Dielectric properties of low-water-content tissues

The dielectric properties of two low-water-content tissues, bone marrow and adipose tissue, were measured from 1 kHz to 1 GHz. From 1 kHz to 13 MHz, the measurements were performed using a parallel-plate capacitor method. From 10 MHz to 1 GHz, a reflection coefficient technique using an open-ended coaxial transmission line was employed. The tissue water contents ranged from 1 to almost 70% by weight. The dielectric properties correlate well with the values predicted by mixture theory. Comparison with previous results from high-water-content tissues suggests that bone marrow and adipose tissues contain less motionally altered water per unit dry volume than do the previously studied tissues with lower lipid fractions. The high degree of structural heterogeneity of these tissues was reflected in the large scatter of the data, a source of uncertainty that should be considered in practical applications of the present data.     

Psychiatrists' models of mental illness and their personal backgrounds.

Seventy-nine junior psychiatrists at the Maudsley Hospital answered 16 biographical questions and a 68-item questionnaire measuring attitudes to the psychoanalytical, biological, social, behavioural, and anti-medical models of mental illness. The psychoanalytical model was the most clearly defined and its adherents the most dogmatic, while those supporting the social model were the most eclectic. Sex, social class, education and political sympathy proved a poor guide to the orientation of the respondent. Individuals who had decided on a career in psychiatry before entering medical school were the most critical of the biological model. Biologically minded psychiatrists were older and, in contrast to Kreitman's findings, there was a shift from a psychoanalytical to a biological preference with increasing psychiatric experience. The importance of scientific attitudes in psychiatry was endorsed by biologically and behaviourally inclined psychiatrists but denigrated by supporters of the analytical approach. Adherents of the psychoanalytical model had as many academic qualifications as the biologically inclined, but had fewer publications and were less active in research. It appears that interest in psychoanalysis is antipathetic to the development of scientific attitudes conducive to research.     

Polyvalent pneumococcal-polysaccharide immunization of patients with sickle-cell anemia and patients with splenectomy.

To reduce the risk of infection from Streptococcus pneumoniae in hyposplenic patients we administered octavalent pneumococcal vaccine to 77 patients with sickle-cell disease and 19 asplenic persons and compared their response with 82 controls (38 age-matched normal persons and 44 normal black African children). Fifty micrograms each of pneumococcal-polysaccharide Types 1, 3, 6, 7, 14, 18, 19, and 23 were administered subcutaneously. Post-immunization serums (three to four weeks) were available from 52 of 77 patients with sickle-cell disease; the percent responding and the magnitude of the indirect hemagglutination response were comparable to those of the controls. Within two years after immunization we observed eight Str. pneumoniae infections in 106 age-matched unimmunized patients with sickle-cell disease, but none in the 77 immunized (P less than 0.025). We conclude that pneumococcal polysaccharides are immunogenic in hyposplenic patients and may protect against systemic Str. pneumoniae infection.     

Borderline personality disorder characteristics in young adults with recurrent mood disorders: a comparison of bipolar and unipolar depression

BACKGROUND: In young adults it can be difficult to differentiate between an early bipolar illness and borderline personality disorder. There are considerable areas of clinical overlap between cyclothymic temperament, bipolar-spectrum disorders and borderline characteristics. The aim of this study was to measure borderline characteristics in young adults during an index depressive episode and to compare three diagnostic groups: DSM-IV bipolar affective disorder (BPAD); bipolar spectrum disorder (BSD); and DSM-IV recurrent major depressive disorder (MDD). METHODS: Eighty-seven young adults with a current episode of major depression and at least one previous episode of depression were recruited from consecutive referrals to a psychiatric clinic. Diagnoses were based on the Structured Clinical Interview for DSM-IV (SCID-1) and recently proposed structured diagnostic criteria for BSD. All patients also completed the borderline questions from the screening questionnaire of the International Personality Disorders Examination (IPDE). RESULTS: Diagnostically, the cohort of 87 patients divided into three groups: 14 with BPAD; 27 with BSD; and 46 with MDD. None of the subjects fulfilled DSM-IV or ICD-10 diagnostic criteria for personality disorder and all three groups were well matched in terms of age, gender distribution, ethnicity, socioeconomic and educational status, age at onset of illness, and severity of index depressive episode. Both of the bipolar-depressed groups reported significantly higher median levels of borderline characteristics than the MDD group (p<0.0001). Three of the borderline characteristics emerged as potentially useful in differentiating bipolar depression from unipolar depression: 'I've never threatened suicide or injured myself on purpose' (sensitivity=0.93; positive predictive value [PPV]=56.7); 'I have tantrums or angry outbursts' (sensitivity 0.66; PPV=65.6%); and 'Giving in to some of my urges gets me into trouble' (sensitivity=0.76; PPV=59.6%). LIMITATIONS: All of the subjects were recruited from a university health service clinic and as such are unlikely to be representative of patients from more diverse socio-economic backgrounds. No structured diagnostic assessment of personality disorder was administered. The diagnostic criteria for BSD are not yet fully validated. CONCLUSIONS: Young adults with bipolar depression exhibit significantly higher levels of borderline personality pathology than those with unipolar depression. Those borderline screening questions that reflect cyclothymic characteristics or depressive mixed states may be of practical use to clinicians in helping to differentiate between bipolar depression and unipolar depression in young adults.     

Evaluation of a fluorescence-based PCR method for identification of serogroup a meningococci

Standard and fluorescence-based PCR assays were developed for the identification of serogroup A meningococci by detection of the mynA gene. This assay was evaluated using bacterial cultures but provides the sensitivity required for the detection of the mynA gene from bodily fluids during meningococcal disease.     

Recurrent wavefront morphologies: A method for quantifying the complexity of epicardial activation patterns

We have developed a method for quantifying the complexity of activation patterns observed during ventricular fibrillation (VF) that is based on our previously reported methodology for decomposing epicardial mapping data into a set of isolated wavefronts. One-half second datasets are acquired from a 21×24 array of unipolar electrodes (1 mm spacing), and the wavefronts are isolated. A correlation technique is used to compute the similarity between all possible pairs of the isolated wavefronts. From these data, the wavefronts are sorted into clusters, each of which represents a recurring wavefront morphology. We define multiplicity (M) as the number of clusters needed to account for 90% of the total activations in the VF episode.M measures the complexity of the rhythm. In repetitive patterns (e.g., sinus rhythm),M=1, indicating that the same morphology repeatedly activates the mapped region. Typically, in VF,M>1, with larger numbers representing more complex, disorganized patterns. As an example, we computedM at 5, 10, 15, and 20 sec after electrical induction of VF in six pigs.M decreased significantly (p<0.001), suggesting increasing organization during this period.     

Human mini-chromosomes in mouse embryonal stem cells

We have introduced human mini-chromosomes of 4 Mb and approximately 15 Mb in size into mouse embryonal stem cells. Although these human mini- chromosomes are stable in hamster and chicken cells, they re-arrange or segregate aberrantly in the embryonal stem cells and are rapidly lost in the absence of selection. However, one of the mini-chromosomes re- arranged, acquired mouse centromeric sequences and was then stably maintained for at least 60 population doublings in culture. This mini- chromosome, which is 4 Mb in size, is a candidate for a mouse germ line chromosome vector.