BAEE esterase (kallikrein-like) activity in parotid saliva of normal rats and rats with various forms of experimental hypertension (genuine, renovascular and DOCA salt hypertension)

A technique for continuous and quantitative collection of parotid saliva including salivary flow rate determination for in vitro experiments in rats is described. Kallikrein-like activity in parotid saliva of rats with various forms of arterial hypertension (genuine, renovascular and DOCA salt hypertension) was studied. Kallikrein-like excretion was measured by its estoerolytic activity using benzoyl arginine ethyl ester (BAEE) as a substrate. The levels of kallikrein-like activity in parotid saliva of normotensive control rats ranged between 2.5 and 4.0 mU/min during salivary flow stimulation with pilocarpine. In all forms of experimental hypertension kallikrein-like activity in saliva was increased two-to fourfold. This increase was not related to the activity of the renin-angiotensin system.

Über Biosynthese und Struktur des tierischen Melanins

Bei der Biosynthese des Melanins wird Dopa nicht als Ganzes in Melanin eingebaut, sondern ein von Atom zu Atom verschiedener Prozentsatz wird vorher abgespalten. Durch Versuche mit radioaktivem Dopa, das gleichzeitig mit Tritium und 14C markiert war, wurde die Einbauwahrscheinlichkeit der einzelnen H- und C-Atome des Dopa gemessen. Als Bezugspunkt diente die Einbauwahrscheinlichkeit des α-C-Atoms, die gleich 1 gesetzt wurde. Folgende Einbauwahrscheinlichkeiten wurden gemessen: H-α 0,51; H-β 0,43; H-2 0,46; H-5 0,26; H-6 0,49; C-Carboxyl 0,64.

Die gemessenen Einbauwahrscheinlichkeiten deuten darauf hin, daß Dopa im Gegensatz zu den bisherigen Vorstellungen nicht ausschließlich durch Polymerisation von 5.6-Indochinon aufgebaut wird, sondern daß es in großem Umfang Polymer-Einheiten enthält, in denen die Carboxyl-Gruppe und das H-Atom in 6-Stellung des Dopa noch vorkommen. Auf Grund der Einbauwahrscheinlichkeiten wurde eine neue Strukturformel des Melanins vorgeschlagen.

Pilot study for comparison of reticulocyte-micronulei with lymphocyte-micronuclei in human biomonitoring

Biomonitoring tries to determine the consequences for humans of exposures to environmental or pharmaceutical agents. Different end points have been employed to assess the burden of genomic damage. This is the first report comparing a recently introduced new end point, the reticulocyte-micronuclei analyzed by flow cytometry with the widely used lymphocyte-micronucleus assay, applied to two exposure scenarios leading to enhanced genomic damage. Radioiodine therapy was chosen to represent a short time exposure and hemodialysis treatment in end-stage renal failure was chosen to represent a chronic exposure. The results show that iodine radiation induced measurable genomic damage in the lymphocyte-micronucleus assay as well as in the reticulocyte-micronucleus test. Of two groups of patients under hemodialysis treatment, a reduced genomic damage was found with the lymphocyte-micronucleus test, but not with the reticulocyte-micronucleus test in the group undergoing daily hemodialysis, which removes uremic toxins more efficiently as compared to conventional hemodialysis, the treatment applied in the other group. The limited life-span of reticulocytes may make them less suitable for accumulation of chronic low level damage than lymphocytes. In conclusion, the lymphocyte-micronucleus test may be applicable to more exposure situations (including low chronic exposure), but the reticulocyte-micronucleus assay may be easier to perform in a clinical setting. The latter reflects a more rapid reduction of genomic damage after an acute exposure.

Cross-species amplification from crop soybean Glycine max provides informative microsatellite markers for the study of inbreeding wild relatives

The development of microsatellite markers through transfer of primers from related species (cross-species amplification) remains a little-explored alternative to the de novo method in plants. In this study of 100 microsatellite loci from Glycine max, we examined two aspects of primer transfer. First, we tested if source locus properties can predict primer transfer and polymorphism in Glycine cyrtoloba and Glycine clandestina. We transferred 23 primers to G. cyrtoloba and 42 to G. clandestina, with 19 loci polymorphic within G. clandestina. However, we could not predict transfer or polymorphism from the source locus properties. Second, we evaluated the subset of 11 polymorphic loci for study in G. clandestina populations representing two local morphotypes. All loci were informative within populations (population mean He +/- SE = 0.58 +/- 0.04). We directly sequenced 28 alleles at 4 representative loci. The allelic patterns and sequencing results established that 8 of 11 loci were typical microsatellites, confirming the utility of primer transfer as an alternative to de novo development. Additionally, we found that morphotypic differentiation between populations was paralleled by changes in polymorphism level at six loci and size homoplasy at one locus. We interpret these patterns as being a product of selfing in G. clandestina. Our results demonstrate the value of allele sequence knowledge for the most effective use of microsatellites.

[Medical-surgical intuition and professional policy]

Many decisions in business and policy are made intuitively. According to scientific studies intuitive persons do not belong to a certain social group; they are unconventional, self-confident and self-reliant. In professional policy facts established by documentary evidence and legally guaranteed are the basis for decisions. Facts are dealing with the past. In order to consider the future and to react in situations of immediate interest intuitive abilities are just as important. (The appropriate argument at the right time at the right place). Beside the "Leitlinien" in surgical therapy the "Methodenfreiheit", which is connected to intuitive thinking, must be lasting.

[The status of perioperative pain therapy in Germany. Results of a representative, anonymous survey of 1,000 surgical clinic. Pain Study Group]

To evaluate the status of perioperative pain management we mailed a anonymous postal survey to all 2,254 surgical departments in Germany. We received answers from 1,000 clinics (44.4%) which were representative related to their regional distribution. We asked the responsible surgeons to report their organizational structure and responsibilities for treating pain patients, the significance of the problem, their methods of measuring pain, and the usage of different analgesic drugs and methods. In 47% the surgeon and the anesthesist together had responsibility for adequate postoperative pain treatment; in 33% and 14%, respectively, it was the surgeon and anesthesist alone. Only 41% knew the interdisciplinary statement on pain therapy of the Professional Societies of German Surgeons and Anaesthesists from 1992. Although the importance of postoperative pain is globally acknowledged, only 19.1% of all departments had a written concept for pain treatment. Pain was measured in only 11% of the clinics mainly by using the visual analogue scale. Most surgeons relieve pain solely with systemic drugs. Regional analgesia was used by 18% only 51% of the surgeons decide on the choice and dosage of analgesic therapy on the ward; 33% admit that pain therapy often starts after complaints of the patient. 70% of all surgeons never participated in a congress on pain. We conclude that postoperative pain management in most German surgical departments still lacks effectiveness, adequacy, and organizational and scientific background.

Use of the recursion formula of the Gompertz function for the quantitation of PCR-amplified templates

One common drawback of the currently used procedures to quantitate the polymerase chain reaction (PCR) is that the statistical evaluation of the experimental data depends on many, not just trivial, model assumptions. In the present study we report on an improvement in this crucial step of the quantitative PCR. The experimental design underlying the introduced method is exactly the same as in the case of the so-called PCR. However, by applying growth curve analysis based on the recursion formula of the Gompertz function the kinetics of the accumulation of the amplicon are estimated conjointly from data spanning both the and phases of the reaction. We demonstrate the method by determining the relative number of templates (a 206 bp segment spanning the exon 3 of the X-chromosomal murine Hprt-gene) contained in known orders of dilutions of DNA isolated from the spleen of the C57BL/6J-mouse. [32P]-dATP incorporation was used in duplicate experiments to quantify the amplicons as a function of amplification cycles. Our results: i) indicate that the accumulation of the PCR product as a function of PCR cycles follows a sigmoidal pattern compatible with the Gompertz growth model (P<0.0000001); ii) directly support the thesis that the kinetical pattern of accumulation of amplicons of a given DNA fragment does not depend on the number of corresponding DNA templates provided to the reaction; iii) permit a simple direct evaluation of the parallelity in the course of the accumulation of amplicons from different template numbers as a function of amplification cycles, which is a silent preposition in the evaluation of the so-called PCR; iv) allow an easy quantitation of the relative number of provided templates.

Improved determination of variant erythrocytes at the glycophorin A (GPA) locus and variant frequency in patients treated with radioiodine for thyroid cancer

Red blood cells from individuals with the blood group MN express each form of the allelic GPA protein (GPAM and GPAN) on their cell surface. Variant cells have lost one form of the protein. Their frequency is about 10(-5) in blood from unexposed persons. The BR6 assay is currently the most widely used assay to determine variant frequency (VF) by immunolabelling and flow cytometry. The precision of the BR6 assay is mainly limited by the Poisson error because only small numbers of variant cells are detected in each assay. The BR6 assay has been improved by magnetic cell separation (MACS) of variant erythrocytes prior to their determination by this assay. This new version of the assay is named 'MACS-BR6'. It allows enumeration of variant cells from 2 x 10(8) or more blood cells instead of 5 x 10(6) in the BR6 assay with a precision which is about 5 times higher than that of the BR6 assay. The MACS-BR6 assay was used to determine the VF of GPAN/0 and GPAN/N variant cells in 12 healthy adults and 11 patients treated with radioiodine for thyroid cancer 2 to 16 years before. The average red bone marrow dose was 347 mGy. In healthy adults the mean VF of GPAN/0 and GPAN/N variant cells was 16.1 x 10(6) and 5.3 x 10(-6) respectively. In patients the corresponding mean VF was 25.4 x 10(6) and 11.9 x 10(-6), respectively. The patients GPAN/0 VF was significantly higher than that of controls. In patients VF increases linearly with the dose. The linear regression parameters of VF were 16.6 x 10(-6) (intercept), 23.7 x 10(-6) GY-1 (slope) and 6.3 x 10(-6) (intercept), 12.9 x 10(-6) Gy-1 (slope) for GPAN/0 and GPAN/N variant cells, respectively.

The chicken lysozyme gene 5′ MAR and the Drosophila histone SAR are electroelutable from encapsulated and digested nuclei

Cultured chicken cells were encapsulated in agarose microbeads, lysed in a near-physiological buffer and resulting encapsulated nuclei were digested with a restriction enzyme and electroeluted. After removal of approximately 97% of the chromatin, the nuclear lamina, residual nucleoli and an internal nuclear network remained. The majority of nascent RNA was also recovered in digested and electroeluted nuclei. Surprisingly, however, the chicken lysozyme gene 5′ MAR was quantitatively electroeluted from digested nuclei of expressing and non-expressing cells, as well as the promoter region and the coding sequence. When encapsulated nuclei were digested partially, the proportion of elutable 5′ MAR chromatin was comparable to that of elutable bulk chromatin. Furthermore, after digestion of encapsulated nuclei from Drosophila Kc cells, the histone SAR was electroeluted to the same extent as bulk chromatin. We conclude that the lysozyme gene 5′ MAR and the histone SAR are not permanently attached to a nuclear matrix or scaffold.

Age dependent selection against HPRT deficient T lymphocytes in the HPRT+/- heterozygous mouse

The fraction of HPRT deficient T lymphocytes was measured in the HPRT +/- female mouse between birth and an age of about 2 years. The animals were the F1 offspring of the HPRT deficient strain 129MF1 and HPRT competent C57BL/6J-mice. T lymphocytes from spleen were cloned in vitro and HPRT deficient clones were detected by double-labeling with [3H]thymidine and [14C]hypoxanthine. During the first weeks of life the fraction of deficient lymphocytes sharply decreases from about 50% at birth to 10-30% at an age of 10 weeks. In adult animals the fraction of HPRT deficient T cells smoothly further decreases to values about 10% at 80-90 weeks. The equation gamma(t)=[0.547 x exp(-0.405 x t)] + [0.453 x exp(-0.0116 x t)] was found to be a good approximation of the time course of HPRT deficient cells in spleen; gamma(t) is the fraction of deficient cells per competent cell and t is the age of animals in weeks. It is postulated that the selection against HPRT deficient T lymphocytes is the consequence of the reduced proliferative capacity of HPRT deficient cells (=selection factor). The time course of the ratio of deficient cells can be described as a function of the proliferation rate of the HPRT competent T cells and this selection factor. The sharp initial decrease is explained by a high selection pressure against HPRT deficient cells in young animals when the proliferation rate of the expanding T cell population is high and when T cells proliferate in the bone marrow. In adult animals the selection pressure against HPRT deficient cells is reduced, since T cells arise in general in peripheral lymphatic organs, where the salvage pathway is of lesser importance compared to the de novo purine synthesis. Implications of the selection against HPRT deficient lymphocytes for the widely used HPRT mutation assay are discussed.

[Liability in consultation of physicians from different specialties from the physician's viewpoint]

The limitations of each specialty are laid down in the rules for continuing education for physicians. The necessary cooperation between the surgeon and the anesthesiologist is discussed on the example of the polytraumatized patient and the pain therapy after surgery. All rights and duties of the emergency team have to be laid down by the hospital management. The medical responsibilities for the therapeutic actions are on the side of the specialists.

Mutant frequency at the H-2K class 1 and HPRT genes in T lymphocytes from the X-ray-exposed mouse

The frequency of H-2Kk and HPRT-deficient T cells was measured in the H-2Kb, kDd,k genotype mouse 8-10 weeks after X-ray exposure at doses up to 6 Gy to compare the mutant frequency (MF) of an autosomal gene with that of an X-chromosomal gene. H-2K mutants were enriched by magnetic cell separation (MACS) using the H-2Kk-specific monoclonal antibody H100.5/28 and were isolated by limiting dilution cloning. Finally, the mutant phenotype was verified by flow cytometric analysis in a representative number of clones. The frequency of HPRT-deficient T cells rises from 2.5 x 10(-6) at 0 Gy to a maximum of 1.13 x 10(-4) at 4 Gy, and decreases to 2.9 x 10(-5) at 6 Gy. The H-2K- MF in the non-irradiated mouse was 8.4 x 10(-7). It increases with dose to a maximum of 8.1 x 10(-6) at 4 Gy and declines to 3.3 x 10(-6) at 6 Gy. The H-2K- MF measured depends on the monoclonal antibody used for the isolation of mutants. In a pilot study with another H-2Kk-specific monoclonal antibody (11.4.1), the spontaneous MF was four times higher than in experiments with the H100.5/28 monoclonal antibody. The expression of other class 1 antigens was investigated in H-2K- clones. The H-2Dd antigen had also disappeared in six of 41 clones from irradiated animals. This gene is situated at a distance of 1500 kb from the K-locus. The H-2Kb antigen was present in every investigated clone. In the discussion a model is presented that explains the shape of the dose-response curve of MF by selection against mutants in vivo systems under homeostasis. The results of the present investigation indicate that observed X-ray mutagenicity depends on many factors and that several genes have to be explored before reliable risk estimates are possible.

[Ambulatory surgery--definition, socioeconomic and legal aspects]

One of the most important intentions of GSG 1992 is the favourization of traditional ambulatory surgery by legislative measures. However in general surgery a much higher potential for a significant reduction in cases of classical hospitalization and thus concomitant substantial financial savings lies in short-stay eg. one-day/one-night procedures. At present methods of laparoscopic cholecystectomy, thyroid surgery and herniorrhaphy-together about 50% of common hospital patients-are developed enough to be practiced safely under this strategy. In the future further suitable techniques could evolve from minor access surgical concepts.

[Characterization of 24-hour survival rate and duration of survival of hydroxyethyl starch cryopreserved erythrocytes after autologous transfusion in the dog]

BACKGROUND

Cryopreservation of erythrocytes using hydroxyethyl starch (HES) as cryoprotecting additive could result in a nearly unlimited storage stability of preserved red cells. In addition, it would allow its immediate use for transfusion. In order to assess the therapeutic efficacy of erythrocytes cryopreserved with HES, their 24-hour post-transfusion survival and long-term survival was evaluated.

MATERIALS AND METHODS

The experiments were carried out with dog erythrocytes as an animal model for human erythrocytes. To each of 6 German shepherd dogs a 15-ml sample of erythrocyte suspension, labeled with 51Cr (25 microCi) after thawing, was autologously injected. Caused by hemolysis 29% of the formerly cryopreserved erythrocytes have not been labeled. To each of 6 control animals 15 ml of a suspension of freshly drawn and 51Cr-labeled erythrocytes was injected. The 51Cr radioactivity in later taken blood samples was a measure for the number of injected erythrocytes having remained in the circulation until the moment of blood withdrawal. The effect of cryopreservation was assessed by comparison of the test group with the control group.

RESULTS

In both groups 30% of the applied cells left the circulation within 30 min. This was effected by pharmacological enlargement of the dogs' spleen and not by hemolysis of the erythrocytes. After the first 24 h all of the cryopreserved labeled erythrocytes had survived to the same amount (> 95%) as the labeled fresh red cells. Between 12 h and 20 days after injection, in both groups the 51Cr activity decreased exponentially by 4.8 and 4.5%/d. This difference was not significant. The area under the curve amounted to 1253 and 1257% d, respectively.

CONCLUSIONS

There exists a subpopulation of red cells that is destroyed by freezing stress. As a result the freed stroma would be a serious transfusion risk. All erythrocytes having survived the cryopreservation procedure resemble the fresh erythrocytes with regard to the in-vivo survival; their therapeutic efficacy is not impaired. In the context of in-vitro results with human erythrocytes it can be expected that at the present developmental state of the cryopreservation procedure at least 93% of the human erythrocytes cryopreserved with HES have a normal 24-hour and long-term post-transfusion survival.

Dose and dose-rate dependence of the frequency of HPRT deficient T lymphocytes in the spleen of the 137Cs gamma-irradiated mouse

The frequency of hypoxanthine phosphoribosyl transferase (HPRT) deficient splenic T lymphocytes was measured in the 137Cs gamma-irradiated mouse by the T cell cloning method. Doses from 0.3 to 6 Gy were applied at the dose-rates 0.5 Gy/min, 1 Gy/day and 1 Gy/week. Mutants were determined 8-10 and 30-40 weeks after the end of exposure. Radiation-induced mutant frequency (MFi) was calculated by subtracting the age corrected spontaneous mutant frequency (MFsp) from total mutant frequency (MF) found in irradiated animals. Data were fitted to linear and linear-quadratic dose-response models. MFi depended markedly on dose, dose-rate and time after exposure. When mutants were determined 8-10 weeks after acute irradiation (0.5 Gy/min) the dose-effect curve fitted the linear-quadratic equation MFi = 6.9 x 10(-6) Gy + 1.2 x 10(-6) Gy2, whereas in low dose-rate experiments (1 Gy/day, 1 Gy/week) the dose-effect curves were linear. The slope of the linear regression was about 3 x 10(-6). When low dose-rate-irradiated animals were killed 30-40 weeks after irradiation, MFi was about one-third of that observed after 8 weeks. The dose dose-rate effectiveness factor (DDREF) for radiation mutagenicity was calculated in animals that had been exposed 8-10 weeks previously. For doses < 2 Gy the reduction in effectiveness was about 1.5 when the irradiation dose-rate was < or = 1 Gy/day. For higher doses DDREF was 3-5.

[The effect of combolen on the erythrocyte distribution in the dog]

The effect of Combolen (3.9 mg/kg bw s.c.) on the distribution of erythrocytes in dogs was investigated. After application of Combolen, the hematocrit of the animals decreased exponentially within 1 h by 21%. The reversal of the reduction began from 2 h after the time of application, amounting to 4% within the first day and finishing by the fourth day. After injection of 51Cr-labelled erythrocytes, radioactivity in the circulation of Combolen-treated dogs decreased exponentially within 2 h by at least 30%. It was concluded that the dog's spleen, under physiological conditions, contains about 10% of the animal's blood. The time-courses of the decrease of hematocrit and radioactivity in the circulation were found to be very similar. In accordance with this observation, a high correlation (r = 0.97) between the level of radioactivity after injection of radio-labelled erythrocytes and the corresponding hematocrit values after application of Combolen was found. After application of erythrocytes, labelled with 99mTc, an extensive distribution from the circulation into the spleen was observed by scintigraphy. This process can be understood by using a closed-compartment model. An equation, based on this model, describes the observed time course of the hematocrit values, as well as the number of 51Cr-labelled erythrocytes, in Combolen-treated dog. Presumably, the observed effect of Combolen is the result of the relaxation of the smooth muscle cells in the trabeculae of the spleen, caused by central-nervous depression of sympathetic tone. Combolen seems to be a suitable tool in pre-clinical testing of a novel blood preserve with dog as a test animal. Its potent ability to eliminate erythrocytes from circulation is distinguishable from the sequestration of damaged red cells. Furthermore, its ability to prevent the spleen from uncontrolled hematocrit modulating actions in addition to its sedative effects is considered to be an invaluable advantage.

Isolation and quantification of class 1 MHC gene mutants in mouse T cells by immunoselection with a magnetic cell sorter (MACS)

A method is described for determining the frequency of cells with a mutation in an autosomal gene coding for a membrane protein. Using a monoclonal antibody to H-2Kk surface antigen and magnetic cell separation (MACS) more than 10(4)-fold enrichment of the H-2Kk negative population was achieved, as tested with artificial mixtures containing a known number of antigen-negative cells. After a second magnetic sorting mutant frequencies as low as 10(-6) could be measured. The number of clonogenic mutants was evaluated by limiting dilution cloning and verification of the mutant phenotype by FACScan (flow cytometry) analysis in a representative number of clones. The spontaneous frequency of H-2Kk deficient mutants was 0.80 x 10(-6), and this increased after irradiation with 6 Gy X rays to 3.38 x 10(-6) within the next 8 weeks. About 50 mutant clones were screened for the presence of other class 1 antigens on the cell surface by FACScan analysis. All mutants continued to express other class 1 antigens.

Arthroscopy of the knee without pathological findings

From 1983 to 1990, 82 knee arthroscopies (8.2%) carried out in our patients found nothing pathological. Sixty-four percent of these patients were active in sports, but trauma was noted in 32% of the cases only. Football and other ball games, skiing, and track and field athletics were the main causes. Twenty-six percent of the patients had undergone previous surgery in the affected knee. At a mean of 4.6 years postoperatively, clinical and radiological re-assessment was conducted so as to compare our pre- and intraoperative findings with the further course of events. We found that 48.2% of the patients were symptom-free after the diagnostic arthroscopy, 37.5% had persistent discomfort and 14.3% had a recurrence of discomfort after 6 months to 2 years. The objective measurement score (Zarins Rowe score), at 47.5 out of 50 points, was better than the subjective score, at 40 out of 50 points. Our diagnoses had to be changed retrospectively: meniscal lesions were diagnosed too frequently, while chondropathia patellae and instability were often missed. Additionally, complaints could be related to abnormal axis, limited range of motion of the hip or knee, leg length inequality and hypermobility. Being unable to verify a presumed intra-articular lesion arthroscopically is frustrating for both doctor and patient. Our data suggest that meniscal signs should be looked at more critically and emphasise the need for a complete evaluation of the whole locomotor system.

Charakterisierung der 24-Stunden-Überlebensrate und Lebensdauer von mittels Hydroxyethylstärke kryokonservierten Erythrozyten nach autologer Transfusion im Hund

<i>Hintergrund:</i> Die Kryokonservierung von Erythrozyten unter Verwendung von Hydroxyethylstärke (HES) als Gefrierschutzadditiv würde die nahezu unbegrenzte Haltbarkeit eines Erythrozytenkonzentrates, verbunden mit seiner sofortigen Ver-fügbarkeit nach Auftauen, ermöglichen. Zur Beurteilung der therapeutischen Wer-tigkeit solcher Erythrozyten wurde ihre In-vivo-24-Stunden-Überlebensrate und Lebensdauer am Modell Hundeerythrozyt charakterisiert. <i>Material und Methodik:</i> Sechs Schäferhunde erhielten je 15 ml kryokonservierte und nach dem Auftauen mit ⁵¹Cr (25 µCi) markierte Erythrozyten. Sechs Kontrolltiere erhielten Cr-markierte Nativerythrozyten. Wegen Hämolyse nach dem Auftauen gelangten 29% der kryokonservierten Erythrozyten nicht zur Markierung. Zu definierten Zeitpunkten wurden den Tieren Blutproben entnommen und darin die ⁵¹Cr-Radioaktivität als Maß für die Zahl der bis zum Zeitpunkt der Probenentnahme in der Zirkulation verbliebenen Erythrozyten gemessen. Beurteilungsgrundlage für die Wirkung der Kryokonservierung war der Vergleich der Verumgruppe mit der Nativgruppe. <i>Ergebnisse:</i> Alle markierten kryokonservierten Erythrozyten überlebten die ersten 24 Stunden in vergleichbarer Rate ( > 95%) wie die markierten Nativerythrozyten. Dabei verließen in den ersten 30 min aus verteilungskinetischen Gründen 30% der applizierten Zellen die Zirkulation. Zwischen 12 h und 20 Tagen nahm die ⁵¹Cr-Aktivität bei beiden Versuchsgruppen exponentiell um etwa 4,8 bzw. 4,5%/Tag ab. Der Unterschied war nicht signifikant. Das Impuls-Zeit-Integral für diesen Zeitraum betrug 1253 bzw. 1257% Tage. <i>Schlußfolgerungen:</i> Es existiert eine Erythrozyten-Subpopulation, die durch den Frier/Tau-Prozeß zur Lyse gebracht wird und durch ihr stromahaltiges Hämoglobin ein ernstes Transfusionshindernis darstellen könnte. Alle die Kryokonservierung mit HES überlebenden Erythrozyten gleichen in ihrer Lebensdauer den Nativerythrozyten, ihre therapeutische Wertigkeit ist nicht eingeschränkt. Zusammen mit In-vitro-Befunden an Humanerythrozyten lassen die Ergebnisse erwarten, daß beim

Rapid alterations in cAMP accumulation in brain nuclei of rats following microinjections of vasoactive intestinal polypeptide (VIP) into the lateral ventricle

The in vivo effect of exogenous vasoactive intestinal polypeptide (VIP) on the accumulation of cAMP in 21 microdissected brain nuclei was investigated 3 and 7 min after intraventricular injections in rats. VIP elicited significant (up to 20-fold) increases in cAMP levels. This effect is region specific varying considerably among the brain regions investigated. VIP dramatically increased the cAMP content of the lateral septal nucleus, several hypothalamic nuclei, the habenula, the midbrain central gray and the locus coeruleus. Smaller increases were observed elsewhere including some VIP-rich brain areas such as the cerebral cortex and the hippocampus.

A simple mechanical procedure to produce encapsulated cells

Images

Normal and reverse dose-rate effect for the induction of mutants in somatic cells by ionizing radiation

In radiobiology the reduction of the dose-rate in general diminishes the degree of the biological effect per unit dose. This phenomenon is characterized by the dose-rate effectiveness factor (DREF). DREF is the factor by which a risk per unit dose obtained from data at high dose and high dose-rate overestimates the risk at low doses and/or low dose-rates. In general, DREF is in the range of 2 to 10. In the first part of this review, a short survey of the modern microdosimetric approach for a better understanding of radiation load on the cellular level and the significance of dose-rate is given. Experiments on the influence of dose-rate on the mutagenicity of ionizing radiation in cultured cells are reviewed. In contrast to other biological effects, in most experiments the reduction of the dose-rate had no or even a reverse dose-rate effect (DREF < or = 1). In the second part results on the influence of dose-rates on the induction of HGPRT-deficient T-lymphocytes in mice irradiated in vivo are given. Mutagenicity decreases with dose-rate and DREF values between 3-10 were measured. Possible reasons for the discrepancy between in vitro and in vivo experiments are discussed.