Enterococcus faecalis Extracellular Vesicles Promote Apical Periodontitis.

Enterococcus faecalis is an important contributor to the persistence of chronic apical periodontitis. However, the mechanism by which E. faecalis infection in the root canals and dentinal tubules affects periapical tissue remains unclear. Bacterial extracellular vesicles (EVs) act as natural carriers of microbe-associated molecular patterns (MAMPs) and have recently attracted considerable attention. In this study, we investigated the role of EVs derived from E. faecalis in the pathogenesis of apical periodontitis. We observed that E. faecalis EVs can induce inflammatory bone destruction in the periapical areas of mice. Double-labeling immunofluorescence indicated that M1 macrophage infiltration was increased by E. faecalis EVs in apical lesions. Moreover, in vitro experiments demonstrated the internalization of E. faecalis EVs into macrophages. Macrophages tended to polarize toward the M1 profile after treatment with E. faecalis EVs. Pattern recognition receptors (PRRs) can recognize MAMPs of bacterial EVs and, in turn, trigger inflammatory responses. Thus, we performed further mechanistic exploration, which showed that E. faecalis EVs considerably increased the expression of NOD2, a cytoplasmic PRR, and that inhibition of NOD2 markedly reduced macrophage M1 polarization induced by E. faecalis EVs. RIPK2 ubiquitination is a major downstream of NOD2. We also observed increased RIPK2 ubiquitination in macrophages treated with E. faecalis EVs, and E. faecalis EV-induced macrophage M1 polarization was notably alleviated by the RIPK2 ubiquitination inhibitor. Our study revealed the potential for EVs to be considered a virulence factor of E. faecalis and found that E. faecalis EVs can promote macrophage M1 polarization via NOD2/RIPK2 signaling. To our knowledge, this is the first report to investigate apical periodontitis development from the perspective of bacterial vesicles and demonstrate the role and mechanism of E. faecalis EVs in macrophage polarization. This study expands our understanding of the pathogenic mechanism of E. faecalis and provides novel insights into the pathogenesis of apical periodontitis.

[Surgical treatment of primary liver cancer:a report of 10 966 cases].

Objective: To summarize the experience of surgical treatment of primary liver cancer. Methods: The clinical data of 10 966 surgically managed cases with primary liver cancer, from January 1986 to December 2019 at Hepatobiliary Center, the First Affiliated Hospital of Nanjing Medical University, were retrospectively analyzed. The life table method was used to calculate the survival rate and postoperative recurrence rate. Log-rank test was used to compare the survival process of different groups, and the Cox regression model was used for multivariate analysis. In addition, 2 884 cases of hepatocellular carcinoma(HCC) with more detailed follow-up data from 2009 to 2019 were selected for survival analysis. Among 2 549 patients treated with hepatectomy, there were 2 107 males and 442 females, with an age of (56.6±11.1) years (range: 20 to 86 years). Among 335 patients treated with liver transplantation, there were 292 males and 43 females, with an age of (51.0±9.7) years (range: 21 to 73 years). The outcomes of hepatectomy versus liver transplantation, anatomic versus non-anatomic hepatectomy were compared, respectively. Results: Of the 10 966 patients with primary liver cancer, 10 331 patients underwent hepatectomy and 635 patients underwent liver transplantation. Patients with liver resection were categorized into three groups: 1986－1995(712 cases), 1996－2008(3 988 cases), 2009‒2019(5 631 cases). The 5-year overall survival rate was 32.9% in the first group(1986－1995). The 5-year overall survival rate of resected primary liver cancer was 51.7% in the third group(2009-2019), among which the 5-year overal survival rates of hepatocellular carcinoma, intrahepatic cholangiocarcinoma and mixed liver cancer were 57.4%, 26.6% and 50.6%, respectively. Further analysis was performed on 2 549 HCC patients with primary hepatectomy. The 1-, 3-, 5-, and 10-year overall survival rates were 88.1%, 71.9%, 60.0%, and 41.0%, respectively, and the perioperative mortality rate was 1.0%. Two hundred and forty-seven HCC patients underwent primary liver transplantation, with 1-, 3-, 5-, and 10-year overall survival rates of 84.0%, 64.8%, 61.9%, and 57.6%, respectively. Eighty-eight HCC patients underwent salvage liver transplantation, with the 1-, 3-, 5-, and 10-year overall survival rates of 86.8%, 65.2%, 52.5%, and 52.5%, respectively. There was no significant difference in survival rates between the two groups with liver transplantation (P>0.05). Comparing the overall survival rates and recurrence rates of primary hepatectomy (2 549 cases) with primary liver transplantation (247 cases), the 1-, 3-, 5-, and 10-year overall survival rates in patients within Milan criteria treated with hepatectomy and transplantation were 96.3%, 87.1%, 76.9%, 54.7%, and 95.4%, 79.4%, 77.4%, 71.7%, respectively (P=0.754). The 1-, 3-, 5-year recurrence rates were 16.3%, 35.9%, 47.6% and 8.1%, 11.7%, 13.9%, respectively(P<0.01). The 1-, 3-, 5-, 10-year overall survival rates in patients with no large vessels invasion beyond the Milan criteria treated with liver resection and transplantation were 87.2%, 65.9%, 53.0%, 33.0% and 87.6%, 71.8%, 71.8%, 69.3%, respectively(P=0.003); the 1-, 3-, 5-year recurrence rate were 39.2%, 57.8%, 69.7% and 29.7%, 36.7%, 36.7%, respectively (P<0.01). The 1-, 3-, 5-, and 10-year overall survival rates in patients with large vessels invasion treated with liver resection and transplantation were 62.1%, 36.1%, 22.2%, 15.0% and 62.9%, 31.8%,19.9%, 0, respectively (P=0.387); the 1-, 3-, 5-year recurrence rates were 61.5%, 74.7%, 80.8% and 59.7%, 82.9%, 87.2%, respectively(P=0.909). Independent prognostic factors for both overall survival and recurrence-free survival rates of HCC patients treated with liver resection included gender, neoadjuvant therapy, symptoms, AST, intraoperative or postoperative blood transfusion, tumor number, tumor size, cirrhosis, macrovascular invasion, microvascular invasion, and pathological differentiation. Propensity score matching analysis of 443 pairs further showed that there was no significant difference in overall survival rate between anatomical liver resection and non-anatomical liver resection(P=0.895), but the recurrence rate of non-anatomical liver resection was higher than that of anatomical liver resection(P=0.035). Conclusions: In the past decade, the overall survival rate of HCC undergoing surgical treatment is significantly higher than before. For HCC patients with good liver function reservation, surgical resection can be performed first, and salvage liver transplantation can be performed after recurrence. The effect of salvage liver transplantation is comparable to that of primary liver transplantation. As for the choice of liver resection approaches, non-anatomical resection can reserve more liver tissue and can be selected as long as the negative margin is guaranteed.

[A clinicopathological classification analysis of ocular mass lesions in 7 910 cases].

Objective: To investigate the anatomical region, histopathological classification and histogensis distribution of ocular mass lesions in South China. Methods: Retrospective cases study. The clinical and pathological data of 7 910 samples with ocular (adnexal) tumors or proliferative lesions which were examined from January 2000 to May 2018 were retrospectively retrieved. The constituent ratios of ocular mass lesions in different anatomical regions and histogenesis have been analyzed. Results: There were 3 445 males and 4 465 females aged from 3 months to 106 years. Classification by anatomical region. Eyelid 4 976 cases (62.9%): benign-pigmented nevus (31.7%, 1 342/4 235), squamous cell papilloma (12.3%, 519/4 235), seborrheic keratosis (9.4%, 396/4 235); malignant-basal cell carcinoma (48.5%, 359/741), sebaceous gland carcinoma (34.4%, 255/741), squamous cell carcinoma (12.3%, 91/741). Ocular surface 1 449 cases (18.3%): benign-pigmented nevus (26.6%, 359/1 348), squamous cell papilloma (12.8%, 173/1 348); malignant-lymphoma (34.7%, 35/101), squamous cell carcinoma (30.7%, 31/101).Orbit 1 485 cases (18.8%): benign-hemangioma (28.5%, 332/1 167), lacrimal gland (duct) cyst(13.2%, 154/1 167); malignant-lymphoma (44.7%, 142/318), adenoid cystic carcinoma (10.1%, 32/318). Classification by histogenesis: epithelial 2 145 cases (27.1%), cutaneous appendages 378 cases (4.8%), cystoid 1 068 cases (13.5%), mesenchymal 748 cases (9.5%), lymph-hematopoietic 225 cases (2.8%), neurogenic 31 cases (0.4%), melanocytic 1 765 cases (22.3%), others 1 550 cases (19.6%). Conclusions: Over the past 18 years, the ocular tumors identified at the Second Affiliated Hospital, Zhejiang University School of Medicine most frequently occur in eyelid and originate from epithelium. The most common types are as followings. Benign lesions: pigmented nevus, squamous cell papilloma are the most common types for eyelid and ocular surface, whereas hemangioma, lacrimal gland (duct) cyst and epidermoid cyst are the most common types for orbit. Malignant cancers: basal cell carcinoma is the most prevalent disease in eyelid, whereas lymphoma occurs more frequently in ocular surface and orbit. (Chin J Ophthalmol, 2019, 55: 847-853).

[Association between miR-146a single nucleotide polymorphism and genetic susceptibility to hepatocellular carcinoma: a meta-analysis].

Objective: To investigate the association between miR-146a single nucleotide polymorphism and genetic susceptibility to hepatocellular carcinoma (HCC). Methods: PubMed, Web of Science, Cochrane Library, Wanfang Data, and Google Scholar were searched for case-control studies on the association between miR-146a single nucleotide polymorphism and genetic susceptibility to HCC published up to October, 2016 in Chinese or English. The Q-statistics test was used to evaluate the heterogeneity of these articles. Results: A total of 18 articles with 5 610 cases and 7 531 controls were included for the meta-analysis. There was no significant association between miR-146a single nucleotide polymorphism and genetic susceptibility to HCC. The odds ratio (OR), 95% confidence interval (95% CI), and P values for the five genetic models were as follows: the allele model C/G (OR = 0.99, 95% CI 0.88-1.06, P = 0.440); the heterozygous model CG/GG (OR = 0.99, 95% CI 0.90-1.10, P = 0.898); the homozygous model CC/GG (OR = 0.91, 95% CI 0.75-1.10, P = 0.314); the dominant model CC+CG/GG (OR = 0.97, 95% CI 0.79-1.19, P = 0.759); the recessive model CG+GG/CC (OR = 1.05, 95% CI 0.94-1.18, P = 0.405). A subgroup analysis of race, source of control population, and Hardy-Weinberg equilibrium were performed in these five genetic models, and miR-146a single nucleotide polymorphism increased the susceptibility to HCC only in the control population-based subgroups of the recessive model CG+GG/CC (OR = 1.20, 95% CI 1.02-1.40, P = 0.024). There was no association between miR-146a rs2910164 polymorphism and susceptibility to HCC in all the other subgroups. A stratified analysis of HBV infection revealed that miR-146a rs2910164 polymorphism increased the risk of HBV-positive HCC (OR = 1.26, 95% CI 1.10-1.49, P = 0.001). Conclusion: There is no significant association between miR-146a rs2910164 polymorphism and the risk of HCC, but miR-146a rs2910164 polymorphism may increase the risk of HBV-positive HCC.

Contributions of polymorphisms in miR146a, miR196a, and miR499 to the development of hepatocellular carcinoma.

Hepatocellular carcinoma is one of the most common malignant tumors worldwide; it is estimated that there were 782,000 new cases in 2012. MicroRNAs (miRNAs) play an important role in carcinogenesis by regulating oncogenes and tumor suppressors. We investigated the role of miR-146a, miR-196a2, and miR-499 polymorphisms in the risk of hepatocellular carcinoma in a Chinese population. Hepatocellular carcinoma patients (175) and healthy controls (302) were recruited between April 2013 and March 2015. Genotype analysis of miR-146a, miR-196a2, and miR-499 polymorphisms was carried out by polymerase chain reaction-restriction fragment length polymorphism. There was a significant difference between the genotype distribution of miR-196a2 in hepatocellular carcinoma patients and controls (X2 = 17.23, P < 0.001). CG and GG miR-146a genotypes significantly elevated the risk of hepatocellular carcinoma compared with the CC genotype, with adjusted ORs (95%CI) of 3.05 (1.07-8.70) and 4.96 (1.64-14.97), respectively. In the recessive model, the CG + GG genotype had a 3.75-fold risk of hepatocellular carcinoma compared with the CC genotype, with an adjusted OR (95%CI) of 3.75 (1.39-10.11). However, no significant association was observed between miR-196a2 and miR-499 variants and risk of hepatocellular carcinoma in the co-dominant, dominant, and recessive models. The miR-146a polymorphism is a G to C substitution that causes a mismatch in the stem-loop of miRNA, which influences how the expression and transcriptional regulation of miRNA affects its target genes. Our study revealed that the GG and CG genotypes of miR-146a increased the risk of hepatocellular carcinoma in the Chinese population.

[Comparison between poly hydroxy acrylic acid and Van-clear replacing the traditional reagents to detect the cervical hTERC genes by adopting FISH technique].

OBJECTIVE: To observe the difference of the human telomeres RNA component (hTERC) genes' amplification in the cervical tissue by applying the environment-friendly fixative poly hydroxy acrylic acid and the transparent dewaxing solution Van-clear separately or jointly to replace the traditional fixative 4% (volume fraction) neutral buffered formalin and the conventional transparent dewaxing solution xylene in the use of fluorescence in situ hybridization (FISH) for detection. METHODS: In the study, 255 cases of cervical tissue specimens submitted by the Department of Gynecology in Zhongshan Boai Hosipital were collected from Mar. 2013 to Apr. 2015. Four samples were taken from the same lesion site. All the cases were divided into 4 groups and named group A, B, C, and D. Group A used 4% neutral buffered formalin fixed and xylene dewaxing to make slices. Group B used poly hydroxy acrylic fixed and xylene dewaxing to make slices. Group C used 4% neutral buffered formalin fixed and Van-clear transparent to make slices. Group D used poly hydroxy acrylic fixed and Van-clear transparent dewaxing to make slices. The amplification of hTERC genes in the four groups of cervical specimens was also detected by FISH technique. RESULTS: When the hTERC genes were detected by FISH method under the fluorescence microscope, it was obvious that the tissue profile and the background of group A, B, C and D were all clear. The probe was fixed in the accurate position so that the bright red or green fluorescence signals were easily found in these four groups. Compared with the positive rate of group A, there was no statistical significance in that of group B, C and D (P>0.05). At the same time, the coincidence rate of the FISH results was high, which showed that the new environment-friendly reagent had no significant difference in the detection of cervical hTERC genes by FISH technique. CONCLUSION: It is possible for the environment-friendly reagent poly hydroxy acrylic acid and Van-clear to replace 4% neutral buffered formalin and xylene separately or jointly to detect the cervical hTERC genes by adopting FISH technique.

Molecular cloning, sequence characterization of a novel pepper gene NADP-ICDH and its effect on cytoplasmic male sterility.

NADP-dependent isocitrate dehydrogenase (NADP-ICDH) is an important enzyme involved in energy metabolism. The complete coding sequence of the pepper (Capsicum annuum) NADP-ICDH gene was amplified using a reverse transcriptase PCR based on the conserved sequence information of the tomato and other Solanaceae plants and known highly homologous pepper ESTs. Nucleotide sequence analysis revealed that the pepper NADP-ICDH gene encodes a protein of 415 amino acids that has high homology with the proteins of seven species, Solanum tuberosum (100%), Citrus limon (98%), Daucus carota (98%), Nicotiana tabacum (98%), Vitis vinifera (99%), Arabidopsis thaliana (97%), and Oryza sativa (98%). Tissue expression analysis demonstrated that the pepper NADP-ICDH gene is over expressed in flower, pericarp and seed, moderately in placenta, weakly in stem and leaf, hardly expressed in root. At the abortion stages, activities and expression levels of NADP-ICDH in anthers of a sterile line were strongly reduced, while those in an F(1) hybrid remained normal. Activities and expression levels of NADP-ICDH were too low to maintain balanced energy metabolism in the sterile line, which indicated that stable transcripts of NADP-ICDH are necessary to maintain energy metabolism at a normal level. When the restorer gene was transferred to the cytoplasmic male sterile line, activities and expression level of NADP-ICDH were regulated by the restorer gene and became stable. The restorer gene likely plays an important role in keeping the balance of the energy metabolism within normal levels during microspore development.

Vg1 orthology in the direct developing frog, Syrrhophus cystignathoides campi.

Syrrhophus cystignathoides campi is a direct developing frog species that matures without passing through a larval (tadpole) stage. We have cloned and sequenced the Syrrhophus cDNA orthologous to the Xenopus Vg1 cDNA. The Syrrhophus Vg1 (sVg1) cDNA spans 1323 nucleotides and encodes a predicted protein of 345 amino acids which is 81% identical at its carboxyl terminal end to Xenopus Vg1. In addition, it contains seven conserved cysteine residues present in all Vg1 related proteins. Despite this high degree of similarity it is apparently missing a conserved N-linked glycosylation site and has an altered proteolytic processing sequence. Interestingly it is also missing a nine nucleotide sequence in its 3' UTR believed to be important for mRNA localization in Xenopus and Drosophila. These sequence variations could alter the functional expression and localization of the protein.

[On the difference of cardiovascular effects between caudal ventrolateral medulla pressor area (cVMP) and rostrolateral medulla pressor area (rVMP)].

In 56 urethane anesthetized Wistar rats, bilateral microinjection of glutamate (L-glu) was used to observe the difference of cardiovascular effects between caudal ventrolateral medulla pressor area (cVMP) and rostral ventrolateral medulla pressor area (rVMP). The results showed that the pressor effect of cVMP was weaker than that of rVMP and was not accampanied by responses in heart rate. In the latter case, an increase of heart rate was involved. The baroreflex was inhibited when rVMP was activated by L-glu but facilitated when cVMP was activated. The above results suggest that the pathway and functions of the cardiovascular effects of rVMP are different from those of cVMP.

[Endoscopic injection sclerotherapy for esophageal varices: studies on methodology and complication].

From November 1985 to February 1991, sixty patients were randomized to three groups of intravariceal sclerotherapy: (1) many punctures of low quantity sclerosant, (2) one puncture of large quantity sclerosant, and (3) one puncture of large quantity sclerosant with transendoscopic balloon. The early effects and complications were investigated. Varices eradication was reached 91.2% in group 1, significantly higher than group 2 (58.3%) (P < 0.05), similar to group 3(89.9%). However, balloon group (group 3) required shorter duration than group 1 (12.6 vs. 21.7 days) (P < 0.05). There were no significant differences in complications, but all 6 esophageal stenosis were in group 1, recurrent bleeding was 11.4% in group 1.35.7% in group 2 and 0 in group 3 during sclerotherapy sessions. Further more, we found though attempted to inject into variceal veins, accurate intravariceal injection reached only 46.8% in accordance with venographic findings. We conclude that sclerotherapy with transendoscopic balloon seems to be more simple, safer, and required short time to produce successful variceal sclerosis.

The thromboxane A2 mimetic U46619 worsens canine myocardial hypoperfusion during exercise in the presence of a coronary artery stenosis.

OBJECTIVE: The aim was to test the hypothesis that thromboxane A2 can cause vasoconstriction of coronary resistance vessels during exercise in hypoperfused regions of myocardium distal to an arterial stenosis. METHODS: Eight adult mongrel dogs were studied. Chronically instrumented animals with a left circumflex coronary artery Doppler flow meter, hydraulic occluder, and indwelling catheter underwent treadmill exercise at heart rates of 190-200 beats.min-1. Myocardial blood flow was measured with microspheres during unimpeded arterial inflow and in the presence of a coronary stenosis which decreased distal pressure to 42-45 mm Hg. Measurements were repeated during infusion of the thromboxane A2 analogue, U46619. RESULTS: When the occluder was partially inflated to produce a stenosis, blood flow in the region perfused by the stenotic artery was 58 (SEM 6)% of flow in the normally perfused region (p less than 0.01). U46619 (0.01 microgram.kg-1.min-1) caused a further 21 (7)% decrease in blood flow in the region perfused by the stenotic artery (p less than 0.05). The vasoconstriction produced by U46619 was uniform across the left ventricular wall from epicardium to endocardium. U46619 did not significantly decrease myocardial blood flow in the absence of a coronary stenosis. CONCLUSIONS: Even during hypoperfusion produced by a flow limiting arterial stenosis, the coronary resistance vessels remain responsive to the vasoconstrictor effect of thromboxane A2. Liberation of thromboxane A2 during platelet activation at the site of a proximal coronary stenosis may worsen myocardial hypoperfusion by causing vasoconstriction of the distal resistance vessels.

Effect of serotonin and thromboxane A2 on blood flow through moderately well developed coronary collateral vessels.

This study was performed to determine whether thromboxane A2 (as the analogue U46619) and serotonin can cause vasoconstriction of moderately well developed coronary collateral vessels. Studies were carried out in seven adult mongrel dogs 2 to 4 months after embolic occlusion of the left anterior descending coronary artery had been performed to stimulate collateral vessel growth. At the time of study this artery was cannulated to determine interarterial collateral flow from measurements of retrograde blood flow. Radioactive microspheres were administered during retrograde flow collection to determine continuing tissue flow for evaluation of microvascular collateral communications. Serotonin (50 micrograms/min) resulted in a 48 +/- 11% decrease in retrograde flow (p less than 0.01), with a 36 +/- 10% decrease in total collateral blood flow (p less than 0.02). Infusion of U46619 (0.01 microgram/kg per min) caused a 38 +/- 13% decrease in retrograde blood flow (p less than 0.01), with a 34 +/- 13% decrease in total collateral flow (p less than 0.05). Serotonin caused a significant increase in tissue flow to the subepicardium of the collateral-dependent region, whereas U46619 caused no change in tissue blood flow. These data demonstrate that both serotonin and thromboxane A2 can cause vasoconstriction of interarterial coronary collateral vessels. The findings suggest that platelet activation in coronary arteries from which collateral vessels originate has potential for causing collateral vasoconstriction, thereby compromising blood flow to the dependent myocardium.

Effect of alpha-adrenergic blockade with prazosin on large coronary diameter during exercise.

BACKGROUND: Exercise-induced dilation of coronary resistance vessels is limited by alpha-adrenergic mechanisms. However, the effect of alpha-adrenergic mechanisms on large coronary arteries during exercise is not known. METHODS AND RESULTS: In the present study, sonomicrometry was used to measure circumflex coronary arterial diameter during treadmill exercise before and after alpha 1-adrenergic blockade with prazosin in eight instrumented dogs. Before infusion of prazosin, exercise caused a fall in coronary vascular resistance (2.1 +/- 0.4 to 1.6 +/- 0.2 units, p less than 0.05) and dilation of the circumflex coronary artery (4.66 +/- 0.37 to 4.79 +/- 0.34 mm, p less than 0.05). Intracoronary infusion of prazosin during exercise caused a further decrease in coronary vascular resistance (1.6 +/- 0.2 to 1.4 +/- 0.2 units, p less than 0.05) and a further increase in circumflex coronary arterial diameter (4.79 +/- 0.34 to 4.83 +/- 0.34 mm, p less than 0.05). Intracoronary infusion of vehicle without prazosin during exercise did not cause a further decrease in coronary vascular resistance or increase in coronary diameter. Prazosin caused no significant increase in heart rate, aortic pressure, or coronary blood flow. Therefore, both small coronary resistance vessels and large epicardial coronary arteries dilated during exercise and dilated further after alpha-adrenergic blockade. CONCLUSIONS: This finding indicates that alpha 1-adrenergic activity during exercise limits dilation of both large and small coronary arteries.

Coronary vasodilator reserve in ischemic myocardium of the exercising dog.

BACKGROUND: Previous work has reported that coronary vasodilator reserve may persist in myocardium rendered ischemic by hypoperfusion. This study investigated the presence and extent of residual coronary vasomotor tone in myocardial regions made acutely ischemic by a flow-limiting coronary stenosis during exercise. METHODS AND RESULTS: Studies were done in chronically instrumented dogs undergoing treadmill exercise in the presence of a coronary stenosis that decreased distal left circumflex coronary artery perfusion pressure to approximately 40 mm Hg. Measurements of myocardial blood flow were made with radioactive microspheres during exercise (6.5 km/hr, 6% grade) before and during intracoronary infusion of the potent coronary vasodilator adenosine (40 micrograms/kg/min). Distal coronary perfusion pressure was held equal before and during intracoronary adenosine infusion (43 +/- 5 versus 42 +/- 5 mm Hg) by adjusting the hydraulic coronary occluder. During exercise in the presence of a coronary stenosis, myocardial blood flow (milliliter per minute per gram) was significantly reduced in all layers of the ischemic posterior region compared with the nonischemic anterior region. During intracoronary adenosine infusion, with no change in coronary perfusion pressure, myocardial blood flow was significantly increased compared with preadenosine flows for both the subendocardial layer flow (1.03 +/- 0.74 versus 0.66 +/- 0.50; p less than 0.05) and mean transmural flow (1.54 +/- 0.59 versus 1.16 +/- 0.36; p less than 0.05). In the presence of a coronary stenosis, regional myocardial segment shortening in the ischemic region during exercise fell significantly to 49 +/- 8% of shortening in the absence of a coronary stenosis but improved modestly during adenosine infusion (65 +/- 7 versus 49 +/- 8%; p less than 0.05). CONCLUSIONS: These results indicate that adenosine-responsive coronary vasodilator reserve persists during exercise-induced myocardial ischemia and suggest that residual microvascular vasoconstrictor tone may affect the extent of myocardial hypoperfusion occurring consequent to a flow-limiting coronary stenosis.

Vasoconstriction of canine coronary collateral vessels with vasopressin limits blood flow to collateral-dependent myocardium during exercise.

This study was performed to test the hypothesis that active constriction of coronary collateral vessels can worsen hypoperfusion of collateral-dependent myocardium during exercise. Studies were performed in seven adult mongrel dogs in which intermittent followed by permanent occlusion of the left circumflex coronary artery produced an area of collateral-dependent myocardium without gross evidence of infarct. Myocardial blood flow was determined with microspheres while measurement of aortic and distal coronary pressures allowed calculation of collateral and small vessel resistance at rest and during treadmill exercise. The ability of collateral vessel constriction to limit blood flow was assessed by infusion of vasopressin during exercise. During control conditions, blood flow in the collateral zone underwent a subnormal increase during exercise in comparison with the normal zone (1.74 +/- 0.27 versus 2.50 +/- 0.40 ml/min/g, respectively, p less than 0.05). Infusion of vasopressin in a dose that caused no change in normal zone flow (0.01 microgram/kg/min i.v.) produced a 30 +/- 5% further decrease in flow to the collateral zone (p less than 0.01). This decrease in collateral zone flow resulted from a 48 +/- 14% increase in transcollateral resistance in response to vasopressin infusion (p less than 0.01), as well as a 40 +/- 9% increase in small vessel resistance in the collateral zone (p less than 0.01). These data demonstrate that active constriction of both collateral vessels and coronary resistance vessels can contribute to hypoperfusion of collateral-dependent myocardium during exercise.

Effect of alpha 1-adrenergic blockade on myocardial blood flow during exercise after myocardial infarction.

The effect of alpha 1-adrenergic blockade with prazosin on myocardial blood flow at rest and during two levels of treadmill exercise was assessed in 16 chronically instrumented dogs 9-14 days after myocardial infarction had been produced by occlusion of the left circumflex coronary artery. During resting conditions prazosin did not alter mean myocardial blood flow or the subendocardial-to-subepicardial flow ratio in either normally perfused or collateral-dependent myocardium. However, during exercise at comparable external work loads and comparable rate-pressure products, prazosin significantly increased blood flow to normally perfused (27% increase at the second level of exercise, P less than 0.001) and collateral-dependent myocardium (35% increase at the second level of exercise, P less than 0.001) compared with control. In addition, prazosin caused a small but significant decrease in the subendocardial-to-subepicardial flow ratio in both normal (1.27 +/- 0.04 to 1.19 +/- 0.04; P less than 0.01) and collateral-dependent myocardium (0.57 +/- 0.11 to 0.52 +/- 0.11; P less than 0.01) compared with control, reflecting a disproportionally greater increase in subepicardial flow in response to alpha 1-adrenergic blockade. These data demonstrate that alpha 1-adrenergic vasoconstriction inhibits coronary vasodilation during exercise, even in areas of collateral-dependent myocardium relatively early after coronary artery occlusion.

Effects of amiodarone with and without polysorbate 80 on myocardial oxygen consumption and coronary blood flow during treadmill exercise in the dog.

Since amiodarone has been reported to possess antianginal activity, this study examined the effects of amiodarone on coronary blood flow and myocardial oxygen consumption during exercise. Studies were performed in 14 chronically instrumented dogs trained to run on a motor-driven treadmill. Left circumflex coronary artery blood flow was measured with an electromagnetic flowmeter while aortic and coronary sinus catheters allowed measurement of myocardial oxygen extraction. During control conditions, graded exercise resulted in progressive increases in heart rate, aortic pressure, and coronary blood flow. Two preparations of amiodarone, 5 mg/kg, one dissolved in sterile water and the other in 10% polysorbate 80, were given intravenously to separate groups of dogs. Amiodarone in sterile water caused no hemodynamic changes at rest. However, the increase in heart rate during exercise was blunted after amiodarone, so that heart rate during the heaviest level of exercise was significantly less than during control exercise. Coronary blood flow and myocardial oxygen consumption were unchanged. Amiodarone with polysorbate 80 also blunted the increase in heart rate during exercise, but in addition caused a significant decrease in aortic pressure both at rest and during exercise. Myocardial oxygen consumption and coronary blood flow were significantly decreased after administration of amiodarone with polysorbate 80 at rest and during all exercise levels. Amiodarone with or without polysorbate 80 did not change myocardial oxygen extraction. These data demonstrate that amiodarone exerts a negative chronotropic effect during exercise. However, the decreased arterial pressure and myocardial oxygen consumption were not due to amiodarone, but was seen only with the combination of amiodarone dissolved in polysorbate 80.

[Characteristics of central acute resetting of high threshold baroreflex in rabbit's aortic nerves].

Experiments were performed on 37 urethane-anesthetized rabbits. The aortic nerves, carotid sinus nerves and vagus nerves were cut, MAP and renal sympathetic nerve activity (RSNA) were recorded. The conditional stimulation CSc (0.5 ms, 10 Hz, 4-6V, 5 min) was used to mimic the information of baroreflex non-medullated afferent fibers responding to acute increase of BP. Test stimulation TSa (0.02 ms, 0-80 Hz/30 s, 4-6V) and TSc (0.5 ms, 0-20 Hz/30s, 4-6V) was used to examine the responses of baroreflex A- and C-fibers. After CSc at 1 min the reflex MAP and RSNA of TSc was attenuated at 45.5% (P less than 0.01) and 10.6% (P less than 0.05), the MAP response of TSa was attenuated at 32.1% (P less than 0.05), but the RSNA response was not. From the further investigation it is concluded that the characteristics of central acute resetting are dependent on the components of baroreflex afferent fibers. The reflex responses are attenuated mainly by correspondent afferent components.

Adrenergic vasoconstriction limits coronary blood flow during exercise in hypertrophied left ventricle.

This study was carried out to test the hypothesis that alpha-adrenergic vasoconstriction limits coronary blood flow (CBF) during exercise in the chronically pressure overloaded, hypertrophied left ventricle. Studies were performed in dogs in which left ventricular hypertrophy had been produced by banding the ascending aorta at 9 wk of age. Left circumflex coronary artery blood flow and myocardial O2 consumption (MVO2) were examined at rest and during treadmill exercise during control conditions, after selective alpha 1-adrenergic blockade with prazosin, and after nonselective alpha-adrenergic blockade with phentolamine. All studies were performed after beta-adrenergic blockade with propranolol. During control conditions CBF and MVO2 increased progressively during exercise, while coronary sinus O2 tension decreased. Neither prazosin nor phentolamine altered CBF at rest but, in comparison with control measurements, both agents significantly increased CBF during exercise and abolished the decrease in coronary sinus O2 tension that normally occurred during exercise. Both prazosin and phentolamine caused similar significant increases of MVO2 relative to the heart rate times systolic left ventricular pressure during exercise, indicating that the increased CBF produced by these agents enhanced MVO2. Similar findings after prazosin and phentolamine indicate that adrenergic restraint of CBF during exercise resulted principally from alpha 1-adrenergic vasoconstrictions with little additional contribution from postjunctional alpha 2-adrenergic mechanisms.

Effect of pinacidil on myocardial blood flow in the chronically pressure overloaded hypertrophied left ventricle.

This study examined the effect of pinacidil on the transmural distribution of myocardial blood flow in the chronically pressure overloaded hypertrophied left ventricle. Studies were performed in six dogs in which banding of the ascending aorta had resulted in an 88% increase in left ventricular mass, as well as in six normal control animals. Two doses of pinacidil were administered to decrease mean arterial pressure by approximately 10 mm Hg (low dose) and 20 mm Hg (high dose). Animals with hypertrophy required significantly smaller drug doses to achieve the desired reductions in arterial pressure. During control conditions mean myocardial blood flow was significantly higher in animals with hypertrophy (1.90 +/- 0.21 ml/min/g) than in normal animals (1.12 +/- 0.08 ml/min/g; p less than 0.05). Subendocardial flow (endo) exceeded subepicardial flow (epi) in normal dogs during control conditions (endo/epi = 1.41 +/- 0.13), but not in animals with hypertrophy (endo/epi = 1.06 +/- 0.06; p less than 0.05). Pinacidil caused coronary vasodilation with similar relative increases in blood flow in both normal and hypertrophied hearts, so that after pinacidil, absolute blood flow rates remained higher than normal in animals with hypertrophy. Pinacidil caused a redistribution of blood flow away from the subendocardium in normal hearts (endo/epi = 0.90 +/- 0.11 during high-dose pinacidil) and in hearts with hypertrophy (endo/epi = 0.81 +/- 0.13 during high-dose pinacidil). The endo/epi ratios during high-dose pinacidil were not significantly different between the two groups. This study demonstrates that pinacidil is a potent coronary vasodilator in both normal and hypertrophied hearts.(ABSTRACT TRUNCATED AT 250 WORDS)