Changes in transglutaminase activity in an experimental model of pulmonary fibrosis induced by paraquat.

An experimental model of pulmonary fibrosis has been developed by dosing rats with one-fifth the LD50 dose of the herbicide paraquat on 5 consecutive days. Approximately 50% of the rats died within 4 days of the completion of dosing, showing macroscopic changes and wet weight increases in the lung consistent with severe oedema. Those animals which died between Days 4 and 10 had markedly increased levels of hydroxyproline in the lung, maximum at Day 6, and increased prolyl hydroxylase activity, maximum at Day 4. These changes, together with an increase in thymidine incorporation into DNA, and increased lung DNA content, were consistent with the development of fibrosis. Measurement of transglutaminase activity in the lung showed marked increases at Days 4 and 10 after completion of dosing. This activity paralleled closely the changes in prolyl hydroxylase activity and became increasingly associated with particulate protein present in the "nuclear pellet" fraction. The presence of zymogen plasma transglutaminase trapped in lung homogenates could not be demonstrated but the contribution by the active plasma transglutaminase (Factor XIIIa) to increases shown at Day 4 cannot be ruled out.     

A method for sampling the stages of amelogenesis on mandibular rat incisors using the molars as a reference for dissection

A method for locating specific stages of amelogenesis on continuously erupting incisors was devised for rats weighing 101 +/- 5 g (n = 32). The technique is based on reflecting reference lines from the mandibular molars as perpendiculars to the labial surface of mandibular incisors. From these reference lines additional measurements are then made along the midline of the labial surface of the incisor in an apical or incisal direction to find the site desired for sampling. Histological studies on 24 decalcified incisors split into segments by using such reference lines and reconstructed by morphometry indicated that a reference line reflected from the contact point between the 2nd and 3rd molars crossed the enamel organ and adjacent enamel at 3,181 +/- 329 microns incisal to the start of the secretory zone of amelogenesis. A reference line from the 2nd and 1st molars crossed the enamel organ and enamel at 1,238 +/- 424 microns incisal to the start of the maturation zone of amelogenesis, while a reference line from the mesial side of the 1st molar crossed the enamel organ and enamel almost exactly where the enamel becomes completely soluble following prolonged decalcification in EDTA. Although reference lines were reproducible within a group of male rats having similar body weights, the linear distance between the apical end of the incisor and the point at which they crossed the tooth increased at a rate of 1 mm per 159 g for rats between 50 and 300 g body weight. This suggests that molars do not maintain a fixed relationship to incisors over time, and extreme care must be taken to standardize an experiment to a specific body weight when using this method.     

Evaluation of a commercial latex agglutination test for detecting antibodies to cytomegalovirus in organ donors and transplant recipients

A commercial latex agglutination test was evaluated for use in detecting CMV antibody in organ donors and transplant recipients. When compared with indirect and competitive enzyme-linked immunosorbent assays (ELISAs) and complement fixation tests (CFT), the test gave concordant results with 96.6% of sera. The latex agglutination test was more sensitive than CFT but less sensitive than ELISA. The major advantage of the latex agglutination test was its simplicity and rapidity. Taking only 8 min to perform, it is very suitable for testing sera from organ donors, since the time available for such tests is short because of the finite ischaemic time, particularly for liver and heart transplantation.     

Effect of inapparent murine hepatitis virus infections on macrophages and host resistance

Inapparent infections of mice with murine hepatitis virus (MHV) altered host resistance to experimental infection with a second virus, encephalomyocarditis virus (EMC), reduced the protective effects of exogenously administered interferon against EMC infections, and it altered macrophage ectoenzyme phenotypes in two macrophage populations. Resident peritoneal macrophages from mice experimentally infected with one of two strains of MHV also demonstrated altered ectoenzyme phenotypes. These data demonstrate that inapparent infections with MHV alter several host resistance and macrophage parameters and directly demonstrate that effects of inapparent MHV infection on macrophage parameters can be reproduced experimentally.     

Gm allotypes in IgA deficiency

Gm phenotypes were examined in 90 Swedish IgA-deficient (less than 0.05 g/litre of serum IgA) donors and 40 normal first and second degree relatives of six of these donors. The G1m1,2, G3m5 and Km1 frequency in the group of IgA-deficient donors did not differ from that found in the normal population. Among the relatives, HLA and/or Gm identical normal sibs were observed. Anti-IgA antibodies were present in 29 of the IgA-deficient donors and anti-IgG in seven. No association between the two was found. A statistically significant association between the G1m-2 phenotype and the presence of anti-IgA antibodies was observed. When subdivided according to HLA type, a non-random distribution of Gm phenotypes was seen in HLA-B8/DR3 positive individuals with anti-IgA antibodies (HLA-B8/DR3 being the haplotype associated with IgA deficiency). These data suggest an association between IgA deficiency, anti-IgA and the studied Gm allotypes.     

In vitro susceptibility of Pseudomonas species to carbenicillin and trimethoprim-sulfamethoxazole.

We compared susceptibility tests of 47 Pseudomonas aeruginosa isolates and 40 Pseudomonas species to carbenicillin and trimethoprim-sulfamethoxazole by the MS-2 and Sceptor systems and agar dilution. The major and very major errors encountered in these tests in the MS-2 and Sceptor systems raise doubts about the accuracy of these methods for testing P. aeruginosa and confirm that they should not be used for testing the susceptibility of Pseudomonas species to the two drugs tested.     

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.