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Biomedical subjects

M Weber

Publications and source records attributed to M Weber.

At least 37 records · Page 2Linked to original sources
PubMed2006

[Deep lamellar keratoplasty versus penetrating keratoplasty for keratoconus].

OBJECTIVE: To determine the advantages, safety, and accuracy of deep anterior lamellar keratoplasty (DLK) versus penetrating keratoplasty (PK) in terms of visual acuity, astigmatism, and endothelial preservation in corneal diseases with healthy endothelium. Of these candidates for keratoplasty, the study investigated keratoconus patients with no other ophthalmic abnormalities. MATERIALS AND METHODS: This comparative nonrandomized retrospective study investigated 22 patients with keratoconus requiring surgery, who underwent keratoplasty in the Nantes University Hospital between 1 June 2002 and 1 January 2004. Ten DLK, ten PK and two PK converted DLK cases were analyzed. Follow-up at 2 weeks and at 3, 6, 9, and 18 months is reported for visual acuity, astigmatism, pachymetry, specular microscopy, and intraocular pressure (IOP). Data are compared before and after surgery at each follow-up date. RESULTS: Preoperative visual acuity improved in both groups from 0.14+/-0.13 to 0.8+/-0.17 postoperatively. There was no significant difference between the two groups before and at each time after surgery for visual acuity and astigmatism (3.5+/-2 diopters in the PK group and 3+/-0.9 D in the DLK group). There was a statistical difference for IOP with two occurrences of increased IOP up to 30 mmHg in the PK group. Endothelial cell count analysis showed an immediate postoperative decrease of 10% in the DLK group (versus approximately 40% in the PK group), remaining rather stable the 1st year (-3.3%), although cell loss in the PK group declined up to 10% more at 18 months. DISCUSSION: With no statistical difference between the two groups for visual acuity and astigmatism, DLK is effective. It is safer than PK in terms of IOP disturbance (leading cause of graft failure) and endothelial cell loss. DLK converted into PK (16%) showed the same profile as first-intention PK. CONCLUSION: Despite very similar effectiveness, DLK in keratoconus surgery should be proposed rather than PK because it appears safer not only in the short term but also probably in the long term, with no risk of endothelial cell rejection.

Adult↗
PubMed2006

Urinary excretion of an intravenous 26Mg dose as an indicator of marginal magnesium deficiency in adults.

BACKGROUND: Measurement of magnesium (Mg) status is problematic because tissue Mg deficiency can be present without low serum Mg concentrations. OBJECTIVE: To evaluate a modified version of the Mg retention test using stable isotopes for the assessment of Mg status in general, and the detection of marginal Mg deficiency in particular. DESIGN: A modified version of the Mg retention test using a small dose of (26)Mg was evaluated for assessment of Mg status in 22 healthy subjects. Muscle Mg concentration was used as reference for Mg status. A muscle biopsy was taken from the lateral portion of the quadriceps muscle from each subject. After 2 to 4 weeks, 11 mg of (26)Mg (as MgCl(2) in 14 ml water) were injected i.v. over a period of 10 min and all urine was collected for the following 24 h. Excretion of the isotopic label was expressed as percentage of the administered dose excreted in urine within 24 h. RESULTS: Mean +/- s.d. Mg concentration in muscle was 3.85 +/- 0.17 mmol/100 g fat-free dried solids. Mean +/- s.d. excretion of the injected dose within 24 h was 7.9 +/- 2.1%. No correlation was found between muscle Mg concentration and excretion of the isotopic label (r (2 ) = 0.061, P = 0.27). CONCLUSIONS: In this study, urinary excretion of an intravenous Mg tracer was not influenced by muscle Mg concentration and its usefulness for the detection of marginal Mg deficiency could therefore not be demonstrated. SPONSORSHIP: Swiss Foundation for Nutrition Research and Swiss Federal Institute of Technology, Zurich, Switzerland.

Adult↗
PubMed2006

Endothelial mechanotransduction, nitric oxide and vascular inflammation.

Numerous aspects of vascular homeostasis are modulated by nitric oxide and reactive oxygen species (ROS). The production of these is dramatically influenced by mechanical forces imposed on the endothelium and vascular smooth muscle. In this review, we will discuss the effects of mechanical forces on the expression of the endothelial cell nitric oxide synthase, production of ROS and modulation of endothelial cell glutathione. We will also review data that exercise training in vivo has a similar effect as laminar shear on endothelial function and discuss the clinical relevance of these basic findings.

Animals↗
PubMed2006

The diallelic locus encoding the minor histocompatibility antigen HA-1 is evolutionarily conserved.

The polymorphic minor histocompatibility antigen HA-1 induces powerful T-cell alloreactivities with important consequences for graft-vs-tumor activity and development of graft-vs-host disease in patients after human leukocyte antigen-matched stem-cell transplantation (SCT). In view of possible translational animal studies, we analyzed the evolutionary conservation of the diallelic HA-1 locus in four mammalian species. Our results show that rodents do not encode the HA-1(H) allele, neither show polymorphism in this position on the HA-1 gene. Contrariwise, the HA-1(H) allele is present in non-human primate species and dogs. Interestingly, both the HA-1(H) T-cell epitope and its non-immunogenic counterpart HA-1(R) are present in the latter species. Thus, the HA-1 allelic polymorphism is conserved in evolution in primates and dogs.

Alleles↗
PubMed2006

The 3' portion of the mouse H19 Imprinting-Control Region is required for proper tissue-specific expression of the Igf2 gene.

Genomic imprinting at the H19/Igf2 locus is governed by a cis-acting Imprinting-Control Region (ICR), located 2 kb upstream of the H19 gene. This region possesses an insulator function which is activated on the unmethylated maternal allele through the binding of the CTCF factor. It has been previously reported that paternal transmission of the H19(SilK) deletion, which removes the 3' portion of H19 ICR, leads to the loss of H19 imprinting. Here we show that, in the liver, this reactivation of the paternal H19 gene is concomitant to a dramatic decrease in Igf2 mRNA levels. This deletion alters higher-order chromatin architecture, Igf2 promoter usage and tissue-specific expression. Therefore, when methylated, the 3' portion of the H19 ICR is a bi-functional regulatory element involved not only in H19 imprinting but also in 'formatting' the higher-order chromatin structure for proper tissue-specific expression of both H19 and Igf2 genes.

Animals↗
PubMed2006

Nickel release, a possible indicator for the duration of antiplatelet treatment, from a nickel cardiac device in vivo: a study in patients with atrial septal defects implanted with an Amplatzer occluder.

UNLABELLED: The present study was undertaken to evaluate the safety and release of nickel after implantation of a nickel device (Amplatzer occluder) in patients with an atrial septal defect (ASD) receiving antiplatelet therapy. METHODS: Blood and urine samples were obtained from 24 patients with ASD before occluder implantation (baseline) and during a 12-month post closure period. Antiplatelet drugs were administered for the initial 6-month period post implantation. The nickel content in the specimens was determined using electrothermal atomic absorption spectroscopy. The clinical, sonographic and magnetic resonance imaging follow-ups were carried out 1 week, 1 month, 6 months and 12 months post implantation. RESULTS: Mean baseline concentrations of nickel in serum and urine were within normal range with values of 0.6 +/- 0.2 microg/l and 3.1 +/- 1.2 microg/l, respectively. During the 6-week post closure period, the time needed for the formation of neointima on the surface of the graft, nickel levels in serum increased up to 5-fold (p < 0.01 versus baseline). Mean concentrations in serum and urine returned to baseline levels within 4-6 months post implantation. All patients showed satisfactory clinical improvements and there was no sonographic evidence of complications. CONCLUSIONS: The initial dissolution of nickel from the Amplatzer occluder is not a specific cardiovascular risk and is temporarily linked to the formation of the non-thrombogenic neointima on the surface of the graft. The antiplatelet drug regimen used (300 mg aspirin + 75 mg clopidogrel daily for 3 months in the initial phase and 100 mg aspirin daily for a further 3 months) appears to cover the period of neointima formation on the nickel device when nickel levels are significantly elevated. However, further studies in a larger number of patients and over a period greater than 12 months are needed to confirm the validity of these conclusions and to formulate definitive recommendations on the duration of the antiplatelet treatment.

Adult↗
PubMed2005

Left ventricular adaptation after atrial septal defect closure assessed by increased concentrations of N-terminal pro-brain natriuretic peptide and cardiac magnetic resonance imaging in adult patients.

OBJECTIVE: To determine in an observational study whether N-terminal pro-brain natriuretic peptide (NT-proBNP) is raised in patients with an atrial septal defect (ASD) and whether concentrations change after interventional closure. METHODS: 12 patients (6 men, mean (SD) age 44.4 (18.6) years) with a moderate sized ASD type II (23.3 (4.5) mm, pulmonary to systemic flow ratio 2.1 (0.68)) were investigated. In all patients a magnetic resonance imaging (MRI) study was performed and NT-proBNP was assessed at baseline and early (9 (13) days) and late (138 (64) days) after intervention. RESULTS: Concentrations of NT-proBNP were found to be within the normal range at baseline (median 87 pg/ml, interquartile range 65-181 pg/ml) but increased early after the interventional closure (315 pg/ml, 133-384 pg/ml, p = 0.005 versus baseline). The increase of NT-proBNP was associated with an increase in left ventricular dimensions as assessed by MRI (left ventricular end diastolic volume 104 (27) ml to 118 (27) ml, p = 0.003). Late after ASD closure NT-proBNP returned to baseline concentrations (102 pg/ml, 82-188 pg/ml, p = 0.004 versus early follow up). CONCLUSION: These findings suggest the presence of transitory haemodynamic stress during adaptation of the left ventricle after ASD closure, which may contribute to the understanding of the pathological mechanism of acute heart failure and delayed improvement of exercise capacity after ASD closure.

Adult↗
PubMed2005

[BENEFIT Kidney--significance of a nephrology screening at intervention outset and therapy success].

BACKGROUND AND OBJECTIVE: Early specialist care of patients with renal disease, including timely and planned onset of dialysis, determine the course of the disease, quality of life, hospitalization and life expectancy. A multi-centre enquiry by standardized questionnaire was undertaken to define and analyse medical care of newly dialysis-requiring patients. PATIENTS AND METHODS: Data on 551 patients in five different regions of Germany who for the first time required renal replacement treatment were prospectively collected between July 2002 and March 2003. Documentation of history, clinical findings and biochemical tests was done on consecutive patients with a standardized questionnaire, until the desired number of cases was reached. RESULTS: The mean age of the patients (55.4% males) was 64.8 years. 30.7% had diabetes mellitus, 22.3% arterial hypertension/nephrosclerosis and 16.9% glomerulonephritis/vasculitis. Early predominantly nephrological care had been undertaken in 38.7% of patients. 59.0% were cared for almost exclusively by their general practitioner until the time when dialysis was started. 229 patients (41.6%) were referred to specialist (nephrologists) only when dialysis had become necessary. The onset of dialysis was at the right time in only 50.5% of this group. Comparing the care given by nephrologists with that by general practitioners, elective (i.e. planned) dialysis was begun in 81.0% vs. 48.0% (p<0.05). Hospitalization in the two groups was 54.5% vs. 83.7% (p<0.05), the duration of hospital stay 11.4 vs. 17.4 days (p<0.05). CONCLUSION: Fewer than 40% of patients with chronic renal disease in preterminal renal failure (stage IV) were under the care of nephrologists. The lower the degree of nephrological care the more frequent was there a delay in the onset of dialysis treatment. The incidence and the duration of hospital stay was longer. Structured treatment pathways and incentives need to be formulated to reduce the incidence of wrong or substandard treatment of patients with impaired renal function.

Aged↗
PubMed2005

[A rare case of birenal malacoplakia with renal failure].

HISTORY AND ADMISSION FINDINGS: A 45 year old man was admitted to our hospital because of fever, loss of appetite, and deterioration of general health. For two weeks the patient suffered from diarrhea which had resulted in moderate volume depletion. In addition, he complained of bilateral flank pain at the time of admission. Furthermore, the patient had a history of heavily drinking alcohol as well as cigarette smoking for many years. He had never attended a medical doctor before. INVESTIGATIONS: The patient presented with the clinical picture of acute renal failure and urosepticaemia which was caused by Escherichia coli. The kidneys were found to be at the upper limit of normal by sonography. Magnetic resonance imaging revealed signal-alterations in both kidneys with hyper- and hypointense zones in the renal parenchyma. DIAGNOSIS: To clarify the cause of rapid deterioration of renal function, we performed a renal biopsy. The histology of the renal specimen revealed an unusual type acute bacterial interstitial nephritis most likely due to an infection with E. coli. The clinical picture, the laboratory findings and renal histology, lead to the diagnosis of birenal malakoplakia. TREATMENT AND COURSE: After intravenous and subsequent oral antibiotic therapy the fever and the clinical signs of urosepticaemia subsided and renal function gradually improved. Antibiotic therapy and supplementation with vitamins were continued for 20 weeks. Five years after initial diagnosis, renal function was stable at a glomerular filtration rate of approximately 45 ml/min. CONCLUSIONS: Malakoplakia of the kidney is a rare form of bacterial interstitial nephritis and requires long-term antibiotic therapy.

Acute Kidney Injury↗
PubMed2005

Evaluation of the correlation between time corpses spent in in-ground graves and findings at exhumation.

To determine how long pathological findings persist after burial and which factors play a role in decomposition of a corpse, we evaluated all bodies exhumed under the auspices of the Institute of Legal Medicine at the Hannover Medical School between 1978 and 1997. A total of 87 exhumations (54 men, 33 women) were performed in this period. The time bodies remained buried varied between 5 days and 16.8 years (mean 1.5 years, median 2.3 months). Fifty-six percent of the bodies were exhumed after at most 3 months, 10% remained buried for greater than 3 years. Pathomorphological changes of the soft tissues and the internal organs remained evident after several months, in some cases after several years of burial. Overall, it was possible to evaluate internal organs after 5 years of burial. Bodies became mostly decomposed after approximately 8 years at the earliest, although it was still possible to evaluate some soft tissue remnants after 16.8 years. In stepwise logistic regression, both the length of time the body was buried (p < 0.00005) and the time of year (p < 0.0019) clearly affected the rate of physical change. The variables of sex (p = 0.33), age (p = 0.61) and changes in the integrity of the body before burial (trauma, autopsy before burial; p = 0.15) did not influence the physical state of the body after exhumation. Our data show that much information may be gained from an exhumation even after significant time has passed since burial.

Adolescent↗
PubMed2005

[Pre-operative measurement of heart rate variability in diabetics: a method to estimate blood pressure stability during anaesthesia induction].

BACKGROUND: In diabetics severe hyopotension can occur during anaesthesia as a consequence of cardiovascular autonomic neuropathy (CAN). A simple approach to recognize CAN is heart rate variability (HRV) measured at rest. The aim of this study was to determine the relationship between pre-operatively measured HRV and blood pressure stability during induction phase of anaesthesia. PATIENTS AND METHODS: A total of 35 diabetics undergoing an ophthalmosurgical procedure under general anaesthesia were investigated. HRV was examined one day before surgery by the following parameters: coefficient of variation (CV), root mean squared successive difference (RMSSD), and power spectrum. Anaesthesia was induced with thiopental and fentanyl and maintained with enflurane/N(2)O; tracheal intubation was performed after relaxation with vecuronium. Patients who developed a drop in systolic blood pressure below 90 mmHg during anaesthesia induction were assigned to group H (hypotensive), the other patients to group N (normotensive). The groups were compared regarding HRV and other variables. RESULTS: Of all patients 13 developed hypotension during anaesthesia induction (group H). The groups were comparable regarding the demographic data. Parameters of HRV, with the exception of spectral power in low frequency (LF) band of power spectrum, were significantly lower in group H. The groups differed mainly in relation to spectral power in the mid-frequency (MF) band of the power spectrum, and especially regarding CV. In patients with normal CV incidence of hypotension after anaesthesia induction was 11%, but in patients with abnormally reduced CV, 65% (p=0.002). CONCLUSION: The results confirm a significant relationship between HRV pre-operatively measured at rest and blood pressure stability during anaesthesia induction in diabetics. Particularly examination of CV, a simple test feasible within few minutes, may be useful in pre-operative risk stratification of these patients. Application of the time consuming traditional test combination to identify CAN seems to be unnecessary.

Aged↗
PubMed2005

[Evidential basis in bariatric surgery].

Bariatric surgery is currently considered the best treatment option for morbid obesity. With the rapid development of laparoscopic techniques, a significant increase in the number bariatric procedures in recent years can be observed. Various surgical techniques to treat morbid obesity have been described, but only few prospective studies compare the different procedures, leading to a lack of evidence for their use. However, from the available literature some general recommendations can be given: (a) preoperative workup in an interdisciplinary team is mandatory, (b) primary bariatric procedures should be performed laparoscopically, and (c) the combination of restrictive and malabsorptive techniques is more efficient than a purely restrictive method, which is also true for the treatment of comorbid diabetes and arterial hypertension. In this paper, we present recent developments in bariatric surgery, with special emphasis on the available evidence for the best treatment of morbidly obese patients.

Bariatric Surgery↗
PubMed2005

[Early diagnosis of chronic kidney diseases].

Chronic kidney diseases frequently progress to end-stage renal failure over a period of several years. Ultimately, the glomerular filtration apparatus and tubulus are destroyed to such an extent that renal replacement therapy is required. This process may last longer than 10 years. To avoid loss of renal function, chronic kidney diseases should be diagnosed as early as possible so that therapeutic measures are initiated in time. Medications which prevent or delay progression to end-stage renal failure, e.g. ACE inhibitors and AT(1) blockers, are more effective if started early in the course of renal disease. A significant number of patients with chronic kidney disease are still diagnosed too late and are without adequate therapy so that chances for prevention and/or delay of chronic kidney disease are missed.

Chronic Disease↗
PubMed2005

[Early diagnosis of chronic systemic inflammatory disorders].

Functionally relevant damage caused by chronic systemic inflammatory disorders of autoimmune and/or unknown origin can be reduced or sometimes avoided by early initiation of treatment. This requires a correct diagnosis which makes treatment as early as possible. Due to the often uncharacteristic symptoms at the onset of disease, early diagnosis in systemic inflammatory disorders represents a diagnostic challenge. This review outlines current standards and limitations in the early diagnosis of rheumatoid arthritis, collagen vascular diseases and primary systemic vasculitides. Recent advances especially in serology and imaging techniques have improved early diagnosis of systemic inflammatory disorders.

Arthritis, Rheumatoid↗
PubMed2005

Incications and complications of invasive diagnostic procedures and percutaneous coronary interventions in the year 2003. Results of the quality control registry of the Arbeitsgemeinschaft Leitende Kardiologische Krankenhausarzte (ALKK).

BACKGROUND: The ALKK registry contains about 20% of the invasive and interventional cardiological procedures performed in Germany. METHODS: In 2003 a total of 82,282 consecutive diagnostic invasive and 30,689 interventional procedures from 75 hospitals were centrally collected and analyzed. RESULTS: The main indication for an invasive diagnostic procedure was coronary artery disease in 92.5% of cases, myocardial disease in 1.6%, impaired left ventricular function in 4.0%, valve disease in 4% and other indications in 1.9%. An acute coronary syndrome was present in 25% of the patients. The rate of severe complications in patients with a lone diagnostic invasive procedure was low (<0.5%). The indication for percutaneous coronary intervention (n=30,689) was stable angina in 44.1%, ST elevation myocardial infarction in 22.3%, non ST elevation myocardial infarction in 14.8%, unstable angina in 10.0%, silent ischemia in 2.2%, prognostic in 5.2% of patients. The majority of interventions were performed directly after the diagnostic procedure (n=23,887=78.6%). The intervention was successful in 94.6% of cases. Stent implantation was performed in 77.2%, with 1 stent in 88.4%, two stents in 7.6% and 3 or more stents in 3.3%. A drug-eluting stent was implanted in 3.6% of the cases. The complication rate after PCI was influenced by the indication for the intervention. The in-hospital mortality in patients with cardiogenic shock was 33%, while in patients with stable angina, silent ischemia and prognostic indication only 0.2% died. CONCLUSION: There is an increase of invasive diagnostic and interventional procedures in patients with acute coronary syndromes, with 47% of PCIs performed in these patient. PCIs were performed in 75% of the cases directly after the diagnostic procedure. The rate of stent implantation seems to have reached a plateau at around 80%, while drug-eluting stents were implanted only in a minority of cases. The complication rate is mainly dependent on the clinical presentation of the patients and the indication for PCI.

Aged↗
PubMed2005

Treatment of in-stent restenosis with sirolimus-eluting-stents -- a six month clinical and angiographic follow-up.

Treatment of in-stent restenosis (ISR) remains a therapeutic challenge since many pharmacological and mechanical approaches have shown disappointing results except for brachytherapy. Drug-eluting stents (DES) have been reported to effectively reduce ISR in de novo lesions. We studied 55 consecutive patients with ISR in native coronary arteries and 7 with ISR in saphenous vein grafts (SVG) with elective indication for percutaneous coronary intervention (PCI), who underwent successful implantation with DES. No in-hospital postprocedural major adverse cardiac events were observed. All but one patient (n=61) underwent an angiographic follow-up at 183+/-30 days. Grade of stenosis was assessed by quantitative coronary angiography (QCA) at index procedure and at control angiography. Restenosis (>50%) occurred in 5 patients (8.2%). Target vessel revascularization was performed in an additional 4 patients. Minimal intimal hyperplasia was observed in all segments covered by DES (late loss 0.08+/-0.37 mm, loss index 0.11+/-0.47). One patient suffered from subacute stent thrombosis due to discontinuation of clopidogrel medication. At six month follow-up two patients had died. Death was not related to a restenosis in the treated segment. Conclusion Our experiences with DES treatment of ISR lesions show good angiographic and clinical results at index procedure and at the 6 month follow-up with low sub acute thrombosis rate as compared with existing treatment modalities. Restenosis rate seems to be at least as low as reported for brachytherapy.

Blood Vessel Prosthesis↗
PubMed2005

[Pain assessment in invasive diagnostic procedures. Comparison of an eleven-point numerical rating scale and a six-point verbal rating scale for pain measurement in bone marrow puncture].

BACKGROUND AND OBJECTIVE: Pain measurement during diagnostic procedures is an accepted prerequisite for appropriate therapy. In this study, the agreement between rankings of pain intensity on a numerical and a verbal rating scale was analyzed. METHODS: Patients attending a haematological outpatient clinic who underwent bone marrow puncture were requested to assess pain intensity perceived during the procedure on a elen-point numerical and a six-point verbal rating scale. RESULTS: Analysis of patients' pain ratings in 263 bone marrow punctures showed a very good correlation between numerical and verbal rating scale (Spearman correlation coefficient 0,86). By means of a transfer instruction categories of the verbal rating scale were assigned to figures of the numerical rating scale (0 - no pain, 1 or 2 - mild p., 3, 4 or 5 moderate p., 6 or 7 severe p., 8, 9 or 10 - very severe and worst possible pain). The resulting transfer table showed a good agreement with a weighted kappa of 0.72 (95% confidence interval: 0.66-0.79). CONCLUSION: Both scales can be employed efficiently for pain assessment during diagnostic procedures. Verbal categories can be assigned to numerical values and vice versa numerical values to verbal categories. However, in view of the inter-individual variations it appears appropriate to re-assure pain perception with each patient in order to avoid over- or undertreatment.

Biopsy↗