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Biomedical subjects

G Kraus

Publications and source records attributed to G Kraus.

At least 19 recordsLinked to original sources
PubMed2001

Combined radiochemotherapy of locally advanced unresectable pancreatic adenocarcinoma with mitomycin C plus 24-hour continuous infusional gemcitabine.

BACKGROUND: In locally advanced pancreatic cancer, the combination of chemotherapy with radiotherapy is gaining increasing importance; although, in view of the reported long-term results of several contemporary trials, further improvements are certainly warranted. The aim of the present study was to evaluate the effectiveness and safety of a combined-treatment modality consisting of systemic chemotherapy with 24-h continuous infusional gemcitabine and mitomycin C, plus external beam radiotherapy in patients with localized unresectable adenocarcinoma of the pancreas. METHODS AND MATERIALS: Systemic chemotherapy consisted of mitomycin C 8 mg/m2 given as i.v. bolus injection on day 1 and gemcitabine administered as a 24-h continous infusion once weekly for 3 of 4 weeks. The starting dose of gemcitabine was 100 mg/m2 and dose levels were escalated in consecutive cohorts of 3-6 patients to 130 and 160 mg/m2, utilizing an escalating-dose Phase I trial design. Radiation therapy using megavolt irradiation (total dose, 45 Gy, 1.8 Gy/day) of 6 MV photons or greater with a 3- or 4-field technique was delivered concurrently for 5-6 weeks. RESULTS: Between January 1997 and August 1998, a total of 15 patients were enrolled in this trial, all of whom were assessable for toxicity, response, and survival. The dose-limiting toxicities at the 160 mg/m2 gemcitabine level were myelosuppression, specifically neutropenia +/- thrombocytopenia, and gastrointestinal symptoms, including stomatitis, vomiting, and diarrhea. Only 1 partial response was observed (7%), and disease was stabilized in 10 additional patients (67%). The median time to progression was 5.5 months (range, 2-12 months). Whereas all patients developed distant metastases, locoregional failure occurred in only 3. The median survival time was 8.3 months (range, 2.5 to 22.0+ months), and the 1-year survival rate was 13.3%. CONCLUSION: The MTD of gemcitabine when given as prolonged infusion in combination with mitomycin C and radiation therapy was 130 mg/m2/week. Therapeutic results suggest that combined chemoradiation with this regimen is feasible and effective for local control of pancreatic cancer, but essentially ineffective in counteracting metastatic tumor growth.

Adenocarcinoma↗
PubMed2001

The use of real-time PCR and fluorogenic probes for rapid and accurate genotyping of newborn mice.

Real-time PCR and fluorogenic probes were combined in a simple, rapid and sensitive method to genotype murine breeding stocks and their progeny for a point mutation. DNA from tail biopsies of newborn mice was mixed with amplification primers and fluorogenic hybridization probes in a PCR mixture. The primers were designed to amplify a region of the Fas-Ligand gene including the site for the gld natural point mutation. The fluorogenic hybridization probes overlaid this target sequence and were used to detect amplification of the PCR fragment as well as determine the presence of the point mutation using fluorescence resonance energy transfer (FRET). Both mutated and wild-type forms of the gene fragment were amplified as detected with real-time PCR. Melting curve profiles completed on each amplified sample revealed the genotype for each mouse. These genotypes were confirmed by sequencing the amplified fragments. These results suggest real-time spectrofluorometric PCR techniques incorporating FRET-based hybridization probes may be used for rapid, sensitive, inexpensive and reliable genotyping.

Animals↗
PubMed2001

Rapid and specific detection of the Mycobacterium tuberculosis complex using fluorogenic probes andreal-time PCR.

A rapid and sensitive strategy for the specific identification of Mycobacterium tuberculosis (TB) was designed and evaluated using crude mycobacterial lysates. The speed of real-time polymerase chain reaction (PCR) was combined with the sensitivity of fluorogenic probes to confirm the presence of mycobacteria as well as specifically identify the presence of members of the mycobacteria tuberculosis complex (MTC) in a single-tube assay. Oligonucleotides were designed to amplify the internal transcribed spacer (ITS) from several mycobacterial species. Specific fluorogenic probes were included in the PCR reaction for the identification of TB as well as Mycobacterium bovia and Mycobacterium africanum in bacterial lysates. The combination of TB-specific fluorogenic probes with real-time PCR formed an approach determined to be fast (less than 40 min), sensitive (less than 800 copies of DNA) and reliable for the specific detection of the MTC. Our data demonstrate the use of real-time PCR and fluorogenic probes in a rapid and sensitive assay to distinguish members of the MTC from other mycobacterial species.

DNA Primers↗
PubMed2001

The "A-B-C's" of the cluster B's: identifying, understanding, and treating cluster B personality disorders.

This article is a summary of some of the more recent research on the diagnosis, etiology, and treatment of Cluster B personality disorders (antisocial, histrionic, borderline, and narcissistic). Research on psychological, psychosocial, and biological perspectives of these disorders is presented. Individual psychotherapy, group psychotherapy, and other forms of multi-person therapies are also discussed. Finally, perspectives on issues of countertransference when treating these personality-disordered patients are addressed.

Countertransference↗
PubMed2001

11C-methionine PET imaging of leptomeningeal metastases from primary breast cancer--a case report.

Leptomeningeal metastases (LM) is often an elusive disease frequently diagnosed at an advanced clinical stage. Early diagnosis may allow for prompt initiation of treatment with minimal tumor burden and maximal chance of survival, especially in solid tumors such as breast cancer. Although the method of choice for imaging LM currently is by gadolinium enhanced magnetic resonance imaging (MRI), the technique has a high sensitivity but low specificity. We report the first case of Carbon 11-labelled methionine (Cmet) positron emission tomography (PET) imaging of leptomeningeal metastases in a patient with primary breast cancer. This patient presented with clinical features suggestive of LM, but had inconclusive cerebrospinal fluid (CSF) findings. Although, the contrast enhanced MRI revealed calvarial and meningeal lesions, it is known that meningeal enhancement on MRI does not always indicate metastases. In this clinical dilemma the strong methionine uptake on PET helped steer the diagnosis in favor of cancerous infiltration even before the CSF cytology became positive for malignancy.

Breast Neoplasms↗
PubMed2001

Long-term RNase P-mediated inhibition of HIV-1 replication and pathogenesis.

Advances in genetic analysis and a greater understanding of human immunodeficiency virus (HIV) molecular pathogenesis have identified critical viral targets for gene interference strategies. RNase P molecules have been proposed as a novel approach for gene targeting based upon their potent catalytic activity, as well as versatile external guide sequence (EGS) which can be modified to specifically recognize almost any target mRNA. We designed a truncated EGS to specifically recognize the highly conserved U5 region of HIV-1 mRNA and mediate subsequent cleavage of hybridized mRNA by the RNase P enzyme component. The active U5-EGS (560), as well as a disabled U5 EGS (560D) control, were cloned into plasmids containing proviral constructs and transfected into a CD4(+) T cell line that was thereafter infected with HIV-1 MN. CD4(+) T cells treated with the active U5 EGS (560) were observed to maintain CD4(+) expression and did not produce HIV p24 gag antigen, form syncytia or undergo apoptosis up to 30 days after infection. Identical cells expressing the inactivated form of the U5 RNase P EGS completely down-regulated CD4 expression, produced elevated levels of HIV-1, formed large syncytia and underwent apoptosis similar to untreated cells. HIV-1 replication and related cytopathology can be effectively inhibited in CD4(+) T cells expressing a protective U5 EGS (560).

Annexin A5↗
PubMed2000

Prevention of graft vessel disease by combined FTY720/cyclosporine. A treatment in a rat carotid artery transplantation model.

BACKGROUND: Graft vessel disease (GVD) is an important problem often responsible for late graft loss. The effects of FTY720, an immunomodulator with a novel mechanism of action were investigated in combination with cyclosporine A (CsA) in a carotid artery allograft model. METHODS: A segment of the carotid artery of Lewis rats was replaced by a DA allograft. Seven groups of eight rats were treated for 8 weeks with vehicle (P), CsA 0.3 (C0.3), 1 (C1) or 3 (C3) mg x kg(-1).day(-1) or a combination of CsA 1 with FTY 0.01 (C1F0.01), 0.03 (C1F0.03), and 0.1 (C1F0.1) mg x kg(-1).day(-1). Lumen area was estimated by magnetic resonance imaging, peripheral lymphocyte count and drug concentrations were determined at 1 and 8 weeks. Neointima, media, and lumen area were measured morphometrically. Intimal and adventitial infiltration of mononuclear cells, and medial smooth muscle cells number was assessed using a score. RESULTS: FTY720 did not influence CsA blood concentrations. FTY720 but not CsA decreased the PLC dose dependently. Magnetic resonance imaging revealed that treatment groups have larger lumen size than group P. Histological and morphometric evaluation showed that all aspects of GVD were dose dependently suppressed by treatment and lumen narrowing was prevented. CONCLUSIONS: CsA, at clinically relevant blood levels, suppressed GVD only partly. The addition of FTY720 was well tolerated and completely suppressed GVD development. In vivo lumen size did not correlate with the histologically estimated neointimal thickness.

Animals↗
PubMed2000

The novel immunosuppressant FTY720 induces peripheral lymphodepletion of both T- and B-cells in cynomolgus monkeys when given alone, with Cyclosporine Neoral or with RAD.

OBJECTIVE: FTY720 is a new immunosuppressant active in transplantation models, which modulates lymphocyte recirculation, leading to transient peripheral lymphopenia and increased lymphocytes in lymph nodes and Peyer's patches. Here, we investigated the susceptibility of cynomolgus monkeys to FTY720 given orally either alone or in combination with two other immunosuppressants, Cyclosporin Neoral or RAD, as an introductory study to transplantation protocols. METHODS: Each of the three phases of the study comprised a 3-week treatment period with FTY720 administered daily orally at 0.3, 0.1 or 0.03 mg/kg/day, respectively, followed by a 3-week recovery. FTY720 was given as single compound during the first week and in combination with Neoral at 20 mg/kg/day p.o. or RAD at 0.5 mg/kg/day p.o. during the subsequent 2 weeks. MAIN FINDINGS: These treatment regimen were well tolerated, except for some body weight loss at high FTY720 dose (0.3 mg/kg/day). FTY720 treatment resulted in a rapid decrease of white blood cell counts which reached a plateau after 3 days. A decrease in both T- and B-lymphocyte counts by up to 80-90% was seen with FTY720 doses of 0.1 and 0.3 mg/kg/day. FTY720 blood levels, both trough levels and AUC(0-24 h), showed a linear relationship with FTY720 dose. The reduction in lymphocyte counts was not directly proportional to FTY720 blood levels. The exposure to FTY720 significantly increased upon coadministration of Neoral. This pharmacokinetic interaction was not observed for coadministration of RAD. However, the peripheral lymphodepletion was slightly increased after coadministration of RAD but not of Neoral. This may be related to the intrinsic effects of RAD on hematopoietic cells. CONCLUSIONS: FTY720 given orally was effective in terms of peripheral T- and B-lymphodepletion and was well tolerated in cynomolgus monkeys even in combination with Cyclosporine Neoral or RAD, indicating that such combination protocols could be used in allo- and xenotransplantation in this species. However, the data indicate a potentiation of FTY720 exposure by CsA coadministration and additional lymphodepletion by coadministration of FTY720 and RAD which should be carefully monitored.

Administration, Oral↗
PubMed1999

A novel immunosuppressant, FTY720, induces peripheral lymphodepletion of both T- and B cells and immunosuppression in baboons.

OBJECTIVE: FTY720, a new immunosuppressant active in transplantation models, modulates lymphocyte re-circulation, leading to peripheral lymphopenia and increased lymphocytes in lymph nodes and Peyer's patches. Here, we investigated the susceptibility of baboons to FTY720 as an introductory study to transplantation protocols. METHODS: FTY720 was administered orally to Chacma baboons at 0.3 or 0.1 mg/kg/day for 3 days or at 0.03 mg/kg/day for 10 days. Haematological parameters, lymphocyte phenotype (CD3, CD4, CD8, CD20), cell apoptosis, ex vivo blood cell proliferation in response to mitogens and drug blood levels were monitored during treatment and up to 4 weeks thereafter. MAIN FINDINGS: FTY720 administered p.o. in baboons at 0.3 mg/kg/day caused a marked decrease in circulating lymphocytes within 4 h of treatment, reaching 60-80% decrease within 24-48 h. The effect of FTY720 was seen both on T- and B cells, although it was slightly more rapid/pronounced on T cells. CD4+ cells were slightly more affected than CD8+ cells. The response onset was faster and the duration longer at higher dose, but the maximal peripheral lymphodepletion achieved was similar within the dose range 0.03-0.3 mg/kg tested. Ex vivo mitogen-induced lymphoproliferation was drastically decreased after FTY720 treatment, corresponding to the reduced blood lymphocyte counts. The blood drug levels measured after FTY720 administration correlated well with the dose applied but there was a poor correlation between FTY720 blood levels and the extent of peripheral lymphodepletion, suggestive of a high tissue distribution of the drug. When compared with cynomolgus monkeys treated in the same way, baboons had a lower initial exposure and a slightly lower response 24 h after one or two doses of FTY720 0.03-0.3 mg/kg. However, the stabilized drug blood levels and peripheral lymphodepletion achieved after 7 days of FTY720 0.03 mg/kg/day were similar in both nonhuman primate species. CONCLUSIONS: FTY720 was well tolerated and was effective in terms of peripheral T- and B lymphodepletion in baboons, indicating that it could be used in protocols of allo- and xenotransplantation. The pharmacokinetic and pharmacodynamic profiles of FTY720 in baboons suggest the use of high induction doses to optimize immediate response followed by a reduced dose regimen for drug maintenance.

Animals↗
PubMed1998

Potent inhibition of CTLA-4 expression by an anti-CTLA-4 ribozyme.

Blockading the negative-regulatory CTLA-4 receptor has emerged as a powerful strategy with clinical potential to enhance T-cell responses. Some experimental tumors, for example, are rejected when anti-CTLA-4 antibodies are administered in vivo. The concise target cells and downstream events, however, remain to be defined. The development of gene transfer reagents that inhibit CTLA-4 may facilitate such investigations and may expand the therapeutic range. This communication describes an anti-CTLA-4 hairpin ribozyme that specifically abrogates CTLA-4 expression after gene transfer into a murine T-cell model. The analysis of multiple and independently derived clones and bulk cultures showed that CTLA-4 induction was inhibited > 90% at the RNA level and that it was undetectable at the protein level, with and without selective pressure. This potent inhibition required the catalytic function of the ribozyme. The anti-CTLA-4 ribozyme may be an alternative tool with which to continue the functional and therapeutical exploration of CTLA-4.

Abatacept↗
PubMed1998

A minimally replicative HIV-2 live-virus vaccine protects M. nemestrina from disease after HIV-2(287) challenge.

M. nemestrina immunized with an apathogenic HIV-2 molecular clone (HIV-2KR) were protected from CD4 decline and disease upon challenge with HIV-2(287), after any immunizing virus could be detected. Higher but not lower inocula of HIV-2KR were protective against intravenous inoculation of either 10(5) or 10(1) TCID50 of HIV-2(287). Protected animals displayed substantial reductions in PBMC proviral burden (1-3 logs), viral titers (1-2 logs), and plasma viral RNA (2-4 logs) compared to unprotected or naive animals as early as 1 week postinfection. Plasma viral RNA became undetectable after 24 weeks in protected animals, but remained high in unprotected animals. No viral RNA was present in the spleen of the protected animal necropsied more than a year after challenge (though viral DNA was still present). No neutralizing responses could be demonstrated, but CTL activity was detected sooner and at higher levels after challenge in protected than in unprotected macaques. In this novel HIV-2 vaccine model, protection was clearly dose-dependent, and clearance of challenge virus RNA from the plasma did not require detectable ongoing replication of the immunizing virus at the time of challenge.

AIDS Vaccines↗
PubMed1998

Characterization of a molecular clone of HIV type 2 infectious for Macaca nemestrina.

A lambda phage clone containing a full-length HIV-2 provirus, designated HIV-2KR, was obtained from the genomic DNA of Molt4 clone 8 (Molt4/8) lymphoblastic cells infected with the HIV-2PEI2 strain. HIV-2KR is genetically distinct from known HIV-2 isolates, possessing both a unique deletion in the LTR promoter region, and a long rev reading frame. It is replication competent in vitro after transfection into Molt4/8 cells, replicates in a variety of established human T lymphoblastic (Molt-3, Molt4/8, SupT1, H9, C8166) and myelomonocytic (U937) cell lines, and displays prominent cytopathic effects on infection of Molt4/8 cells, reflecting usage of both CCR5 and CXCR4 coreceptors. In addition, HIV-2KR was found to be infectious for human and Macaca nemestrina peripheral blood lymphocytes, and primary human monocyte-macrophage cultures. Intravenous inoculation of cell-free virus into M. nemestrina resulted in infection characterized by transient, low-level viremia and modest temporary decline in CD4 lymphocyte numbers, making HIV-2KR the first HIV-2 molecular clone reported to be infectious for this primate species.

Amino Acid Sequence↗
PubMed1998

[Propofol for anesthesia and short-term sedation. The final word on use in children under three years].

Since its introduction in clinical use more than ten years ago, propofol is well appreciated for sedation and supplemental hypnosis in anaesthesia. However the substance is approved only for anaesthesia in children elder than three years. As can be substantiated by many data reported in literature, there are no pharmacokinetic or pharmacodynamic reasons whatsoever to withhold propofol from the younger children; this applies both to the use as a narcotic supplement and as a short term hypnotic for diagnostic and therapeutic interventions.

Anesthetics, Intravenous↗
PubMed1998

Optimization of an effervescent tablet formulation containing spray dried L-leucine and polyethylene glycol 6000 as lubricants using a central composite design.

A rotatable central composite design is used to evaluate the effects of lubricants and compression force on the physical characteristics of effervescent tablets. Effervescent tablets lubricated with a combination of spray dried L-leucine and polyethylene glycol 6000 are prepared by direct compression and examined. Residual force, crushing strength and disintegration time are considered as response variables and related to the L-leucine and polyethylene glycol concentrations and to the compression force. The calculated models are used to assess the influence of the production factors on tablet properties. As increasing amounts of L-leucine, showing good lubricating properties, reduce the crushing strength and prolong tablet disintegration, the L-leucine concentration is kept at a low level. An optimum tablet formulation contains 2% L-leucine and 3% polyethylene glycol 6000. The tablets have a tensile strength of 0.47 MPa and disintegrate in less than 2 min. Predicted and experimental results are in agreement within a 95% CI.

Chemistry, Pharmaceutical↗
PubMed1998

Transduction of human macrophages using a stable HIV-1/HIV-2-derived gene delivery system.

We have previously established a stable HIV-1 packaging cell line, psi 422, which yielded high titers of an HIV-1 vector capable of efficiently transducing CD4+ cells. In order to increase the safety of this gene delivery system, we have now replaced the HIV-1 vector with an HIV-2 vector to abolish any risk of homologous recombination between the packaging cells and the vector. The HIV-2 vector was also modified by insertion of a cis-acting constitutive transport element which confers Rev independence. The supernatant of psi 422 cells stably transfected with this new vector was capable of transducing CD4+ cells with a titer of 10(4) transducing units per milliliter. This result shows that cross-packaging of HIV-2 vectors with the HIV-1 packaging cells is quite efficient. Using this new stable HIV-1/HIV-2 gene delivery system, we were able to transduce human monocyte-derived primary macrophages, which are refractory to murine retrovirus-mediated transduction. The availability of a stable HIV-based gene delivery system for macrophages, a key target cell in HIV infection; is an important advance in gene therapy for AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Genetic variation in a human immunodeficiency virus type 2 live-virus Macaca nemestrina vaccine model.

Four pigtailed macaques were inoculated with an infectious, apathogenic human immunodeficiency virus type 2 (HIV-2) molecular clone (HIV-2KR) and subsequently challenged with a highly pathogenic strain, HIV-2287, together with two naive control animals. After challenge, two animals inoculated with a high dose of the immunizing strain were protected from CD4 decline and immunodeficiency. To examine the role of genetic heterogeneity in protection, fragments of the env gene were amplified from peripheral blood mononuclear cell DNA and plasma RNA of challenged animals by PCR, examined by using a heteroduplex tracking assay (HTA), and sequenced. By HTA, variation was detected principally within the V1 and V2 regions of envelope. Extent of variation in viral DNA clones as assessed by HTA correlated with inoculum size, as did the degree of variation in sequences of clones derived from viral DNA. Conversely, a rapid reduction in the number of plasma viral RNA variants was noted by HTA at 8 weeks postinfection in protected animals; this reduction was not present in naive or unprotected macaques. Sequences derived from plasma viral RNA were found to be more closely related than corresponding viral DNA sequences, and protection correlated with a significant reduction in variation in plasma RNA sequences in animals given the identical inocula of HIV-2287. Nonsynonymous mutations were significantly less prevalent in the protected animals. An additional potential glycosylation site was predicted to be present in the V2 region in all but one clone, and amino acid signatures related to protection were identified in viral DNA and RNA clones within both the V1 and V2 regions. Examination of the role of viral variation in this HIV-2 live-virus vaccine model may provide valuable insights into immunopathogenesis.

Amino Acid Sequence↗
PubMed1997

Intracellular immunization of rhesus CD34+ hematopoietic progenitor cells with a hairpin ribozyme protects T cells and macrophages from simian immunodeficiency virus infection.

Evaluation of candidate genes for stem cell gene therapy for acquired immunodeficiency syndrome (AIDS) has been limited by the difficulty of supporting in vitro T-cell differentiation of genetically modified hematopoietic progenitor cells. Using a novel thymic stromal culture technique, we evaluated the ability of a hairpin ribozyme specific for simian immunodeficiency virus (SIV) and human immunodeficiency virus type 2 (HIV-2) to inhibit viral replication in T lymphocytes derived from transduced CD34+ progenitor cells. Retroviral transduction of rhesus macaque CD34+ progenitor cells with a retroviral vector (p9456t) encoding the SIV-specific ribozyme and the selectable marker neomycin phosphotransferase in the presence of bone marrow stroma and in the absence of exogenous cytokines resulted in efficient transduction of both colony-forming units and long-term culture-initiating cells, with transduction efficiencies ranging between 21% and 56%. After transduction, CD34+ cells were cultured on rhesus thymic stromal culture (to support in vitro differentiation of T cells) or in the presence of cytokines (to support differentiation of macrophage-like cells). After expansion and selection with the neomycin analog G418, cells derived from transduced progenitor cells were challenged with SIV. CD4+ T cells derived from CD34+ hematopoietic cells transduced with the ribozyme vector p9456t were highly resistant to challenge with SIV, exhibiting up to a 500-fold decrease in SIV replication, even after high multiplicities of infection. Macrophages derived from CD34+ cells transduced with the 9456 ribozyme exhibited a comparable level of inhibition of SIV replication. These results show that a hairpin ribozyme introduced into CD34+ hematopoietic progenitor cells can retain the ability to inhibit AIDS virus replication after T-cell differentiation and support the feasibility of intracellular immunization of hematopoietic stem cells against infection with HIV and SIV. Protection of multiple hematopoietic lineages with the SIV-specific ribozyme should permit analysis of stem cell gene therapy for AIDS in the SIV/macaque model.

Acquired Immunodeficiency Syndrome↗