Assessment of Aortic Coarctation and Collateral Circulation By Biplane Transesophageal Echocardiography

Our experience in using biplane transesophageal echocardiography in the assessment of coarctation of the aorta is described.     

A comparative conformational analysis of thimet oligopeptidase (EC 3.4.24.15) substrates

The specificity of thimet oligopeptidase (EC 3.4.24.15) (TOP 24.15) does not agree with theoretical models devised to explain the specificity characteristic of peptidases toward certain sequences of amino acid residues. According to previous studies peptide chains hydrolyzed by TOP 24.15 adopt similar main chain conformations, although with different and in some cases small probabilities of occurrence in aqueous solution. To determine specific structural features recognized by TOP 24.15, a conformational search including eight polypeptides with known susceptibilities for catalytic hydrolysis was executed and the distribution of each main chain conformation found in the search was tabulated. Two sets of main chain conformations were selected, those common to all peptides in the study and those common only to substrates of TOP 24.15. The former set is very small and includes mainly extended conformations. In contrast, the latter set is large and its conformations are coiled and exhibit sharp turns coincident with positions of hydrolysis by TOP 24.15. These results indicate a possible basis for the selectivity of TOP 24.15.     

Synthesis of human angiotensinogen (1-17) containing one of the putative glycosylation binding sites and its hydrolysis by human renin and porcine pepsin

The N-terminal heptadecapeptide of human angiotensinogen (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu-Val-Ile-His-Asn-Glu-Ser-Thr-NH₂), with the C-terminal carboxyl group amidated, was synthesized in order to study the role of Asn-Glu-Ser, a putative carbohydrate binding site, on the hydrolysis by human renin. The synthesis was performed by fragment condensation using the Honzl and Rudinger azide procedure. In our conditions for azide segment condensation, histidine racemization was demonstrated to be negligible for most of the condensation reactions. Human renin liberates angiotensin I from h-angiotensinogen (1-17)-NH₂ with a K_m value of 3.4 × 10^?5m , at pH 7.3 and 37° being similar to h-angiotensinogen (1-13), an analog without the carbohydrate binding site. However, the V_max value of 4.1 × 10^?9mol/G.U. min is one order of magnitude higher. Porcine pepsin was demonstrated to cleave preferentially Leu¹⁰-Val¹¹ bond and, surprisingly, His⁹-Leu¹⁰ as well.     

Prevalence of Noncarious Cervical Lesions and Their Relation to Occlusal Aspects: A Clinical Study

Purpose: The purpose of this study was to assess noncarious cervical lesions in young patients and to establish a possible relation with occlusal aspects.
Materials and Methods: Forty-eight dental students (28 males; 20 females) between the ages of 16 and 24 years, were investigated to verify the presence of noncarious cervical lesions and their relation to some occlusal aspects. The assessment involved a questionnaire, clinical examinations, and model analysis.
Results: The results indicated that the lower first molars (21.3%), the upper first molars (16.0%), the upper first premolars (12.8%), the lower first premolars (11.7%), and the lower second premolars (11.7%) were the teeth most affected by the lesions. Age was a significant factor with respect to the presence of lesions; the students with noncarious cervical lesions were older than the students who showed no lesions. Among the 79 teeth exhibiting lesions, 62 (78.5%) showed wear facets. In the group with lesions, the mean, per subject, was 15.0 teeth with wear facets, whereas in the group without lesions the mean was 10.8 teeth with wear facets per subject, suggesting that occlusal stress has some effect on lesion development.
CLINICAL SIGNIFICANCE
Noncarious cervical lesions are characterized by loss of tooth structure on the cervical area of the tooth and can result in esthetic problems for the patient, as well as discomfort due to the hyper-sensibility that often occurs at the location of the lesion. The results obtained reinforce the multifactorial theory, shared by several authors, for the etiology of such lesions. However, as the limitations of each etiologic agent begin to be understood, there will be a decrease in the possibility of misleading interpretations of the result of present or future investigations.     

Transgastric Ultrasonography: A New Approach for Imaging the Abdominal Structures and Vessels

For the first time, the feasibility of using transgastric ultrasonography to examine the abdominal vasculature and organs has been demonstrated. An illustrative case report details how this approach was utilized in a patient following abdominal aortic aneurysm resection, in whom surface ultrasonography was not feasible. The diagnostic potential of this new approach is discussed. Possible modifications to improve the technique and to facilitate the examination in a wider range of patients are also suggested. Further studies are needed to better define the technique and role of transgastric ultrasonography in the evaluation of the abdominal aorta and its branches and other abdominal structures. (ECHOCARDIOGRAPHY, Volume 8, May 1991)     

Low Body Mass Index Is Associated with a Positive Response during a Head‐Up Tilt Test

Background : To describe the association between body mass index (BMI) and a positive response during a head‐up tilt test (HUT) in patients referred for an investigation of syncope. Methods : Observational study of patients referred for the diagnostic evaluation of syncope. Patients were divided into four groups according to their BMI: <18.5 kg/m², 18.5–24.9 kg/m², 25–29.9 kg/m², and > 30 kg/m². Results : A total of 419 patients were evaluated. The mean age was 43 ± 22 years, and 62% were female. The prevalence of a positive tilt test was different between groups when stratified by BMI (P = 0.01), with a higher proportion of patients with positive tests among those with BMI <18.5 kg/m² compared with other groups (P = 0.05). Multivariate analysis also showed that underweight patients had a 3.9 times higher risk for a positive HUT response (P = 0.01); additionally, the use of contraceptive drugs was associated with a protective effect during HUT (odds ratio: 0.35, confidence interval:0.19–0.45, P = 0.001). Conclusion : In our sample, changes in BMI are associated with a positive response for HUT, and oral contraceptives seemed to protect against this response. Further studies are needed with larger numbers of patients to corroborate this finding. (PACE 2013; 36:37–41)