Is postextrasystolic potentiation dependent on Starling's law? Biplane angiographic studies in normal subjects

The cineangiograms of 26 normal subjects were analyzed to study the effect of Starling's mechanism on postextrasystolic potentiation. The end-diastolic volumes (single plane and biplane) of the left ventricle were similar in the regular sinus beat before an extrasystole and sequential sinus beats after an extrasystole. However, the ejection fraction, mean normalized systolic ejection rate, mean velocity of fiber shortening and long-axis shortening were consistently larger in the first sinus beat after an extrasystole. We conclude that postextrasystolic potentiation is independent of left ventricular end-diastolic volume in normal human hearts and the compensatory pause after an extrasystole does not result in increased end-diastolic volume.

Uhl's anomaly associated with pulmonary atresia

We present a case of Uhl's anomaly associated with atresia of the pulmonary valve. The rarity of this association is noteworthy, only three cases having previously been published. Our case presents the peculiarity of a patient with a normal tricuspid valve.

Prolonging life with coronary bypass surgery in patients with three-vessel disease

In this study we examined survival after coronary bypass surgery in patients with three-vessel disease. First, survival data were analyzed from selected of patients who had a poor prognosis without surgery; second, data were analyzed in subsets classified by severity of disease. The data strongly suggest that patients with three-vessel disease, especially patient with a poor medical prognosis, benefit from coronary bypass surgery.

Mammary carcinoma--multidisciplinary treatment with bilateral mastectomy and immediate reconstruction

The classical concepts pertaining to the natural history of mammary carcinoma and its treatment must be reviewed if survival rate is to be improved. By the time diagnosis is established, a fair amount of cases of carcinoma of the breast present distant, clinically undetectable micrometastases, which will not be affected by local therapy (surgery or radiation). Increasing evidence shows that mammary carcinoma nowadays must be looked upon as a diffuse disease affecting both breasts. Postoperative radiation does not improve the 5- and 10-year survival rates and has a negative effect upon the immunological defense of the patient. Immunology plays an important role in the evolution and cure of the patient with carcinoma of the breast. The mutilation produced by radical or ultraradical mastectomy may throw the patient into mental depression which, as a consequence, may decrease the immunological competence of the patient. Multiple drug chemotherapy, started at the time of surgery and continued for several months thereafter, may kill micrometastases. Preventive immunotherapy seems to be beneficial to the patient in attempting control of metastases.

Interactions of homologous and heterologous deoxyribonucleic acids and competent Bacillus subtilis cells

Glucosylated and nonglucosylated bacteriophage T4 deoxyribonucleic acids (DNAs) are able to bind to competent cells of Bacillus subtilis, although the former does so in a rather unstable fashion, probably because of the glucosylation. Several heterologous DNAs compete with homologous DNA for the same receptors in binding and in transformation. A different pattern in competition for DNA binding was observed for homologous and T4 glucosylated DNAs in intact cells as compared with protoplasts or membrane vesicles. The results are consistent with the existence of two types of receptor sites on the membrane of competent B. subtilis cells.

Nitrogen control in Salmonella: regulation by the glnR and glnF gene products

The product of the glnR gene is required for nitrogen regulation of the synthesis of glutamine synthesis (Gln synthetase) [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2] and two periplasmic transport proteins that are subject to nitrogen control in Salmonella. Strains with mutations to loss of function of the glnR product [e.g., a strain with a Tn10 insertion or one with an ICR-induced (frameshift) mutation in glnR] have about 3% as much Gln synthetase as a fully derepressed wild-type strain and are unable to increase synthesis of this enzyme or periplasmic transport proteins in response to nitrogen limitation. The structural gene for Gln synthetase, glnA, and those for the periplasmic transport proteins are unlinked on the chromosome; thus, glnR appears to encode a diffusible positive regulatory element. Consistent with this, the mutant glnR allele is recessive to the wild-type allele with regard to expression of glnA (synthesis of Gln synthetase). Although glnR is closely linked to glnA, strains with mutations to complete loss of function of the glnR product can be distinguished from glnA strains by their ability to produce detectable Gln synthetase and to grow in the absence of glutamine. To demonstrate unequivocally that glnR is distinct from glnA, we have purified and characterized Gln synthetase from a strain with a Tn10 insertion in glnR. Because the properties of Gln synthetase from the insertion mutant, most importantly the carboxyl-terminal sequence of amino acids, are the same as those of synthetase from wild type, the Tn10 insertion cannot be in glnA (if it were, the carboxyl terminus of Gln synthetase would have to be altered); therefore we conclude that the Tn10 insertion is in a regulatory gene, glnR, which is distinct from glnA. A model for the function of the glnR product together with the previously defined glnF product in mediating nitrogen control is discussed.

Effect of a physical conditioning program upon left ventricular ejection fractions determined serially by a noninvasive technique

6 clinically normal subjects underwent a 3-month physical conditioning program with the ejection fractions determined before and after physical conditioning using a scintillation probe. All subjects achieved a conditioning effect as evidenced by increased treadmill test duration after conditioning (mean duration before conditioning: 658 vs. 715 sec after conditioning; p less than 0.02). All 6 subjects increased resting ejection fractions after conditioning (mean ejection fraction before conditioning: 54.5 +/- 5.4%; mean ejection fraction after conditioning: 67.0 +/- 9.0%; p less than 0.01). Thus, an aerobic physical conditioning program appears to increase resting ejection fractions in normal subjects.

Associative transfer and stimulus selection in classical conditioning of the rabbit's nictitating membrane response to serial compound CSs

Four experiments were conducted to determine whether in conditioning to a serial compound, CS1-CS2-UCS, there are (a) associative mechanisms operating to extend conditioning beyond the bounds of a CS-UCS contiguity gradient and (b) stimulus selection processes acting to attenuate the potency of CS-UCS contiguity. In Experiments 1 and 2, the CS2-UCS interval was held at .35 sec while the CS1-UCS interval was varied across groups from .75 to 2.75 sec. CS1 test trials revealed substantial CR acquisition at all CS1-UCS intervals. Moreover, Experiment 2 indicated that when the contribution of cross-modal generalization from CS2 to CS1 was factored out, there still remained a substantial level of conditioning, which Experiment 3 indicated was attributable to an associative mechanism like higher-order or sensory conditioning. The observation of CR acquisition at CS1-UCS intervals of 4.75, 8.75, and 18.75 sec in Experiment 4 suggested that serial compound training yields conditioning to CSs located well beyond the single CS contiguity gradient for the rabbit's nictitating membrane response. Experiments 1 and 2 also indicated the presence of stimulus selection processes because, at the shorter CS1-UCS intervals (.75 and 1.25 sec), the levels of test-trial responding to CS2 fell below those observed to the less contiguous CS1.

Associative transfer and stimulus selection in classical conditioning of the rabbit's nictitating membrane response to serial compound CSs

Four experiments were conducted to determine whether in conditioning to a serial compound, CS1-CS2-UCS, there are (a) associative mechanisms operating to extend conditioning beyond the bounds of a CS-UCS contiguity gradient and (b) stimulus selection processes acting to attenuate the potency of CS-UCS contiguity. In Experiments 1 and 2, the CS2-UCS interval was held at .35 sec while the CS1-UCS interval was varied across groups from .75 to 2.75 sec. CS1 test trials revealed substantial CR acquisition at all CS1-UCS intervals. Moreover, Experiment 2 indicated that when the contribution of cross-modal generalization from CS2 to CS1 was factored out, there still remained a substantial level of conditioning, which Experiment 3 indicated was attributable to an associative mechanism like higher-order or sensory conditioning. The observation of CR acquisition at CS1-UCS intervals of 4.75, 8.75, and 18.75 sec in Experiment 4 suggested that serial compound training yields conditioning to CSs located well beyond the single CS contiguity gradient for the rabbit's nictitating membrane response. Experiments 1 and 2 also indicated the presence of stimulus selection processes because, at the shorter CS1-UCS intervals (.75 and 1.25 sec), the levels of test-trial responding to CS2 fell below those observed to the less contiguous CS1.

Early stages in Bacillus subtilis transformation: association between homologous DNA and surface structures

The addition of ethylenediaminetetraacetate to competent cultures of Bacillus subtilis irreversibly inhibited the transformability as well as the cellular binding of DNA. Our results show that the inhibition of DNA binding by ethylenediaminetetraacetate in whole cells, protoplasts, and membrane vesicles is mainly due to a permanent alteration of the DNA receptors. Transformation absolutely requires free magnesium ions, whereas DNA binding is a magnesium-independent step. In contrast to ethylenediaminetetraacetate, the absence of Mg2+ does not irreversibly affect the capacity of the competent cells to be transformed DNA-binding receptors located at the cell surface remain associated with the plasma membrane after protoplasting and after isolation of membrane vesicles. A Mg2+-dependent endonucleolytic activity associated with the membrane appears to be responsible for the lower levels of binding by protoplasts in the presence of this ion.

Late deterioration in tetralogy of Fallot: unusual findings and successful correction

A patient with tetralogy of Fallot who underwent a successful Blalock shunt procedure as a child was evaluated 28 years later because of clinical deterioration. Results of cardiac catheterization and angiography disclosed, in addition to a functioning shunt, evidence of an infundibular, subvalvular tumor and a large anastomosis between the left circumflex coronary artery and the bronchial arteries of the right lung with the possibility of "coronary steal". At operation, the Blalock and coronary-to-bronchial artery anastomoses were ligated; and total correction was performed including resection of the pulmonary valve and infundibulum, excision of the tumor, closure of the ventricular septal defect, and application of an outflow patch to enlarge the pulmonary annulus. The patient was discharged nine days after surgical correction.

Is the treadmill exercise test useful for evaluating coronary artery disease in patients with complete left bundle branch block?

To aid in the study of coronary artery disease, 57 patients with complete left bundle branch block underwent clinical evaluation, treadmill exercise testing and cardiac catheterization. The patients were classified into two groups according to coronary angiographic findings: 30 patients with significant stenosis (70 percent or greater luminal narrowing) of at least one major vessel and 27 with no significant coronary artery disease. There was no difference in age, presenting symptoms or previous medical treatment between the two groups. There were more men in the group with coronary artery disease. Exercise-induced S-T changes were similar in the two groups; the sensitivity and specificity of these changes for the diagnosis of coronary artery disease were unacceptable irrespective of the criterion chosen. With additional S-T depression of either 1 or 2 mm below the baseline value, the predictive accuracy was only 53 percent. Combined exertional chest pain and 1 mm S-T depression increased the predictive accuracy of exercise testing to 71 percent. These data indicate that exercise-induced electrocardiographic changes do not facilitate detection of coronary artery disease in patients with complete left bundle branch block.

Ultrasonic evaluation of thrombosis of Björk-Shiley aortic valve prosthesis

Recognition of thrombosis of a Björk-Shiley aortic valve prosthesis 4 years after insertion in a patient was based upon sudden clinical deterioration, loss of prosthetic sounds, and development of new stenotic and regurgitant murmurs. Thrombotic fixation was confirmed by diagnostic alterations on the echocardiogram. All manifestations reverted to normal after successful surgical debridement of the prosthesis. Echocardiography is a valuable noninvasive adjunct in the differential diagnosis of prosthetic valve malfunction.

The product of a newly identified gene, gInF, is required for synthesis of glutamine synthetase in Salmonella

The product of a newly identified gene, glnF, which is distinct from the glutamine synthetase structural gene (glnA), is required for synthesis of glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming), EC 6.3.1.2[ in Salmonella typhimurium and probably in Escherichia coli. Salmonella strains with ICR (2-chloro-6-methoxy-9-[3-(2-chloroethyl)aminopropylamino]acridine dihyodrochloride)-induced (frameshift) mutations in glnF are glutamine auxotrophs; they have less than 10% oof wild-type glutamine synthetase activity or antigen and are unable to derepress the synthesis of the enzyme. The mutant allele is recessive to the wild-type allele, indicating that the glnF gene encodes a diffusible product. Mutant glnF strains have normal activities of all proteins involved in covalent modification of glutamine synthetase: adenylyltransferase (EC 2.7.7.42), PII, uridylyltransferase, and uridylyl removing enzyme. In addition, they have glutamate synthase (EC 1.4.1.13) and glutamate dehydrogenase (EC 1.4.1.4) activities. Thus, glnF does not encode the structure of any of these proteins. The above evidence suggests that the product of the glnF gene is (or produces) a positive regulatory factor that is required for synthesis of glutamine synthetase; it indicates that auto-regulation cannot account for control of the synthesis of glutamine synthetase in Salmonella.

Growth of coliphage BF23 on rough strains of Salmonella typhimurium: the bfe locus

Coliphage BF23 develops in Salmonella typhimurium rough strains. The phage is neither restricted nor modified by S. typhimurium. The growth patterns of the phage were slightly different in S. typhimurium than in Escherichia coli, although phage propagated on S. typhimurium is identical to the phage propagated in E. coli by several criteria used. Mutants of S. typhimurium resistant to BF23 were isolated and found to map (by P22- and Pl-mediated transduction) in the same position as bfe mutants of E. coli. The order of genes was: metB - argC - bfe - rif - purD - metA. Phage BF23 does not form plaques on smooth S. typhimurium strains, since the phage fails to adsorb irreversibly to smooth cells. Nevertheless, on solid agar, the phage prevents growth of many (but not all) smooth strains. Moreover, UV- and alkali-inactivated phage BF23, although unable to form plaques on sensitive hosts, retains the ability to prevent growth of the host on solid medium. This ability is sensitive to protease and resistant to DNAse and RNase. Heat treatment of the phage causes rapid loss of the cell-growth-preventing-ability whereas the ability to form plaques is lost much more slowly. These results lead to a proposal that phage BF23 virions carry a colicin-like factor that kills sensitive cells.

Influence of several nucleotides on the competence development of Bacillus subtilis

The influence of adenosine-3',5'-cyclic monophosphate (cAMP) and other nucleotides on the competence development of Bacillus subtilis was studied. The stimulation of competence which can be achieved by exposing physiologically low-competent cells to supernatants from highly competent cultures can be inhibited with different cAMP doses. When the same cells were suspended in a minimal medium with cAMP, varying degrees of stimulatin- of competence were observed depending on the time of addition of the drug. This effect is not specific for cAMP. It appears to be correlated to an increase of the amount of DNA bound to the competent cells. cAMP activities were antagonized by equimolar doses of adenosine-triphosphate (ATP) and guanosine-triphosphate (GTP).

Surgical repair of atrial septal defect in patients over 60 years of age. Long-term results

In order to evaluate results of surgical repair of secundum atrial septal defect (ASD) in patients 60 years of age or older, a review was made of 16 patients who had undergone such operation between January 1964 and December 1974. Before operation eight patients were in functional classification III (New York Heart Association), seven were in class II, and one was in class I. Twelve patients had a left-to-right shunt greater than 3:1. Pulmonary artery systolic pressure was greater than 40 mm Hg in 12 patients and greater than 60 mm Hg in five. Four patients had documented paradoxical emboli and were being treated with Coumadin. Before operation all patients but one were receiving digoxin. Repair was accomplished by direct suture in two patients and Dacron patch graft in 14. No deaths occurred during the postoperative period. Postoperatively, ten patients were in class I, five in class II, and one remained in class III. The hospital stay ranged from eight to 20 days (average 11 days). Two patients died one year and another (at the age of 77) five years after surgery. The remaining 13 patients are alive and well three months to 11 years after surgery. We conclude that repair of secundum ASD in patients over the age of 60 is safe, has low morbidity, and produces considerable clinical improvement.

Runaway pacemaker in seven patients: a persisting problem

Runaway pacemaker has been encountered in 7 patients during the past 7 years at the Texas Heart Institute. In this series, 4 patients with fixed-rate pacemakers experienced pacemaker arrhythmias because of battery depletion, and 3 had arrhythmias because of component failure. Battery deterioration was heralded by an increase in cardiac rate. Ventricular tachycardia, rapidly followed by ventricular fibrillation, occurred in 2 patients. Prompt surgical exteriorization of the failing pulse generator and connection to an external pacemaker resulted in prompt recovery in all patients. Elective generator change should be performed routinely after 24 to 30 months unless reliable serial observations of ventricular rates can be attained. This at least will reduce the lethal complications attributed to battery exhaustion. Increasing developments in the design of generators and sources of power, as well as data from pacemaker clinic follow-up and telephone pulse transmittal, are expected to decrease the frequency of this complication.

Pulmonary artery compression due to acute dissecting aortic aneurysm: clinical and angiographic diagnosis

Clinical and angiographic features simulating acute massive pulmonary embolism, the result of compression of the right and main pulmonary arteries by a dissecting hematoma, are described in a 52-year-old white woman.

Treadmill exercise testing in the presence of digitals therapy or nonspecific ST-T changes: correlation with coronary angiography

Treadmill exercise test results were studied in 93 patients with chest pain who had received digitalis therapy or had nonspecific ST-T changes in the resting electrocardiogram. Results of the treadmill test were correlated with the findings of coronary angiography. A positive treadmill result was defined as horizontal or down-sloping ST segment depression greater than or equal to 1.0 mm. Of the 40 patients with no or insignificant coronary artery disease, 15 had taken digitalis; 4 of the 15 demonstrated a positive response on the treadmill test. Of the 53 patients with coronary artery disease, 21 had taken digitalis; 15 of the 21 displayed a positive response. Among the remaining 32 not on digitalis, 20 had a positive response. The specificity of the treadmill exercise test was 96% in patients with coronary artery disease not on digitalis and whose resting electrocardiogram showed nonspecific ST changes. The specificity of the treadmill test in patients who had received digitalis was 73%. Sensitivity was 63% and 71%, respectively. By utilizing more stringent criteria in the interpretation of the treadmill exercise test (greater than or equal to 1.5 mm ST depression), among the patients on digitalis only 6.7% (1/15) with normal coronary arteries and 48% (10/21) with coronary artery disease had a positive response. With the use of the latter criterion the test was specific in 93% (14/15) of the patients and is usually indicative of coronary artery disease.

Evaluation of different antibiotic actions combined with rifampicin. In vitro synergism against Pseudomonas and Proteus

Associations of penicillin, streptomycin, tetracycline and polymyxin B with rifampicin were tested for synergism against Pseudomonas and Proteus pathological strains. The combination of rifampicin and polymyxin B was clearly synergistic for all strains as it was evaluated by isobolograms and killing curvesmthe bactericidal action of this association, without any cross-resistance between its components, may eradicate gram-negative bacteria infections with marked polyvalent drug resistances.

Image analysis using enhanced spatial correlation functions

By enhancing the high frequencies of the irradiance spectrum of a scene, it is possible to reconstruct an enhanced self-correlation function that clearly delineates its nondifferentiable regions. The technique has application in image analysis and pattern recognition. By way of example, the enhanced self-correlation function of a certain random process is furnished. Easily discernible are certain periodicities not apparent in the sample functions of the original process.

Use of a diffuser for producing texture masks for image processing

The use of a diffuser in synthesizing binary texture-variance masks for applications in image processing is investigated. The binary texture-variance masks are used to separate various objects in an image on the basis of their spatial texture variance. The diffuser is required to reduce the speckling present in the mask. The reduction in speckling is described quantitatively as a reduction of the misclassification probability associated with the separation of the objects into several texture classes. General results are furnished for the statistics of the field scattered by the diffuser, and these are used to obtain expressions for the misclassification probabilities in the presence of a diffuser. Some applications are furnished.

The training and generalization of a conversational speech form in nonverbal retardates

Differential reinforcement and imitation were used with two retarded children to train three sequential verbal responses associated with the display of a picture and questions related to that picture. Each response consisted of a three-word chain in sentence form; combined with verbal responses from the experimenter, this trained sequence formed a short conversational unit. Three experimenters measured the use of each sentence in settings different than the one in which training took place, and with pictures different than those used during training. Two types of generalization sessions were used: (1) General sessions, during which 10 pictures never used during training were displayed to the subject with reinforcement delivered on a noncontingent basis, and (2) Intermixed sessions, during which 10 pictures never used during training were displayed to the subject, but a picture having received training was also displayed, and correct responses to this picture were reinforced on a variable schedule. Both subjects learned the sentences being trained. However, little generalization was evident from this training when all experimenters conducted General probe sessions. Generalization occurred with one experimenter only after that experimenter conducted Intermixed probe sessions. Generalization to a third experimenter was then observed (i.e., after the first two experimenters had conducted Intermixed probe sessions) without the use of Intermixed probe sessions by this third experimenter.

Coronary artery bypass

From October 1969 through March 1972, 1,276 patients underwent coronary artery bypass at the Texas Heart Institute. Associated conditions included simultaneous valve replacement and resection or repair of ventricular aneurysms or ascending aortic aneurysms. Among the series were 1,105 patients who underwent bypass surgery alone, with or without endarterectomy.

Factors affecting outcome were analyzed and revealed adverse influences including concomitant endarterectomy, female sex, age, evidence of left ventricular failure or serious ventricular dysfunction, and previous myocardial infarction within the month before surgery, but more importantly within the week prior to surgery. Functional class III and IV angina was significantly decreased or totally relieved in a high percentage of patients after bypass surgery, and remains the major indication at this time for myocardial revascularization. Progressive reduction in surgical risk and improvement in patient selection allow coronary artery bypass to be performed currently with an early mortality risk of only 3.7%.

Atresia of the left coronary artery ostium. Repair by saphenous vein graft

Symptoms and electrocardiographic changes of acute myocardial ischemia in a 10-year-old boy resulted from congenital atresia of the ostium of the left coronary artery. At 14 years of age persistence of symptoms and a positive exercise test prompted surgical treatment by aortocoronary artery saphenous vein bypass graft. Two months postoperatively, the symptoms and the abnormal findings on exercise test had subsided and forward flow through the graft to the left coronary artery was demonstrated by contrast angiography.

Variance measurements by a coherent optical method, with application to image processing

A procedure for measuring the point-to-point local variance of a spatial random scene is discussed. The relations that are required between the second-order statistics of the random process and the parameters of the optical configuration to furnish accurate and stable variance estimates are established. The procedure is experimentally verified by using calibrated samples of the random checkerboard and the overlapping circular grain models. A modification of the procedure enables the generation of spatial masks that are useful in automatic image processing. The spatial masks are used as binary spatial gates to isolate certain classes of objects within a scene and reject all others. Typical masks are synthesized and their applications illustrated.