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Biomedical subjects

A Vogel

Publications and source records attributed to A Vogel.

At least 37 records · Page 2Linked to original sources
PubMed2001

Clinical comparison of two intraocular pressure measurement methods: SmartLens dynamic observing tonography versus Goldmann.

PURPOSE: To compare intraocular pressure measurements obtained with SmartLens, a gonioscopic contact lens, to those from Goldmann applanation tonometry. METHODS: Eighty volunteers (20 healthy individuals and 60 glaucoma patients from the university eye hospital's outpatient department) were examined using conventional Goldmann tonometry and the new SmartLens tool. For each device three replicate measurements were performed. A paired t-test and the corresponding mean difference confidence interval approach were used to assess deviations in location of the two tonometric methods; the test procedure of Maloney and Rastogi was used for comparison of precision in paired data. Intraindividual differences were evaluated according to the approach of Altman and Bland. RESULTS: There was a mean difference of 5.6 mmHg (95% CI: 4.3 mmHg; 6.8 mmHg; P<0.01) in intraocular pressure between the two methods with a significant overestimation by SmartLens tonometry compared to Goldmann tonometry (P<0.01). The 95%-limits of agreement ranged from -5.4 mmHg to +16.6 mmHg for individual patients. The measurement method variance of SmartLens was higher (Maloney-Rastogi test; P <0.01). The mean coefficients of variation for intraindividual replicates were 10.1% (SmartLens) and 3.8% (Goldmann; P <0.01). CONCLUSIONS: Accepting Goldmann tonometry as gold standard for intraocular pressure measurement, the SmartLens method shows considerable variation and therefore is not proven to be an adequate substitute for Goldmann tonometry.

Adult↗
PubMed2001

Reproducibility of optical biometry using partial coherence interferometry : intraobserver and interobserver reliability.

PURPOSE: To evaluate the intraobserver and interobserver variability in axial length (AL), anterior chamber depth (ACD), and corneal radius measurements using an optical biometry instrument based on partial coherence interferometry (PCI). SETTING: Johannes Gutenberg University, Mainz, Germany. METHODS: In this observational case series and interobserver reliability trial, 30 healthy, emmetropic to moderately myopic eyes of 15 volunteers were evaluated. The AL, ACD, and corneal radius were measured 20 times in 10 eyes by 1 observer to evaluate the intraobserver variability. To evaluate the interobserver variability, the measurements were taken in 20 eyes by 5 different observers. Measurements were performed using the IOLMaster (Carl Zeiss) based on PCI. The data description is based on coefficients of variation and the statistical inference on reliability estimation based on analysis of variance. The main outcome measures were intraobserver and interobserver variability and reliability in AL, ACD, and corneal radii. RESULTS: The intraobserver variability (SD) was +/-25.6 microm for AL, +/-33.4 microm for ACD, and +/-12.9 microm for corneal radius. The coefficients of variation were 0.1%, 0.9%, and 0.17%, respectively. The interobserver variability (SD) was +/-21.5 microm for AL, +/-29.8 microm for ACD, and +/-15.9 microm for corneal radius. The coefficients of variation were 0.09%, 0.82%, and 0.21%, respectively. The reliability was 99.9% for AL, 97.8% for ACD, and 99.8%/99.5% for corneal radius (r1/r2). The slightly reduced reliability in ACD measurement was caused by a reduced intraobserver reliability of 1 of the 5 observers (R = 0.87). CONCLUSION: Partial coherence biometry using the IOLMaster for AL measurement was highly reliable, offering observer-independent measurement results.

Adult↗
PubMed2001

Genetic link of hepatocellular carcinoma with polymorphisms of the UDP-glucuronosyltransferase UGT1A7 gene.

BACKGROUND & AIMS: Hepatocellular carcinoma is associated with risk factors including hepatitis C, hepatitis B, cirrhosis, genetic liver diseases, and environmental carcinogens. Uridine 5'-diphosphate-glucuronosyltransferases are a superfamily of detoxifying enzymes capable of tobacco-borne carcinogen detoxification and cellular protection. This study examines the association of UGT1A7 and UGT1A9 gene polymorphisms with hepatocellular carcinoma. METHODS: Genomic DNA from the blood of 59 patients with hepatocellular carcinoma and 70 control subjects without evidence of cancer was analyzed by UGT1A7- and UGT1A9-specific PCR, sequencing analysis, and temperature gradient gel electrophoresis. RESULTS: Three UGT1A7 missense mutations were detected defining the UGT1A7*2, UGT1A7*3, and UGT1A7*4 alleles. Wild-type UGT1A7 alleles were present in 41.4% of controls but only in 6.8% of cancer patients (P < 0.001; odds ratio [OR], 9.73; 95% confidence interval [CI], 3.17-29.83). UGT1A7 polymorphisms were present in 93.2% of hepatocellular cancer patients, 74.5% carried the UGT1A7*3 allele (P < 0.001; OR, 10.76; 95% CI, 4.75-24.38), which combines the W208R, N129K, and R131K mutations and encodes a protein with low carcinogen detoxification activity. No UGT1A9 polymorphisms were detected. CONCLUSIONS: The significant association of hepatocellular carcinoma with the UGT1A7*3 allele encoding a low detoxification activity protein is identified and implicates UGT1A7 as a risk gene of hepatocarcinogenesis in addition to a role as potential marker for cancer risk assessment in chronic liver disease.

Adolescent↗
PubMed2001

Autoimmune regulator AIRE: evidence for genetic differences between autoimmune hepatitis and hepatitis as part of the autoimmune polyglandular syndrome type 1.

The mechanisms driving the immune-mediated destruction of hepatic tissues in autoimmune hepatitis (AIH) are unknown. Recently the autoimmune regulator (AIRE), a gene associated with the development of the autoimmune polyglandular syndrome type 1 (APS-1), was cloned. About 15% to 20% of APS-1 patients develop hepatitis. However, the role of AIRE mutations in AIH, primary sclerosing cholangitis (PSC), and primary biliary cirrhosis (PBC) is not known. To address this issue patients with AIH (n = 94), PSC (n = 60), and PBC (n = 30) were analyzed for the presence of mutations in exons 6, 8, and 10 of AIRE by single stranded conformation polymorphism and sequence analysis. Autoantibody patterns of patients with defects in AIRE were analyzed by indirect immunofluorescence, enzyme-linked immunosorbent assay and Western blot. Heterozygous mutations of AIRE were identified in 3 patients: a patient with PBC and a patient with AIH type 1 carried a R257X mutation, and a patient with AIH type 2, diabetes mellitus type 1 (IDDM), thyroid disease, and atrophic gastritis carried a G305S mutation in the first PHD ring finger domain of the AIRE protein. None of the 3 patients with a defective AIRE allele showed autoantibodies, which are known to associate with APS-1. These findings show a differential genetic association of autoimmune liver diseases and hepatitis in APS-1. The subgroup of patients with heterozygous mutations in AIRE does not represent patients with an incomplete APS-1 syndrome. However, the Aire gene defect showed that genes involved in the induction of immunologic tolerance provide candidates for etiologic factors in autoimmune liver diseases.

Adolescent↗
PubMed2001

Autoimmune hepatitis associated with coagulation disorders and immunethyreopathy.

We present the case of a 42-year-old female patient with the diagnoses of autoimmune hepatitis type I and autoimmune thyroiditis. Furthermore this patient had an unusual combination of coagulation disorders with homozygous Factor V Leiden mutation (APC resistance) and presence of antiphospholipid antibodies, leading to deep vein thromboses and miscarriages. Only few cases with the combination of autoimmune hepatitis and antiphospholipid antibodies have been described and almost all of them had become symptomatic with the antiphospholipid syndrome. As both autoimmune phenomenons furthermore share similar HLA-patterns, their coincidence is probably not as uncommon as the limited number of case reports suggests. Therefore attention in patients with autoimmune hepatitis should be focused on thrombophilia.

Activated Protein C Resistance↗
PubMed2001

Factors related to self-efficacy for use of condoms and birth control among women at risk for HIV infection.

Many women who are at risk for HIV do not regularly use condoms, particularly with their main partners. In this paper we examine factors related to self-efficacy for condom use with main and other partners and self-efficacy for birth control in 2864 women interviewed in five urban high-risk communities. Limited social and economic resources, dependence on a main partner, and risk factors, including exchanging sex for money or drugs and binge drinking, were found to be negatively related to self-efficacy. Segmentation analysis identified groups of women with low self-efficacy who should be the focus of preventive interventions.

Adolescent↗
PubMed2001

Rapid DNA typing of HLA-B27 allele by real-time PCR using lightcycler technology.

For clinical diagnostic routine we developed a fast DNA typing of HLA-B27 by PCR and real-time detection using LightCycler technology. The method combines the sensitivity and specificity of PCR with the swiftness of the LightCycler system. The amplification step was performed with a primer set coding for a region in the third exon common to B*2701 to B*2705. The PCR cycles were monitored continuously using the SYBR Green I dye. Beta-globin was used as an internal control. An analysis of 32 samples with one PCR run was completed within 40 minutes. After amplification a melting curve analysis permitted the accurate identification of the PCR amplicons. The mean melting temperatures (Tm) were 90.5 degrees C and 87.3 degrees C, which are characteristic for HLA-B27 and beta-globin, respectively. A comparison of 300 samples which were typed for HLA-B27 with a conventional sequence-specific polymerase chain reaction (SSP-PCR) and with the new method demonstrated a perfect correlation (specificity 100%). In summary, the method described is fast, reliable, cost-effective and well adapted for routine laboratory testing.

Alleles↗
PubMed2001

Ex-vivo hemoperfusion (eHPS) of pig-lungs with whole human blood: effects of complement inhibition with a soluble C1-esterase-inhibitor.

OBJECTIVES: Xenotransplantation could be a future alternative to allotransplantation due to increasing organ shortage. Complement activation plays a major role in hyperacute rejection (HAR) in pig-to-human combinations. We developed an ex-vivo hemoperfusion (EHP) system to investigate pathophysiology of HAR in the lung. After standardizing the model, the effect of a soluble complement inhibitor (C1-INH, Berinert) was investigated. METHODS: Pig lungs were harvested following cold perfusion with Celsior preservation solution. EHP was performed using fresh heparinized human blood plus C1-INH (n = 6) or heparinized human blood as control (n = 4). Bloodgas analyses (BGA), pulmonalarterial pressure (PAP) were monitored. P-selectin and L-selectin were measured. Tissue samples were taken and microscopic changes evaluated. RESULTS: BGA, PAP, macroscopic and microscopic changes in the control group showed HAR, while the C1-INH group showed significantly longer function. Leucocytes and platelets were markedly activated in the control, whereas in the treated group L-selectin and P-selectin values indicated lower activation. HE stainings showed maintained lung architecture after perfusion of pig-lungs with human blood plus C1-INH. Immunohistochemistry showed less C1q, C3, C5b-9 activation in the C1-INH group. CONCLUSIONS: Investigation of interaction of human blood with pig lung endothelium could be done in this model. C1-INH attenuates HAR in a pig-to-human lung transplantation model by decreasing the activation of adhesion molecules. C1-INH could play a role in induction therapy of future lung xenotransplantation.

Animals↗
PubMed2000

Healon5 versus Viscoat during cataract surgery: intraocular pressure, laser flare and corneal changes.

BACKGROUND: The use of a viscoelastic substance facilitates cataract surgery. Healon 5 is a new viscoelastic product with special rheological properties. We evaluated the postoperative effect of Viscoat and Healon5 on intraocular pressure (IOP), central corneal thickness (CCT), endothelial cell counts and laser flare. METHODS: Forty-eight eyes of 48 patients undergoing routine phacoemulsification followed by foldable IOL implantation were enrolled. Either Healon5 or Viscoat was used according to a block-randomization scheme. The aspiration technique was standardized. IOP, CCT, endothelial cell counts and laser flare were compared pre- and postoperatively. Statistical analysis was performed using the two-sample Wilcoxon test. Data description was based on median and quartiles, while graphic description was performed by non-parametric box plots. RESULTS: Viscoat demonstrated a statistically significant higher IOP than Healon5 at 4 and 8 h postoperatively (P< 0.01 and < 0.05, respectively). Further, the laser flare values were statistically significantly higher for the Viscoat than for the Healon5 group 8 h postoperatively (P<0.05). Endothelial cell loss did not differ significantly between the two groups (relative change in endothelial cell density after 3 months: -4.3% for the Healon5 group and -6.2% for Viscoat group). CONCLUSION: There was neither a statistically nor a clinically significant difference in endothelial cell loss after the use of Healon5 or Viscoat in routine cataract surgery. However, the IOP in the early postoperative period was higher in the Viscoat group than in the Healon5 group.

Adult↗
PubMed2000

Intra-oral storage phosphor and conventional radiography in the assessment of alveolar bone structures.

OBJECTIVES: To compare storage phosphor (SP) with conventional film radiography for accuracy of linear measurements of the marginal alveolar bone and visibility of anatomical structures. METHODS: Linear measurements were made in paired SP and conventional images of dried human mandibles with a metal pin fixed 10 mm below the alveolar crest. One observer measured the distance from the alveolar crest to the reference point on the radiographs. The difference between the measured and the true distance was calculated. Two observers rated the visibility of bony structures (periodontal ligament space, periapical bone tissue, alveolar crest) in 51 paired digital and conventional images of 21 patients on a 3-point scale. Overall agreement and Kappa index were calculated. RESULTS: Accuracy of linear measurements was higher in digital radiography (mean difference 0.17 mm) than in conventional radiography (mean difference 0.59 mm). Overall, the two observers rated visibility higher in conventional radiographs. The Kappa indices for the periodontal ligament space and periapical bone indicated fair to almost perfect agreement (kappa = 0.38 and 0.5; kappa = 0.39 and 0.84) while for the alveolar crest there was only poor or moderate agreement (kappa = 0.2 and 0.5). CONCLUSIONS: The small differences in linear measurements indicate that the Digora system is suitable for clinical assessment of periodontal and peri-implant bone loss. The visibility of dental structures depends as much on the individual features assessed, as the radiographic system.

Alveolar Process↗
PubMed2000

New bivalent thrombin inhibitors with N(alpha)(methyl)arginine at the P1-position.

A series of bivalent thrombin inhibitors was synthesized, consisting of a d-phenylalanyl-prolyl-N(alpha)(methyl)arginyl active site blocking segment, a fibrinogen recognition exosite inhibitor part, and a peptidic linker connecting these fragments. The methylation of the P1 amino acid led to a moderate decrease in affinity compared with the unmethylated analog. In addition, it prevented the thrombin catalyzed proteolysis, independent of the P1' amino acid used. This is a significant advantage compared to the original hirulogs, which strictly require a proline as P1' amino acid to reduce the cleavage C-terminal to the arginyl residue. Several analogs were prepared by incorporation of different P1' amino acids found in natural thrombin substrates. The most potent inhibitor was I-11 [dCha-Pro-N(Me)Arg-Thr-(Gly)5-DYEPIPEEA-Cha-dGlu] with a Ki of 37 pM. I-11 is highly selective and no inhibition of the related serine proteases trypsin, factor Xa and plasmin was observed. The stability of I-11 in human plasma in vitro was strongly improved compared to hirulog-1. In addition, a significantly reduced plasma clearance of I-11 was observed after intravenous injection in rats. Results from molecular modeling suggest that a strong reorganization of the hydrogen bonds in the active site of thrombin may result in the proteolytic stability found in this inhibitor series.

Amino Acid Sequence↗
PubMed1999

Investigations on acoustic on-line monitoring of IR laser ablation of burned skin.

BACKGROUND AND OBJECTIVE: In burn surgery necrotic tissue has to be removed prior to grafting. Tangential excision causes high blood loss and destruction of viable tissue. Pulsed infrared laser ablation can overcome both problems because of its high precision and the superficial coagulation of the remaining tissue. We investigated the ablation noise to realize an acoustic feedback system for a selective removal of necrotic tissue. MATERIALS AND METHODS: We studied free-running Er:YAG laser ablation of gelatin and burned skin. Schlieren laser flash photography was used to investigate the ablation dynamics generating the ablation noise. Acoustic signals were detected by a condenser microphone and a piezoelectric airborne transducer. Tissue discrimination was based on the evaluation of the normalized acoustic energy. RESULTS: The ablation noise is mainly generated by shock wave emission and fast vaporization during the first part of the laser pulse. Frequency components of the ablation noise above 200 kHz are only detectable with the piezoelectric transducer. The normalized acoustic energy differs significantly between gelatin samples of different water content and between necrotic and vital tissue. CONCLUSIONS: Large bandwidth transducers are essential for an acoustic on-line monitoring of free-running Er:YAG laser ablation of burned skin. The normalized acoustic energy is a suitable parameter for the discrimination between necrotic and vital tissue.

Acoustics↗
PubMed1999

Development of an automated microbial sensor system.

An automated whole cell biosensor system was developed by integration of immobilized microbial cells in a flow-through system with screen-printed flow-through electrodes as detectors. The detectors used were thick-film Pt-electrodes in a 3-electrode configuration constructed as sandwich flow-through cells with a volume of about 36 microliters polarized at -900 mV. The measuring principle was the determination of oxygen consumption due to the microbial metabolism. Fructose was used as model analyte. The microorganisms were immobilized on cellulose-acetate membranes and integrated into a newly created reaction chamber (membrane reactor). The microbial cells used were Rhodococcus erythropolis and Issatchenkia orientalis known to be suitable for the determination of biological oxygen demand.

Biosensing Techniques↗
PubMed1999

Mastitis in the first year postpartum.

BACKGROUND: Limited information is available about the frequency and risk factors for lactation mastitis. The purpose of this study was to investigate frequency, risk factors, and outcome for lactation mastitis. METHODS: We analyzed data from a cohort study of 350 mothers with healthy term infants, who were followed up for one year postpartum. RESULTS: Eighty-three women (23.7% of the sample) reported one or more episodes of mastitis symptoms, and 61 (17.4%) women reported symptoms including fever. Fifty-six women (16%) received one or more courses of antibiotics for mastitis. Thirty women (8.5%) of the total cohort had recurrent episodes of mastitis symptoms. A total of 123 episodes of mastitis symptoms were reported. No cases of abscess were reported. Using multiple logistic regression, the adjusted risk ratio for mastitis symptoms associated with sore nipples in the first month was 2.07 (95% CI = 1.17, 3.66). A reduced risk of mastitis was associated with maternal smoking during pregnancy, with supplementation with water in the first month, and with the use of a pacifier on a daily basis within the first month. A history of mastitis symptoms was associated with a longer overall duration of breastfeeding. CONCLUSIONS: Our results suggest that mastitis may be a marker for an ample milk supply. Mothers presenting with mastitis can be reassured that the outlook for continued successful lactation is good. Further research is needed to investigate the reasons for recurrence of mastitis and the etiology of episodes occurring late in lactation.

Adult↗
PubMed1999

Factors associated with the duration of breastfeeding.

A cohort study of healthy term infants was conducted to identify factors associated with breastfeeding duration. Three hundred and fifty mothers delivering in one obstetric hospital in Auckland, New Zealand were recruited. Ninety-five percent were followed up until 1 y. Breastfeeding was initiated by 97.4%, the median duration of breastfeeding was 7.6 mo, and 30% were continuing some breastfeeding at 12 mo. Adjusted risk ratios for shorter duration of breastfeeding were: maternal age <25 y, 2.33 (95% confidence interval = 1.33, 4.05); maternal age 25-34, 1.45 (1.01, 2.09) compared to maternal age > or =35; planning to cease breastfeeding < or =6 mo, 2.39 (1.65, 3.46); planning to breastfeed for as long as possible, 1.48 (1.00, 2.18), or not knowing plans 2.13 (1.36, 3.32) when compared to planning to cease breastfeeding after 6 mo; inverted nipples, 2.02 (1.26, 3.23), daily dummy use 1.62 (1.20, 2.18) or use of formula in the first month 2.79 (2.05, 3.80). Reporting mastitis, 0.67 (0.48, 0.94), and sharing the mother's bedroom at 3 mo, 0.69 (0.51, 0.92) were associated with a reduced risk for shorter duration of breastfeeding. We recommend that during the antenatal period attention be directed at mothers' plans for duration of breastfeeding, that mothers be encouraged to have their baby in their bedroom, and that the use of formula and dummies should be discouraged in the first months of life.

Adult↗