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Biomedical subjects

A Weise

Publications and source records attributed to A Weise.

31 records · Page 2Linked to original sources
PubMed2002

Weekly irinotecan in a patient with metastatic colorectal cancer on hemodialysis due to chronic renal failure.

BACKGROUND: The cytotoxic treatment of patients suffering from advanced or metastatic cancer undergoing hemodialysis due to chronic renal failure still remains a problem, since for those patients pharmacokinetic and pharmacodynamic data on most cytotoxic agents are lacking. CASE REPORT: We report a 45-year-old male who suffered from chronic renal failure and was diagnosed with stage-3 colorectal cancer (CRC) in February 2000. After surgical removal of the tumor an adjuvant chemotherapy of dose-reduced i.v. bolus 5-fluorouracil and folinic acid was begun (Mayo protocol). Due to excessive gastrointestinal toxicity, therapy was discontinued after the first cycle. In April 2000 liver metastases were diagnosed. The patient was then put on a weekly schedule of dose-reduced CPT-11 (50 mg/m(2), 80 mg total). No hematological or non-hematological toxicity grade 3/4 was observed. Due to excellent tolerability and lack of severe side effects the dose was increased up to 80 mg/m(2) (140 mg total) weekly. A dose escalation to 100 mg/m(2) (180 mg total) resulted in severe diarrhea (grade 4). Within 2 months of treatment the patient achieved a lasting partial remission until April 2001 (12 months). A significant progression of hepatic metastases required an alternative treatment regimen beginning in July 2001 (HAI, hepatic artery infusion). CONCLUSION: This case report demonstrates the feasibility and efficacy of a weekly treatment with dose-reduced CPT-11 in a patient with metastatic CRC on hemodialysis due to chronic renal failure.

Antineoplastic Agents, Phytogenic↗
PubMed2002

Multicolor chromosome banding (MCB) with YAC/BAC-based probes and region-specific microdissection DNA libraries.

Multicolor chromosome banding (MCB) allows the delineation of chromosomal regions with a resolution of a few megabasepairs, i.e., slightly below the size of most visible chromosome bands. Based on the hybridization of overlapping region-specific probe libraries, chromosomal subregions are hybridized with probes that fluoresce in distinct wavelength intervals, so they can be assigned predefined pseudo-colors during the digital imaging and visualization process. The present study demonstrates how MCB patterns can be produced by region-specific microdissection derived (mcd) libraries as well as collections of yeast or bacterial artificial chromosomes (YACs and BACs, respectively). We compared the efficiency of an mcd library based approach with the hybridization of collections of locus-specific probes (LSP) for fluorescent banding of three rather differently sized human chromosomes, i.e., chromosomes 2, 13, and 22. The LSP sets were comprised of 107 probes specific for chromosome 2, 82 probes for chromosome 13, and 31 probes for chromosome 22. The results demonstrated a more homogeneous coverage of chromosomes and thus, more desirable banding patterns using the microdissection library-based MCB. This may be related to the observation that chromosomes are difficult to cover completely with YAC and/or BAC clones as single-color fluorescence in situ hybridization (FISH) experiments showed. Mcd libraries, on the other hand, provide high complexity probes that work well as region-specific paints, but do not readily allow positioning of breakpoints on genetic or physical maps as required for the positional cloning of genes. Thus, combinations of mcd libraries and locus-specific large insert DNA probes appear to be the most efficient tools for high-resolution cytogenetic analyses.

Chromosome Banding↗
PubMed2002

A novel family-specific translocation t(2;20)(p24.1;q13.1) associated with recurrent abortions: molecular characterization and segregation analysis in male meiosis.

In the present study, we present a novel reciprocal translocation t(2;20)(p24.1;q13.1) and its segregation in a three generation family. The rate of miscarriages (50%) in pregnancies from male translocation carriers could be explained by unbalanced translocation-bearing spermatozoa found with a frequency of approximately 55% in the entire sperm population of a t(2;20)(p24.1;q13.1) carrier. These imbalanced spermatozoa mainly present as 2, der(20) and der(2), 20 missegregated (approximately 46%) while adjacent 2 and 3:1 segregation patterns account for approximately 5% and 4% of imbalances, respectively. While the translocation is associated clearly with an increased risk of early abortions (7/12) in both male and female carriers, no malformed livebirths were observed. Our results suggest complete embryonic lethality of imbalanced offspring. With respect to a high rate of segregation to 2, der(20) and to der(2), 20 imbalanced spermatozoa in male translocation carriers and with respect to known cases of partial trisomy 2p and 20q we consider that their corresponding monosomies result in fetal loss. This is the first study reporting multiple abortions associated with partial monosomy 20q13.1-->qter and 2pter-->p24.1 and the first report on the frequency of chromosomal imbalances in gametes of a male t(2;20)(p24.1;q13.1) heterozygote.

Abortion, Habitual↗
PubMed2002

Comparative M-FISH and CGH analyses in sensitive and drug-resistant human T-cell acute leukemia cell lines.

Cell lines of human T-cell acute lymphoblastic leukemias (T-ALL) have gained high interest for study of mechanisms of cytostatic drug resistance. However, they should also be suited to examine the validity and reliability of molecular cytogenetic techniques in detecting genomic alterations in neoplastic cells. Therefore, comparative genomic hybridization (CGH) and 24-color-fluorescence-in-situ-hybridization (M-FISH) were applied to eight sublines of CCRF-CEM leukemia cells selected in vitro for drug resistance and to their drug-sensitive parental counterparts. All cell lines were characterized by altered chromosome numbers and by a variety of chromosomal structural aberrations as shown by M-FISH. The great majority of anomalies detected by this technique were confirmed by CGH. Interestingly, a considerable number of the rearrangements found were imbalanced. Amplifications of 5q13 in the six methotrexate-resistant cell lines, a del(9)(p21pter) in all lines examined, and a gain of chromosome 20 in 9 of the 10 lines examined were readily detected by both techniques. The same held true for losses of chromosomes 17 and 18 in the near tetraploid cell lines which could also be confirmed by CGH. Some imbalances of genomic material detected by CGH were, however, not observed by means of M-FISH, possibly due to the limited extension of the corresponding chromosomal segment involved or the small subpopulation of cells affected. On the other hand, reciprocal translocations, balanced isochromosomes, and small deletions remained mainly undetected by CGH. A comparison of chromosomal alterations in drug-resistant and parental cell lines showed not only amplifications of chromosomal segments harboring well-known drug resistance genes, e.g., the dihydrofolate reductase gene, but also chromosomal changes which may involve novel genes associated with drug resistance. Thus, the present study has clearly unveiled the strengths and weaknesses of both techniques which can excellently complement each other. Their combination allowed a distinct improvement of the definition of the complex karyotypes of drug-resistant cell lines.

Chromosome Aberrations↗
PubMed2000

Function of the cytosolic N-terminus of sucrose transporter AtSUT2 in substrate affinity.

AtSUT2 was found to be a low-affinity sucrose transporter (K(M)=11.7 mM at pH 4). Chimeric proteins between AtSUT2 and the high-affinity StSUT1 were constructed in which the extended N-terminus and central loop of AtSUT2 were exchanged with those domains of StSUT1 and vice versa. Chimeras containing the N-terminus of AtSUT2 showed significantly lower affinity for sucrose compared to chimeras containing the N-terminus of StSUT1. The results indicate a significant function of the N-terminus but not the central cytoplasmic loop in determining substrate affinity. Expression of AtSUT2 in major veins of source leaves and in flowers is compatible with a role as a second low-affinity sucrose transporter or as a sucrose sensor.

Amino Acid Sequence↗
PubMed2000

SUT2, a putative sucrose sensor in sieve elements.

In leaves, sucrose uptake kinetics involve high- and low-affinity components. A family of low- and high-affinity sucrose transporters (SUT) was identified. SUT1 serves as a high-affinity transporter essential for phloem loading and long-distance transport in solanaceous species. SUT4 is a low-affinity transporter with an expression pattern overlapping that of SUT1. Both SUT1 and SUT4 localize to enucleate sieve elements of tomato. New sucrose transporter-like proteins, named SUT2, from tomato and Arabidopsis contain extended cytoplasmic domains, thus structurally resembling the yeast sugar sensors SNF3 and RGT2. Features common to these sensors are low codon bias, environment of the start codon, low expression, and lack of detectable transport activity. In contrast to LeSUT1, which is induced during the sink-to-source transition of leaves, SUT2 is more highly expressed in sink than in source leaves and is inducible by sucrose. LeSUT2 protein colocalizes with the low- and high-affinity sucrose transporters in sieve elements of tomato petioles, indicating that multiple SUT mRNAs or proteins travel from companion cells to enucleate sieve elements. The SUT2 gene maps on chromosome V of potato and is linked to a major quantitative trait locus for tuber starch content and yield. Thus, the putative sugar sensor identified colocalizes with two other sucrose transporters, differs from them in kinetic properties, and potentially regulates the relative activity of low- and high-affinity sucrose transport into sieve elements.

Amino Acid Sequence↗
PubMed2000

A new subfamily of sucrose transporters, SUT4, with low affinity/high capacity localized in enucleate sieve elements of plants.

A new subfamily of sucrose transporters from Arabidopsis (AtSUT4), tomato (LeSUT4), and potato (StSUT4) was isolated, demonstrating only 47% similarity to the previously characterized SUT1. SUT4 from two plant species conferred sucrose uptake activity when expressed in yeast. The K(m) for sucrose uptake by AtSUT4 of 11.6 +/- 0.6 mM was approximately 10-fold greater than for all other plant sucrose transporters characterized to date. An ortholog from potato had similar kinetic properties. Thus, SUT4 corresponds to the low-affinity/high-capacity saturable component of sucrose uptake found in leaves. In contrast to SUT1, SUT4 is expressed predominantly in minor veins in source leaves, where high-capacity sucrose transport is needed for phloem loading. In potato and tomato, SUT4 was immunolocalized specifically to enucleate sieve elements, indicating that like SUT1, macromolecular trafficking is required to transport the mRNA or the protein from companion cells through plasmodesmata into the sieve elements.

Amino Acid Sequence↗
PubMed1992

Prevalence of hepatitis C virus infections in dialysis patients and their contacts using a second generation enzymed-linked immunosorbent assay.

The prevalence of antibodies to the hepatitis C virus (HCV) was determined in 498 hemodialysis patients from three german dialysis units, 121 staff members and 42 family members using an enzyme-linked immunosorbent assay (ELISA) of the second generation which detects antibodies to a structural (C22) and to non-structural (C33c, C100, 5-1-1) recombinant antigens to HCV. Using the second generation ELISA 115 patients (23.1%) were anti-HCV positive versus 77 (15.5%) when sera were tested by an ELISA of the first generation containing only a non-structural antigen (C100). In 34 of these 40 discordant sera antibodies against at least one viral protein was found by a recombinant immunoblot assay. Of 5 sera containing antibodies to only one viral protein (C22) 3 were HCV RNA positive by polymerase chain reaction. Epidemiological evaluation of the patients revealed that the prevalence of anti-HCV was correlated to the duration of dialysis but not to the number of blood transfusions. Of 121 staff members 2 (1.6%) and 2 of 42 family members (4.7%) were positive indicating a low risk of the patients' contacts of acquiring HCV infection.

Adolescent↗
PubMed1982

Salivary secretion in reflux esophagitis.

It has been speculated that impaired salivary flow and contents contribute to abnormal acid clearance in patients with reflux esophagitis. To test this hypothesis, salivary secretion of volume, bicarbonate, and N-acetylneuraminic acid was measured in patients with reflux esophagitis, in age- and sex-matched controls, and in healthy young volunteers. Resting saliva was collected by permitting the saliva to drip into a flask every 30 s. Parotid saliva was collected by means of a Lashley capsule during stimulation by oral infusion of 1 ml/min of 2% citric acid. Total mixed saliva was collected by a dental sucker during esophageal perfusion with water and 10-mM hydrochloric acid. The volume of resting saliva and its concentration of bicarbonate were similar in the three groups. The concentration and the output of N-acetylneuraminic acid were higher in the young volunteers than in the two other groups. The volume flow and the composition of stimulated parotid saliva were similar in the three groups of subjects. Volume of total mixed saliva and concentration of bicarbonate and N-acetylneuraminic acid during esophageal perfusion with water were higher in patients with reflux esophagitis than in age- and sex-matched controls and were similar to the values found in young healthy volunteers. Acid perfusion increased the secreted volume of total mixed saliva by 150% and the concentration of bicarbonate by 30% in healthy young volunteers, but not in patients with reflux esophagitis and in the healthy age- and sex-matched controls; the concentration of N-acetylneuraminic acid was left unaffected by acid perfusion in all three groups. These findings disprove the hypothesis of impaired salivation in reflux esophagitis. The age-related loss of salivary response to acidic esophageal perfusion might be the reason why reflux esophagitis with peptic lesions affects predominantly elder people.

Adult↗