Alterations in regional brain catecholamine concentrations after experimental brain injury in the rat

Although activation of brain catecholaminergic systems has been implicated in the cerebrovascular and metabolic changes during subarachnoid hemorrhage, cerebral ischemia, cortical ablation, and cortical freeze lesions, little is known of the response of regional brain catecholamine systems to traumatic brain injury. The present study was designed to characterize the temporal changes in concentrations of norepinephrine (NE), dopamine (DA), and epinephrine (E) in discrete brain regions following experimental fluid-percussion traumatic brain injury in rats. Anesthetized rats were subjected to fluid-percussion brain injury of moderate severity (2.2-2.3 atm) and killed at 1 h, 6 h, 24 h, 1 week, and 2 weeks postinjury (n = 6 per timepoint). Control animals (surgery and anesthesia without injury) were killed at identical timepoints (n = 6 per timepoint). Tissue concentrations of NE, DA, and E were evaluated using HPLC. Following brain injury, an acute decrease was observed in DA concentrations in the injured cortex (p < 0.05) at 1 h postinjury, which persisted up to 2 weeks postinjury. Striatal concentrations of DA were significantly increased (p < 0.05) only at 6 h postinjury. Hypothalamic concentrations of DA and NE increased significantly beginning at 1 h postinjury (p < 0.05 and p < 0.05, respectively) and persisted up to 24 h for DA (p < 0.05) and 1 week (p < 0.05) for NE. These data suggest that acute alterations occur in regional concentrations of brain catecholamines following brain trauma, which may persist for prolonged periods postinjury.

[Reorganization of growth-plate-like tissue by isolated chondrocytes in culture]

Growth-plate cartilage is organized into four cellular zones containing resting, proliferating, maturing, and hypertrophic cells. Rabbit chondrocytes were isolated from growth-plate costal cartilage of 4-week-old New Zealand rabbits, the cells (15 x 10(4)) were suspended in 1 ml of Iscove's modified Dulbecco's medium (IMDM) with 10% fetal bovine serum, 50 micrograms ascorbic acid, and 60 micrograms kanamycin (medium A), then transferred to a 15 ml of plastic centrifuge tube, and centrifuged at 1500 rpm for 5 min. The cell pellet was incubated at 37 degrees C under 5% CO2 in air. The cultures reorganized into growth plate-like tissue which could be seen 7-14 days after cell seeding. This growth-plate, histologically, was organized longitudinally into cellular columns and horizontally into four cellular zones containing resting, proliferating, maturing and hypertrophic cells. The hypertrophic cells in the upper were large in size and round or oval in shape, the proliferating and the mature chondrocytes in the lower were small in size and spherical or elongated in shape. These chondrocytes were surrounded by an extensive matrix. Biochemically, DNA content of cultures began to rise on the 2nd day after cell seeding and reached a plateau after 10 days later. The uronic acid content increased from day 4 and reached the maximum on day 15. In contrast in the early culture, alkaline phosphatase activity was extremely low, it began to rise on day 9 and was the highest on day 20. The sequential increase of DNA, uronic acid and alkaline phosphatase contents was analogous to the in vivo changes of growth-plate chondrocytes.

Classification of fumarate reductases and succinate dehydrogenases based upon their contrasting behaviour in the reduced benzylviologen/fumarate assay

Reduction of fumarate by soluble beef heart succinate dehydrogenase has been shown previously by voltammetry to become increasingly retarded as the potential is lowered below a threshold potential of -80 mV at pH 7.5. The behaviour resembles that of a tunnel diode, an electronic device exhibiting the property of negative resistance. The enzyme thus acts to oppose fumarate reduction under conditions of high thermodynamic driving force. We now provide independent evidence for this phenomenon from spectrophotometric kinetic assays. With reduced benzylviologen as electron donor, we have studied the reduction of fumarate catalysed by various enzymes classified either as succinate dehydrogenases or fumarate reductases. For succinate dehydrogenases, the rate increases as the concentration of reduced dye (driving force) decreases during the reaction. In contrast, authentic fumarate reductases of anaerobic cells (and 'succinate dehydrogenase' from Bacillus subtilis) neither exhibit the electrochemical effect nor deviate from simple kinetic behaviour in the cuvette assay. The 'tunnel-diode' effect may thus represent an evolutionary adaptation to aerobic metabolism.

Carcinomatous encephalitis (miliary metastases): lack of contrast enhancement

Carcinomatous encephalitis is a rare form of brain metastasis in which there is diffuse miliary spread of punctate tumor nodules in a perivascular distribution. In this case, these tiny tumor nodules were seen throughout the cortical and basal gangliar gray matter only on T2-weighted images. Contrast-enhanced CT and T1-weighted MR images did not demonstrate these tumor nodules.

[The variations of PRL, LH, FSH and testosterone in renal disease]

Blood PRL was measured with RIA in 22 males and 19 females with various degrees of renal insufficiency. At the same time, blood LH, FSH, testosterone were studied in all the male patients and 20 sex-age matched healthy subjects. The results showed that the levels of PRL and LH were increased, and the level of testosterone was decreased significantly in male uremic patients. There was a significant negative correlation between PRL and testosterone. All the above parameters were measured again 8-25 days after continuous ambulatory peritoneal dialysis (CAPD) therapy in 5 male uremic patients. The BUN and Cr levels decreased and the clinical manifestations of uremia improved, but the levels of PRL, LH, FSH and testosterone showed no significant changes. The mechanisms of these variations were discussed.

Age structure transition of China's population: regional differentials and implications for development policy

"This article discusses why age structure transition is an important dimension of population to be considered in national development strategy. Further, it compares the process of age structure transition of China's population with the experience of other Asian countries. It shows regional differentials of age structure transition within China and discusses resulting policy issues."

Theoretical analysis of metal-clad single-mode fiber-type polarizers

We present a method, based on the equivalent-current theory of optical waveguide coupling, by which metal-clad optical fiber polarizers can be analyzed. Good agreement between theoretical predictions and previously published experimental results is attained.

Potential organ- or tumor-imaging agents XIX: radioiodinated antiarrhythmic drugs as potential myocardial imaging agents

Iodinated and radioiodinated analogs of propranolol and N,N-dimethylpropranolol were synthesized wherein an iodophenyl moiety replaced the naphthalene ring of the parent drug. These new compounds were evaluated not only for their beta-adrenergic blocking and antiarrhythmic activities but also for their ability to accumulate selectively in myocardial tissue. Like propranol, the iodinated analogs displayed comparable beta-blocking and antiarrhythmic activity, and the order of potency was ortho- > meta- > para-iodophenyl. Quaternization of propranolol and the iodinated analogs eliminated the beta-adrenergic blocking activity but retained the antiarrhythmic property of the secondary amine precursors. Among the quaternary salts, the antiarrhythmic potency was meta- > ortho- > para-iodophenyl. Tissue distribution of the radioiodinated derivatives revealed that only the quaternary derivatives were selectively accumulated in myocardial tissue. These results demonstrate that an iodophenyl ring can substitute for th naphthalene ring in propranolol and its quaternary salt without significant alteration of pharmacological properties. The radioiodinated quaternary derivatives may be useful pharmacological tools in experiments aimed at relating antiarrhythmic activity to myocardial uptake.

Adrenal imaging agents: rationale, synthesis, formulation and, metabolism

In this introductory paper on radionuclide adrenal imaging, the rationale, synthesis, formulation, and metabolism of two clinically well-established and one promisinmg adrenocortical imaging agents are reviewed. Their present clinical utility is reviewed in a separate presentation in this issue. Progress to date in developing a positive imaging agent of the adrenal medulla and tumors of chromaffin tissue will be given brief consideration because there is, as yet, no clinically successful radiolabeled adrenal medulla imaging agent.

A radioiodinated bretylium analog as a potential agent for scanning the adrenal medulla

Studies with radioiodinated bretylium analogs (RIBA) suggested that the p-isomer was capable of concentrating in adrenal medulla. The present studies with 125I-p-RIBA in rats and dogs confirm this property and show its marked and persistent affinity for the adrenal medulla. Analogous studies with 14C-p-IBA indicate that it is the quaternary form of the drug that is retained by the adrenal and that high thyroidal radioactivity following 125I-p-RIBA administration is due to in vivo deiodination of the drug.