Population study of T cell receptor V beta gene usage in peripheral blood lymphocytes: differences in ethnic groups.

The T cell receptor (TCR) V beta repertoire in peripheral blood lymphocytes (PBL) of a large number of healthy individuals was analysed by quantifying V beta-specific mRNA using the method of anchored multiprimer DNA amplification and a reverse dot blot assay. Among 16 V beta gene families examined, particular V beta genes were noted to be unequally expressed in the PBL of 70 healthy donors. The frequently used genes belong to the V beta 4, 5, 6, 8 and 13 (12) families, while V beta 1, 9 and 15 were the least frequently used gene families. This bias in gene usage was observed in all individuals. Marked deviation from the mean percentage usage was noted for some V beta genes in individuals when their PBL were examined serially, but the common pattern of biased usage was not grossly distorted. When the TCR repertoire of different ethnic groups was examined, a lower mean frequency of V beta 3.2 was seen in the repertoire of 19 Caucasians compared with 25 age-matched Samoans (P < 0.003). Conversely, the expression of V beta 5.1 and V beta 5.3 was higher in Caucasians than in 51 age-matched Polynesians (Maoris and Samoans, P < 0.003). Considering the 20% co-efficient of variation in the estimate of V beta gene usage, our data from 70 unrelated individuals suggest that in PBL, individual variations in the TCR repertoire were superimposed upon a common biased usage of V beta genes in the general population.     

Problem behavior in boys with fragile X syndrome

This study examines problem behavior over time in 59 boys with fragile X syndrome (FXS), aged 4-12 years, using the Child Behavior Checklist (CBCL). Approximately 49% of the boys scored within the borderline or clinical range on total problem behavior, while 56-57% scored in the borderline or clinical range on the attention and thought problems subscales, and 26% scored in this range on the social problems subscale. With a mean of 2.5 assessments per child, behavior problems were stable during the 3-year period of study. Total problem behavior was higher for children who displayed autistic behavior, were rated as low in adaptability, had mothers with higher maternal education levels, and were on medication. Mothers with more education also rated their children as having more attention, thought, and total problems. Children taking medication differed from boys who were not taking medication on social problems, but not on attention and thought problems. Low adaptability and more autistic characteristics predicted thought problems.     

Phenotypic markers associated with gastrointestinal Aeromonas hydrophila isolates from symptomatic children.

Aeromonas hydrophila gastroenteritis was detected in 12 pediatric patients during a 5-month period. Chief complaints included bloody diarrhea, fever, vomiting, and abdominal pain. Severe symptoms in two patients necessitated hospitalization and supportive care. Phenotypic characteristics associated with enterotoxigenicity of A. hydrophila strains demonstrated that all 12 isolates were cytotoxic to HeLa cells and most were lysine decarboxylase positive (75%). A correlation existed between the presence of the five virulence-associated markers of two isolates of A. hydrophila and the severity of disease. Although the length and symptoms of gastroenteritis varied among all 12 patients, most had self-limiting diarrhea. The frequent occurrence of A. hydrophila gastroenteritis in pediatric patients warrants a greater appreciation of this agent as a significant cause of diarrhea, especially in summer.     

Homologues of insecticidal toxin complex genes in Yersinia enterocolitica biotype 1A and their contribution to virulence

Yersinia enterocolitica is an enteric pathogen that consists of six biotypes: 1A, 1B, 2, 3, 4, and 5. Strains of the latter five biotypes can carry a virulence plasmid, known as pYV, and several well-characterized chromosomally encoded virulence determinants. Y. enterocolitica strains of biotype 1A lack the virulence-associated markers of pYV-bearing strains and were once considered to be avirulent. There is growing epidemiological, clinical, and experimental evidence, however, to suggest that some biotype 1A strains are virulent and can cause gastrointestinal disease. To identify potential virulence genes of pathogenic strains of Y. enterocolitica biotype 1A, we used genomic subtractive hybridization to determine genetic differences between two biotype 1A strains: an environmental isolate, Y. enterocolitica IP2222, and a clinical isolate, Y. enterocolitica T83. Among the Y. enterocolitica T83-specific genes we identified were three, tcbA, tcaC, and tccC, that showed homology to the insecticidal toxin complex (TC) genes first discovered in Photorhabdus luminescens. The Y. enterocolitica T83 TC gene homologues were expressed by Y. enterocolitica T83 and were significantly more prevalent among clinical biotype 1A strains than other Yersinia isolates. Inactivation of the TC genes in Y. enterocolitica T83 resulted in mutants which were attenuated in the ability to colonize the gastrointestinal tracts of perorally infected mice. These results indicate that products of the TC gene complex contribute to the virulence of some strains of Y. enterocolitica biotype 1A, possibly by facilitating their persistence in vivo.     

Comparison of relative uses of commercial assays for Toxoplasma gondii IgM antibodies.

AIMS: To compare the sensitivity and user friendliness of seven commercially available enzyme linked immunoabsorbent assay (ELISA) kits for toxoplasma specific IgM. METHODS: Five antibody capture assays supplied by Abbott, Mercia, Northumbria, Organon and Sorin, and two indirect ELISA assays from Biostat and Mast, were assessed. Using defined dilutions of Toxoplasma gondii specific IgM, the performance and sensitivity of each assay was established. They were further assessed on a panel of 27 sera with a range of dye test and IgM results (as determined by the Scottish Toxoplasma Reference Laboratory). All of the assays were performed by three experienced operators and assessed for user satisfaction. RESULTS: The Mast, Organon, and Abbott assays were of low sensitivity; the Mercia and Northumbria were of high sensitivity; and the Biostat and Sorin assays produced too many false positive results. The Mercia kit provided most user satisfaction; the Mast and Abbott assays were most difficult to use. CONCLUSIONS: Local laboratories investigating toxoplasma infection should have three tests: one IgG and two IgM (high and low sensitivity) to help in the timing of infection. Alternatively, one sensitive IgM assay, such as that of Mercia, could be used by selecting appropriate high and low thresholds.     

Repertoire of transcribed peripheral blood T-cell receptor beta chain variable-region genes in acute rheumatic fever.

Patients with severe group A streptococcal infections have abnormalities in the Vbeta repertoire of peripheral blood T cells that are consistent with superantigen stimulation by cytoplasmic membrane proteins. The purpose of this study was to determine whether similar changes in Vbeta repertoire could be found for patients with acute rheumatic fever (ARF). The mean Vbeta repertoire of peripheral blood T cells in nine hospitalized ARF patients was similar to that of 34 controls and did not change during 6 months of follow-up in 6 of the ARF subjects. We were unable to detect changes in the Vbeta repertoire of peripheral blood T cells from patients with ARF that could be attributed to the influence of a superantigen.     

The degradation of serum amyloid A protein by activated polymorphonuclear leucocytes: participation of granulocytic elastase

To determine the role of inflammation in amyloidogenesis, we have studied the degradation of human serum amyloid A (SAA) protein by purified preparations of human blood polymorphonuclear leucocytes (PMN) and monocytes. When both PMN and monocytes were incubated in SAA-containing medium, the concentration of SAA as measured by a competitive anti-AA radioimmunoassay decreased over time. The rate of decrease of SAA was similar for both monocytes and PMN and there were no differences between four patients with amyloidosis and three normal controls. Resting PMN from normal volunteers were able to degrade SAA to smaller acid-soluble peptides within 16 hr while zymosan-activated PMN produced significant degradation within 1 hr (31%–50%). The supernatants from zymosan-treated PMN also caused marked SAA degradation within 1 hr.

The following enzyme inhibitors were able to prevent degradation of SAA by PMN supernatants; phenylmethylsulphonyl fluoride, a serine esterase inhibitor; α₁ anti-trypsin and soybean trypsin inhibitor; and acetyl-ala-ala-pro-val-chloromethyl ketone, an elastase inhibitor. The ability of a neutral lysosomal enzyme to degrade SAA was further confirmed by showing that purified PMN elastase significantly degraded ¹²⁵I-SAA.

We conclude that PMN contain one or more lysosomal enzymes capable of degrading SAA, an apoprotein of HDL₃ serum lipoproteins. Alteration in SAA proteolysis by activated PMN may contribute to the deposition of amyloid fibrils in the tissues of patients with chronic inflammatory disease.

     

Resting whole blood viscosity of elite rowers is related to performance

This study investigated the relationships between resting whole blood viscosity (WBV), haemoglobin concentration (HGB), haematocrit (HCT), and performance in 25 highly-trained national squad rowers (11 women and 14 men). The WBV and HGB were measured at rest prior to a 2500 m simulated race on a Concept rowing ergometer when performance (P) was measured by average velocity. A group of 12 rowers were measured on just one occasion, another 11 were measured twice with an intervening 5 weeks of continued training and 2 were measured three times, the third test after another 4 weeks. Regression analyses making simultaneous use of both intra- and interindividual data indicated a significant inverse relationship between P and WBV (at both high and low shear rates), a relationship which was strengthened after statistically controlling for the effects of HGB, this effect being slightly more significant than HCT. A significant positive regression also emerged between P and HGB, but only after statistically controlling for the influence of WBV at high shear rate. Overall, stronger relationships were demonstrated in the male rowers compared with the female. These data, in the light of previous evidence that fitter people tend to have lower WBV, would indicate that blood rheology unrelated to HGB (or HCT) is related to performance in relatively homogeneous and already highly-trained athletes.     

Effect of articular disease and total knee arthroplasty on knee joint-position sense

Joint proprioception in the human knee has been studied using two previously described tests. Threshold of detection of slow, constant, passive motion and ability to reproduce angles to which the knee was passively placed were accurately measured. A group of postoperative total knee arthroplasty (TKA) patients were examined. All patients also had documented articular disease in the unoperated knee. Results were compared to age-matched controls. In addition, a young control group was studied for comparison to both groups. A significant difference was seen between the young control group and the older control group in both tests performed. Age-matched controls and the postoperative patients demonstrated an even greater difference. There was, however, no difference between the operated and unoperated knee among the TKA patients. It is concluded that joint proprioception declines to some degree with normal aging. A more marked decline is associated with degenerative joint disease. Total joint replacement, however, did not lead to a further decrease in sensation.     

Cardiovascular indices of physiological arousal in boys with fragile X syndrome

In this study, the relationship between physiological arousal, as indexed by heart rate variability, was examined in boys with fragile X syndrome (FXS) and typically developing boys matched on chronological age. In addition, the relationship of heart activity to clinical and molecular factors in the group of boys with FXS was examined. Results suggest that boys with FXS have higher levels of heart activity during the passive phases, as reflected in shorter heart periods. This high level of heart activity appears to be due to increased sympathetic activity and reduced parasympathetic activity. Boys with FXS did not display the expected patterns of heart activity in response to phases of increasing challenge, and sympathetic and parasympathetic systems did not appear coordinated in these boys with FXS. Clinical factors may be related to neural regulation of heart activity while molecular factors do not appear to be.