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Biomedical subjects

C Hilbert

Publications and source records attributed to C Hilbert.

15 recordsLinked to original sources
PubMed2002

[Early results with a monorail-stent-balloon device for endovascular treatment of renal artery stenosis].

OBJECTIVE: To evaluate the technical feasibility of a new monorail-stent-balloon device for treatment of renal artery stenosis (RAS). PATIENTS AND METHODS: During a study period of 18 months, 38 patients with proven RAS in 41 cases (hypertension n = 36, renal insufficiency n = 13) and indication for stenting (calicified ostial lesions n = 35, insufficient PTA n = 4, dissection n = 2) were enrolled into this prospective evaluation. Pre-mounted stents (Rx-Herculink(TM) 5 mm = 13, 6 mm = 34, 7 mm = 1) were implanted a transfemoral (n = 35) or transbrachial approach (n = 6). Mean grade and lengths of stenosis measured were 88 % plus minus 10 and 9 mm plus minus 5. RESULTS: Renal stent implantation was technically successful in all cases (100 %). In 7 cases a second stent had to be implanted to cover the entire lesion. The transstenotic pressure drop decreased from 88 mmHg plus minus 10 before to 1 mmHg plus minus 1.8 after the procedure. Remaining stenosis measured 0.7 % plus minus 4.2. Serum creatine levels decreased from 1.9 mm/dl to 1.5 mg/dl (n. s.), blood pressure decreased from 178/94 mmHg to 148/79 mmHg (p < 0.0001) after the intervention. Primary and secondary patency rates at 6 months were 72 % (Standard Error 9.8 %) and 77 (% (Standard Error 9.2 %), respectively. CONCLUSION: With the used monorail-stend-balloon device a technically easy, secure and exact renal stent placement is guaranteed, patency rates are similar to those described in the current literature.

Adult↗
PubMed2001

Randomized study to compare PTA alone versus PTA with Palmaz stent placement for femoropopliteal lesions.

PURPOSE: The purpose of this study was to evaluate whether percutaneous transluminal angioplasty (PTA) combined with Palmaz stent placement provides long-term advantages compared to PTA alone after 34 months of follow-up in the femoropopliteal region. MATERIALS AND METHODS: Thirty patients randomized to undergo PTA in combination with stent placement and 23 patients randomized to undergo PTA alone were evaluated. RESULTS: Mean follow-up (+/-SD) for the PTA group was 33.8 months (+/- 8.7) and for the Palmaz group 29.1 months (+/- 6.2), with a maximum follow-up period of 39 months for both groups. No significant differences in primary or secondary patency rates could be observed at 12 or 39 months. After 39 months, the primary patency rate for PTA alone was 68.4% and the secondary patency rate was 89.5%; the primary patency rate for PTA with stent placement was 62% and the secondary patency rate was 90%. CONCLUSIONS: The results of this study show that even after a long-term follow up of more than 3 years, PTA with stent placement in the femoropopliteal artery does not produce better results than PTA alone, although it does provide better initial luminal gain after the procedure.

Aged↗
PubMed2001

Interactions of HLA-B27 with the peptide loading complex as revealed by heavy chain mutations.

MHC class I heavy chains assemble in the endoplasmic reticulum with beta(2)-microglobulin and peptide to form heterotrimers. Although full assembly is required for stable class I molecules to be expressed on the cell surface, class I alleles can differ significantly in their rates of, and dependencies on, full assembly. Furthermore, these differences can account for class I allele-specific disparities in antigen presentation to T cells. Recent studies suggest that class I assembly is assisted by an elaborate complex of proteins in the endoplasmic reticulum, collectively referred to as the peptide loading complex. In this report we take a mutagenesis approach to define how HLA-B27 molecules interact with the peptide loading complex. Our results define subtle differences between how B27 mutants interact with tapasin (TPN) and calreticulin (CRT) in comparison to similar mutations in other mouse and human class I molecules. Furthermore, these disparate interactions seen among class I molecules allow us to propose a spatial model by which all class I molecules interact with TPN and CRT, two molecular chaperones implicated in facilitating the binding of high-affinity peptide ligands.

Antiporters↗
PubMed2000

[Mid-term follow-up after placement of the new balloon-expendable VIP-stent into the iliac arteries].

PURPOSE: To assess the effectiveness and mid-term patency of VIP balloon expandable stents in patients with iliac occlusive disease. MATERIAL AND METHODS: Between August and December 1997, 26 balloon-expandable VIP (Medtronic) stainless steel vascular stents were implanted in 19 patients with iliac occlusive disease. 22 lesions in common iliac (n = 11), external iliac (n = 5), common iliac plus contralateral external iliac (n = 1), and unilateral common and external iliac (n = 2) arteries were stented, allowing 20 limbs for assessment. There were 18 stenoses and 4 occlusions in 7 female and 12 male patients (mean age 65 years, range 45-80). RESULTS: All lesions were treated satisfactorily, yielding a technical success rate of 100%. Primary patency was 91% (20/22) at 6 months. In 2 lesions restenoses (90% and 70%) were observed, requiring repeated angioplasty. Color Doppler analysis at 12 months revealed no further restenoses. CONCLUSION: The new VIP balloon-expandable stents achieve very good initial technical success and good mid-term patency in the treatment of iliac occlusive disease.

Aged↗
PubMed2000

[First results after implantation of the new balloon-expanded Bridge-Stent into the iliac artery].

PURPOSE: To determine the success and patency rates of the new, balloon-expandable Bridge-stents for treatment of occlusions and stenoses of iliac arteries. MATERIAL AND METHODS: Between April and October 1999, 21 patients suffering from peripheral arterial occlusive disease were treated (22 lesions). In 20 cases high-grade stenoses and in two cases complete occlusions were treated. 23 balloon-expandable Bridge-stents were implanted in the common iliac (n = 16) and the external iliac (n = 6) artery after percutaneous transluminal angioplasty. RESULTS: All interventions were performed with technical success. The mean ankle-brachial index (ABI) increased from 0.7 +/- 0.19 before to 0.86 +/- 0.16 at 24 hours after the procedure (Rutherford +3 [n = 18] and +2 [n = 3]); the ABI measured after 6 months was 0.89 +/- 0.16. The primary cumulative patency rate amounted to 91% (20/22) at 6 months. In two cases restenosis of 75% were observed, requiring repeated angioplasty. CONCLUSION: The new balloon-expandable Bridge-stents achieve very good initial technical success and promising short-term patency in the percutaneous treatment of iliac occlusive disease.

Adult↗
PubMed2000

Mechanical thrombectomy of acute thrombosis in transjugular intrahepatic portosystemic shunts.

RATIONALE AND OBJECTIVES: To evaluate the feasibility of mechanical thrombectomy with the use of the Amplatz thrombectomy device (ATD) in restoring patency to acutely thrombosed stent-shunts after transjugular intrahepatic portosystemic shunt (TIPS) placement. METHODS: Mechanical thrombectomy with the ATD was performed in 10 consecutive patients with angiographically documented complete thrombosis of the stent-shunt (mean +/- SD, 6.6 +/- 3.4 cm), which occurred an average of 2.8 months (range, 0-11 months) after the TIPS procedure. RESULTS: In all patients, immediate restoration of patency of the stent-shunt was achieved after thrombectomy alone (n = 1), thrombectomy plus percutaneous transluminal angioplasty (PTA; n = 4), and thrombectomy, PTA, and stenting (n = 5). The mean activation time of the ATD was 253 +/- 43 seconds. The pressure gradient for portal decompression decreased from 23 +/- 6 mmHg before to 11 +/- 3 mmHg after the procedure. The primary patency rate was 80% at 3 months and 60% at 11 months. CONCLUSIONS: Mechanical thrombectomy with the ATD in acutely thrombosed TIPS is technically feasible. Mechanical thrombectomy is a potential alternative to thrombolysis.

Adult↗
PubMed1992

Potentiation of cardiodepressive action among calcium antagonists from different classes: evidence for a mechanism at the single calcium channel level.

The ability of calcium antagonists and antiarrhythmic agents to potentiate the negative inotropic effects of calcium antagonists was investigated in guinea-pig left atria. The potency of nitrendipine was enhanced by several amphiphilic agents by one order of magnitude or more (by pretreatment with quinidine or bepridil). The effect of preincubation with bepridil was investigated for a larger number of dihydropyridines. Only some of them were potentiated like nitrendipine. There was no potentiation between any two members of the same chemical group, i.e. between two dihydropyridines or two catamphiphilic calcium antagonists. The interaction between bepridil and nitrendipine was studied in more detail. In atria, its extent was influenced by several conditions, such as the stimulus frequency, the incubation temperature, or the extracellular K+ concentration. In measurements of whole-cell calcium currents in guinea-pig myocytes, the interaction was found to take place in a quantitatively similar manner. At the single channel level, an enhancement of the effects could also be demonstrated. It appears here that both drugs interact by binding to the same channel molecule. We conclude that the interaction may be due to 1.: an amphiphilic drug (like bepridil) binding to the channel very transiently and thus briefly favouring the inactivated channel state, which means that 2.: the other drug (like nitrendipine) has a higher chance to be bound because of its high affinity towards inactivated channels. Alternative explanations are also discussed.

Animals↗
PubMed1988

Presymptomatic neuropsychological impairment in Huntington's disease.

Ten asymptomatic individuals at risk for Huntington's disease (HD) were determined by the use of linked DNA probes to have a high (HD+ group) or low (HD- group) probability of having inherited the mutant gene. Neuropsychological examination, performed without knowledge of DNA results, revealed impairments in five of seven subjects in the HD+ group. Abnormalities were related to visuospatial abilities or to functions associated with the frontal lobes. All three subjects in the HD- group showed no neuropsychological impairment. Statistical analyses confirmed differences between the HD+ and HD- groups. Affected parents of subjects were at least 12 years older at symptom onset. These results demonstrate that clear neuropsychological impairment may be present in HD even when overt signs and symptoms are not expected for a number of years.

Adult↗
PubMed1988

A polymorphic DNA marker that represents a conserved expressed sequence in the region of the Huntington disease gene.

A polymorphic marker (D4S62) that is genetically closely linked to D4S10 and is in the region of the gene for Huntington disease is described. A four-allele polymorphism is detected when HincII-digested DNA is hybridized with D4S62. D4S62 maps, by Southern blot analysis using somatic-cell hybrids, to 4p16.1 closer to the centromere than does D4S10. The use of the polymorphisms detected by D4S62 increases the informativeness of markers close to the gene for Huntington disease and will be useful for preclinical diagnosis. D4S62 detects transcripts of approximately 6,000 nucleotides in rat, mouse, and monkey liver and brain. This represents the first demonstration of conserved expressed sequences close to the gene for Huntington disease.

Alleles↗
PubMed1987

First-trimester prenatal diagnosis for Huntington's disease with DNA probes.

Polymorphic DNA probes linked to the locus for Huntington disease (HD) were used for prenatal diagnosis of a 10-week fetus at 25% risk for the disease. The fetus proved to have a 48% risk of having inherited the HD mutation which was similar to that for the at-risk parent (50%). On this basis the parents elected to terminate the pregnancy. When appropriate family members are available and DNA studies are informative, prenatal diagnosis of HD with polymorphic DNA probes can determine the at-risk status of the fetus with 96% accuracy.

Adult↗