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Biomedical subjects

J Meyer

Publications and source records attributed to J Meyer.

At least 55 records · Page 3Linked to original sources
PubMed2003

Late improvement of regional wall motion after the subacute phase of myocardial infarction treated by acute PTCA in a 6-month follow-up.

BACKGROUND: The aim of this follow-up study was to investigate the late effects of acute coronary angioplasty (PTCA) on regional wall motion after the subacute phase of myocardial infarction (MI). METHODS AND RESULTS: Seventeen patients were investigated initially at a median of 11 days and again at 6 months after acute PTCA for myocardial infarction (< 8 hours after onset of symptoms) by cardiac magnetic resonance imaging. Corresponding short-axis slices encompassing the left ventricle (LV) were acquired using a standard cine MR for regional wall motion analysis and using delayed contrast enhanced magnetic resonance imaging (ceMRI) for infarct size quantification. The infarct size was similar in the subacute phase and the 6 month follow-up (20.8 and 21.9%, respectively; n.s.). Regional wall motion improved significantly in the area of hyperenhancement [percentage wall thickening (PWT) 21.9% and 37.9%, p < 0.05] in contrast to remote normal myocardium (46.4% and 38.4%; n.s.). Regional wall motion was significantly poorer in transmural compared with nontransmural MI in the subacute stage, and a late improvement could only be observed in transmural MI. CONCLUSION: Transmural areas of hyperenhancement displayed significant late long-term improvement of regional wall motion after acute PTCA, possibly related to prolonged stunning compared with nontransmural areas.

Adult↗
PubMed2003

Skin temperature recovery from cold provocation in workers exposed to vibration: a longitudinal study.

BACKGROUND: Vibration white finger (VWF) is characterised by arterial hyperresponsiveness and vasoconstriction following cold provocation. Several years after of removal from exposure, most subjects show improved finger systolic blood pressure (FSBP) under conditions of cold challenge, but continue to report cold hands and finger blanching. AIMS: To assess the underlying reasons for the persistence of cold symptoms. METHODS: A total of 204 former users of pneumatic tools with cold related hand symptoms were evaluated and then re-evaluated a year later. Symptoms were evaluated using the Stockholm Workshop Scale. Finger systolic blood pressure per cent (FSBP%) was assessed by comparing digital blood pressure in a cold provoked and normalised state. Fingertip skin temperature was measured during cooling and occlusion and during rewarming and recovery. RESULTS: There were dramatic improvements in FSBP% (14.3 mm Hg %), modest improvement in recovered skin temperature (0.86 degrees C), and no change in symptom stage. When the most symptomatic subjects (n = 75) were compared with the less symptomatic subjects (n = 129), there were similar inter-test improvements in FSBP%. Skin temperature recovery improved in the less symptomatic (+1.49 degrees C), but did not change in the most symptomatic group (-0.12 degrees C). However, the more symptomatic group had higher temperatures at the initial test, thus qualifying the result. CONCLUSIONS: Skin temperature recovery after cold challenge in subjects with VWF remains reduced in the symptomatic subjects several years after exposure removal. This is evident even when blood pressure has increased in the setting of cold provocation. Results suggest that in VWF, the dermal circulation remains impaired, even after the restoration of arterial blood pressure in the digits.

Adult↗
PubMed2003

Little anthelmintic drenching required for lambs finished over winter and spring on annually re-established irrigated pasture on the Highveld of Gauteng Province, South Africa.

As part of a trial to test the profitability of finishing weaner lambs over winter and spring on the Highveld of Gauteng province, an investigation was carried out over 4 consecutive years as to whether or not worm control was necessary while the lambs were on irrigated, improved pastures. Pastures that had not been grazed by sheep or other livestock for at least 5 years were planted to annual ryegrass (Lolium multiflora) that was ploughed under and replanted annually. Weaner lambs were randomly divided into either 2 (A and B) or 3 (A, B and C) groups and finished from April/May to November/December on a separate pasture per group. While Group A lambs were dewormed before being placed on pasture, those in Groups B and C were not. Faecal egg counts were performed at irregular intervals, and when the lambs were sold at the conclusion of each year's trial, the gastrointestinal tracts of 4-5 lambs per trial group were processed for worm recovery. Haemonchus contortus was the dominant worm species, while Trichostrongylus colubriformis, Ostertagia circumcincta and Trichuris spp. were encountered sporadically. From the results obtained it seems unlikely that there is appreciable 'carry-over' of the various worm species from year to year on pastures that are ploughed and replanted annually; thus it is improbable that there will be a build-up of anthelmintic-resistant worms. While on pasture, no drenching was required for the Group A lambs (dewormed before placing on the pasture), nor in 2 of the 4 years in Groups B or B+C that were not drenched and were lightly infected at the start. In the remaining 2 years Groups B or B+C were drenched once only during the course of each trial. Thus, under the conditions as in this study, little worm control is necessary, provided faecal worm egg counts are done to gauge the levels of infection before the lambs are placed on pasture, and to guard against the possibility of an increase in worm burdens thereafter in some years. Also, because of the apparent lack of carry-over between years, anthelmintic treatment at the time of introduction of the lambs or during the period of finishing should be safe as regards progressive selection for anthelmintic resistance. It is also likely to be cost-effective, considering the low cost of anthelmintics in relation to the price of lambs, to counter the possibility of a loss in production if lambs were to harbour relatively heavy worm burdens when introduced.

Animals↗
PubMed2002

Introgression of a quantitative trait locus for yield from Glycine soja into commercial soybean cultivars.

The value of exotic germplasm in broadening the genetic base of most crops has been demonstrated many times. However, the difficulties involved in working with exotic germplasm have limited their utility in plant breeding. Unwanted linkages often thwart the successful incorporation of beneficial exotic genes into commercial lines. Thus, the use of exotics in traditional breeding makes the process of crop improvement a tedious, time-consuming and expensive endeavor. The availability of molecular markers makes it possible to isolate specific genomic regions and transfer them into commercial varieties with minimal linkage drag. We found a yield-enhancing quantitative trait locus (QTL) from Glycine soja (Siebold and Zucc.) by evaluating a population of 265 BC(2) individuals from a cross between HS-1 and PI 407305. The yield QTL was located on linkage group B2(U26) of the soybean [Glycine max (L.) Merrill] genetic linkage map. In a 2-year, multi-location study, individuals carrying the PI 407305 haplotype at the QTL locus demonstrated a 9.4% yield advantage over individuals that did not contain the exotic haplotype. When tested in a more uniform "HS-1-like" background in two locations, we observed an 8% yield advantage for lines that carry the PI 407305 haplotype. We further assessed the QTL effect in various elite soybean genetic backgrounds. The yield effect was consistently observed in only two of six genetic backgrounds. Individuals carrying the PI 407305 haplotype at the QTL locus had a 9% yield advantage in yield trials across locations. Despite the limited adaptability of this yield-QTL across genetic backgrounds, this study demonstrates the potential of exotic germplasm for yield enhancement in soybean.

Alleles↗
PubMed2002

Effects of combined therapy of clopidogrel and aspirin in preventing thrombus formation on mechanical heart valves in an ex vivo rabbit model.

BACKGROUND: The aim of our study was to investigate the efficacy of the combination of clopidogrel and aspirin in the prevention of thrombus formation on artificial heart valves in an experimental rabbit model as compared to anticoagulation with warfarin. METHODS: Studies were performed after oral administration of clopidogrel and aspirin in group I (n=9) for 5 days, after 5+/-2 days treatment with warfarin in group II (n=9) and without medication in group III (n=9). Leaflets from Sulzer Carbomedics bileaflet valves were placed in a flow chamber. The flow chamber was filled with blood in a continuous circulation between the carotid artery and the jugular vein. RESULTS: In group III, the flow chamber was clotted after a median of 15 min of circulation. Weight analysis before and after 1 h of perfusion showed that the median thrombus weight was 9.1 mg in group I, 14.4 mg in group II and 33.7 mg in group III. Further analysis by electron microscopy showed fewer platelets and erythrocytes on leaflets in group I than on leaflet surfaces in group II. CONCLUSION: Clopidogrel and aspirin were more effective than warfarin in preventing thrombus formation on artificial heart valve leaflets in our investigation. This rabbit model with a high dosage of clopidogrel and aspirin, and a short-time exposure of the heart valve leaflets to rabbit blood under laminar flow, should be further evaluated with respect to whether it can give information about antithrombotic regimens in patients after mechanical heart valve replacement.

Animals↗
PubMed2002

[Percutaneous revascularization of multivessel coronary disease using stents - a multicenter, prospective study].

BACKGROUND AND OBJECTIVE: Symptomatic patients with multivessel coronary disease (MVD) benefit from both coronary artery bypass grafting (CABG) and percutaneous coronary angioplasty (PTCA). The >>German Angioplasty Bypass Investigation<< (GABI-I) trial randomized patients to one of these treatment strategies between 1986 and 1991. In order to evaluate the impact of current technology, in particular coronary stents, the GABI-II trial was initiated, which in 1996 and 1997 prospectively enrolled patients according to the initial GABI-I criteria. PATIENTS AND METHODS: Into the study 136 consecutive patients (108 men, 28 women; 63 +/- 12 years) were included. Patients from GABI-I served as controls. RESULTS: A mean of 2.1 +/- 0.5 vessels were treated per patient (vs. 1.9 +/- 0.5 vessels in the PTCA arm of GABI-I) and 63 % of the lesions were covered with stents. With respect to the primary endpoint less patients remained with a CCS class III or IV in GABI-II after 12 months (1,5 % vs. 8 % in the PTCA arm of GABI-I, p<0,01). No patient required emergency or urgent bypass operation in GABI-II (vs. 9 % in GABI-I, p < 0.01). After 12 months, 8 % of the patients were sent for bypass surgery (CABG) vs. 21 % in GABI-I (p < 0.001), and 20 % (vs. 23 % in GABI-I) of the patients underwent Re-PTCA. The percentage of patients without reinterventions was 72 % vs. 56 % in GABI-I (p < 0.01), but remained lower compared to patients randomized to CABG in GABI-I (94 %, p < 0.001). CONCLUSION: PTCA in patients with MVD is still associated with a higher reintervention rate as compared with CABG. However, in contrast to angioplasty a decade ago, PTCA in conjunction with stents significantly lowered the need for subsequent revascularization, which was mainly driven by the reduced necessity for bypass surgery.

Aged↗
PubMed2002

Genomewide search for type 2 diabetes mellitus susceptibility loci in Finnish families: the Botnia study.

Type 2 diabetes mellitus is a heterogeneous inherited disorder characterized by chronic hyperglycemia resulting from pancreatic beta-cell dysfunction and insulin resistance. Although the pathogenic mechanisms are not fully understood, manifestation of the disease most likely requires interaction between both environmental and genetic factors. In the search for such susceptibility genes, we have performed a genomewide scan in 58 multiplex families (comprising 440 individuals, 229 of whom were affected) from the Botnia region in Finland. Initially, linkage between chromosome 12q24 and impaired insulin secretion had been reported, by Mahtani et al., in a subsample of 26 families. In the present study, we extend the initial genomewide scan to include 32 additional families, update the affectation status, and fine map regions of interest, and we try to replicate the initial stratification analysis. In our analysis of all 58 families, we identified suggestive linkage to one region, chromosome 9p13-q21 (nonparametric linkage [NPL] score 3.9; P<.0002). Regions with nominal P values <.05 include chromosomes 2p11 (NPL score 2.0 [P<.03]), 3p24-p22 (NPL score 2.2 [P<.02]), 4q32-q33 (NPL score 2.5 [P<.01]), 12q24 (NPL score 2.1 [P<.03]), 16p12-11 (NPL score 1.7 [P<.05]), and 17p12-p11 (NPL score 1.9 [P<.03]). When chromosome 12q24 was analyzed in only the 32 additional families, a nominal P value <.04 was observed. Together with data from other published genomewide scans, these findings lend support to the hypothesis that regions on chromosome 9p13-q21 and 12q24 may harbor susceptibility genes for type 2 diabetes.

Aged↗
PubMed2002

Evolutionary conserved microsatellites in the promoter region of the 5-hydroxytryptamine receptor 2C gene (HTR2C) are not associated with bipolar disorder in females.

Two polymorphic dinucleotide repeats separated by a short spacer are localized in the promoter region of the serotonin receptor 2C gene ( HTR2C). One of the repeats was found to be evolutionary conserved between humans and rhesus monkeys. Although promoter-associated microsatellites have previously been shown to regulate expression of different genes, we did not find any significant influence of distinct HTR2C promoter microsatellite alleles on transcriptional efficiency as measured by luciferase activity and receptor availability as assayed by [(3)H]-mesulergine binding. Furthermore, no association of specific alleles with bipolar disorder was found. These results indicate that the HTR2C promoter polymorphism does not contribute significantly to the etiopathogenesis of bipolar disorder in females.

Aged↗
PubMed2002

Function of linear and cyclic RGD-containing peptides in osteoprogenitor cells adhesion process.

Cell adhesion directly influences cell growth, differentiation and migration as well as morphogenesis, integrity and repair. The extracellular matrix (ECM) elaborated by osteoblast cells constitutes a regulator of the cell adhesion process and then of the related phenomenon. These regulatory effects of ECM are mediated through integrins and some of them are able to bind RGD sequences. The aim of this study was to determine the role of the sequence and the structure of RGD-containing peptides (linear and cyclic) as well as their role in the cell adhesion process. Cell adhesion assays onto ECM proteins coated surfaces were performed using a range of linear and cyclic RGD-containing peptides. We showed a different human osteoprogenitor cell adhesion according to the coating for ECM proteins and for RGD-peptides. Inhibition assays using peptides showed different responses depending on the coated protein. Depending on the amino-acid sequence and the structure of the peptides (cyclic linear), we observed 100% inhibition of cell adhesion onto vitronectin. These results suggest the importance of sequence, structure and conformation of the peptide, which may play a crucial function in the ligand/receptor interaction and/or in the stability of the interaction.

Adult↗
PubMed2002

Predictors of tolerance to chemotherapy in older cancer patients: a prospective pilot study.

Few data are available to help predict which older cancer patient is at risk of developing chemotherapy-related toxicity. This study was a pilot for a project designing a predictive risk score. Chemotherapy patients aged 70 years and older were prospectively enrolled. Chemotherapies were adjusted for their published toxicity. 60 patients were enrolled, 59 were evaluable. Mean dose-intensity was 90.3%, range 33.3-129.0%. 47% of the patients experienced grade 4 haematological and/or grade 3-4 non-haematological toxicity. Published toxicity (MAX2), diastolic blood pressure, marrow invasion and lactate dehydrogenase (LDH) were all associated with toxicity (P<0.1); Body Mass Index, previous chemotherapy, red blood cells, platelets, polymedication with dose-intensity; and polymedication with FACT-G change. After adjustment for the published toxicity, the variables retained their significance, except for LDH and polymedication (for dose-intensity). Although the size of this pilot study imposes a cautious interpretation, patient-related and chemotherapy-related variables correlated independently with toxicity. Designing a composite predictive score to use in assessing the toxicity of multiple chemotherapy regimens therefore appears to be a valid undertaking.

Aged↗
PubMed2002

Non-invasive magnetic resonance imaging of coronary bypass grafts. comparison of the haste- and navigator techniques with conventional coronary angiography.

OBJECTIVE: The aim was the study was to evaluate the patency of coronary artery bypass grafts with the 3D Navigator and the Haste magnetic resonance imaging techniques. MATERIAL AND METHODS: Thirty-four patients with 82 grafts (18 internal mammarian artery and 64 saphenous venous grafts) were examined at 1.5 T using a phased arrray body coil. A 2D T-2 weighted turbo spin echo sequence (Haste) and a 3D-angiography sequence in navigator technique were used. Reference method was the conventional coronary angiography that was performed within 7 days. RESULTS: With the HASTE sequence 54 of 56 patent and 12 of the 16 occluded grafts were recognized, the sensitivity and specificity was 96 and 75%. The distal anastomosis could be assessed in 28 of 76 cases. With the Haste sequence 54 of the 56 patent and 12 of the 14 occluded grafts were detected correctly. Eight patent and two occluded grafts were judged as not assessable. The sensitivity and specificity was 96 and 85%. Sixty-six percent (50/76) of the distal anastomosis were identified correctly. With both sequences none of the bypass stenosis could be detected. CONCLUSIONS: The patency of coronary bypass grafts can be evaluated noninvasively with a sensitivity of 96% and a specificity of 76%. No inference can be made with respect to the nature of bypass graft stenosis. Better results can be expected with the development of a blood pool contrast medium, an improvement of the spatial resolution and in the combination of flow measurements.

Aged↗
PubMed2002

Exclusion of the neuronal nicotinic acetylcholine receptor alpha7 subunit gene as a candidate for catatonic schizophrenia in a large family supporting the chromosome 15q13-22 locus.

The gene encoding the neuronal nicotinic acetylcholine receptor alpha7 subunit (CHRNA7) is located on chromosome 15q13.2. This region was suggested to be involved in the etiopathogenesis of: (a) schizophrenia combined with a neurophysiological deficit; (b) lithium-responsive bipolar disorder; and (c) familial catatonic schizophrenia (periodic catatonia). Therefore, members of a large family with periodic catatonia strongly supporting the chromosome 15q13-22 region were genotyped with polymorphic markers localized around the CHRNA7 locus. A recombination event distally of marker D15S144 leading to the exclusion of the CHRNA7 locus from this candidate region was detected in one branch of the pedigree. This result provides strong evidence that a gene located telomeric to CHRNA7 is causative for the pathogenesis of catatonic schizophrenia in this family.

Chromosomes, Human, Pair 15↗
PubMed2002

No missense mutation of WKL1 in a subgroup of probands with schizophrenia.

Recently, a Leu309Met mutation in WKL1 (MLC1, KIAA0027), a gene mapped to chromosome 22q13.33, was reported to co-segregate with periodic catatonia, a clinical sub-type of schizophrenia, in seven members of an extended pedigree.(1) WKL1 encodes a putative membrane protein expressed exclusively in the brain, particularly in the amygdala, nucleus caudatus, thalamus, and hippocampus.(1) We screened WKL1 for etiologic mutations in 28 probands from the United States who were given a consensus diagnosis of schizophrenia and met at least one of these criteria: (1) were from multiplex schizophrenia families where at least two schizophrenic subjects were reported to display catatonic behavior at sometime during the course of their illness; or (2) were from multiplex schizophrenia families where, in a genome scan for schizophrenia susceptibility loci, evidence for excess allele sharing among affected family members for markers in the 22q13 region was seen. In addition, 15 affected subjects from 15 German pedigrees were similarly screened for causative mutations. This German cohort exhibited the catatonia phenotype but had ambiguous linkage to 22q13 and included the mutation-positive proband as a positive control. The 43 probands were screened for base changes in WKL1: 15 SNPs in the non-coding regions of the gene, three SNPs in the 3'UTR, four synonymous coding SNPs and two non-synonymous (amino acid changing) SNPs were identified. We were able to rapidly confirm the Leu309Met nucleotide change in the positive control. No missense mutations were detected in any of the other 42 probands studied. These data exclude the role of WKL1 in schizophrenia susceptibility in the subjects studied.

Adolescent↗
PubMed2002

Quantitative assessment of right ventricular volumes in severe chronic thromboembolic pulmonary hypertension using transthoracic three-dimensional echocardiography: changes due to pulmonary thromboendarterectomy.

AIMS: Evaluation of a three-dimensional reconstruction method to show the changes of right ventricular volume and systolic function when patients undergo pulmonary thromboendarterectomy for chronic thromboembolic pulmonary hypertension. METHODS AND RESULTS: In the examination of 11 patients (four female, seven male; age 56+/-10 years) before and after pulmonary thromboendarterectomy, end-diastolic and end-systolic right ventricular volumes were determined as a sum total of the calculated volumes of derived parallel slices of the right ventricle. Using a Tomtec workstation and a Vingmed CFM 800 echocardiography device, the acquired data were ECG-and respiration-triggered in the course of transthoracic examination, using step intervals of 5 degrees. The ventricular outline was traced manually on 5mm slices from longitudinal cut planes. For subsequent correction, their area measurements were displayed and the volume cross-checked against the volume from orthogonal cut planes. End-diastolic and end-systolic volumes could be quantified in 11/11 cases before surgery, but data could only be attained for 9/11 patients after surgery, because a limited apical window rendered the postoperative three-dimensional reconstruction impossible in two cases. Before surgery, right ventricular size was larger than normal and systolic function was clearly impaired in all of the patients (end-diastolic volume: 121+/-37 ml; end-systolic volume 91+/-30 ml; ejection fraction 25+/-8%). The decrease in mean pulmonary artery pressure after surgery was significant (47+/-8 vs 26+/-8 mmHg; P<0.05). End-diastolic and end-systolic right ventricular volumes had been reduced (80+/-33 ml and 54+/-31 ml respectively), and the ejection fraction had increased (36+/-9%). CONCLUSIONS: Successfully performed pulmonary thromboendarterectomy leads to a significant reduction of right ventricular chamber size and improvement of systolic function, which can be determined with great precision and quite easily, using transthoracic three-dimensional echocardiography. Published by Elsevier Science Ltd. All rights reserved.

Adult↗
PubMed2002

[Evaluation of myocardial perfusion reserve in patients with CAD using contrast-enhanced MRI: a comparison between semiquantitative and quantitative methods].

OBJECTIVE: Comparison between two semiquantitative methods and a quantitative evaluation of myocardial blood flow (MBF) for assessment of myocardial perfusion reserve (MPR) in patients with CAD. MATERIAL AND METHODS: 9 patients with coronary stenoses > 50 % were examined with an ECG-gated Saturation Recovery Turbo FLASH sequence by using Gd-DTPA as contrast agent (CA). The entive measurements were performed both during rest and hyperemia induced by adenosine. The up-slopes of the signal-time S(t) curves in the myocardium and left ventricular (LV) cavity were evaluated by a linear fit. MPR was calculated from the original up-slopes of the myocardial S(t) curves and from the up-slopes, which were normalized to the up-slopes of the LV S(t) curves, respectively. For quantification of MBF values, the mathematical model MMID 4 was used and MPR was evaluated from the MBF values. RESULTS: With all tested methods, MPR was reduced in myocardial regions subtended by arteries with stenoses >/= 70 % compared with remote regions. With MMID 4 and the normalized up-slope method, differences between severe ischemic and remote regions were statistically significant. CONCLUSION: The up-slope method with normalization and quantification with MMID 4 are more sensitive methods to differentiate between remote and ischemic myocardium than the up-slope method without normalization.

Adult↗