Isolation of a novel 38 residue-hypothalamic polypeptide which stimulates adenylate cyclase in pituitary cells

A novel neuropeptide which stimulates adenylate cyclase in rat anterior pituitary cell cultures was isolated from ovine hypothalamic tissues. Its amino acid sequence was revealed as: His-Ser-Asp-Gly-Ile-Phe-Thr-Asp-Ser-Tyr-Ser-Arg-Tyr-Arg-Lys-Gln- Met-Ala- Val-Lys-Lys-Tyr-Leu-Ala-Ala-Val-Leu-Gly-Lys-Arg-Tyr-Lys-Gln-Arg-Val-Lys-Asn-Lys - NH2. The N-terminal sequence shows 68% homology with vasoactive intestinal polypeptide (VIP) but its adenylate cyclase stimulating activity was at least 1000 times greater than that of VIP. It increased release of growth hormone (GH), prolactin (PRL), corticotropin (ACTH) and luteinizing hormone (LH) from superfused rat pituitary cells at as small a dose as 10(-10)M (GH, PRL, ACTH) or 10(-9)M (LH). Whether these hypophysiotropic effects are the primary actions of the peptide or what physiological action in the pituitary is linked with the stimulation of adenylate cyclase by this peptide remains to be determined.

[Analysis and comparison of free amino acids in Rehmannia glutinosa Libosch, and its processed products]

15 kinds of free amino acids were detected in Rehmannia glutinosa and its processed products, it was found that their contents were reduced in processed products.

[Quantitative assessment of pulmonary arterial diastolic and mean pressure using continuous wave Doppler]

Continuous wave Doppler echocardiographic study was performed almost simultaneously with right heart catheterization in 24 patients with a variety of cardiovascular disorders and evidence of pulmonary regurgitation detected by pulsed wave Doppler. Their pulmonary arterial diastolic and mean pressure (PADP and PAMP) measured during catheterization were ranging from 5 to 70.6 (mean 30.26 +/- 18) mmHg and from 6.7 to 91.14 (mean 42.41 +/- 23.23) mmHg, respectively. The right ventricular end-diastolic pressure was within normal limit in all but one. The peak, mean and end-diastolic pressure gradients of pulmonary regurgitation (PPRPG, MPRPG and PRPGed) were calculated using simplified Bernoulli Equation and their correlations with PADP and PAMP were analysed using linear regression method. There were close correlations between all PRPGs and PADP or PAMP (r = 0.85 - 0.94, P less than 0.0001). The best equation for assessing PADP was MPRPG + 6 mmHg (r = 0.94, P less than 0.0001), for PAMP was PPRPG + 8 mmHg (r = 0.92, P less than 0.0001). It is evident that those constants in the equations should be adjusted in individual patient who has coexisting right heart failure.

Allergic contact dermatitis to nickel: bioavailability from consumer products and provocation threshold

Twelve subjects sensitive to nickel underwent patch testing with serial dilutions of nickel sulfate in petrolatum and in water. The provocation threshold (the lowest amount of nickel producing a reaction) varied from 5.2 mg (2.5%) to 0.47 microgram (0.01%) when tested in petrolatum. The provocation threshold was higher with aqueous solutions. The lowest provocation threshold in a statistically significant number of individuals was 1.5 micrograms. Nickel bioavailability from dermatitis-inducing earrings and a necklace was determined by immersing them in plasma, normal saline solution, and synthetic sweat at different pH values over 7 days. Nickel leaching under these conditions exceeded the provocation threshold 1.4- to 93-fold, depending on object and solution. The time course varied with solution. After leaching, surface nickel was measured by the action of dilute nitric acid and total nickel was determined by complete dissolution in aqua regia. Nickel was more bioavailable from earrings than from the necklace, presumably reflecting different metallurgy. Plasma was the most effective solution for removing available nickel from earrings, a possible explanation for the frequent induction of sensitization by ear piercing. Comparison of provocation threshold and leaching results may help determine risks from consumer products.

A model for the release of adsorbed molecules from the surfaces of airborne particulate matter based on liquid-phase desorption from amorphous carbon blacks

The release of molecules adsorbed on the surfaces of amorphous carbon blacks has been studied using liquid-solid chromatography. Adsorbate molecules, adsorbents, and mobile phases were selected on the basis of their relevance as models for the release of toxic agents adsorbed on inhalable environmental particulate matter that originates from the incomplete combustion of organic materials. The presence of surface active groups on the carbon blacks has been shown to adsorb and retain adsorbate molecules selectively, and this selectivity can be reduced by competition for these active groups by the displacing solvent. Release is also governed by the surface coverage of the particles and increases as coverage approaches the monolayer.

An integrated mechanism for systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy based on echocardiographic observations

Although many mechanisms have been proposed to explain systolic anterior motion (SAM) of the mitral valve in hypertrophic cardiomyopathy, the precise mechanism of its onset and cessation remain undefined. The Venturi theory, based on increased flow velocity in a narrowed outflow tract, is widely accepted but fails to explain several important characteristics of SAM. It also neglects the potential role of drag forces generated by interposition of the leaflets into the path of ejection and of factors that would decrease the effectiveness of papillary muscle restraint. In order to obtain further insight into the mechanism of SAM, a detailed geometric study of the left ventricle and mitral apparatus was performed with cross-sectional echocardiography in three equal-sized groups of patients with hypertrophic cardiomyopathy and SAM, patients with hypertrophy and no anterior motion, and normal control subjects. A salient finding was that SAM began prior to ejection in patients with hypertrophic cardiomyopathy, which cannot be explained by the Venturi theory. Further, SAM began and was most prominent in the central portion of the leaflet as opposed to its lateral edges; this finding is not predicted by the Venturi mechanism. In addition to outflow tract narrowing, other structural changes unique to patients with SAM included anterior and inward displacement of the papillary muscles, anterior displacement of the mitral leaflets, and elongation of the mitral leaflets, which were, on the average, 1.5 to 1.7 cm longer than in the other subjects (p less than 0.0001). On the basis of these observations, an integrated mechanism for the initiation and resolution of SAM is proposed that would explain observed features such as onset before ejection and central prominence. This mechanism combines the effects of outflow tract narrowing with those of papillary muscle displacement. In particular, anterior and inward displacement of the papillary muscles can be predicted to alter the effectiveness of chordal support so that the central leaflet portions become relatively slack and are more readily displaced anteriorly. The altered distribution of chordal tension can also be predicted to orient the distal leaflets upward into the outflow tract at the onset of systole, prior to aortic valve opening, so that ventricular ejection will actually drag the interposed leaflets anteriorly. The resolution of SAM can be understood in terms of a reverse Venturi effect created by mitral regurgitation, as well as continued traction of the centrally displaced papillary muscles on the lateral leaflet margins.(ABSTRACT TRUNCATED AT 400 WORDS)

Variable effects of changes in flow rate through the aortic, pulmonary and mitral valves on valve area and flow velocity: impact on quantitative Doppler flow calculations

Doppler echocardiographic methods for measuring volumetric flow through the aortic, pulmonary and mitral valves provide the cardiologist with several potentially interchangeable noninvasive methods for determining cardiac output. In addition, comparison of flow differences through individual valves offers the potential to quantitate shunt flow and regurgitant volumes. To date, however, no study has compared the relative accuracies of each of these flow measurements in a controlled experimental setting. Therefore, in this study, Doppler echocardiography was used to measure aortic, pulmonary and mitral valve flows in seven open chest dogs on right atrial bypass where forward cardiac output was precisely controlled with a roller pump. Correlations with roller pump output were better for Doppler measurements of aortic (r = 0.98, SD = 0.3) and mitral (r = 0.97, SD = 0.3) than for pulmonary (r = 0.93, SD = 0.5) valve flow. Interobserver reproducibility was also better for aortic (r = 0.94) and mitral (r = 0.97) than for pulmonary (r = 0.88) valve flow measurements. All valves showed flow-related increases in cross-sectional area, but the slope of this response was variable: 0.05, 0.16 and 0.21 for the aortic, the pulmonary and the mitral valve, respectively. Increased forward flow through the aortic valve, therefore, was manifested primarily by an increase in velocity, whereas increasing flow through the pulmonary and mitral valves produced more significant area changes with correspondingly smaller increases in the velocity component. Recalculation of Doppler-determined outputs, assuming a fixed valve area for the entire range of flows, resulted in a decreased correlation with roller pump output. Both velocity and valve area should be measured at each flow rate for greatest accuracy in volumetric flow calculations.

A Doppler-two-dimensional echocardiographic method for quantitation of mitral regurgitation

A noninvasive method to accurately quantitate the severity of mitral insufficiency would be of major clinical value. In theory, in the absence of confounding variables, regurgitant mitral flow should represent the difference between forward mitral blood flow and aortic blood flow. Since Doppler-two-dimensional echocardiographic (D2DE) methods for measuring transvalvular mitral and aortic flow have been validated, it should be possible to use mitral and aortic flows derived by this method to calculate regurgitant mitral flow. To assess the validity and accuracy of this combined approach for quantitation of regurgitant flow, we developed an open-chest canine preparation in which we could simulate, vary, and accurately measure degrees of mitral regurgitation. Seven animals were anesthetized and prepared to allow controlled right heart output. Mitral regurgitation was than simulated by placing a flexible conduit incorporating a one-way valve and electromagnetic flowmeter between the left ventricular apex and left atrium. Flow through the tube (effective mitral regurgitation) was varied between 0.2 and 1.8 liters/min and forward cardiac output ranged between 0.5 and 4 liters/min. Transmitral and transaortic flows were calculated by previously reported Doppler methods. Doppler-derived estimates of forward flow through the aortic valve correlated well with the flow measured by flowmeter (r = .92), and regurgitant flow and regurgitant fraction calculated by the D2DE approach also compared well with those measured by flowmeter (r = .84 and .83, respectively). This study demonstrates that mitral regurgitant flow and regurgitant fraction calculated by the D2DE method provide an acceptable measure of both absolute regurgitant flow and the regurgitant fraction in the experimental setting.