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Biomedical subjects

U Winkler

Publications and source records attributed to U Winkler.

At least 37 records · Page 2Linked to original sources
PubMed1994

Chymase-directed serine protease inhibitor that reacts with a single 30-kDa granzyme and blocks NK-mediated cytotoxicity.

Cytotoxic NK and T lymphocytes kill virally infected cells within minutes without causing damage to themselves or bystander cells. One mechanism of killing involves exocytosis of granules containing serine proteases and perforin. Serine protease inhibitors block killing of target cells mediated by the cytotoxic lymphocytes. There are at least five different serine protease activities in cytolytic granules. Ten different serine protease sequences have been identified with the use of cDNA-specific clones. It is not known whether only one or several of these serine proteases are essential for cytolytic activity. In this study we show that an irreversible serine protease inhibitor, biotinyl-Aca-Aca-Phe-Leu-PheP(OPh)2, selectively inhibits a chymotrypsin-like (chymase) serine protease activity of rat RNK-16 granule extracts. Under the same conditions, only one 30-kDa (reduced) band was detected on protein blots. Furthermore, only one of three chymase peaks separated by hydrophobic interaction chromatography was inhibited. When this granzyme was inhibited, granule-mediated lysis of erythrocytes was diminished. NK cell killing was completely blocked when biotinyl-Aca-Aca-Phe-Leu-PheP(OPh)2 was added to cytotoxicity assays at 200 microM with rat splenocytes as effectors. By confocal fluorescence microscopy, we show that this inhibitor localizes to distinct regions within RNK-16 cells and rat NK cells. Inhibitor treatment of intact cells inactivated the chymase activity and reduced lysis found in their dense organelles. Together these data indicate that biotinyl-Aca-Aca-Phe-Leu-PheP(OPh)2 inhibits a granule chymase that is essential to cytolytic activity of NK cells.

Amino Acid Sequence↗
PubMed1994

Successful treatment of disseminated human Hodgkin's disease in SCID mice with deglycosylated ricin A-chain immunotoxins.

To evaluate the effects of deglycosylated ricin A-chain (dgA) immunotoxins against disseminated Hodgkin's lymphoma, we used RFT5.dgA (CD25) and IRac.dgA (70 kD) to treat L540Cy Hodgkin cells in severely immunodeficient SCID mice. In this model, more than 90% of the animals developed multiple lymphomas in various organs such as the lymph nodes, liver, bone marrow, and extranodal sites that killed untreated animals after a mean survival time (MST) of 36.3 days. A single intraperitoneal injection of 8 micrograms of either immunotoxin rendered 95% (RFT5.dgA) and 93% (IRac.dgA), respectively, of mice tumor-free when applied 1 day after tumor challenge. The MST of the RFT5.dgA-treated group was extended by more than 80 days (P < .00001). SCID mice treated 12 days after tumor challenge had lower remission rates (46%), suggesting that the antitumor effect of the immunotoxins depends on the number of tumor cells present. We conclude that ricin A-chain immunotoxins have potent antitumor effects against disseminated Hodgkin's tumors in SCID mice and that this model is ideally suited for the evaluation of different immunotoxin treatment modalities.

Animals↗
PubMed1994

Immunotoxins: is there a clinical value?

Drug targeting is an attractive new approach to killing malignant cells, thereby leaving normal tissue unharmed. A decisive breakthrough was the advent of hybridoma technology, making monoclonal antibodies (MoAb) available in limitless supply. To construct reagents with selectivity for certain tumor cells, MoAbs or Fab' fragments were chemically linked to ribosome-damaging toxins derived from plants or bacteria like ricin, abrin, saporin, Pseudomonas exotoxin (PE), and diphtheria toxin (DT) to form immunotoxins, which combined the selectivity of the carrier moiety with the potency of the toxin moiety. The first generation of these immunotoxins showed impressive results in vitro but in most cases disappointing antitumour effects in animals or humans. By contrast, the second generation of immunotoxins, consisting of either A chain immunotoxins with a greatly improved stability in vivo or so-called 'blocked' ricin immunotoxins, have been demonstrated to be extremely effective in several animal models. Preliminary results of the current clinical trials suggest a possible clinical use of immunotoxins in leukemia and lymphoma patients. Genetically engineered fusion toxins have become available, which consist of a growth factor or a cytokine fused to a toxin moiety. In this paper, we will review the features of the three groups of immunotoxins which are most frequently used, i.e., ricin A chain and similar immunotoxins, blocked ricin immunotoxins, and recombinant toxins constructed with Pseudomonas exotoxin or diphtheria toxin.

Clinical Trials as Topic↗
PubMed1994

The structure-function relationship of the lipases from Pseudomonas aeruginosa and Bacillus subtilis.

Within the BRIDGE T-project on lipases we investigate the structure-function relationships of the lipases from Bacillus subtilis and Pseudomonas aeruginosa. Construction of an overproducing Bacillus strain allowed the purification of > 100 mg lipase from 30 l culture supernatant. After testing a large variety of crystallization conditions, the Bacillus lipase gave crystals of reasonable quality in PEG-4000 (38-45%), Na2SO4 and octyl-beta-glucoside at 22 degrees C, pH 9.0. A 2.5 A dataset has been obtained which is complete from 15 to 2.5 A resolution. P.aeruginosa wild-type strain PAC1R was fermented using conditions of maximum lipase production. More than 90% of the lipase was cell bound and could be solubilized by treatment of the cells with Triton X-100. This permitted the purification of approximately 50 mg lipase. So far, no crystals of sufficient quality were obtained. Comparison of the model we built for the Pseudomonas lipase, on the basis of sequences and structures of various hydrolases which were found to possess a common folding pattern (alpha/beta hydrolase fold), with the X-ray structure of the P.glumae lipase revealed that it is possible to correctly build the structure of the core of a protein even in the absence of obvious sequence homology with a protein of known 3-D structure.

Amino Acid Sequence↗
PubMed1994

Experimental treatment of human Hodgkin's disease with ricin A-chain immunotoxins.

In the present paper we describe the evaluation of ricin A-chain immunotoxins for clinical application in Hodgkin's disease. The immunotoxins were constructed by chemically linking deglycosylated ricin-A to monoclonal antibodies (MoAb) recognising lymphocyte activation markers CD25, CD30, or IRac, which are expressed by Hodgkin's and Reed-Sternberg (H-RS) cells. The cytotoxic effects of the immunotoxins were investigated in vitro against L540Cy Hodgkin cells and in vivo against Hodgkin's tumors in nude mice and disseminated Hodgkin's tumors in SCID mice. MoAbs were evaluated for crossreactivity with normal human tissues and staining of sections from Hodgkin's disease tissue. Of 32 MoAbs, eight showed little crossreactivity with vital human organs and produced highly active immunotoxins. The most effective immunotoxin, RFT5 gamma l.dgA (CD25), inhibits the growth of H-RS cells at concentrations of 7 x 10(-12) M. RFT5 gamma l.dgA destroys about 60% of solid Hodgkin's tumors of 0.5 cm diameter in nude mice and induces complete remissions in 95% of SCID mice with disseminated Hodgkin's tumors when administered one day after tumor challenge. This immunotoxin binds to all H-RS cells in more than 90% of patients with Hodgkin's disease. Patients with refractory Hodgkin's disease are currently being treated in a phase-I/II clinical trial.

Animals↗
PubMed1993

Human granzyme B degrades aggrecan proteoglycan in matrix synthesized by chondrocytes.

Cartilage degradation, a hallmark of rheumatoid arthritis, is attributed to serine and metalloproteases secreted by neutrophils, synovial lining cells, macrophages, and chondrocytes. A large proportion of synovial fluid lymphocytes contains the granule-associated serine proteases granzymes A and B. We report that lysates of IL-2-stimulated lymphocytes contain an enzymatic activity (ECMase; cartilage extracellular matrix 35S release assay; extracellular matrix degrading activity) that solubilizes matrix synthesized by chondrocyte monolayers. ECMase activity is inactivated by the serine protease inhibitor diisopropylfluorophosphate, is stored in dense granules and cleaves aggrecan proteoglycans but not free glycosaminoglycans, hyaluronic acid, or type II collagen. ECMase is mediated by a cationic protein with biochemical properties identical to granzyme B, inasmuch as it preferentially hydrolyzes the substrate Boc-Ala-Ala-Asp-SBzl, immunochemically cross-reacts with an antibody that binds to a conserved amino-terminal region of lymphoid-myeloid serine proteases, and has amino-terminal sequence identity with human Q31 granzyme B. Using an agarose gel electrophoresis technique to assess cleavage of the rat sarcoma aggrecan, the catalytic efficiency of granzyme B for the digestion of aggrecan (catalytic efficiency = 1.7 x 10(7) M-1 s-1) was 425-fold faster than the catalytic efficiency reported for human stromelysin-1 at pH 7.5 (catalytic efficiency 4000 M-1 s-1) and 3200-fold faster than granzyme A. Based on these observations, we propose that granzyme B, secreted from cytotoxic lymphocytes within the rheumatoid joint, may contribute to cartilage loss by degrading resident aggrecan.

Aggrecans↗
PubMed1993

Activation of recombinant murine cytotoxic cell proteinase-1 requires deletion of an amino-terminal dipeptide.

Murine cytotoxic cell proteinase-1 (granzyme B) is a member of a family of novel serine proteinases that have been implicated to participate in destruction of target cells by cytotoxic T lymphocytes. Comparison of the sequence of the cDNA with the sequence of the protein isolated from cytoplasmic granules of cytotoxic T lymphocytes suggested that this protein may be synthesized as a preproenzyme containing an amino-terminal activation dipeptide. Here we show that this activation dipeptide regulates the activity of the enzyme in hydrolysis of its preferred substrate tert-butyloxycarbonyl-Ala-Ala-Asp-thiobenzyl ester. Lysates of COS cells transfected with a vector expressing the unmodified cytotoxic cell proteinase-1 cDNA were unable to hydrolyze this substrate, whereas lysates of cells transfected with a construct in which the activation dipeptide codons has been deleted were able to hydrolyze the substrate. In each case Western blotting of the lysates revealed a form of the proteinase with an apparent molecular weight of 27,000. We conclude that the activation dipeptide regulates activity of the enzyme. This is the first report of production of an enzymatically active recombinant cytotoxic T cell serine proteinase. The strategy for successful expression of an activated form of cytotoxic cell proteinase-1 may be applicable to other members of this proteinase family.

Amino Acid Sequence↗
PubMed1993

Rapid purification of cationic granule proteases: application to human granzymes.

This report describes a simple scheme for the simultaneous purification of cationic human granzymes A, B, and 3 from human interleukin 2 (IL-2)-activated lymphocytes. The process, which requires approximately 8 h, includes: (1) cell cavitation, (2) two centrifugation steps, (3) four granule solubilization steps, and (4) cation-exchange chromatography. Granule solubilization consists of three extractions with a hypotonic buffer (25 mM NaCl) that contained Triton X-100 followed by a final extraction in hypertonic detergent-free buffer (390 mM NaCl). We recovered approximately 35% of the trypsin-like (tryptase) activities mediated by granzymes A and 3, respectively, and approximately 25% of the asp-ase activity of granzyme B. The granzymes were identified after elution from the Mono S column by Western blot with a polyclonal antibody that reacts with a conserved amino acid sequence (9-16) of lymphoid/myeloid serine proteases. By amino-terminal sequencing, eluted granzyme A and B were indeed homogeneous. Granzyme 3, although highly enriched, appears to be contaminated with an uncharacterized granzyme. Although we have developed this scheme to rapidly isolate the granzymes, the procedure should assist the purification of secretory granule-associated cationic proteins that reside in neutrophils and mast cells as well as other cells that possess secretory function.

Amino Acid Sequence↗
PubMed1993

Pharmacokinetics and protein binding of 3-ketodesogestrel and gestodene in the serum of women during 6 cycles of treatment with two low dose oral contraceptives.

The serum concentrations of 3-ketodesogestrel (KDG) and gestodene have been measured in 30 and 31 women respectively who took low dose oral contraceptives containing 30 micrograms ethinylestradiol together with either 150 micrograms desogestrel or 75 micrograms gestodene for 6 months. On days 1, 10 and 21 of the first third and sixth treatment cycles blood samples were drawn at 0, 0.5, 1, 1.5, 2, 3, 4 and 24 h. KDG and gestodene levels were measured by radioimmunoassays and were evaluated for Cmax (peak serum concentration), tmax (time to Cmax), and AUC (area under the curve) to 4 and 24 h. The overall total gestodene concentrations were higher and the accumulation of the steroid throughout a cycle greater than that of KDG. For example, the AUC0-4 of gestodene increased in cycle 1 by a factor of 2.8 (day 10 vs. day 1) and 3.6 (day 21 vs. day 1) compared to 2.3 and 2.6 for KDG. The higher concentration of gestodene reflects a lower volume of distribution than KDG, and is consistent with gestodene binding to sex hormone binding globulin (SHBG) with a higher affinity than KDG. Concentrations of KDG and gestodene were higher on day 1 of cycles 3 and 6 than on day 1 of cycle 1. The serum concentrations of KDG and gestodene during multiple dosing cannot be predicted on the basis of single dose pharmacokinetics.

Adolescent↗
PubMed1992

[New perspectives in oncology: is selective destruction of tumor cells with immunotoxins in Hodgkin's disease an additional therapeutic alternative?].

In the present paper, the authors describe the production and testing of immunotoxins for clinical application in Hodgkin's disease. The immunotoxins were constructed by chemical coupling of deglycolysated ricin-A to monoclonal antibodies against antigens on Hodgkin's and Reed-Sternberg cells (CD25, CD30, IRac). The cytotoxic effect of the immunotoxins was investigated in vitro against Hodgkin's and Reed-Sternberg cells (H-RS) and in vivo against solid Hodgkin's tumors in nude mice and disseminated Hodgkin's tumors in SCID mice. Cross-reactivity with normal tissue and the staining behaviour observed in sections of Hodgkin's tissue of various subtypes proved important parameters for the assessment of clinical applicability. Of more than 30 evaluated MoAb's, eight immunotoxins were produced, of which six showed both, cytotoxic effects of considerable potency against Hodgkin's tumor cells and low cross-reactivity with vital human organs. The most effective immunotoxin, RFT5 gamma 1.dgA, (CD25) inhibits the growth of H-RS cells at concentrations of 7 pMol and destroys about 60% of solid Hodgkin's tumors of 0.5 cm in diameter in nude mice. This immunotoxin binds to virtually all tumor cells in more than 90% of patients with Hodgkin's disease. Sufficient quantities of RFT5 gamma 1.dgA were produced for the treatment of patients with refractory Hodgkin's disease. These patients are currently being treated in a phase I clinical trial.

Animals↗
PubMed1992

Sulfonyl fluoride serine protease inhibitors inactivate RNK-16 lymphocyte granule proteases and reduce lysis by granule extracts and perforin.

Cytolytic granules purified from natural killer lymphocytes (NK) contain a pore-forming protein (perforin) and a number of serine proteases. When these proteases are inhibited by serine protease-specific isocoumarin reagents the serine proteases are inactivated and the cytolytic activity of the granules is decreased. Paradoxically, it has been found that the general serine protease inhibitor phenylmethylsulfonyl fluoride (PMSF) frequently cannot block killing even though it inhibits many of the serine proteases. At the same time it has been reported that "purified" perforin alone can lyze cells. To address these inconsistencies we first compared the ability of PMSF and four new sulfonyl fluoride serine protease inhibitors to inhibit proteases and cell lysis. We determined the effects on lysis and the second order inhibition rate constants for five granule protease activities: ly-tryptase, ly-chymase, Met-ase (methionine cleaving), Ser-ase (serine cleaving) and Asp-ase (aspartic acid cleaving). One compound, 2-(Z-NH(CH2)2CONH)C6SO2F, was a potent inhibitor of Met-ase activity (k(obsd)/[I] = 162 M-1 s-1), ly-chymase activity (k(obsd)/[I] = 147 M-1 s-1), and granule-mediated as well as perforin-mediated lysis. PMSF was a poor inhibitor of granule proteases (k(obsd)/[I]'s less than 7 M-1 s-1 for four activities and no inhibition of Ser-ase); the lack of reactivity is consistent with the failure of PMSF to block granule lytic activity. We also prepared enriched perforin by anion exchange chromatography and showed that a ly-chymase and a Met-ase associated with perforin. By inhibiting these proteases we also inhibited lytic activity.

Animals↗
PubMed1992

[Neutral and zwitterionic detergents: dependence of biological effectiveness on critical micellar concentration].

The biological activity of various zwitterionic and nonionic detergents was studied as a function of the corresponding critical micellar concentration (CMC-values). The criteria chosen to measure biological activities were inhibition of bioluminescence, lysis and cell-killing of Vibrio fischeri, hemolysis, and inhibition of Daphnia magna. When Zwittergent-detergents were studied in three different bioassays their biological activity increased with decreasing CMC-values. However, the biological activity of various TWEEN-detergents and alkylglucopyranosides depended on CMC-values in a very different way. We therefore conclude that CMC-values, length of alkylgroups and charge are parameters not yet sufficient to predict the potential toxicity of detergents.

Animals↗
PubMed1992

The reactivity of peripheral vessels of normo- and hypertensives.

The effect of calcium antagonist nifedipine (N) was studied in the changes of blood pressure, total peripheral resistance, activity of the transport membrane ATPase of erythrocyte ghosts, the plasma level of digitalis-like factor and the plasma renin activity. The studies were performed in 10 healthy volunteers and in 19 hypertensive patients after the intake of a single dose of 20 mg N. The changes were studied in the hypertensives after the intake of the drug in daily doses of 3 times 10 mg over 4 weeks, too. The systolic and diastolic blood pressure and peripheral resistance of the forearm decreased in hypertensives after a single dose of nifedipine as well as after the treatment with 30 mg daily over 4 weeks (170.8/109.5 vs 145.3/98.3 mmHg). As compared with the membrane ATPase activity of normotensives, that of the hypertensives was distinctly depressed (0.403 vs 0.321 mumol P(i).mg-1.h-1; p less than 0.01), while after N treatment, the enzyme activity increased to values of those of the normotensives 0.403 mumol P(i).mg-1.h-1). The mean peripheral resistance was not significantly depressed after the long-term treatment with N (2,085 vs 1,535 dyn.s-1.cm-5), while in several hypertensives (9 of 19) a distinct reduction was measured. Analogous results were found in case of the mean renin activity and the activity of several hypertensives after the N treatment. The N effect on the membrane ATPase system is discussed in connection with the hypothesis of Blaustein [1977] (Na(+)- with consecutive Ca(2+)-overload of the cell) and a possible influence of the drug on the electrolyte transport via membrane.

Adenosine Triphosphatases↗
PubMed1992

Treatment of endometriosis with leuprorelin acetate depot: a German multicentre study.

During the past decade, the development of various gonadotrophin-releasing hormone (Gn-RH) agonists, which induce reversible hypo-oestrogenism has opened a new area in the medical management of endometriosis. In an open, multicentre phase III study, the efficacy, tolerance and safety of the Gn-RH agonist leuprorelin acetate were tested. The preliminary results of 104 women treated in seven German centres are presented. Pelvic endometriosis was diagnosed by laparoscopy and classified according to the American Fertility Society scoring system: 33% of patients had minimal, 22% mild, 28% moderate and 8% severe endometriosis and in 9% no pathological results were obtained. The patients' mean age was 30 +/- 6 years and 66 had infertility problems. Treatment was started within the first 3 days of the menstrual cycle and consisted of a subcutaneous injection of leuprorelin acetate 3.75 mg, repeated once monthly over 24 weeks. A follow-up period of 12 months after the last injection has been completed in 70 patients, including a second laparoscopy. At all visits, symptoms were evaluated, physical examinations performed, and blood samples collected for haematological screening, serum chemistry determinations and measurement of the gonadotrophins oestradiol and progesterone and leuprorelin acetate. The median score at laparoscopy fell from 12 before operation to 8 after operation and 2 after treatment with leuprorelin acetate. Of the total number of patients, 89% had improvements in their endometriosis, 8% a deterioration and 3% no change. Patients reported improvement in the following: dysmenorrhoea 93%, dyspareunia 62% and pelvic pain 70%. However, all women complained of at least one of the following symptoms: hot flushes 86%, sleep disturbance 62%, sweating 61%, headache 41%, nausea 32% and depression 20%. Fifty-five percent of patients reported additional side effects such as vaginal dryness, fatigue and lower abdominal pain. After the third injection, amenorrhoea persisted in 94% of the women. Four weeks after the first leuprorelin acetate injection median concentrations of oestradiol fell from 45 pg/ml to 11 pg/ml, follicle-stimulating hormone from 7 U/L to 3 U/L and luteinising hormone from 5 U/L to 1 U/L and remained almost unchanged over the observation period. During the 6 months' treatment, laboratory parameters showed no significant deviations from normal; only total cholesterol, high-density lipoprotein cholesterol and alkaline phosphatase increased. Treatment results were judged as good and satisfactory in 82% and 11% of cases, respectively. On the basis of this study, it can be concluded that leuprorelin acetate treatment is safe, well tolerated and effective in the medical management of endometriosis and endometriosis-related complaints.

Adult↗
PubMed1992

Influence on hormone levels, lipid metabolism and reversibility of endocrinological changes after leuprorelin acetate depot therapy.

The effect of leuprorelin acetate depot on the endocrine system and on lipid metabolism was evaluated in a multicentre, noncomparative study. During the first month of treatment, suppression of serum oestradiol levels to below 20 pg/ml was achieved and luteinising hormone and follicle-stimulating hormone levels were reduced to less than 50% of pretreatment values. A negative influence on lipid metabolism was not recorded. The high-density lipoprotein/low-density lipoprotein ratio did not change during therapy. Resumption of menstruation occurred within a mean period of 3 months after the last leuprorelin acetate depot injection.

Bone Density↗
PubMed1992

Plasmatic haemostasis in gonadotrophin-releasing hormone analogue therapy: effects of leuprorelin acetate depot on coagulatory and fibrinolytic activities.

The plasmatic parameters of coagulatory and fibrinolytic activity were studied in 15 patients with biopsy-proven endometriosis treated with leuprorelin acetate for 6 months. Bleeding time remained constant, indicating the absence of increased bleeding tendencies. The activity of the main inhibitor of the fibrinolytic response, plasminogen activator inhibitor, was reduced by 25%, suggesting an improvement in fibrinolytic reactivity. Plasma levels of fibrin degradation fragments were reduced by 35%, suggesting a marked reduction in the rate of fibrin generation and degradation. A simultaneous reduction in thrombin-antithrombin III complexes and prothrombin fragment 1 + 2 (-10%) indicated that this effect was induced by reduced procoagulant activity, ie, thrombin generation. These data indicate that in gonadotrophin-releasing hormone (Gn-RH) analogue therapy the basal rate of coagulatory processes is reduced. The frequency and extent of fibrin-generating and degrading processes are reduced, suggesting a beneficial effect of Gn-RH analogues on the risk of thromboembolic disease.

Antithrombin III↗
PubMed1992

Experience with leuprorelin acetate depot in the treatment of fibroids: a German multicentre study.

Between October 1988 and October 1990 in a noncomparative multicentre study, 114 patients were treated for uterine fibroids with the gonadotrophin-releasing hormone (Gn-RH) agonist, leuprorelin acetate depot. The mean age of the women was 33 years and 55.3% of them had a history of infertility. After confirmation of the diagnosis by ultrasound and/or operation, treatment began between day 1 and 3 of the cycle with leuprorelin acetate depot 3.75 mg subcutaneously. Therapy was carried out for a total of 6 months with one injection every 4 weeks. Treatment was paralleled by measurements of endocrine and metabolic parameters, estimation of myoma and uterine size by ultrasound and self-reporting of the patients of drug-related complaints. Four of the 114 women did not complete the whole treatment, two of them because of general side effects, one because of carcinophobia and unsatisfactory regression of the myoma and the last one for unspecified reasons. During treatment, a mean reduction of the uterine volume of about 67% was observed, in conjunction with shrinkage of the myoma in 92.1% of cases (mean decrease of 56% of the fibroids) with a large interindividual difference. Maximal diminution of uterine and fibroid size had been nearly completely reached within the first 12 weeks of therapy. After 4 weeks of the Gn-RH agonist depot most of the patients had achieved postmenopausal status, which continued throughout the remaining 20 weeks of treatment. In accordance with this finding, the majority of general side effects was due to the hypo-oestrogenic endocrine status. Liver and lipid metabolism was almost unaffected, although increasing calcium and alkaline phosphatase serum levels as well as an increased urinary calcium/creatinine ratio demonstrated an increased metabolic turnover of the bone. Haemoglobin concentrations, however, increased in those cases with fibroid-related anaemia. Thus the slow-release form of leuprorelin acetate is an adjunct to myomectomy especially in those women in whom family planning is not yet completed.

Adult↗