Electrophysiological and biochemical characterization of a continuous human astrocytoma cell line with many properties of well-differentiated astrocytes

Astrocytes comprise about 25% of the cellular volume of the brain, and their main function is to maintain homeostasis of the neuronal environment. These cells are commonly identified on the basis of their membrane electrical properties and the presence of specific proteins. We have characterized the human astrocytoma cell line designated UC-11MG and have shown these cells have many of the traits of differentiated astrocytes. Many of the UC-11MG cells have a large resting membrane potential, averaging -74 mV. The slope of the Em vs log [K]o cuve was 58.5 mV per decade [K]o. The cells were inexcitable when exposed to brief depolarizing current pulses. The astrocytoma traits are virtually identical to those previously reported for normal astrocytes. The astrocytoma cells also express glutamine synthetase activity which is considered specific to astrocytes among brain cells. Previous work had also demonstrated the presence of other astrocyte markers glial fibrillary acidic protein and S-100 protein in the UC-11MG cells. The steady-state ion transport properties of Na+, Cl-, and K+ were also characterized in these cells, and the rates of efflux were found to be similar to those in other astrocytes, with the major difference being the presence of a second kinetic compartment in the UC-11MG cells. From this work, we conclude that the UC-11MG cell line displays prominent features associated with differentiated astrocytes, and may provide an excellent model system for the study of human astrocytes.     

Declining value of alanine aminotransferase in screening of blood donors to prevent posttransfusion hepatitis B and C virus infection. The Retrovirus Epidemiology Donor Study

BACKGROUND: Since the mid-1980s, blood banks in the United States have screened donors for elevated alanine aminotransferase (ALT) in an effort to prevent posttransfusion hepatitis. The present study was designed to quantitate the residual value of ALT screening following the implementation of hepatitis C virus (HCV) assays. STUDY DESIGN AND METHODS: Two approaches were used. First, a database of 2.3 million donations made by 586,507 volunteer blood donors between 1991 and 1993 was used to compare the incidence of seroconversion to hepatitis B virus (HBV) and HCV marker positivity in donors with elevated ALT values and with normal ALT values. Second, the duration of ALT elevation prior to HBV and HCV seroconversion was determined from 34 well-documented cases of posttransfusion HBV and HCV; elevated-ALT window periods were multiplied by rates of HBV and HCV incidence in donors to project the yield of ALT screening. Predictive value and cost- effectiveness analyses were also performed to compare the value of ALT screening before and after HCV screening was implemented. RESULTS: Both approaches indicate that ALT testing does not detect HBV in the window phase but does currently identify approximately 3 HCV window-phase donations per 1 million donations; this contrasts with ALT detection of approximately 1800 HCV-infectious units per 1 million donations prior to anti-HCV screening. Currently, only 8 in 10,000 donated units with elevated ALT (negative anti-HCV) are infected with HCV. The cost of continued ALT screening was estimated at $7,931,000 per quality- adjusted year of life saved. CONCLUSION: The yield, predictive value, and cost-effectiveness of ALT screening of blood donors have declined dramatically with the implementation of progressively improved anti-HCV assays. ALT screening of volunteer blood donors should be discontinued.     

Parvovirus B19 infection and Diamond-Blackfan anaemia

It is the purpose of the study to report the frequency of parvovirus in children with a diagnosis of Diamond-Blackfan anaemia and to discuss the possible aetiological role of parvovirus in Diamond-Blackfan anaemia. We found parvovirus DNA in 3 of 11 bone marrow smears. Giant pronormoblasts showed low sensitivity (33%) and poor specificity (75%). The presence of giant pronormoblasts was associated with a very high myeloid: erythroid ratio, and may not be specific for parvovirus infection, but a feature of severely suppressed erythropoiesis. The three parvovirus-positive patients were the only children who experienced a remission, and who are free of medication. The seven surviving parvovirus-negative patients are all currently on steroid treatment.     

KGF-transfected cells can stimulate growth and proliferation of human cultured keratinocytes in vitro

Objective: To establish two stably KGF-transfected, immortalized cell lines. Methods: HaCaT-keratinocytes and KMST-6-fibroblasts were transfected by liposome mediated gene transfer. Transfection effectivity, gene integration and configuration of the transgenic protein were investigated by ELISA, DANN-PCR and β-Gal-staining. Results: Most effective GF producing clones were tested by a colorimetric XTT-test. Conclusion: This is a significant acceleration of cell proliferation and mitosis of human keratinocytes in an Air Liquid Interface (ALI) test system.     

New dihydropyridine drug, nilvadipine, blocks the calcium slow action potential in rat-cultured aortic smooth muscle cells

The effects of the dihydropyridine analogs, nilvadipine (FR-34235) and mesudipine, on the electrical activity of rat aortic smooth muscle cells in culture (reaggregates) were compared with the calcium antagonist verapamil. Nilvadipine blocked the tetraethylammonium-induced action potentials (APs), whose inward current is carried almost exclusively by Ca2+ through voltage-dependent slow channels. The effects of nilvadipine were dose dependent, and nilvadipine had a more potent inhibitory effect on the K+-induced contraction than on the norepinephrine-induced contraction of rabbit aorta. The ED50 value for blockade of the K+-induced contracture by nilvadipine was 6.4 X 10(-8) M, and complete blockade of the Ca2+ slow channels occurred at 10(-8) M. Mesudipine also inhibited the Ca2+ slow channels in cultured vascular smooth muscle cells in a dose-dependent manner; elevation of the [Ca]O from 1.8 to 5.4 mM partially restored the slow APs. The order of the inhibitory action on the Ca2+-dependent slow APs was: nilvadipine greater than mesudipine greater than verapamil. The inhibition of Ca2+ influx during excitation by the drugs can account for their vasodilatory properties.