Intestinal absorption of calcium in rats given diets containing casein or amino acid mixture: the role of casein phosphopeptides

1. In an attempt to investigate calcium absorption in the rat during the postprandial period, with the least alteration of the physical environment, the undisturbed small intestine was ligated in situ 2.5 or 3.0 h after ingestion of a diet containing 200 g casein/kg or an equivalent amino acid mixture, or 925 g casein/kg. Estimation of Ca absorption was made by comparing the amount of soluble 40Ca or 45Ca in the contents of segments from the rats receiving 45Ca by intubation 30 min after withdrawal of food, ligated after a further 30 min, then killed after 0 or 30 min. 2. Under conditions such that the estimated amount of a marker, polyethylene glycol, in segments ligated in a defined position was little changed in rats killed 30 min apart, the difference in the amount of soluble 40Ca was much higher in the rats fed on the basal diet containing 200 g casein/kg than in other groups. 3. This specific effect on Ca absorption, particularly in the distal portion of the small intestine, could be seen also after 45Ca was directly injected into ligated segments in situ. The amount of 45Ca in the portal blood 15 min after injection of the label was also highest in the rats given the basal diet. 4. The results were in agreement with our previous findings that the formation and accumulation of casein phosphopeptides causes an increase in the amount of soluble Ca in the distal small intestine.

The relationship of transmembrane potential to surface morphology of human atrial muscle and cardiac hemodynamics

A correlative study of transmembrane potential characteristics, surface morphological features of human atrial muscle, and cardiac hemodynamics was carried out in 41 patients, who were divided into 2 groups based on the level of the mean maximum diastolic potentials (MDP). Group A consisted of 19 patients with MDP values ranging from -60.0 to -82.0 mV (mean +/- S.D. = -65.70 +/- 6.63 mV). Group B included 22 patients who had abnormally low MDP (range -36.0- -58.5 mV, mean +/- S.D. = -48.14 +/- 6.72 mV). The differences in electrophysiological data were statistically significant. However, there were no significant differences in the hemodynamic data between the 2 groups. Furthermore, there was poor correlation between the electrophysiological and hemodynamic data in both groups. In group A, scanning and transmission electron microscopy revealed either no changes or only mild alterations in the surface morphology of the atrial myocardium. Various degrees of surface morphological changes, including a focal loss of the endothelium which was always associated with endocardial fibrosis, irregular thickening and lamination of the glycocalyx, disruption of the sarcolemma and complete destruction of the surface membrane structures were more often observed in group B. These results provide valuable evidence that sarcolemmal changes may underlie the electrophysiological alterations in diseased human atria. We suggest that the principal pathogenetic mechanisms leading to the transmembrane potential changes are the altered surface morphology of atrial myocardial cells, resulting from underlying disease processes.

Scanning electron microscopy of human lungs in various forms of heart disease

The surface morphologic features of the lung obtained from 21 patients with various forms of heart disease were investigated by scanning electron microscopy, with particular emphasis on the correlation between the surface pathology and cardiopulmonary hemodynamics. There were almost no pathologic findings on the bronchiolar and alveolar surfaces in patients with normal pulmonary arterial wedge pressure (PAWP). The characteristic changes of the surface morphology of the lung parenchyma in patients with abnormal elevation of PAWP included various degrees of desquamating loss of the bronchiolar epithelium associated with inflammatory cell infiltration and fibrotic changes and focal epithelial disruption of the individual alveoli which often extended to involve the surface of the entire alveoli with perforated rupture of the alveolar septa. The severity of abnormal surface morphologic findings of the lung seemed to correlate to the degree of PAWP. From our results it is concluded that chronic lung congestion plays a major role in the pathogenesis of the surface pathologic changes of the lung in patients with heart disease of various etiologies. Our findings may provide a clearer understanding of the structural and functional relationship of congestive lung and a clinical explanation for pulmonary manifestations in patients with chronic congestive heart failure.

Partial restriction map of Marek's disease virus DNA

A partial restriction map of Marek's disease virus (MDV) DNA was constructed by digestion with endonucleases BamHI, Bg/I and SmaI and by blotting hybridization. The data suggest that there is a terminal heterogeneous sequence at least on one end of the MDV DNA molecule. The data did not reveal four different orientations of the terminal fragments of MDV DNA molecules despite the observation that MDV DNA contains inverted repeat sequences as also present in Herpes simplex virus (HSV) DNA molecules (Cebrian et al., 1981). Terminal deletion of MDV DNA, SalI-H and I, was found in high passage number preparations.

Effects of oral disopyramide phosphate on induction and sustenance of atrioventricular reentrant tachycardia incorporating retrograde accessory pathway conduction

We performed electrophysiologic studies before and after oral administration of disopyramide phosphate, 200 mg every 6 hours, in 20 patients with atrioventricular (AV) reentrant tachycardia using a retrogradely conducting accessory pathway. Disopyramide markedly depressed retrograde accessory pathway conduction by increasing the mean ventricular paced cycle length that produced ventriculoatrial block (less than or equal to 287 +/- 4 to greater than or equal to 392 +/- 22 msec, p less than 0.01); it also depressed antegrade normal pathway AV conduction by increasing the atrial paced cycle length that produced AV block (287 +/- 9 to 328 +/- 7 msec, p less than 0.01). In 14 patients, tachycardia could not be induced or sustained after disopyramide phosphate. In 13 patients, this reflected depression of the retrograde limb with either absence of atrial echoes (nine patients) or induction of nonsustained tachycardia that terminated after the QRS complex (four patients), and in one, it reflected depression of the antegrade limb with induction of a single atrial echo not followed by a QRS response. In six patients, sustained tachycardia could still be induced after disopyramide. Oral disopyramide phosphate is effective in preventing induction of sustained AV reentrant tachycardia in most patients. This effect is achieved by depression of the retrograde limb of the reentrant circuit.

The surface morphology and ultrastructure of renal arterial smooth muscle cells in patients with renovascular hypertension

The surface and internal ultrastructure of renal arterial smooth muscle cells were investigated in 3 patients with renovascular hypertension. The most characteristic features of the surface pathology in hypertrophied smooth muscle cells consisted of various degrees of surface defects, including both extensive loss of surface details and an irregular thickening and disruption of the basement membrane, which was widely separated from the plasma membrane by a clear space. Ultrastructural changes include the appearance of highly lobulated nuclei, multinucleation, disorganization of myofilaments and increased numbers of rough-surfaced sarcoplasmic reticulum and mitochondria, which are usual manifestations of cellular hypertrophy. These results suggest that ionic movement across the cell membranes, particularly of Ca2+, is probably abnormal in hypertrophied smooth muscle cells. This may result in functional disorders of hypertensive arteries.

The pattern of hydatidiform moles in Singapore

Hydatidiform mole is common in Singapore, and the the incidence of malignant trophoblastic neoplastic neoplasia is significantly higher than in Western countries. Within a 10-year period (1968-1977), 538 cases of hydatidiform mole were diagnosed. On retrospective study, 498 (92.6%) were considered to be complete and 40 (7.4%) partial. The ratios of complete to partial moles were similar for the major population groups. In the present study, only complete moles were found to give rise to persistent trophoblastic disease. The lack of such association in partial hydatidiform moles is in keeping with their known low malignant potential. Occasional abnormal post-evacuation hCG curves, however, are being described from other centres, and while the underlying pathology remains largely undocumented, partial moles have to be dealt with on an empirical basis in the light of the hCG follow-up levels.

The surface morphology of the infundibular muscle in patients with tetralogy of fallot

The surface morphology of the infundibular muscles obtained from open heart surgery was investigated in 10 patients with tetralogy of Fallot. Various degrees of abnormal surface morphological changes were observed from the endocardium to the myocardium. In the endocardium striking proliferation of the endothelial cells was usually accompanied by focal loss of the endothelium with fibrotic change. Based on the characteristic alterations of the surface morphology 4 different groups of myocardial cells could be identified: normal myocytes, defective myocytes, sclerotic myocytes, and necrotic myocytes. Because intact surface morphology is responsible for integrated cellular function these pathological findings observed on the surface morphology of the endocardium and myocardium can provide a valuable reference to further understanding of functional disorders of the infundibular muscle in patients with tetralogy of Fallot.

Preoperative and postoperative echocardiographic studies of pulmonic valvular endocarditis

The echocardiographic manifestations of pulmonic valvular endocarditis in a patient with underlying heart disease consisting of a ventricular septal defect and infundibular stenosis are reported. The abnormal shaggy echoes observed on the pulmonic valve were confirmed to be vegetations based on surgical and pathologic findings. This was further proven by the disappearance of the shaggy echoes after surgical excision of the vegetations. We conclude that echocardiograms can detect the presence and disappearance of pulmonic valvular vegetations, which may be of aid in the diagnosis of pulmonic valvular endocarditis.

A fatal congenital myopathy with severe type I fibre atrophy, central nuclei and multicores

An unusual fatal congenital myopathy in a Chinese female infant is described. Muscle biopsy showed type I fibre smallness with central nuclei and focal decrease in oxidative enzyme activities affecting mainly larger type II fibres. Longitudinal sections from glutaldehyde-fixed araldite-embedded material stained with toluidine blue revealed multiple small foci of myofibrillar degeneration (multicores) along the muscle fibres. Electron-microscopic examination confirmed the presence of multicore lesions affecting mainly the larger fibres. In addition, there were definite degenerative changes involving the smaller fibres with central nuclei. The degenerative process started around the pericentronuclear zones with diffuse extension along the whole length of the muscle fibres resulting in severe atrophy. These degenerative changes were similar to those described in pericentronuclear myopathy. It is therefore suggested that the patient might have either had 2 co-existing myopathies viz. multicore disease and pericentronuclear myopathy or a single entity with combinations of features which had not hitherto been described.

Cloning of Epstein-Barr virus (EBV) DNA fragments in pBR32 and Charon3A

Restriction fragments of Epstein-Barr virus (EBV; B95-8) DNA were cloned in the Tc gene of pBR322 (HindIII-F, -G, -I, -J, -K, -L, and -M) and in Charon3A (EcoRI-GI and -G2). Altogether these cloned fragments covered 39% of the entire viral genome. The cloned EcoRI-G2 fragment of EBV (B95-8) DNA was shown to contain, in addition to HindIII-J, two more HindIII-fragments : HindIII-M, which had not been located on the linkage map of the viral genome (Given and Kieff, 1978) and HindIII-N, which had been unrecognized up to now. The utility of this cloning method is discussed in regard to the detailed mapping of a viral genome and large-scale production of the viral DNA.

Linkage map of the fragments of herpesvirus papio DNA

Herpesvirus papio (HVP), an Epstein-Barr-like virus, causes lymphoblastoid disease in baboons. The physical map of HVP DNA was constructed for the fragments produced by cleavage of HVP DNA with restriction endonucleases EcoRI, HindIII, SalI, and PvuI, which produced 12, 12, 10, and 4 fragments, respectively. The total molecular size of HVP DNA was calculated as close to 110 megadaltons. The following methods were used for construction of the map; (i) fragments near the ends of HVP DNA were identified by treating viral DNA with lambda exonuclease before restriction enzyme digestion; (ii) fragments containing nucleotide sequences in common with fragments from the second enzyme digest of HVP DNA were examined by Southern blot hybridization; and (iii) the location of some fragments was determined by isolating individual fragments from agarose gels and redigesting the isolated fragments with a second restriction enzyme. Terminal heterogeneity and internal repeats were found to be unique features of HVP DNA molecule. One to five repeats of 0.8 megadaltons were found at both terminal ends. Although the repeats of both ends shared a certain degree of homology, it was not determined whether they were identical repeats. The internal repeat sequence of HVP DNA was found in the EcoRI-C region, which extended from 8.4 to 23 megadaltons from the left end of the molecule. The average number of the repeats was calculated to be seven, and the molecular size was determined to be 1.8 megadaltons. Similar unique features have been reported in EBV DNA (D. Given and E. Kieff, J. Virol. 28:524-542, 1978).

Comparative studies of herpesvirus papio (baboon herpesvirus) DNA and Epstein-Barr virus DNA

An Epstein-Barr virus (EBV)-like herpesvirus has been isolated from a baboon cell line (594S/F9) by induction with the tumour promoter 12-O-tetradecanoyl-phorbol-13-acetate (TPA). The herpesvirus papio (HVP) DNA was mixed with B95 EBV DNA and was characterized by sedimentation in neutral glycerol gradient as 55S DNA, with a buoyant density of approx. 1.718 g/ml after equilibrium centrifugation in caesium chloride. DNA-DNA reassociation kinetics between B95 EBV and HVP DNA showed that HVP DNA shares about 40% homology with B95 EBV DNA. Blot hybridization of EcoRI fragments of HVP DNA with a 32P-B95 EBV DNA probe showed that most of the EcoRI fragments of HVP DNA were hybridized to B95 EBV DNA, suggesting that the homologous sequences were dispersed throughout the virus DNA.

Isoproterenol-stimulated C-peptide and insulin secretion in diabetic and nonobese normal subjects: decreased hepatic extraction of endogenous insulin in diabetes

After the iv injection of 2 micrograms isoproterenol, peripheral plasma insulin and C-peptide concentrations were measured in 16 nonobese normal subjects and 53 maturity-onset diabetic subjects. Basal insulin (P < 0.01) and C-peptide (P < 0.05) levels were increased in obese diabetic subjects compared to nonobese normal subjects. Isoproterenol-stimulated insulin (P < 0.01) and C-peptide (P < 0.05) increments were increased in obese diabetic subjects compared to nonobese diabetic subjects. Hepatic insulin extraction, measured by comparing the ratios of insulin increment to C-peptide increment after isoproterenol injection, was decreased in both nonobese and obese diabetics compared to normals (P < 0.05). No significant differences in the ratios were found between nonobese and obese diabetics or between patients on diet or sulfonylurea therapy. Age, sex, duration of disease, familial predisposition to diabetes, and diabetic retinopathy did not influence the ratios. Isoproterenol-stimulated C-peptide increments (P < 0.05) and fasting blood glucose levels (P < 0.05) were decreased in diabetics showing decreased hepatic insulin extraction compared to diabetics with normal hepatic insulin extraction. Isoproterenol-stimulated insulin increments in diabetics showing decreased hepatic insulin extraction were higher than in normals (P < 0.05). These studies indicate that hepatic insulin extraction decreases in nonobese and obese diabetic subjects. It might be postulated that the lesser amount of secreted insulin is able to show biological activities more efficiently in diabetics with decreased hepatic insulin extraction.