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1.
Zhonghua Er Ke Za Zhi ; 59(4): 286-293, 2021 Apr 02.
Artigo em Chinês | MEDLINE | ID: mdl-33775047

RESUMO

Objective: To establish a disease risk prediction model for the newborn screening system of inherited metabolic diseases by artificial intelligence technology. Methods: This was a retrospectively study. Newborn screening data (n=5 907 547) from February 2010 to May 2019 from 31 hospitals in China and verified data (n=3 028) from 34 hospitals of the same period were collected to establish the artificial intelligence model for the prediction of inherited metabolic diseases in neonates. The validity of the artificial intelligence disease risk prediction model was verified by 360 814 newborns' screening data from January 2018 to September 2018 through a single-blind experiment. The effectiveness of the artificial intelligence disease risk prediction model was verified by comparing the detection rate of clinically confirmed cases, the positive rate of initial screening and the positive predictive value between the clinicians and the artificial intelligence prediction model of inherited metabolic diseases. Results: A total of 3 665 697 newborns' screening data were collected including 3 019 cases' positive data to establish the 16 artificial intelligence models for 32 inherited metabolic diseases. The single-blind experiment (n=360 814) showed that 45 clinically diagnosed infants were detected by both artificial intelligence model and clinicians. A total of 2 684 cases were positive in tandem mass spectrometry screening and 1 694 cases were with high risk in artificial intelligence prediction model of inherited metabolic diseases, with the positive rates of tandem 0.74% (2 684/360 814)and 0.46% (1 694/360 814), respectively. Compared to clinicians, the positive rate of newborns was reduced by 36.89% (990/2 684) after the application of the artificial intelligence model, and the positive predictive values of clinicians and artificial intelligence prediction model of inherited metabolic diseases were 1.68% (45/2 684) and 2.66% (45/1 694) respectively. Conclusion: An accurate, fast, and the lower false positive rate auxiliary diagnosis system for neonatal inherited metabolic diseases by artificial intelligence technology has been established, which may have an important clinical value.


Assuntos
Doenças Metabólicas , Triagem Neonatal , Inteligência Artificial , China , Humanos , Lactente , Recém-Nascido , Estudos Retrospectivos , Método Simples-Cego , Tecnologia
2.
Zhonghua Yi Xue Za Zhi ; 100(42): 3338-3341, 2020 Nov 17.
Artigo em Chinês | MEDLINE | ID: mdl-33202498

RESUMO

Objective: To investigate the incidence of preterm birth in Guangxi Zhuang Autonomous Region and explore the related factors and their combined effects. Methods: The study subjects were women giving birth to live babies at the monitoring points of critical maternal hospital monitoring system in Guangxi Zhuang Autonomous Region from January 1, 2017 to December 31, 2019. The data of general characteristics (age and marital status), pregnancies (parity, number of previous cesarean delivery, the number of prenatal check and number of fetuses in this pregnancy) and disease conditions (placenta previa, placental abruption, hypertension, diabetes, anemia, and heart disease) were collected, and the incidence of preterm birth were calculated according to the definition of preterm birth set by WHO and China, respectively. Logistic regression model was used to explore the factors associated with premature birth and their combined effects. Results: According to definitions of WHO and China, the cumulative incidence of preterm birth in Guangxi from 2017 to 2019 was 7.45% (16 819/225 727) and 7.34% (16 559/225 727), respectively. Advanced age [≤34 years old as reference, OR (95%CI) of 35-39 and ≥40 years old were 1.36 (1.30-1.42) and 1.61 (1.50-1.74), respectively], unmarried (including divorced or widowed) [OR (95%CI): 1.28 (1.17-1.40)], primiparae [OR (95%CI): 1.34 (1.29-1.40)], previous cesarean section [no previous cesarean section as reference, OR (95%CI) of 1 and ≥2 times of previous cesarean section were 1.30 (1.24-1.36) and 1.85 (1.65-2.08), respectively], antenatal examination<8 [OR (95%CI): 2.72 (2.62-2.81)], multiple pregnancies [OR (95%CI): 15.00 (14.01-16.06)], placenta previa [OR (95%CI): 6.90 (6.35-7.50)], placental abruption [OR (95%CI): 8.18 (7.36-9.10)], gestational hypertension [OR (95%CI): 2.29 (2.17-2.42)], gestational diabetes mellitus [OR (95%CI): 1.43 (1.37-1.49)], anemia [OR (95%CI): 1.10 (1.07-1.14)], and heart diseases [OR (95%CI): 2.98(2.43-3.65)] were all positively correlated with preterm birth. The risk of preterm birth in pregnant women exposed to 1, 2, 3, 4, 5, 6 and ≥7 preterm birth related factors was 1.51, 2.29, 4.49, 9.69, 20.87, 46.88 and 192.11 times that of non-exposed women, respectively (all P values<0.001). Conclusion: Preterm birth is associated with maternal general characteristics, pregnancy and disease status, and the combined effect of preterm birth related factors significantly increases the risk of preterm birth.


Assuntos
Placenta Prévia , Nascimento Prematuro , Cesárea , China/epidemiologia , Feminino , Humanos , Recém-Nascido , Gravidez , Nascimento Prematuro/epidemiologia , Estudos Retrospectivos , Fatores de Risco
3.
Zhonghua Yu Fang Yi Xue Za Zhi ; 53(12): 1259-1264, 2019 Dec 06.
Artigo em Chinês | MEDLINE | ID: mdl-31795583

RESUMO

Objective: To investigate the distribution and related factors of birth weight of live births and full-term infants in Guangxi Zhuang Autonomous Region of China. Methods: Based on Guangxi women and children information system from 2016 to 2018, a large real-time database about maternal and live-birth information was established. It covered 1 712 midwifery institutions in Guangxi. A total of 2 394 240 cases of live births were collected and 2 243 129 cases of which were full-term infants. The multivariate logistic regression model was used to analyze the related factors of low birth weight. Results: The birth weight of 2 394 240 live births, (3 123.49±461.08) g, in Guangxi was approximately normal distribution with a peak distribution to the left. The incidence of low birth weight was 8.05%, and the incidence of macrosomia was 2.07%. The incidence of low birth weight was 10.92% for the puerpera with body mass index (BMI, kg/m(2)) <18.5, 16.82% for the puerpera with height <145 cm, 8.92% for the puerpera with age <20 years old, 7.67% for the puerpera with age ≥35 years old, and 54.65% for the puerpera with premature birth. The birth weight of 2 243 129 full-term infants, (3 176.01±400.78) g, was approximately normal distribution with a peak distribution to the right. The incidence of low birth weight was 2.97%, and the incidence of macrosomia was 2.19%. The incidence of low birth weight was 4.73% for puerpera with BMI<18.5, 8.17% for puerpera with height<145 cm, 4.83% for puerpera with age <20 years old, and 3.05% for puerpera with age ≥35 years old. The risks of low birth weight [OR (95%CI) value] of pregnant women aged <20, 25-29 and 30-34 years old were 1.31 (1.28-1.35), 0.88 (0.86-0.90) and 0.89 (0.87-0.91) times of those aged ≥35 years old. The risks of low birth weight [OR (95%CI) value] of pregnancy BMI <18.5 and 18.5-23.9 kg/m(2) group were 1.98 (1.94-2.03) and 1.20 (1.18-1.23) times of those pregnancy BMI ≥24 kg/m(2). The risks of low birth weight [OR (95%CI) value] of pregnant women's height (cm)<145, 145-154, 155-159 and 160-164 cm were 4.67 (4.39-4.97), 2.36 (2.29-2.44), 1.58 (1.53-1.63) and 1.22 (1.18-1.26) times of those heights ≥165 cm group. The risks of low birth weight [OR (95%CI) value] of pregnant women's gestational age <28, 28-31 and 32-36 years old were 136.65 (124.33-150.20), 1 704.37 (1 509.02-1 925.02) and 33.45 (32.98-33.94) times of those gestational age ≥37 years old. Conclusion: The incidence of low birth weight of live births was higher in Guangxi from 2016 to 2018. There is a higher risk of low birth weight for younger, older, low height, low BMI and preterm women in Guangxi from 2016 to 2018.


Assuntos
Peso ao Nascer , Nascido Vivo , Nascimento Prematuro/epidemiologia , Adulto , China/epidemiologia , Feminino , Idade Gestacional , Humanos , Recém-Nascido de Baixo Peso , Recém-Nascido , Recém-Nascido Prematuro , Gravidez , Fatores de Risco , Adulto Jovem
4.
Zhonghua Fu Chan Ke Za Zhi ; 54(8): 516-521, 2019 Aug 25.
Artigo em Chinês | MEDLINE | ID: mdl-31461807

RESUMO

Objective: To investigate the factors associated with the success rate of external cephalic version (ECV) for singleton and non-cephalic presentation pregnancies in the third trimester. Methods: A retrospective study of ECV among singleton and non-cephalic presentation pregnant women in 36-40 weeks of gestation at Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region from January 2016 to June 2018 was analyzed. Results: (1) Totally, 251 cases of 358 pregnant women who underwent ECV were successful, with a total success rate of 70.1% (251/358). The success rate of multipara was 79.1% (129/163), while 62.6% (122/195) in primipara (P<0.01). The total vaginal delivery rate was 52.2% (187/358), the vaginal delivery rate of multipara was 61.3% (100/163), while 44.6% (87/195) in primipara (P<0.01). (2) Spontaneous reversion occurred in 7.6%(19/251) of ECV successful women, the rate of reversion of multipara was 10.9% (14/129), higher than that of the primipara [4.1% (5/122); P<0.01]. (3) Among the 232 pregnant women who did not reverted after successful ECV, 187 cases of successful vaginal delivery, the vaginal delivery rate was 80.6% (187/232); the vaginal delivery rate of the multipara was 87.0%(100/115), which was higher than that of the primipara [74.4%(87/117); P<0.01]. (4) The variables significantly associated with ECV success were parity, type of breech, whether fetal presentation was in pelvic or not (all P<0.05). The complication rate was 2.2% (8/358), among which the incidence of fetal distress, placental abruption and transient fetal heart abnormalities were 0.6% (2/358), 0.3% (1/358) and 1.4% (5/358) respectively. Conclusion: By close monitoring, ECV is a safe and effective procedure in selected appropriate cases, and worthy of clinical application.


Assuntos
Apresentação Pélvica , Parto Obstétrico/estatística & dados numéricos , Terceiro Trimestre da Gravidez , Versão Fetal/métodos , Criança , China/epidemiologia , Feminino , Humanos , Complicações do Trabalho de Parto/etiologia , Gravidez , Resultado da Gravidez , Estudos Retrospectivos
5.
Eur Rev Med Pharmacol Sci ; 20(9): 1720-4, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27212162

RESUMO

OBJECTIVE: The purpose of this study was to investigate the expression of lncRNA SNHG15 and its prognostic value in hepatocellular carcinoma (HCC). PATIENTS AND METHODS: Expression levels of lncRNA SNHG15 in 152 pairs of HCC tissues and adjacent normal tissues were detected by quantitative real-time PCR. Associations between clinicopathological parameters and lncRNA SNHG15 expression were evaluated using chi-square tests. The overall survival was analyzed by log-rank test, and survival curves were plotted according to Kaplan-Meier. Univariate and multivariate Cox regression analyses were conducted to determine whether lncRNA SNHG15 was an independent predictor of survival. RESULTS: The lncRNA SNHG15 expression was significantly upregulated in tumor tissues compared with that in adjacent non-tumor tissues (p < 0.01). It is also proved that lncRNA SNHG15 expression was associated with histological grade (p = 0.000), TNM stage (p = 0.015), and vein invasion (p = 0.000). In addition, Kaplan-Meier analysis showed that increased LncRNA SNHG15 expression was associated with poor overall survival of patients (p = 0.0011). Moreover, the results of the multivariate analysis showed that high lncRNA SNHG15 expression was a significant independent predictor of poor survival in HCC (p < 0.05). CONCLUSIONS: Our findings suggest that lncRNA SNHG15 may serve as an efficient clinical biomarker and a therapeutic target for HCC patients.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , RNA Longo não Codificante/genética , Biomarcadores Tumorais/genética , Humanos , Prognóstico , Modelos de Riscos Proporcionais
6.
J Neurosurg Sci ; 57(1): 69-74, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23584222

RESUMO

AIM: The flexible artificial disc may create a system with a biomimetic structure that has the potential to tolerate dynamic motion in a way similar to a normal intervertebral disc over a long period. The objective was to evaluate the mechanical feasibility and clinical and radiological findings with a mono-unit and flexible artificial disc at intermediate-term follow-up. METHODS: Fifty-six patients with degenerative disc disease were selected to participate in the study. They underwent discectomy with a flexible artificial disc with a mean follow-up period of 24.8 months. Outcomes were evaluated with the visual analogue scale (VAS) and Oswestry Disability Index (ODI). Mechanical endurance was evaluated by a dynamic testing. RESULTS: Fifty one-levels and six bi-levels were included in the study (average age 41.8 years). VAS improved from 6.8 ± 2.2 to 1.5 ± 1.7 (P<0.05) and ODI improved from 43.1 ± 10.4 to 18.2 ± 10.2 (P<0.05). Disc height before mechanical testing was 8.9 mm, and decreased to 8.4 mm after six million cycles with no mechanical failure. CONCLUSION: Our results indicate that flexible and mono-unit cervical disc provides favorable mechanical performance and clinical outcomes for at least a relatively intermediate-term follow up period. It is indicated that the flexible cervical disc maintains mobility at the level of the prosthesis that is comparable with preoperative ranges of motion. Further evaluation will be completed once long-term results have been obtained.


Assuntos
Artroplastia/normas , Vértebras Cervicais/cirurgia , Degeneração do Disco Intervertebral/cirurgia , Próteses e Implantes/normas , Implantação de Prótese/normas , Adulto , Vértebras Cervicais/diagnóstico por imagem , Vértebras Cervicais/patologia , Avaliação da Deficiência , Seguimentos , Humanos , Degeneração do Disco Intervertebral/diagnóstico por imagem , Masculino , Pessoa de Meia-Idade , Período Pós-Operatório , Radiografia , Amplitude de Movimento Articular/fisiologia , Índice de Gravidade de Doença , Fatores de Tempo , Resultado do Tratamento , Adulto Jovem
7.
Poult Sci ; 90(5): 1080-7, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21489958

RESUMO

The purpose of this study was to optimize the thermal conditions for processing hatchery waste eggs (HWE) into rich feedstuff with lower electricity consumption by using response surface methodology. In the study, the effects of processing temperature and time on HWE meal (HWEM) quality and production were evaluated. As the results indicate, optimization was obtained when the processing lasted for 23 h at the fixed temperature of 65°C, resulting in higher protein digestibility in vitro (89.6%) and DM (88.5%) content of HWEM with lower electricity consumption (82.4 kWh/60 kg of HWE). No significant differences existed between the quality values predicted by mathematical formulae and those obtained through practical analyses in DM (87 vs. 88.5%), CP (39.2 vs. 38.3%), protein digestibility in vitro (90.7 vs. 89.6%), and electricity consumed (80.8 vs. 82.4 kWh/60 kg of HWE). Furthermore, the product derived from the optimized processing conditions had better biosecurity; Salmonella spp. were not found and Escherichia coli levels were substantially reduced (from 10(7) to 10(4) cfu/g). In summary, HWEM of superior quality can be produced when the processing conditions optimized in the current research are utilized.


Assuntos
Ração Animal/análise , Temperatura Alta , Óvulo , Agricultura , Animais , Galinhas , Fatores de Tempo , Resíduos
8.
Animal ; 5(10): 1506-14, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22440340

RESUMO

Two experiments were conducted to investigate the requirement for dietary crude protein (CP) in growing blue-breasted quail (BBQ). In Experiment 1, 300 1-day-old quails were randomly assigned to 10 groups according to a 2×5 factorial arrangement of treatments with two metabolisable energy (ME) levels (12.13 and 13.39 MJ/kg) and five CP concentrations (160, 190, 220, 250 and 280 g/kg) for 8 weeks. In Experiment 2, 300 1-day-old quails were subjected to a different factorial arrangement of treatments with two ME levels (11.51 and 12.13 MJ/kg) and five CP concentrations (210, 220, 230, 240 and 250 g/kg) for 28 days. Experiment 1 revealed that an interaction existed in weight gain between ME and CP levels in weeks 1 to 4. In both ME groups, quails receiving CP of 160 g/kg showed the least weight gains (P<0.05). No differences (P>0.05) existed in weight gain between the ME groups in which quails ingested CP of 250 and 280 g/kg, whereas quails consuming CP of 220 g/kg with an ME of 13.39 MJ/kg had smaller weight gain than did those ingesting higher CP concentrations (P<0.05). Of main effects for weeks 1-4, quails treated with an ME of 12.13 MJ/kg consumed more feed than did those receiving another ME level, whereas quails in both ME treatments showed similar feed efficiencies. For weeks 5 to 8, no difference (P>0.05) in weight gain, feed intake and feed efficiency was seen regardless of ME levels, and no interaction existed between ME and CP levels. In Experiment 2, the best weight gain and feed efficiency were achieved when the dietary CP concentration was more than 210 g/kg, and quails treated with 11.51 MJ/kg showed better weight gain and feed efficiency (P<0.05) than did those that received 12.13 MJ/kg. Furthermore, the weight gains and protein intakes on the basis of per MJ from the two experiments were pooled together to estimate the protein intake necessary for the best growth performance by two mathematic models; they were then converted to dietary CP concentrations of 204 (minimum) and 233 g/kg (maximum) when ME was 11.51 MJ/kg. In conclusion, BBQ will achieve good growth performance with dietary CP of more than 204 g/kg on the basis of an ME of 11.51 MJ/kg in weeks 1 to 4.

9.
Animal ; 5(10): 1515-20, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22440341

RESUMO

The aim of this study was to investigate protein requirements for the maintenance and growth of blue-breasted quail (Excalfactoria chinensis) from 7 to 21 days of age. A total of 180 quails, 7 days old, were randomly assigned to 36 cages and for 2 weeks were fed diets with a metabolisable energy concentration of 12.13 MJ/kg and a dietary CP concentration of 125, 150, 175, 200, 225 or 250 g/kg. The average BW per cage and the feed intake per cage were recorded daily. The results showed that quails fed 125 g/kg CP could not maintain their BW and had negative feed efficiency. There were linear and quadratic relationships between CP level and response criteria, including BW, weight gain, feed intake, feed efficiency, final body nitrogen mass and body nitrogen accretion (P<0.05). The dietary CP requirements, as calculated using a one-slope quadratic broken-line model, were 211 and 202 g/kg according to weight gain and feed efficiency, respectively. The regression equations, on the basis of metabolic BW, of daily weight gain on daily protein intake according to the model were Y=0.137-2.128(0.113-X) if X<0.113 and Y=0.137 if X>or=0.113 (R2=0.96, P<0.001), which meant that the protein requirement for maintenance was 0.049 times the metabolic BW and that to gain 1 g weight quails needed to ingest an extra 0.47 g protein after the maintenance requirement was satisfied. The regression equations, on the basis of metabolic BW, of daily body nitrogen accretion on daily protein intake according to the model were Y=5.667-76.700(0.119-X) if X<0.119 and Y=5.667 if X>or=0.119 (R2=0.95, P<0.001), which meant that quails had to receive an amount of protein equal to their metabolic BW multiplied by 0.045 to satisfy the requirement for maintenance and then ingest an extra 13 g protein to accrete 1 g body nitrogen. In conclusion, growth or protein accretion rates should be regulated according to dietary CP for specific experimental purposes via apportioning protein requirements for maintenance v. growth.

10.
Oncogene ; 29(21): 3110-23, 2010 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-20383200

RESUMO

Uncontrolled growth and diffused invasion are major causes of mortality in patients with malignant gliomas. Nodal has been shown to have a central role in the tumorigenic signaling pathways of malignant melanoma. In this study, we show that grade IV human glioma cell lines expressed different levels of Nodal, paralleled to the potential for cell invasiveness. Treatment of glioma cell lines with recombinant Nodal (rNodal) increased matrix metalloproteinase 2 (MMP-2) secretion and cell invasiveness. The ectopic expression of Nodal in GBM glioma cells that expressed Nodal at low level resulted in increased MMP-2 secretion, enhanced cell invasiveness, raised cell proliferation rates in vitro, increased tumor growth in vivo, and was associated with poor survival in a mice xenograft model. In contrast, the knockdown of Nodal expression in U87MG glioma cells with high Nodal expression level had reduced MMP-2 secretion, less cell invasiveness, lower tumor growth in vivo and longer lifespan in mice with U87MG/shNodal cell xenografts. In addition, Nodal knockdown promoted the reversion of malignant glioma cells toward a differentiated astrocytic phenotype. Furthermore, our data support the notion that Nodal may regulate glioma progression through the induction of the leukemia inhibitory factor (LIF) and Cripto-1 through activated Smad.


Assuntos
Glioma/patologia , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana/genética , Animais , Divisão Celular , Linhagem Celular Tumoral , Neoplasias do Sistema Nervoso Central/enzimologia , Neoplasias do Sistema Nervoso Central/genética , Neoplasias do Sistema Nervoso Central/patologia , Progressão da Doença , Fator de Crescimento Epidérmico/biossíntese , Proteínas Ligadas por GPI , Regulação Neoplásica da Expressão Gênica , Técnicas de Inativação de Genes , Glioma/enzimologia , Glioma/genética , Humanos , Peptídeos e Proteínas de Sinalização Intercelular , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/farmacologia , Fator Inibidor de Leucemia/genética , Metaloproteinase 2 da Matriz/genética , Metaloproteinase 2 da Matriz/metabolismo , Glicoproteínas de Membrana/biossíntese , Proteínas de Membrana/metabolismo , Proteínas de Membrana/farmacologia , Camundongos , Invasividade Neoplásica , Proteínas de Neoplasias/biossíntese , Proteínas Recombinantes/uso terapêutico , Proteínas Smad/metabolismo , Inibidor Tecidual de Metaloproteinase-2/metabolismo , Transfecção
11.
Clin Genet ; 71(5): 419-26, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17489847

RESUMO

Thalassemia is one of the most common monogenic disorders in the world. In order to develop a community-based prevention program, we screened 12,900 individuals for alpha- and beta-thalassemia in Baise City, Guangxi, China, with hematological methods and molecular assays. We found that the frequency of carriers in this area for alpha-thalassemia is 15%. Beta-thalassemia carriers comprise 4.8% of the populations. Five mutations account for 98% of alpha-thalassemia [--SEA 46.7%; -alpha/4.2, 23.9%; -alpha/3.7, 21.7%; hemoglobin (Hb) Constant Spring, 6.5%; Hb Quong Sze, 1.1%]. Seven mutations in the beta-globin gene account for 99% of the mutations [codon (CD) 41/42 (-TCTT) (39.4%), CD 17(A-->T) (32%), CD 71/72 (+A) (7.4%), -28 (A-->G) (5.8%), IVS-2-654 (C-->T) (5.8%), CD26 (Hb E) (4%), IVS-1 (G-->A) (3.7%), and CD 43(G-->T) (1.9%)]. Most individuals with alpha-thalassemia major die in the uterus or shortly after birth. Among 106 patients with beta-thalassemia major followed by our clinic, the majority died before 5 years of age. Knowledge surveys about thalassemia were conducted. Our results show a severe lack of knowledge about thalassemia in both medical professionals and in the general populations. This study shows that thalassemia is a very severe public health issue in minority populations in Baise City, China. Identification of the common mutations will allow us to design cost-effective molecular tests. There is an urgent need to educate the general population and the medical community for a successful community-based prevention program.


Assuntos
Grupos Minoritários , Talassemia/epidemiologia , Adolescente , Criança , China , Feminino , Humanos , Masculino , Modelos Genéticos , Mutação , Gravidez , Diagnóstico Pré-Natal , Prevalência , Talassemia/diagnóstico , Talassemia/genética
13.
Cardiovasc Res ; 25(7): 529-36, 1991 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-1913744

RESUMO

STUDY OBJECTIVE: The adenosine hypothesis for the metabolic regulation of coronary blood flow remains controversial, in part because of differences in results obtained between intravascular and endogenously released adenosine. The main objective of this study was to compare the responses of coronary perfusate flow to intravascular and pericardial 2-chloroadenosine and theophylline. The periocardial route was used to simulate physiological conditions. DESIGN: An isolated, perfused guinea pig heart preparation was used. Hearts were submerged in 10 ml Krebs-Ringer bicarbonate solution having the same chemical composition as that used to perfuse the coronary vasculature. The submersion fluid was assumed to simulate myocardial interstitial fluid. Hearts were divided into four experimental groups. The first group (n = 6) was used to check that the submerged hearts functioned normally. The second group (n = 12) was used to compare differences between intravascular and pericardial 2-chloroadenosine. The third group (n = 16) was used to evaluate the two routes of administration of 2-chloroadenosine on transmural distribution of coronary flow. The fourth group (n = 24) was used to test the effects of hypoxia in the absence and presence of pericardial theophylline. EXPERIMENTAL MATERIAL: Hearts were obtained from adult guinea pigs of either sex weighing 300-400 g. MEASUREMENTS AND MAIN RESULTS: All submerged hearts were functionally stable for at least 30 min. Pericardial 2-chloroadenosine was about 1000 times less potent than intravascular 2-chloroadenosine in relaxing the coronary vasculature. Venous concentrations of pericardial 2-chloroadenosine were significantly greater than those of intravascular 2-chloroadenosine, at 0.72(SEM 0.17) v 0.18(0.02) mumol.litre-1. Pericardial 2-chloroadenosine caused more uniform distribution of radiotracer microspheres than intravascular 2-chloroadenosine. Finally, pericardial theophylline significantly attentuated the vasodilator response to hypoxia but not to exogenous adenosine. CONCLUSION: The isolated submerged heart is a viable preparation for investigating the adenosine hypothesis. Our results suggest that intravascular adenosine does not simulate physiological conditions of interstitial adenosine release and action.


Assuntos
2-Cloroadenosina/farmacologia , Circulação Coronária/efeitos dos fármacos , Teofilina/farmacologia , 2-Cloroadenosina/administração & dosagem , Animais , Relação Dose-Resposta a Droga , Feminino , Cobaias , Frequência Cardíaca/efeitos dos fármacos , Técnicas In Vitro , Injeções , Masculino , Oxigênio , Teofilina/administração & dosagem , Vasodilatação/efeitos dos fármacos
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