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Biomedical subjects

J Seifert

Publications and source records attributed to J Seifert.

At least 55 records · Page 3Linked to original sources

Use of standardized SCID-hu Thy/Liv mouse model for preclinical efficacy testing of anti-human immunodeficiency virus type 1 compounds.

We have developed standardized procedures and practices for infection of SCID-hu Thy/Liv mice with human immunodeficiency virus type 1 for the prophylactic administration of antiviral compounds and for evaluation of the antiviral effect in vivo. Endpoint analyses included quantitation of viral load by intracellular p24 enzyme-linked immunosorbent assay, DNA PCR for the presence of proviral genomes, flow cytometry to measure the representation of CD4+ and CD8+ cells, and cocultivation for the isolation of virus. Efficacy tests in this model are demonstrated with the nucleoside analogs zidovudine and dideoxyinosine and with the nonnucleoside reverse transcriptase inhibitor nevirapine. This small-animal model should be particularly useful in the preclinical prioritization of lead compounds within a common chemical class, in the evaluation of alternative in vivo dosing regimens, and in the determination of appropriate combination therapy in vivo.

Animals↗

[Local excision of rectal carcinoma].

From January 1985 till December 1994 109 patients with rectal carcinoma were treated by local excision, in 36 patients a radical operation was performed afterwards. In the assessment of tumor infiltration endosonography was superior to rectal-digital examination. In 34 patients with local excised "low risk" T1-carcinomas and tumor free margins no local recurrence was observed. Two of ten patients with local excised "low risk" T1-carcinoma and no adequate margin of healthy tissue developed a local recurrence. Regarding our results the local excision of "low risk" T1-carcinomas seems justified, if final histological workup reveals an adequate margin of healthy tissue.

Adult↗

[Rare case of isolated trapezius fracture].

This is a report of a rare case of an isolated fracture of the trapezium. Origin, diagnosis, differential diagnosis, treatment and complications are evaluated and described.

Adult↗

The influence of age and particle number on absorption of polystyrene particles from the rat gut.

The bioavailability of polystyrene particles (1 microns) labelled with FITC (3M Company, Düsseldorf) was tested in rats after enteral administration. Since macromolecules and particles are preferentially transported in the lymph, the number of particles was counted in the lymph of the thoracic duct over a 6 h period. Uptake in young rats (6-8 wk) was compared with that in 5 and 9 mo animals. Young animals absorbed only 87 particles whereas a marked increase in the uptake of particles was observed in 5 mo animals (up to 775) but there was a decrease to 518 particles in older animals (9 mo). This number of particles is the total number of the entire output of the thoracic duct lymph over a 6 h period. In individual animals this number showed a considerable fluctuation over time. The volume of the collected lymph fluid was relatively constant (3.5 +/- 0.5 ml) in all animals. The bioavailability of the particles in the lymph was also influenced by the applied dose of particles. After intraduodenal administration of 3.7 x 10(5) particles only 18 particles could be found in the lymph. Increasing the dose to 3.7 x 10(7) particles raised the number of particles in the lymph to 116. The highest dose of 3.7 x 10(9) was correlated with the greatest absorption, 775 particles being found in the lymph. The uptake of particles from the gut thus depends on different factors including the age of the animal and the number of applied particles.

Aging↗

Influence of immunoglobulin and interleukin 2 on the translocation of microorganisms from gut into blood.

The aim of this study was to influence the translocation of microorganisms and endotoxin from the gut of septic rats by the intravenous (i.v.) administration of immunoglobulin and interleukin 2. Acute infection was induced in all animals by an intraperitoneal bacterial challenge of 2 x 10(6) microorganisms (Ps. aeruginosa, E. coli, Kleb. pneumoniae). Immediately after the bacterial challenge control animals were given albumin i.v. whereas the experimental groups were given immunoglobulin or interleukin 2. A significant reduction of bacteria in the plasma of rats was observed in immunoglobulin treated animals (10,000 CFU/ml vs 450 CFU/ml). This was accompanied by an increase of plasma endotoxin of nearly 100% within the first 2 h. Interleukin 2 essentially did not change the bacterial count in comparison with albumin-treated control animals but reduced the endotoxin level in plasma up to tenfold. It is concluded that both immunoglobulins and interleukin 2 are involved in severe infections. Whereas immunoglobulins reduce bacterial translocation, interleukin 2 stimulates the elimination of endotoxin.

Animals↗

Immunotherapy in liver tumors: III. A new experimental model of metastatic liver tumors from colorectal carcinoma for cytokine therapy.

A new model of metastatic liver tumors in Wistar/Furth rats is introduced. A colorectal adenocarcinoma cell line (LDLX40) induced by 1,2-dimethylhydrazine was injected through one of the branches of the ileal mesenteric vein to develop metastatic liver tumors in rats. On day 30 after the inoculation of tumor cells, micrometastases were detected under microscopy in all animals that received tumor inoculation. Macrometastases in 87.7% of animals were found by either the tumor staining test or ultrasonography. No extrahepatic tumor developed in this tumor model. To observe the effects of different treatment strategies on metastatic liver tumors, 35 animals were randomly divided into four groups. Group I served as control. Group II underwent hepatic artery ligation (HAL). Group III received intraportal administration of recombinant interleukin-2 (rIL-2) and interferon-alpha (IFN-alpha). Group IV had intraportal medication of rIL-2 and IFN-alpha + HAL (the IIH protocol). Results indicated that rapid tumor growth was seen in the control tumors. HAL produced little response to metastatic liver tumors as compared to the control group (P > 0.05). The combined application of rIL-2 and IFN-alpha showed an improved result, with 22% of tumor growth inhibition or regression (P < 0.05 compared to the control group). Twenty-eight percent of tumor growth restraint or regression was found in the group treated with the IIH protocol (P < 0.05 compared to the control group). We conclude that this new experimental model of metastatic liver tumors is reproducible, and that the IIH protocol is effective in the treatment of metastatic liver tumors in rats. These beneficial effects from the IIH protocol may be introduced into patients with metastatic liver tumors.

Adenocarcinoma↗

Immunotherapy in liver tumours: I. Combined administration of recombinant interleukin-2 (IL-2) and interferon-alpha through the subcutaneous transposed spleen prolongs the half-life of IL-2 in vivo and enhances antitumor effects.

Two modifications in this study, including the use of subcutaneous transposed spleen (STS) as a port for administration of recombinant interleukin-2 (IL-2) and interferon-alpha (IFN-alpha), and the mixture of IL-2 and IFN-alpha with degradable starch microspheres (IIM), for the treatment of rat liver tumor are introduced. Group I is the control. Group II received the IIM schedule through the STS. Group III and group IV received IL-2 and IFN-alpha, diluted with normal saline and injected through the STS or a peripheral vein. The comparative studies indicated that the best result was seen in group II where the elevated concentration of IL-2 in portal blood and massive tumor necrosis with lysis were observed. Inhibitions of tumor growth of 33%, 20% and 13% in group II, III, and IV, respectively, were observed. We conclude that administration of the IIM schedule through the STS is an effective method for the treatment of liver tumor in rats.

Animals↗

Immunotherapy in liver tumors: II. Intratumoral injection with activated tumor-infiltrating lymphocytes, intrasplenic administration of recombinant interleukin-2 and interferon alpha causes tumor regression and lysis.

This study tested the effect of intratumoral injection with activated tumor-infiltrating lymphocytes (TIL), and simultaneous administration of recombinant interleukin-2 (rIL-2) and interferon alpha (IFN-alpha) (LII protocol), on mouse liver tumor. Group I (n = 10) served as the controls. Group II (n = 17) received rIL-2 + IFN-alpha schedule. Group III (n = 20) received the LII protocol. A total of 5 x 10(6) of TIL were injected into 4 sites of a tumor in a single treatment. rIL-2 (1 x 10(6) IU) on the first day and IFN-alpha (1 x 10(5) IU) on the second day were alternately given with a total of 10 treatment doses that were completed in 20 days. Tumor remission or regression rates of 29% and 40% were obtained in groups II and III, respectively, but no remission was obtained in the controls. A large number of TIL were also observed in the tumors treated with the LII protocol. Making comparisons between the control group and IL-2 + IFN-alpha schedule, and the control group and LII protocol, the ratios of cytolytic activity of TIL in vitro were 0:32 and 0:57, respectively. We conclude that the LII protocol appears to be more effective in the treatment of mouse liver tumor than the IL-2 + IFN-alpha schedule, and that it may be a new promise for the treatment of patients with liver malignancies.

Animals↗

Effects of trifluoromethylaniline isomers on enzyme activities in lymphatic organs and hematology of the rat.

Three isomers of trifluoromethylaniline (TFMA) were investigated for their possible different toxic effects on the hematopoietic system in male Wistar rats. The effects of isomeric 2-, 3- and 4-TFMA were compared with those of aniline, the prototypic drug. Strong leukocytosis manifested by considerable increase in the number of all respective white blood elements was observed in the peripheral blood 1 day after the administration of 4-TFMA. In contrast, erythropoiesis, as ascertained by erythrocyte count and hemoglobin concentration, was inhibited by 4-TFMA. The determination of the ED50 revealed lymphocytes to be the most responsive elements towards 4-TFMA administration. Besides hyperemic and proliferative splenomegaly the histological changes in maturation of immunocompetent cells following the 4-TFMA administration were found also in thymus. In accord with an enhanced incorporation of [3H]thymidine, the specific activity of thymidine kinase (TdK) in spleen was increased after a single dose of 4-TFMA. Activities of the catabolic enzymes adenosine deaminase (ADA) and inosine phosphorylase (IP) decreased in both organs with the exception of IP activity in thymus. The effects evoked by the 3-TFMA isomer were regularly less pronounced, and 2-TFMA was nearly inactive.

Adenosine Deaminase↗

Transplantation of spleen cells in patients with hemophilia A. A report of 20 cases.

It has been reported that coagulation factor VIII (F. VIII) is produced in the spleen and other organs. Transplantation of splenic whole organ and spleen cells may, therefore, be used to treat patients with hemophilia A. The donor spleen from brain-dead donors was used to prepare spleen cell suspension for transplantation. Twenty-two spleen cell transplantations were performed on 20 patients suffering from severe hemophilia A at our institutes. Two of them underwent a second infusion of spleen cells since there was no increase in plasma F. VIII activity after the first transplantation. All but two patients showed a marked clinical improvement. Increased plasma F. VIII activity was observed in 18 of 20 cases. The peak plasma F. VIII activity in these recipients rose to 10%-15% posttransplantation in 14 cases and to over 15% in 4 cases from pretransplant levels of 0%-3%. Generally, the elevation of plasma F. VIII activity could be detected 4-7 days following transplantation of spleen cells and this lasted from 22 to 58 weeks. Four patients whose peak plasma F. VIII activity was greater than 15% experienced an uneventful course after transplantation. The patients with plasma F. VIII activity over 10% showed less frequent bleeding and prolonged intervals between bleed as well as improvement in hemophilic arthrosis. Two patients who had interval hematuria before transplantation did not have any relapse for up to 2 years after infusion of the spleen cells. These results indicate that spleen cell transplantation may be a promising method for the management of patients with hemophilia A.

Adolescent↗

Solubilization of neuropathy target esterase and other phenyl valerate carboxylesterases from chicken embryonic brain by phospholipase A2.

Membrane-bound neuropathy target esterase (NTE) and associated phenyl valerate carboxylesterases were solubilized from chicken embryo brain by phospholipase A2. Phospholipase A2 from bee or cobra (Naja) venoms were the most effective preparations in solubilizing brain NTE and other phenyl valerate carboxylesterases. Phospholipase C and several proteinases (endoproteinase, pronase E, proteinase K, thermolysin, trypsin) did not solubilize brain membrane-bound carboxylesterases but reduced their activity. NTE solubilization by phospholipase A2 did not affect its apparent Km and Vmax for the substrate phenyl valerate or the susceptibility of phenyl valerate carboxylesterases to inhibition by paraoxon and mipafox. NTE thermal stability diminished after the treatment of brain membrane fragments with phospholipase A2.

Animals↗

Trifluoromethylanilines--their effect on DNA synthesis and proliferative activity in parenchymal organs of rats.

Reactive isomeric 3- and 4-trifluoromethylanilines (3-,4-TFMA), and control aniline itself, induced the following effects on biosynthesis of DNA in the liver, kidney, thymus and spleen of rats: (a) The administration of 4-TFMA initially suppressed the utilization of labeled thymidine for splenic DNA synthesis during the early prereplicative stage. However, with progressing time the incorporation of the labeled marker began to increase and in 30 h its level exceeded the controls by more than 200%. As expected, aniline administration resulted in mild depression of incorporation during the whole period studied. (b) 4-TFMA caused a significant increase of incorporation of labeled thymidine into DNA thymine also in the thymus. After administration of aniline the utilization of labeled thymidine for the synthesis of DNA thymine in thymus was suppressed during the first 16 h. (c) The dose-response curve showed a linear increase of incorporation in the spleen within the dose range between 0.125 and 0.500 mmol/kg of 4-TFMA. (d) It appears that enhanced incorporation of labeled thymidine into splenic and thymic DNA is a phenomenon specific for compounds bearing the CF3 group on the 4-position of the phenyl ring, such as 4-TFMA and 4-TFMPD. On the contrary, the analogous 3-CF3 substituted derivatives had no effect. Increased incorporation of labeled thymidine into spleen and thymus DNA apparently represents an increased DNA synthesis and cellular proliferation in lymphatic organs. The proliferative response was possibly evoked by the preceding hemolysis or by other toxic effects caused by the drug.

Aniline Compounds↗

Structural requirements for altering the L-tryptophan metabolism in mice by organophosphorous and methylcarbamate insecticides.

This study defined structural requirements for organophosphorous and methylcarbamate insecticides for altering the L-kynurenine pathway of L-tryptophan metabolism in mice. Kynurenine formamidase inhibition by organophosphorous acid triesters and methylcarbamates is the proposed primary event resulting in increase in xanthurenic acid urinary excretion and plasma L-kynurenine. Alteration of the L-kynurenine pathway occurred with compounds that inhibited liver kynurenine formamidase by more than 80%. Pyrimidinyl phosphorothioates followed by crotonamide phosphates were the most potent compounds that changed L-tryptophan metabolism, i.e., pirimiphos-ethyl (20 mg/kg) inhibited liver kynurenine formamidase by 99%, and increased xanthurenic acid urinary excretion and plasma L-kynurenine by 576 +/- 195 and 330 +/- 44%, respectively. Replacement of sulphur by oxygen in the phosphorothioate diazinon reduced in vivo liver kynurenine formamidase inhibition. Consequently, xanthurenic acid urinary excretion and plasma L-kynurenine were not elevated. Atropine, cycloheximide, 2-PAM and phenylmethylsulfonyl fluoride did not alleviate diazinon-altered L-tryptophan metabolism. Because of the potential of the majority of organophosphorous acid triesters and methylcarbamates to inhibit kynurenine formamidase, this novel noncholinergic mechanism warrants consideration in assessment of organophosphorous and methylcarbamate toxicity in occupational and accidental exposures.

Animals↗

Assay of tryptophan 2,3-dioxygenase using liver slices and high-performance liquid chromatography.

Liver tryptophan 2,3-dioxygenase (TDO) activity was determined by high-performance liquid chromatography. The enzyme activity was expressed as the sum of N-formyl-L-kynurenine (FK) and L-kynurenine (KYN) produced from L-tryptophan (TRY) by liver slices. FK and KYN were detected spectrophotometrically at 254 nm after their separation on a reversed-phase C18 column. KYN formation proceeded according to zero-order kinetics for at least 4 h with 15 mM TRY at 37 degrees C. The apparent Michaelis constant was 1.2 mM TRY with a maximum velocity of 59 pmol min-1 mg-1 wet weight. The method was applied for TDO assay in mice treated with the organophosphorus acid triester diazinon. Kynurenine formamidase inhibition by diazinon resulted in reduced KYN formation, FK accumulation, and moderate TDO increase.

Animals↗

Alteration of mice L-tryptophan metabolism by the organophosphorous acid triester diazinon.

Diazinon [O,O-diethyl O-(2-isopropyl-6-methyl-4- pyrimidinyl)phosphorothioate] altered the formation of several L-tryptophan metabolites associated with the L-kynurenine pathway in mice. Liver kynurenine formamidase was inhibited almost completely by diazinon (10 mg/kg). The enzyme inhibition resulted in reduced L-kynurenine biosynthesis in livers with a concomitant accumulation of N-formyl-L-kynurenine. In contrast to the liver, plasma L-kynurenine increased up to 5-fold in diazinon-treated mice. Consequently, the urinary excretion of xanthurenic acid and kynurenic acid was raised 5- to 15-fold. The revelation of this novel mechanism of diazinon action is an important piece of information needed for a better understanding of the noncholinergic toxicity of organophosphorous acid triesters and methylcarbamates.

Animals↗

An introduction to the possible role of central nervous system structures in neuroendocrine-immune systems interaction.

The involvement of different regions of the brain in the immune response was investigated with the aid of small electrolytic lesions. The lesions were placed in such a way that they covered different areas of the brain stem, basal ganglia, but also some parts of the frontal cortex. The cellular immune response as well as DNA synthesis with the aid of labelled precursors was measured. The results suggest the possibility of the existence of three circuits. One circuit represents catecholaminergic cell group A1-7 in reticular formation, nucleus parabrachialis and central ncl. amygdalae. The second circuit represents serotonergic rapheal groups B6.8, hypothalamus and ncl. basomedialis of amygdala. The third circuit represents ncl. amygdalae and the medial part of frontal cortex, namely the cingulate cortex area 1-2. The close correlation between the changes of the immune response and the CNS activity was also investigated in the experiments with immunosuppressed and immunostimulated animals by measuring of the turnover of some neurotransmitters but also by recording electrocephalographic activity.

Animals↗

The role of cavitational activity in fragmentation processes by lithotripters.

The role of cavitation during shock wave exposure was poorly understood until now. Cavitational activity produces severe damage to nearby surfaces due to multiple high-speed liquid jets resulting from bubble collapse. These jet impacts can be made visible by microscopy. For investigating the presence of cavitational processes by shock waves outside and even inside of targets, we have performed the following experiments. Natural gallstones and artificial targets were examined microscopically with regard to the effects of shock pulses. Scanning electron and light microscopical investigations revealed regularly typical and uniform microjet impacts within the fissures and split lines. Since these experiments are the continuation of high-speed films of 10,000 frames/s of shock wave actions on targets, it is most likely that the shock wave produces at first split lines through the stone. Then liquid occupies these cracks. But the following shock waves create within these liquid-filled fissures cavitation and, therefore, cause the disintegration of the targets. It now becomes understandable why biliary lithotripsy is less effective than renal lithotripsy: bile fluid is a high-viscous liquid and, therefore, hinders the disintegration of stones more than low-viscous urine. Intervals between the application of shock waves in biliary lithotripsy, therefore, should improve the treatment results.

Bile↗

Experiences with lithotripters: measurements of standardized fragmentation.

A comparison of lithotripters in terms of the fragmentation efficacy was established by using artificial stones. Two hundred pulses were applied to identical calcium sulphate cubes at varied energy levels of different lithotripters. In the cubics the shock waves formed regular craters, which could be analyzed with regard to depth, diameter, and volume. Dimensions of the craters increased with increasing energy. Each shock wave source designed a typical crater form. Different efficacies of fragmentation within different lithotripters could be recognized. High focal peak pressures did not guarantee better fragmentation effects. By using different acoustic lenses in the same electromagnetic lithotripter, the influence of different focus zones of the shock wave on the fragmentation could be investigated without any changes of the energy input. Results clearly emphasize the possibility of an increase of fragmentation efficacy by changing only the focal zones and the distribution of energy within the focal area.

Cholelithiasis↗