Experience with prenatal fragile X detection

We have attempted the prenatal detection of the fra(X) 9 times. Three fra(X) positive fetuses have been diagnosed: 2 males and one female. The diagnosis on the 2 males has been confirmed. The testes of the 2 fra(X) positive fetuses appeared large for gestational age. However, results of anthropometric, bone age, anatomical and neurohistological studies were normal. Normal outcome was confirmed after birth in 2 males and one female on the basis of whole blood fra(X) studies. A presumptively positive female and a presumptively negative female await confirmation. Two presumptively negative males remain unborn. Further experience is needed to establish the reliability of the prenatal detection of fra(X) (q27).     

Methylation alterations of the MyoD1 upstream region are predictive of subclassification of human rhabdomyosarcomas.

MyoD1 expression is a distinguishing characteristic of rhabdomyosarcoma. In this study, distinct methylation alterations were identified in the 5'' flanking region of the MyoD1 gene from the two major subtypes, ie, alveolar and embryonal rhabdomyosarcoma. The MyoD1 methylation patterns of 26 rhabdomyosarcomas were compared with that of normal skeletal muscle and nonmuscle specimens by Southern blot analysis using methylation-sensitive restriction enzymes HhaI and HpaII. A 5-kb region immediately upstream of the MyoD1 coding sequence was found to be methylated in adult muscle and all nonmuscle tissues tested. The MyoD1 upstream region was unmethylated in the majority of the alveolar rhabdomyosarcomas (13 of 15, 87%) examined in this study. In contrast, 10 of 11 (91%) embryonal rhabdomyosarcomas showed a methylation pattern that was also observed in fetal muscle cells, in which the CpG sites in the MyoD1 upstream region were partially methylated. Our data suggest that the methylation status of the MyoD1 upstream CpG sites may be related to rhabdomyosarcoma tumorigenesis and may have valuable implications for its differential diagnosis.     

Reflex responses induced by tooth unloading

The reflex response of the masseter muscle to the rapid unloading of a single maxillary incisor tooth was studied. Unloading of a static force of 2 N in the horizontal direction resulted in a short-latency excitation, inhibition, and long-latency excitation of masseter muscle activity occurring at latencies of approximately 13, 20, and 40 ms, respectively, with a corresponding change in bite force occurring slightly later in each case. Following the blocking of periodontal input by the injection of local anesthetic around the stimulated tooth, inhibitory responses were abolished. Therefore, it is concluded that the observed masseteric inhibition was caused by the unloading of periodontal mechanoreceptors and thus that these receptors may contribute to the jaw unloading reflex.     

How could pathologists improve the initial diagnosis of colitis? Evidence from an international workshop

BACKGROUND: The taking of multiple colorectal biopsies is in widespread use although there is little research into their benefit for the pathological diagnosis of inflammatory bowel disease. There is also still debate about appropriate morphological criteria for interpreting these biopsies. AIMS: To determine the effect of single versus multiple biopsies on the accuracy of diagnosis and to study the accuracy and reproducibility of the different criteria used in the diagnosis of multiple biopsies by expert and non-expert pathologists. METHOD: Thirteen expert and 12 non-expert international diagnostic histopathologists attended a workshop. Sixty cases with full follow up were viewed, blinded, in two rounds. Diagnoses were made on rectal biopsies and then full colonoscopic series. RESULTS: Experts correctly identified 24% of Crohn's disease cases (non-experts, 12%) from the rectal biopsies. This improved to 64% (non-experts, 60%) with the full series. The accuracy of the diagnosis of ulcerative colitis also improved slightly with the full series from 64% to 74% overall. Experts had a similar (moderate) level of agreement and accuracy to non-experts. For Crohn's disease, the likelihood ratios (LR) for the most important individual features were 12.4 for granulomas and 3.3 for focal or patchy inflammation. Features favouring ulcerative colitis were diffuse crypt architectural irregularity (LR, 3.4), general crypt epithelial polymorphs (LR, 3.7), and reduced crypt numbers (LR, 2.9). CONCLUSIONS: A full colonoscopic series gave more accurate diagnosis than a rectal biopsy. Accurate pathologists used the same evidence based criteria for multiple biopsies as for single biopsies.     

Defining duodenitis: quantitative histological study of mucosal responses and their correlations

Biopsies from 56 patients with endoscopically normal duodenal bulbs, duodenitis, or duodenal ulceration were studied for counts of plasma cells, polymorphs, and eosinophils and extent of gastric metaplasia, villous atrophy, and mucosal oedema. A correlation matrix showed that the counts of different types of plasma cells were closely correlated with each other and that there was also a close correlation between the presence of intraepithelial polymorphs, villous atrophy, and gastric metaplasia. Cluster and discriminant analysis indicated that the histological changes could be grouped by their statistical association into three simple categories: normal, which includes many cases incorrectly labelled in some classification systems as mild or chronic duodenitis; histologically defined mild duodenitis, characterised by an appreciable plasma cell response and oedema usually with intraepithelial polymorph infiltration and gastric metaplasia; and severe duodenitis, with an appreciable polymorph response and villous atrophy but decreased plasma cells. Decreased plasma cells may be an important indication of peptic ulceration.     

Blood lactate in trained cyclists during cycle ergometry at critical power

Summary The purposes of this investigation were to determine the validity of critical power (CP) as a measure of the work rate that can be maintained for a very long time without fatigue and to determine whether this corresponded with the maximal lactate steady-state (la_ss,max). Eight highly trained endurance cyclists (maximal oxygen uptake 74.1 ml · kg^–1 · min^–1, SD 5.3) completed four cycle ergometer tests to exhaustion at predetermined work rates (360, 425, 480 and 520 W). From these four co-ordinates of work and time to fatigue the regression of work limit on time limit was calculated for each individual (CP). The cyclists were then asked to exercise at their CP for 30 min. If CP could not be maintained, the resistance was reduced minimally to allow the subject to complete the test and maintain a blood lactate plateau. Capillary blood was sampled at 0, 5, 10, 20 and 30 min into exercise for the analysis of lactate. Six of the eight cyclists were unable to maintain CP for 30 min without fatigue. In these subjects, the mean power attained was 6.4% below that estimated by CP. Mean blood lactates (n = 8) reached a steady-state (8.9 mmol · l^–1, SD 1.6) during the last 20 min of exercise indicating that CP slightly overestimated la_{ss, max}. Individual blood lactates during the last 20 min of exercise were more closely related to the y-intercept of the CP curve (r=0.78, P<0.05) than either CP (0.34, NS) or mean power output (r=0.42, NS). The present investigation has shown that highly trained endurance cyclists can tolerate previously unreported levels of blood lactate during 30 min of exercise at or near their CP. Blood lactates during continuous exercise are higher than at the same work rate during an incremental test. The CP provides a simple and inexpensive means of assessing the exercise intensity which can be maintained continuously, while avoiding the methodological difficulties associated with ventilatory and lactate thresholds.     

Evaluation of the single radial haemolysis (SRH) technique for rubella antibody measurement.

Sera from 1258 individuals have been tested by four laboratories for rubella antibody by both the haemagglutination-inhibition and single radial haemolysis techniques. There was good agreement between the results obtained by the two methods. Although sheep red blood cells were used in the single radial haemolysis plates, no problems were encountered with sera from patients with infectious mononucleosis. The single haemolysis technique was found to be simple, convenient, and reliable, and suited to the rapid screening of large numbers of sera to assess susceptibility to rubella in the context of a vaccination campaign. However, since the technique does not detect anti-rubella IgM, it should not be used as the only test to investigate suspected recent infection.     

Cyclooxygenase-2 deficiency results in a loss of the anti-proliferative response to transforming growth factor-beta in human fibrotic lung fibroblasts and promotes bleomycin-induced pulmonary fibrosis in mice

Prostaglandin E(2) (PGE(2)) inhibits fibroblast proliferation and collagen production. Its synthesis by fibroblasts is induced by profibrotic mediators including transforming growth factor (TGF)-beta(1). However, in patients with pulmonary fibrosis, PGE(2) levels are decreased. In this study we examined the effect of TGF-beta(1) on PGE(2) synthesis, proliferation, collagen production, and cyclooxygenase (COX) mRNA levels in fibroblasts derived from fibrotic and nonfibrotic human lung. In addition, we examined the effect of bleomycin-induced pulmonary fibrosis in COX-2-deficient mice. We demonstrate that basal and TGF-beta(1)-induced PGE(2) synthesis is limited in fibroblasts from fibrotic lung. Functionally, this correlates with a loss of the anti-proliferative response to TGF-beta(1). This failure to induce PGE(2) synthesis is because of an inability to up-regulate COX-2 mRNA levels in these fibroblasts. Furthermore, mice deficient in COX-2 exhibit an enhanced response to bleomycin. We conclude that a decreased capacity to up-regulate COX-2 expression and COX-2-derived PGE(2) synthesis in the presence of increasing levels of profibrotic mediators such as TGF-beta(1) may lead to unopposed fibroblast proliferation and collagen synthesis and contribute to the pathogenesis of pulmonary fibrosis.     

Centrilobular histopathologic changes in liver transplant biopsies

We evaluated centrilobular histologic changes seen on post-orthotopic liver transplantation (OLT) biopsies to refine the pathologic diagnosis by systematic study of morphologic and clinical data with possible identification of prognostic criteria. A total of 110 biopsies with zone 3 pathology from 59 patients were reviewed and correlated with clinical findings. Within the first 6 months post-OLT (group I), 39 of 47 patients had combinations of centrilobular hepatocytic dropout, ballooning, and cholestasis on single or multiple biopsies attributed to perioperative ischemic/perfusion injury; 12 of 39 patients with all 3 features present had increased incidence of biliary complications and sepsis and decreased 1-year patient and graft survival; 17 of 39 patients with 2 of the 3 features had increased biliary complications but not decreased 1-year survival; and the remaining 8 of 47 patients had central venulitis associated with acute cellular rejection. After 6 months post-OLT (group II), 14 patients, including 2 from group I, had biopsies with centrilobular pathology; 8 of 14 had central venulitis related to rejection (acute, 4; chronic, 4), and fibrosis was seen in 8 (rejection, 6; cardiac problems, 2). In conclusion, combinations of centrilobular hepatocytic ballooning, dropout, and cholestasis are seen in association with reversible or irreversible ischemic/perfusion damage in the early post-OLT period. The presence of all 3 features is associated with a poor outcome. Central venulitis as a feature of acute/chronic rejection is seen at any time post-OLT and is not a predictor of poor graft/patient survival.