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Biomedical subjects

D Lang

Publications and source records attributed to D Lang.

At least 163 records · Page 9Linked to original sources
PubMed1989

Endothelium-derived relaxing factor inhibits the formation of inositol trisphosphate by rabbit aorta.

1. The effects of endothelium-derived relaxing factor (EDRF), sodium nitroprusside, 8-bromo-cyclic GMP and atrial natriuretic factor (ANF) on inositol trisphosphate (IP3) levels were studied in isolated rabbit aortic preparations stimulated with noradrenaline. 2. In endothelium-containing preparations, acetylcholine, which stimulated EDRF release, inhibited noradrenaline-stimulated IP3 formation. The EDRF inhibitor haemoglobin reversed this effect. 3. In endothelium-denuded preparations, sodium nitroprusside, 8-bromo-cyclic GMP and ANF each similarly inhibited the rise in IP3 levels stimulated by noradrenaline. 4. These findings show that in rabbit aorta, agents which increase cyclic GMP inhibit the noradrenaline-induced rise in IP3 levels and may provide an explanation for the previously reported observations that cyclic GMP inhibits the noradrenaline-stimulated increase in calcium influx and release of intracellular calcium in vascular smooth muscle.

Acetylcholine↗
PubMed1989

Evidence that specific dopamine-1 receptor activation is involved in dopamine-induced renin release.

Direct effects of dopamine on renin release were examined using static incubations and perifusions of rat renal cortical slices. Dopamine (10(-5)M) significantly stimulated renin release compared with control. To determine which receptors are involved in dopamine-elicited renin release, studies were performed with specific dopamine-1 and dopamine-2 receptor agonists and antagonists, as well as with alpha- and beta-adrenergic antagonists. Fenoldopam, a dopamine-1 receptor agonist, dose dependently stimulated renin secretion both in static incubations and perifusions; whereas quinpirole (10(-7)-10(-5)M), a dopamine-2 receptor agonist, was ineffective. Phentolamine (10(-4)M), an alpha-adrenergic antagonist, did not alter dopamine- or fenoldopam-induced renin release. Similarly, propranolol, a beta-blocker, did not interfere with the renin stimulation of dopamine (10(-5)M) or fenoldopam (10(-6)M) incubations or perifusion experiments; whereas propranolol significantly blocked isoproterenol action. SCH 23390 (10(-5)M), a specific dopamine-1 antagonist, blocked dopamine- and fenoldopam-induced renin. In contrast, pimozide, a dopamine-2 receptor antagonist, was ineffective. These studies indicate that dopamine is a direct renin secretogogue, and its effects seem to be mediated by specific dopamine-1 receptor activation, as neither alpha- nor beta-adrenergic blockers nor dopamine-2 receptor antagonists altered dopamine actions. The results suggest that dopamine produced locally in the kidney may stimulate renin secretion directly by dopamine-1 receptor activation.

Animals↗
PubMed1988

[Secondary myocardial hypertrophy in newborn infants and infants without congenital heart defect].

Secondary hypertrophic cardiomyopathy (HCM) was diagnosed in 55 newborns and infants without heart disease. The 17 newborn infants of diabetic mothers, 23 infants given ACTH treatment for infantile spasms, 9 ventilated premature infants or babies with bronchopulmonary dysplasia and 6 infants with different underlying diseases comprising this group underwent 2-dimensional echocardiography. In almost all cases echocardiographic evidence of HCM resolved after removal of the exogenous or endogenous causative factor. Myocardial effects of several substances are known and their pathophysiological mechanisms are discussed. Since HCM may precede systemic disease or may often be the first pointer to a triggering agent, further diagnostic procedures are always indicated. Hence, the diagnosis of primary HCM should be made by exclusion.

Adrenocorticotropic Hormone↗
PubMed1988

Sensitivity, specificity and predictive value of clinical findings, m-mode echocardiography and continuous-wave Doppler sonography in the diagnosis of symptomatic patent ductus arteriosus in preterm infants.

By means of probability analysis we have compared the diagnostic value of clinical symptoms, m-mode echocardiographic measurements and peripheral arterial flow, assessed by continuous-wave Doppler, in preterm infants with symptomatic patent ductus arteriosus (PDA). Data were obtained in 29 infants with PDA and in 29 controls. The most sensitive clinical finding was a hyperactive precordium. Bounding pulses and a heart murmur were absent in 15% and 20%, respectively of the patients with PDA. M-mode echocardiographic measurements were rather specific for the detection of a PDA but less sensitive. Diastolic backflow in the brachial and femoral arteries was present in the majority of patients with PDA and absent in about 67% of the controls. The values in probability analysis, however, were too low to base a therapy on these findings. The highest sensitivity and specificity (100% each) was found for a disturbed cerebral blood flow with absent or retrograde diastolic perfusion estimated by Doppler sonography.

Blood Flow Velocity↗
PubMed1988

Colorimetric method for assay of serum gamma-glutamyltransferase activity with some L-gamma-glutamyl-carboxyanilides.

A simple method for the assay of serum gamma-glutamyltransferase activity with soluble L-gamma-glutamyl-carboxyanilides is presented. It is based on transformation of aminobenzoic acid liberated by the enzyme into colour complex with 4-dimethyl-aminobenzaldehyde or with 4-dimethylaminocinnamaldehyde in acid medium. Among three carboxyanilides studied the highest enzyme activity was noted with L-gamma-glutamyl-3-carboxyanilide and no activity with L-gamma-glutamyl-2-carboxyanilide. A good correlation was demonstrated for serum gamma-glutamyltransferase activity determined by the new colorimetric method and by the standard one with L-gamma-glutamyl-3-carboxy-4-nitroanilide.

Anilides↗
PubMed1988

In vitro assembly of the outer shell of bacteriophage phi 6 nucleocapsid.

Following dissociation of bacteriophage phi 6 nucleocapsid (NC) by EDTA, a particle composed of protein P8 and corresponding to the outer shell of the NC was assembled in vitro in the presence of Ca2+ and Mg2+. Assembly was obtained from soluble protein constituents above 100 micrograms/ml and was optimal within a temperature range of 22-30 degrees. Assembly did not require the presence of genomic RNA. Crosslinking results of intact NCs and in vitro-assembled outer shells suggested that protein P8 dimers are the structural subunits of the shell. Analysis of the assembly kinetics by electron microscopy suggested that ring-like particles of uniform size, packed in flat hexagonal arrays, are intermediates in outer shell assembly.

Bacteriophages↗
PubMed1988

Endothelium-derived relaxing factor and nitroprusside compared in noradrenaline- and K+-contracted rabbit and rat aortae.

1. The effects of endothelium-derived relaxing factor (EDRF) (as stimulated by acetylcholine in the presence of endothelium), sodium nitroprusside and 8-bromocyclic GMP on mechanical relaxation, calcium (45Ca) influx and cyclic GMP levels were studied in isolated rabbit aortic preparations pre-contracted either by noradrenaline or by high (120 mM) extracellular potassium. 2. The results confirmed a relatively greater effect of these three interventions on mechanical relaxation and on reducing calcium influx in noradrenaline-contracted than in potassium-contracted preparations. 3. The increase in cyclic GMP levels induced by sodium nitroprusside, contrary to previous reports, was no greater in noradrenaline-stimulated preparations than in potassium-stimulated preparations, a finding confirmed in rat aortic preparations, and relaxation was not associated with a significant reduction of calcium influx in the potassium-stimulated preparations. 4. Cyclic GMP-mediated relaxation of potassium contraction thus appears to be due to actions of cyclic GMP other than on calcium influx. 5. These findings suggest that cyclic GMP reduces calcium influx more through receptor-operated channels than through voltage-operated channels. 6. The endothelium-dependent acetylcholine-induced elevation of cyclic GMP was reduced both by noradrenaline and by high extracellular potassium, possibly by altering release or activity of EDRF. 7. The sensitivity of the soluble guanylate cyclase system to stimulation by EDRF and nitrovasodilators appears to be greater in rat than rabbit aortic preparations.

Animals↗
PubMed1988

[The course of myocarditis in childhood].

Seventeen patients, aged from 2 days to 16 1/2 years, all suffering from acute myocarditis, were observed between 1975 and 1987. At the onset of the acute infection all patients had a severe disfunction of the left ventricle. Two patients died after hospital admission. Death occurred after one day and after five days, respectively. Postmortem examination showed inflammatory reaction within the myocardium with cellular infiltrates in both cases, and a variable degree of myocardial necrosis in one. The remaining 15 patients had follow-up check-ups between 2 months and 8.25 years later. Electrocardiographic abnormalities disappeared within 3 month in all patients, and the reduced fractional shortening of the left ventricle became normal in 80% of the patients after 5.5 months. At the last follow-ups one patient showed dilated cardiomyopathy. The other patients showed complete recovery regarding their functional capacity and regarding other clinical findings even though 50% still had some minor abnormalities in the echocardiogram and on the chest x-ray. Based on the findings of this follow-up investigation, the prognosis of acute myocarditis in childhood seems as being favourable, although some residual myocardial damage may occur. In most cases this residual myocardial damage is clinically and functionally insignificant. However, in some rare cases, significant chronic myocardial damage will be found.

Acute Disease↗
PubMed1988

[Hypoplastic left heart with transposition of the great arteries].

Hypoplastic left heart syndrome (HLHS) is a rare congenital cardiovascular malformation with a fatal outcome, despite increasing cardiosurgical therapeutic options. Experiences in three cases are reported which were diagnosed as HLHS in the uncommon combination with transposition of the great arteries (TGA). Pathophysiology, clinical features and diagnostic approaches of the "classic" HLHS and the version with TGA are compared. In contrast to the poor clinical outcome, due to impaired systemic and coronary perfusion in patients with classic HLHS, HLHS with TGA leads to reduced pulmonary perfusion, which can be relieved by aortopulmonary shunt operation. After successful operation, two patients showed normal development during the follow-up period of 18 months and 2 years resp. Because of different therapeutic and prognostic consequences in the two lesions, the necessity to determine topographic relations of great arteries in HLHS is stressed.

Angiocardiography↗
PubMed1987

Length, mass, and denaturation of double-stranded RNA molecules compared with DNA.

The contour lengths of linear, double-stranded (ds) RNAs from mycovirus PcV and Pseudomonas bacteriophage phi 6 have been measured with samples prepared for the electron microscope from 0.05 to 0.5 M NH4Cl solutions. A linear dependence of contour length on the logarithm of ionic strength was found and compared with that of dsDNA (pBR322, linearized and open-circular forms). Conditions for molecular weight determinations of any natural dsRNA by electron microscopy have been established, and the method has been calibrated with phi 6 dsRNA of known nucleotide sequence. The results imply that dsRNA in 0.20 M NH4Cl solution has a rise per basepair of 0.271 nm, which is shorter than that in the A-conformation (4%) and in the A'-conformation (10%). The thermal behavior of dsRNA in terms of melting temperature and exhibition of fine structure of melting curves was found to be generally similar to that of dsDNA, as expected from the literature. Folding of dsRNA in ethanolic solution was similar to that of dsDNA. However, in contrast to dsDNA, coiled coils could not be induced by ethanol, which is consistent with dsRNA being stiffer than dsDNA. Concerning dsDNA, the results show that a contraction in rise per basepair by 0.1 nm is coupled with an increase in the winding angle between basepairs by 0.47 degrees, as qualitatively predicted by polyelectrolyte theory.

Bacteriophages↗
PubMed1987

The dodecahedral framework of the bacteriophage phi 6 nucleocapsid is composed of protein P1.

The outer layer of the bacteriophage phi 6 nucleocapsid (NC) was removed by EDTA and reassociated with the core in the presence of Ca2+ or Mg2+. The core was relatively inaccessible to trypsin digestion, was composed of protein P1, and was in the dodecahedral framework reported previously. (H.T. Steely, Jr., and D. Lang, J. Virol. 51:479-483, 1984; Y. Yang and D. Lang, J. Virol. 51:484-488, 1984). The double-stranded RNA genome became RNase sensitive after EDTA treatment of the nucleocapsid.

Bacteriophages↗
PubMed1987

MRI measurement of syrinx size before and after operation.

When patients with syringomyelia fail to improve after operation, factors such as incomplete cyst decompression or type of operation are often implicated. MRI has been used to confirm adequate syrinx decompression post-operatively and to compare the degree of collapse with the type of operation. Foramen magnum decompression was at least as effective in reducing cyst size as syringo-subarachnoid shunting. MRI may also provide a better classification of syringomyelia.

Foramen Magnum↗
PubMed1986

[Long-term observation of ventricular extrasystole in children with normal hearts].

UNLABELLED: Between 1971 and 1980 uniform ventricular extrasystoles, classified as benign, were noticed in 47 children with normal hearts. After a mean observation period of 4.4 years 27 of these children, mean age 10.5 years, could be reexamined. This involved physical examination followed by resting and exercise ECG, 24-hour continuous ECG and echocardiography. Of the 27 children, 18 still had extrasystoles having the same morphological characteristics and identical behaviour under exercise as those seen on first examination. Nine children were free of extrasystoles in all ECG examinations. In none of the 27 children were there any complaints between the first and the second examination or signs of degeneration of the extrasystoles into threatening dysrhythmias. CONCLUSION: Uniform extrasystoles disappearing or decreasing on exercise in otherwise healthy children require no treatment even when occurring frequently and persisting over years.

Adolescent↗