Demonstration der Plaqueentwicklung bei multipler Sklerose mittels Magnetisation-Transfer-Ratio-Bildern und Protonenspektroskopie mit kurzer Echozeit

Zusammenfassung Wir untersuchten eine Patientin mit sekund?r progressiver multipler Sklerose w?hrend eines akuten Schubes und im Verlauf nach 6 Monaten mit verschiedenen Magnetresonanztechniken. In der konventionellen Bildgebung fand sich zeitgleich zur klinischen Verschlechterung eine ausgedehnte kontrastmittelanreichernde L?sion. Mittels der Protonenspektroskopie und Magnetisation-Transfer-Bildern konnten heterogene pathologische Ver?nderungen mit wahrscheinlich ?demat?sen Gewebever?nderungen in der Peripherie und Demyelinisierung im Zentrum der L?sion in der akuten Phase dargestellt werden. Mit dem Abklingen der akuten Symptomatik zeigte sich eine Rückbildung der akut entzündlichen Aktivit?t und eine Erholung der MR-Gewebeparameter. Im Vergleich zur konventionellen Magnetresonanztomographie bieten Magnetisation Transfer Bildgebung und Protonen Spektroskopie spezifischere Informationen bei der Darstellung pathologischer Gewebever?nderungen der multiplen Sklerose.      

Spontaneous voltage and current fluctuations in tissue cultured mouse dorsal root ganglion cells

Fetal mouse dorsal root ganglion (DRG) neurons were maintained in primary dissociated cell culture for periods of 7 days to 3 months. Intracellular recordings from these cells revealed the presence of spontaneous subthreshold potentials in 101/177 neurons studied. When measured at the resting membrane potential, these spontaneous voltage events took two forms: (a) high frequency potential fluctuations several millivolts in peak-to-peak amplitude and (b) small, discrete hyperpolarizations. Neurons exhibiting either type of event were designated as 'active' DRG cells. No spontaneous potentials were seen in DRG cells hyperpolarized to membrane voltages more negative than -64 +/- 11.5 mV (n = 5 cells). Under voltage-clamp conditions, the subthreshold potentials of active DRG cells were replaced by fluctuations in outward current. The power spectral density, S(f) of these current fluctuations was approximated by an equation of the form S(f) = (S(o)/[1 + (f/fc) alpha] where 2 less than or equal to a less than or equal to 3 and the half-power frequency fc = 11.3 +/- 3.1 Hz at 23 degrees C (n = 17 cells). The spontaneous voltage fluctuations of active DRG cells were abolished in Ca2+-free saline, and of the divalent metal cations Sr2+, Mg2+, Ba2+, Co2+ and Mn2+, only Sr2+ could substitute for Ca2+ in the maintenance of this activity. Tetraethylammonium ions (1-10 mM) reversibly blocked the spontaneous potentials, while caffeine (10 mM) increased the frequency of these events. The spontaneous voltage fluctuations were not dependent on the presence of spinal cord neurons in the culture plate, and they were also observed in cultured DRG cells derived from adult mice.     

A heterochromatic homogeneously staining region (HSR) in the karyotype of a human breast carcinoma cell line

A long heterochromatic region is described in the karyotype of a human breast carcinoma cell line. Cytochemical studies of this region suggest: 1) homogeneously staining regions (HSRs) in human tumor cells may show some heterogeneity in staining, 2) HSRs in human tumor cells may be euchromatic or heterochromatic by C-, G-, and Q-banding methods.     

The photosensitized grafting of N-vinyl-2-pyrrolidone on cotton using anthraquinone reactive dyes

The photosensitized grafting of N-vinyl-2-pyrrolidone on cotton has been successfully carried out over a range of pH values, monomer concentrations and for various concentrations of dye-sensitizer. Grafting is shown to be critically dependent on each of these factors. Evidence is presented which suggests that the dye is only physically held by the substrate which in turn indicates that grafting occurs via a hydrogen abstraction process. The physical nature of the graft copolymer (cellulose-co-N-vinyl-2-pyrrolidone) is shown through electron micrographs. Reflectance spectroscopy provides an insight into the part played by the dye-sensitizer in the grafting reaction.     

Hepatitis-Associated Markers in the American Red Cross Volunteer Blood Donor Population

Abstract. The American Red Cross collects blood from a number of defined subsets of the donor population and the proportion of blood collected from each subset varies widely from center to center. A large part of the variation in prevalence of HBsAg may be related to variations in the proportion of blood collected from plants and factories, military units and schools or colleges. We have derived a regression equation, significant at the p<0.001 level, which links HBsAg prevalence with these collection parameters. Using this equation, we were able to predict the prevalence of HBsAg among first-time donors in 6 of the 9 geographic divisions of the United States with an accuracy exceeding 10%. The predictions for the remaining divisions were within 35% of the actual value. Correlation studies were supported by measurements of true donor prevalence in three blood centers.     

Abortive phage-infection and UV-protection markers on Col I plasmids from epidemic strains of Salmonella

Cultures of Escherichia coli carrying ColI plasmids received in conjugation from strains of Salmonella typhimurium and S. agona were examined for abortive infection (Abi) of phage BF23 and for enhanced resistance to the lethal action of UV-irradiation (Uvr). The Abi character of stored cultures of E. coli was also compared with the reaction of the same stock culture tested 5 years before. Seven of the eight potential types differentiated by three characters were represented among 160 ColI plasmids: ColIa Abi+ Uvr+ (3 plasmids), ColIa Abi- Uvr+ (1), ColIa Abi- Uvr- (2), ColIb Abi+ Uvr+ (85), ColIb Abi+ Uvr- (5), ColIb Abi- Uvr+ (4), ColIb abi- Uvr- (60). Recognition that different plasmid types could be carried by strains of a clone proved useful in the interpretation of the epidemic spread of strains of S. typhimurium of phage type/biotype 141/9f in Scotland and in tracing the ancestry of a recently emerged rhamnose non-fermenting mutant strain of S. agona.     

Steady-state bioavailability of two clorazepate dipotassium dosage forms.

A specially designed tablet dosage form of the benzodiazepine clorazepate dipotassium (Tranxene) was developed for once-a-day administration. The drug was administered at a dose of 22.5 mg as (1) the tablet, (2) three 7.5 mg capsules, or (3) one 7.5-mg capsule given every 6 hours. Peak serum levels from the tablet were intermediate between those of the single- and divided-dose capsule regimens. The desired decrease in magnitude of peak levels was obtained without affecting the extent of absorption. Pharmacokinetic analysis of the data according to a two-compartment open model with first-order absorption indicated that the serum half-life (t0.5beta) of nordiazepam, the major biotransformation product present in serum, was about 48 hours and served as a basis for the design of a multiple-dose steady-state study. Multiple-dose administration of the tablet and divided-capsule regimen to two groups of subjects for ten days indicated each dosage form yielded similar minimum steady-state serum levels of about 0.6 micrograms/ml which plateaued following seven days of drug administration. The dosage forms were crossed over between the groups on day 11 and administered for an additional four days. The minimum serum levels obtained with the tablet and capsule were not statistically different. Additionally, the peak serum level and area under the curve (pi=24 hours) at steady state were equivalent between the dosage forms. Good agreement was obtained between model-predicted and observed serum levels during multiple-dose administration for both the tablet and capsule regimens. The serum half-life of nordiazepam following 14 days of clorazepate dipotassium administration was similar to that found after a single dose. These results indicate that a single daily dose of drug as the tablet produced serum levels equivalent to a divided-capsule regimen.