Lytic susceptibility of target cells to cytotoxic T cells is determined by their constitutive major histocompatibility complex class I antigen expression and cytokine-induced activation status

Cytotoxic T-cell lines (TCL) were raised in vitro using stimulator cells with a defined major histocompatibility complex (MHC) mismatch and tested in a cytotoxic chromium-release assay against haemopoietic and non-haemopoietic target cells from the original stimulator. Monoclonal antibody (mAb)-blocking experiments and simultaneous determination of MHC class I, class II, lymphocyte function-associated antigen-1 (LFA-1) and intracellular adhesion molecule-1 (ICAM-1) density by quantitative radioimmunometric methods and flow cytometry on target cells demonstrated that lysis was restricted by MHC class I and dependent upon the constitutive MHC class I antigen expression. Measurements showed a high constitutive expression of class I MHC antigens on peripheral blood mononuclear cells (PBMC), but a low one on keratinocytes (K). Also, PBMC were more susceptible to lysis by TCL than K. Interferon-gamma (IFN-gamma) treatment of K resulted in increased MHC class I antigen expression and enhanced lytic susceptibility to TCL. IFN-alpha and tumour necrosis factor-alpha (TNF-alpha) treatment, which did not modulate MHC class I antigen expression on K, did not influence the amount of K lysis either. None of the cytokines tested in this analysis, however, increased the expression of MHC class I, class II, ICAM-1 and LFA-1 on PBMC. Only IFN-gamma pretreatment showed a minimal, statistically significant increase in MHC class I antigen expression. In spite of the minimal effect of IFN-gamma and no effect of IFN-alpha on class I MHC expression, pretreatment of target cells with both cytokines considerably increased their lytic susceptibility. The mechanism of cytokine-induced enhanced lytic susceptibility to TCL was not explained by increased MHC class I, LFA-1 or ICAM-1 expression, since no correlation was found between surface expression of these molecules and lytic susceptibility to TCL. These data demonstrate that: (1) the constitutive density of MHC class I antigens determines the extent of TCL lysis; (2) IFN-gamma, and not IFN-alpha or TNF-alpha controls the amount of K target cell lysis by increasing their MHC class I antigen expression; and (3) IFN-gamma and IFN-alpha control the amount of PBMC target cell lysis by a mechanism independent of MHC class I, ICAM-1 or LFA-1 expression.

Cytoskeletal reorganization in NIH 3T3 fibroblasts expressing the ras oncogene

Expression of the Ha-ras oncogene in NIH 3T3 fibroblasts leads to a set point shift of cell volume regulation and causes an increase in cell volume by activation of Na+/H+ exchange and Na+, K+, 2Cl- cotransport. Since both ion transport systems are thought to be governed by the cytoskeleton, the aim of this study was to examine the alterations in growth characteristics and cytoskeletal organization due to the expression of the oncogene. The experiments were performed on NIH 3T3 fibroblasts transfected with a transforming Ha-ras MMTV-LTR construct and expressing the oncogene after treatment with low serum medium and 1 mumol/l dexamethasone (+ras cells). Transfected cells not expressing the oncogene (-ras cells) and treated with low serum medium, but without the addition of dexamethasone, served as controls. The growth characteristics were examined and the cytoskeletal architecture was visualized by indirect immunofluorescence microscopy using specific antibodies and fluorescent dyes. Expression of the ras oncogene was accompanied by a significant and serum-independent increase in proliferative activity irrespective from the coating of the dishes with attachment factors (poly-L-lysine, collagen type I). Both, -ras and +ras cells, proliferated slower on substrates coated with poly-L-lysine than on tissue culture plastic or collagen type I. Expression of the ras oncogene also resulted in a significant increase in cell volume which was independent from the substrate. +ras Cells became more elongated, exhibited long cytoplasmic protrusions and tended to detach when compared with -ras cells. Examination of the cytoskeletal architecture in +ras and -ras cells revealed marked differences such as a depolymerization of the stress fiber network to strongly fluorescent "focals" as well as the absence of vinculin-containing attachment plaques (focal contacts), a disorganization of non-muscle myosin and of cell surface fibronectin in +ras cells. In addition, a retraction of microtubules and vimentin filaments to the perinuclear region was also observed in +ras cells. For comparison, NIH 3T3 fibroblasts which were not transfected with the ras oncogene (0ras cells) and which were also subjected to the experimental conditions described above (low serum medium +/- dexamethasone), did not exhibit the cytoskeletal alterations as observed for +ras cells. The results demonstrate that the expression of ras oncogene causes not only profound alterations in the proliferative activity, cell volume and cell morphology, but also a marked reorganization of cytoskeletal architecture, which may participate in the altered regulation of volume-regulatory ion transporters in the cell membrane.

[Late pericardial tamponade: a dangerous complication of postoperative anticoagulation following heart surgery]

Late cardiac tamponade is a condition that presents with subtle signs and symptoms within days or weeks after cardiac surgery. During a one-year period, 16 patients, operated in our institution, developed this complication, mostly due to overdosage of anticoagulants. Diagnosis can be difficult and is best confirmed by echocardiography. The incidence of this dangerous complication is reportedly between 0.3 and 1%. The treatment consists in sub-xyphoid drainage when ever possible. In case of loculated or posterior tamponade, re-sternotomy might be necessary to assume complete decompression of the heart.

[Surgery of endocarditis in the drug dependent and HIV patient. A prospective comparison with conservative treatment]

The incidence of infective endocarditis in drug addicts is increasing with the spreading of intravenous drug abuse. The tricuspid valve is the most commonly involved valve followed by the mitral valve. We evaluated prospectively 22 patients with a mean age of 23 years, presenting with addiction-associated endocarditis endocarditis and referred to our institution during a three-year period. The tricuspid valve was involved in 13 instances, mitral valve in 4, mitral plus tricuspid valve in 5 patients and aortic valve in 1 case. Staphylococcus aureus was the most frequent infective organism (15x), followed by Streptococci (4x), Corynebacteria (2x) and one case with a mixed infection. Six patients were positive for an HIV-infection and 17 had evidence for a chronic viral hepatitis. Ten patients (3 of them HIV-seropositive) were treated surgically. Resection of the tricuspid valve with (1x) or without replacement (4x), resection of vegetations and valve repair (2x), mitral valve replacement (2x), aortic valve replacement (1x) were performed. In case of tricuspid endocarditis, the decision whether to proceed with resection, repair or replacement with a bioprosthesis was taken according to valve pathology and the psycho-social situation of the patient. When the vegetations involved only one leaflet and could be removed easily, vegetectomy with annuloplasty or with repair using autologous pericardium was performed. Valvulectomy without replacement was the chosen method for those where persistent or recurrent drug abuse could not be excluded. A bioprosthesis was inserted when the tricuspid valve was completely destroyed and there was a proven abstinence from drugs over a period of several weeks preoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)

[Problems of non-invasive diagnosis of congenital heart defects in adulthood]

Non-invasive assessment of adult congenital heart disease comprises Doppler echocardiography and magnetic resonance imaging (MRI). Doppler echocardiography represents the modality of choice to perform serial follow-up and MRI is used as supplementary method in the diagnosis of congenital heart disease in adults. The spectrum of congenital heart disease in adults encompasses (a) uncorrected and newly detected defects; (b) palliatively corrected and totally corrected defects. In general, diagnostic modalities must be able to fulfill the following requirements: (a) sequential morphologic analysis; (b) assessment of hemodynamics. Sequential morphologic analysis using 2-dimensional echocardiography includes determination of the situs of the atria, atrio-ventricular and ventriculo-arterial connections. Non-invasive assessment of hemodynamics is performed with the Doppler technique and comprises diagnosis and quantitation of (a) (residual) shunt lesions, (b) valvular regurgitation and (c) valvular, subvalvular, supravalvular and infundibular stenosis as well as pressure gradients across anastomoses and intracavitary or intercavitary gradients, respectively. Pulmonary vascular resistance cannot be assessed quantitatively by Doppler. However, the determination of the end-diastolic gradient between the pulmonary artery and the right ventricle in the presence of pulmonic regurgitation allows estimation of the diastolic pulmonary artery pressure.

[Role of heart transplantation in the treatment of complex congenital malformations in adolescents and adults]

The number of pediatric heart transplants for complex congenital heart disease has increased in recent years, but little experience has been reported in the adolescent and adult population. Between 1987 and 1992, 6 patients (mean age 24 years, range 14 to 42) underwent transplant in our institution because of structural congenital heart disease with or without prior palliative operation or definitive repair. The diagnose covered: congenitally corrected transposition of the great vessels, late systemic ventricular failure after surgically corrected transposition of the great arteries, left superior vena cava, and tricuspid atresia with right ventricular hypoplasia. The palliative repairs included modified Blalock-Taussig shunt, cavo-pulmonary Glenn shunt, two aorto-pulmonary Waterstone shunts, two Blalock-Hanlon atrioseptectomies and one pulmonary valvotomy by the method of Brock. One patient had undergone pulmonary artery banding, in two patients atrial repair by Senning's technique had been performed for definitive repair of transposition of the great arteries. Donor cardiectomy was modified to remove complete inflow and outflow tissue and transplantation was performed without prosthetic material in all patients, in no case was deep hypothermic arrest necessary. There was no early or late mortality after a mean follow-up of 28 months. Postoperative echocardiography and cardiac catheterization demonstrated perfect anatomical and functional results. There was no early or late mortality after a mean follow-up of 28 months. Postoperative echocardiography and cardiac catheterization demonstrated perfect anatomical and functional results. Adult patients with complex congenital cardiac diseases can be transplanted with a very low perioperative risk, even after several prior operative procedures.(ABSTRACT TRUNCATED AT 250 WORDS)

[Right ventricular dysplasia (right ventricular cardiomyopathy). Clinical aspects, diagnosis and course in 15 patients from the Zurich area]

Fifteen patients (8 men, 7 women) with right ventricular dysplasia (RVS) from the greater Zürich area are described. Two thirds of these patients were younger than 30 years at first manifestation. 12 presented with ventricular tachycardia of left bundle branch block type. Other forms of arrhythmia (supraventricular tachycardia, sinus node dysfunction) or condition disturbances were documented in 9 subjects. 6 patients had additional symptoms of congestive heart failure; in 3 of them this was the only symptom. 12-lead ECG at rest showed precordial T-negativity (1 pacemaker ECG not interpretable) in 14/15 subjects. Signal averaged ECG revealed late potentials as well as spectral turbulence in the Y or Z leads. Echocardiography yielded typical local abnormalities in the whole study cohort and all but 2 patients showed decreased right ventricular ejection fraction and right heart dilatation. Moreover, left ventricular ejection fraction was concomitantly impaired in 6 subjects. 4 of these 6 individuals suffered from further impairment of left ventricular function within a time period of 19 to 47 months. Recurrent ventricular tachycardia was documented in 11 patients. 2 subjects underwent heart transplantation because of severe progressive right heart failure. One subject died shortly after diagnosis and autopsy confirmed nearly total absence of right ventricular myocardium. This extreme form of right ventricular dysplasia corresponds to Uhl's anomaly. Thus, recurrent ventricular arrhythmias, in particular ventricular tachycardia of left bundle branch block type, together with precordial T-negativity without signs of ischemic heart disease, is highly suggestive of RVD. Echocardiography allows reliable diagnosis. Concomitant left ventricular involvement is frequent. Considering that the etiology and pathogenesis of this disease are unknown, the term right ventricular cardiomyopathy, rather than right ventricular dysplasia, seems more accurate.

Effects of HOE 694--a novel inhibitor of Na+/H+ exchange--on NIH 3T3 fibroblasts expressing the RAS oncogene

Among the sequelae of ras oncogene expression are intracellular alkalinization and increase of cell volume, both phenomena attributed at least in part to activation of the Na+/H+ exchanger. The present study was performed to elucidate the effects of HOE 694--a novel inhibitor of the Na+/H+ exchanger--on intracellular pH, cell volume, cytoarchitecture and cell proliferation of ras oncogene expressing NIH 3T3 fibroblasts. Following transient exposure of the cells to 20 mmol/l NH3/NH4+, intracellular pH decreases sharply. The following slow realkalinization is completely blocked by 10 mumol/1 HOE 694. Half-maximal inhibition is achieved by 100 nmol/l HOE 694. Cell proliferation is inhibited by HOE 694 with similar potency, whereas the increase in cell volume and cytoskeletal transformation are not prevented, even by 10 mumol/l HOE 694.

Association of mononuclear cells and eosinophils with airway resistance and responsiveness in rat pulmonary inflammatory responses

To evaluate the association of various leukocytes with pulmonary resistance and methacholine responsiveness, we induced pulmonary eosinophil-rich inflammation in IgE-sensitized (ovalbumin) Sprague Dawley rats. Sensitized rats were challenged with either relevant (OA) or irrelevant antigen by tracheal insufflation a) with no other treatment, b) in conjunction with intravenous Sephadex beads pretreatment, or c) with antigen coupled covalently to Sepharose beads. About 24 h after antigen challenge, respiratory system resistance (Rrs), response to aerosolized methacholine, and pulmonary histopathology were evaluated. Challenge with OA, insufflation with Sepharose, and treatment with i.v. Sephadex all independently increased inflammatory cell infiltrates, but the combination of OA with the other agents did not significantly enhance the inflammatory response over OA alone. Interactive stepwise regression techniques were utilized to identify correlates for Rrs and methacholine responsiveness. Mononuclear cell score was a significant predictor (p < .01) for Rrs, and insufflation of Sepharose had a significant independent effect on Rrs (p = .01) above that predicted by mononuclear cell infiltrates. Conversely, eosinophil score and neutrophil score were not significant predictors for Rrs, and challenges with antigen or Sephadex had no significant independent effect on Rrs beyond that predicted from mononuclear cell infiltrates. Eosinophil score was the only significant histological predictor for methacholine responsiveness (p < .0001). Challenges with Sephadex, antigen and Sepharose did not significantly change methacholine responsiveness independently of the changes associated with eosinophil infiltrates. These findings suggest that mononuclear cells and eosinophils contribute to increases in airway resistance and responsiveness, respectively, following the induction of pulmonary inflammation by both allergic and non-allergic stimuli.

[Doppler echocardiography diagnosis in heart failure]

The evaluation of heart failure is one of the most common reasons for echocardiography in the adult population. Within this context, Doppler echocardiography as a noninvasive diagnostic procedure is able to provide immediate and relevant information on functional and structural changes underlying the clinical syndrome of heart failure. Analysis comprises global left- and right-ventricular systolic function, regional wall motion and diastolic function. Evidence of normal systolic left-ventricular function has been reported in up to 30% of the patients with clinical signs of heart failure, suggesting abnormal diastolic function as the origin for the symptoms of heart failure. Therefore, noninvasive assessment of heart failure by Doppler echocardiography must include analysis of systolic as well as diastolic left-ventricular function.

The role of calcium in cell shrinkage and intracellular alkalinization by bradykinin in Ha-ras oncogene expressing cells

In ras oncogene expressing cells, bradykinin leads to intracellular alkalinization by activation of the Na+/H+ exchanger. This effect is paralleled by oscillatory increase of intracellular calcium activity and cell shrinkage. Staurosporine (1 mumol/l) is not sufficient to prevent bradykinin induced intracellular alkalinization, thus pointing to a protein kinase C independent pathway for the activation of Na+/H+ exchange. The present study has been performed to elucidate, whether the increase of intracellular calcium contributes to cell shrinkage and activation of the Na+/H+ exchanger. To this end, the effects of the calcium ionophore ionomycin have been tested. Ionomycin leads to a dose dependent increase of intracellular calcium activity. At 100 nmol/l ionomycin intracellular calcium is increased from 114 +/- 17 nmol/l to 342 +/- 24 nmol/l (n = 9), a value within the range of intracellular calcium concentrations following application of bradykinin. The calcium increase is paralleled by a decrease of cell volume by 12 +/- 2% (n = 5) and an increase of intracellular pH from 6.78 +/- 0.02 to 6.90 +/- 0.03 (n = 11), values similar to those following application of bradykinin. The alkalinizing effect of ionomycin is completely abolished in the presence of the novel Na+/H+ exchange inhibitor HOE 694 (10 mumol/l), but is not inhibited by 1 mumol/l staurosporine. Inhibition of K+ and Cl- channels by barium (5 mmol/l) and ochratoxin-A (5 mumol/l) prevents both ionomycin induced cell shrinkage and protein kinase C independent intracellular alkalinization. It is concluded that bradykinin leads to intracellular alkalinization mainly by increasing intracellular calcium concentration. Calcium triggers calcium sensitive K+ channels, and presumably Cl- channels, the subsequent loss of cellular KCl leads to cell shrinkage which, in turn, activates Na+/H+ exchange.

Cell shrinkage stimulates bradykinin-induced cell membrane potential oscillations in NIH 3T3 fibroblasts expressing the ras-oncogene

In NIH 3T3 fibroblasts expressing the Ha-ras oncogene (+ ras) bradykinin leads to sustained oscillations of cell membrane potential due to oscillations of intracellular Ca2+ with subsequent activation of Ca(2+)-sensitive K+ channels. In cells not expressing the oncogene (-ras), bradykinin leads only to a single transient hyperpolarization of the cell membrane. The present study has been performed to elucidate the possible interaction of cell volume, intracellular pH and bradykinin-induced oscillations of the cell membrane potential. Bradykinin leads to cell shrinkage and intracellular alkalinization of both + ras cells and -ras cells. Inhibition of Na+/H+ exchanger by HOE 694 abolishes the bradykinin-induced alkalinization but does not significantly interfere with the bradykinin-induced oscillations of cell membrane potential. In contrast, prevention of bradykinin-induced cell shrinkage by simultaneous reduction of extracellular osmolarity blunts the oscillations. Thus, cell shrinkage stimulates bradykinin-induced oscillations of cell membrane potential. On the other hand, cell shrinkage alone does not elicit oscillations unless, in addition, Ca2+ entry is stimulated by ionomycin.

Correlation of minor histocompatibility antigen-specific cytotoxic T lymphocytes with graft-versus-host disease status and analyses of tissue distribution of their target antigens

Peripheral blood mononuclear cells (PBMC) from 17 patients receiving HLA-identical sibling bone marrow grafts were stimulated with host pretransplant PBMC. Cytotoxic T-cell lines (TCL) with specificity for host pretransplant PBMC were obtained from 9 of these patients, all presenting with severe graft-versus-host disease (GVHD), but from none of the remaining cases lacking evidence of disease. Cytotoxic TCL were specific for host targets and failed to lyse donor cells. Monoclonal antibodies (MoAbs) blocking experiments and donor population screening analyses demonstrated that minor histocompatibility antigen (MiHA)-specific lysis of host targets was restricted by class I major histocompatibility complex (MHC) determinants. Whereas hematopoietic cells such as phytohemagglutinin (PHA) blasts or lymphoblastoid cell lines were susceptible to lysis by MiHA-specific TCL, keratinocytes (K) representing the natural targets of GVHD were quite resistant. Quantitative radioimmunometric measurements indicated very low constitutive expression of class I MHC antigens on K targets, which was readily increased by treatment with interferon-gamma (IFN-gamma). IFN-gamma treatment at the same time rendered these cells susceptible to lysis by MiHA-specific TCL. Host leukemic cells of 3 patients were recognized by MiHA-specific TCL in a chromium release assay and in one experiment host leukemic cells were effectively killed and their growth specifically inhibited in a leukemia colony assay by a clone. These data demonstrate that (1) host-specific cytotoxic TCL are detected exclusively in the PB of patients with acute GVHD grades II through IV after allogeneic matched bone marrow transplantation, and (2) their target antigens are simultaneously expressed on several host cell lines, including lymphoblastoid cell lines, PHA blasts, leukemic cells, and K. We also extend previous findings by showing that, besides the expression of the nominal MiHA, the density of the restricting class I MHC elements also crucially determines the extent of TCL lysis. Because of its capacity to enhance class I MHC antigen expression, IFN-gamma represents a key cytokine for determining the susceptibility of MiHA targets for lysis by TCL and clones, and in one patient an MiHA-specific clone recognized host leukemic cells and also inhibited host leukemic cell growth in a colony inhibition assay.

Hydroperoxide metabolism in rat liver. K+ channel activation, cell volume changes and eicosanoid formation

Addition of t-butylhydroperoxide (0.2 mM) to isolated perfused rat liver led to a net K+ release of 7.2 +/- 0.2 mumol/g within 8 min and a net K+ reuptake of 6.6 +/- 0.4 mumol/g following withdrawal of the hydroperoxide, in line with earlier findings by Sies et al. [Sies, H., Gerstenecker, C., Summer, K. H., Menzel, H. & Flohé, R. (1974) in Glutathione (Flohé, L., Benöhr, C., Sies, H., Waller, H. D., eds) pp. 261-276, G. Thieme Publ. Stuttgart]. Net K+ release roughly paralleled the amount of GSSG released from the liver under the influence of the hydroperoxide. The t-butylhydroperoxide-induced K+ efflux was inhibited by approximately 70% in the presence of Ba2+ (1 mM), by 30% in Ca(2+)-free perfusions and was decreased by 50-60% when the intracellular Ca2+ stores were simultaneously depleted by repeated additions of phenylephrine. t-Butylhydroperoxide-induced K+ efflux was accompanied by a decrease of the intracellular water space by 58 +/- 14 microliter/g (n = 4), corresponding to a 10% cell shrinkage. The effect of t-butylhydroperoxide on cell volume was inhibited by 70-80% in the presence of Ba2+. In isolated rat hepatocytes treatment with t-butylhydroperoxide led to a slight hyperpolarization of the membrane at concentrations of 100 nM, but marked hyperpolarization occurred at t-butylhydroperoxide concentrations above 10 microM. t-Butylhydroperoxide (0.2 mM) transiently increased the portal-perfusion pressure by 3.3 +/- 0.6 cm H2O (n = 18), due to a slight stimulation of prostaglandin-D2 release under the influence of the hydroperoxide. In the presence of Ba2+ (1 mM), t-butylhydroperoxide increased the perfusion pressure by 12.7 +/- 1.2 cm H2O (n = 9) and produced an approximately tenfold increase of prostaglandin-D2 and thromboxane-B2 release. Under these conditions, glucose output from the liver rose from 0.9 +/- 0.03 to 2.9 +/- 0.7 mumol.g-1.min-1 (n = 4) with a time course roughly resembling that of portal-pressure increase and prostaglandin-D2 overflow. These effects were largely abolished in the presence of ibuprofen or the thromboxane-receptor-antagonist BM 13.177. The t-butylhydroperoxide effects on perfusion pressure, glucose and eicosanoid output were also enhanced in the presence of insulin or during hypotonic exposure; i.e. conditions known to swell hepatocytes, but not during hyperosmotic exposure. The data suggest that t-butylhydroperoxide induces liver-cell shrinkage and hyperpolarization of the plasma membrane due to activation of Ba(2+)-sensitive K+ channels.(ABSTRACT TRUNCATED AT 400 WORDS)

Retrograde ascending aortic dissection: a diagnostic and therapeutic challenge

Aortic dissection with an entrance tear in the transverse aorta is generally considered to have the highest acute fatality rate of any type of dissection and the direction of its extension is the most difficult to predict. In a prospective study, we evaluated 61 consecutive patients (mean age 56.7 years, ranging from 21 to 75 years), presenting with ascending aortic dissection during a 36-month-period and tried to clarify the incidence of retrograde ascending aortic dissection. In 49 patients (80.3%), the intimal tear was located in the ascending aorta, whereas the dissection originated in the transverse aorta in 12 patients (19.7%); in this latter group, extension was strictly retrograde in 5 patients and in both directions in 7 patients. Three patients died before operation; 58 patients underwent aortic replacement/repair under moderate hypothermia; if the primary tear extended into the transverse aorta or was not found in the ascending aorta, the aortic arch was explored during a brief period of deep hypothermic circulatory arrest. The overall operative mortality was 12.1% (7/58); it was 10.4% (5/48) in ascending aortic dissection and 20% (2/10) in dissection of the transverse aorta. Age (P < 0.005), concomitant coronary artery disease (P < 0.01) and the site of intimal tear (P < 0.01) were significant predictive factors of operative risk. A tear in the transverse aorta is almost always associated with retrograde dissection and may simulate dissection with the entrance tear in the ascending aorta. Localization of the entrance tear remains a diagnostic challenge in aortic dissection but Doppler-echocardiography had a high sensitivity in this series (96.7%).(ABSTRACT TRUNCATED AT 250 WORDS)

The biological significance of cell volume

To survive, cells have to avoid excessive alterations of their volume. To this end, cells have developed a complex machinery of cell volume regulatory mechanisms comprising transport across the cell membrane and metabolism. Upon cell swelling, they loose electrolytes mainly via selective K+ channels and unselective ion channels and/or KCl symport, upon cell shrinkage they accumulate ions by Na+,K+,2Cl- cotransport and parallel operation of Na+/H+ exchange and Cl-/HCO3- exchange. In addition, cell shrinkage stimulates glycogenolysis, proteolysis and formation of organic osmolytes such as amino acids, methylamines and polyols. Cell swelling stimulates formation of glycogen and proteins and cellular release of organic osmolytes. Alterations of cell volume do play a crucial role in the regulation of cell function, as illustrated by four examples: 1. Epithelial transport may lead to cell swelling, which then triggers volume regulatory mechanisms modifying transcellular transport. 2. Insulin swells hepatocytes by activation of Na+,K+,2Cl- cotransport and Na+/H+ exchange, glucagon shrinks those cells by activation of ion channels. The respective volume changes participate in the regulation of cellular protein and glycogen metabolism by these hormones. 3. Growth factors and expression of ras oncogene activate Na+,K+,2Cl- cotransport and Na+/H+ exchange, leading to the respective cell swelling. 4. Hepatocyte swelling triggers a hepatorenal reflex decreasing renal blood flow.

Prognostic factors in medullary thyroid carcinoma: evaluation of 741 patients from the German Medullary Thyroid Carcinoma Register

A retrospective study of 741 patients with medullary thyroid carcinoma diagnosed between 1967 and 1991 was carried out by members of the German Medullary Thyroid Carcinoma Study Group to evaluate prognostic factors. A total of 559 patients (75%) were considered to have sporadic disease, and 182 (25%) had the familial type. The sex ratio (male to female) was 1:1.4 in sporadic disease patients, and the mean age at diagnosis was 45.9 years (range 5-81 years). For familial disease patients the sex ratio was 1:1.1, and the mean age at diagnosis was 33.4 (range 5-77 years). The follow-up time for 630 patients ranged from 1 month to 20.8 years (mean 13.0 years). The overall adjusted survival rate was 86.7% at 5 years and 64.2% at 10 years. In a univariate analysis the stage of disease at diagnosis, age, sex, and type of disease (sporadic, familial) were relevant prognostic factors, with a better prognosis for young female patients with familial disease and diagnosed at an early stage. In a multivariate proportional hazards analysis, the difference in the survival rate of patients with familial disease versus those with the sporadic form disappeared, while prognostic information provided by age and sex was still significant. The poorer prognosis of patients with sporadic medullary thyroid carcinoma may be related to the patients' older age at detection and more advanced tumor stage at diagnosis. There seems to be no difference in biological behavior between tumors of the sporadic and those of the familial type.

Well-differentiated thymic carcinoma. An organotypical low-grade carcinoma with relationship to cortical thymoma

Based on a study of 26 cases, the well-differentiated thymic carcinoma is described as a distinct organotypical carcinoma of the thymus with low-grade malignancy. It is characterized by a predominance of epithelial cells with usually low mitotic rate, an epidermoid differentiation with slight to moderate cytological atypia, the constant presence of interepithelial immature cortical thymocytes, lobular growth, and formation of epithelial palisades around perivascular spaces. The tumor occurs at age 14 to 76 years in both sexes. An association with myasthenia gravis is found in 77% of the patients, and 83% of the tumors show invasion of adjacent organs or endothoracic metastasis at primary operation. This rate is higher than in cortical thymomas (47%) but lower than in other thymic carcinomas (92%). Two of 18 patients with follow-up died of tumor recurrence and pleural metastasis. Well-differentiated thymic carcinoma can be related to cortical thymoma by common morphological features and a similar immunophenotype of epithelial cells. It must be differentiated from the lymphocyte-depleted cortical thymomas after corticosteroid treatment and from the benign epithelial-rich medullary thymomas.

Congenital cleft of the anterior tricuspid leaflet with severe tricuspid regurgitation in adults

OBJECTIVES AND BACKGROUND

Severe primary tricuspid regurgitation in the adult is a rare finding. This study describes the diagnostic findings and the treatment of an isolated congenital cleft of the anterior leaflet of the tricuspid valve as the morphologic substrate for severe tricuspid regurgitation.

METHODS

The clinical, echocardiographic findings and the follow-up findings of five patients (all male, 20 to 56 years old) with this disorder are described. Four of the five patients underwent cardiac surgery that confirmed the diagnosis.

RESULTS

In three of five patients, exertional fatigue was the limiting symptom (New York Heart Association functional classes II and III). The clinical findings included a holosystolic murmur and supraventricular arrhythmias in all patients. Cardiac catheterization, performed in four patients, yielded the incorrect diagnosis of Ebstein's anomaly in three. In one patient the cleft was associated with an atrial septal defect of the secundum type. In four of five patients successful reconstruction of the tricuspid valve with a DeVega annuloplasty was performed. One patient had a partial excision of the right atrium, and one had a closure of a coexisting atrial septal defect. One patient refused operation.

CONCLUSIONS

Tricuspid valve anomalies can be accurately identified by Doppler echocardiography. Surgical repair is the treatment of choice in patients with severe tricuspid regurgitation due to a congenital cleft of the anterior leaflet of the tricuspid valve.

Active autoimmune gastritis without total atrophy of the glands

To date, autoimmune gastritis has been diagnosed for the most part only when total atrophy of the oxyntic glands is detected. On the basis of 40 patients without total atrophy of the glands, and with parietal cell antibodies in the serum, we show that the diagnosis of type A gastritis is also possible in the pre-atrophic stage. The histological criteria for the diagnosis of active autoimmune gastritis without total atrophy of the glands are 1. usually dense, diffuse locally emphasized lymphocytic infiltration of the lamina propria between the glands in the oxyntic mucosa, 2. focal destruction of individual glands in the corpus of the stomach by lymphocytes, and 3. reactive pseudohypertrophy of the parietal cells. A comparison with a group of patients with autoimmune gastritis and total atrophy of the glands shows that in active autoimmune gastritis, too, women are more frequently affected than men (in both groups, the sex ratio is approximately 3:1). Patients without atrophy of the glands are, on average, about 12 years younger than those with "burnt out" type A gastritis (average age 69.98:57.80 years). While in the case of burnt out type A gastritis, no colonisation with Helicobacter pylori was to be found, such colonisation was demonstrated for the corpus mucosa in 22.5%, and for the antral mucosa in 15.0%. In 27.5% a minimal or low-grade inactive superficial gastritis, as may be seen after eradication of Helicobacter pylori, was additionally diagnosed in the antrum. A knowledge of the histological appearance of the pre-atrophic stage of type A gastritis might be of importance for the possible prevention of pernicious anaemia.(ABSTRACT TRUNCATED AT 250 WORDS)