Antiplatelet Drugs Plus Thrombolysis in Myocardial Infarction

A breakthrough in platelet inhibition was achieved with the advent of antagonists of the glycoprotein (GP) IIb/IIIa receptors. These receptors are essential to platelet aggregation triggered by any of several different mechanisms. GP IIb/IIIa receptor antagonists, especially the monoclonal antibody abciximab, have been established as adjuncts to angioplasty in acute coronary syndromes. Conjunctive treatment with thrombolysis in myocardial infarction has been studied less extensively. GP IIb/IIIa receptor antagonists appear to be a feasible adjunct to thrombolysis. In particular, the use of abciximab in conjunction with reduced doses of thrombolytics is an attractive approach to achieve early coronary reperfusion with probably acceptable bleeding risk. The eventual role of this combined treatment can only be defined by the large-scale clinical trials that will be performed in the near future.     

Syncytial organization of acanthors of Polymorphus minutus (Palaeacanthocephala), Neoechinorhynchusrutili (Eoacanthocephala), and Moniliformis moniliformis (Archiacanthocephala) (Acanthocephala)

The fine structures of immature and of developed shelled acanthors of three species belonging to the three subgroups of the Acanthocephala were investigated. Acanthors are surrounded by four eggshells (embryonic envelopes) and are composed of three syncytia: a frontal syncytium, a central syncytium, and an epidermal syncytium. Neither a sense organ nor a nervous system has been found. The central syncytium shows a mass of condensed nuclei and 12 decondensed nuclei and gives rise to 10 anterior/posterior subepidermal myofibrillar systems and 2 oblique retractor muscles. Circular muscles are missing. A single decondensed nucleus can be assigned to each of the 12 muscular systems. The epidermal syncytium embeds the other two syncytia and forms the wrinkled epidermis, which shows an extracellular glycocalyx and intrasyncytial condensations. Prominent recurved hooks, which mark the anterior end of each acanthor, and body spines are intraepidermal differentiations. Partly branched tubular infoldings of the epidermal plasma membrane of the acanthor exist and represent precursors of the pore ducts typical of the adult epidermis. Autapomorphies in the ground pattern of the monophylum Acanthocephala are the four eggshells, the early development of three syncytia, the condensed nuclei in the central syncytium, and the differentiation of ten longitudinal muscle bands and two muscle retractors and of intraepidermal hooks and spines. The syncytial organization of the epidermis with intraepidermal skeletal condensations and infoldings of the apical plasma membrane are characteristics inherited from a stem species common to Acanthocephala, Seison, and Rotifera. Received: 25 September 1996 / Accepted: 10 October 1996     

Flexible versus rigid endoscopes for outpatient hysteroscopy: a prospective randomized clinical trial

To evaluate patient acceptance, optical properties and the clinical feasibility of flexible compared with rigid hysteroscopes, 142 patients undergoing outpatient hysteroscopy were included in a prospective, randomized clinical trial. The flexible hysteroscope was used in 70 patients, and the rigid instrument in 72. At different stages of the hysteroscopy the level of pain experienced by the women was assessed using a 10 cm visual analogue scale. Optical properties characterized by the parameters intrauterine visibility, hysteroscopic view and diagnostic accuracy were ranked by the surgeons using a 5-point scale (1 = excellent to 5 = insufficient), and duration of the hysteroscopy was measured. Hysteroscopy was successful in 87.5 and 100% of patients in the flexible and rigid groups respectively. With the use of rigid telescopes, discomfort at introduction and during the hysteroscopy was significantly greater (median 1.7 versus 0.7, P = 0.003; 3.1 versus 1.2, P < 0.001 respectively), but optical properties were judged to be far superior (P < 0.001 for all three comparisons) and procedure time was significantly shorter (median 70 versus 120 s, P = 0.003). In conclusion, outpatient hysteroscopy seems to be less painful when using flexible telescopes. However, rigid hysteroscopes provide superior optical qualities and permit a more rapid performance with higher success rates at much lower cost.     

Polarized ion transport during migration of transformed Madin-Darby canine kidney cells

Epithelial cells lose their usual polarization during carcinogenesis. Although most malignant tumours are of epithelial origin little is known about ion channels in carcinoma cells. Previously, we observed that migration of transformed Madin-Darby canine kidney (MDCK-F) cells depended on oscillating K⁺ channel activity. In the present study we examined whether periodic K⁺ channel activity may cause changes of cell volume, and whether K⁺ channel activity is distributed in a uniform way in MDCK-F cells. After determining the average volume of MDCK-F cells (2013±270 m³; n=8) by means of atomic force microscopy we deduced volume changes by calculating the K⁺ efflux during bursts of K⁺ channel activity. Therefore, we measured the membrane conductance of MDCK-F cells which periodically rose by 22.3±2.5 nS from a resting level of 6.5±1.4 nS (n=12), and we measured the membrane potential which hyperpolarized in parallel from –35.4±1.2 mV to –71.6±1.8 mV (n=11). The distribution of K⁺ channel activity was assessed by locally superfusing the front or rear end of migrating MDCK-F cells with the K⁺ channel blocker charybdotoxin (CTX). Only exposure of the rear end to CTX inhibited migration providing evidence for horizontal polarization of K⁺ channel activity in transformed MDCK-F cells. This is in contrast to the vertical polarization in parent MDCK cells. We propose that the asymmetrical distribution of K⁺ channel activity is a prerequisite for migration of MDCK-F cells.     

Endogenous brain angiotensin II disrupts passive avoidance behavior in rats

The presence of angiotensinogen, the precursor of angiotensin II (ANG II), in brain tissue and in cerebrospinal fluid (CSF) allows stimulation of endogenous brain ANG II by renin. Passive avoidance tests were performed in female Wistar rats. The animals received an electrical shock after entering a black box on the first experimental day. Avoidance was tested every 24 h for 5 consecutive days. Renin in doses of 0.01 and 0.1 units was injected once into the lateral brain ventricles 2 min before the first test. CSF ANG II increased from 40 to 4547 and 5152 fmol per ml (means), respectively. A dose-dependent disruption of avoidance learning was observed, the frequency to enter the black box increasing from 11% (control) to 29% and 46%, and the latency decreasing from 165 (control) to 143 and 116 sec, respectively. These effects were statistically significant (P less than 0.001) for more than 24 h and returned to control levels after 48 to 120 h. Administration of the converting-enzyme inhibitor SQ 14225 i.v.t. prior to renin injections abolished the renin effects. Injections of renin given 22 h after learning were without effect.     

Effect of marrow on the high frequency ultrasonic properties of cancellous bone

A number of investigators have performed in vitro measurements of cancellous bone to determine how various ultrasonic parameters depend on bone density and trabecular orientation. To facilitate handling and storage of bone specimens, the marrow is often removed prior to ultrasonic measurements. However, the assumption that marrow does not affect ultrasonic measurements at high frequencies (>1 MHz) has not been tested. The goal of this study is to determine the effect of marrow on the ultrasonic properties of bovine cancellous bone at frequencies greater than 1 MHz. Twelve specimens of cancellous bone were obtained from the proximal end of four bovine tibia. Ultrasonic measurements consisting of normalized broadband ultrasonic attenuation (nBUA), speed of sound (SOS) and apparent integrated backscatter (AIB) were measured in each specimen using 2.25 MHz (centre frequency) broadband ultrasonic pulses. These measurements were performed before and after marrow removal either along the superoinferior (SI) or mediolateral (ML) direction. SOS and nBUA showed no significant difference (p > 0.05) for either direction of propagation after marrow removal. AIB showed no significant difference in the SI direction. For the ML direction, a small but statistically significant difference (p = 0.044) was observed after marrow removal.     

Quantitative histologic studies of the gonads of sand rats (Psammomys obesus) during the development of diabetes mellitus]

Quantitative-histological investigations (point counting method) are pointed out in 27 male and 15 female sand rats. The animals are divided in the IGT (impaired glucose tolerance), the diabetic and the control group. The LEYDIG cells are in the IGT-group increased, and in the diabetic group decreased. The female sand rats are characterized by the tendency of increase of size and number of follicles in the IGT-group. Corpora lutea are reduced but atretic follicles are increased in the diabetic group. The ovaries are greater in diabetic sand rats.     

Protective role of endothelial nitric oxide synthase

Nitric oxide is a versatile molecule, with its actions ranging from haemodynamic regulation to anti-proliferative effects on vascular smooth muscle cells. Nitric oxide is produced by the nitric oxide synthases, endothelial NOS (eNOS), neural NOS (nNOS), and inducible NOS (iNOS). Constitutively expressed eNOS produces low concentrations of NO, which is necessary for a good endothelial function and integrity. Endothelial derived NO is often seen as a protective agent in a variety of diseases.This review will focus on the potential protective role of eNOS. We will discuss recent data derived from studies in eNOS knockout mice and other experimental models. Furthermore, the role of eNOS in human diseases is described and possible therapeutic intervention strategies will be discussed.     

Induction of chromosome aberrations and mitotic arrest by cytomegalovirus in human cells

Human cytomegalovirus (CMV) is potentially an effective but often overlooked genotoxic agent in humans. We report here evidence that indicates that infection by CMV can induce chromosome alterations and mitotic inhibition. The frequency of chromosome aberrations induced was dependent on the input multiplicity of infection (m.o.i.) for human lung fibroblasts (LU), but not for human peripheral blood lymphocytes (PBLs) when both cell types were infected at the GO phase of the cell cycle. The aberrations induced by CMV were mostly chromatid breaks and chromosome pulverizations that resembled prematurely condensed S-phase chromatin. Pulverized chromosomes were not observed in LU cells infected with virus stocks that had been rendered nonlytic by UV-irradiation at 24,000 ergs/mm2 or from infection of human lymphocytes. In LU cells infected with UV-irradiated CMV, the frequency of aberrations induced was inversely dependent on the extent of the exposure of the CMV stock to the UV-light. In permissive CMV infection of proliferating LU cells at 24 hr after subculture, a high percentage (greater than 40%) of the metaphase cells were arrested at their first metaphase and displayed severely condensed chromosomes when harvested 48 hr later. A significant increase (p less than 0.05) in the chromosome aberration frequency was also observed. Our study shows that CMV infection is genotoxic to host cells. The types and extent of damage are dependent on the viral genome expression and on the cell cycle stage of the cells at the time of infection. The possible mechanisms for induction of chromosome damage by CMV are discussed.