Taxane diterpenoids from the stem bark of Taxus mairei

Three new 11(15-->1)-abeo-taxanes, taxumairols U-W (1-3), have been isolated from extracts of the stem bark of Formosan Taxus mairei. The structures of 1-3 were identified as 5alpha,7beta,9alpha,13alpha,20-pentaacetoxy-2alpha,10beta,15-trihydroxy-11(15-->1)-abeo-taxene, 5alpha,7beta,9alpha,20-tetraacetoxy-2alpha,10beta,13alpha,15-tetrahydroxy-11(15-->1)-abeo-taxene, and 2alpha,4alpha,7beta,10beta-tetraacetoxy-5beta,20-epoxy-9alpha,13alpha,15-trihydroxy-11(15-->1)-abeo-taxene, respectively, on the basis of 2D NMR techniques including COSY, HSQC, HMBC, and NOESY experiments as well as chemical reactions of compounds 1-3 to give 4 (5alpha,7beta,9alpha,10beta,13alpha,20-hexaacetoxy-2alpha,15-dihydroxy-11(15-->1)-abeo-taxene) and 5 (4alpha,7beta,10beta-triacetoxy-9alpha,13alpha-dibenzoxy-5beta,20-epoxy-2alpha,15-dihydroxy-11(15-->1)-abeo-taxene), which are also novel taxane derivatives. Taxumairols U (1) and V (2) exhibited significant cytotoxicities against human hepatoma tumor cells, while taxumairol W (3) was inactive.

TNF-α increases sensitivity to LPS in chronically catheterized rats

Patients with severe trauma injury are transiently exposed to increased serum concentrations of tumor necrosis factor-α (TNF-α). These patients are susceptible to the development of multisystem organ failure (MSOF) triggered by subsequent exposure to bacterial toxins either via infection or increased intestinal permeability. We simulated the cytokine response of trauma by infusing 0.8 or 8.0 μg/kg of TNF-α (priming dose) into chronically catheterized rats. After 48 h, rats were challenged with endotoxin [lipopolysaccharide (LPS); 10 or 1,000 μg/kg]. Animals primed with either dose of TNF-α and then challenged with 1,000 μg/kg of LPS demonstrated significantly increased mortality, mean peak serum concentrations of interferon-γ (IFN-γ), and blood lactate concentrations ( P < 0.05) compared with nonprimed animals. Mean peak serum concentrations of IFN-γ and blood lactate concentrations were increased after challenge with 10 μg/kg of LPS only in animals primed with 8.0 μg/kg of TNF-α. Priming with TNF-α did not increase mortality after challenge with 10 μg/kg of LPS. These data suggest that both TNF-α release and the subsequent exposure to bacterial toxins mediate the pathophysiological progression from trauma to subsequent MSOF.

Five-color-based high-information-content fingerprinting of bacterial artificial chromosome clones using type IIS restriction endonucleases

We have developed a high-information-content fingerprinting (HICF) system for bacterial artificial chromosome (BAC) clones using a Type IIS restriction endonuclease, HgaI, paired with a Type II restriction endonuclease, RsaI. In the method described, unknown five-base overhangs generated with HgaI are partially or fully sequenced by modified fluorescent dideoxy terminators. Using an in-lane size standard labeled with a fifth dye, fragments are characterized by both the size and the sequence of its terminal one to five bases. The enhanced information content associated with this approach significantly increases the accuracy and efficiency of detecting shared fragments among BAC clones. We have compared data obtained from this method to predicted HICF patterns of 10 fully sequenced BACs. We have further applied HICF to 555 BAC clones to assemble contigs spanning 16p11.2 to 16p13.1 of human chromosome 16.

[Extraction and analysis of profenofos residue in tomato and cabbage by gas chromatography-flame photometric detector]

A quick and effective extraction and clean-up method of profenofos residue in tomato and cabbage is presented. Tomato and cabbage samples were homogenized with a mixture of acetone-hexane (1:1, V/V) using a mechanical homogenizer. The resultant homogenate was cleaned-up by adding active carbon and then filtered under reduced pressure. The filter cake was extracted twice with the same solvent mixture. The filtrates were combined and transferred into a separatory funnel. The organic layer was separated and evaporated to dryness using a rotary evaporator. The residue was dissolved in 2 mL of acetone and transferred into a small glass vial and then determined by GC on a 5% OV-101 Chromosorb W-HP column with flame photometric detector. The results showed that this analytical method can be used for an accurate determination of profenofos residues in tomato and cabbage. The minimum detectable concentration of profenofos in samples was 0.06 mg/kg. The recoveries of profenofos in tomato and cabbage were in the range of 96.2%-105.9% and 94.7%-102.3%, respectively. The relative standard deviations were in the range of 3.7%-4.9% and 3.7%-5.0%, respectively. The tomato and cabbage samples were collected 3 weeks after applying profenofos in the field, and the contents of profenofos were determined. The average contents of profenofos in tomato and cabbage were (13.8 +/- 0.8) mg/kg and (14.4 +/- 0.7) mg/kg, respectively.

Cloning, Mapping, and Characterization of the Human Sorbin and SH3 Domain Containing 1 (SORBS1) Gene: A Protein Associated with c-Abl during Insulin Signaling in the Hepatoma Cell Line Hep3B

SH3P12/CAP/ponsin, a gene product with a sorbin homology domain and three consecutive SH3 domains in the carboxy-terminus, has been isolated from murine adipocytes and identified as an important adaptor during insulin signaling. Here we describe the cloning, mapping, and expression of the human homologue, termed SORBS1 (sorbin and SH3 domain containing 1). Multiple transcripts of this gene with different mRNA isoforms were observed among different tissues. Here we report 13 alternatively spliced exons, which were ascertained from the full-length cDNA cloned in adipose, liver, and skeletal muscle tissues. Among the major isoforms, the shortest, 2223-bp, open reading frame (ORF) encodes a protein with a predicted molecular weight of 81.5 kDa, while the longest, 3879-bp, ORF encodes a protein of about 142.2 kDa. This gene was mapped to human chromosome 10q23.3-q24.1, which is a candidate region for insulin resistance found in Pima Indians. In human hepatoma Hep3B cells, SORBS1 was partly dissociated from the insulin receptor complex and bound to c-Abl protein upon insulin stimulation. This interaction with c-Abl was through the third SH3 domain and a possible conformational change of SORBS1 induced by insulin. Our data suggest that c-Abl oncoprotein via SORBS1 might play a role in the insulin signaling pathway.

Dynamic magnetic resonance imaging technique for the study of the temporomandibular joint

AIMS

Echo planar imaging (EPI) is an ultrafast magnetic resonance imaging (MRI) technique that can scan a single frame in less than a second. The aim of this study was to use the EPI technique to develop a new dynamic MRI protocol for the temporomandibular joint (TMJ).

METHODS

Basic fast-field echo and EPI pulse sequences were used for dynamic studies of the TMJ. The subjects were instructed to perform spontaneous, continuous, slow opening/closing movements without visual or audio feedback. Different scanning parameter settings were explored to optimize the results.

RESULTS

With an opening/closing movement of approximately 6 to 7 seconds per cycle, the proposed protocol yielded a good insight into the relative motion between condyle and disc. It was also possible to see the deformation of the disc during movement.

CONCLUSION

The EPI technique is a non-invasive technique that can be used for dynamic imaging study of a slow but continuous, uninterrupted jaw movement.

Individualized oblique-axial magnetic resonance imaging for improved visualization of mediolateral TMJ disc displacement

AIMS

A new individualized oblique-axial orientation of magnetic resonance imaging scans of the temporomandibular joint (TMJ), corrected to be perpendicular to the tangent of the posterior slope of the articular eminence, has been proposed to improve the representation of the disc. The aim of this study was to evaluate the quality of the images obtained with this new type of scanning plane and to assess the factors that can affect the scans.

METHODS

Twenty-nine TMJs were scanned by the use of sagittal, conventional coronal, and individualized oblique-axial scanning planes. On the sagittal images, the angle alpha between the tangent of the posterior slope of the articular eminence and the vertical was measured, and the disc position was evaluated. For both imaging planes, 2 examiners, blind to the scanning techniques, counted the number of conventional coronal and oblique-axial scans in which the disc was visible and in which the medial and lateral disc borders were well demarcated and evaluated the mediolateral disc position.

RESULTS

The individualized oblique-axial technique was superior to the conventional coronal technique in depicting the disc and its medial and lateral demarcations (paired t test, P < 0.05). The possibility of correct diagnosis of the mediolateral disc position and the agreement between the observers in this evaluation were better with the oblique-axial technique than with the conventional technique (P < 0.05). This was particularly evident when the disc was anteriorly displaced.

CONCLUSION

The individualized oblique-axial scanning planes should be used for a better representation of the disc/condyle complex mediolaterally if the disc is anteriorly displaced.

Predicting factors of malignancy in dermatomyositis and polymyositis: a case-control study

BACKGROUND

An association between dermatomyositis (DM)/polymyositis (PM) and malignancies has been widely reported in the literature. The validity of extensive evaluation for malignancies in those patients has also been questioned for decades. Only limited papers regarding the signs of malignancy and the prognostic factors in DM/PM have been reported.

OBJECTIVES

To define the potential risk factors of concomitant neoplastic diseases in patients diagnosed as having DM/PM.

METHODS

From 1 April 1983 to 30 June 1999, 147 patients were diagnosed as having probable or definite DM/PM at the Veterans General Hospital, Taichung, Taiwan. We excluded four patients who had preceding neoplastic diseases diagnosed before DM/PM, then retrospectively reviewed the data of the remaining 143 patients and subgrouped the cases as four main types: primary idiopathic DM, primary idiopathic PM, juvenile DM/PM and amyopathic DM (ADM). We next performed univariate analysis using logistic regression to evaluate the possible predictive factors for malignancies, such as mean age at onset, gender, manifestations at onset, association with other connective tissue diseases, initial skin presentations, complications and laboratory data. Then we chose the significant factors for multivariate analysis by logistic regression, to determine the independent risk factors of malignancies in DM/PM patients.

RESULTS

Among the 143 patients, DM was the most common type (64%), followed by ADM (14%), juvenile DM/PM (13%) and PM (10%). The mean age at onset overall was 42.4 years. Other connective tissue diseases were present in 22% of all patients, especially PM (50%) and juvenile DM/PM patients (28%). Internal malignancies were present in 13% of patients, and most were associated with DM. Nasopharyngeal carcinomas (NPCs) were the most common tumours. Patients with primary idiopathic DM, with an older age at onset, higher serum creatine phosphokinase levels and male gender, had more chance of developing concomitant malignancies. Those associated with complications, especially interstitial lung diseases, had a lower risk of associated neoplasia. In multivariate analysis, an older age at onset (odds ratio 9.10) and male gender (odds ratio 4.06) were associated with greater risk of developing malignancies.

CONCLUSIONS

The two independent predictive factors for malignancy (P < 0.05) in patients with DM/PM were an older age at onset (> 45 years) and male gender. The primary idiopathic DM group was shown to have higher risk of developing internal malignancies, especially NPC. However, this was not identified as an independent predictive factor for concomitant neoplastic diseases in multivariate analysis. In addition, patients who had the complication of interstitial lung disease had a significantly lower frequency of malignancies (P < 0.001).

Six new dammarane-type triterpene saponins from the leaves of Panax ginseng

Six new minor saponins, together with known ginsenosides, were isolated from the leaves of Panax ginseng. The new saponins were named as ginsenoside-Rh5, -Rh6, -Rh7 -Rh8, -Rh9 and -Rg7, and their structures were elucidated on the basis of chemical and physicochemical evidence to be as follows: ginsenoside-Rh5: 3beta,6alpha,12beta,24zeta-tetrahydroxy-dammar-20(22),25-diene 6-O-beta-D-glucopyranoside (1), -Rh6: 3beta,6alpha12beta,20(S)-tetrahydroxy-25-hydroperoxy-dammar-23-ene 20-O-beta-D-glucopyranoside (2), -Rh7: 3beta,7beta,12beta,20(S)-tetrahydroxy-dammar-5,24-diene 20-O-beta-D-glucopyranoside (3), -Rh8: 3beta,6alpha,20(S)-trihydroxy-dammar-24-ene-12-one 20-O-beta-D-glucopyranoside (4), -Rh9: 3beta,6alpha,20(S)-trihydroxy-12beta,23-epoxy-dammar-24-ene 20-O-beta-D-glucopyranoside (5) and -Rg7: 3-O-beta-D-glucopyranosyl 3beta,12beta,20(S),24(R)-tetrahydroxy-dammar-25-ene 20-O-beta-D-glucopyranoside (6).

An effective strategy of using molecular testing to screen mentally retarded individuals for fragile X syndrome

Fragile X syndrome (FXS) is the most common form of familial mental retardation (MR). It is caused by the expansion of the CGG repeat in the FMR1 gene on the X chromosome. To date, FXS is not treatable, but can be prevented by prenatal genetic examination. Identifying women who carry a full mutation or premutation FMR1 gene is thus very important, and can be done by tracing family members of FXS subjects. However, most of the FXS subjects in Taiwan as well as those in many other countries have not been identified. In this study the authors attempt to develop reliable and inexpensive tests suitable for a large-scale screen of subjects with MR for FXS. Together with their previous study, a total of 311 male and 160 female subjects with MR were screened with nonradioactive Southern blot assay using mixed deoxyribonucleic acid from three subjects of the same sex. From these subjects, nine male subjects and one female FXS subject were diagnosed. All male subjects were also screened with nonradioactive polymerase chain reaction (PCR). These nine male FXS subjects were also detected on the basis of PCR amplification failure. No false-negative results were discerned. The PCR procedure was simplified further by combining it with an analysis of a blood spot on filter paper, which is a much simpler and cheaper method for sample collection and DNA preparation. This method was then used to screen 104 boys with MR. Two of them were suspected, and later confirmed with Southern blot assay, as subjects with FXS. This study suggests that simple PCR combined with blood spot analysis could be a reliable, inexpensive test that is feasible for a large-scale screening of male subjects with MR for FXS. However, Southern blot assay with mixed deoxyribonucleic acid is appropriate for screening female subjects. Based on this strategy, most FXS subjects could be identified easily for further management.

Thrombin-stimulated growth, clustering, and collagen lattice contraction of human gingival fibroblasts is associated with its protease activity

BACKGROUND

Thrombin is a serine protease produced following gingival tissue injury or inflammation. It regulates the functional behavior of injury-neighboring cells via the activation of specific protease-activated receptors (PAR). Thrombin's role in gingival tissue healing and inflammatory response processes is not yet well understood.

METHODS

We investigated the effects of thrombin on gingival fibroblast (GF) growth [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay], collagen lattice contraction, and associated morphological changes.

RESULTS

Thrombin (>1 U/ml), but not thrombin receptor (PAR-1) agonist peptide (SFLLRN, single letter amino acid code, abbreviated as TRAP, 1 to 50 microg/ml), stimulated the growth and clustering of cultured human GF in vitro. Growth-stimulatory effects of thrombin were inhibited by D-Phe-Pro-ArgCH2Cl (PPACK), a serine protease inhibitor. By contrast, trypsin (>10 microg/ml), a PAR-2 activator, suppressed the growth of GF. Thrombin (>0.2 U/ml) and TRAP (10 to 25 microg/ml), but not trypsin, prostaglandin E2 (0.01 to 0.5 microg/ml), or bovine serum albumin (BSA) (1 to 80 microg/ml), induced the GF-populated collagen lattice contraction within 30 to 60 minutes of exposure. The thrombin-induced collagen lattice contraction was inhibited by PPACK (20 microg/ml) and an actin filament polymerization inhibitor, cytochalasin B (1 microg/ml). The collagen lattice contraction induced by TRAP was also inhibited by cytochalasin B, but not by PPACK. Using a reverse-transcriptase polymerase chain reaction (RT-PCR), the expression of PAR-1, and to a lesser extent PAR-3, was observed for human GF, although little PAR-2 and PAR-4 expression was noted.

CONCLUSIONS

These results indicate that thrombin is important in periodontal wound healing and inflammatory processes by promoting the growth and contraction of GF. The stimulatory effects of thrombin are associated with its protease activation of thrombin receptors.

[A study on the relationship between the changes of salivary EGF and oromaxillofacial tumors]

OBJECTIVE

To investigate the relationship between the changes of salivary epidermal growth factor (sEGF) concentration and oromaxillofacial tumors so as to find out its potential clinical value.

METHODS

The saliva of 123 patients with oromaxillofacial tumors,inflammations and precancerous lesions were measured for EGF concentration by radioimmunoassay (RIA) with the ligand(125)I-EGF and the saliva of 40 normal adults as the control.

RESULTS

Compared with the control, sEGF level of malignant,benign salivary gland tumors increased obviously;the former is higher than the latter significantly. The sEGF levels of patients with squamous cell carcinoma (SCC) of mucosa,recurrence and precancerous lesion were significantly higher than that of the control. There was no significant difference among the groups,but there was a tendency to increase by degrees. Compared with the control,the increase of the sEGF level of SCC patients with lymph node metastasis was of no significance. The sEGF level of oromaxillofacial inflammation was significantly higher than that of control.

CONCLUSION

The sEGF levels in patients with salivary gland tumor,SCC,inflammation increased in different degrees.

Effects of Nd:YAG laser irradiation on cultured human gingival fibroblasts

BACKGROUND AND OBJECTIVE

The Nd:YAG laser has been proposed to apply in minor soft tissue surgery, including various periodontal procedures. However, little information is available regarding the direct effect of Nd:YAG laser on gingival fibroblasts, which play an important role in the early healing processes of periodontal repair.

STUDY DESIGN/MATERIALS AND METHODS

Nd:YAG laser irradiation was performed in pulsed mode on human gingival fibroblasts, which was derived from healthy human gingiva by an explant method. The size of laser diode was 400 microm in diameter. The parameters in laser delivery were pulse energy (50-150 mJ), power output (1.0-3.0 W), pulse rate (10-30 pps), and fixed duration of irradiation (10 seconds). The cell cultures were analysed by cytomorphologic examination under phase-contrast and scanning electron microscope. The vitality was also examined with the help of MTT staining.

RESULTS

The area of laser damage on cell culture was circular in shape, with diameter beyond the size of laser diode. By scanning electron microscopy, we observed the cellular damage of cultured gingival fibroblasts induced by Nd:YAG laser irradiation, comparable with the progressive increased power settings. The cytomorphologic changes ranged from disappearance of cellular boundary, loss of identifiable cellular nucleus, and finally cell contraction and vacuolization. Significant decrease in cellular vitality (14% approximately 44%) after laser treatment with irradiation distance of nearly contact was noted. However, 2 mm defocusing irradiation with the same power settings did not significantly decrease cellular vitality.

CONCLUSION

Our study demonstrated the cell damaging effects of Nd:YAG laser, ranging from degeneratively cytomorphologic change to cell death, on the cultured human gingival fibroblasts. It provided the dentist a chance to understand the potential hazard of laser application in periodontal treatment. If the energy output is enough for the clinical purposes, Nd:YAG laser with lower pulse energy and corresponding pulse rate should be selected to minimize the damage on adjacent soft tissue.

Initial sequencing and analysis of the human genome

The human genome holds an extraordinary trove of information about human development, physiology, medicine and evolution. Here we report the results of an international collaboration to produce and make freely available a draft sequence of the human genome. We also present an initial analysis of the data, describing some of the insights that can be gleaned from the sequence.

The inhibitory effects of ginsenosides on protein tyrosine kinase activated by hypoxia/reoxygenation in cultured human umbilical vein endothelial cells

27 individual ginsenosides and aglycones, together with five extracts from ginseng roots, ginseng leaves, American ginseng roots, American ginseng leaves and non-saponin fraction from roots of Panax ginseng, were tested for their effects on protein tyrosine kinase (PTK) activation induced by an in vitro hypoxia/reoxygenation (H/R) model in cultured human umbilical vein endothelial cells (HUVEC). The results indicated that ginsenoside-Rb1 (3), -Rd (7), -Ra1 (1) and -Ro (27) showed significant inhibitory effects on PTK activation induced by H/R. Dose-response experiments revealed that ginsenoside-Rb1 was the most active compound and it completely blocked PTK activation at a wide range of concentrations. Most protopanaxadiol-type ginsenosides and some protopanaxatriol-type saponins also showed significant effects on PTK activation. However, the crude extracts did not protect against H/R-induced PTK activation.

The antioxidant caffeic acid phenethyl ester induces apoptosis associated with selective scavenging of hydrogen peroxide in human leukemic HL-60 cells

Caffeic acid phenethyl ester (CAPE), an active component of propolis, has many biological and pharmacological activities including antioxidation and tumor cell cytotoxicity. We examined the type of cell death in human leukemic HL-60 cells after CAPE treatment in order to elucidate the relationship between CAPE-induced alterations of the redox state and apoptosis. CAPE treatment (6 microg/ml) resulted in marked growth inhibition up to 70.3+/-4.0% at day 2. This inhibition was partially blocked by pretreatment with N-acetyl-L-cycteine (NAC). Agarose gel electrophoresis showed evident DNA fragmentation after CAPE treatment. CAPE induced a significant decrease in mitochondrial transmembrane potential to about half of the untreated level after 6 h and a rapid depletion of intracellular glutathione (GSH) down to 41.7+/-6.0% after 1 h. Pretreatment of HL-60 cells with NAC reversed the GSH depletion and partially rescued cells from CAPE-induced apoptosis. With regard to intracellular reactive oxygen species, CAPE caused a fast and profound scavenging of H202 (19% of untreated cells after a 2-h treatment) but not of superoxide anion. These results suggest that apoptosis induced by CAPE is associated with mitochondrial dysfunction, GSH depletion and selective scavenging of H2O2 in human leukemic HL-60 cells.

[Study on the expression of fibronectin after cerebral contusion in rats for timing of injuries]

An experimental model of reproducible focal cerebral contusions in rats was made by a free-drop impacting right hemisphere. The expression of fibronectin and its mRNA after cerebral contusion were detected respectively by immunohistochemical staining and in situ hybridization. Results indicated that the expression of fibronectin and its mRNA increased after injury, and there existed a relationship between increased fibronectin and its mRNA and different intervals after brain injury. It is inferred that the expression of fibronectin and its mRNA can be used for timing of brain injuries and distinguishing antemortem and postmortem brain contusions.

Characterization of the AdoMet-dependent guanylyltransferase activity that is associated with the N terminus of bamboo mosaic virus replicase

Bamboo mosaic virus (BaMV), a member of the potexvirus group, infects primarily members of the Bambusoideae. Open reading frame 1 (ORF1) of BaMV encodes a 155-kDa polypeptide that has long been postulated to be a replicase involved in the replication and formation of the cap structure at the 5' end of the viral genome. To identify and characterize the enzymatic activities associated with the N-terminal domain of the BaMV ORF1 protein, the intact replicase and two C-terminally truncated proteins were expressed in Saccharomyces cerevisiae. All three versions of BaMV ORF1 proteins could be radiolabeled by [alpha-(32)P]GTP, which is a characteristic of guanylyltransferase activity. The presence of S-adenosylmethionine (AdoMet) was essential for this enzymatic activity. Thin-layer chromatography analysis suggests that the radiolabeled moiety linked to the N-terminal domain of the BaMV ORF1 protein is m(7)GMP. The N-terminal domain also exhibited methyltransferase activity that catalyzes the transfer of the [(3)H]methyl group from AdoMet to GTP or guanylylimidodiphosphate. Therefore, during cap structure formation in BaMV, methylation of GTP may occur prior to transguanylation as for alphaviruses and brome mosaic virus. This study establishes the association of RNA capping activity with the N-terminal domain of the replicase of potexviruses and further supports the idea that the reaction sequence of RNA capping is conserved throughout the alphavirus-like superfamily of RNA viruses.

A pair of 24-hydroperoxyl epimeric dammarane saponins from flower-buds of Panax ginseng

Further investigation on the saponins of the flower-buds of Panax ginseng C. A. Meyer has resulted in the isolation and structural elucidation of a pair of new 24-epimers of dammarane type saponins named ginsenoside I and II. The structures of the epimers were characterized on the basis of chemical and spectral evidence as 3-O-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl]-20-S-O-beta-D-glucopyranosyl-3beta, 12beta,20(S)-trihydroxy-24xi-hydroperoxydammar-25-ene, except for their C-24 configurations. Ginsenoside I is a new triterpene glycoside, and ginsenoside II is a known compound first isolated from a natural plant.

Cyclic nucleotide phosphodiesterase type 5 activity limits blood flow to hypoperfused myocardium during exercise

BACKGROUND

Nitric oxide (NO) causes vasodilation by stimulation of guanylate cyclase in vascular smooth muscle to produce cGMP. The resultant vasodilator effect is regulated by a family of cGMP phosphodiesterases (PDEs). Sildenafil, a selective inhibitor of PDE5 used for treatment of erectile dysfunction, has been found to cause relaxation of isolated epicardial coronary artery segments. The present study examined the effects of sildenafil on coronary blood flow and hemodynamics during exercise in normal and ischemic heart.

METHODS AND RESULTS

In chronically instrumented normal dogs, sildenafil 2 mg/kg PO caused a slight but significant increase in left anterior descending (LAD) coronary blood flow during resting conditions, with a nonsignificant trend toward increased coronary flow during treadmill exercise. Exercise in the presence of LAD stenosis that decreased distal coronary pressure to 57+/-2 mm Hg reduced LAD flow during exercise from 69+/-8 to 41+/-7 mL/min (P:<0. 05), with hypoperfusion most severe in the subendocardium. At the same distal coronary pressure, sildenafil increased LAD flow in the ischemic region to 50+/-11 mL/min (P:<0.05). Increase in ischemic region blood flow produced by sildenafil was uniform across the LV wall, given that no change occurred in the transmural distribution of perfusion.

CONCLUSIONS

Inhibition of PDE5 with sildenafil caused vasodilation of coronary resistance vessels with an increase of blood flow into an ischemic myocardial region during exercise in the presence of coronary artery stenosis.

Loss of myocardial CK-MB into the circulation following 3.5 hours of swimming in a rat model

The purpose of this study was to document alterations of creatine kinase-B (CK-B) in the left and right ventricles of rats and CK-MB release into the circulation following a single bout of stressful prolonged intense exercise. Male Sprague-Dawley rats, with 8% bodyweight attached to each tail, were forced to swim 3.5 hours and were then sacrificed immediately (0 h PS), 3 hours (3 h PS), 24 hours (24 h PS), and 48 hours (48 h PS) post swimming, respectively. Sedentary (control) rats were sacrificed at rest. Serum CK-MB mass increased 2.1 times (8.9 microg/L; p < 0.01 vs. controls of 4.3 microg/L) and 1.4 times (6.0 microg/L; P < 0.01 vs. controls) at 0 h PS, and 3 h PS, respectively, and returned to baseline at 24 h PS. Western blot analysis indicated that CK-B of the right ventricle decreased 14% (p < 0.05), 20% (p < 0.01), and 12% (p < 0.05) at 3h PS, 24h PS and 48h PS, respectively. The CK-B of the left ventricles decreased 34% (p < 0.05) at 0 h PS, returned to baseline at 3 h PS, and was increased 39% (P < 0.01) at 48 h PS. Our findings demonstrate that a single bout of stressful, prolonged, intense exercise resulted in CK-B subunit loss from the myocardium, resulting in increased serum CK-MB concentrations, an indication of myocardial injury.

Comparison of anti-leukemic immunity against U937 cells in endurance athletes versus sedentary controls

To examine whether endurance athletes have higher anti-leukemic immunity than sedentary controls or not, we isolated peripheral blood mononuclear cells (MNC) from cyclists and sedentary controls to prepare conditioned media (CM) with various doses of phytohemagglutinin (PHA). The proliferation-inhibiting and differentiation-inducing activities of these PHA-MNC-CM on human leukemic U937 cells were investigated. Our results show that the growth inhibition activity of cyclists' PHA-MNC-CM were higher than that of controls. The dosage of PHA used to prepare MNC-CM to achieve about 90% growth inhibition was 5 microg/ml in the control group and was 2 microg/ml in the athletes group. The differentiation-inducing effects were evaluated by morphological scoring, superoxide production, and monocyte-associated antigen expression (CD14 and CD68). These three parameters all demonstrated the differentiation-inducing effect of MNC-CM increased with increasing dose of PHA. These effects were significantly greater in the athletic when compared to the sedentary control group at all doses of PHA. The levels of TNF-alpha and IFN-gamma PHA-MNC-CM increased in a PHA dose-dependent manner and were much higher in the athletic group when compared to the controls. We conclude that the capacity of endurance athletes to activate anti-leukemic immunity is significantly higher than that of sedentary controls.

Arrhythmogenic activity of cardiac muscle in pulmonary veins of the dog: implication for the genesis of atrial fibrillation

OBJECTIVE

Pulmonary veins are important foci of ectopic beats to initiate paroxysmal atrial fibrillation. The purpose of this study were to investigate the electrophysiological characteristics of excitable cells in canine pulmonary veins obtained from healthy and chronic rapid atrial pacing dogs and their responses to cardioactive agents.

METHODS

Transmembrane action potentials (APs) were recorded from multiple sites of pulmonary veins isolated from 17 healthy dogs and 14 dogs with chronic (6-8 weeks) rapid atrial pacing (780 bpm).

RESULTS

In normal superfusate, several types of electrical activities were identified, including silent electrical activity, fast response APs driven by electrical stimulation, and spontaneous fast or slow response APs (with or without early afterdepolarizations). The incidences of AP with an early afterdepolarization (93% versus 41%) was greater in chronic pacing dogs. The spontaneous activities were depressed by beta-adrenoceptor blocker, calcium channel blocker, adenosine and acetylcholine. High frequency (>8 Hz) irregular rhythms occurred spontaneously or were induced by cardioactive agents or electrical stimuli. The incidence of spontaneously occurring tachyarrhythmias was much higher in preparations from chronic pacing dogs (93%) than from control (12%). The tachyarrhythmias were suppressed by sodium channel blocker, potassium channel blocker or magnesium.

CONCLUSIONS

Pulmonary veins have arrhythmogenic ability through spontaneous activities or high-frequency irregular rhythms. The higher incidence of spontaneously occurring high-frequency irregular rhythms in chronic rapid atrial pacing dogs may account for the increased risk of atrial fibrillation in these dogs.

An analysis of meiotic pairing in trisomy 21 oocytes using fluorescent in situ hybridization

We report the use of chromosome 21-specific painting probes to analyze early stages of oogenesis in nine trisomy 21 fetuses. The proportion of cells in zygotene and pachytene in the trisomic ovaries ranged from 8 to 70% with a mean of 42% +/- 19 while the comparable values of euploid specimens ranged from 34 to 90% with a mean of 65% +/- 19. The low proportion of pairing cells may be the basis for the ovarian dysgenesis observed in some trisomy infants. Five percent of trisomic pachytene cells exhibited complete asynapsis which is an order of magnitude higher than that observed in euploid cells. A large fraction of the asynaptic cells were atretic which is consistent with the hypothesis of meiotic pairing as a signal for atresia. In addition, the asynaptic cells exhibited asynapsis of chromosomes other than 21, which we interpret as an interchromosomal effect of trisomy 21.