Growth-related order of the retinal fiber layer in goldfish

The retinal fiber layer and the juxtaretinal portion of the optic nerve of goldfish have been studied with light and electron microscopy in order to determine whether the age-related order of fibers in the nerve originates in the retina. In the retina, no patent spaces (channels) were noted. The fibers ran in fascicles and consisted of two classes: nonmyelinated fibers, which ran superficially (close to the vitreal surface), and "myelinated" fibers, which ran more deeply and were loosely wrapped by processes presumed to be glial. The myelinated fibers were larger and presumably older. The nonmyelinated fibers are believed to be the young ones, from the peripheral, more recently generated, ganglion cells, for the following reasons. (1) Their size and cytoskeletal elements were typical of young axons. (2) They were the only axons in peripheral retina. (3) They were continuous with the nonmyelinated fibers in the nerve, previously shown to be the young ones. (4) When retinal axons were cut peripherally, the degenerating axons were in the superficial part of the fiber layer. (5) Growth cones, presumably from the newest ganglion cells, were always observed at the most superficial position in the fiber layer, in direct contact with the basal lamina of the inner limiting membrane superficially and nonmyelinated fibers deeply. The nonmyelinated fibers always clustered together in the retinal fiber layer and occupied the most central portion in the cross-section of the optic nerve head. Thus, the age-related organization of fibers in the nerve is established in the retina. These results are discussed in the context of growth, with the aim of evaluating the relative importance of four factors that might influence the intraretinal course of the growth cone. Its interactions with other fibers and with the basal lamina of the inner limiting membrane seem to be more important than interactions with the glial end feet or guidance into open, preformed channels.     

Comparison of RFLP-DR beta and serological HLA-DR typing in 1500 individuals

A group of 1522 individuals were HLA-DR-typed both by the standard serological technique and by the RFLP method. Whereas 11% (n = 164) of the serological typings were technically unsuccessful or doubtful, all typings were successful by RFLP. The results of the remaining 1358 typings revealed a serological error rate of 25%. In 16% a serological "blank" turned out to be a definable allele by RFLP, while in 9% an allele was incorrectly interpreted by serology. Of the individuals tested, 11% were HLA-DR homozygous by RFLP. Our results demonstrate an important clinical potential of RFLP typing for the typing of bone marrow transplant candidates in whom serology often fails, and for kidney transplant candidates with "blanks" or serologically "difficult" HLA antigens.     

Characterization of recast Nafion films by small- and wide-angle X-ray scattering

Room temperature recast Nafion

1 General formula:

films, prepared under different humidities in the curing atmosphere, were characterized by small- and wide-angle X-ray scattering (SAXS and WAXS). SAXS reveals that the humidity influences the size of the ionic clusters in these polymer films. It was found that the number and size of ionic clusters increases with increasing relative humidity. WAXS indicates the presence of locally ordered regions of the backbone polymer. These results allow a qualitative understanding of the electrochemical behaviour of Nafion recast films cured at different humidities, as described in the literature.     

Der Wert der Duplexsonographie nach der orthotopen Lebertransplantation Erfahrungen an 44 Patienten

Zusammenfassung In einer prospektiven Untersuchung wurde an 44 Patienten (33 Männer, 11 Frauen) riach einer elektiven orthotopen Lebertransplantation die Duplexsonographie 196ma1 angewendet. Ziel der Untersuchung war es festzustellen, inwieweit and in welchem zeitlichen Zusammenhang sich die Parameter pulsatiler FluBindex (PFI) und Dämpfungsindex (DI) bei Komplikationen wie Abstoung und Cholangitis verändern. Der Duplex-Doppler-Ultraschall wurde im Mittel 5mal pro Patient durchgeführt. Die letzte Sonographie erfolgte am Entlassungstag. Bei den Messungen fiber der Leberarterie, der Pfortader und den Lebervenen wurden jeweils der PFI und der DI bestimmt. Die Ergebnisse der Indexuntersuchungen wurden mit dem klinischen Verlauf (Abstoung, Cholangitis) sowie mit den Resultaten von 88 Biopsiepräparaten der Lebertransplantate in Beziehung gesetzt. Bezüglich einer histologisch gesicherten AbstoBung ergab der PFI (über der Leberarterie gemessen) eine Sensitivität von 69,4 % and eine Spezifitdt von 72,2 %, der DI (über den Lebervenen gemessen) eine Sensitivität von 89,4% und eine Spezifitdt von 89,1 %. Wenn auch die einfach und beliebig oft anwendbare Untersuchungstechnik die bioptische Sicherung einer Rejektion nicht ersetzen kann, so ist sie in hohem Mae in der Lage, Indikationen zur Biopsie frühzeitig stellen zu lassen und ein Ansprechen auf eine Therapie kurzfristig und mit holier Genauigkeit anzuzeigen.

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Duplex sonography after orthotopic liver transplantation: findings in 44 patients

In a prospective study, 44 patients (11 women, 33 men) who had received orthotopic liver transplants underwent a total of 196 consecutive duplex Doppler ultrasound examinations. The aim of the study was to evaluate the correlation between the pulsatile flow index (PFI) and the damping index (DI) as far as complications as rejection or cholangitis were concerned. The patients were examined five times each on average. The PFI and DI were measured in the hepatic artery, the portal vein and the hepatic veins. The findings were compared with the clinical course (cholangitis, rejection) and the histomorphological diagnosis as determined in biopsy specimens. In biopsy-proven rejection episodes, the sensitivity of the PFI in the hepatic artery was 69.4%, the specificity 72.2%. The sensitivity of the DI in the hepatic vein was 89.4%, the specificity 89.1 %. Combining the two, specificity was more than 90%. PFI and DI in the portal vein bore no apparent relation to clinical course or histomorphological diagnosis. We found duplex Doppler ultrasound extremely beneficial in determining the timing and indication for liver biopsy. In addition, this simple examination, which can be performed as often as desired, accurately shows the transplanted liver's response to measures taken to counter rejection.

     

Consequences of haemostasis disorders on anaesthestic management

New molecular markers of coagulation and fibrinolysis activation have been developed and used to identify patient subgroups that frequently develop increased procoagulant turnover and, hence, disseminated intravascular coagulation and organ dysfunction. The idea of inhibiting the coagulation hyperactivation by the administration of antithrombin has led to experimental findings that pinpoint an anti-inflammatory action of antithrombin. Preliminary clinical trials of high-dose antithrombin administration in sepsis are promising. Point-of-care coagulation testing remains controversial since a variety of perioperative therapeutic regimens such as aprotinin administration obviously do not require 'on-line' coagulation monitoring.     

Smoking behaviour and compensation: a review of the literature

Rationale: Compensation or compensatory smoking, accurately defined, deals with the question of whether switching to cigarette brands with different smoke yields is associated with a change in smoke uptake proportional to the change in machine-derived yields. The issue of compensation is important because it bears on whether switching to ”lighter” brands means lower overall smoke intake or not. Objectives: The present review investigated whether and to what extend low yield cigarettes are smoked more intensively. In addition, published data on whether nicotine, ”tar”, or any other smoke constituent or property influence compensational smoking are summarized. Methods: The studies on compensation were classified as follows: (1) studies on smoking behaviour in relation to cigarette yields (with and without brand switching); (2) studies on compensation for nicotine (switching between cigarettes which differ ”only” in their nicotine yield, nicotine supplementation, manipulation of renal nicotine excretion, administration of nicotine agonists or antagonists); (3) studies on compensation for other factors (influence of tar, taste, irritation, draw resistance). In order to quantify the degree of compensation, an index is defined and applied to selected brand switching studies. This compensation index determines, in relative units, the degree to which a smoker responds to a change in smoke yields with a change in smoke uptake measured by suitable biomarkers. The role of vent blocking is also briefly discussed. Results: Most of the studies which compare the smoking behaviour when smoking cigarettes with different smoke yields supply evidence for ”partial” compensation, suggesting that cigarettes with lower yields are smoked more intensively than those with higher yields. These studies also show that a change in the daily number of cigarettes is not a common mechanism of compensation. Effective vent blocking during smoking is a rare event and can therefore also be regarded as an uncommon mechanism of compensation. Evaluation of a suitable subset of brand-switching studies revealed an average compensation of 50–60% of the nicotine yield. Compensation tended to be more complete when changing to cigarettes with higher yields than when changing to cigarettes with lower yields. In general, brand-switching studies do not supply information on the underlying causal factors responsible for compensatory smoking. Results of the nicotine supplementation studies are not conclusive: some report evidence of nicotine titration, others do not. A general problem with this type of investigation is that continuous nicotine application does not mimic the spike-wise application with cigarette smoking, and may lead to nicotine tolerance. There is limited evidence that cigarettes were smoked more intensively when the urinary clearance of nicotine was increased. A small number of studies provide some evidence that smoking intensity increased after smokers were administered a nicotine antagonist. Several reports indicate that tar, taste and sensory properties of the smoke as well as the draw resistance of the cigarette may play a role in compensatory smoking. Low-yield cigarettes usually have reduced pressure drops which smoke researchers have suggested leads to increased puff volume. This effect seems to be independent of the smoke yield of the cigarette. There is also some evidence that some smokers maintain a consistent pattern of smoking which works independent of any changes in nicotine or tar yields, taste or design features of the cigarette (”functional autonomy”). Conclusions: The available data suggest that smokers partially compensate for a different smoke yield. While the factors and their interaction responsible for compensational smoking are not fully understood, there are data suggesting that a subgroup of smokers may partially compensate for nicotine. Even in this subgroup of smokers, however, the relative importance of the pharmacological versus the sensory effects of nicotine in smoke remains to be determined. Received: 4 January 1999 / Final version: 22 March 1999