Animal experiments have suggested that the pineal gland produces an anti-gonadotropic hormone. The hamster, for example, undergoes reproductive collapse when kept in short-day periods, an effect which is abolished by pinealectomy. Although there is little direct evidence about the endocrine role of the pineal gland in man, it has been noted that tumours of the pineal gland in young boys are associated with precocious puberty and the human pineal gland has been suggested to produce a substance that holds sexual maturation in check. This observation has been extended by Kitay, who has shown that destructive tumours are associated with precocious puberty whereas hyperactive tumours are associated with delayed puberty. However, no studies have described any change of pineal function with normal puberty. Because two pineal indoles, melatonin and methoxytryptophol, have been shown to be antigonadotropic when administered to animals, we have now measured them in schoolchildren. Our findings show that in young boys there is an abrupt fall in the concentration of melatonin with advancing development suggesting that it may play an important physiological role in the control of human puberty.
SummaryWe investigated the use of measurements of serum concentrations of the cardiac proteins troponins I and T as biochemical markers of myocardial cell damage in 80 patients undergoing vascular or major orthopaedic surgery. Holter electrocardiographic monitoring was carried out before surgery and for 3 days after surgery. Blood samples for troponins I and T and creatine kinase-MB isoenzyme were taken on each of these 4 days. Outcome was assessed at 3 months using a patient questionnaire, general practitioner follow-up and case notes review. Silent postoperative myocardial ischaemia was detected in 21 patients; increases in troponins I and T and creatine kinase-MB occurred in four, six and 17 of these patients, respectively. Eight patients suffered major postoperative complications (cardiac death, myocardial ischaemia, congestive cardiac failure, unstable angina and cerebrovascular accident) and 21 minor complications (poorly controlled hypertension needing increased or new additional treatment, palpitations, increased tiredness or shortness of breath in the absence of known respiratory disease). There were no associations between postoperative ischaemia and cardiac protein concentrations. The relative odds for the associations of major adverse outcome at 3 months after surgery and postoperative ischaemia or increased serum concentrations of the three proteins were 5.39 [95% confidence intervals 1.16±27.67] for postoperative ischaemia; 5.64 [1.07±31.00] for creatine kinase-MB isoenzyme; 17.00 [2.20±116.54] for troponin T and 13.20 [1.12±135.00] for troponin I. We found troponin T to be the only prospective marker for both major and minor cardiovascular complications (relative odds 10.65 [1.26±252.88]).
SummaryWe have previously demonstrated that the peri-operative measurement of increased serum concentrations of the cardiac markers troponins I and T and creatine kinase-MB can be predictors of major cardiovascular outcomes (including cardiac death) at 3 months after surgery. In the present study, we have followed the postoperative course of 157 patients undergoing major vascular surgery or major joint arthroplasty to 1 year using a patient questionnaire, general practitioner follow-up and casenotes review. Increased postoperative marker concentrations were defined as values greater than the upper reference limit. Increases in troponin I and troponin T concentrations, as well as a single elevated creatine kinase-MB and two successively elevated creatine kinase-MB concentrations were measured in 12, 13, 33 and 15 patients respectively. Thirty-nine major adverse cardiac outcomes were recorded (cardiac death, myocardial ischaemia, congestive cardiac failure, unstable angina, cerebrovascular accident and major arrhythmias needing active treatment). There was no association between increases in any of these cardiac markers and cardiac death to 1 year. However, increases in troponin I and both a single elevated creatine kinase-MB and two successively elevated creatine kinase-MB concentrations were associated with an increased incidence of major cardiac outcomes, including cardiac death, to 1 year (odds ratio We have previously described the utility of examining serum cardiac proteins (troponins I and T, and creatine kinase-MB) as predictors of postoperative cardiovascular complications within 3 months of surgery in patients undergoing orthopaedic or vascular surgery [1]. Other authors have reported the use of measuring plasma concentrations of both troponins in the prediction of early major cardiovascular complications (myocardial infarction; unstable angina; left ventricular failure, serious potentially lethal arrhythmias requiring immediate treatment; cardiac death) [2][3][4][5][6]. However, fewer data are available on the utility of the measurement of serum troponins or creatine kinase-MB in the prediction of major cardiac complications (including cardiac death) up to 1 year after surgery.[In this study, we looked for peri-operative changes in three cardiac injury markers (serum creatine kinase-MB and troponins I and T) after anaesthesia and surgery in highrisk patients aged > 45 years, and we have followed the patients for 1 year after surgery in order to identify adverse cardiac complications. We have then determined the associations between increased serum markers and adverse outcome. Methods
Envenoming by a number of species of snake may affect the myocardium or cause electrocardiographic changes; several different mechanisms have been proposed. In a prospective study of snake bite in Papua New Guinea, electrocardiographic changes were observed in 36 of 69 patients (52%) envenomed by the taipan (Oxyuranus scutellatus), 2 of 6 (33%) envenomed by death adders (Acanthophis sp.) and one envenomed by the brown snake (Pseudonaja textilis). Septal T wave inversion and bradycardias, including atrioventricular block, were the commonest abnormalities. There was no haemodynamic deterioration. The cause of these changes is uncertain; only 2 of 24 patients (8.3%) with electrocardiographic changes had markedly elevated plasma concentrations of cardiac troponin T, a sensitive and specific marker of myocardial damage. This suggests that myocardial damage is uncommon following bites by these species. Electrocardiographic abnormalities are most likely to have been caused by a direct toxic effect of a venom component upon cardiac myocyte function; in taipan bites, taicatoxin, a calcium channel blocker, might be responsible.
In a group of 30 black and 30 white healthy workers, matched for age, sex and body weight, serum creatine kinase was significantly higher in black males than in white males (P less than 0.01). Seventeen blacks but only four whites had levels above the accepted upper limit of normal of 195 IU/l. There was no correlation with lean body mass. Elevation of serum creatine kinase need not signify disease in blacks, for whom a separate reference range should be established. Two cases are reported of physically healthy black men subjected to unnecessary investigation on the basis of persistently elevated serum creatine kinase.
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