Human RecQL4 helicase plays multifaceted roles in the genomic stability of normal and cancer cells.

Human RecQ helicases that share homology with E. coli RecQ helicase play critical roles in diverse biological activities such as DNA replication, transcription, recombination and repair. Mutations in three of the five human RecQ helicases (RecQ1, WRN, BLM, RecQL4 and RecQ5) result in autosomal recessive syndromes characterized by accelerated aging symptoms and cancer incidence. Mutational inactivation of Werner (WRN) and Bloom (BLM) genes results in Werner syndrome (WS) and Bloom syndrome (BS) respectively. However, mutations in RecQL4 result in three human disorders: (I) Rothmund-Thomson syndrome (RTS), (II) RAPADILINO and (III) Baller-Gerold syndrome (BGS). Cells from WS, BS and RTS are characterized by a unique chromosomal anomaly indicating that each of the RecQ helicases performs specialized function(s) in a non-redundant manner. Elucidating the biological functions of RecQ helicases will enable us to understand not only the aging process but also to determine the cause for age-associated human diseases. Recent biochemical and molecular studies have given new insights into the multifaceted roles of RecQL4 that range from genomic stability to carcinogenesis and beyond. This review summarizes some of the existing and emerging knowledge on diverse biological functions of RecQL4 and its significance as a potential molecular target for cancer therapy.

Nitric oxide synthase expression in lungs of pulmonary hypertensive patients with heart disease.

Since little is known about the contribution of endothelial nitric oxide synthase (e-NOS) to the mechanism of pulmonary vasospasm and the development of pulmonary vascular occlusive disease, we elucidate how e-NOS is expressed in lung biopsy specimens obtained from operative patients with pulmonary hypertension. Lung biopsy specimens were obtained from 17 patients who underwent open-heart operations for various heart diseases. A piece of normal lung specimen was also obtained from the resected lungs of three lung cancer patients as a control. e-NOS expression was visualized with a monoclonal antibody against e-NOS, and the level of expression was partially quantified. Significantly high levels of e-NOS expression were seen in adult patients, whose preoperative mean pulmonary arterial pressures were greater than 20 mm Hg. In contrast, e-NOS expression in pediatric patients with the same levels of mean pulmonary arterial pressure was the same as that in the controls and in low pulmonary arterial pressure. There was a statistically significant positive correlation between the level of e-NOS expression and Heath--Edwards grading. These data suggest that the e-NOS expression in lung tissue is induced when pulmonary vascular obstructive diseases progress.

Male pseudohermaphroditism due to 3 beta-hydroxysteroid dehydrogenase-isomerase deficiency associated with atrial septal defect.

Male pseudohermaphroditism in a 6 month old boy, due to congenital 3 beta-hydroxysteroid dehydrogenase deficiency, associated with atrial septal defect, is reported. At 2 weeks he required therapy for severe dehydration and projectile vomiting. The parents were first cousins and one female sibling had died suddenly at 2 months. The patient presented with melanoderma, perineal hypospadias with testicles in a bifid scrotum and atrial septal defect (ostium secundum). Complete cytogenetic studies showed a 46,XY karyotype. Serum sodium ranged from 129 to 140 mEq/l and serum potassium from 5.1 to 4.6 mEq/l. Basal plasma hormonal studies showed normal androstenedione (delta 4A), decreased cortisol (F), slightly elevated ACTH, 17-hydroxy-progesterone (17-OH-P) and testosterone (T), and highly increased dehydroepiandrosterone-sulphate (DHEA-S) levels. ACTH stimulation increased and DXM suppression decreased the plasma levels of DHEA-S, 17-OH-P and T but not that of F; hCG stimulation during cortisone therapy did not change the levels of DHEA-S and T. Corticosteroid therapy normalized electrolyte levels and reduced melanoderma and hormonal hypersecretion. Moderately elevated plasma levels of 17-OH-P and T suggest a partial testicular 3 beta-HSD deficiency. The multifactorial inheritance and the relatively high prevalence of atrial septal defect vs the rarity of adrenal enzymatic defect suggest a causal association even if a common genetic factor cannot be excluded.

Serum CK-MB isoenzyme after aortic and mitral valve replacements.

A release of the MB fraction of creatine kinase (CK) enzyme into the serum due to myocardial manipulation and trauma occurs in patients undergoing cardiac surgery. Thus, the appearance of CK-MB activity as such is not sufficient to indicate of perioperative myocardial infarction. The mean (+/- SD) serum CK-MB isoenzyme level was 95 +/- 103 U/l 18 hours after aortic or mitral valve replacement in 76 patients. Thirteen patients undergoing closure of an atrial septal defect served as controls. They had a significantly lower (p less than 0.01) isoenzyme level postoperatively: 45 +/- 39 U/l. Two patients had the ECG changes of definite myocardial infarction after valve replacement and they also showed high CK-MB values, while the other patients with high enzyme level had no ECG signs suggesting acute infarction. CK-MB values correlated with the aortic cross-clamping time (r = 0.39, p less than 0.001) and weakly with the precordial ECG voltage of SV1 + RV5 (r = 0.25, p less than 0.01). While these findings may reflect the sensitivity of a thick myocardial wall to ischaemia during surgery, the postoperative recovery was not related to the serum CK-MB level.

Myocardial injury in infants with congenital heart disease: evaluation by creatine kinase MB isoenzyme analysis.

Total creatine kinase (CK) and the myocardial isoenzyme CK MB activity were prospectively determined in 282 children hospitalized for cardiac catheterization and evaluation for suspected congenital cardiac abnormalities and compared with a hospitalized control group of children without such abnormalities. The percent CK MB and CK MB activity were abnormally elevated in symptomatic children with a large left to right shunt due either to a large ventricular septal defect (n = 22; p less than 0.001) or to complete atrioventricular canal (n = 10; p less than 0.001). Serum CK MB activity and percent CK MB were significantly related to the size of the shunt and the age of presentation with clinical symptoms of congestive heart failure in infants with a ventricular septal defect. CK MB activity was abnormally elevated in infants with symptomatic coarctation of the aorta, either with or without a ventricular septal defect (n = 15; p less than 0.001), and in infants with symptomatic aortic stenosis (n = 4; p less than 0.02). In contrast, CK MB activity was normal in asymptomatic children with coarctation of the aorta (n = 14) or aortic stenosis (n = 8) despite comparable systolic pressure gradients. CK MB activity and percent CK MB were abnormally elevated in those children with the cyanotic congenital cardiac abnormalities of either transposition of the great arteries (n = 32; p less than 0.001) or right ventricular outflow tract obstruction (n = 31; p less than 0.001). These results suggest that children with congenital cardiac abnormalities may have significant myocardial cell injury and release of CK MB that may be detected by the determination of serum CK MB activity. Cell injury may be secondary to arterial desaturation or acute pressure-volume overload, or both, as manifested by clinical symptoms of heart failure and measured hemodynamic variables.

Atrial acetylcholinesterase activity in various heart diseases of man.

Distribution and activity of the acetylcholinesterase enzyme in the human atrial myocardium was studied histochemically in a clinical series of patients subjected to cardiac surgery for (1) uncomplicated atrial septal defect (ASD), (2) ischaemic heart disease (IHD), (3) mitral and/or aortic valvular disease (VHD) necessitating replacement with a prosthetic valve, without major symptoms or signs of myocardial incompensation, or (4) clinically overt congestive heart failure (CHF) due to VHD prior to cardiac surgery. In all specimens, a rich distribution of acetylcholinesterase-positive single axons and small fascicles, constituting a three-dimensional nerve net, was observed within the myocardial tissue. This nerve net was obviously mainly parenchymatous, i.e. unrelated to the blood vessels. Small groups of acetylcholinesterase-positive small nerve cells were observed in some specimens, with loosely woven fascicles of axons emerging from one pole of the ganglia. No differences in the distribution of the acetylcholinesterase activity or in the pattern of the inbuilt intrinsic nervous apparatus were observed in the various groups of patients. All specimens were completely devoid of non-specific cholinesterase activity. It was concluded that (I) the human atrial myocardium is richly supplied with cholinergic intrinsic (post-ganglionic vagal) axons and (II) the acetylcholinesterase activity is not a major determinant of the parasympathetic abnormalities associated with cardiac diseases, especially with myocardial pump failure.

Auricular tyrosine hydroxylase and dopamine-beta-hydroxylase activities and noradrenaline content in ischaemic heart disease.

Assessments were made of the tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DBH) activities as well as the noradrenaline (NA) content of samples excised from right auricular tissue during cardiac surgery on a total of 55 patients with ischaemic heart disease (IHD), valvular heart disease (VHD), uncomplicated atrial septal defect (ASD) or congestive heart failure (CHF). The NA content was significantly higher in the IHD group than in the other three groups. The TH activity was highest in the IHD group although the difference was statistically significant only compared with the ASD and CHF groups. The DBH activity was also highest in the IHD group, but again the difference was statistically significant only compared with the ASD and CHF groups. In the whole material there was a significant positive correlation between the NA content and TH or DBH activity, as well as between TH and DBH activity. In the IHD group there was a significant positive correlation between heart volume and TH activity. The results suggest that at least compared with ASD and CHF, the sympathetic tone is relatively high in IHD, possibly involving an enhanced NA turnover.

Histochemically demonstrable monoamine oxidase activity in the adult human heart in various cardiac diseases.

The present work was undertaken in order to study the role of monoamine oxidase (MAO) enzyme in the genesis of altered cardiac noradrenalin level in the human heart in various underlying pathologic conditions. The histochemical localization and the activity of MAO were studied in the right atrial appendage of man in ischemic heart disease, in valvular heart disease without or with congestive myocardial failure, and in hearts with an uncomplicated atrial septal defect. MAO was found to be localized mainly extraneuronally in the muscle cells, a little activity was detected in the connective tissue spaces, and nerves reacting positively were tentatively identified. There were no significant differences in MAO activity measured photometrically between the various heart disease groups. It seems that MAO activity measured photometrically between the various heart disease groups. It seems that MAO enzyme plays only a small or no role in the genesis of the latered noradrenalin level in the human heart observed in ischemic heart disease or congestive cardiac failure.