A subpopulation of bone marrow-derived macrophage-like cells shares a unique ion channel pattern with microglia.

Rat microglia share a number of antigenic, functional, and morphological similarities with macrophages from other tissues, but are characterized by a distinctly different pattern of ion channels in the cellular membrane (Kettenmann et al., J Neurosci Res 26:278-287, 1990). Macrophages typically express outward and inward K+ currents. In contrast, microglia lack outward currents and only show inwardly rectifying K+ currents, regardless of the isolation or cultivation method employed for microglia. In this study we demonstrate that a subpopulation of bone marrow-derived macrophage-like cells possesses inward rectifier K+ currents, but no outward currents and thus with regard to the electrophysiological characteristics closely resembles microglia. A second population of bone marrow-derived macrophage-like cells shows the usual channel pattern described for other body macrophages. Our results strengthen the hypothesis that in the bone marrow distinct pools of precursor cells exist, possibly reflecting an early differential lineage determination for body and brain macrophages, i.e., microglia.     

Detection of pneumococci in respiratory secretions: clinical evaluation of gentamicin blood agar.

The use of sheep blood agar containing 5 microng of gentamicin per ml has been suggested as a means of selectively isolating Streptococcus pneumoniae from respiratory secretions. We have tested this method, in parallel with standard methods, on 844 respiratory specimens in a clinical laboratory and have confirmed that the yield of pneumococci can be increased approximately 40% by using agar containing gentamicin. However, since the antibiotic suppresses the growth of staphylococci, group A streptococci, and gram-negative bacilli, gentamicin agar cannot be used as a replacement for the standard method. The requirement for duplicate plating raises the cost per additional pneumococcal isolate to prohibitive amounts. Although the method is useful in studies designed to isolate only pneumococci, it cannot be recommended for the routine clinical laboratory. An unanticipated observation from our study is that the yield of pneumococci in respiratory secretions can be increased 10-fold simply by screening sputum for the presence of leukocytes using the Gram stain. This is in agreement with results reported from other laboratories.     

Technische Ursachen der Resistenzminderung von Erythrocyten nach Vorbehandlung mit Dimethylsulfoxid

Zusammenfassung Es wurde nach der Ursache für die osmotische und mechanische Resistenzminderung DMSO-vorbehandelter Erythrocyten gesucht. Die systematische Modifikation des Inkubationsvorganges ergab, daß die Erythrocyten der Gefahr eines osmotischen Schocks ausgeliefert sind, sofern sie allzu rasch in ein DMSO-freies oder DMSO-armes physiologisches Medium überführt werden. Dies ist aber im Rahmen der osmotischen und mechanischen Resistanzbestimmung stets der Fall, so daß verständlich wird, daß DMSO-vorbehandelte Erythrocyten bei diesen Tests eine verstärkte Hämolyseneigung aufweisen müssen. Sie erklärt sich demnach durch technische Gegebenheiten, nicht aber durch toxische Eigenschaften des DMSO, und kann dadurch vermieden werden, daß die Erythrocyten langsam ins Kochsalzmilieu verbracht werden.

---

Summary The causes of the reduced resistence of DMSO-pretreated red cells were explored. A systematic modification of the incubation procedure showed that red cells treated with DMSO are in danger of osmotic shock, as far as they are suddenly transferred into physiologic media free from the protective agent. This is done, however, within the procedure for the determination of the osmotic/mechanical resistence, so that it can be understood easily why DMSO-pretreated red cells must show a reduced resistence in these tests. It is technical in nature, and not due to toxic properties of the substance. It can be avoided by slow transfer of the red cells into the salinic medium.

     

Update on epidemiology,diagnosis, and treatment of pertussis

AlthoughBordetella pertussis was identified as the causative organism of whooping cough in 1906 (1), numerous questions regarding epidemiology, diagnosis, treatment, and prevention of this disease remain unanswered. Widespread immunization has drastically reduced the prevalence of pertussis in many countries, but epidemics still occur, even in well-immunized communities (2, 3), which explains the continued interest in this old disease.This editorial will focus on some recent developments in the areas of epidemiology, diagnosis, and treatment of pertussis; it is not, however, intended as a comprehensive review of these fields.     

Supravitale Morphologische Veränderungen der Skelettmuskulatur in frühen Postmortalen Zeitintervalen

Current Medical Science - Die morphologischen Veränderungen des mechanisch bzw. Elektrisch gereizten Skelettmuskels von 20 Leichen mit erhaltener supravitaler Reagibilitat in...     

Human biomonitoring of polychlorinated biphenyls in 130 exposed elementary school children

In the classroom air on a primary school polychlorinated biphenyls were present in a wide range extending to 10.220 ng/cbm; in a side room even 19.550 ng/cbm were measured. The school was closed down, a flame retardant paint was detected to be the main source of this contamination. 130 differently exposed persons gave blood specimens for measurement of PCB concentrations. Compared with a comparative reference collective of equal age reported by the analysing laboratory, the PCB blood concentrations of 92 actual pupils were even lower. A comparison with five near-representative child collectives of South Germany did not show any obvious difference. The reference values of the German Human Biomonitoring Commission were exceeded by 4 of 92 pupils for PCB 138, by 6 pupils for PCB 153 and by 6 pupils for PCB 180. In a group of 9 teachers and 1 cleaning person the median values of reference collectives of equal age reported by the analysing laboratory were exceeded by 8 persons for PCB 138, 7 persons for PCB 153 and 8 persons for PCB 180. The 95. Percentiles of these reference collectives and the reference values of the German Human Biomonitoring Commission were not exceeded. In bivariate and multiple regression analyses the data of 92 actual pupils showed positive associations between blood levels of PCB and age as well as nursing period, a negative association between PCB blood concentrations and body-mass index and a weak influence by gender (boys had lower blood concentrations). In addition, the results of multiple regression analyses showed (with the exception of the analyses of PCB 180 without controlling for gender) a significant influence of PCB concentrations in indoor air on PCB blood concentrations. This association could not be detected in bivariate analyses, and in comparison to the mentioned main influence variables it was obviously weaker. But basing on the results of the multiple regression analyses one can calculate an increase of PCB blood concentration by 3% multiplicatively if PCB indoor concentrations increase by 1000 ng/cbm.