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Biomedical subjects

Peter Fritsch

Publications and source records attributed to Peter Fritsch.

At least 19 recordsLinked to original sources

Prospective, randomized, multicenter, double-blind placebo-controlled trial comparing adjuvant interferon alfa and isotretinoin with interferon alfa alone in stage IIA and IIB melanoma: European Cooperative Adjuvant Melanoma Treatment Study Group.

PURPOSE: The combination of interferon alfa (IFNalpha) and isotretinoin has shown a direct antiproliferative effect on human melanoma cell lines, but it remained unclear whether this combination is more effective than IFNalpha alone in patients with metastatic melanoma. We evaluated safety and efficacy of IFNalpha and isotretinoin compared with IFNalpha alone as adjuvant treatment in patients with primary malignant melanoma stage IIA and IIB. PATIENTS AND METHODS: In a prospective, randomized, double-blind, placebo-controlled trial, 407 melanoma patients in stage IIA (301 patients) and IIB (106 patients) were randomly assigned to either IFNalpha and isotretinoin (isotretinoin group; 206 patients) or IFNalpha and placebo (placebo group; 201 patients) after excision of the primary tumor. IFNalpha was administered three times a week at a dose of 3 million units subcutaneously for 24 months. Isotretinoin at a dose of 20 mg for patients < or = 73 kg, 30 mg for patients greater than 73 kg, or placebo daily for 24 months. RESULTS: A scheduled interim analysis revealed no significant differences in survival rates, with the isotretinoin group and the placebo group showing 5-year disease-free survival rates of 55% (95% CI, 46% to 65%) and 67% (95% CI, 59% to 75%), respectively, and overall 5-year survival rates of 76% (95% CI, 67% to 84%) and 81% (95% CI, 74% to 88%), respectively. The trial was stopped for futility. CONCLUSION: The addition of isotretinoin to an adjuvant treatment of low-dose IFNalpha in patients with stage IIA and IIB melanoma had no significant effect on disease-free or overall survival and is therefore not recommended.

Adolescent↗

Higher concentrations of heparin and hirudin are required to inhibit thrombin generation in tissue factor-activated cord plasma than in adult plasma.

Neonatal plasma clots slower than adult plasma, and only 30-50% of peak adult thrombin activity can be produced in neonatal plasma when high amounts of tissue factor (TF) are added to trigger clotting, as used in standard clotting assays. Plasma activation by addition of low amounts of TF probably better reflects conditions in vivo. Under these conditions, cord plasma clots faster than adult plasma. In the present study, we show that after activation with low amounts of TF, higher amounts of the anticoagulants heparin and hirudin are required in cord plasma for effective inhibition of thrombin generation compared with adult plasma. After strong activation with high amounts of TF (30 microM), the thrombin potential was significantly more suppressed in cord plasma compared with adult plasma in the presence of 0.4 IE/mL heparin (-92 versus -75%; p < 0.01) and in the presence of 2 IE/mL hirudin (-18 versus -8%; p < 0.01). In contrast, after weak activation with low amounts of TF (30 pM), the thrombin potential was significantly more suppressed in adult plasma compared with neonatal plasma in the presence of 0.025 IE/mL heparin (-93 versus -8%; p < 0.01) and in the presence of 2 IE/mL hirudin (-89 versus -48%; p < 0.01). Our results show that in neonates, effects of anticoagulants very much depend on the type of activation used to initiate clotting, and doses of anticoagulants should not be derived from studies done in adults, because potentially higher doses of anticoagulants may be required.

Adult↗

[The third year].

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Dermatology↗

Bath-water PUVA therapy with 8-methoxypsoralen in mycosis fungoides.

PUVA therapy is widely used for early stage mycosis fungoides. While the efficacy of PUVA with oral 8-methoxypsoralen (8-MOP) is well documented, the use of its topical variation, bath-water PUVA therapy with 8-MOP has not been studied. The purpose of this study was to assess the effect of 8-MOP bath-water PUVA therapy in adult patients with early stage mycosis fungoides. We retrospectively evaluated the outcomes of bath-water delivery of 8-MOP (1 mg l(-1)) in 16 patients with early stage mycosis fungoides. In all patients complete response was achieved after a mean duration of 63 days requiring 29 treatments and a mean cumulative UVA dose of 33 J cm(-2). The time to relapse after complete clinical clearance was 45.6 (+/-9.2) weeks. In comparison, oral PUVA therapy with 8-MOP resulted in complete response after 64.5 days (25.8 treatments) with a mean relapse-free period of 30 (+/-3.5) weeks. We conclude that bath-water PUVA therapy with 8-MOP is a valuable photo-therapeutic alternative, which should be considered for patients in whom systemic psoralen cannot be used.

Administration, Cutaneous↗

Additive effects of anticoagulants: recombinant human activated protein C and heparin or melagatran, in tissue factor-activated umbilical-cord plasma.

Severe sepsis in children or adults may cause a life-threatening coagulopathy, with widespread consumption of activated protein C (APC); recombinant human APC (rhAPC) is a promising candidate anticoagulant treatment. We investigated the effects of rhAPC and other anticoagulants on coagulation triggered by adding small quantities of lipidated tissue factor to human umbilical-cord plasma in vitro. rhAPC, unfractionated heparin (UH), and melagatran (a direct thrombin inhibitor) were studied individually, and in combinations of rhAPC with either UH or melagatran. rhAPC alone dose-dependently prolonged the activated partial-thromboplastin time (aPTT) but not the prothrombin time (PT), and dose-dependently suppressed two indices of thrombin generation, namely prothrombin fragment F 1.2 (F 1.2) generation and thrombin-antithrombin (TAT) complex formation. UH alone dose-dependently prolonged the aPTT but not the PT, while melagatran alone dose-dependently prolonged both the aPTT and the PT. Adding either UH or melagatran dose-dependently augmented the capacity of rhAPC to suppress F 1.2 generation (with addition of UH showing a greater effect) and TAT formation (with addition of melagatran showing a greater effect). Both the capacity of UH to prolong the aPTT and the capacity of melagatran to prolong the aPTT and the PT were augmented by adding rhAPC. In our in-vitro study, adding either UH or melagatran augmented the capacity of rhAPC to suppress thrombin generation in human umbilical-cord plasma, with the anticoagulant effect of melagatran being more predictable than that of UH. Hence, combining rhAPC with melagatran might be a valuable therapeutic option in patients with severe sepsis.

Anticoagulants↗

Expression of C-type lectin receptors by subsets of dendritic cells in human skin.

C-type lectins are cell surface receptors that recognize carbohydrate structures which are often part of microbial pathogens. Several of these molecules are expressed on dendritic cells and are involved in antigen uptake. Expression of C-type lectins on dendritic cells of the human skin, i.e. Langerhans cells of the epidermis and dermal dendritic cells, has been incompletely studied to date. We therefore investigated C-type lectins in situ and on dendritic cells obtained by migration from skin explants by immunofluorescence and flow cytometry. Emphasis was laid on expression patterns of DEC-205/CD205 and BDCA-2, a marker for plasmacytoid dendritic cells. Langerhans cells in situ expressed low levels of DEC-205. Expression was upregulated upon maturation in skin explant organ culture. Most dermal dendritic cells were found to be positive for DEC-205 and DC-SIGN/CD209. Few BDCA-2-expressing cells were found in most skin samples. They were located in small groups in the dermis close beneath the basement membrane. The vast majority of all types of dendritic cells in normal human skin was of immature phenotype, i.e. did not express DC-LAMP/CD208. It is concluded that normal appearing human skin harbors different subsets of dendritic cells including few scattered BDCA-2-expressing cells, presumably plasmacytoid dendritic cells, expressing variable sets of C-type lectin receptors. This may critically contribute to the capacity of the skin immune system to flexibly respond to the world of microbial pathogens.

Antigens, CD↗

"Wait and see" strategy in localized neuroblastoma in infants: an option not only for cases detected by mass screening.

Neuroblastomas in infants may regress or mature spontaneously. Consequently, some authors have applied a "wait and see" strategy for tumors found by urinary mass screening. Recently, improved technique and increasing frequency of ultrasound examinations have led to an increase of neuroblastoma cases in pre- and post-natal period. We describe five cases, four diagnosed by routine ultrasound examination and one detected by urinary mass screening, who were monitored with a "wait and see" strategy in order to spare surgery. Median age at diagnosis was 4 months (range 2-10 months). All tumors were adrenal neuroblastomas. All patients met the following criteria: localized tumors, tumor size less than 5 cm in diameter, absence of invasive growth, vanillylmandelic acid (VMA) and homovanillic acid (HVA) less than 50 microg/mg creatinine, and informed consent of parents. Monitoring was performed by monthly ultrasound examinations and urine catecholamine analysis. Median follow-up is 14 months (5-28 months). Three tumors showed spontaneous regression, one is still under observation. In one patient the tumor increased in size and was resected after 14 months of observation displaying favorable histology, but chromosome 1p imbalance. Previous reports describe the adoption of a "wait and see" strategy in selected cases of localized neuroblastoma detected by mass screening. Our study confirms that this strategy may be similarly applied in incidentally or clinically detected cases. However, possible benefit has to be carefully balanced against possible risks.

Disease Progression↗

In vitro treatment of dendritic cells with tacrolimus: impaired T-cell activation and IP-10 expression.

BACKGROUND: High doses (10(-6)-10(-8) M) of tacrolimus (FK506) were reported to induce a type-2 T-helper cell (Th2)-promoting function in developing dendritic cells (DC). We used a therapeutic dose (2.4 x 10(-9 )M) of tacrolimus to investigate its effect on human monocyte-derived DC. METHODS: Using untreated and treated immature and mature DC we compared T cell-activating capacity, surface marker expression, T cell and DC cytokine profile and transcription of genes coding for a panel of DC function-related molecules. RESULTS: Tacrolimus-treated mature DC had reduced T-cell stimulatory capacity. Although interleukin (IL)-12 production of DC was impaired, they did not promote Th2 development as T cells activated by tacrolimus-treated DC produced less interferon (IFN)-gamma, IL-4 and IL-10. The up-regulation of the T-cell activation marker CD69 and the production of IL-2 were impaired. In addition, tacrolimus-treated DC produced less IP-10 (CXCL10), which is known to be involved in allograft rejection. Other molecules related to DC function remained unchanged. CONCLUSIONS: Tacrolimus treatment reduces the ability of DC to stimulate T cells and the impaired production of DC-derived IP-10 (CXCL10) and IL-12 might play a role in the immunosuppressive action of tacrolimus.

Cell Culture Techniques↗

The anticoagulant action of recombinant human activated protein C (rhAPC, Drotrecogin alpha activated): comparison between cord and adult plasma.

The present study was performed to compare the anti-coagulant efficiency of recombinant human activated protein C (rhAPC) in cord with that in adult plasma. RhAPC is a promising candidate to improve the outcome of severe sepsis. However, different anticoagulant efficiency of rhAPC in cord compared with adult plasma has to be expected due to physiological low plasma levels of tissue factor pathway inhibitor (TFPI) and antithrombin (AT) present in neonates, two inhibitors known to markedly influence the anticoagulant action of APC. Clot formation was induced in our experiments by addition of high (30 micro M) or low (20 pM) amounts of lipidated tissue factor (TF). High amounts of TF are conventionally applied in standard clotting assays, whereas plasma activation with low amounts of TF probably better matches the conditions in vivo. We demonstrate that under low coagulant challenge increasing amounts of rhAPC (0.1-0.5 micro g/ml final plasma concentration) dose-dependently prolonged clotting time and suppressed thrombin potential and prothrombin fragment 1+2 generation in both cord and adult plasma. The same was true for experiments performed under high coagulant challenge when 4-16 micro g/ml of rhAPC were added. Whereby, cord plasma was significantly more susceptible to addition of rhAPC in the presence of high amounts of TF and adult plasma was significantly more susceptible to addition of rhAPC in the presence of low amounts of TF. We demonstrate that increased anticoagulant efficiency of rhAPC in adult plasma under low coagulant challenge is attributable to the physiological high levels of TFPI and AT present in adults.

Adult↗

Effects of pretreatment with clopidogrel on platelet and coagulation activation in patients undergoing elective coronary stenting.

BACKGROUND: Current data suggest that pretreatment with clopidogrel (in addition to aspirin) prior to elective percutaneous coronary intervention (PCI) might be associated with a reduced incidence of subsequent adverse ischemic events. The aim of this placebo-controlled study was to find out whether an extended pretreatment period with clopidogrel before an elective PCI might confer a superior inhibition of the platelet activation and aggregation than clopidogrel given not until PCI. METHODS: Twenty patients with stable angina being already on aspirin were randomly assigned to receive the loading dose of 300 mg clopidogrel, either 24 h before or immediately after stent implantation. At several time points before and after PCI, the activation of both the platelet and the coagulation system was determined by measuring beta-thromboglobulin (beta-TG) and prothrombin fragment f1.2 (f1.2), respectively, in venous blood and in blood emerging from a microvascular injury (shed blood). RESULTS: Pretreatment with clopidogrel before PCI exhibited a slight reduction of beta-TG (from 178 to 139 ng/ml, p=0.085) and of f1.2 (from 0.81 to 0.75 nmol/l, p=0.045) in venous blood. Heparin administration (at the beginning of PCI) resulted in a 65% inhibition of ss-TG (from 10,590 to 2833 ng/ml) and 90% inhibition of f1.2 formation (from 38.7 to 4.2 nmol/l) in shed blood of patients with clopidogrel pretreatment. The extent of inhibition was, however, comparable to that observed in patients without clopidogrel pretreatment (beta-TG: from 8025 to 2812 ng/ml, 76% inhibition, p=0.47; f1.2: from 34.9 to 3.8 nmol/l, 86% inhibition, p=0.80). After PTT normalisation (6 h after PCI), levels of beta-TG and f1.2 both in venous blood and in shed blood did not differ between the two treatment regimens up to 48 h after PCI. CONCLUSION: Pretreatment with clopidogrel did not result in a pronounced inhibition of the platelet and coagulation system activation in patients on aspirin undergoing elective coronary stent implantation.

Angina Pectoris↗

[Cholesterol embolism after renal transplantation].

A 70-year-old woman developed localized livedo racemosa on the right buttock 2 months after renal transplantation. The suspected diagnosis of cholesterol embolism was confirmed by histopathological demonstration of cholesterol crystals in the wall of a small artery. The gluteal region is supplied by blood vessels that branch off the internal iliac artery distal to the usual anastomosing site of the donor kidney. Cholesterol emboli dislocated in the course of a kidney transplantation can reach the gluteal region. Cholesterol embolism after renal transplantation as well as the observation of cholesterol crystals in the histological preparation are rare findings.

Aged↗

A novel role for IL-3: human monocytes cultured in the presence of IL-3 and IL-4 differentiate into dendritic cells that produce less IL-12 and shift Th cell responses toward a Th2 cytokine pattern.

Dendritic cells (DC) derived from plasmacytoid precursors depend on IL-3 for survival and proliferation in culture, and they induce preferentially Th2 responses. Monocytes express not only GM-CSF receptors, but also IL-3Rs. Therefore, we examined whether IL-3 had an effect on the functional plasticity of human monocyte-derived DC generated in a cell culture system that is widely used in immunotherapy. DC were generated with IL-3 (instead of GM-CSF) and IL-4. Yields, maturation, phenotype (surface markers and Toll-like receptors), morphology, and immunostimulatory capacity were similar. Only CD1a was differentially expressed, being absent on IL-3-treated DC. In response to CD40 ligation DC generated in the presence of IL-3 secreted significantly less IL-12 p70 and more IL-10 compared with DC grown with GM-CSF. Coculture of naive allogeneic CD4(+) T cells with DC generated in the presence of IL-3 induced T cells to produce significantly more IL-5 and IL-4 and less IFN-gamma compared with stimulation with DC generated with GM-CSF. These data extend the evidence that different cytokine environments during differentiation of monocyte-derived DC can modify their Th cell-inducing properties. A hitherto unrecognized effect of IL-3 on DC was defined, namely suppression of IL-12 secretion and a resulting shift from Th1 toward Th2.

Adjuvants, Immunologic↗

Matrix metalloproteinases 9 and 2 are necessary for the migration of Langerhans cells and dermal dendritic cells from human and murine skin.

Dendritic cells migrate from the skin to the draining lymph nodes. They transport immunogenic MHC-peptide complexes, present them to Ag-specific T cells in the T areas, and thus generate immunity. Migrating dendritic cells encounter physical obstacles, such as basement membranes and collagen meshwork. Prior work has revealed that matrix metalloproteinase-9 (MMP-9) contributes to mouse Langerhans cell migration. In this study, we use mouse and human skin explant culture models to further study the role of MMPs in the migration and maturation of skin dendritic cells. We found that MMP-2 and MMP-9 are expressed on the surface of dendritic cells from the skin, but not from other sources. They are also expressed in migrating Langerhans cells in situ. The migration of both Langerhans cells and dermal dendritic cells is inhibited by a broad spectrum inhibitor of MMPs (BB-3103), by Abs to MMP-9 and -2, and by the natural tissue inhibitors of metalloproteinases (TIMP), TIMP-1 and TIMP-2. Inhibition by anti-MMP-2 and TIMP-2 define a functional role for MMP-2 in addition to the previously described function of MMP-9. The importance of MMP-9 was emphasized using MMP-9-deficient mice in which Langerhans cell migration from skin explants was strikingly reduced. However, MMP-9 was only required for Langerhans cell migration and not maturation, since nonmigrating Langerhans cells isolated from the epidermis matured normally with regard to morphology, phenotype, and T cell stimulatory function. These data underscore the importance of MMPs, and they may be of relevance for therapeutically regulating dendritic cell migration in clinical vaccination approaches.

Animals↗