Additional Evidence for Re-entry Within the Bundle Branches in Man

A repetitive, non-paced ventricular beat (V3) often occurs during ventricular extrastimulus testing at short coupling intervals when critical retrograde His-Purkinje conduction delay is achieved. Though re-entry within the bundle branches has been proposed as the mechanism for V3, it has been difficult to exclude local re-entry. In the present case, we consistently recorded a right bundle branch potential as well as a bundle of His potential before each V3. The anterograde activation sequence of these potentials provides evidence against local re-entry and supports re-entry involving the bundle branches as the mechanism for V3.     

PRIMARY SJOGREN'S SYNDROME IN NORTH EAST ENGLAND-A LONGITUDINAL STUDY

We have documented the initial clinical features of 100 patientswith primary Sjöigren's syndrome (SS) together with theresults of their baseline investigations. The evolution of thedisease in these patients has been followed for a median of34 months (range 3–84 months). The majority of patientswere females aged 40–60 years, and common clinical featuresincluded eye symptoms (100%), xerostomia (100%), polyarthralgia(94%), Raynaud's phenomenon (81%) and salivary gland swelling(47%). Thyroid disease was relatively common (14%) while otherendocrine disease was rare. Four patients died during follow-up,and three cases of lymphoma were detected. Other serious complicationsincluded pericarditis (10%), pleuroparenchymal lung disease(9%), renal tubular acidosis (3%) and cerebrovascular accidents(2%). The presence of anti-Ro antibodies identifies patientswith more severe systemic disease. Spontaneous improvement occurredin 12 patients, while steroids were required for specific complicationsin 18. Overall, although lymphoma was found to excess in ourgroup, the high mortality reported with primary SS elsewherewas not seen. KEY WORDS: Primary Sjogren's syndrome, Anti-Ro antibody, Endocrine, Exocrine, Lymphoma     

Changes in Sertoli Cell Function in vitro Induced by Nitrobenzene

Changes in Sertoli Cell Function in vitro Induced by Nitrobenzene.ALLENBY, G., SHARPE, R. M., AND FOSTER, P. M. D. (1990). Fundam.Appl. Toxicol 14, 364–375. Nitrobenzene (NB) has beenidentified as a testicular toxicant In vivo, but its site ofaction remains unknown. In the present study, the effect ofNB on the Sertoli cell was assessed in vitro using Sertoli celland Sertoli-germ cell cocultures. The parameters measured werethe exfoliation of germ cells; the secretion of lactate, pyruvate,and inhibin; and gross cellular morphology. The effect of meta-dinitrobenzene(mDNB), a related compound which is a known Sertoli cell toxicant,was assessed for comparison. Gross morphological changes includingvacuolation of Sertoli cells were observed following treatmentof cultures with 10^–3 M NB. Exposure of cocultures toNB also resulted in dose-dependent exfoliation of predominantlyviable germ cells. NB (>5 ? 10^–4 m) and mDNB at thesingle dose level used (10^–3 m) stimulated the secretionof lactate and pyruvate significantly by Sertoli cells, an effectthat was more marked in the absence of germ cells. Comparablechanges were observed in follicle stimulating hormone (FSH)-stimulatedcultures. Inhibin secretion by Sertoli cells was also alteredby exposure to NB but in a biphasic manner, with low (10^–8to 10^–6 m) and high (10^–4 to 10^–3 m) dosesenhancing inhibin secretion while intermediate (10^–5 M)doses had no effect. These effects were evident in both culturesystems but inhibin secretion by Sertoli-germ cell cocultureswas always greater than that by Sertoli cell cultures. However,these effects of NB on inhibin secretion were not evident inFSH-stimulated cultures. In contrast to the effects of NB, mDNBhad no effect on basal secretion of inhibin but blocked thestimulatory effect of FSH. It is concluded that NB, like mDNB,is probably a Sertoli cell toxicant in view of its similar disruptiveeffects on various parameters of Sertoli cell function. However,NB is far less toxic than mDNB at equivalent concentrationsin vitro The present study is the first to evaluate the potentialof inhibin secretion by Sertoli cells in culture as an additionalmarker of toxicant action, and concludes that it merits furtherstudy in this context.     

The brown bowel syndrome: a possible smooth muscle mitochondrial myopathy?

Two cases of lipofuscinosis of the gastrointestinal tract are described, and a mitochondrial origin of the pigment is proposed. The mechanism of formation of lipofuscin is discussed, with particular reference to the maintenance of structurally and functionally intact mitochondrial membranes. The central role of vitamin E is considered, and its biochemical significance to mitochondrial metabolism is emphasized. Comparisons are drawn between the abnormalities demonstrated within the smooth muscle cells of the two cases described, and the muscle cells observed in cases of skeletal muscle myopathies of mitochondrial origin. It is proposed that lipofuscinosis of the gastrointestinal tract, otherwise known as the 'brown bowel syndrome', may be regarded as a smooth muscle myopathy of mitochondrial origin.