Comparative analysis of more than 3000 sequences reveals the existence of two pseudoknots in area V4 of eukaryotic small subunit ribosomal RNA.

The secondary structure of V4, the largest variable area of eukaryotic small subunit ribosomal RNA, was re-examined by comparative analysis of 3253 nucleotide sequences distributed over the animal, plant and fungal kingdoms and a diverse set of protist taxa. An extensive search for compensating base pair substitutions and for base covariation revealed that in most eukaryotes the secondary structure of the area consists of 11 helices and includes two pseudoknots. In one of the pseudoknots, exchange of base pairs between the two stems seems to occur, and covariation analysis points to the presence of a base triple. The area also contains three potential insertion points where additional hairpins or branched structures are present in a number of taxa scattered throughout the eukaryotic domain.

The two-factorial symptom structure of post-traumatic stress disorder: depression-avoidance and arousal-anxiety.

UNLABELLED: The first part of this study showed that the DSM-III-R symptom structure of post-traumatic stress disorder (PTSD), i.e. criteria B (reexperience), C (avoidance-numbing), and D (arousal), and, consequently the diagnosis of PTSD, could not be validated in fire and car-accident victims. The aims of this study were to: (i) determine the factors as well as their structure in the symptoms of PTSD; and (ii) develop a new classification or typology of PTSD. Exploratory and confirmatory factor analyses and cluster analyses were employed to: (i) examine the factors in PTSD symptomatology; and (ii) find and validate adequate diagnostic criteria for PTSD. The Composite International Diagnostic Interview (CIDI), PTSD Module, was used between 7 and 9 months after the traumatic event in a study group of 185 victims of two different traumatic events, i.e. 130 fire and 55 car-accident victims. Our findings support the existence of two factors, i.e. a first labeled 'depression-avoidance (DAV) dimension', as it contains items reminiscent of depression and avoidance, and a second labeled 'the anxiety-arousal (AA) dimension', as it contains symptoms reminiscent of anxiety and increased arousal. Cluster analysis yielded two clusters, i.e. a cluster of subjects with PTSD cases and another with non-cases. Our PTSD algorithm was significantly less restrictive than the DSM-III-R diagnosis of PTSD. There are only quantitative, but no qualitative, differences between the cluster analytically derived classes. IN CONCLUSION: PTSD is not a well-delineated clinical entity, as there is a clinical continuum from PTSD non-cases to cases with less and more severe DAV and AA symptoms. It is more appropriate to express PTSD in terms of general severity of PTSD and severity of the DAV and AA dimensions.

Epidemiologic and phenomenological aspects of post-traumatic stress disorder: DSM-III-R diagnosis and diagnostic criteria not validated.

The aim of this cohort study was: (i) to validate the diagnostic criteria for post-traumatic stress disorder (PTSD) of the DSM-III-R; and (ii) to examine the incidence rate of PTSD in a study population exposed to two different traumatic events, i.e. a fire in a hotel ball-room and a multiple collision car-crash on a Belgian highway. One hundred and eighty-five victims (130 fire and 55 car accident victims) were assessed between 7 and 9 months after the traumatic event using the Composite International Diagnostic Interview (CIDI), PTSD Module, a fully structured diagnostic interview for the assessment of PTSD according to DSM-III-R criteria. Twenty-three percent of the study population met DSM-III-R criteria for PTSD. By means of unsupervised and supervised multivariate statistical analyses we were unable to validate the three-factorial structure, i.e. criteria B, C and D, of the DSM-III-R PTSD diagnosis. The latter relies heavily on the C diagnostic criteria, which appear to be too restrictive. Women were more likely to develop symptoms of reexperience (B) and arousal (D) than men. There was a significantly higher incidence of criteria B, C and D, but not of PTSD, in fire than in car-accident victims. Between 42 and 57% of the victims developed the first PTSD symptoms on the day of the trauma; within the next week these incidence rates increased to 77.1, 57.8 and 73.5% for criteria B, C and D, respectively. In conclusion, this study was unable to demonstrate the validity of the diagnostic criteria for PTSD according to DSM-III-R. The present cohort study has defined a number of factors that may predict new occurrences of PTSD symptoms after a traumatic event, i.e. gender, type of trauma and time delay between the trauma and the assessment of the diagnostic criteria.

Active anterior rhinomanometry in pre- and postoperative evaluation, use of Broms' mathematical model.

The authors studied the value of the Broms' mathematical model for active anterior rhinomanometry in a pathological population. They compared all different variables of a pathological group with a normal group and found significant differences for v0, v2 and R. There existed no difference between the means of v0 before and after surgery. There existed, however, a strongly positive correlation between the expiration and inspiration value. The influence of surgery was always significant for the variables v1, v2, v3 and R. Furthermore, the absolute deviation between the computed values and the recorded values tended to be very small. So, the authors concluded that rhinomanometry is a valuable aid in judging pre- and postoperative results.

Dimensions of first year university student behavior.

Eight hundred and seventy-four freshmen underwent a structured interview to search for characteristics in student behavior. The scores were analysed using agglomerative and divisive hierarchical clustering methods. The results demonstrate the presence of two opposite dimensions in freshman behavior: the first referred to study involvement, the second referred to campus participation.

LMSMVE: a program for least median of squares regression and robust distances.

The program LMSMVE performs robust regression analysis by using the method of the least median of squares. It also computes robust distances to locate leverage points, that is, outliers with respect to the set of independent variables. LMSMVE constructs plots of least median of squares residuals against robust distances. Both methods can tolerate up to half the data being outliers before they fail to give results that describe the bulk of the data. A complete system that operates directly on SYSTAT files is available for the IBM PC and compatibles; it includes a utility that converts ASCII files to SYSTAT format.

Hierarchical cluster analysis of emotional concerns and personality characteristics in a freshman population.

An investigation was conducted to examine correlates of emotional concerns and personality characteristics in a general freshman population. The scores were analysed using agglomerative and divisive hierarchical clustering methods. The results indicate the presence of a coherent group which concerns emotional factors, and show a distinct user group strongly related to the first group. The data do not determine the importance of various personality factors in influencing emotional concerns.

Search for the relationship between interrupted university attendance of first year students and some psychosocial factors.

Eight hundred and seventy-four freshmen underwent a structured interview to study the relationship of some psychosocial factors to interrupted university attendance. The scores were measured using the SPSS computer package. The scores indicate negative significant relationships between interrupted university attendance and satisfactory housing, own study choice, study motivation, campus participation and irregular alcohol consumption. The results demonstrate a positive significant relationship between withdrawal and the distance from the university.

Visco-elastic properties of four currently used tissue conditioners.

About 60% of complete denture wearers experience a mostly painless inflammation of the palatal mucosal membrane. Especially prosthetic trauma and Candida albicans infection are assumed as aetiological factors. The treatment can be prosthetic or medicamentous, dependent on the cause. In this connection tissue conditioners could be very effective by their visco-elastic properties. Four tissue conditioners have been examined (Coe Comfort, FITT, Ivoseal, Visco Gel) for their impression softness and elastic recovery. All tests have been done on 20 mm specimens. The length of the specimens was measured during a 10 min compression and a 60 min relaxation. Eight ageing times have been taken into consideration. From the results large differences appear between the various tissue conditioners. Two main groups can be distinguished. FITT and Ivoseal are harder materials, whereas Coe Comfort and Visco Gel are softer. The ageing time has a clear hardening influence especially on Visco Gel. Visco Gel appears to be the best tissue conditioner by its relative plasticity during the first hours and its elastic behaviour during a longer ageing period. The clinical relevance of these materials is certainly not proved by this study. Further research will show this.

On the calculation of a robust S-estimator of a covariance matrix.

An S-estimator of multivariate location and scale minimizes the determinant of the covariance matrix, subject to a constraint on the magnitudes of the corresponding Mahalanobis distances. The relationship between S-estimators and w-estimators of multivariate location and scale can be used to calculate robust estimates of covariance matrices. Elemental subsets of observations are generated to derive initial estimates of means and covariances, and the w-estimator equations are then iterated until convergence to obtain the S-estimates. An example shows that converging to a (local) minimum from the initial estimates from the elemental subsets is an effective way of determining the overall minimum. None of the estimates gained from the elemental samples is close to the final solution.

Search for the relationship between academic performance and some psychosocial factors. The use of a structured interview.

Eight hundred and seventy-four freshmen underwent a structured interview to study the relationship of psychosocial factors to academic performance. The scores were measured using the SPSS computer package. The results demonstrate positive significant relationships between study success and sex, fulfilled study expectations, fulfilled college expectations, informal contacts with faculty members, introversion and confidence. The scores indicate negative significant relationships between study success and regular alcohol drinking, abuse of medication and some psychopathological symptoms.

[The effect of swimming on the nasal passages and on tube function in children]. / De invloed van het zwemmen op de neusdoorgankelijkheid en de tubafunktie bij kinderen.

In two studies the authors want to confirm experimentally what is assumed in every day ENT-practice: otitis and sinusitis are not infrequent complications of swimming. The first study, involving 60 children with chronic non-specific lung diseases shows that swimming in a sea water pool increases the nasal airway resistance during two days. In the second study, performed in 32 normal children swimming in a chlorous pool, a negative relationship is found between the number of days after the swimming and the increased nasal airway resistance. Probably other factors also play a part in this phenomenon. Due to the too small number of children showing an otitis media with effusion, the influence of swimming on the function of the Eustachian tube could not be determined.