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Biomedical subjects

J Seidel

Publications and source records attributed to J Seidel.

At least 19 recordsLinked to original sources
PubMed2007

[Staging of esophageal cancer using ultrasound].

The early diagnosis of esophageal cancer is crucial for the prognosis of the disease. In contrast to cancer of the upper aerodigestive tract, the mucosa of the esophagus is not visible without the appropriate equipment. In addition to endoscopy, imaging of the esophagus is crucial for early detection of the esophageal cancer. Ultrasound of the esophagus can be performed easily and--in contrast to other imaging techniques--without side effects. Different modes of ultrasound can be performed. First, transcutaneous ultrasound allows one to detect tumors of the upper esophagus and its passage into the hypopharynx. Second, endosonography allows one to detect pathologies of the other esophageal regions including the passage into the stomach. The present review discusses the impact of both techniques against the background of the international literature.

Esophageal Neoplasms↗
PubMed2006

[Gaucher disease, Fabry disease and mucopolysaccharidosis type I--how can the rheumatologist recognise these patients?].

The lysosomal storage diseases Gaucher disease, Fabry disease and MPS I are rare inheritable metabolic disorders that are now treatable with enzyme replacement therapy. In order to avoid irreversible complications, an early diagnosis and initiation of therapy is important. Due to the musculoskeletal symptoms associated with these storage diseases, patients are likely to visit a rheumatologist, who should, therefore, be able to recognise and diagnose these rare diseases. On the basis of the causal factors behind Gaucher disease, Fabry disease und MPS I (here Scheie syndrome), key symptoms that the rheumatologist (internist or paediatrician) should be familiar with for the differential diagnosis of these patients will be discussed. In addition, a short introduction to the pathophysiology and data on the prognosis and therapy for these diseases will be presented.

Diagnosis, Differential↗
PubMed2005

Stimulated emission of surface plasmons at the interface between a silver film and an optically pumped dye solution.

Surface plasmons (SPs) are surface-bound electromagnetic waves supported by metals, offering the possibility of strong spatial confinement of electromagnetic fields on the micro- and nanoscales. They suffer, however, from strong damping caused by internal absorption and radiation losses. Here we demonstrate amplification of SPs by stimulated emission, which marks a possible solution to this problem. We use an attenuated-total-reflection setup to detect stimulated emission of SPs at the interface between a silver film and an optically pumped dye solution acting as the amplifying medium. Clear evidence of stimulated emission is provided by an excellent agreement of the experimental observations with a theoretical analysis. Amplification of SPs can be considered analogous to photon amplification in a laser, thereby suggesting novel approaches in the field of nano-optics.

Journal Article↗
PubMed2005

Traceability in fluorometry--Part I: Physical standards.

The inter-instrument, inter-laboratory, and long-term comparability of fluorescence data requires the correction of the measured emission and excitation spectra for the wavelength- and polarization-dependent spectral irradiance of the excitation channel at the sample position and the spectral responsivity of the emission channel employing procedures that guarantee traceability to the respective primary standards. In this respect the traceability chain of fluorometry is discussed from a radiometrist's point of view. This involves, in a first step, the realization of the spectral radiance scale, based on the blackbody radiator and electron storage ring, and the spectral responsivity scale, based on the cryogenic radiometer and their control via key comparisons of the national metrology institutes. In a second step, the characterization including state-of-the art uncertainties of the respective source and detector transfer standards such as tungsten strip lamps, integrating sphere radiators, and trap detectors used to disseminate these radiometric quantities to users of spectroscopic techniques is presented.

Journal Article↗
PubMed2004

[Engineering and characterization of functional osteochondral replacement tissue].

Extensive osteochondral lesions require repair of the cartilage and underlying bone. We generated osteochondral repair tissue by tissue engineering. Standardized defects, 7 x 5 x 5 mm, were created in femoropatellar grooves of adult rabbits. Engineered cartilage, generated in vitro starting from chondrocytes and a biodegradable scaffold, was implanted using Collagraft as subchondral support. Cell-free implants, defects left empty, and unoperated knee joints served as controls. Explants were characterized morphologically and mechanically. Engineered cartilage implants were superior to cell-free implants and to natural healing of empty defects with respect to the histologic score and Young's modulus of the 6-month repair tissue. These data suggest that engineered cartilage can provide primary stability for the treatment of critical osteochondral defects.

Bone Remodeling↗
PubMed2004

Occult, life-threatening, cardial tumor in syndactylism in Gorlin Goltz syndrome.

Pediatric, orthopedic, plastic, and hand surgeons perform the surgical correction of syndactylism. It is sometimes forgotten, however, that syndactylism can be part of a syndrome. The components of such a syndrome can each be life threatening. A 7-month-old boy was hospitalized for correction of cutaneous syndactylism. The mother claimed that, with the exception of the syndactylism, her son was healthy. However, review of the admission documents found that the family physician suspected Gorlin Goltz syndrome. A preoperative echocardiography showed 3.9-cm intramural tumor in the wall of the left ventricle. Electrocardiography documented ventricular tachycardia. Because of the danger of life-threatening malignant ventricular tachycardia, the tumor was resected. Before the resection, cardiac transplantation was considered because of the size of the tumor. Histologic examination found a fibroma. When observing syndactylism, one must always be aware of the possibility of a syndromic disease. It is particularly important that screening investigations, including electrocardiography and echocardiography, are performed before surgical treatment.

Basal Cell Nevus Syndrome↗
PubMed2004

Experiment assessment of mass effects in the rat: implications for small animal PET imaging.

In vivo imaging using positron emission tomography (PET) is important in the development of new radiopharmaceuticals in rodent animal models for use as biochemical probes, diagnostic agents, or in drug development. We have shown mathematically that, if small animal imaging studies in rodents are to have the same "quality" as human PET studies, the same number of coincidence events must be detected from a typical rodent imaging "voxel" as from the human imaging voxel. To achieve this using the same specific activity preparation, we show that roughly the same total amount of radiopharmaceutical must be given to a rodent as to a human subject. At high specific activities, the mass associated with human doses, when administered to a rodent, may not decrease the uptake of radioactivity at non saturable sites or sites where an enzyme has a high capacity for a substrate. However, in the case of binding sites of low density such as receptors, the increased mass injected could saturate the receptor and lead to physiologic effects and non-linear kinetics. Because of the importance of the mass injected for small animal PET imaging, we experimentally compared high and low mass preparations using ex vivo biodistribution and phosphorimaging of three compounds: 2-fluoro-2-deoxyglucose (FDG), 6-fluoro-L-metatyrosine (FMT) and one receptor-directed compound, the serotonin 5HT1A receptor ligand, trans-4-fluoro-N-[2-[4-(2-methoxylphenyl) piperazino]ethyl]-N-(2-pyridyl) cyclohexane- carboxamide (FCWAY). Changes in the mass injected per rat did not affect the distribution of FDG, FMT, and FCWAY in the range of 0.6-1.9 nmol per rat. Changes in the target to nontarget ratio were observed for injected masses of FCWAY in the range of approximately 5-50 nmol per rat. If the specific activity of such compounds and/or the sensitivity of small animal scanners are not increased relative to human studies, small animal PET imaging will not correctly portray the "true" tracer distribution. These difficulties will only be exacerbated in animals smaller than the rat, e.g., mice.

Algorithms↗
PubMed2004

Intracellular expression of pro-inflammatory cytokines (IL-1alpha, TNF-alpha, and IL-6) in chronic hepatitis C.

The study aimed at localizing TNF-alpha, IL-1alpha, IL-6 at light and electron microscope levels in patients with chronic hepatitis C, using the immunocytochemical techniques in biopsy material from patients with chronic hepatitis C and at comparing the expression of the cytokines with histopathological changes. Our studies demonstrated an augmented expression of all cytokines in liver biopsies in chronic hepatitis C, in comparison with respective values, obtained in control biopsy material. The highest expression of the cytokines was observed in hepatocytes. That was confirmed by electron microscopy, which demonstrated the cytokines mainly in altered ER cisterns and in the cytoplasm. In children, the expression of IL-1alpha was negatively correlated with staging, while in adult patients; the staging was positively correlated with the expression of TNF-alpha. The new element involves demonstration of cellular and subcellular expression of TNF-alpha, IL-1alpha and IL-6 in hepatocytes in in vivo infection.

Adult↗
PubMed2003

Recurrent vomiting and ethylmalonic aciduria associated with rare mutations of the short-chain acyl-CoA dehydrogenase gene.

We report identification of short-chain acyl-CoA dehydrogenase (SCAD) deficiency in a 12-year-old boy who suffered from recurrent attacks of vomiting once or twice a year from infancy. Growth and development were normal and there were no muscular symptoms. Metabolic screening was performed during a hospitalization at 8 years of age and revealed an increased excretion of ethylmalonic acid (EMA; 45-80 mmol/mol creatinine, normal 0.2-6.6), suggesting a degradation defect of short-chain fatty acids. An increased n-butyrylcarnitine was found in freshly collected serum (0.9 micromol/L; normal <0.4) but not in dry blood spots. Neither of the frequent SCAD gene variants 625G>A and 511C>T was present, but direct sequencing of the promoter and coding regions of the SCAD gene revealed that the patient had mutations on both alleles: 417G>C (Trpl15Cys) and 1095G>T (Gln341His). Neither mutation has been described before in compound heterozygosity or homozygosity. Enzymatic investigations subsequently confirmed a defect of SCAD in both fibroblasts and muscle extracts. Furthermore, expression studies of both mutations demonstrated impaired enzyme function or structure. To our knowledge, this case is the first description of a patient with proven SCAD deficiency presenting with recurrent emesis but without other symptoms, and emphasizes the wide clinical phenotype of this disorder.

Alleles↗
PubMed2003

Evidence for a new microdeletion syndrome in 15q21.

We report on the fourth known case with an interstitial deletion in 15q21. In the present case the breakpoints have been determined by GTG-banding, microdissection and the recently developed multicolor banding (MCB) technique as 15q21.1-q21.3. Common features in all four cases are mental retardation, growth retardation, a beak-like nose with hypoplastic alae nasi and a thin upper lip. Additional frequent features are small hands and feet, hypotonia, low hair implantation, low set ears, clinodactyly and obesity. The possibility that a critical region for a new microdeletion-syndrome is situated in 15q21 is discussed.

Abnormalities, Multiple↗
PubMed2002

A molecular oyster: a neutral anion receptor containing two cyclopeptide subunits with a remarkable sulfate affinity in aqueous solution.

An artificial anion receptor is presented, in which two cyclohexapeptide subunits containing l-proline and 6-aminopicolinic acid subunits in an alternating sequence are connected via an adipinic acid spacer. This compound was devised to stabilize the 2:1 sandwich-type anion complexes that are observed when the two cyclopeptide moieties are not covalently connected and to obtain a 1:1 stoichiometry for these aggregates. Electrospray ionization mass spectrometry and NMR spectroscopic investigations showed that the bridged bis(cyclopeptide) does indeed form defined 1:1 complexes with halides, sulfate, and nitrate. ROESY NMR spectroscopy and molecular modeling allowed a structural assignment of the sulfate complex in solution. The stabilities of various anion complexes were determined by means of NMR titrations and isothermal titration microcalorimetry in 50% water/methanol. Both methods gave essentially the same quantitative results, namely stability constants that varied in the range 105-102 M-1 and decreased in the order SO42- > I- > Br- > Cl- > NO3-. This order was rationalized in terms of the size of the anions with the larger anions forming the more stable complexes because they better fit into the cavity of the host. The ability of sulfate to form stronger hydrogen bonds to the NH groups of the receptor, in addition to its slightly larger ionic radius with respect to iodide, causes the higher stability of the sulfate complex. No significant effect of the countercation on complex stability was observed. Furthermore, complex stability is enthalpically as well as entropically favored. A comparison of the iodide and sulfate complex stabilities of the ditopic receptor with those of a cyclopeptide that forms 1:1 anion complexes in solution showed that the presence of a second binding site increases complex stability by a factor of 100-350.

Anions↗
PubMed2002

Monitoring the correction of glycogen storage disease type 1a in a mouse model using [(18)F]FDG and a dedicated animal scanner.

Monitoring gene therapy of glycogen storage disease type 1a in a mouse model was achieved using [(18)F]FDG and a dedicated animal scanner. The G6Pase knockout (KO) mice were compared to the same mice after infusion with a recombinant adenovirus containing the murine G6Pase gene (Ad-mG6Pase). Serial images of the same mouse before and after therapy were obtained and compared with wild-type (WT) mice of the same strain to determine the uptake and retention of [(18)F]FDG in the liver. Image data were acquired from heart, blood pool and liver for twenty minutes after injection of [(18)F]FDG. The retention of [(18)F]FDG was lower for the WT mice compared to the KO mice. The mice treated with adenovirus-mediated gene therapy had retention similar to that found in age-matched WT mice. These studies show that FDG can be used to monitor the G6Pase concentration in liver of WT mice as compared to G6Pase KO mice. In these mice, gene therapy returned the liver function to that found in age matched WT controls as measured by the FDG kinetics in the liver compared to that found in age matched wild type controls.

Animals↗
PubMed2002

Growth factors for sequential cellular de- and re-differentiation in tissue engineering.

A model system for the in vitro generation of cartilaginous constructs was used to study a tissue engineering paradigm whereby sequentially applied growth factors promoted chondrocytes to first de-differentiate into a proliferative state and then re-differentiate and undergo chondrogenesis. Early cultivation in medium with supplemental TGF-beta1/FGF-2 doubled cell fractions in 2-week constructs compared to unsupplemented controls. Subsequent culture with supplemental IGF-I yielded large 4-week constructs with high fractions of cartilaginous extracellular matrix (ECM) and high compressive moduli, whereas prolonged culture with supplemental FGF-2 yielded small 4-week constructs with low ECM fractions and moduli. Sequential supplementation with TGF-beta1/FGF-2 and then IGF-I yielded 4-week constructs with type-specific mRNA expression and protein levels that were high for type II and negligible for type I collagen, in contrast to other growth factor regimens studied. The data demonstrate that structural, functional, and molecular properties of engineered cartilage can be modulated by sequential application of growth factors.

Animals↗
PubMed2002

Electronic determination of root canal length in primary teeth with and without root resorption.

AIM: To test an electrical device for determining root canal length in primary teeth in vitro, and to compare it with the radiographic length measurement. METHODOLOGY: Two examiners determined the root canal length of 24 extracted maxillary primary incisors (12 with visible root resorption and 12 without) using an electrical root canal meter (Tri Auto ZX, Morita, Dietzenbach, Germany). The instrument was left in the root canal after the second examination and a radiograph was taken. The whole tooth was cleared by immersion in methylsalicylate and subsequently photographed. Both radiographs and photographs of cleared teeth were measured and compared with the electronic measurements. RESULTS: The evaluation of the radiographs showed a mean distance between the instrument tips and apices of 0.60 (+/- 0.41) mm; evaluation of the cleared teeth showed an equivalent distance of 0.62 (+/- 0.40) mm. The mean distance between instrument tip and acceptable working length (determined with the clearing method) was 0.26 (+/- 0.24) mm in teeth without resorption and 0.29 (+/- 0.30) mm in teeth with resorption. CONCLUSION: The presence of resorption in primary teeth did not affect the accuracy of electrical measurement of root canal length in vitro. The application of this method in primary teeth should be evaluated further.

Confidence Intervals↗
PubMed2002

PTHrP and cytokeratins in human epidermis.

We have demonstrated the presence of parathyroid hormone-related peptide (PTHrP) in cells of human epidermis, employing immunocytochemical techniques. Cells of human epidermal layers demonstrated variable intensity of the reaction. The least pronounced reaction was detected in cells of the basal and the most pronounced reaction in cells of the granular layer. Ultrastructural studies demonstrated that gold particles labeled bundles of keratin filaments. Therefore, at the subsequent stage of the studies we examined the type of filaments to which PTHrP was bound, using immunocytochemical reactions with antibodies against cytokeratins 10, 14, 16 and 19. Positive reaction was obtained for cytokeratins 10, 14 and 16. The reaction pattern obtained for cytokeratins 10 and 16 most closely resembled that of PTHrP. Double labeling with colloidal gold was performed at the ultrastructural level. The results obtained in this way demonstrated that PTHrP most probably binds to filaments built of cytokeratin 16. By binding to the cytokeratin, PTHrP may possibly affect growth and differentiation of keratinocytes.

Epidermal Cells↗
PubMed2002

Expression of mRNA for cytokines (TNF-alpha and IL-1alpha) in human cytomegalovirus (HCMV) and hepatitis B virus (HBV) infections.

The study was aimed at detecting cellular sources of transcripts for two cytokines, TNF-alpha and IL-1alpha in infection with human cytomegalovirus (HCMV) or hepatitis B virus (HBV). The studies were performed on paraffin sections of organs (liver, pancreas, spleen, lungs) obtained upon autopsy from a child deceased due to acute inborn HCMV infection, on paraffin sections of liver biopsy, obtained from a child with HCMV-induced chronic hepatitis, and of liver biopsies obtained from children with chronic type B hepatitis (n = 13). The classical in situ hybridization was applied with digoxygenin-labeled probes and amplification by the ImmunoMax technique. In HCMV infection, the most pronounced expression of mRNA for TNF-alpha and Il-1alpha was detected in pancreatic islets (mainly in beta cells) and, then, in a decreasing sequence, in liver (in macrophages and sinusoidal endothelial cells) and in lungs (in alveolar macrophages). No expression of the two cytokines was detected in the spleen. In HBV infection, weak expression of TNF-alpha and more intense expression of IL-1alpha in the liver were observed, mainly in sinusoidal endothelial cells and in macrophages as well as in hepatocytes. These results were confirmed by immunocytochemical experiments.

Child↗
PubMed2001

Molecular analysis and long-term follow-up of patients with different forms of 6-pyruvoyl-tetrahydropterin synthase deficiency.

UNLABELLED: The outcome of 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency, the most common form of tetrahydrobiopterin (BH4) deficiency, depends on factors such as severity of the disease, type of mutation, time of diagnosis, and mode of treatment. We investigated five patients from four different families, four of them presenting with the severe form of PTPS deficiency and one with the mild peripheral form. In this study, missense (L26F, T67M, P87L, V124L, D136G, D136V) and nonsense (R15-16ins) mutations were detected by reverse transcriptase polymerase chain reaction and sequence analysis. Two patients with the severe form were compound heterozygotes (T67M/P87L and D136G/R15-16ins), two siblings were homozygous for the D136V mutation, and in the patient with the mild form, heterozygous L26F/V124L mutations were present. Two patients are on combined therapy with L-dopa/carbidopa/5-hydroxytryptophan plus BH4, the siblings are on monotherapy with BH4, and the patient with the mild form is now off treatment, presenting with normal plasma phenylalanine levels. CONCLUSION: Long-term follow-up shows that the outcome of 6-pyruvoyl-tetrahydropterin synthase deficiency benefits from treatment started in the first months of life and that the phenotype may change with age. Additionally, depending on the type of mutations, prenatal damage to the fetus may multiply the clinical abnormalities and thus worsen the prognosis of the disease. In patients initially diagnosed with the mild peripheral form of the disease, therapy with tetrahydrobiopterin should be stopped after some time to test whether hyperphenylalaninaemia was only a transient condition.

Adolescent↗