Impact of increased infarct transmurality on remodeling and function during healing after anterior myocardial infarction in the dog

To determine the impact of greater infarct transmurality on changes in left ventricular remodeling and function after acute anterior myocardial infarction, serial topographic and functional parameters (two-dimensional echocardiograms) and hemodynamics over 6 weeks, and postmortem topography (planimetry) at 6 weeks, were measured in chronically instrumented dogs randomized to standard coronary artery ligation (group 1) or a modified lower ligation plus collateral obliteration to decrease collateral inflow and increase transmurality (group 2). At 6 weeks, postmortem scar size and collagen were similar in the two groups, but group 2 had greater transmurality associated with more necrosis relative to area at risk, Q waves, infarct expansion, thinning, regional bulging, and cavity dilatation. Over the 6 weeks, group 2 showed more early expansion, late thinning and regional bulging in the short axis, larger diastolic and systolic volumes, and more apical aneurysmal bulging in the long-axis, reflecting more topographic deterioration. More important, group 2 showed greater regional and global left ventricular dysfunction over 6 weeks, lower ejection fraction at 2 days with further decrease over 6 weeks, and more left ventricular thrombus, ventricular arrhythmias, and deaths. In addition, transmurality correlated with the severity of remodeling and dysfunction. The findings indicate that transmurality is a major determinant of remodeling and left ventricular dysfunction during healing after anterior infarction.

Effect of left ventricular unloading with captopril on remodelling and function during healing of anterior transmural myocardial infarction in the dog

OBJECTIVE

To determine whether left ventricular (LV) unloading with captopril between two days and six weeks during healing after transmural anterior acute myocardial infarction might prevent further LV remodelling and preserve function in the canine model.

DESIGN

Serial LV topographic and functional parameters (two-dimensional echocardiograms) and hemodynamics over six weeks and scar topography (planimetry) and collagen (hydroxyproline) at six weeks were measured in 34 chronically instrumented dogs; 24 with anterior transmural acute myocardial infarction (coronary artery ligation and collateral obliteration) that had been randomized at two days post infarction to therapy with oral 50 mg bid placebo (n = 12) or captopril (n = 12) for six weeks, and 10 with sham infarction.

MAIN RESULTS

At six weeks, captopril and placebo groups had similar scar mass (7.7 versus 8.1% LV), infarct hydroxyproline and transmurality but the captopril group showed significantly less (P less than or equal to 0.05) infarct expansion and thinning, cavity dilation, epicardial and endocardial bulge. Between two days and six weeks, captopril decreased mean left atrial and arterial pressures compared to placebo or sham. Echocardiograms at two days showed similar LV asynergy, ejection fraction, infarct expansion and thinning with placebo and captopril. In contrast, echocardiograms between two days and six weeks showed that: further expansion and thinning occurred with placebo but not captopril; LV volumes increased with placebo but decreased with captopril; total LV asynergy was unchanged with placebo but decreased with captopril; and LV ejection fraction was unchanged with placebo but increased with captopril. At six weeks, LV ejection fraction was 10% higher (45 versus 35%, P less than 0.001) and LV aneurysm was less frequent (33 versus 100%, P less than 0.005) with captopril compared to placebo.

CONCLUSIONS

Chronic LV unloading with captopril therapy during healing after canine transmural anterior acute myocardial infarction limits further remodelling, decreases aneurysm formation and improves function.

Effect of long-term captopril therapy on left ventricular remodeling and function during healing of canine myocardial infarction

To determine whether the long-term reduction of preload and afterload by captopril during healing after acute anterior myocardial infarction might attenuate left ventricular remodeling and improve function, 30 chronically instrumented dogs with infarction produced by left anterior descending coronary artery ligation were randomized 2 days later to oral therapy with placebo (n = 15) or captopril, 50 mg twice daily (n = 15), for 6 weeks. Serial hemodynamic as well as topographic and functional variables (two-dimensional echocardiography) were measured over 6 weeks. Scar topography (planimetry), occluded bed size (coronary arteriography) and collagen (hydroxyproline) content were measured at 6 weeks. Between 2 days and 6 weeks, captopril decreased (p less than 0.001) mean arterial pressure and mean left atrial pressure more than did placebo, but it did not influence heart rate. Infarct scar mass, transmurality and collagen content at 6 weeks were similar in the two groups but scars showed less (p less than 0.001) thinning and expansion with captopril than with placebo. Echocardiograms showed similar infarct expansion and thinning in the two groups at 2 days but less aneurysm with captopril at 6 weeks. Between 2 days and 6 weeks, expansion index (infarct-/noninfarct-containing segment length) decreased (p less than 0.001) with captopril but increased (p less than 0.001) with placebo. Also, thinning ratio (infarct/normal wall thickness) decreased (p less than 0.001) with placebo but did not change (p = NS) with captopril. By 6 weeks, left ventricular asynergy and volumes showed a greater decrease (p less than 0.01) and global ejection fraction a greater increase (p less than 0.05) with captopril.(ABSTRACT TRUNCATED AT 250 WORDS)

Predicting recovery of facial nerve function following injury from a basilar skull fracture

Twenty-five patients with posttraumatic facial nerve palsy were studied. Partial recovery of function had occurred in 95% of these patients by 18 months after injury. At 5 months posttrauma, there was some recovery in 92.5% of those with a partial lesion compared with 10% of those with a complete lesion. This difference attains statistical significance. Complete recovery of nerve function had occurred by 10.5 months in 53.5% of the patients; in 62% of patients with a partial lesion, complete recovery had occurred by 4 months compared with 0% in those with a complete lesion. This difference also attains statistical significance. There was no statistically significant difference in recovery of function between patients with an immediate as opposed to a delayed onset of facial nerve palsy. It was determined that the degree of palsy had a statistically significant influence on recovery of facial nerve function, whereas the time of onset did not. The data presented support a conservative approach to these injuries and it is recommended that the possibility of surgical treatment should be entertained in patients with complete facial palsy persisting for 12 to 18 months after injury.

The use of the probit model to predict pregnancy status of buffalo based on physio-chemical properties of estrual mucus

Improper timing of artificial insemination with respect to ovulation is one of the major factors hampering the conception rate in buffalo. The present study was an attempt to relate physio-chemical changes in estrual mucus to subsequent pregnancy status in order to find their optimal values for determining the time for artificial insemination (AI). Serum estradiol, total protein and dry matter contents of estrual mucus were evaluated to predict the subsequent pregnancy in 36 buffalo during October 1988 to February 1989. Serum estradiol was determined by radioimmunoassay (RIA); spinnbarkeit, dry matter and total protein were determined by standard methods. Multivariate probit analyses were carried out to relate these variables to subsequent pregnancy status. Elasticity and protein concentration were significantly related to prediction probability of pregnancy status, and they predicted the pregnancy status 86% of the times correctly (P<0.05). The probability of pregnant animals being correctly classified was 0.76, whereas the corresponding value for non-pregnant animals was 0.95. The present study demonstrated the possibility of using such a statistical model on mucus characteristics for determining proper AI time for better conception rates in Nili-Ravi water buffalo.

Interactions of concanavalin A with glycoproteins. A quantitative precipitation study of concanavalin A with the soybean agglutinin

Certain oligomannose-type glycopeptides have been previously shown to be bivalent for binding to concanavalin A and capable of precipitating the lectin by forming homogeneous cross-linked lattices [L. Bhattacharyya, M. I. Khan, and C.F. Brewer, Biochemistry, 27 (1988) 8762-8767]. In the present study, the effect of protein environment on the binding properties of an oligomannose-type oligosaccharide has been examined through quantitative precipitation analysis of the interactions of concanavalin A (Con A) with the soybean (Glycine max) agglutinin (SBA), which is a tetrameric glycoprotein possessing a single Man9-oligomannose chain per monomer. The results showed that SBA forms two different types of cross-linked complexes with tetrameric Con A, depending on the relative ratio of the two molecules in solution. At a concentration of one equivalent or less, SBA forms a 1:1 complex with Con A. At concentrations exceeding one equivalent, SBA forms a 2:1 complex with Con A. However, SBA forms only 1:1 cross-linked complexes with dimeric forms of Con A, such as acetyl- and succinyl-Con A. The results demonstrated that the total valency of the carbohydrate of SBA is a function of both the quaternary structure of Con A, as well as the relative ratio of SBA to Con A. In addition, the individual Man9-oligosaccharide, which as a glycopeptide is bivalent for binding to Con A, expresses univalency when present on the protein matrix of SBA.

Characteristics of an unusual mycoplasma isolated from a case of caprine mastitis and arthritis with possible systemic manifestations

A mycoplasma designated strain GM790A was isolated from milk and internal organs of 2 lactating goats showing mastitis and arthritis. The isolate was not related serologically to any of the currently known ovine-caprine mycoplasmas, except an isolate designated Mycoplasma sp. G, first recorded from the external ear canal of clinically normal goats in Australia. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and restriction enzyme DNA studies of strain GM790A and Mycoplasma sp. G revealed similar but not identical patterns. The inoculation of strain GM790A into the teat canal of 2 lactating goats resulted in an abrupt diminution of lactation leading to mastitis and agalactia in about 3 days. A maximum of 1 x 10(7) colony-forming units (CFU) of the mycoplasma were shed per ml of mammary secretion. Milk production partially resumed at a low level 3 weeks postinoculation, the longest period tested, but the milk still contained 1 x 10(2) CFU of the agent. The results of this study indicate that strain GM790A possesses pathogenic potential for the goat and most probably represents a new species of the genus Mycoplasma.

Early coronary reperfusion blunts the procoagulant response of plasminogen activator inhibitor-1 and von Willebrand factor in acute myocardial infarction

The effects of early coronary recanalization on the plasma levels of two procoagulant acute phase proteins, the fastacting plasminogen activator inhibitor and von Willebrand factor, were investigated in 24 patients with myocardial infarction receiving intravenous recombinant tissue-type plasminogen activator (rt-PA) within 6 h of the onset of symptoms. Coronary angiography was performed before and 90 min after the start of rt-PA infusion. Continuous electrocardiographic recordings and 4 h plasma creatine kinase MB isoenzyme (CK MB) were performed over the first 24 h. Plasma plasminogen activator inhibitor activity, von Willebrand factor and C-reactive protein were measured before rt-PA infusion, daily for the first 3 days and after 90 days. In the entire group, plasminogen activator inhibitor activity peaked at 24 h (day 1), representing a significant increase over values at all other times (p = 0.03). von Willebrand factor was higher in the first 2 days of infarction compared with after 90 days (p = 0.001). C-reactive protein peaked on day 2, with an eightfold increase over values on admission (p = 0.001). In the 16 patients with a patent infarct-related artery at 90 min, infarct size estimated by integrated 24 h CK MB, time for ST segment elevation to decrease to half-maximum and peak C-reactive protein were reduced significantly by more than twofold compared with values in the 8 patients with an occluded artery at 90 min. The patients with early recanalization also had lower plasminogen activator inhibitor activity on day 2 (p = 0.05) and day 3 (p = 0.02) and lower 0 to 72 h averaged von Willebrand factor (p = 0.01). Thus, early coronary recanalization curtails the response of plasminogen activator inhibitor activity and von Willebrand factor to myocardial infarction, most likely by reducing the extent of ischemia and necrosis and the consequent acute phase reaction. By blunting the early postinfarction procoagulant state, prompt recanalization may reduce the risk of thromboembolic complications in the first days after myocardial infarction.

Effect of reactor retention on the spread of brucellosis in Jersey cattle and buffalo herds

The rate of spread of bovine brucellosis was investigated in buffalo and Jersey cattle herds maintained at a Livestock Research station in Pakistan. Reactor animals (identified by conventional serological tests) were either retained or culled because of advanced age or poor productivity. Reactors were housed, managed and fed separately from the rest of the herds. The initial seroprevalence of brucellosis among both the Jersey cattle and the buffalo tested was 21.4%, the difference being statistically insignificant (p = 0.218). For 34 months, the spread of brucellosis was limited to 25 new reactors in the 334 cows and 33 in the 442 buffaloes. The mean attack rate was 7.5% for both herds during the test intervals. Trend analysis of proportions positive at each testing revealed a significant decrease in the percentages observed at the first testing. The management practice of segregation offered some advantage in reducing the spread of brucellosis to negative animals. However, an epidemiological study covering a large number of herds would be required to identify risk factors responsible for perpetuating the disease.

Photoacoustic "Signatures" of Particulate Matter: Optical Production of Acoustic Monopole Radiation

Absorption of pulsed laser radiation by a single particle generates a photoacoustic wave whose time profile can be measured with a wideband pressure transducer. Solution of the wave equation for pressure in one, two, and three dimensions shows that the photoacoustic wave is determined by the geometry and dimensions of the particle, and by its sound speed and density relative to the fluid that surrounds it. Photoacoustic waves, referred to here as signatures, are reported in experiments in which fluid droplets, cylinders, and layers are irradiated with 10-nanosecond laser pulses.

Fingerprinting of Mycoplasma gallisepticum strains isolated from multiple-age layers vaccinated with live F strain

Mycoplasma gallisepticum (MG) isolates were obtained from three multiple-age commercial layer farms on which live F strain vaccine had been administered to each replacement flock for at least 2 years. All such isolates had restriction endonuclease DNA and sodium dodecyl sulfate-polyacrylamide gel electrophoresis protein patterns characteristic of F strain. These cultures also hybridized in dot blot assays with both the MG strain-specific and species-specific DNA probes. In contrast, the original MG isolate that came from one of the farms before vaccination began clearly was not F strain. These results suggest that continuous use of live F strain vaccine in each replacement pullet flock on multiple-age commercial layer sites will result in displacement of the original field strain of MG with the vaccine strain.

Photoacoustic generation of anisotropic pressure waves through photodissociation of Cl(2)

Photodissociation of diatomic molecules by linearly polarized radiation in general produces an anisotropic distribution of recoiling atomic fragments. When a short burst of radiation dissociates a gas at low pressure, the collective linear momenta of the individual recoiling photofragments add at any point in space to act as a macroscopic pressure wave, the impulse corresponding to which can be detected by a sensitive microphone. We report here detection of anisotropic pressure waves from photodissociation of Cl(2) with 355-nm radiation. The experimental data show the pressure wave to be peaked in a direction perpendicular to the polarization direction of the incident radiation, indicating a predominantly perpendicular transition moment in Cl(2) at this wavelength.

Effectiveness of multiple bolus administration of tissue-type plasminogen activator in acute myocardial infarction

The feasibility and possible advantages of intravenous bolus administration of recombinant tissue-type plasminogen activator (rt-PA) were investigated in 26 consecutive patients with early (less than 6 hours) evolving acute myocardial infarction. Either an intravenous infusion of 40 clot-lysis megaunits (cIMU) double-chain rt-PA over 1.5 hours followed by 20 cIMU over 5 hours (infusion group, n = 12) or 4 intravenous bolus injections of 10 cIMU at 20 minute intervals (bolus group, n = 14) were randomly administered. Coronary arteriography was performed before and at regular predefined intervals up to 90 minutes from the start of rt-PA administration, and at 24 hours. Acute recanalization of the infarct-related coronary artery was demonstrated in 7 of 12 patients (58%; 95% confidence interval 28 to 85%) in the infusion group and 11 of 14 patients (79%; 95% confidence interval 49 to 95%) in the bolus group (difference not significant). Two patients in the bolus group had reoccluded by 24 hours. Mean time from the start of rt-PA to patency of the infarct-related coronary artery was 39 +/- 6 (standard error of the mean) minutes in the infusion group and 28 +/- 6 minutes in the bolus group (p = 0.2). There were no significant differences in the minimum infarct-related coronary artery luminal diameter measured by computerized quantitative arteriography between the infusion group and the bolus group at 90 minutes or at 24 hours.(ABSTRACT TRUNCATED AT 250 WORDS)

Formation of highly ordered cross-linked lattices between asparagine-linked oligosaccharides and lectins observed by electron microscopy

The interaction of asparagine-linked carbohydrates (N-linked) with carbohydrate binding proteins called lectins has been demonstrated to be involved in a variety of cellular recognition processes. Certain N-linked carbohydrates have been shown to be multivalent and capable of binding, cross-linking, and precipitating lectins (Bhattacharyya, L., Ceccarini, C., Lorenzoni, P., and Brewer, C. F. (1987) J. Biol. Chem. 262, 1288-1293; Bhattacharyya, L., Haraldsson, M., and Brewer, C. F. (1987) J. Biol. Chem. 262, 1294-1299; Bhattacharyya, L., Haraldsson, M., and Brewer, C. F. (1988) Biochemistry 27, 1034-1041). Recent data have further suggested that certain oligomannose and bisected hybrid-type N-linked glycopeptides form homogeneous cross-linked lattices with concanavalin A (Bhattacharyya, L., Khan, M. I., and Brewer, C. F. (1988) Biochemistry 27, 8762-8767). In the present study, evidence has been obtained from electron microscopy for the formation of highly ordered and distinct lattices for two bivalent complex type oligosaccharides cross-linked with soybean lectin (Glycine max) and isolectin A from Lotus tetragonolobus, respectively. The results indicate a new source of specificity for interactions of N-linked carbohydrates with lectins, namely their ability to form highly ordered homogeneous aggregates.

Differentiation of the vaccine F-strain from other strains of Mycoplasma gallisepticum by restriction endonuclease analysis

The electrophoretic patterns of the nucleic acids (DNA) of Mycoplasma gallisepticum strains digested with the restriction enzymes Bam HI, Eco RI and Hind III were useful for differentiating the vaccine F-strain from other strains of M. gallisepticum. The procedure was more sensitive than the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) technique. The vaccine F-strain, represented by cultures designated F-K810 and F-F2F10 was clearly differentiated from other strains of M. gallisepticum. This procedure may be useful in field studies to determine if the vaccine strain will replace wild-type M. gallisepticum in commercial layers.

Antigenic analysis of three strains of Mycoplasma meleagridis of varying pathogenicity

Three strains of Mycoplasma meleagridis of varying pathogenicity were characterized by conventional serologic methods and by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The three strains (RY-39A, MC-25B, and RY-39C) did not differ by cross agglutination, immunofluorescence and immunodiffusion tests. However, the strains differed in their protein patterns as determined by SDS-PAGE.

Interactions of concanavalin A with asparagine-linked glycopeptides: formation of homogeneous cross-linked lattices in mixed precipitation systems

We have previously shown that certain oligomannose and bisected hybrid type glycopeptides are bivalent for binding to concanavalin A (Con A) [Bhattacharyya, L., Ceccarini, C., Lorenzoni, P., & Brewer, C. F. (1987) J. Biol. Chem. 262, 1288-1293]. Each glycopeptide gives a quantitative precipitation profile with the protein which consists of a single peak that corresponds to the binding stoichiometry of glycopeptide to protein monomer (1:2). We have shown that the affinities of the primary and secondary sites of the glycopeptides influence their extent of precipitation with the lectin [Bhattacharyya, L., & Brewer, C. F. (1988) Eur. J. Biochem. (in press)]. In the present study, we demonstrate that equimolar mixtures of any two of the glycopeptides result in a quantitative precipitation profile which shows two protein peaks. Using radiolabeled glycopeptides, the precipitation profiles of the individual glycopeptides were determined. The results show that each glycopeptide forms its own precipitation profile with the protein which is independent of the profile of the other glycopeptide. For mixtures containing an equimolar ratio of two glycopeptides, the glycopeptide with lower affinity shows a precipitation maximum at a lower concentration than the one with higher affinity. However, this can be reversed by increasing the ratio of the lower affinity glycopeptide in the mixture. Thus, the relative precipitation maxima of the glycopeptides are determined by mass-action equilibria involving competitive binding of the two carbohydrates to the protein. These equilibria, in turn, are sensitive to the relative amounts and affinities of the carbohydrates at both their primary and secondary sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Ubiquitin-metallothionein fusion protein expression in yeast. A genetic approach for analysis of ubiquitin functions

We have established a Saccharomyces cerevisiae genetic system that expresses the fusion protein ubiquitin-metallothionein. We have evaluated the effects of amino-terminal ubiquitination of metallothionein on the stability and function of metallothionein. The fusion protein of wild type ubiquitin and metallothionein was rapidly processed in vivo to release free ubiquitin and metallothionein. Site-directed mutants of ubiquitin-metallothionein expressed in yeast were used to study the specificity of the (alpha-NH2-ubiquitin) protein endopeptidases. The data suggest that amino-terminal ubiquitination is not a signal for the proteolysis of yeast metallothionein in yeast. We have also discovered that expression of selected ubiquitin mutants blocked the growth of yeast. The data suggest that in addition to its function as a proteolytic signal, ubiquitination of proteins plays multiple roles in the cell.