Measurement of regional neuronal removal of norepinephrine in man.

We describe here and validate an in vivo technique to measure the regional proportionate removal of norepinephrine (NE) by neuronal uptake (Uptake1) in man. The measurement is based on the steady-state arterial and venous concentrations of tritiated NE and tritiated isoproterenol (ISO) during simultaneous infusion of both. The validity of this technique depends on the removal of circulating NE, but not of ISO, by sympathetic nerve endings and on there being no other factor contributing to the net difference in the plasma disappearance of these catecholamines. To test these hypotheses, we compared the removal of NE in the arm with that of ISO in 14 people and the effects of pretreatment with the specific inhibitor of Uptake1, desipramine, in 8 people. In all the subjects a greater percent of NE than of ISO was removed during passage of blood through the forearm (54 vs. 46%, P less than 0.0001). Pretreatment with desipramine decreased significantly the removal of NE to virtually exactly that of ISO. The difference in NE and ISO clearances by arm tissues was therefore completely accounted for by Uptake1. About 15% of infused NE which is removed in the arm is removed by Uptake1. The ability to measure regional Uptake1 should contribute to better understanding of the relationship between circulating levels of plasma NE and sympathetic neural activity and may allow detection of abnormalities of neuronal norepinephrine removal in clinical disease states.     

MR imaging in thyroid disorders: correlation of signal intensity with Graves disease activity

Thirty-six patients with a variety of thyroid disorders and eight healthy subjects were studied with T1- and T2-weighted magnetic resonance (MR) imaging. Solid benign nodules, malignant tumors, and inflammatory conditions were not distinguishable by thyroidal MR signal intensity, but almost all patients with Graves disease had a moderate to marked diffuse increase in signal intensity at both settings. Quantitative evaluation showed that in these patients, the thyroid-muscle signal intensity contrast ratio was linearly related to both the serum thyroxine (T4) level and the 24-hour radioactive iodine uptake. In three patients treated with iodine 131, this contrast ratio rose or fell in parallel with the serum T4 level and 24-hour radioactive iodine uptake. Either parenchymal changes or increased vascularity in Graves disease, or both, could produce these findings. In patients without Graves disease, signal intensity was not correlated with serum T4 levels. These findings suggest that MR signal intensity may reflect the activity of the stimulatory process in Graves disease and may therefore be a useful measure of thyroid function in this disorder, with both diagnostic and prognostic value.     

Life inside the womb: implications for newborn and infant nurses

The education of nurses working with newborns and infants does not typically include a lengthy discussion on the fetal environment, yet existence in the womb has a significant impact on the long-term outcome. This article is a review of the specific aspects of the fetal environment, including the cervix, uterus, placenta, chorion, amnion, amniotic fluid, and maternal aspects, and the potential meaning of these facets to the newborn and infant.     

Accreditation in the allied health professions

Specialized accreditation in the allied health professions can and will fulfill its basic purpose if its efforts are guided by the principle that evaluation must place its emphasis on the outcome of the educational process, no matter how difficult it may be to assess. This requires the commitment and cooperation of both the accrediting body and the institution and program under review. Accreditation is a vitally important and valuable system in higher education in general, and the allied health professions are no exception. If the system is to be effective, however, every temptation must be resisted by all involved parties to debase it by using it for self-serving purposes. A recognized accrediting agency not only has the right, but indeed the responsibility, to ensure that the graduates of a program under review possess the prerequisite knowledge and skills essential for entrance into a given allied health profession. In cases where that minimal standard is not attained, the program should be required to remove those deficiencies in a timely manner or, if sufficiently serious, have its accreditation withheld or withdrawn. There should be no exceptions to this course of action. Every standard or essential adopted should be defensible on sound educational grounds, and every program should be evaluated according to whether it is in compliance. Accrediting bodies must direct their efforts toward evaluating educational quality. They must respect institutional rights and responsibilities and not even attempt to prescribe what will be taught or by whom, or who will administer a given program. The entire accreditation process must account for institutional diversity and should not discourage experimentation, innovation, or modernization. However, the standards and essentials that are ultimately adopted must be applied uniformly and fairly and not in an arbitrary or capricious manner. Hence, it is imperative that the standards and essentials be stated in such a way that they are clear and understandable. For those programs in which an enhancement or upgrading is deemed necessary for one or more aspects of the educational experience, it would be a genuine service to the institution and its consistuency if the accrediting agency could offer sound advice and suggestions for remedying those factors that may be causing or contributing to the observed deficiencies in the educational outcome. Any responsible institution would welcome such an approach, and the outcome should be an upgrading of the program under review with a concomitant enhancement of the profession involved.(ABSTRACT TRUNCATED AT 400 WORDS)     

Plasma levels of catechols after fasting in intact or adrenal-demedullated rats

We compared arterial plasma levels of catechols after a 24-h fast with levels after 24 h of an ad libitum diet in conscious rats. Epinephrine concentrations were significantly decreased after the fast; levels of norepinephrine, dopa, and dihydroxyphenylglycol were unaffected. Adrenal-demedullated rats had decreased levels of dopa regardless of dietary intake and lower levels of norepinephrine after fasting than during the usual diet. The results indicate that fasting decreases adrenomedullary activity in intact animals, with little or no effect on sympathoneural activity.     

Graded exercise testing early after myocardial revascularization surgery

The response to early graded exercise testing (GXT) was studied in 227 patients at a mean of 15.3 days after myocardial revascularization surgery (MRS). GXT followed a modified Bruce protocol without multiples of resting energy expenditure (MET) restrictions and a target heart rate (HR) of 90% of age-predicted maximal HR. The decision as to precisely when to administer the GXT after surgery was made on an individual case basis by the cardiovascular surgeon and the attending cardiologist. For the data analysis, patients were grouped according to the number of days the GXT was administered after surgery: group 1, 7 to 14 days (n = 164); group 2, 15 to 28 days (n = 46); and group 3, greater than 28 days (n = 17). The use of beta blockers was also determined on an individual case basis by the attending cardiologist rather than on a random basis. Ninety-seven of the 227 patients were on beta blockers. Ventricular ectopic activity (VEA), ST-segment changes (STTC), peak HR, peak systolic blood pressure (SBP), peak rate-pressure product (RPP), and peak METs were assessed during exercise. No major complications occurred during testing. Approximately two thirds (67.4%) of the tests were terminated voluntarily by the patient, and 22.5% were stopped by the attending physician. Only 10.1% of the subjects reached the target HR. Chi-square analysis failed to reveal any association between time of testing after surgery and either STTC or VEA. Analysis of variance failed to reveal any effects of group or beta blocker on peak METs attained during GXT; however, patients not using beta blocker medication attained higher peak HR, SBP, and RPP.(ABSTRACT TRUNCATED AT 250 WORDS)