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A Jacobs

Publications and source records attributed to A Jacobs.

At least 73 records · Page 4Linked to original sources
PubMed1999

HSV-1-based vectors for gene therapy of neurological diseases and brain tumors: part II. Vector systems and applications.

Many properties of HSV-1 are especially suitable for using this virus as a vector to treat diseases affecting the central nervous system (CNS), such as Parkinson's disease or malignant gliomas. These advantageous properties include natural neurotropism, high transduction efficiency, large transgene capacity, and the ability of entering a latent state in neurons. Selective oncolysis in combination with modulation of the immune response mediated by replication-conditional HSV-1 vectors appears to be a highly promising approach in the battle against malignant glioma. Helper virus-free HSV/AAV hybrid amplicon vectors have great promise in mediating long-term gene expression in the PNS and CNS for the treatment of various neurodegenerative disorders or chronic pain. Current research focuses on the design of HSV-1-derived vectors which are targeted to certain cell types and support transcriptionally regulatable transgene expression. Here, we review the recent developments on HSV-1-based vector systems and their applications in experimental and clinical gene therapy protocols.

Brain Neoplasms↗
PubMed1999

The DNA sequences of T-DNA junctions suggest that complex T-DNA loci are formed by a recombination process resembling T-DNA integration.

After Agrobacterium-mediated plant transformation, multiple T-DNAs frequently integrate at the same position in the plant genome, resulting in the formation of inverted and direct repeats. Because these inverted repeats cannot be amplified and analyzed by PCR, Arabidopsis root cells were co-transformed with two different T-DNAs with distinct sequences adjacent to the T-DNA borders. Nine direct or inverted T-DNA border junctions were analyzed at the sequence level. Precise end-to-end fusions were found between two right border ends, whereas imprecise fusions and filler DNA were present in T-DNA linkages containing a left border end. The results suggest that end-to-end ligation of double-stranded T-DNAs occurs especially between right T-DNA ends and that illegitimate recombination on the basis of microhomology, deletions, repair activities and insertions of filler DNA is involved in the formation of left border T-DNA junctions. Therefore, a similar illegitimate recombination mechanism is proposed that is involved in the formation of complex T-DNA inserts as well as in the integration of the T-DNA in the plant genome.

Agrobacterium tumefaciens↗
PubMed1999

High level accumulation of single-chain variable fragments in the cytosol of transgenic Petunia hybrida.

The accumulation of five murine single-chain variable fragments, binding to dihydroflavonol 4-reductase, was analyzed in transgenic Petunia hybrida plants. The five scFv-encoding sequences were cloned in an optimized plant transformation vector for expression in the cytosol under control of the 35S promoter. In a transient expression assay we found that the scFv expression levels were reproducible and correlated with those in stably transformed petunia. Our results show that accumulation in the cytosol strongly depends on the intrinsic properties of the scFv fragment. Three of the five scFv fragments accumulated to unexpectedly high levels in the cytosol of the primary transformants, but no phenotypic effect could be detected. Experimental results indicate that one of the scFv fragments accumulated in the cytosol to 1% of the total soluble protein as a functional antigen-binding protein in the absence of disulphide bonds. This observation supports the idea that certain antibody fragments do not need disulphide bonds to be stable and functional. Such scFv scaffolds provide new opportunities to design scFv fragments for immunomodulation in the cytosol.

Alcohol Oxidoreductases↗
PubMed1999

Optimizing electrode sites for segmental bioimpedance measurements.

Recent advances in the application of bioelectrical impedance analysis (BIA) have indicated that a more accurate approach to the estimation of total body water is to consider the impedance of the various body segments rather than simply that of the whole body. The segmental approach necessitates defining and locating the physical demarcation between both the trunk and leg and the trunk and arm. Despite the use of anatomical markers, these points of demarcation are difficult to locate with precision between subjects. There are also technical problems associated with the regional dispersion of the current distribution from one segment (cylinder) to another of different cross-sectional area. The concept of equipotentials in line with the proximal aspects of the upper (and lower) limbs along the contralateral limbs was investigated and, in particular, the utility of this concept in the measurement of segmental bioimpedance. The variation of measured segmental impedance using electrode sites along these equipotentials was less than 2.0% for all of the commonly used impedance parameters. This variation is approximately equal to that expected from biological variation over the measurement time. It is recommended that the electrode sites, for the measurement of segmental bioelectrical impedance in humans, described herein are adopted in accordance with the proposals of the NIH Technology Assessment Conference Statement.

Arm↗
PubMed1999

Functional magnetic resonance imaging and radiosurgical dose planning.

OBJECTIVE: To assess the effect of functional magnetic resonance imaging (fMRI) on stereotactic radiosurgical (SRS) dose planning. METHODS: Patients included those undergoing SRS whose lesions were in or near areas that could be identified with fMRI. After processing, an fMR scan was registered to the anatomic scan, and this dataset was registered to a stereotactic CT scan. The imaged functional areas were contoured along with standard anatomical targets. Dose planning was done at first with the functional volumes rendered invisible; the plans were then adjusted as needed using the functional targets. Doses were measured using a dose-volume histogram tool. RESULTS: SRS was performed in 12 patients, 1 of whom also underwent SRT. Functional volumes studied included motor cortex in 8 patients, visual in 6 and language in 3; a total of 33 functional targets were imaged. Prescription doses ranged from 12 to 22.5 Gy (mean 19.5 Gy), and the maximum dose to functional volumes from 8 cGy to 18.5 Gy (mean 2.9 Gy). In 6 patients, arc adjustment using functional targets yielded a >50% reduction in dose to at least one functional volume; in all patients, the dose reduction to 50 and 75% of functional volumes averaged 4% (12 cGy) and 13% (30 cGy), respectively, while the reduction of maximal dose averaged 24% (50 cGy). CONCLUSIONS: fMRI can be used in SRS to reduce irradiation of eloquent brain using standard prescription doses. Appropriate arc adjustment may allow for escalation of the dose to the targeted lesion.

Adult↗
PubMed1998

Strongly enhanced sensitivity of a direct anti-HIV-1/-2 assay in seroconversion by incorporation of HIV p24 ag detection: a new generation vironostika HIV Uni-Form II.

The clinical sensitivity of the current anti-HIV assays is based for an important part on their reactivity with seroconversion panels. The most sensitive assay closes the seroconversion window as much as possible, thereby reducing the risk of transmitting false negative donations obtained from individuals infected recently. Because of the absence of anti-HIV antibodies during the early phase of infection, the seroconversion window can be narrowed partially by detection of HIV p24 Ag. To achieve this, the highest affinity anti-p24 binding antibodies were selected with BlAcore and applied in a direct assay format. To achieve optimal conditions for the anti-HIV part of the assay the HIV specific antigens viral HIV-1 gp160, HIV-2 gp36 and HIV-1 group O gp41 peptides were used. These antigens and antibodies were applied for microELISA coating as well as in the conjugate pearl, which is present in the well of the microELISA plate. The (analytical) anti-HIV-1/-2 and anti-HIV-1 group O sensitivity of this new assay, Vironostika HIV Uni-Form II Ag/Ab, is at least at the level of the current Vironostika HIV Uni-Form II plus O. When compared to the Vironostika HIV Uni-Form II plus O, the seroconversion window is narrowed by 1-2 weeks due to the incorporation of HIV p24 Ag detection. The level of reactivity of the anti-HIV and HIV Ag detection part can be improved by about a factor 2 by applying continuous shaking during sample incubation. Initial studies suggested that the specificity of the assay is identical to that of the Vironostika HIV Uni-Form II plus O, namely > 99.9%. Monitoring of proper execution of the assay handling steps was facilitated by implementing a purple dye in the conjugate pearl. Colourless specimen diluent changes into a green fluid upon dissolving of the conjugate pearl and turns subsequently into blue/purple upon sample addition. These visual changes can also be determined by spectrophotometric measurement at 620 nm.

Enzyme-Linked Immunosorbent Assay↗
PubMed1998

High-dose busulfan, melphalan and thiotepa followed by autologous peripheral blood stem cell (PBSC) rescue in patients with advanced stage III/IV ovarian cancer.

The purpose of this study was to evaluate the efficacy of high-dose chemotherapy (HDC) with busulfan, melphalan and thiotepa (BUMELTT) followed by autologous PBSC infusion in treating patients with advanced ovarian cancer. Thirty-one patients, 18 with stage III/IIIc and 13 with stage IV ovarian cancer, were treated with BU (12 mg/kg), MEL (100 mg/m2) and TT (500 mg/m2) and autologous PBSC rescue. Fifteen patients were in clinical complete remission (CR) at treatment; 11 had platinum-sensitive disease. Sixteen patients were not in CR; two had platinum-sensitive disease. The probabilities of overall survival (OS), event-free survival (EFS) and relapse (R) for all patients at 18 months were 0.57, 0.30 and 0.63; for patients in CR, the rates were 0.87, 0.44 and 0.49 and for patients not in CR, 0.38, 0.13 and 0.81. Two patients (6.5%) died of treatment-related causes. Among the 13 patients with platinum-sensitive disease, all are still alive, with seven having relapsed 129-1021 days after PBSC infusion. OS, EFS and R were 1.00, 0.52 and 0.48. Of the 18 patients with platinum-resistant disease, four remain alive (two in remission). Six patients did not respond and eight relapsed from days 104-429. The OS, EFS and R were 0.33, 0.11 and 0.78. We conclude that BUMELTT is well tolerated in patients with advanced ovarian cancer and results are equivalent to other published HDC regimens.

Adult↗
PubMed1998

Nonimmune hydrops fetalis due to congenital syphilis associated with negative intrapartum maternal serology screening.

We present an unusual case, in which a woman presenting with markedly decreased fetal movements at 29 weeks gestation following a recent increase in fundal height was noted sonographically to have fetal hydrops consisting of scalp edema, marked hepatomegaly, ascites, and polyhydramnios. No lethal structural congenital anomaly was noted. Admission laboratory examinations revealed a negative antibody screen and a negative RPR. Emergent cesarean section was performed due to prolonged fetal bradycardia during biophysical profile testing. The acidotic hydropic neonate weighing 1825 g was resuscitated yet succumbed at 3 hr of life following intravenous administration of antibiotics. Neonatal blood was RPR positive at 1:16. Postmortem pathology examination demonstrated severe multiorgan system failure secondary to overwhelming congenital syphilis. Extensive extramedullary hematopoiesis was noted and histopathology with Dieterle stains revealed numerous hepatic spirochetes. Postpartum reexamination of the maternal blood with serial dilutions revealed a positive RPR at 1:1024. This case emphasizes that initial negative screening for syphilis may be seen despite overwhelming infection, a condition that has been termed the "prozone effect."

Adult↗
PubMed1998

Agrobacterium tumefaciens transformation and cotransformation frequencies of Arabidopsis thaliana root explants and tobacco protoplasts.

In view of the recent finding that different T-DNAs tend to ligate and integrate as repeats at single chromosomal positions, the frequency of transformation and cotransformation was determined during cocultivation of Arabidopsis thaliana root explants and Nicotiana tabacum protoplasts with two Agrobacterium strains. The transformation frequency of unselected A. thaliana shoots was lower than 1% whereas that of cocultivated tobacco protoplasts was approximately 18%. The cotransformation frequencies, defined as the frequencies with which cells transformed with a first T-DNA contained a second unselected T-DNA, were approximately 40% reproducible, irrespective of the selection, the transformation frequency, and the plant system used. Extrapolation of these results suggests that at least two independently transferred T-DNAs were present in 64% of the transformed plant cells. Molecular analysis of cocultivated N. tabacum shoots regenerated on nonselective medium showed that only a few transformants had a silenced (2/46) or truncated (1/46) T-DNA. Therefore, most integrated T-DNAs expressed their selectable or screenable markers in primary transgenic plants. Remarkably, 10 to 30% of the selected A. thaliana shoots or progenies lost the T-DNA marker they were selected on. As these regenerants contained the unselected T-DNA with a high frequency (17%), these selected plants might result from the expression of unstable, transiently expressed T-DNAs. In conclusion, a significant part of the T-DNAs is lost from the transformed cells.

Agrobacterium tumefaciens↗
PubMed1998

The conjugal intermediate of plasmid RSF1010 inhibits Agrobacterium tumefaciens virulence and VirB-dependent export of VirE2.

Agrobacterium tumefaciens causes crown gall disease by transferring oncogenic, single-stranded DNA (T strand), covalently attached to the VirD2 protein, across the bacterial envelope into plant cells where its expression results in tumor formation. The single-stranded DNA binding protein VirE2 is also transferred into the plant cell, though the location at which VirE2 interacts with the T strand is still under investigation. The movement of the transferred DNA and VirE2 from A. tumefaciens to the plant cell depends on the membrane-localized VirB and VirD4 proteins. Further, the movement of the IncQ broad-host-range plasmid RSF1010 between Agrobacterium strains or from Agrobacterium to plants also requires the virB-encoded transfer system. Our earlier studies showed that the presence of the RSF1010 plasmid in wild-type strains of Agrobacterium inhibits both their virulence and their capacity to transport VirE2, as assayed by coinfection with virE mutants. Here we demonstrate that the capacity to form a conjugal intermediate of RSF1010 is necessary for this inhibition, suggesting that the transferred form of the plasmid competes with the VirD2-T strand and/or VirE2 for a common export site.

Agrobacterium tumefaciens↗
PubMed1998

Alterations of neuropsychological function and cerebral glucose metabolism after cardiac surgery are not related only to intraoperative microembolic events.

BACKGROUND AND PURPOSE: High-intensity transient signals (HITS) during cardiac surgery are capable of causing encephalopathy and cognitive deficits. This study was undertaken to determine whether intraoperative HITS cause alterations of neuropsychological function (NPF) and/or cerebral glucose metabolism (CMRGlc), even in a low-risk patient group, and whether induced changes are interrelated. METHODS: Eighteen patients without signs of cerebrovascular disease underwent elective coronary artery bypass grafting (CABG), and two of these additionally underwent valve replacement in normothermia. Intraoperatively, HITS were recorded by means of transcranial Doppler ultrasonography (TCD). Perioperatively, NPF and CMRGlc were assessed using a standardized complex test battery and positron emission tomography with 18F-2-fluoro-2-deoxy-D-glucose (FDG-PET), respectively. RESULTS: Intraoperatively, the number of HITS ranged from 90 to 1710 per patient and hemisphere, more on the right side than on the left (P<.05). HITS occurred primarily during cardiopulmonary bypass (71.3%) and, to a lesser extent, during aortic manipulation (22.2%). Changes in global and regional CMRGlc between first (one day preoperatively) and second (8 to 12 days postoperatively) FDG-PET scans were mild. No correlations were found between the number of HITS, age of patient, duration of cardiac ischemia or cardiopulmonary bypass and the changes in CMRGlc. In patients with recorded HITS and a postoperative decrease of regional CMRGlc (n=11), the maximal decrease of rCMR Glc in each hemisphere below the individual global change of CMRGlc correlated with the number of HITS (r= -0.46, P<.05). Limitations in NPF occurred 8 to 12 days postoperatively, resolved within 3 months, and were not found to be correlated to the absolute number of HITS or changes in CMRGlc. CONCLUSIONS: HITS during cardiac surgery can cause alterations of both NPF and CMRGlc, even in a low-risk patient group. However, the number of HITS and changes in NPF and CMRGlc are not necessarily interrelated, which indicates that (1) the location of brain damage related to HITS is more important for the development of NPF than is the absolute number of HITS, and (2) factors in addition to HITS might contribute to surgery-related brain damage.

Adult↗
PubMed1998

Seeing difference: market health reform in Europe.

The comparative literature on health care reform has identified a convergence upon market models as nations respond to similar economic, technological, social, and demographic pressures. In this article I first challenge the conventional view by comparing "market" reforms of the late 1980s and early 1990s in the United Kingdom, the Netherlands, and Sweden. Though these nations did indeed converge upon the instrument of the market incentive, there was considerable divergence in the content and aims of their reform strategies. These nations designed their respective markets to make different tradeoffs among competing values. While all three exploited the principle of provider competition, they appointed different actors to judge the contest: the cost-conscious public authority in the United Kingdom, the quality-conscious patient in Sweden, and the optimizing consumer in the Netherlands. I argue that these countries were thus using common market tools to promote different health policy goals. Distinguishing these reforms further is the fact that--particularly in the Netherlands--there was a gap between market plans and the reality of implemented change. I then ask why nations responded so differently to such similar objective pressures. My contention is that this divergence reflects, in part, the different ideological orientations of the ruling party or coalition in each nation. Yet divergence is also the result of differences in both the design of political institutions and the structure of the pre-reform health system in each country.

Economic Competition↗
PubMed1997

Green fluorescent protein as a reporter for retrovirus and helper virus-free HSV-1 amplicon vector-mediated gene transfer into neural cells in culture and in vivo.

Green fluorescent protein (GFP) is an effective marker for retrovirus and herpes virus vector-mediated gene transfer into various central nervous system-derived cells, both proliferative and non-proliferative, in culture and in vivo. Retrovirus vectors were used to stably transduce several rat and human glioma lines, and a multipotent mouse neural progenitor line in culture. Implantation of selected pools of transduced glioma cells into rodent brain allowed clear visualization of the tumor and the invading tumor edge. Helper virus-free HSV-1 amplicon vectors successfully transferred gfp into non-dividing primary neural cells in culture and in the rat brain. This study describes the versatility of GFP for: (i) labelling of glioma cells in experimental brain tumor models and neural progenitor cells by retrovirus vectors, and (ii) efficient, non-toxic delivery of genes to post mitotic cells of the nervous system using helper-virus free HSV-1 amplicon vectors.

Animals↗
PubMed1997

Therapeutic efficiency and safety of a second-generation replication-conditional HSV1 vector for brain tumor gene therapy.

A second-generation replication-conditional herpes simplex virus type 1 (HSV) vector defective for both ribonucleotide reductase (RR) and the neurovirulence factor gamma34.5 was generated and tested for therapeutic safety and efficiency in two different experimental brain tumor models. In culture, cytotoxic activity of this double mutant HSV vector, MGH-1, for 9L gliosarcoma cells was similar to that of the HSV mutant, R3616, which is defective only for gamma34.5, but was significantly weaker than that of the HSV mutant hrR3, which is defective only for RR. The diminished tumoricidal effect of the gamma34.5 mutants could be accounted for by their reduced ability to replicate in 9L cells. The MGH-1 vector did not achieve significant prolongation of survival in vivo in the syngeneic 9L rat gliosarcoma model for either single brain tumor focus or multiple intracerebral and leptomeningeal tumors, when the vector was applied intratumorally or intrathecally, respectively, and with or without subsequent ganciclovir (GCV) treatment. In identical 9L brain tumor models with single and multiple foci, application of hrR3 with or without GCV was previously shown to result in marked long-term survival. Contrary to the findings with intrathecal injection of hrR3, no vector-related mortality was observed in any animals treated with MGH-1. Thus, in these rat brain tumor models, the double mutant, replication-conditional HSV vector MGH-1 showed a higher therapeutic safety than the RR-minus vector, hrR3, but had clearly decreased therapeutic efficiency compared to hrR3. The development of new HSV vectors for brain tumor gene therapy will require a balance between maximizing therapeutic efficacy and minimizing toxicity to the brain. Standardized application in brain tumor models as presented here will help to screen new HSV vectors for these requirements.

Animals↗
PubMed1997

MRI- and MRA-guided therapy of carotid and vertebral artery dissections.

A high sensitivity and specificity has been shown for magnetic resonance imaging (MRI) and angiography (MRA) in the diagnosis of internal carotid (ICAD) and vertebral (VAD) artery dissections, where arteriography has been and still is the gold standard. Five patients (three with ICAD, two with VAD; age range 42-56 years) are presented, in whom diagnosis and follow-up management were exclusively based on non-invasive measures. In all patients, MRI demonstrated a typical intramural hematoma and MRA in 3D phase contrast technique showed loss or diminished flow. After anticoagulation (heparin) for 3 to 4 weeks follow-up, MRI showed a regression of the mural hematoma and MRA revealed reperfusion or improvement of flow. Depending on the extent of MRI-/MRA-pathology, three patients were put on antiplatelet therapy and two on Coumadin until normalization of MRI and MRA findings, which are assessed in 3-months intervals. We suggest, that with, (I) a suspicious history, symptoms and signs for cervical artery dissection (CAD), (II) typical MR-findings proven to indicate CAD, (III) improving or resolving at follow-up, (IV) in unusual location for atherosclerotic involvement, (V) in the absence of coexisting atherosclerotic lesions, the diagnosis has not to be confirmed with conventional arteriography. Therefore, safe MRI- and MRA-guided anticoagulation and antiplatelet therapy during serial follow-up measurements are possible.

Adult↗
PubMed1997

Reactivity of a new HIV-1 group O third generation A-HIV-1/-2 assay with an unusual HIV-1 seroconversion panel and HIV-1 group O/group M subtyped samples.

It was shown previously that about 97% of the anti-HIV-1 group O strain-positive samples were detected by crossreaction with native HIV-1 gp160 (Van Binsbergen et al., Evaluation of a new third generation anti-HIV-1/anti-HIV-2 assay with increased sensitivity for HIV-1 group O, J. Virol. Methods 60 (1996) 131-137). Fourteen out of 17 new anti-HIV-1 group O positive samples, selected with the Enzygnost HIV-1/2 plus assay, were already reactive when tested with HIV-1 gp160. When tested by the Vironostika HIV Uni-Form II plus O microELISA all 17 samples were reactive, demonstrating the necessity to implement an HIV-1 group O-specific antigen in the assay. On the other hand, it was surprisingly found that 40 out of 43 (93%) of anti-HIV-1 group M-positive samples, belonging to strain A, B, C, D, E or F, were detected by crossreaction with the HIV-1 group O (strain ANT70) synthetic peptide incorporated in the Vironostika HIV Uni-Form II plus O. Only HIV-1 subtype D-positive samples did not react with this peptide, presumably because of the presence of a histidine residue in the immunodominant region of HIV-1 subtype D gp41. Both crossreactions make the Vironostika HIV Uni-Form II plus O microELISA also sensitive for anti-HIV-1-positive samples originating from different geographical regions and resulting from different HIV-1 subtype infections. With an unusual seroconversion panel in which p24 Ag was present persistently, many anti-HIV-1/-2 assays produce alternating positive/negative results in anti-HIV antibody-positive bleeds. It was shown that the use of viral p24 and gp160 in a direct sandwich, allowing detection of anti-HIV IgG and IgM, explains the identification of all anti-HIV-positive bleeds by the Vironostika HIV Uni-Form II plus O. The high sensitivity of the plus O assay was confirmed with clinical samples of a so-called anti-HIV-1 low titer panel. The specificity of the Vironostika HIV Uni-Form II plus O determined in five blood transfusion centers, based on 135070 tests, was 99.97%.

AIDS Serodiagnosis↗