43.8% (46/105) of reported cases and 85.2% (46/54) of confirmed cases by the IgM antibody capture enzyme-linked immunosorbent assay (MAC-ELISA).

CONCLUSIONS

Although IgM antibody detection achieved the highest detection rate among techniques assessed in this study, no individual test can actually reach full efficiency for early diagnosis of dengue infections. Here, we propose a protocol which applies MAC-ELISA and PBL-RT-PCR in sequence, by which 22 confirmed cases were definitely proved as dengue positive. High levels of both sensitivity and specificity were shown in this protocol.

Collagen membranes: a review

Collagen materials have been utilized in medicine and dentistry because of their proven biocompatability and capability of promoting wound healing. For guided tissue regeneration (GTR) procedures, collagen membranes have been shown to be comparable to non-absorbable membranes with regard to probing depth reduction, clinical attachment gain, and percent of bone fill. Although these membranes are absorbable, collagen membranes have been demonstrated to prevent epithelial down-growth along the root surfaces during the early phase of wound healing. The use of grafting material in combination with collagen membranes seems to improve clinical outcomes for furcation, but not intrabony, defects when compared to the use of membranes alone. Recently, collagen materials have also been applied in guided bone regeneration (GBR) and root coverage procedures with comparable success rates to non-absorbable expanded polytetrafluoroethylene (ePTFE) membranes and conventional subepithelial connective tissue grafts, respectively. Long-term clinical trials are still needed to further evaluate the benefits of collagen membranes in periodontal and peri-implant defects. This article will review the rationale for each indication and its related literature, both in vitro and in vivo studies. The properties that make collagen membranes attractive for use in regenerative therapy will be addressed. In addition, varieties of cross-linking techniques utilized to retard the degradation rate of collagen membranes will be discussed.

The angiogenic factor midkine is aberrantly expressed in NF1-deficient Schwann cells and is a mitogen for neurofibroma-derived cells

Loss of the tumor suppressor gene NF1 in neurofibromatosis type 1 (NF1) contributes to the development of a variety of tumors, including malignant peripheral nerve sheath tumors (MPNST) and benign neurofibromas. Of the different cell types found in neurofibromas, Schwann cells usually provide between 40 and 80%, and are thought to be critical for tumor growth. Here we describe the identification of growth factors that are upregulated in NF1-/- mouse Schwann cells and are potential regulators of angiogenesis and cell growth. Basic fibroblast growth factor (FGF-2), platelet-derived growth factor (PDGF) and midkine (MK) were found to be induced by loss of neurofibromin and MK was further characterized. MK was induced in human neurofibromas, schwannomas, and various nervous system tumors associated with NF1 or NF2; midkine showed an expression pattern overlapping but distinct from its homolog pleiotrophin (PTN). Immunohistochemistry revealed expression of MK in S-100 positive Schwann cells of dermal and plexiform neurofibromas, and in endothelial cells of tumor blood vessels, but not in normal blood vessels. Furthermore, MK demonstrated potent mitogenic activity for human systemic and brain endothelial cells in vitro and stimulated proliferation and soft agar colony formation of human MPNST derived S100 positive cells and fibroblastoid cells derived from an NF1 neurofibroma. The data support a possible central role for MK as a mediator of angiogenesis and neurofibroma growth in NF1. Oncogene (2001) 20, 97 - 105.

[The effect of temperature on the enantiomeric resolutions on albumin and beta-cyclodextrin chiral stationary phases]

The effect of column temperature on enantiomeric resolutions of tryptophan, warfarin and ketoprofen was investigated on bovine and human serum albumin (BSA and HSA) stationary phases, which were synthesized with s-triazine as the activator. It was observed that the entropy change made a great contribution to the separation of those enantiomers on albumin chiral stationary phases. The column temperature for the maximal resolution of tryptophan on the BSA stationary phase prepared by this method was about 35 degrees C, which was not 24 degrees C as reported for the BSA stationary phase synthesized with glutaric dialdehyde as the activator. This results may come from the different conformation of the immobilized BSA and HSA due to the different coupling methods used. On the other hand, it was indicated that the resolution of enantiomers on beta-CD chiral stationary phase was mainly contributed from the change of enthalpy, which means the resolution of chiral solutes on albumin and beta-CD stationary phases has different thermodynamic behaviors.

Relationship of sulcular sulfide level to severity of periodontal disease and BANA test

BACKGROUND

Volatile sulfur compounds (VSC), such as hydrogen sulfide and methyl mercaptan, are toxic metabolites produced by periodontal pathogens. Their relationship to periodontal disease severity is not yet fully understood. Hence, the aims of this study were to: 1) examine the relationship between sulcular sulfide (pS) levels and severity of periodontal disease and 2) examine the link between pS level and the BANA (benzoyl-DL-arginine-naphthylamide) test.

METHODS

Seventy systemically healthy subjects with a mean age of 53.0 +/- 13.8 years participated. Three sites were selected from each subject based upon radiographic bone loss (RBL): RBL < 2 mm, healthy; RBL > or = 2 to < 4, low to moderate; RBL > or = 4 mm, severe. Periodontal parameters, probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP), were recorded. The pS level was measured using a portable sulfide monitor in a digital score ranging from 0.0 (< 10(-7) M of S) to 5.0 (> or = 10(-2) M of S) in increments of 0.5. The presence of specific bacteria in subgingival plaque was detected using BANA test.

RESULTS

The mean pS level was 0.10 +/- 0.23, 0.36 +/- 0.48, and 1.10 +/- 0.87 for healthy, low to moderate, and severe disease sites, respectively, and was statistically different (P<0.001). The pS level was positively correlated with the BANA test, and was higher in untreated subjects than maintenance subjects (P<0.01).

CONCLUSIONS

The pS level may be a potential indicator for detecting severity of periodontal disease and identifying bacteria that are capable of hydrolyzing BANA.

[Immunologic properties of coli surface antigen 6(CS6) of enterotoxigenic Escherichia coli and cholera toxin subunit B expressed in Shigella flexneri 2a strain T32]

A host-plasmid balancing system composed with a delta asd mutant (FaD) of an avirulent strain (T32) of Shigella flexneri 2a and plasmid harboring asd gene was used to express enterotoxigenic E. coli surface antigen 6(CS6) and V. cholerae toxin subunit B (CTB). The results of Western blotting and ELISA showed that all of recombinant plasmids (pYX201, pYX202 and pYX203) could be maintained stably and expressed CS6 and CTB respectively in T32 without any antibiotic selection. All the recombinant bacterial strains could elicit the corresponding antibodies in rabbits. The antibodies against CTB elicited by both FaD/pYX201 and FaD/pYX203 showed to be high level, and had long prolongation time, in otherwise, the antibodies against CS6 showed to be low level, indicating that higher expression level of foreign antigen may be benefit for construction of genetic multivalent vaccine.

Relationship between sulcular sulfide level and oral malodor in subjects with periodontal disease

BACKGROUND

The relationship between oral malodor and sulfide levels in periodontal pockets (pS) has not yet been determined. The aims of this study were: 1) to identify the correlation among oral malodor, pS levels, and the BANA (benzoyl-DL-arginine-naphthylamide) test and 2) to recognize the interaction between oral malodor, demographic factors, tongue coating, and periodontal condition.

METHODS

Eighty-one periodontal patients participated in this study. A portable sulfide monitor and organoleptic method were used to evaluate oral malodor. Demographic data included age, gender, race, and smoking habits. The volume of tongue coating and periodontal condition for all teeth were assessed. The pS levels of 3 different radiographic bone loss (RBL) sites: RBL < 2 mm, healthy; RBL > or = 2 to < 4 mm; low to moderate; RBL > or = 4 mm, severe, were measured using an industrial sulcular sulfide-monitoring device. Subgingival plaque samples from the above 3 sites and tongue scraping were examined by the BANA test.

RESULTS

The volume of tongue coating (P<0.001), extent of periodontal disease (P<0.05), pS levels of the sites with low to moderate bone loss (P<0.05), and BANA score of tongue scrapings (P<0.05) were significantly associated with oral malodor. Stepwise multiple regression analysis examined the degree of association between oral malodor and potential explanatory variables. The volume of tongue coating and percent of sites BOP (bleeding on probing) were significantly associated with oral malodor. Females and smoking habit were negatively correlated with organoleptic measurements.

CONCLUSIONS

The pS level of the representative sites with low to moderate bone loss demonstrated a modest association with oral malodor. Oral malodor in periodontal patients was primarily associated with tongue coating and gingival inflammation.

Osmotic stress-induced changes of sucrose metabolism in cultured sweet potato cells

The intra- and extracellular sugar contents, the activities of sucrose-metabolizing enzymes, and the metabolism of [U-(14)C] glucose in a pulse-chase experiment were compared between the normal and osmotically stressed (by 0.6 M sorbitol) sweet potato (Ipomoea batatas) suspension cells. The stress enhanced the levels of sucrose and sucrose phosphate synthase (SPS) activity. Northern blot analysis also showed that prolonged osmotic stress enhanced the SPS gene expression at the transcriptional level. Stressed cells also had higher activities of sucrose cleaving enzymes, such as alkaline invertase and sucrose synthase. The (14)C-sucrose isolated from normal and stressed cells had (14)C-fructose and (14)C-glucose ratios of 0.68 and 1, respectively. These data suggest the continual cycling of degradation and synthesis of sucrose in both types of cells. Among the enzymes used in constructing such futile cycling, besides invertase and SPS, sucrose synthase (SS) should be involved in normal cells, but not in stressed ones. It is apparent that the osmotic stress caused a significant change in the pattern of sucrose metabolism.

[Effects of noise and music on EEG power spectrum]

Objective. To observe the effect of noise and music on EEG power spectrum. Method. 12 healthy male pilots aged 30 +/- 0.58 years served as the subjects. Dynamic EEG from 16 regions was recorded during quiet, under noise or when listening to music using Oxford MR95 Holter recorder. Changes of EEG power spectrum of delta, theta, alpha1, alpha2, beta1 and beta2, frequency components in 16 regions were analyzed. Result. The total alpha1 power was significantly decreased, while the total theta power was significantly increased when listening to music; It implies that the interhemispheric transmission of information in the frontotemporal areas might be involved. Conclusion. The changes of the EEG power spectrum were closely related to man's emotions; relaxation was associated with music; Individual difference exists in the influence of sound on EEG.

Supplemental systemic oxygen support using an intestinal intraluminal membrane oxygenator

An intraluminal membrane oxygenator (IMO) prototype was surgically inserted in the ileum and evaluated as a method of supporting systemic oxygenation in an acutely hypoxemic porcine model. Animals were assigned randomly to the test (n = 12) or the control (n = 8) groups, which underwent identical protocols with the exception of the O2 flow in the IMO device, which was shut off in the control group. In each case, hypoxia was induced by a reduction in the inspired oxygen fraction (FiO2) to 0.14. A highly significant improvement (p < 0.005) in arterial and venous O2 content and lower arteriovenous O2 difference (p < 0.05), cardiac output, and hemoglobin (p < 0.005) were found in the test group during hypoxia. The results show that it is possible to meet a physiologically significant portion of the body's O2 demands via the intestine during respiratory hypoxia and suggests that similar devices may be of significant potential value as a supplemental oxygenation device in cases of respiratory distress.

Fundamental gating mechanism of nicotinic receptor channel revealed by mutation causing a congenital myasthenic syndrome

We describe the genetic and kinetic defects in a congenital myasthenic syndrome due to the mutation epsilonA411P in the amphipathic helix of the acetylcholine receptor (AChR) epsilon subunit. Myasthenic patients from three unrelated families are either homozygous for epsilonA411P or are heterozygous and harbor a null mutation in the second epsilon allele, indicating that epsilonA411P is recessive. We expressed human AChRs containing wild-type or A411P epsilon subunits in 293HEK cells, recorded single channel currents at high bandwidth, and determined microscopic rate constants for individual channels using hidden Markov modeling. For individual wild-type and mutant channels, each rate constant distributes as a Gaussian function, but the spread in the distributions for channel opening and closing rate constants is greatly expanded by epsilonA411P. Prolines engineered into positions flanking residue 411 of the epsilon subunit greatly increase the range of activation kinetics similar to epsilonA411P, whereas prolines engineered into positions equivalent to epsilonA411 in beta and delta subunits are without effect. Thus, the amphipathic helix of the epsilon subunit stabilizes the channel, minimizing the number and range of kinetic modes accessible to individual AChRs. The findings suggest that analogous stabilizing structures are present in other ion channels, and possibly allosteric proteins in general, and that they evolved to maintain uniformity of activation episodes. The findings further suggest that the fundamental gating mechanism of the AChR channel can be explained by a corrugated energy landscape superimposed on a steeply sloped energy well.

Effects of tetrandrine on growth factor-induced DNA synthesis and proliferative response of rat pulmonary artery smooth muscle cells

The objective of the present study was to investigate the effect of tetrandrine (a plant alkaloid isolated from Stephenia tetrandra) on growth factor-induced DNA synthesis and proliferative responses of rat pulmonary artery smooth muscle cells. Male rat and bovine pulmonary artery smooth muscle cells (PASMC) were cultured in Medium 199 containing FBS (10%). DNA synthesis was monitored from [(3)H]-thymidine uptake and cell proliferation by direct cell counting. In the present study FBS (1% v/v) caused a small increase in DNA synthesis above basal levels in rat and bovine PASMC (6% and 11% respectively). Platelet-derived growth factor (PDGF, 50 ng/ml), fibroblast growth factor (FGF, 50 ng/ml) or interleukin-1alpha (IL-1alpha, 100 pg/ml) alone increased rat PASMC proliferation (69-85%) and DNA synthesis above basal levels (76-92%). The addition of these growth factors in combination with FBS (1%) resulted in higher increases in DNA synthesis above basal levels (rat PASMC:PDGF, 465%; FGF, 421%; IL-1alpha, 406%; bovine PASMC:PDGF, 279%). Tetrandrine (10(-5) M) inhibited FBS (10%)-induced rat PASMC proliferation (90.5%) and DNA synthesis (89.0%). Tetrandrine significantly inhibited cell proliferation (86.5-98.5%) and DNA synthesis (79.9-89.0%) induced by FBS (1%) in combination with one of the following mitogens; PDGF (50 ng/ml), FGF (50 ng/ml), IL-1alpha (100 pg/ml). The inhibitory effects of tetrandrine were observed between 10(-6) and 10(-5)M and PASMC viability was not affected by tetrandrine below 3x10(-5) m. In summary, these results suggest that tetrandrine can exert anti-proliferative effects against a range of mitogenic stimuli for vascular smooth muscle cells in vitro. Such effects may contribute to the inhibitory effect of tetrandrine on pulmonary vascular remodelling associated with pulmonary hypertension.

Point mutation associated with X-linked dominant Charcot-Marie-Tooth disease impairs the P2 promoter activity of human connexin-32 gene

Many lines of evidence suggest that connexin-32 gap junction is involved in the exchange of information and metabolites in the peripheral nervous system. It has been shown that connexin-32 protein and mRNA are expressed in Schwann cells that function as myelinating cells of the peripheral nervous system. The physiological importance of connexin-32 gap junctions in regulating the normal function of myelinating Schwann cell is indicated by recent findings that X-linked dominant Charcot-Marie-Tooth disease, a hereditary peripheral neuropathy, is associated with the mutations of connexin-32 gene. Recently, we encountered a Taiwanese family affected with X-linked dominant Charcot-Marie-Tooth neuropathy. Therefore, we investigated the possible mutation in the coding and noncoding regions of the connexin-32 gene of affected members of this family. Our results suggest that a G-to-A transition at the position -215 (in relation to the transcription initiation site) of the nerve-specific P2 promoter region is associated with the pathogenesis of X-linked dominant Charcot-Marie-Tooth disease. Further experiments using the promoter assay indicate that G-to-A mutation at the position -215 greatly impairs the transcriptional activity of connexin-32 P2 promoter. These findings propose that a reduced expression of connexin-32 mRNA and protein in the myelin sheath could be responsible for the development of X-linked dominant Charcot-Marie-Tooth neuropathy.

Breast cancer growth inhibition by delivery of the MDGI-derived peptide P108

Mammary derived growth inhibitor (MDGI) is a member of the family of cytoplasmic fatty acid binding proteins (FABPs), which bind hydrophobic ligands such as fatty acids, retinoids, eicosanoids and prostaglandines. MDGI and an 11 amino acid MDGI-derived conserved C-terminal peptide (P108) inhibits growth of normal mammary epithelial cells in tissue and organ culture, but fails to inhibit proliferation of many breast cancer cell lines in vitro. Here, the effects of peptide P108 on tumor growth of MCF-7, MDA-MB468 and MDA-MB231 human breast cancer cell lines in nude mice were tested. To deliver P108 into tumors, a novel peptide production system was applied for expression and secretion of small bioactive peptides in mammalian cells. Functional differentiation was observed in MCF-7 and MDA-MB468 cells upon P108 expression. In addition, EGF-dependent colony formation in soft agar by MDA-MB468 cells was inhibited by secreted P108. Tumor growth in athymic nude mice was suppressed in all three cell lines tested. Furthermore, P108 expressed by MCF-7/P108 cells caused paracrine tumor growth inhibition of MDA-MB231 cells. These results indicate that breast cancer inhibition by P108 is independent of binding to hydrophobic ligands and is perhaps mediated by interference with EGF-dependent signaling pathways.

Using absorbable collagen membranes for guided tissue regeneration, guided bone regeneration, and to treat gingival recession

This article reviews the role of barrier membranes in guided tissue regeneration (GTR) and guided bone regeneration (GBR), including the advantages of using absorbable barrier membranes in GTR and GBR and the unique properties of collagen membranes. The indications and contraindications for using collagen membranes for these procedures are examined, and successful cases are presented. Finally, the role of collagen membranes in the future of regenerative therapy is considered.

Hepatitis C virus core protein-induced loss of LZIP function correlates with cellular transformation

Hepatitis C virus (HCV) is the major etiological agent of blood-borne non-A non-B hepatitis and a leading cause of liver cirrhosis and hepatocellular carcinoma worldwide. HCV core protein is a multifunctional protein with regulatory functions in cellular transcription and virus-induced transformation and pathogenesis. Here we report on the identification of a bZIP nuclear transcription protein as an HCV core cofactor for transformation. This bZIP factor, designated LZIP, activates CRE-dependent transcription and regulates cell proliferation. Loss of LZIP function in NIH 3T3 cells triggers morphological transformation and anchorage-independent growth. We show that HCV core protein aberrantly sequesters LZIP in the cytoplasm, inactivates LZIP function and potentiates cellular transformation. Our findings suggest that LZIP might serve a novel cellular tumor suppressor function that is targeted by the HCV core.

A cluster of Ser/Thr residues at the C-terminus of mu-opioid receptor is required for G protein-coupled receptor kinase 2-mediated desensitization

To investigate the functional role of G protein-coupled receptor kinases (GRK) in homologous desensitization of the mu-opioid receptor, human embryonic kidney (HEK) 293 cells, which express a significant level of GRK2, were stably transfected with the cDNA encoding the rat mu-opioid receptor. Wild-type mu-opioid receptors developed homologous desensitization after 30 min pretreatment with DAMGO ([D-Ala2,N-methyl-Phe4,Gly-ol5]enkephalin), a specific mu-opioid receptor agonist. The ability of mu-opioid receptors to develop homologous desensitization was greatly impaired following the transfection of a cDNA fragment encoding the GRK2(495-689) polypeptide, which is believed to block Gbetagamma-mediated transduction events including the membrane translocation and activation of GRK2. The mu(Cdelta45) receptor, a deletion mutant that lacks 45 C-terminal amino acids, failed to exhibit homologous desensitization after 30 min pretreatment of DAMGO. The mu(Cdelta41) receptor, which differs from the mu(Cdelta45) receptor by having four more Ser/Thr residues (Thr354Ser355Ser356Thr357), developed GRK2-mediated desensitization. These results suggest that homologous desensitization of rat mu-opioid receptors results from the activation of GRK2 and that a cluster of Ser/Thr residues (Thr354Ser355Ser356Thr357) at the intracellular carboxyl tail plays an important role in GRK2-mediated mu-opioid receptor desensitization.

Corticotropin-releasing factor produces a protein synthesis--dependent long-lasting potentiation in dentate gyrus neurons

Corticotropin-releasing factor (CRF) was shown to produce a long-lasting potentiation of synaptic efficacy in dentate gyrus neurons of the rat hippocampus in vivo. This potentiation was shown to share some similarities with tetanization-induced long-term potentiation (LTP). In the present study, we further examined the mechanism underlying CRF-induced long-lasting potentiation in rat hippocampus in vivo. Results indicated that the RNA synthesis inhibitor actinomycin-D, at a concentration that did not change basal synaptic transmission alone (5 microgram), significantly decreased CRF-induced potentiation. Similarly, the protein synthesis inhibitor emetine, at a concentration that did not affect hippocampal synaptic transmission alone (5 microgram), also markedly inhibited CRF-induced potentiation. These results suggest that like the late phase of LTP, CRF-induced long-lasting potentiation also critically depend on protein synthesis. Further, prior maximum excitation of dentate gyrus neurons with tetanization occluded further potentiation of these neurons produced by CRF and vise versa. Moreover, quantitative reverse transcription-polymerase chain reaction analysis revealed that CRF mRNA level in the dentate gyrus was significantly increased 1 h after LTP recording. Together with our previous findings that CRF antagonist dose-dependently diminishes tetanization-induced LTP, these results suggest that both CRF-induced long-lasting potentiation and tetanization-induced LTP require protein synthesis and that CRF neurons are possibly involved in the neural circuits underlying LTP.