急性脑梗死患者血清心肌酶学变化的临床意义及相关危险因素分析

目的：探讨急性脑梗死患者血清心肌酶学变化与预后的关系及导致急性脑梗死患者心肌酶学变化的相关危险因素。方法：回顾性分析临床及影像资料齐全且确诊的140例急性脑梗死患者（发病14天内）,根据有无血清心肌酶学升高分为血清心肌酶学升高的急性脑梗死组A组（43例）,血清心肌酶学正常的急性脑梗死组B组（97例）,应用美国国立卫生研究院卒中量表评分（NIHSS）比较两组神经功能缺损情况,并对两组病人血清心肌酶学（包括天冬氨酸氨基转移酶（AST）、肌酸激酶（CK）、肌酸激酶同工酶（CK-MB）、乳酸脱氢酶（LDH）、血糖、血脂、纤维蛋白原和血压等结果进行分析。结果：A组（31%）患者血清心肌酶学均增高,与B组比较均有显著性差异（P〈0.01）;发病后1天A、B两组患者临床神经功能缺损程度评分无显著性差异,发病后4、8、10天A、B两组患者临床神经功能缺损程度评分有显著性差异（P〈0.01）;A组高血压、糖尿病与B组比较有显著性差异（P〈0.05）;而血脂及纤维蛋白原两组比较无显著性差异。结论：急性脑梗死患者血清心肌酶学升高者预后不良;高血压、糖尿病是急性脑梗死患者血清心肌酶学升高的相关危险因素。     

The relationship between trace elements and cardiac markers in acute coronary syndromes

Previous studies have demonstrated increased serum copper and iron levels and decreased selenium and zinc levels in patients with myocardial infarction. Furthermore, the prognostic value of the levels of trace elements in myocardial infarction has been stressed. We examined serum levels of Cu, Fe, Zn and Se, as well as glutathione peroxidase (GPx), a selenoenzyme with antioxidant properties, and C-reactive protein (CRP), a marker of inflammation, in acute coronary syndromes (ACS) regarding their relationship to cardiac troponins and creatine kinase-MB mass (CK-MBm), important prognostic markers. Serum trace elements, GPx activity and CRP were determined in 70 patients with ACS who were admitted within 12 h after the onset. Differences in these parameters were evaluated in three groups of patients divided according to the levels of cardiac markers: group III consisted of patients with high increases in cTnT, cTnI and CK-MBm (> or =0.9 ng/mL, > or =1.0 ng/mL, > or =30 ng/mL, respectively), patients with milder increases in these markers were included in groups II and I consisted of patients with values just above the upper reference limits. Serum Fe levels increased significantly in group II and even more prominently in group III compared to group I (p = 0.04, 0.002, respectively). There was no significant difference between groups II and III. The increase in serum Cu was significant in group III compared to both groups II and I (p = 0.04, 0.001, respectively). There was no significant difference between groups I and II regarding Cu and Zn. The decrease in serum Se and GPx levels was significant only between groups III and I (p = 0.004 for Se and p = 0.0001 for GPx). CRP levels showed a significant increase in group III compared to groups II and I (p = 0.03 and 0.001). CRP showed a significant positive and GPx a significant negative correlation to the cardiac markers cTnT, cTnI and CK-MBm. Cu was positively correlated to all cardiac markers, while the positive correlation between Fe and cardiac markers was significant only for cTnI. Both Zn and Se were negatively correlated to cTnT, and Se was also to cTnI. In conclusion, the increase in serum levels of Cu and Fe and the decrease in serum levels of Zn and Se in patients with higher levels of troponins and CK-MBm imply that trace element levels are related to the degree of myocardial damage and thus may play a role in the pathogenesis of ischemic heart disease. The strong correlations between cardiac markers and both CRP and GPx suggest that these parameters are promising prognostic factors in acute coronary syndromes.     

Use of Na1C14 acetate for biosynthesis of serum and organ lipid components in the early periods of experimental myocardial ischemia]

The use of 1C-14 acetate for biosynthesis of lipids and their fractions (cholesterol, phospholipids, triglycerides and nonesterified fatty acids) in the heart, liver, adrenals, lipoid tissue and blood serum was studied in experimental myocardial infarction on the 5th to the 30th day of the experiment. It was concluded that disturbances of lipid metabolism did not always precede myocardial infarction and acute myocardial ischemia could induce changes in lipid metabolism characteristic of atherosclerosis.     

Assessment of cardiac risk 10 days after uncomplicated myocardial infarction.

A total of 188 patients with uncomplicated acute myocardial infarction (long-term Norris prognostic index 3.2) were rapidly mobilised, underwent a symptom-limited exercise test around the day of discharge from hospital (day 10), and returned to work at a median of six weeks after the acute event. The incidence of cardiac death six months, one year, and three years after infarction was 2.7%, 4.5%, and 7.3% respectively, and the corresponding figures for recurrent heart attacks were 3.4%, 8.2%, and 18.5% respectively. The risk of recurrence of heart attack was predicted by three variables assessed at discharge--namely, a history of classical effort angina (p less than 0.01), radiological heart failure (p less than 0.05), and angina induced by the exercise test (p less than 0.05). The presence of any of these risk factors defined a group of patients with a sevenfold risk of recurrent heart attacks within six months of the initial acute infarct. It is concluded that these risk factors identify a group of patients with a high risk of recurrence early after infarction, in whom vigorous secondary prophylaxis is desirable.     

Sulphinpyrazone in acute myocardial infarction: studies on cardiac rhythm and renal function.

Ninety-eight patients with acute myocardial infarction were randomly allocated to receive sulphinpyrazone 200 mg four times daily or placebo on admission to a coronary care unit. Twenty-four-hour electrocardiogram tape recordings showed no significant reduction in serious arrhythmias in the sulphinpyrazone-treated group. In addition to the expected all in serum urate concentration, patients taking sulphinpyrazone showed a persistent increase in their serum urea and creatinine concentrations when compared with those in the placebo groups (p < 0.05 and p < 0.01 respectively). These differences could not be accounted for by differences in the extent and severity of the infarction between the two groups. These results suggest that sulphinpyrazone has no discernible antiarrhythmic effect in acute myocardial infarction.     

Concentrations of cadmium,zinc, copper,iron, and metallothionein in liver and kidney of nonhuman primates

To evaluate the species specificity of Cd accumulation and the relationship of Cd with other essential metals and metallothionein (MT), the concentrations of Cd, Zn, Cu, and Fe in the liver and kidney and the MT concentrations in the soluble fractions of the liver and kidney were determined in Cd-uncontaminated nonhuman primates (11 species, 26 individuals) kept in a zoo and two wild-caught Japanese macaques. The compositions of metal-binding proteins in the soluble fractions were also investigated by high-performance liquid chromatography (HPLC). The hepatic Cd concentration was 0.03–14.0 μg/g and the renal Cd concentration was 0.35–99.0 μg/g, both varying greatly and being higher in nonhuman primates, which were more closely related to man. The hepatic Zn concentration was 24.0–176 μg/g and the renal Zn concentration was 13.5–138 μg/g, showing 7- to 10-fold differences, and a correlation (r=0.558, p<0.01) was found between renal Zn and renal Cd concentrations. It was proved that in the liver, MT is more closely correlated with Zn (r=0.795, p<0.001) than with Cd (r=0.492, p<0.01) and that in the kidney MT is correlated with both Cd (r=0.784, p<0.001) and Zn (r=0.742, p<0.001). HPLC analysis of metals bound to MT-like protein in chimpanzees, de Brazza’s monkeys, and Bolivian squirrel monkeys showed that more than 90% of Cd in both the liver and kidney, approx 40% of Zn in liver and 28–69% of Zn in kidney were bound to MT-like protein. The higher percentage Zn was bound to high-molecular protein.     

Protein-synthesizing function of the liver of rabbits in experimental myocardial infarct

The content of serum albumin in rabbit blood was found to be lowered within the first day after reproduction of experimental myocardial infarction. The rate and the level of translation of endogenous mRNA were studied in cell-free systems from normal rabbit liver and 6-12-24 h after experimental myocardial infarction. The decrease of the total protein synthesis in the crude cell-free system from the liver of experimental animals was shown to depend on the lack of energy supply rather than on the reduced activity of the protein-synthesizing apparatus. The relative drop of protein synthesis in the cell-free system with saturating concentration of ATP, GTP and creatine phosphate is likely to be connected with a decrease in the proportion of membrane-bound polysomes.     

Trace Element Status of Chronic Renal Patients Undergoing Hemodialysis

The purpose of this study was to examine the status of trace elements (Cu, Zn, and Fe) and minerals (Mg, K, Na, and Cl) and the level of biochemical parameters (urea, creatinine, total protein, albumin, and glucose) in hemodialysis (HD) patients. This study included 30 HD patients (25 men and 5 women) aged 52.12 +/- 3.13 years and 30 healthy subjects (23 men and 7 women) aged 51.64 +/- 2.22 years. This study investigated the status of trace elements and minerals in HD patients. It was found that the total HD patients (before and after dialysis) had statistically lower Zn and albumin in the after-dialysis group K and Cl levels and higher Mg, creatinine, and urea in the before-dialysis group K and in the after-dialysis group glucose levels than those of the controls. It was determined that the results might be helpful in monitoring patients with renal failure in terms of insufficiency or excess of trace elements and minerals. There was positive correlation for Mg-K (r = 0.64; p = 0.001), creatinine-urea (r = 0.59; p = 0.001), K-urea (r = 0.56; p = 0.001), K-creatinine (r = 0.52; p = 0.003), Mg-creatinine (r = 0.47; p = 0.008), Zn-albumin (r = 0.40; p = 0.028), and Zn-creatinine (r = 0.40; p = 0.031) in the before-dialysis session. There was also positive correlation for creatinine-urea (r = 0.56; p = 0.001), K-urea (r = 0.39; p = 0.035), and Mg-creatinine (r = 0.38; p = 0.041) in the after-analysis session. As a result of the analysis of regression between serum levels of albumin and zinc in total HD patients, the use of the level of albumin might be a suitable choice in determining zinc deficiency resulting from the decrease in the level of zinc in parallel to that of albumin. The results also suggest that the relationship between creatinine and K, Mg, and Zn could be ascribed to the loss of renal function.     

老年急性脑梗塞患者血清TNF-a和IL-6水平的变化及其临床意义

目的：观察老年急性脑梗塞（ACI）患者血清TNF-a和IL-6水平的变化并探讨其临床意义。方法：选择老年ACI患者53例,观察以上入选患者入院后第7d、第9d和第11d血清TNF-a和IL-6水平的变化。并与26例健康人对照;同时分析53例老年ACI患者血清TNF—a和IL-6水平与患者脑梗塞面积及神经功能缺损评分的Spearman等级相关性。结果：老年ACI患者血清TNF-a和IL-6水平显著高于健康人（P〈0．01）;随着治疗的进展与病情的稳定及恢复,患者血清TNF-a和IL-6水平随之显著下降（P〈0．05）;同时患者血清TNF-a和IL-6水平与病变的严重程度呈正相关性（P〈0．05）;治疗11d后血清TNF—a和IL-6降低量与病变的严重程度呈正相关性（P〈0．05）。结论：在老年ACI患者治疗过程中,应进行血清TNF-a和IL-6水平的动态监测,可提示病变的发生发展并指导临床治疗。     

Activation of apoalkaline phosphatase by serum albumin with Zn2+ in rat hepatoma cells.

Reuber rat hepatoma cells (R-Y121B) cultured at 0.5% serum accumulated apoalkaline phosphatase in intact cells. When R-Y121B cells were cultured in the presence of bovine serum albumin, alkaline phosphatase activity increased in the cells, and the associated increase in enzyme activity differed amongst bovine serum albumin preparations. The treatment of bovine serum albumin with activated charcoal not only enhanced the effect of serum albumin on alkaline phosphatase activity, but also cancelled the differences due to different preparations of serum albumin. In contrast, no effect from serum albumin was observed in the increase of alkaline phosphatase activity in R-Y121B cell homogenates incubated at 37 degrees C. The activated-charcoal treatment of bovine serum albumin increased the amount of Zn2+ bound to the protein. When R-Y121B cells were cultured with bovine serum albumin, the concentration of Zn2+ in the cytosol fraction slightly increased. However, the effect of serum albumin on Zn2+ concentration in the cytosol fractions was independent of charcoal treatment. It was concluded that serum albumin with Zn2+ induces the activation of apoalkaline phosphatase due to Zn2+ binding.     

Serum zinc and copper in myocardial infarction with particular reference to prognosis

Serum copper and zinc estimations in humans were made to find their diagnostic and prognostic value in cases of myocardial infarction. Following infarction, there was an increase in serum copper levels from the first 24 h up to the 7th day, with gradual decline that did not reach the normal value up to the 14th day. The serum zinc levels declined in the first 24 h until the 4th day and increased to the normal value on the 14th day. It is concluded that, for diagnosis of myocardial infarction, serum zinc levels are more useful during the first week and copper levels in the second week after the onset of infarction.     

老年急性脑梗塞患者血清TNF-α 和IL-6 水平的变化及其临床意义

目的:观察老年急性脑梗塞(ACI)患者血清TNF-α和IL-6水平的变化并探讨其临床意义.方法:选择老年ACI患者53例,观察以上入选患者入院后第7d、第9d和第11d血清TNF-α和IL-6水平的变化,并与26例健康人对照;同时分析53例老年ACI患者血清TNF-α和IL-6水平与患者脑梗塞面积及神经功能缺损评分的Spearman等级相关性.结果:老年ACI患者血清TNF-α和IL-6水平显著高于健康人(P＜0.01);随着治疗的进展与病情的稳定及恢复,患者血清TNF-α和IL-6水平随之显著下降(P＜0.05);同时患者血清TNF-α和IL-6水平与病变的严重程度呈正相关性(P＜0.05);治疗11d后血清TNF-α和IL-6降低量与病变的严重程度呈正相关性(P＜0.05).结论:在老年ACI患者治疗过程中,应进行血清TNF-α和IL-6水平的动态监测,可提示病变的发生发展并指导临床治疗.     

Plasma Selenium, Zinc, Copper and Lipid Levels in Postmenopausal Turkish Women and Their Relation with Osteoporosis

It has been shown that the trace elements and lipids play role in the growth, development and maintenance of bones. We aimed to investigate serum selenium (Se), zinc (Zn), copper (Cu) and lipid (total cholesterol, triglyceride (TG), high density lipoprotein-cholesterol, low-density lipoprotein-cholesterol) levels in postmenopausal women with osteoporosis, osteopenia and in healthy controls, and to determine the relationship between Se, Zn, Cu and lipid parameters and bone mineral density (BMD). The study included 107 postmenopausal women; 35 healthy (group 1), 37 osteopenic (group 2) and 35 osteoporotic (group 3). The women in all three groups were carefully matched for body mass index (BMI). Serum concentrations of Se, Zn and Cu were measured by atomic absorption spectrophotometry. Plasma Se, Cu, Zn and lipid levels were similar in all groups (p?>?0.05). When we combined the women in each of the three groups, and considered them as one group (n?=?107) we found a positive correlation between BMI and lumbar vertebra BMD, femur neck BMD, femur total BMD; a positive correlation between TG and femur neck BMD, femur total BMD; a positive correlation between Zn and lumbar vertebra BMD (total T score) (p??0.05). Although BMI has a positive effect on BMD, trace elements and lipids, except Zn and TG, did not directly and correlatively influence BMD. Further studies are needed to clarify the role and relationship of trace elements and lipid parameters in postmenopausal osteoporosis.     

Elevated serum leptin levels in patients with acute myocardial infarction; correlation with coronary angiographic and echocardiographic findings

ABSTRACT: BACKGROUND: To assess the relationship between serial serum leptin levels in patients with acute myocardial infarction (AMI) who received thrombolysis and the degree of coronary atherosclerosis, coronary reperfusion, echocardiographic findings, and clinical outcome. 51 consecutive patients presenting with AMI were studied. Clinical characteristics including age, sex, body mass index (BMI) and cardiovascular risk factors were recorded. Serial serum leptin levels at the time of admission and subsequently at 0, 6, 12, 24, 36, 60 hours afterwards were obtained. Coronary angiography was performed in 34 patients; the relation between serum leptin levels and evidence of coronary reperfusion as well as the extent of coronary atherosclerosis according to the coronary artery surgery study classification (CASS) were evaluated. Echocardiographic evaluation was performed in all patients. 36 matched patients were enrolled as control group who had serum leptin level 9.4 +/- 6.5 ng/ml. RESULTS: The patients mean age was 50.5 +/- 10.6 years. There were 47 males and 3 females. 37.1% were diabetics, 23.5% were hypertensive, 21.6% were dyslipidemic and 22.7% were obese (BMI [greater than or equal to] 30). Leptin concentrations (ng/ml) increased and peaked at the 4th sample (36 hrs) after admission (mean +/- SD) sample (1) =9.55 +/- 7.4, sample (2) =12.9 +/- 8.4, sample (3) =13.8 +/- 10.4, sample (4) =18.9 +/- 18.1, sample (5) =11.4 +/- 6.5, sample (6) =10.8 +/- 8.9 ng/ml. There was a significant correlation between serum leptin and BMI (r = 0.342; p =0.03). Leptin levels correlated significantly to creatine kinase level on the second day (r = 0.43, p [less than or equal to] 0.01). Significant correlation of mean serum leptin with the ejection fraction (P < 0.05) was found. No difference in timing of peak serum leptin between patients who achieved coronary reperfusion vs. those who did not (p= 0.8). There was a trend for an increase in the mean serum leptin levels with increasing number of diseased vessels. There was no correlation between serum leptin levels and outcome neither during the hospitalization nor at 9 months follow up. CONCLUSION: Serum leptin levels increase after myocardial infarction. Serum leptin level may be a predictor of the left ventricular ejection fraction and the degree of atherosclerosis but not of coronary reperfusion.     

Oxidase activity of ceruloplasmin and concentrations of copper and zinc in serum of cancer patients.

A balance between oxidant carcinogens and endogenous antioxidant defence is of particular relevance to the carcinogenesis. Ceruloplasmin (Cp) carries up to 90% of Cu in plasma and performs ferroxidase, antioxidant and amine oxidase activity. Cu and Zn, as trace elements, have been recognized to play an important role as cofactors of SOD. The study presents the relationship of the Cp oxidase activity and concentrations of Cu and Zn in serum of 62 patients with breast (BCA), lung (LCA), gastrointestinal (GICA) and gynecological (GYNCA) cancer. The Cp oxidase activity was determined in serum with o-dianisidine as a substrate. Cu and Zn concentrations in serum were measured by using atomic absorption spectrometry. The results of the study have shown significant increase in the mean serum Cp oxidase activity and total Cu concentrations in all patient groups compared with the control one. The total mean serum Zn concentration was found to be decreased only in LCA group as compared with the control. The effect of the cancer progress on the Cp oxidase activity and concentrations of Cu and Zn was observed within the group of all cancer patients (ALLCA) and within the GICA group. The only significant difference in Cu concentrations among various stages of the disease was observed in GICA between local and distant one. Significant positive correlation coefficients were caLculated for the Cp activity and Cu concentrations in the control group and all patients groups, also according to the cancer progress. Future research is needed to evaLuate the consequences of the elevation of the serum Cp oxidase activity and concentration of Cp, Cu and Zn for the host antioxidant-oxidant balance.     

The potential use of metallothionein in the clam Ruditapes decussatus as a biomarker of in situ metal exposure

This work aimed to validate the relationship between metallothioneins (MTs) and metals (Cd, Cu and Zn) in field conditions. Specimens of the marine bivalve Ruditapes decussatus (Linné, 1758) from Gargour were transferred in two sites: Gargour and Sidi Mansour, both situated along the south-eastern coast of Tunisia. The bivalves were removed from pairs of cages at day 0 (date of transplantation), day 62 and day 132. Metals (Cd, Cu and Zn) and MTs were determined in the subcellular fractions of the digestive gland. In Gargour, metal and MT levels increased significantly after 62 days of transplantation. However, they showed modest and non-significant variations in Sidi Mansour. Zn was mainly associated with the insoluble fraction, whereas Cd and Cu percentages in the soluble and the insoluble fractions were equivalent. Simple correlation analysis showed a positive and significant relationship between MTs and each metal. If all metals were taken together, multiple correlations showed that MTs were significantly correlated with Cd and Zn, with an important coefficient for Cd, but no significant relationship was observed for Cu. Gel filtration chromatography showed that in the heat stable fraction, the only cytosolic SH rich compounds have an apparent low molecular mass (about 15 kDa), which could correspond to metallothioneins. In the digestive gland of R. decussatus MTs responded to moderate increases of metal contamination, without interference with other factors, and could be a promising biochemical indicator of metal exposure.     

Does stopping smoking delay onset of angina after infarction?

This study was designed to determine the relation between stopping smoking and angina after infarction in survivors of an acute coronary attack. The study population comprised 408 men aged under 60 who survived a first attack of unstable angina or myocardial infarction by 28 days and were smoking cigarettes at the time of their attack. These patients were followed up for an average of nine years. Three hundred and eighty four were alive at the one year follow up examination, when the presence or absence of angina together with habits of smoking were recorded. The prevalence of angina at one year was 19.5% in the 241 who had stopped smoking cigarettes compared with 32.2% in those who had continued (p less than 0.01). Six years later, however, the prevalence of angina after infarction was the same in the two groups. It is concluded that the onset of angina after infarction can be delayed by stopping smoking cigarettes but that this effect is not maintained in the long term.     

血清Trx1、FGL2与急性心肌梗死后心力衰竭患者预后的关系

摘要 目的：探讨血清硫氧还蛋白1（Trx1）、纤维蛋白原样蛋白2（FGL2）与急性心肌梗死后心力衰竭患者预后的关系。方法：选择2019年10月至2020年5月我院收治的158例急性心肌梗死后心力衰竭患者作为观察组,并根据心功能Killip分级分为Ⅱ级组54例、Ⅲ级组57例、Ⅳ级组47例。另选择同期我院收治的102例急性心肌梗死患者作为对照组。入院后采用酶联免疫吸附法（ELISA）检测所有患者血清Trx1、FGL2水平;观察组患者出院后随访2年,并根据是否出现主要不良心血管事件（MACE）将患者分为预后不良组和预后良好组。采用多因素Logistic回归分析影响急性心肌梗死后心力衰竭患者预后的相关因素,采用受试者工作特征（ROC）曲线评估血清Trx1、FGL2对急性心肌梗死后心力衰竭患者预后的预测价值。结果：观察组血清FGL2水平明显高于对照组,血清Trx1水平明显低于对照组（P<0.05）;心功能Killip分级Ⅳ级组患者血清Trx1水平明显低于Ⅱ级组、Ⅲ级组（P<0.05）,血清FGL2水平明显高于Ⅱ级组、Ⅲ级组（P<0.05）。预后不良组患者血清Trx1、LVEF均明显低于预后良好组,而年龄、血清FGL2及血尿酸、血肌酐、N末端B型利钠肽原（NT-proBNP）均明显高于预后良好组（P<0.05）,两组心功能Killip分级比例比较差异有统计学意义（P<0.05）。多因素Logistic回归分析显示,年龄（较高）、心功能Killip分级为Ⅳ级、Trx1下降、FGL2升高均是影响急性心肌梗死后心力衰竭患者预后的危险因素（P<0.05）。ROC曲线结果显示,血清Trx1、FGL2预测急性心肌梗死后心力衰竭患者预后的曲线下面积分别为0.807、0.811,两者联合检测预测急性心肌梗死后心力衰竭患者预后的曲线下面积为0.889。结论：急性心肌梗死后心力衰竭患者血清中Trx1水平降低,FGL2水平升高,且血清Trx1、FGL2水平与患者心功能分级及预后密切相关,可作为评估急性心肌梗死后心力衰竭患者预后的辅助性指标。     

Prolactin is involved in the systemic inflammatory response in myocardial infarction

Prolactin may contribute to an atherogenic phenotype. Furthermore, previous studies have shown that prolactin levels increase in situations of acute stress and inflammation. We therefore aimed to investigate the relationship between prolactin, acute stress and inflammation in patients with myocardial infarction. We performed a case-control study in 40 patients with myocardial infarction and 39 controls, aged 41-84 years. Blood for assessment of prolactin and high sensitive C-reactive protein (hsCRP) was drawn at inclusion, that is, during the acute phase of the event, and 2-3 weeks later. Unexpectedly, prolactin levels at inclusion did not differ between cases and controls (7.0 ng/ml and 6.0 ng/ml, respectively, p=0.28). 2-3 weeks later prolactin levels in cases had not decreased. However, univariate regression analysis indicated that hsCRP is associated with prolactin levels (regression coefficient β 0.11; [95% CI 0.01; 0.21]; p=0.03) in cases during the acute phase of myocardial infarction. Our findings may suggest that prolactin is involved in the systemic inflammatory response, which takes place during myocardial infarction; however, this association may not be strong enough to induce higher prolactin levels in patients with myocardial infarction.