A new contrast parameter for visualization of the cross-link density in rubber based on the dipolar-correlation effect

A new parameter for NMR mapping is suggested on the basis of the mean squared dipolar fluctuation (MSDF). The MSDF characterizes the relaxation mechanism due to ultra-slow dipolar fluctuations in liquids subject to local anisotropy of molecular motions. These fluctuations can be monitored on the time scale exceeding a few microseconds. In rubber materials, the MSDF is a function of the density of chemical cross-links strongly affecting (anisotropic) mesh chain fluctuations. Experimentally, the MSDF is determined from the attenuation curves of the quotient of the amplitudes of the stimulated and the primary echoes produced by the three 90 degrees radio-frequency pulse sequence. In order to evaluate the MSDF maps, the latter sequence was combined with the standard scheme of the magnetic field gradients providing a spatial resolution. The pixel values of the MSDF are "visualized" using grey shades related to the equidistant intervals covering the whole range of the measured values. The MSDF maps are demonstrated for the two composite samples. The first sample consists of a water filled tube in the middle part surrounded by high molecular mass polyisoprene (PI) in the outer part. The relaxation weighted spin density image of this sample is dominated by a water signal with PI producing a much weaker intensity. The MSDF map, on the contrary, enhances the relative intensity of the outer, PI, part while scaling the middle, water, part down to the level of noise. The second sample consists of the four rubber pieces with different cross-link density. This sample thus models an inhomogeneous rubber object. The MSDF map produces clear contrast for the relevant regions. The advantages of employing this kind of NMR mapping for a characterization of materials are discussed.

Reliability and validity of the German version of the European Addiction Severity Index (EuropASI)

OBJECTIVE

This study provides data on the psychometric characteristics of the German version of the European Addiction Severity Index (EuropASI). The ASI is a frequently used clinical and research instrument that measures problem severity among people with substance dependence.

METHOD

The German ASI was used in a sample of 112 consecutively admitted male psychiatric inpatients seeking treatment for severe alcohol problems. The conceptual structure of the German ASI subscales was investigated by analyzing the intercorrelations of the severity ratings and composite scores. Internal consistency, interrater reliability and concurrent validity in terms of correlations with other assessment instruments were evaluated.

RESULTS

The German ASI subscales proved to be independent or moderately correlated (-0.17 < r < 0.34). Each correlation coefficient between corresponding severity ratings and composite scores was significant (p < .0005), ranging from r = 0.47 to r = 0.93. Reliability measures indicated moderate to good internal consistency (Cronbach's alpha: 0.69-0.92) and moderate to excellent interrater reliability (intraclass correlation coefficient: 0.62-0.99). Validity was supported by significantly higher ratings in the alcohol section in alcohol dependent patients compared to patients without dependence (t = 2.99, 108 df, p = .004). Significant correlations (p < .001) were found between the alcohol use section and the Michigan Alcoholism Screening Test (r = 0.34 composite score and r = 0.44 severity rating) and between psychiatric status and the Symptom Checklist-90-revised (r = 0.55/0.51), supporting concurrent validity.

CONCLUSIONS

The German version presented evidence of acceptable psychometric properties and its applicability in German-speaking countries could be confirmed.

A higher rate of hyperandrogenic disorders in female-to-male transsexuals

In an effort to elucidate the aetiology of female-to-male transsexualism (FM-TS) 12 out of an annual sample of 16 untreated female-to-male transsexuals (FMT), aged 19 years 7 months (19;7) to 44 years 8 months (44;8) [median age (M) 27;5] were assessed by means of sexual-medical questionnaires, physical and endocrinological examination. The control group consisted of 15 healthy women (CF), aged 19 years 2 months (19;2) to 36 years 1 month (36;1) (M 22;7) without gender identity disorder, who were not under hormonal medication (including contraceptives). Baseline levels of testosterone (T; ng/dl), androstenedione (A4; ng/dl), dehydroepiandrosterone sulfate (DHEAS; ng/ml), luteinizing hormone (LH; IU/l), follicle stimulating hormone (FSH; IU/l), and sex-hormone binding globuline (SHBG; microgram/dl) were measured. A standard single-dose ACTH stimulation test (250 micrograms ACTH IV; Synacthen) was performed with all subjects. Aldosterone (ALDO), corticosterone (B), deoxycorticosterone (DOC), progesterone (PROG), 17-hydroxyprogesterone (17OHP), 11-deoxycortisol (S), cortisol (F), cortisone (E), pregnenolone (PREG) and 17-hydroxypregnenolone (OHPREG) were assessed before and 60 min after ACTH stimulation. Transvaginal ultrasound was performed in nine out of 12 FMT (20;11 to 44;8, M 27;5; m 29.1 +/- 7.5) but not in CF. Results showed that 10 FMT (83.3%) and five CF (33.3%) were above normal values for at least one of the measured androgens. Baseline levels of T and A4 were significantly higher in FMT than in CF (T: 54.0 +/- 13.8 vs. 41.1 +/- 12.8; A4: 244.8 +/- 73.0 vs. 190.5 +/- 49.3; p < .05), whereas DHEAS, SHBG, LH and FSH did not differ between the groups. Unbound T (T/SHBG ratio) was higher in FMT (72.0 +/- 67.6) than in CF (26.4 +/- 15.1). Baseline levels of 17OHP, OHPREG and DOC were higher in FMT than in CF (p < .05). After ACTH stimulation 17OHP and OHPREG remained higher in FMT than in CF (p < .05). Single case analysis of ACTH stimulation test together with physical examination revealed symptoms for non-classical congenital adrenal hyperplasia (NC-CAH) in six FMT (50%) and two CF (13.3%). Eight out of nine FMT who were assessed by means of transvaginal ultrasound (i.e. 88.9%; 50.0% of 16) had polycystic ovaries (PCO). Oligomenorrhoea or menstrual dysregularities (81.7% of 16 FMT vs. 0% of CF), hirsutism (56.2% of 16 FMT vs. 13.3% of 15 CF) and adiposity (25.0% vs. 0%) were frequent in FMT, but not in CF. Hyperandrogenism with polycystic ovarian syndrome (PCOS) and adrenocortical hyperresponsiveness to ACTH seems to be a common finding in FMT. This offers support for a hormonal factor in the genesis of FM-TS. Because the prevalence of PCOS and NC-CAH in the female population is higher than FM-TS, the true nature of this factor and its interaction with environmental influences remains unknown.