Thermal denaturation of the Ca2(+)-ATPase of sarcoplasmic reticulum reveals two thermodynamically independent domains

Inactivation of Ca2+ uptake and ATPase activity of the Ca2(+)-ATPase of rabbit sarcoplasmic reticulum was measured and compared to the thermal denaturation of the enzyme as measured by differential scanning calorimetry (DSC) and fluorescence spectroscopy. Two fluorophores were monitored: intrinsic tryptophan (localized in the transmembrane region) and fluorescein isothiocyanate (FITC)-labeled Lys-515 (located in the nucleotide binding domain). Inactivation, defined as loss of activity, and denaturation, defined as conformational unfolding, were irreversible under the conditions used. Activation energies (EA) and frequency factors (A) for inactivation were obtained for the enzyme in 1 mM EGTA and 1 mM Ca2+. These were transformed to a transition temperature for inactivation, Tm (defined as the temperature of half-inactivation when temperature is scanned upward at 1 degree C/min). All denaturation profiles were fit with an irreversible model to obtain EA and Tm for each transition, and the values of these parameters for denaturation were compared to the values for inactivation. In EGTA, denaturation obeys a single-step model (Tm = 49 degrees C), but a two-step model is required to fit the DSC provile of the enzyme in 1 mM Ca2+. The specific locations of tryptophan and the fluorescein label were used to demonstrate that denaturation in Ca2+ occurs through two distinct thermodynamic domains. Domain I (Tm = 50 degrees C) consists of the nucleotide binding region and most likely the phosphorylation and transduction regions [MacLennan, D. H., Brandl, C. J., Korczak, B., & Green, N. M. (1985) Nature 316, 696-700].(ABSTRACT TRUNCATED AT 250 WORDS)

[Influence of subtotal gastrectomy on bile acid concentration, total bacterial counts in the gastric juice, and histologic changes in the gastric mucosa]

The concentrations of bile acids, PH and total bacterial counts in the gastric juice were measured among 44 patients with peptic ulcer before and after subtotal gastrectomy (Billroth II in 14 cases, Billroth I in 10 cases, and PAFPG in 20 cases). Thirty three patients were studied by endoscopy and gastric mucosa biopsy one year after the surgery. The results showed that the fasting gastric bile acids concentrations in both B-II and B-I groups were significantly higher than in PAFPG group, when examined 3 weeks and 1 year postoperatively. The PH and total bacterial counts in gastric juice were increased significantly after B-II and B-I reconstruction compared with PAFPG. The abnormal histology of gastric remnant mucosa was more common in B-II or B-I groups than in PAFPG (P less than 0.05). Our data demonstrated that B-II and B-I gastrectomy caused considerably enterogastric reflux, while PAFPG prevented it effectively by keeping the gastric physiology in a relatively stable status. It is the authors' belief that the results provide objective basis for selecting surgical procedure and evaluating operative effects.

[Preventive effects of fortified pollen on diphenylhydantoin teratogenesis]

This paper reports the preventive effects of fortified pollen and folic acid on diphenylhydantoin (DPH) teratogenesis in pregnant SD rats. The experiment showed that i.p. injection of DPH 75mg/kg per day to pregnant rats on gestational days 7 through 11, and feeding of fortified pollen (pollen 10g/kg per day plus folic acid 20mg/kg per day) or folic acid (20mg/kg per day) on gestational days 0 through 20 may partly prevent the embryotoxicity and fetal toxicity produced by DPH. However, the preventive effects of fortified pollen is better than those of folic acid on the following: decrease of fetal body weight; retarded ossification of metacarpus, proximal phalanx, metatarsus, and supraoccipital bone; sternebrae ossification agenesis; subcutaneous hemorrhage; single eye defect; hydronephrosis and the widening of subarachnoid space. This paper also discusses the possible mechanism of prevention of fortified pollen and folic acid against DPH teratogenesis.

Possible involvement of beta-endorphin in the deteriorating effect of arginine vasopressin on burn shock in rats

The effect of intracerebroventricular injections of arginine vasopressin (AVP) on burn shock in the rat and its possible mechanism were explored in this study. AVP was administered intraventricularly at 30 min intervals (50 ng) in the burned rats. The arterial pressure and electrocardiogram (ECG) were recorded with a multipurpose polygraph before and after burn. Compared with the control, the MAP of the rats in the AVP group was elevated at the initial stage and fell dramatically at the late stage of burn shock with a higher mortality. The ECG of the rats in the AVP group also displayed earlier changes such as elevation of S-T segment, inversion of T wave, and ventricular fibrillation. These findings suggest an unfavorable role of AVP in burn shock. The plasma, hypothalamic, and anterior and posterior pituitary levels of beta-endorphin 3 hr after burn were measured by radioimmunoassay. The increased level of beta-endorphin in the plasma after AVP treatment indicates the possible involvement of beta-endorphin in the deteriorating effect of AVP on burn shock.

Nonconventional joint-transform correlator

A nonconventional joint-transform correlator (NJTC) is discussed. We show that the shift-invariant property of the usual joint-transform arrangement can be preserved. The advantages of the NJTC are the efficient use of the light source, the use of smaller transform lenses, higher correlation peaks, and a higher carrier fringe frequency.

Differentiation of avian adenovirus type-II strains by restriction endonuclease fingerprinting

Three serologically indistinguishable viruses from the avian adenovirus type-II splenomegaly virus of chickens, marble spleen disease virus of pheasants, and hemorrhagic enteritis virus of turkeys, were analyzed by restriction endonuclease fingerprinting. The DNA from these viruses were examined with 6 restriction endonucleases (Bgl II, EcoRI, HindIII, Hha I, Xho I, and BamHI). Markedly different DNA cleavage patterns were found in these virus isolates with all the 5 enzymes, except with BamHI, suggesting genetic differences between isolates of adenovirus type II. Restriction endonuclease analyses were found to provide a method for distinguishing genetically different, and yet serologically similar, strains of avian adenovirus type II.