Electrophysiological effects of amrinone and milrinone in an isolated canine cardiac tissue model of ischemia and reperfusion

The purpose of this study was to determine if amrinone or milrinone after the electrophysiological responses of canine ventricular tissues to "ischemia" or reperfusion. Isolated canine Purkinje tissue-papillary muscle preparations were studied using standard microelectrode techniques. Tissues were superfused for 10 min with a solution that mimicked ischemia (hypoxia, acidosis, elevated lactate levels and zero substrate). Reperfusion with normal Tyrode's solution was then instituted for 60 min. Next, tissues were equilibrated with amrinone (5.3 X 10(-4) M) or milrinone (2.5 X 10(-4) M) for 15 min and the protocol was repeated with drug in all solutions. Without drug, ischemic conditions resulted in moderate depolarization of Purkinje and muscle tissues. Reperfusion caused a rapid hyperpolarization in Purkinje tissue. This was followed by a phase of mild depolarization associated with enhanced pacemaker activity. All preparations recovered by 45 min of reperfusion. With amrinone or milrinone present, the changes in membrane potential induced by conditions of ischemia and reperfusion were not different from control. However, an early phase of very rapid ectopic activity was seen during reperfusion with amrinone or milrinone. This ectopic activity had a constant cycle length during the pauses in stimulation. However, irregular patterns of spontaneous and driven beats were observed when electrical stimulation was superimposed on the ectopic activity. Amrinone and milrinone also increased pacemaker activity in Purkinje tissue but this occurred later in reperfusion. This study demonstrates that amrinone and milrinone sensitize isolated canine ventricular tissues to the arrhythmogenic effects of reperfusion. The mechanism underlying the arrhythmic activity elicited by the bipyridines is not clear, but may involve re-entry or abnormal automaticity.     

Triperidin (Norakin): separation, stability and structure of stereoisomers

The antiparkinsonian triperiden (1; as hydrochloride Norakin) is a mixture of the stereoisomers 1a and 1b. Their identification and separation by chromatographic methods or fractional crystallisation of the tartrates is described. By means of IR- und 13C-NMR spectral data structures of 1a and 1b are proposed. Under proton catalysis 1b racemizes to 1a. In acidic solution (heating in 0.1 mol.1-1 HCl or storage in gastric juice at 37 degrees C) hydrolysis of 1 takes place and four isomeric products were observed (Z1-Z4), which arise by cleavage of the cyclopropyl moiety. The main product Z2 was identified as the 2"-hydroxy derivative. The solid drug is stable at least for 5 years.     

Deregulation of the G1/S-phase control in human testicular germ cell tumours

Deregulated cell cycle and defective genome-integrity checkpoints are among the hallmarks of cancer.Here we summarize our recent studies of key components of the GI/S machinery in normal human spermatogenesis, and their abnormalities in testicular germ cell tumours (TGCTs), with special emphasis on carcinoma in situ lesions (CIS). Our combined immunohistochemical and immunoblotting analyses of normal human adult and fetal testes, CIS, seminomas, embryonal carcinomas, and teratomas, revealed an 'unorthodox' spectrum of defects within the so-called RB pathway in TGCTs. The early aberrations included lack of expression of the retinoblastoma tumour suppressor (pRB) and the CDK inhibitor pl9ink4d, and overexpression of cyclin D2. Progression from CIS to invasive TGCTswas associated with loss of another two CDK inhibitors and tumour suppressors: pl6ink4a and pl8ink4c. We also found the lack of pRB and pl9ink4d in fetal gonocytes, the candidate target cell for all types of TGCTs. These findings, together with the status of the Chk2-p53 DNA-integrity checkpoint, are considered in relation to the origin, biology and pathogenesis of TGCTs, and potential implications of the GI/S defects for the curability of these tumours.     

Meningioma presenting as an intraoral mass in a patient with neurofibromatosis type 1

A 77-year-old woman with neurofibromatosis type 1 presented with ill-fitting dentures due to intraoral extension of a right temporal fossa mass. Computed tomographic scanning demonstrated that the masticator space mass bowed the zygomatic arch and remodeled the lateral orbit and maxillary sinus walls, findings that were consistent with the clinical diagnosis of a neurofibroma with possible malignant transformation. However, light microscopic, immunohistochemical, and ultrastructural examination of tissue from an incisional biopsy specimen were diagnostic of meningioma. This case illustrates that the clinicopathologic differential diagnosis of an enlarging mass in patient with neurofibromatosis should include sporadic, unrelated neoplasms as well as tumors known to be associated with the syndrome.     

Fat in the intestine as a regulator of appetite--role of CCK

The present review summarizes the appetite-suppressing effects of intestinal fat in the regulation of food intake in humans, with a special focus on the role of cholecystokinin (CCK). Current evidence supports a role for intestinal fat (especially long-chain free fatty acids) acting via the peptide CCK as a physiological satiety pathway. The regulation of satiety is, however, complex and it is not surprising that multiple control systems exist. It is interesting to note that nutrients, such as hydrolysis products of fat in the small intestine, stimulate the release of satiety peptides, such as CCK or PYY, that serve as satiety signals. CCK, released from the gastrointestinal tract by the local action of digested food, exerts various functions: stimulation of gallbladder contraction and exocrine pancreatic secretion, inhibition of gastric emptying, and inhibition of appetite. CCK functions therefore (1) as a positive feedback signal to stimulate digestive processes and (2) as negative feedback signal to limit the amount of food consumed during an individual meal.     

Proximal tubular epithelial cell integrins respond to high glucose by altered cell-matrix interactions and differentially regulate matrixin expression

Thickening of the tubular basement membrane (TBM) occurs in diabetic nephropathy, but the effects of high glucose on the functional aspects of proximal tubular epithelial cells are not clearly understood. In the present study, we examined the effects of elevated glucose concentrations on (a) integrin expression by human proximal tubular epithelial cells (HK-2) and integrin-mediated interactions with type IV collagen (colIV) and laminin, major components of TBM; (b) the expression of matrixins/matrix metalloproteinases (MMPs), which is regulated by integrins; and (c) the expression of tissue inhibitors of metalloproteinases (TIMPs). HK-2 cells cultured in 25 mM glucose underwent a reduction of the expression of alpha3, beta1, alpha(v)beta3, and alpha5 integrin subunits, with a concomitant increase of the alpha2 subunit, compared with cells grown in 5 mM glucose. Adhesion experiments demonstrated that high glucose led to increased cell adhesion on either colIV or laminin. Experiments of competition of adhesion using anti-integrin antibodies indicated that HK-2 cells in 5 mM glucose used mainly alpha(v)beta3 and alpha5beta1 integrins to adhere to colIV, whereas in 25 mM glucose they additionally used alpha2beta1. In the case of laminin, a beta1-mediated adhesion was observed when HK-2 cells were in 5 mM glucose, whereas in 25 mM glucose, alpha2beta1 and alpha(v)beta3 were also involved. Elevated glucose concentrations resulted in decreased expression of MMP-9 and MMP-2, whereas an increase in TIMP-1 and a decrease in TIMP-2 expression were observed. We also examined which integrins mediated the expression and secretion of matrixins MMP-2 and MMP-9. Ligation of alpha3beta1 with mAbs resulted in induction of MMP-2 expression and secretion, whereas antibody ligation of alpha(v)beta3 led to down-regulation of MMP-9. The above data implicate integrins of proximal tubular epithelial cells in the regulation of MMPs and in the development of TBM thickening in diabetic nephropathy.     

Chemotherapie mit Cisplatin-Bleomycin und nachfolgende Strahlentherapie bei fortgeschrittenen Kopf-Hals-Tumoren

Summary 42 patients with advanced stage III and IV squamous cell carcinoma of the head and neck were treated with initial cisplatin and bleomycin chemotherapy and subsequent radiotherapy. 39 were evaluable for results, and 3 for toxicity only. 8 patients suffered from stage III and 31 from stage IV tumors, of these 10 with distant metastases. 5 patients underwent later a rescue operation. 27 were previously untreated (= group A) including 2 cases with localized relapses beyond the margins of surgical and/or radiotherapeutic treatment fields. 12 patients had a recurrence within pretreated areas (= group B). The induction chemotherapy alone showed the following results: In group A 4 (15%) CR, 10 (37%) PR, 7 (26%) MR; in group B 3 (25%) PR, 2 (17%) MR. The subsequent radiotherapy mostly consisted of a 65 Gy tumor dose given in 61/2 weeks. The results after completion of the combined modality therapy were: In group A 44% CR, 28% PR; in group B 10% CR and 30% PR. No patient resistant to the initial chemotherapy responded to the radiotherapy. The median survival time of stage III patients was 20 months but only 7 months in stage IV patients. 4 of all live with NED now between 30+ and 41+ months; 1 patient is alive with relapse. All the others are dead after a survival time of max. 32 months, included the 5 with rescue operation. In general, hematologic and renal toxicities were not severe, but nausea and vomiting were the worst tolerated side effects. 1 patient died from septic myocarditis having a WBC nadir of 2000/µl, probably due to additional immunologic deficiency because of inactive liver cirrhosis. The poor results concerning NED survival are discussed. We conclude, that an initial chemotherapy with CDDP and BLM gives good remission effects but its combination with radiotherapy at present fails to produce a NED survival benefit. Further efforts are necessary to improve the CR and the long time survivor rates.

Die Autoren danken folgenden Kollegen für ihre Mitarbeit: Drs. Garbea (HNO), B. Bienko, M. Danker, N. Birke, M. Klessing, K. Lottner, W. Palm     

Hypergammaglobulinemia and autoantibody induction mechanisms in viral infections

Polyclonal hypergammaglobulinemia is a characteristic of chronic inflammatory conditions, including persisting viral infections and autoimmune diseases. Here we have studied hypergammaglobulinemia in mice infected with lymphocytic choriomeningitis virus (LCMV), which induces nonspecific immunoglobulins as a result of switching natural IgM specificities to IgG. The process is dependent on help from CD4+ T cells that specifically recognize LCMV peptides presented by B cells on major histocompatibility complex class II molecules. Thus, hypergammaglobulinemia may arise when specific helper T cells recognize B cells that have processed viral antigens irrespective of the B cell receptor specificity. This nonspecific B cell activation may contribute to antibody-mediated autoimmunity.