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Biomedical subjects

P Vos

Publications and source records attributed to P Vos.

At least 19 recordsLinked to original sources
PubMed2001

Incidence of benign lesions in patients resected for suspicious hilar obstruction.

BACKGROUND: The differentiation between benign and malignant strictures at the hepatic hilum is difficult. The aim of this study was to assess the clinical and radiographical features of hilar lesions in a series of patients resected for a presumed cholangiocarcinoma. METHODS: Of 132 consecutive patients undergoing resection for a suspicious lesion at the hepatic hilum, 20 (15 per cent) had a histopathologically proven benign tumour, diagnosed as chronic fibrosing or erosive inflammation, sclerosing cholangitis, or a granular cell tumour. All medical files and radiological examinations of the patients were reassessed. RESULTS: Clinical symptoms were considered suspicious in 16 of 19 patients. At ultrasonography only one of 16 patients had an unsuspicious examination. In 14 of 18 patients cholangiographic images were considered suspicious. Overall reassessment confirmed a suspicious lesion in all 20 patients. CONCLUSION: Because of the limitations of current diagnostic tools, a false-positive preoperative diagnosis of malignancy resulted in a 15 per cent resection rate of benign lesions in this series of suspicious hilar strictures.

Abdominal Pain↗
PubMed2000

Progress in Arabidopsis genome sequencing and functional genomics.

Arabidopsis thaliana has a relatively small genome of approximately 130 Mb containing about 10% repetitive DNA. Genome sequencing studies reveal a gene-rich genome, predicted to contain approximately 25000 genes spaced on average every 4.5 kb. Between 10 to 20% of the predicted genes occur as clusters of related genes, indicating that local sequence duplication and subsequent divergence generates a significant proportion of gene families. In addition to gene families, repetitive sequences comprise individual and small clusters of two to three retroelements and other classes of smaller repeats. The clustering of highly repetitive elements is a striking feature of the A. thaliana genome emerging from sequence and other analyses.

Agriculture↗
PubMed2000

Autoimmune hemolytic anemia in patients with non-Hodgkin's lymphoma: characteristics and significance.

BACKGROUND: The occurrence of autoimmune hemolytic anemia (AIHA) in patients with non-Hodgkin's lymphoma (NHL) is well known. However, there is lack of information in the literature in terms of the significance and impact of such phenomenon on the clinical course of these patients. PATIENTS AND METHODS: We analyzed the clinical and laboratory features, course and response of 16 patients with non-Hodgkin's lymphoma (NHL) and autoimmune hemolytic anemia (AIHA). Patients with small lymphocytic lymphoma and angioimmunoblastic lymphadenopathy with dysproteinemia were excluded from the analysis. The significance of certain parameters, such as cell type (B- vs. T-cell), stage of NHL and presence of serum monoclonal immunoglobulin were examined. The cohort consisted of 501 patients with NHL evaluated during the study period. RESULTS: The response rate for the group of patients with NHL/AIHA and for the cohort was 44% and 62%, respectively; P = 0.0138. T-cell histology was overrepresented in the patients with AIHA/NHL (33% vs. 14%; P = 0.048). The occurrence of AIHA was not statistically significant among the four stages of NHL (P = 0.722), while a significantly higher proportion of patients with AIHA had serum monoclonol gammopathy when compared to the cohort (25% vs. 8%; P = 0.03). The patients with NHL who did not develop AIHA had better overall survival and median survival compared to the NHL/AIHA group (P = 0.006 and P = 0.0001, respectively). CONCLUSIONS: The study provides for the first time a descriptive clinicopathologic analysis of patients with AIHA and NHL. Certain pathologic and laboratory features were more likely to be associated with the occurrence of AIHA in patients with NHL. Most importantly, was the adverse impact of AIHA on the survival of patients with NHL. Therefore, this finding should be taken in consideration when risk-stratifying patients with NHL.

Adult↗
PubMed2000

Combined preoperative chemotherapy and radiation for locally advanced rectal carcinoma.

To determine the efficacy of combined preoperative chemotherapy and radiation therapy for locally advanced rectal carcinoma and the rate of sphincter conservation, a retrospective survey of 39 patients with locally advanced rectal carcinoma treated with various 5-fluorouracil- and leukovorin-based chemotherapy regimens and radiation prior to surgery in a single institution was reviewed. Toxicity, local control and survival were evaluated and compared to previous studies with similarly staged patients. Long-term follow-up was available on 35 patients. The actuarial local failure was 5.7% while the actuarial 5-year survival was 87%. The mortality rate was low (2.5%) and the rate of long-term serious complications acceptable (11.4%). Combined preoperative chemotherapy and radiation provided excellent local regional control despite the poor prognostic factors associated with size, fixation, and the initial advanced tumor stage with acceptable morbidity. In addition, patients with tumors located in the lower third of the rectum may be able to undergo sphincter-sparing surgery. Although the median follow-up is relatively short (32.4 months), the results are in accordance with previous studies of neoadjuvant combined chemotherapy and radiation for locally advanced rectal carcinoma in terms of local and distant control.

Anal Canal↗
PubMed2000

Release of glial tissue-specific proteins after acute stroke: A comparative analysis of serum concentrations of protein S-100B and glial fibrillary acidic protein.

BACKGROUND AND PURPOSE: This study was aimed at the comparative analysis of serum concentrations of glial fibrillary acidic protein (GFAP) and protein S-100B in patients with acute stroke. METHODS: We investigated 32 patients with stroke symptoms consistent with cerebral ischemia in the anterior territory of vascular supply. Serial venous blood samples were taken after admission to the hospital and during the first 4 days after onset of stroke. Evaluation of lesion topography and volume of infarcted brain area was based on cranial CT data. The patients' clinical status was consecutively evaluated by the National Institutes of Health Stroke Scale (NIHSS) and the Barthel Index score at discharge from the hospital. RESULTS: Protein S-100B and GFAP release was found to be significantly correlated (r=0.96; P:<0.001). The release of both biochemical markers was associated with the volume of brain lesions (S-100B: r=0.957, P:<0.0001; GFAP: r=0.955, P:<0.0001) and the neurological status at discharge from the hospital (S-100B: r=0.821, P:=0.0002; GFAP: r=0.717, P:=0.0003). The highest correlation between both S-100B and GFAP serum concentration and Barthel score was calculated at the last time of blood sampling, 4 days after stroke onset (S-100B: r=0.621, P:<0.001; GFAP: r=0.655, P:<0.001). The release of both astroglia derived proteins differed between different subtypes of stroke. GFAP was found to be a more sensitive marker of brain damage in patients with smaller lacunar lesions or minor strokes. CONCLUSIONS: Our results indicate that postischemic release patterns of GFAP and S-100B protein may allow insight into the underlying pathophysiology of acute cerebral infarcts and may be used as a valuable tool of clinical stroke treatment.

Acute Disease↗
PubMed1999

Sequence and analysis of chromosome 4 of the plant Arabidopsis thaliana.

The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the sequence of chromosome 4. Analysis of 17.38 megabases of unique sequence, representing about 17% of the genome, reveals 3,744 protein coding genes, 81 transfer RNAs and numerous repeat elements. Heterochromatic regions surrounding the putative centromere, which has not yet been completely sequenced, are characterized by an increased frequency of a variety of repeats, new repeats, reduced recombination, lowered gene density and lowered gene expression. Roughly 60% of the predicted protein-coding genes have been functionally characterized on the basis of their homology to known genes. Many genes encode predicted proteins that are homologous to human and Caenorhabditis elegans proteins.

Animals↗
PubMed1999

Effect of cyclosporine on mycophenolic acid trough levels in kidney transplant recipients.

BACKGROUND: Triple drug treatment consisting of mycophenolate mofetil (MMF), in a standard dose of 2 g daily, combined with cyclosporine (CsA) and prednisone, has become the standard immunosuppressive regimen after kidney transplantation in many centers. The need for therapeutic drug monitoring of mycophenolic acid (MPA) has not yet been established. Several drug interactions with MMF are known. We investigated the influence of CsA withdrawal on MPA trough levels in renal transplant patients. METHODS: Fifty-two patients were treated with 1 g of MMF twice daily, and prednisone and CsA targeted between 125 and 175 ng/ml for 6 months after transplantation. At 6 months after transplantation, 19 patients were randomized for continuation of triple therapy (group A), 19 patients discontinued CsA (group B), and 14 patients discontinued prednisone (group C). We compared 12-hr fasted MPA trough levels at 6 and 9 months after transplantation within and between these groups. RESULTS: MPA trough levels during treatment with CsA, MMF, and prednisone were significantly lower than those during treatment with MMF and prednisone only (group B); median levels were 1.87 mg/L (range: 0.56-5.27) vs. 3.16 mg/L (range: 0.32-7.78), respectively (P=0.002). MPA trough levels in groups A and C did not change between 6 and 9 months after transplantation; group A median levels were 1.87 (range: 0.31-4.32) vs. 1.53 mg/L (range: 0.36-3.70), and group C median levels were 1.62 (range: 0.69-10.34) vs. 1.79 mg/L (range: 0.54-6.00), respectively. At 9 months after transplantation, patients in whom CsA was discontinued had higher MPA trough levels as compared with patients who continued the use of triple therapy (P=0.001) or patients in whom steroids were withdrawn (P=0.014). CONCLUSION: A significant increase of MPA trough levels was found after discontinuation of CsA (6 months after transplantation), resulting in almost a doubling of MPA trough levels at 9 months after transplantation. This resulted in increased MPA levels in patients without CsA as compared to MPA levels in patients continuing triple therapy or discontinuing prednisone.

Cyclosporine↗
PubMed1999

Evidence for an ancient chromosomal duplication in Arabidopsis thaliana by sequencing and analyzing a 400-kb contig at the APETALA2 locus on chromosome 4.

As part of the European Scientists Sequencing Arabidopsis program, a contiguous region (396607 bp) located on chromosome 4 around the APETALA2 gene was sequenced. Analysis of the sequence and comparison to public databases predicts 103 genes in this area, which represents a gene density of one gene per 3.85 kb. Almost half of the genes show no significant homology to known database entries. In addition, the first 45 kb of the contig, which covers 11 genes, is similar to a region on chromosome 2, as far as coding sequences are concerned. This observation indicates that ancient duplications of large pieces of DNA have occurred in Arabidopsis.

Arabidopsis↗
PubMed1999

Leukocyte depletion during cardiac operation: a new approach through the venous bypass circuit.

BACKGROUND: Leukocyte depletion recently has been introduced for cardiac surgical patients to attenuate leukocyte-mediated inflammation and organ reperfusion injury. We evaluated the feasibility of a new leukocyte depletion method in which systemic leukocyte depletion is achieved through the venous side of the cardiopulmonary bypass circuit under low blood flow. METHODS: Forty cardiac surgical patients undergoing cardiopulmonary bypass were allocated randomly to a leukocyte depletion group (n = 20) and a control group (n = 20). In the depletion group, leukocyte filtration was achieved with two filter sets located between the venous drainage and the venous reservoir. Leukocyte filtration was commenced after the start of rewarming but before the release of the aortic cross-clamp, and it was driven by a spare roller pump of the heart-lung machine. RESULTS: All the episodes of filtration went smoothly within a period of 10 minutes and with a blood flow rate of 400 mL/min. The mean leukocyte removal rate calculated at the end of filtration was 69%. Circulating leukocytes were reduced by 38% in the depletion group compared with the control group at the moment of cross-clamp release (4.3x10(9)/L versus 6.8x10(9)/L, p<0.05). The postoperative inflammatory response also was reduced as indicated by less production of interleukin-8 (p<0.05). Clinically, there was no significant difference between the two groups in postoperative PaO2 or pulmonary hemodynamics. CONCLUSIONS: It is technically feasible to deplete circulating leukocytes through the venous side of the cardiopulmonary bypass circuit with a low blood flow rate. Future studies should focus on the duration and timing of leukocyte depletion to optimize the methodology of leukocyte depletion for cardiac surgical patients.

Aged↗
PubMed1999

Hepatosplenic candidiasis in patients with acute leukaemia.

A retrospective study of 23 patients with acute leukaemia and hepatosplenic candidiasis (HSC) was conducted to evaluate clinical treatment characteristics in terms of amount and duration of antifungal agents and to assess treatment outcome. Patients were admitted to two major tertiary care centres between 1990 and 1998. The diagnosis of HSC was based on clinical, blood cultures, histologic and imaging studies. Patients were treated with amphotericin B without interruption of the planned chemotherapy regimens. Serial magnetic resonance imaging (MRI) studies were the main tool for following patients' response and activity of the fungal lesions in conjunction with clinical and laboratory parameters. Treatment with amphotericin B was continued until resolution of all clinical symptoms and signs attributable to HSC, obtaining negative blood cultures and the appearance of at least healed lesions on MRI. Amphotericin B was discontinued in four patients because of severe nephrotoxicity (two patients), or continuous fever and persistent fungal lesions on MRI (two patients). Amphotericin B lipid complex (ABELCET) was successfully used as salvage therapy for these refractory patients. Four patients died with evidence of HSC despite treatment and supportive measures. The response rate for treatment of HSC was 82%. The mean total dose of amphotericin B including empirical treatment was 4 g and the median duration of treatment for responding patients was 112 d. The median number of days of anti- fungal treatment before the disappearance of fever was 19 d. Our results confirmed the need for protracted courses of antifungal agents for the successful eradication of HSC. Chemotherapy for the underlying disorder should not be interrupted or delayed in order to treat HSC.

Acute Disease↗
PubMed1998

Genetic and physical localization of the root-knot nematode resistance locus mi in tomato.

As part of a map-based cloning strategy designed to isolate the root-knot nematode resistance gene Mi, tomato F2 populations were analyzed in order to identify recombination points close to this economically important gene. A total of 21,089 F2 progeny plants were screened using morphological markers. An additional 1887 F2 were screened using PCR-based flanking markers. Fine-structure mapping of recombinants with newly developed AFLP markers, and RFLP markers derived from physically mapped cosmid subclones, localized Mi to a genomic region of about 550 kb. The low frequency of recombinants indicated that recombination was generally suppressed in these crosses and that crossovers were restricted to particular regions. To circumvent this problem, a population of Lycopersicon peruvianum, the species from which Mi was originally introgressed, that was segregating for resistance was developed. Screening of this population with PCR, RFLP and AFLP markers identified several plants with crossovers near Mi. Recombination frequency was approximately eight-fold higher in the Mi region of the L. peruvianum cross. However, even within the wild species cross, recombination sites were not uniformly distributed in the region. By combining data from the L. esculentum and L. peruvianum recombinant analyses, it was possible to localize Mi to a region of the genome spanning less than 65 kb.

Animals↗
PubMed1998

The tomato Mi-1 gene confers resistance to both root-knot nematodes and potato aphids.

Mi-1, a Lycopersicon peruvianum gene conferring resistance to the agricultural pests, root-knot nematodes, and introgressed into tomato, has been cloned using a selective restriction fragment amplification based strategy. Complementation analysis of a susceptible tomato line with a 100 kb cosmid array yielded a single cosmid clone capable of conferring resistance both to the root-knot nematode Meloidogyne incognita and to an unrelated pathogen, the potato aphid Macrosiphum euphorbiae. This resistance was stable. The Mi-1 gene encodes a protein sharing structural features with the nucleotide-binding site leucine-rich repeat-containing type of plant resistance genes.

Amino Acid Sequence↗
PubMed1998

Dissection of the fusarium I2 gene cluster in tomato reveals six homologs and one active gene copy.

The I2 locus in tomato confers resistance to race 2 of the soil-borne fungus Fusarium oxysporum f sp lycopersici. The selective restriction fragment amplification (AFLP) positional cloning strategy was used to identify I2 in the tomato genome. A yeast artificial chromosome (YAC) clone covering approximately 750 kb encompassing the I2 locus was isolated, and the AFLP technique was used to derive tightly linked AFLP markers from this YAC clone. Genetic complementation analysis in transgenic R1 plants using a set of overlapping cosmids covering the I2 locus revealed three cosmids giving full resistance to F. o. lycopersici race 2. These cosmids shared a 7-kb DNA fragment containing an open reading frame encoding a protein with similarity to the nucleotide binding site leucine-rich repeat family of resistance genes. At the I2 locus, we identified six additional homologs that included the recently identified I2C-1 and I2C-2 genes. However, cosmids containing the I2C-1 or I2C-2 gene could not confer resistance to plants, indicating that these members are not the functional resistance genes. Alignments between the various members of the I2 gene family revealed two significant variable regions within the leucine-rich repeat region. They consisted of deletions or duplications of one or more leucine-rich repeats. We propose that one or both of these leucine-rich repeats are involved in Fusarium wilt resistance with I2 specificity.

Amino Acid Sequence↗
PubMed1998

Perceptual grouping of strip dot patterns.

Grouping of one-dimensional (strip) dot patterns was investigated, using an adjustment procedure to evaluate the distance (adjusted gap) at which two patterns appear to merge in a single strip. The size of the patterns had only a scaling effect on the adjusted gap. The adjusted gap and the variance of the estimates were influenced by the number of dots and the regularity (similarity, symmetry) of the patterns in the pair. Models of proximal grouping failed to account for the results obtained. A two-stage process implying determination of dot location and evaluation of inter-dot separation by means of "eclectic units" (Morgan, Hole & Glennerster, 1990) was considered to explain the findings.

Adult↗
PubMed1997

AFLP-based fine mapping of the Mlo gene to a 30-kb DNA segment of the barley genome.

Resistance of barley (Hordeum vulgare) to the powdery mildew fungus Erysiphe graminis f.sp. hordei is conferred by several dominant genes, but also by recessive alleles of the Mlo locus mapping on the long arm of chromosome 4. In addition, this single-factor-mediated resistance is active against all known physiological races of the parasite. Thus the mechanism underlying mlo-mediated resistance should differ substantially from that mediated by the dominant genes. A positional cloning strategy to isolate the Mlo gene from the barley genome, the size of which is almost double the size of the human genome, has been designed. The AFLP technique was employed to identify markers tightly linked to the Mlo locus and to produce a local high-resolution genetic map. The use of this high-volume marker technology allowed the rapid screening of approximately 250,000 loci for linkage to Mlo. A large number of Mlo-linked AFLP markers were identified, one of which cosegregated with Mlo on the basis of more than 4000 meiotic events. A four-genome-equivalent barley YAC library (average insert size 480 kb) was constructed and screened with this cosegregating marker. Four YACs containing this marker were isolated and subsequent characterization by AFLP-based physical mapping allowed the physical delimitation of the Mlo locus to a DNA segment of 30 kb.

Chromosome Mapping↗