On capillary electrophoresis of the chemically pure thioxo peptide Ala-Phe-psi[CS-N]-Pro-Phe-4-nitroanilide a peak splitting was observed at a capillary temperature of 25 degrees C. By contrast, the oxo peptide analogue exhibits a single, sharp peak under these conditions. Both peaks of the thioxo compound coincided gradually when the temperature was increased to 60 degrees C. Peak fusion was reverted by cooling down the heated sample. This behavior could be attributed to the electrophoresis-mediated separation of the cis/trans prolyl bond isomers of the thioxo peptide, allowing data of this conformational equilibrium to be determined. Derived from computational data about molecular volume and the hydration energy of low-energy cis and trans isomeric structures, the more rapid migration of the cis form in comparison to trans may be explained by structural parameters.

Algorithms↗

PubMedDate not supplied

Micrometastases in carcinoma of the upper aerodigestive tract: detection, risk of metastasizing, and prognostic value of depth of invasion.

BACKGROUND: The purpose of this study was to investigate the incidence of micrometastases from squamous cell carcinomas of the upper aerodigestive tract in neck dissection specimens, and to determine whether features of the primary tumor might be of prognostic value for metastasizing. METHODS: Seventy-six originally pNO staged neck dissection specimens from 60 patients were evaluated using serial sectioning in 10-micrometer intervals, H&E staining and immunostaining with an antibody to pan-cytokeratin. The influence of the variables pT-category, cytologic grade, and maximum depth of invasion of the primary tumor on the nodal status was analyzed in 128 patients. RESULTS: The examination of 1020 lymph nodes from 76 neck dissection specimens revealed 8 micrometastases in 6 specimens (7.9%) from 6 patients with oral and pharyngeal primaries, resulting in upstaging. Six micrometastases were located in lymph nodes of 3-6 mm in diameter. Depth of invasion was the only significant risk factor for metastasizing selected in logistic regression. CONCLUSION: The surgeon should be aware of a relatively high incidence of micrometastases from oral and pharyngeal carcinomas, which are neither detectable preoperatively nor histopathologically by a reasonable effort. The measurement of the maximum depth of invasion of the primary can delineate a group of patients who should be treated by elective neck dissection.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Surgical therapy of a coronary artery fistula draining into the left atrium.

Coronary artery fistulas (CAFs) are rare vascular anomalies. We describe a case of CAF draining into the left atrium, combined with an atrial septum defect (ASD) and azygos continuity in a 3-year-old girl. Surgical therapy included closure of the ASD combined with closure of the CAF through a left atrial approach. Even though CAF can be treated by interventional means, surgical correction may be required in the presence of associated cardiac abnormalities.

Atrial Appendage↗

PubMedDate not supplied

The tridimensional personality model: influencing variables in a sample of detoxified alcohol dependents. European Fluvoxamine in Alcoholism Study Group.

C.R. Cloninger proposed a biosocial model for personality, linking personality traits to patterns of responses to various external stimuli, including alcohol. The Tridimensional Personality Questionnaire (TPQ) was administered in a multicenter study to detoxified alcohol-dependent patients (N = 521). The objectives of the study were to evaluate (1) the expression of the three personality dimensions, novelty-seeking (NS), harm avoidance (HA), and reward dependence (RD), of the TPQ in this sample, and (2) the influence of different variables on these personality dimensions. The following variables were selected for a multiple and a stepwise regression analysis: sex, family history for major psychiatric disorders, marital status, occupation, age at study enrollment, age of onset of alcoholism, serum cholesterol level, intake of neuroleptics or benzodiazepines for detoxification, and severity of depression and anxiety. In comparison to Austrian normative data, both sexes of detoxified alcohol addicts scored higher in HA. The variables examined explain 23% of the variance of NS and 35% of HA. Only one variable, namely age of onset, is significantly influencing NS (19% explained variance). HA is significantly influenced by three variables: anxiety state, anxiety trait, and sex (32% explained variance). RD is not influenced by any of the variables examined.

Adult↗

PubMedDate not supplied

Catalysis of protein folding by prolyl isomerase.

Rates of protein folding reactions vary considerably. Some denatured proteins regain the native conformation within milliseconds or seconds, whereas others refold very slowly in the time range of minutes or hours. Varying folding rates are observed not only for different proteins, but can also be detected for single polypeptide species. This originates from the co-existence of fast- and slow-folding forms of the unfolded protein, which regain the native state with different rates. The proline hypothesis provides a plausible explanation for this heterogeneity. It assumes that the slow-folding molecules possess non-native isomers of peptide bonds between proline and another residue, and that crucial steps in the refolding of the slow-folding molecules are limited in rate by the slow reisomerization of such incorrect proline peptide bonds. Recently the enzyme peptidyl-prolyl cis-trans isomerase (PPIase) was discovered and purified from pig kidney. It catalyses efficiently the cis in equilibrium trans isomerization of proline imidic peptide bonds in oligopeptides. Here we show that it also catalyses slow steps in the refolding of a number of proteins of which fast- and slow-folding species have been observed and where it was suggested that proline isomerization was involved in slow refolding. The efficiency of catalysis depends on the accessibility for the isomerase of the particular proline peptide bonds in the refolding protein chain.

Amino Acid Isomerases↗