Calcium ionophore and chemotactic peptide stimulation of peptidoleukotriene synthesis in DMSO-differentiated HL60 cells

The human promyelocytic leukemia cell line HL60 can be differentiated to mature granulocytes upon exposure to DMSO (1.3%, 6 days). The ability of these cells to metabolize arachidonic acid via the 5-lipoxygenase pathway to form 5-HETE, LTB₄, and 5,12-diHETEs, has been previously documented. However, the production of peptidoleukotrienes by DMSO-differentiated HL60 cells has not been previously reported. Arachidonic acid metabolites produced via 5-lipoxygenase were identified by reverse-phase, high-performance liquid chromatography, immunoreactivity specific for peptidoleukotriene, glutamyl transpeptidase transformation, characteristic UV spectra, and GC mass spectra. Leukotriene synthesis in the DMSO-differentiated HL60 cell is maximal at 5 min when stimulated with the calcium ioniphore, A23187 (1M), in the presence of calcium. These cells produce 12.94±1.8 ng/10⁶ cells of LTC₄ and 3.8±0.4 ng/10⁶ cells of LTB₄. LTC₄ and LTB₄ are also synthesized in the undifferentiated cell when stimulated with 1M A23187 and 1 mM Ca²⁺, but in much smaller quantities, i.e., 1.91±0.42 ng/10⁶ cells of LTC₄ and 0.41 ng±0.06/10⁶ cells of LTB₄. The synthetic chemotactic peptide, f-Met-Leu-Phe, also elicits formation of LTC₄ and LTB₄ in a dose-dependent manner in the presence of exogenously added calcium. Maximal stimulation of DMSO-differentiated cells with f-Met-Leu-Phe produces 2.5±0.2 ng of LTC₄ and 1.45±0.2 ng of LTB₄ per 10⁶ cells. The observation that DMSO-differentiated HL60 cells produce LTC₄, as well as other 5-lipoxygenase products, increases the utility of this cell line for unraveling the regulation of leukotriene biosynthesis by granulocytes.     

Effect of a back belt on reaching postures

OBJECTIVE: The present study investigated the effect of a back belt on reach actions. SUBJECTS: Sixteen undergraduate college students (8 male students, 8 female students) ranging in age from 18 to 22 years. Thirteen subjects were included in the final analysis. SETTING: The Department of Psychology at Miami University, Oxford, Ohio METHODS: Using a well-established set of procedures developed in our laboratory for studying reaching, seated adult participants reached for and retrieved an object placed at various distances from them. Reach distances included values both closer than and farther than each subject's maximum seated reach. The reach task had 2 conditions: picking up and retrieving a small block and skewering and retrieving a small bead with a needle. For each task condition, each subject either wore the belt or did not use a belt. RESULTS: Results indicate that when subjects wore the belt while reaching, they tended to have initial transition points (sitting to nonsitting) closer to their bodies than while not wearing the belt. That is, for a distant object, subjects were more likely to raise their bodies out of the chair rather than perform an extreme seated reach, possibly acting to preserve a greater margin of safety. CONCLUSIONS: The back belt consistently modified reaching postures by limiting extreme ranges of motion during a task that required enhanced stability. Furthermore, the methodology and analysis presented in this article when applied to chiropractic will allow us to begin thoughtful investigation of the effects of chiropractic adjustments on postural transitions and margin of safety.     

Experimental coronary arterial occlusion and release: Effects on enzymes,electrocardiograms, myocardial contractility and reactive hyperemia

After less than 1 hour of coronary arterial occlusion, the myocardium suffers irreversible changes as revealed by electron microscopy. Yet, the earliest clinical laboratory indexes of myocardlal infarction—elevated serum enzyme levels and significant Q waves on the electrocardiogram—are not detected until at least 6 hours after coronary occlusion. To study the early period after coronary occlusion in the dog, occlusion of the left anterior descending coronary artery for 1 to 3 hours was followed by release, and coronary sinus and venous enzyme levels, the electrocardiogram and myocardial contractility from the infarcted area, and reactive hyperemia were monitored. Coronary sinus enzyme levels rose within 15 minutes after release of occlusion in half of the experiments with $\text{1}\text{to}\text{1}\text{1}\text{2}$ hours and in all of those with 2 to 3 hours of occlusion, and this rise preceded the rise in venous levels by only 10 to 20 minutes. Significant Q waves appeared 15 to 30 minutes after release of occlusion as the serum enzymes were increasing. Thus, clinically, the delayed appearance of increased serum enzymes and significant electrocardiographic Q waves is probably largely due to a lack of circulation in the infarcted area rather than to prolonged survival time. Also, the venous enzyme level reflects the coronary sinus level minutes later. The presence of viable myocardium in the infarcted area was suggested by elevation of the S-T segment upon reclamping, and by residual myocardial contractility and retained capacity for reactive hyperemia. These findings occurred in some experiments even In the presence of a significant Q wave.     

The postobstructive kidney. Observations on nephron function after the relief of 24 hr of ureteral ligation in the dog

After the relief of 24 hr of complete unilateral ureteral obstruction in the dog, the experimental kidney is characterized by a decrease in filtration rate and an increase in fractional and often absolute excretion of sodium before and after the administration of mannitol. In the hydrated state, the failure to conserve sodium is associated with increases in fractional free water clearance and fractional sodium supply to water-freeing sites signifying that the augmented sodium excretion is derived from a proximal source. In the hydropenic state there is decreased fractional free water reabsorption, and sometimes free water excretion, in the postobstructive kidney. An early plateau in free water reabsorption is associated with an increased fractional excretion of sodium. These findings are attributed to the early development of distal nephron impermeability to water as a result of enhanced distal tubular supply and transport of sodium. There is a decrease in maximal tubular reabsorptive capacity (Tm) of glucose in the post-obstructive kidney which is, however, less marked than the decrease in filtration rate. The fall in filtration rate is to some extent likely due to a dropping out of nephrons from the circulation while the remaining nephrons are hypoperfused. The magnitude of the sodium reabsorptive defect is markedly exaggerated as the concentration of nonreabsorbable solute (mannitol) in the glomerular perfusate is increased. It is concluded that the postobstructive increase in sodium excretion during mannitol administration is in part due to a limit in the capacity to reabsorb sodium against a concentration gradient in the proximal tubule.     

Thyrotropin-releasing Hormone Stimulation of Prolactin Release from Clonal Rat Pituitary Cells: EVIDENCE FOR ACTION INDEPENDENT OF EXTRACELLULAR CALCIUM

Thyrotropin-releasing hormone (TRH) stimulates prolactin release and ⁴⁵Ca²⁺ efflux from GH₃ cells, a clonal strain of rat pituitary cells. Elevation of extracellular K⁺ also induces prolactin release and increases ⁴⁵Ca²⁺ efflux from these cells. In this report, we distinguish between TRH and high K⁺ as secretagogues and show that TRH-induced release of prolactin and ⁴⁵Ca²⁺ is independent of the extracellular Ca²⁺ concentration, but the effect of high K⁺ on prolactin release and ⁴⁵Ca²⁺ efflux is dependent on the concentration of Ca²⁺ in the medium. The increment in ⁴⁵Ca²⁺ efflux induced by 50 mM K⁺ during perifusion was reduced in a concentration-dependent manner by lowering extracellular Ca²⁺ from 1,500 to 0.02 μM (by adding EGTA), whereas 1 μM TRH enhanced ⁴⁵Ca²⁺ efflux similarly over the entire range of extracellular Ca²⁺ concentrations. Although 50 mM K⁺ caused release of 150 ng prolactin from 40 × 10⁶ GH₃ cells exposed to 1,500 μM Ca²⁺ (control), reduction of extracellular Ca²⁺ to 2.8 μM decreased prolactin release caused by high K⁺ to <3% of controls and no prolactin release was detected after exposure to 50 mM K⁺ in medium with 0.02 μM free Ca²⁺. In contrast, TRH caused release of 64 ng of prolactin from 40 × 10⁶ GH₃ cells exposed to medium with 1,500 μM Ca²⁺, and release caused by TRH was still 50 and 35% of control in medium with 2.8 and 0.02 μM Ca²⁺, respectively. Furthermore, TRH transiently increased by 10-fold the fractional efflux of ⁴⁵Ca²⁺ from GH₃ cells in static incubations with 1,500 or 3.5 μM Ca²⁺, hereby confirming that the enhanced ⁴⁵Ca²⁺ efflux caused by TRH in both low and high Ca²⁺ medium was not an artifact of the perifusion system.     

Morphology and distribution of neurons expressing serotonin 5-HT1A receptors in the rat hypothalamus and the surrounding diencephalic and telencephalic areas

Disorders of serotonergic neurotransmission are involved in disturbances of numerous hypothalamic functions including circadian rhythm, mood, neuroendocrine functions, sleep and feeding. Among the serotonin receptors currently recognized, 5-HT_1A receptors have received considerable attention due to their importance in the etiology of mood disorders. While previous studies have shown the presence of 5-HT_1A receptors in several regions of the rat brain, there is no detailed map of the cellular distribution of 5-HT_1A receptors in the rat diencephalon.In order to characterize the distribution and morphology of the neurons containing 5-HT_1A receptors in the diencephalon and the adjacent telencephalic areas, single label immunohistochemistry was utilized. Large, multipolar, 5-HT_1A-immunoreactive (IR) neurons were mainly detected in the magnocellular preoptic nucleus and in the nucleus of diagonal band of Broca, while the supraoptic nucleus contained mainly fusiform neurons. Medium-sized 5-HT_1A-IR neurons with triangular or round-shaped somata were widely distributed in the diencephalon, populating the zona incerta, lateral hypothalamic area, anterior hypothalamic nucleus, substantia innominata, dorsomedial and premamillary nuclei, paraventricular nucleus and bed nucleus of stria terminalis.The present study provides schematic mapping of 5-HT_1A-IR neurons in the rat diencephalon. In addition, the morphology of the detected 5-HT_1A-IR neural elements is also described. Since rat is a widely used laboratory animal in pharmacological models of altered serotoninergic neurotransmission, detailed mapping of 5-HT_1A-IR structures is pivotal for the neurochemical characterization of the neurons containing 5-HT_1A receptors.