The renin-angiotensin-aldosterone system in normal elderly subjects

In order to observe alterations of the Renin-Angiotensin-Aldosterone (RAA) system in elderly individuals, 40 healthy Venezuelan mestizos (8 men, 32 women) over 60 years of age were examined. These subjects had a normal sodium and potassium diet and were living under normal conditions. Plasma Renin Activity (PRA), urinary and serum aldosterone levels were determined by radioimmunoassay after two hours of ambulation. Values obtained were compared to those of a similar control group under age 60. The study of the RAA system demonstrated a correlation between PRA, serum and urinary aldosterone, and the daily excretion of sodium, even though less significant than in younger subjects. A continuous, gradual descent in these parameters was observed to be related to the advancement of age until approximately age 60, at which time the PRA demonstrated a sudden drop which was not accompanied by a decrease in the level of aldosterone. The most significant changes occur around the sixth decade of life when these hormone levels drop suddenly and the relationship between PRA, urinary and serum aldosterone changes.

Nitrogen bridgehead compounds. 18. New antiallergic 4H-pyrido[1,2-a]pyrimidin-4-ones. 1

A new type of antiallergic agent, 9-hydrazono-6,7,8,9-tetrahydro-4H-pyrido[1,2-a]pyrimidin-4-ones, was synthesized and evaluated for inhibitory effects in the rat reagenic passive cutaneous anaphylaxis (PCA) screen. Several racemic 6-methyl derivatives were found to be more potent than disodium chromoglycate intravenously and some were also active orally. Structure-activity relationships are discussed. High stereospecificity was observed in the 6-methyl series between the enantiomers with 6S and 6R absolute configuration, the former being more active. Compound 17, (+)-6(S)-methyl-9-(phenylhydrazono)-4-oxo-4H-pyrido[1,2-a]pyrimidine-3-carboxylic acid [Chinoin-1045; UCB L140], has an ED50 value of 1.0 mumol/kg po and is now under clinical investigation.

Structural basis for the deoxyribonucleic acid affinity of bleomycins

The role of the bithiazole moiety of bleomycin in the interaction of the antibiotic with DNA has been studied by the use of synthetic bithiazole derivatives. The DNA affinity of individual C-terminal (bithiazole) analogues of bleomycin was measured in terms of the ability of these species to block the binding of bleomycin to DNA, as judged by diminution of the DNA degradation that attends bleomycin binding. DNA degradation was monitored both by release of [3H]thymine from radiolabeled PM-2 DNA and by alteration of bleomycin-treated DNA oligomers of defined sequence derived from Escherichia coli plasmid pLJ3. It was found that the affinity of the bithiazole derivatives for DNA depended on the presence of the bithiazole moiety itself but more importantly on the number and spacing of positively charged groups; 2'-(2-aminoethyl)-2,4'-bithiazole-4-[3-[(4-aminobutyl) amino]propyl]carboxamide (14), having three positively charged groups at neutral pH, was a reasonably effective inhibitor of DNA degradation by bleomycin. Consistent with the importance of the spacing of the positively charged groups, tetrapeptide S (12) was found to be significantly less inhibitory toward DNA degradation by bleomycin than tripeptide S, in spite of their equal number of positively charged groups and the greater structural similarity of the former to bleomycin A2. Bleomycin is known to cleave DNA perferentially at certain sequences. It was shown that the inhibitors employed in this study diminished DNA cleavage proportionately at each cleavage site; no alteration was observed in the specificity of cleavage. A number of the bithiazole analogues employed as inhibitors of bleomycin-mediated DNA degradation were also utilized in fluorescence quenching experiments with calf thymus DNA. Consistent with the belief that these species inhibit bleomycin degradation by competitive binding to the DNA substrate, the best inhibitors exhibited the greatest fluorescence quenching upon admixture of DNA.

The cardiovascular effects of acute hypoxemia as a diagnostic aid

Acute hypoxemia produces opposite effects on the pulmonary and systemic vascular resistance. To assess the influence of acute hypoxemia on cardiac murmurs, 36 patients with a single valvular or congenital heart lesion were studied. As expected from these hemodynamic effects, right-sided regurgitant type murmurs increased in intensity during acute hypoxemia, while stenotic type murmurs were reduced. In contrast, left-sided murmurs remained constant or changed in opposite direction to their equivalent type from the right side. Additionally, acute hypoxemia produced a marked reduction of the murmurs due to left-to-right shunts and allowed an adequate differentiation of the murmurs due to ventricular septal defect from those due to mitral incompetence.

Perceptions of intergenerational relations and psychological well-being among elderly Mexican Americans: a causal model

A simple path analysis model is applied to data on ninety-eight older Mexican Americans residing in southwest San Antonio. Measures of perceived intergenerational solidarity and activity are treated as intervening variables between health and socioeconomic status on the one hand and life satisfaction on the other. The addition of intergenerational solidarity to the other three independent variables found to be consistent predictors of life satisfaction in previous research contributes significantly to the explanation of life satisfaction. The variable fails, however, to play a significant intervening role except between health and life satisfaction.

The treatment of adult obesity through direct manipulation of specific eating behaviors

The present study investigated the effects of three different conditions on weight loss in adult obese subjects. The three conditions were: (1) Monitoring-Contract (MC) in which subjects were reinforced by the return of a valued possession for changes in eating habits; (2) Monitoring (M); and Attention-Placebo (AP). Subjects in the MC group lost significantly more absolute weight and a significantly greater percentage of weight at the end of treatment than did the subjects in the M and AP groups. These changes were still manifested at a 2 month and a 6 month follow-up. The long-term advantages of a weight reduction program which focuses on a gradual and systematic weight loss through changes in eating habits are discussed.

Temperature-sensitive forms of large and small invertase in a mutant derived from a SUC1 strain of Saccharomyces cerevisiae

Mutagenesis of the sucrose-fermenting (SUC1) Saccharomyces cerevisiae strain 4059-358D yielded an invertase-negative mutant (D10). Subsequent mutagenic treatment of D10 gave a sucrose-fermenting revertant (D10-ER1) that contained the same amount of large (mannoprotein) invertase as strain 4059-358D but only trace amounts of the smaller intracellular nonglycosylated enzyme. Limited genetic evidence indicated that the mutations in D10 and D10-ER1 are allelic to the SUC1 gene. The large invertases from D10-ER1 and 4059-358D were purified and compared. The two enzymes have similar specific activity and Km for sucrose, cross-react immunologically, and show the same subunit molecular weight after removal of the carbohydrate with endo-beta-N-acetylglucosaminidae H. They differ in that the large enzyme from the revertant is rapidly inactivated at 55 degrees C, whereas that from the parent is relatively stable at 65 degrees C. The small invertase in extracts of D10-ER1 is also heat sensitive as compared to the small enzyme from the original parent strain. The low level of small invertase in mutant D10-ER1 may reflect increased intracellular degradation of this heat-labile form. In several crosses of D10-ER1 with strains carrying the SUC1 or SUC3 genes, the temperature sensitivity of the large and small invertases and the low cellular level of small invertase appeared to cosegregate. These findings are evidence that SUC1 is a structural gene for invertase and that both large and small forms are encoded by a single gene. A detailed genetic analysis is presented in a companion paper.

SUC1 gene of Saccharomyces: a structural gene for the large (glycoprotein) and small (carbohydrate-free) forms of invertase

Saccharomyces cerevisiae revertant strain D10-ER1 has been shown to contain thermosensitive forms of the large (glycoprotein) and small (carbohydrate-free) invertases and a very low level of the small enzyme, along with a wild-type level of the large form (T. Mizunaga et al., Mol. Cell. Biol. 1:460-468, 1981). These characteristics cosegregated in crosses of the revertant strain with wild-type sucrose-fermenting (SUC1) or nonfermenting (suc0) strains. In addition, there is tight linkage between sucrose and maltose fermentation in revertant D10-ER1 (characteristic of the SUC1 and MAL1 genes). From this we infer that a single reversion event is responsible for the several changes observed in D10-ER1, and that this mutation maps within or very close to the SUC1 gene present in the ancestor strain 4059-358D. The revertant SUC1 allele in D10-ER1 (termed SUC1-R1) was expressed independently of the wild-type SUC1 gene when both were present in diploid cells. Diploids carrying only the wild-type or the mutant genes synthesized invertases with the characteristics of the parental Suc+ haploids. The possibility that a modifier gene was responsible for the alterations in the invertases of revertant D10-ER1 was ruled out by appropriate crosses. We conclude that SUC1 is a structural gene that codes for both the large and the small forms of invertase and suggest that SUC2 through SUC5 are structural genes as well.

Metabolic relationship between invertase and acid phosphatase isoenzymes in Saccharomyces cerevisiae

Repressed cells of Saccharomyces cerevisiae, subjected to inhibition of both RNA and protein synthesis, showed a pattern of membrane-bound and cytosol acid phosphatase to the external enzyme which seemed to be linked through a precursor-product relationship. Gel exclusion chromatography did not indicate clear differences between the isoenzymes. Moreover, centrifugation experiments in CsCl and precipitation with concanavalin A suggested that there were no acid phosphatase molecules devoid of carbohydrate. Membrane-bound invertase displayed a molecular weight and a carbohydrate to protein ratio smaller than those of the exocellular enzyme. The values of molecular weight and buoyant density of the membrane-bound enzyme were closer to those found for the cytosol invertase. The stability of the level of the soluble invertase detected in the cytoplasm under derepression conditions, or after RNA or protein synthesis inhibition was found to be only apparent and represented the result of an equilibrium between synthesis and degradation.

Rupture of the inferior vena cava during open-heart surgery. Aetiology and surgical management

Bleeding during open-heart surgery is a not unusual complication. Rupture of the inferior vena cava during dissection of the heart from adhesions from a previous operation for mitral disease or congenital palliative surgery is a serious and sometimes fatal complication. Its treatment is a challenge even to the most experienced heart surgeon. In two of our three patients, vena cava rupture occurred during open-heart surgery for correction of mitral and aortic valvular disease. In one patient, congenital infundibular stricture of the right ventricle, associated with tricuspid valve insufficiency, was present. In this report, some relevant data were presented from each case and the aetiology of the rupture is discussed.

Successful replacement of the aortic valve, mitral valve and ascending aorta with re-implantation of the coronary arteries

A 63-year-old man was operated upon with replacement of the aortic valve, mitral valve and ascending aorta with re-implantation of the coronary arteries. A composite graft with a 27 mm Björk-Shiley tilting disc prosthesis was inserted with 3 continuous Prolene sutures in the aortic position. The coronary arteries were thereafter re-implanted in holes made in the graft. A 31 mm Björk-Shiley valve was sutured in the mitral position with about 20 isolated mattress sutures of Ti-Cron. Selective myocardial hypothermia was instituted with Ringer's solution of 4 degrees C. The total perfusion time was 185 min compared with 240 and 275 min in two previously reported, similar cases. We consider that the use of cardioplegia, a composite graft and continuous sutures makes it possible to reduce the operation time in these complex cases. Our patient is in good condition 9 months postoperatively.

Human tumor-lymphocyte interaction in vitro. III. T lymphocytes in autologous tumor stimulation (ATS)

The T-cell nature of the responding cells in autologous tumor stimulation (ATS) was proven by (1) E-rosette formation of lymphocytes attached to tumor cells during the early period of co-cultivation; (2) blast-transformed E-rosetting cells detectable at the end of the test period (day 6) and (3) the reactivity of T-enriched lymphocyte subset and unresponsiveness of T-depleted fractions. Preparation of tumor suspensions devoid of lymphocytes made it possible to carry out cross-tests between patients. Blastogenesis with allogeneic tumors was rare. The restricted autologous nature of the reaction is a strong indication for genuine tumor-relatedness.

Regulation of acid phosphatase synthesis in Saccharomyces cerevisiae

In Saccharomyces cerevisiae-136ts (Hutchison, H.T., Hartwell, L.H. and McLaughlin, C.S. (1969) J. Bacteriol. 99, 807--814) derepressed acid phosphatase was almost exclusively located outside the permeability barrier. Only a minor part of the activity was associated with the protoplasts; about half of it (48%) in the soluble fraction, the rest bound to the internal (45%) and plasma (7%) membranes. The activity found in the membranes of derepressed cells decreased by 30--40% after addition of inorganic phosphate or cycloheximide suggesting that this activity is the precursor of the external enzyme. The alkaline phosphatase activity level could not be modified by changes in the concentration of inorganic phosphate. Acid phosphatase was not synthesized if the cells were transferred to a low phosphate medium at the moment of incubation at 37 degrees C or in the presence of cycloheximide at 23 degrees C. The data suggested that enzyme formation is the result of the transcription and translation of a specific gene(s) and not the activation of a proenzyme. Inorganic phosphate did not inhibit the translation of mRNA though it may act at the level of the transcription.

Two-stage replacement of tricuspid valve in active endocarditis

One month after a 21-year-old female drug addict with tricuspid staphylococcal endocarditis seemed to have been cured by antibiotic therapy she relapsed. Further antibiotic treatment for one month failed to control the infection. Tricuspidectomy was when performed and the infection was eliminated. A valve prosthesis was inserted 3 months later. She recovered and is now fully restored to health. We recommend this two-stage surgical technique in similar cases.

Percutaneous fixation of supracondylar fractures of the humerus in children

Of 1,118 supracondylar fractures of the humerus in children treated over a six-year period, 189 are described with a follow-up of more than two years. These patients were treated with closed reduction and percutaneous fixation of the fragments with two wires. Eighty-five per cent of the final results were satisfactory.

Left ventricular rupture as a complication of mitral valve replacement

We are not the first to attempt repair of left ventricular rupture complicating mitral valve replacement, as 18 analogous cases have been reported earlier in the literature. Our series comprises 8 patients, 5 of who, survived. A review of these 26 cases provided several facts of interest to surgeons dealing with this complication. The rupture occurred either as a laceration in the posterior atrioventricular groove (type I, 16 of 26 patients) or as a perforation of the midportion of the left ventricle (type II, 10 of 26 patients). Intraoperative rupture (17 of 26 patients) was usually detected on termination of bypass, whereas delayed rupture (9 of 26 patients) occurred after chest closure or in the recovery room. The morality rate was about 50 per cent for the intraoperative type, and no patient survived a delayed rupture. The prognosis appeared to be most in intraoperative type II lesions. The main factors affecting the prognosis were (1) instant reinstitution of extracorporeal circulations and (2) avoidance of the circumflex coronary artery during repair of type I lesions located close to the anterolateral mitral commissure. Attempts to suture a ventricular rupture on the pressure-loaded, beating heart were always unsuccessful and frequently extended the laceration. Patients with the delayed type of rupture died of hemorrhage before they could again be placed on bypass. It may be preferable to reopen the lefr atrium in order to repair a type I laceration. In type II perforations, direct repair with buttressed sutures should be attempted from the exterior of the heart. The angulated metal cannula for drainage of the left ventricle was identified as a possible, but not previously reported, cause of myocardial perforation. It is hoped that the use of a soft cannula or a metal cannula with an angle of 60 degrees instead of 90 degrees will reduce the incidence of this complication.

Surgical implications of right aortic arch with isolation of left subclavian artery

Few cases have been reported of the combination of right aortic arch with isolation of the left subclavian artery in childhood because of the absence of symptoms from this pairing of defects and the difficulty of its recognition by routine examination. All the reports have been associated with congenital heart disease. We report 4 cases. In one of them, the diagnosis was made during an attempt to create a left Blalock-Taussig anastomosis and the technique was modified. The diagnosis can be made before operation with an aortogram. This procedure should be carried out to show the aortic arch branches in cases where palliative surgery is contemplated.

Modification by calcium dobesilate of histamine effects on capillary ultrastructure

The ultrastructure of blood capillaries and venules are studied in rat skin. After i.v. injection of histamine the luminal surface of the endothelial cells show protrusions of variable size. Numerous gaps have been found in the capillary wall, specially in the venules. These alterations are not observed in the animals that were treated with calcium dobesilate before the administration of histamine. In these cases the capillary structure are indistinguishable of the controls. The possible effects of the histamine and calcium dobesilate on the cell coat and cell junctions of the endothelial capillary cells are discussed.