Acid tolerance response and survival by oral bacteria.

Using 21 species of oral bacteria, representing six acidogenic genera, we undertook to determine whether the pH-limiting exponential growth is related to the ability of the organisms to generate an acid-tolerance response that results in enhanced survival at low pH. The lower pH limit of exponential growth varied by more than two units with that of Neisseria A182 at pH 6.34; growth of Lactobacillus casei RB1014 stopped at pH 3.81, with species of Actinomyces, Enterococcus, Prevotella and Streptococcus falling between these limits. The working hypothesis was that the organisms with the higher pH limits for growth are unable to respond to acidic environments in order to survive, whereas the more aciduric organisms would possess or acquire acid tolerance. Adaptation to acid tolerance was tested by determining whether the prior exposure of exponential-phase cells to a low, sub-lethal pH would trigger the induction of a mechanism that would enhance survival at a pH killing pH 7.5 control cells. The killing pH varied from pH 4.5 for Prevotella intermedia ATCC 25611 to pH 2.3 for the three Lactobacillus casei strains in the study, with the three Streptococcus mutans strains killed at pH 3.0 for 3 h. The adaptation experiments revealed three groups of organisms: non-acid-responders, generally representing strains with the highest terminal pH values; weak acid-responders in the middle of the pH list, generating low numbers of survivors at one or two pH values, and the aciduric, strong responders generating a high number of survivors at pH values in the range 6.0 to 3.5, but not at pH 7.5. Predominant among the latter group were the S. mutans and Lactobacilli casei strains, with the most significant adaptive response exhibited by S. mutans LT11 and S. mutans Ingbritt, involving a process that required protein synthesis. Time course experiments with the latter organisms indicated that 90-120 min was required after exposure to the triggering pH before the acid response was fully functional. These results indicate that the sudden exposure of strains of oral streptococci and lactobacilli, as well as Enterococcus faecalis, to pH values between 6.0 and 3.5 results in the induction of an acid tolerance response that enhances the survival of these strains at or below pH 3.5.

Atrial septal aneurysm associated with systemic embolism and interatrial right-to-left shunt.

Prior to the advent of two-dimensional echocardiography, atrial septal aneurysm was rarely diagnosed during life. In this article, two-dimensional echocardiography identified an atrial septal aneurysm as the site of intracardiac right-to-left shunting, causing hypoxemia in a patient with acute right ventricular infarction. In addition to this rare presentation, the patient also had systemic embolism, a known complication of atrial septal aneurysms.

Hypertrophic cardiomyopathy in the elderly. A frequently misdiagnosed disease.

In 20 elderly patients (mean age, 76 years; range, 70 to 86 years), hypertrophic cardiomyopathy was diagnosed echocardiographically. Although the disease was moderate to severe in all patients, the diagnosis was not suspected in 19 patients prior to echocardiography. Inappropriate therapy consisting of potentially harmful drugs, such as digitalis, nitrates, and diuretics, was commonly used, often for unclear indications. Since echocardiography can easily and accurately diagnose hypertrophic cardiomyopathy, an increased awareness of its occurrence in the elderly and use of echocardiography would reduce diagnostic and therapeutic errors.

ST segment depression in acute anterior myocardial infarction.

We initiated a retrospective study to determine whether ST segment depression seen in inferior leads (II, III, and aVF) during acute anterior myocardial infarction (MI) is a reciprocal change or an independent sign of ischemia of additional myocardium. We selected 20 patients with anterior MI and attempted to compare findings of subsequent cardiac catheterization and the clinical course of 14 patients with ST segment depression (group A) and six without ST segment depression (group B). Patients in group A had a higher prevalence of right coronary artery disease (13 vs 0, P less than .01), multivessel disease (14 vs two, P less than .01), inferior wall motion abnormalities (seven vs 0, P less than .01), and ejection fraction of less than .50 (ten vs two, P greater than .05) than those in group B. A greater number of patients in group A had serious in-hospital and follow-up complications (12 vs two, P less than .05). We conclude that ST depression in leads II, III and aVF during acute anterior MI is not "reciprocal change" but a high-risk indicator.

The psychological impact of menarche on early adolescent females: a review of the literature.

This paper reviews research on the psychological impact of onset of menstruation (menarche). Menarche is an important event for all girls, yet there is relatively little research on this topic, and the existing research contains a number of conceptual and methodological problems. In this paper, we review attitudes toward menarche and personality characteristics of pubertal girls. Then we look at memories of menarche from late adolescents and adult women. Finally, we examine studies of the impact of timing (early and late menarche). Overall, the studies indicate that menarche is a memorable and significant event for girls. Frequently the experience is perceived negatively, but there is also a positive, integrating result to menarche. Factors influencing the psychological impact of menarche include age at time of first period, social factors, amount of preparation, and cultural factors. The paper focuses on research problems and provides suggestions for future research.

PIP: Menarche is an important event for all girls, yet there is relatively little research on this topic, and the existing research contains a number of conceptual and methodological problems. In this paper, attitudes toward menarche and personality characteristics of pubertal girls are reviewed, and memories of menarche from late adolescent and adult women are examined. Studies of the impact of timing (early and late menarche) are also reviewed. The study indicates that menarche is a memorable and significant event for girls. Frequently the experience is perceived negatively, but there is also a positive, integrating result to menarche. Factors influencing the psychological impact of menarche include age at time of 1st period, social factors, amount of preparation, and cultural factors. Research problems and suggestions for future research are noted.

[Comparative investigations of osteotropic isotopes. i animal experiments on the uptake of 18f, 85sr and 99mtc-ehdp (author's transl)]. / Vergleichende Untersuchungen mit osteotropen Radiopharmaka. I. Tierexperimentelle Untersuchungen zur Anreicherung von 18F, 85Sr und 99mTc-EHDP

In normal rabbit bones, as well as in callus, there is significantly more uptake of 18F than of 85Sr or 99mTc-EHDP. Extraosseous abscesses show significantly higher uptake of 99mTc than of 18F or 85Sr. In the presence of hyeraemia, there is no significant difference in the uptake of the various osteotropic radio-nucleides.