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S Simon

Publications and source records attributed to S Simon.

At least 19 recordsLinked to original sources
PubMed2006

[Fulminant course of a Takayasu's arteritis and rare mesenteric arterial maninfestion].

Takayasu's arteritis is a systemic disease, presenting as chronic inflammation of the main arteries. It usually affects the aorta and its large branches. General symptoms often include fatigue, subfebrile temperatures and weight loss. Complaints due to perfusion disorders are, for example, muscle pain, dizziness or claudication. Takayasu's arteritis is a rare disease which generally occurs in female patients under 40 years of age. We report on a patient with primary involvement of the mesenteric arteries. The disease process was fulminant and refractory to all therapeutic strategies. According to our knowledge this is the first case report from Germany of Takayasu's arteritis with mesenteric infarction.

Angiography↗
PubMed2006

Study of yttrium containing bioactive glasses behaviour in simulated body fluid.

The influence of yttrium oxide on the bioactivity of glasses in the system SiO(2)-Na(2)O-P(2)O(5)-CaO-B(2)O(3)-K(2)O-MgO was studied in a simulated body fluid (SBF). Two series of glasses with different bioactivity were investigated. The reaction layers formed on the surface of the exposed glasses were evaluated by means of back scattered electron imaging of scanning electron microscopy equipped with energy dispersive X-ray analysis (BEI-SEM/EDXA). The concentration of Y, Ca and P released from the glasses into SBF, during 21 days was determined using inductively coupled plasma-emission spectroscopy ICP-AES and inductively coupled plasma-mass spectroscopy ICP-MS. Introducing yttrium in the selected bioactive glass tended to diminish the bioactivity of the glasses. The thickness of the calcium phosphate layer decreased with increasing yttrium oxide content. The same effect was also observed when yttrium oxide partially replaced only calcium, magnesium and phosphorous oxide in the precursor glass. The data show that we can produce bioactive glasses with yttrium oxide as a component. By suitable tailoring of the rest of the glasses the yttrium effect on the glass behavior in SBF should be possible to control and thus produce yttrium containing glasses with desired bioactivity.

Biocompatible Materials↗
PubMed2005

Titanium--hydroxyapatite porous structures for endosseous applications.

Materials for uncemented endosseous implants have to assure an as short as possible osseointegration time. Thus, a material with both surface bioactivity and a porous outer structure can become a preferred choice for this type of applications. This paper presents a class of titanium-base PM composites, reinforced with particulate hydroxyapatite. Raw materials were titanium powder, obtained through hydriding--milling--dehydriding, with the grain size of 63-100 microm, and sol-gel hydroxyapatite (HA) powder, produced by the reaction between Ca(NO3)2 x 4H2O and (NH4)2HPO4. Blends with 5 to 50% HA were prepared and pressed in a rigid die, producing single composition or gradual composition samples. The applied pressure was of 400, 500 or 600 MPa. Sintering was performed in vacuum, at 1160 ( composite function)C. All samples, although well sintered, displayed swelling during sintering, due to diffusion into the matrix. The increase in volume is more severe for higher amounts of HA in the green compacts and for higher applied compaction pressure. Compacts with a gradual increase of the HA content are recommended from the functional and mechanical point of view, but the increase should be slow, not to produce interlayer cracks. The outer surface shows interconnected pores, suitable for the ingrowth of vital new bone.

Bone and Bones↗
PubMed2005

Random urine calcium/osmolality in the assessment of calciuria in children with decreased muscle mass.

BACKGROUND: Random urine Ca/creatinine (UCa/Cr) is used to estimate 24-hour Ca excretion. However, due to decreased urine creatinine excretion in children with decreased muscle mass (DMM), UCa/Cr overestimates their Ca excretion. OBJECTIVE: To evaluate whether in children with DMM random urine Ca/osmolality (UCa/Osm) can accurately predict hypercalciuria (24-hour urine Ca > 4.0 mg/kg) and at which "cutoff" value. METHODS: 19 children with DMM and 29 with normal muscle mass (NMM), ages 6 - 17 years, were studied. DMM was diagnosed based on clinical findings and decreased serum creatinine, and confirmed by low urine creatinine excretion. Over 24 hours, subjects collected each void separately. After each sample was analyzed, samples of each participant were combined to form a 24-hour specimen from which an aliquot (AL) was obtained; 24-hour urine Ca was first correlated with the corresponding AL Ca/Cr and Ca/Osm. As an internal control, a similar assessment ofproteinuria was conducted. In the next step, AL data were compared with individual urine samples to identify the time of day when a random sample best correlates with AL. RESULTS: The correlation coefficient between 24-hour Ca and AL Ca/Cr in all children was 0.61, in NMM 0.96, and in DMM 0.69 (in all p < 0.001). The correlation coefficient between 24-hour urine Ca and AL Ca/Osm in all children was 0.90, in NMM 0.90, and in DMM 0.91 (in all p < 0.001). In children with DMM, the correlation coefficient of 24-hour protein with AL protein/Cr was 0.75, and with protein/Osm 0.98 (both p < 0.001). Receiver operating characteristic curves showed UCa/Cr as a better predictor of 24-hour Ca > 4.0 mg/kg in NMM, whereas UCa/Osm was a better predictor of hypercalciuria in DMM patients. In NMM, UCa/Cr ratio > 0.20 had sensitivity of 88% and specificity of 96% in detecting 24-hour Ca > 4.0 mg/kg, whereas in those with DMM UCa/Osm (x 10) ratio of > 0.25 had sensitivity of 100% and specificity of 93% in detecting hypercalciuria. It was further found that random urine specimens collected between 9:00 a.m. and 2:00 p.m. best represented 24-hour urine data. CONCLUSION: In children with DMM, UCa/Osm can successfully replace UCa/Cr as a screening tool for hypercalciuria.

Adolescent↗
PubMed2004

PrPSc accumulation in myocytes from sheep incubating natural scrapie.

Because variant Creutzfeldt-Jakob disease (vCJD) in humans probably results from consumption of products contaminated with tissue from animals with bovine spongiform encephalopathy, whether infectious prion protein is present in ruminant muscles is a crucial question. Here we show that experimentally and naturally scrapie-affected sheep accumulate the prion protein PrP(Sc) in a myocyte subset. In naturally infected sheep, PrP(Sc) is detectable in muscle several months before clinical disease onset. The relative amounts of PrP(Sc) suggest a 5,000-fold lower infectivity for muscle as compared to brain.

Animals↗
PubMed2004

Abnormal prion protein in genetically resistant sheep from a scrapie-infected flock.

The central molecular event in transmissible spongiform encephalopathies, such as scrapie in sheep, is the accumulation in tissues of an abnormal isoform of the cellular prion protein. A previous investigation of 26 sheep showed that the accumulation of PrP(res) in brain correlated more with the prnp genotype than with the severity of the clinical disease. Here, the ability of a sandwich ELISA to detect PrP(res) distribution in the brain was demonstrated. Immunohistochemistry also strongly supported the hypothesis that the dorsal motor nucleus of the vagus nerve is the possible entry site in the brain for the scrapie agent. Remarkably, three asymptomatic (or possibly asymptomatic for scrapie) sheep carrying an allele known to be associated with clinical scrapie resistance (ARR), which were negative for the detection of PrP(res) by Western blotting and immunohistochemistry, were positive for the presence of PrP(res) by ELISA, raising the possibility of carriers resistant to the disease and possibly contributing to the persistence of scrapie in certain flocks.

Alleles↗
PubMed2004

Prevalence of chronic renal failure in the diabetic population at the University Hospital of the West Indies.

The prevalence of chronic renal failure (CRF) in 460 patients with diabetes mellitus attending the diabetic outpatient clinic at the University Hospital of the West Indies in Jamaica was determined from a review of medical records. The prevalence of CRF was 10% (39/386) in the diabetic clinic population. Significant positive associations with CRF were found with male gender (20/98, 20% vs 19/287, 7%; odds ratio (OR), 3.24; p = 0.001); age 60 years and older (22/162; 14% vs 17/221, 8%; OR, 2.01; p = 0.04); fasting blood glucose concentrations exceeding 8.0 mmol/L (22/162, 13% vs 12/182, 7%; OR, 2.08; p = 0.05); the presence of significant proteinuria as a marker for outcome (13/39, 33% vs 48/346, 14%; OR, 3.60; p = 0.02) and peripheral vascular disease (6/20, 30% vs 139/386, 10%; OR, 4.75; p = 0.005). The prevalence of CRF did not differ significantly between patients with Type 1 and Type 2 diabetes mellitus. Also, the presence of CRF was not significantly associated with duration of diabetes mellitus, type of hypoglycaemic agents used, or history of hypertension. However, the presence of persistent proteinuria was significantly associated with duration of diabetes mellitus exceeding five years (46/255, 17% vs 11/149, 7%; OR, 2.52; p = 0.005) and a history of hypertension (41/235, 17% vs 20/198, 10%; OR, 1.88; p = 0.03) but not with age or gender. This study emphasizes the need to evaluate patients with diabetes mellitus for renal impairment so that intervention strategies may be adopted early to delay progression to endstage renal disease.

Adolescent↗
PubMed2003

Adrenal cortical phaeochromocytoma: a case report of a rare entity.

Adrenal cortical phaeochromocytomas (pseudo-phaeochromocytomas) are a very rare entity and a diagnostic challenge. Of the few cases previously reported, most have incomplete data or lack clinical and biochemical follow-up documenting the cure of the excess secretion of catecholamines after resection of the tumour. We report herein a 62-year-old patient with clinical and biochemical findings diagnostic of a phaeochromocytoma associated with a 2-cm adrenal mass on CT scan. Surgery revealed the presence of an adrenal cortical adenoma with positive staining for the neuroendocrine marker synaptophysin, but negative for chromogranin, as has been previously reported for these rare cortical phaeochromocytomas. After removal of the tumour the clinical symptoms resolved and biochemical markers normalized, demonstrating the causal relationship between the cortical tumour and the excess production of catecholamines.

Adrenal Cortex Neoplasms↗
PubMed2002

Multiple endocrine neoplasia 2A syndrome: Surgical management.

BACKGROUND/PURPOSE: Currently, molecular genetic diagnostics allow familial types of medullary thyroid carcinoma to be detected at an asymptomatic stage and surgery thus to be performed at a time when prognosis is good. The current report aims to determine the appropriate age for safe prophylactic thyroidectomy in children with multiple endocrine neoplasia (MEN) 2A and mutations at codon 609 according to genotype-phenotype correlations and will discuss surgical procedures. METHODS: The authors describe the case of a family with hereditary MEN 2A syndrome. A DNA analysis of 7 family members confirmed the diagnosis by a mutation at codon 609 of the RET proto-oncogene. RESULTS: A phaeochromocytoma developed in 2 family members. Four had medullary thyroid carcinoma. A grandson underwent a prophylactic thyroidectomy at the age of 5 on account of genetic evidence. Despite the negative preoperative and intraoperative findings he already had an invasive medullary thyroid carcinoma. CONCLUSIONS: Few genotype-phenotype correlations have been established for MEN 2A disease. According to the natural history of the disease, families with the genotype RET cys609gly should have a more benign disease than high-risk families (mutations at codon 634, 618). From this report the authors conclude that prophylactic thyroidectomy in "609" families should be performed earlier than actually recommended, favorably at the age of 2 to 4 years. Further multicenter studies are needed to provide more clinical and prognostic data for less frequent (codon 609, 630, 791, and 891) RET genotypes.

Adult↗
PubMed2002

Localization of hepatitis C virus RNA on human erythrocytes by RT in situ PCR technique.

BACKGROUND: Our previous results showed that hepatitis C virus (HCV) is detectable on erythrocytes by RT in situ PCR. The aims of the present study were to compare the sensitivity of this erythrocyte in situ PCR to routine serum solution phase HCV PCR as well as to obtain more data about the binding and cellular localization of HCV in the erythrocyte. METHODS: 105 previously HCV-infected patients and 20 control individuals were studied using RT in situ PCR on erythrocytes and solution phase RT-PCR from serum samples. Binding of HCV to erythrocytes was studied by in vitro inoculation. RT in situ PCR results were evaluated by fluorescence and confocal laser scanning microscopy. RESULTS: From 105 HCV cases, 78 gave positive, while 5-and all control cases-gave negative results by both PCR techniques. In 21 cases, only the in situ technique provided positive results, while in only I case did the solution phase method provide positive results. During in vitro inoculation, an early HCV-erythrocyte binding was detected followed by virus internalization. CONCLUSIONS: Erythrocyte-in situ PCR was found to show higher sensitivity for the detection of HCV compared to the generally applied serum PCR method. In vitro studies suggested a specific binding of HCV to erythrocyte and showed the virus to be capable of internalization.

Erythrocytes↗
PubMed2001

Rapid test for the preclinical postmortem diagnosis of BSE in central nervous system tissue.

The efficacy of a rapid test for detecting PrP(Sc) in central nervous system tissue was evaluated for the postmortem diagnosis of BSE at different times during the course of the disease. One hundred and six samples of brain, at the level of the medulla oblongata, and spinal cord, derived from the experimental study of the pathogenesis of BSE carried out in Great Britain between 1991 and 1995, were examined. PrP(Sc) was detected in the samples from most of the exposed animals killed 32 months or more after they had been exposed to the agent, and before the onset of clinical signs which were first recorded at 35 months. Comparisons with the results of histology, fibril detection, PrP immunohistochemistry and mouse bioassay indicated that the rapid test is at least as sensitive as these conventional confirmatory diagnostic methods and its result can be obtained more quickly.

Animals↗
PubMed2001

Quantitation and prevalence of tympanosclerosis in a pediatric otolaryngology clinic.

OBJECTIVE: To determine the incidence and prevalence of tympanosclerosis (TS) in patients seen in a pediatric otolaryngology clinic. DESIGN: Prospective observational study. SETTING: Tertiary care, ambulatory care clinic. PATIENTS AND OTHER PARTICIPANTS: We conducted a prospective observational study to determine the incidence of TS in 218 patients seen consecutively in a pediatric otolaryngology clinic for otologic and nonotologic reasons. The patient age range was 3 weeks to 30 years; 63% were male and 37% female. Of the 218 patients, 37% (81) had undergone bilateral myringotomy and tube placement (BM&T), and 35% (21) of the 81 showed signs of TS; 63% (137) of the 218 patients had no history of otologic surgery, but 12% (15) of the 137 showed signs of TS. METHOD: The area of the tympanic membrane affected by TS was determined by otoscopy performed by one viewer, who drew the otoscopic findings on a standardized tympanic membrane template. The area of TS was quantified in terms of percentages by digital image analysis of the scaled drawings. RESULTS: There was a range of 0.5-59.9% involvement of the tympanic membrane with TS, with the median percentage of involvement being 4.95%. There was an increased percentage of TS with repeat BM&T. CONCLUSION: This observational study shows that patients who have had BM&T have a higher incidence of TS than those who have not had the surgery. However our findings also show that 38% of the patients in this study who had TS had never undergone BM&T.

Adolescent↗
PubMed2001

The iodocyanopindolol and SM-11044 binding protein belongs to the TM9SF multispanning membrane protein superfamily.

SM-11044 is the only beta-adrenergic agonist that inhibits guinea pig eosinophil chemotaxis and induces relaxation of depolarized rat colon tonus. We have previously reported the purification of a 34 kDa photoaffinity-labeled SM-11044 binding protein (SMBP) from rat colon that may mediate the biological effects of the ligand and that differs from all known monoamine receptors (Sugasawa et al., J. Biol. Chem. 272 (1997) 21244). The present report describes partial amino acid sequence of rat SMBP and molecular cloning of corresponding human SMBP (hSMBP) cDNA. This cDNA encodes a 588 amino acid residue polypeptide comprising a signal peptide, a long hydrophilic amino-terminal region, and a highly hydrophobic C-terminal portion organized into nine putative transmembrane domains. The sequence and structure of hSMBP shows homology to members of a new transmembrane protein 9 superfamily (TM9SF). Comparison of hSMBP with related protein sequences from yeast, plant and human revealed two subgroups within TM9SF. The members of these groups differ in length and have characteristic amino acid sequence motifs in their amino-terminal portion. Northern blot analysis revealed two major SMBP mRNAs, at 3.4 and 3.8 kb, that were present in all the human tissues examined. Western blot experiments detected SMBP as a 70 kDa protein that may be further cleaved into an active 34 kDa N-terminal polypeptide. Stable Chinese Hamster Ovary cell transfectants expressing hSMBP cDNA displayed specific binding of [(125)I]iodocyanopindolol that was displaced by SM-11044 in a dose-dependent manner. Thus, SMBP is the first member of TM9SF with functional ligand binding properties, suggesting that some of these integral membrane proteins may function as channels, small molecule transporters or receptors.

Amino Acid Sequence↗
PubMed2001

Oral clearance and pathogenic oropharyngeal colonization in the elderly.

The elderly have an increased incidence of oropharyngeal colonization with respiratory pathogens, a well-known risk factor for the development of pneumonia. Changes in the oral milieu may occur secondary to decreased salivary production and abnormalities in swallowing. These abnormalities, common in the elderly, may result in impaired clearance of organisms, allowing pathogenic colonization. To test this hypothesis, we performed a prospective cross-sectional analysis of 75 elderly institutionalized patients and measured oral clearance using (99m)Tc-human serum albumin (HSA) administered to the oropharynx. Oropharyngeal cultures, salivary cell populations, elastase activity, and clinical parameters were measured simultaneously. Retention of radiolabel ranged from 100% to 2.3% over 120 min of observation. Clearance in the oropharynx was significantly decreased in those patients who had oropharyngeal colonization with gram-negative bacilli (GNB), Staphylococcus aureus (SA), or yeast compared with those demonstrating normal flora by 95% confidence intervals. Decreased clearance was also seen in patients on antidepressants by 95% confidence levels. The absolute number of salivary lymphocytes/ml and buccal cells/ml was increased in colonized patients versus noncolonized persons (mean +/- SEM, 128 x 10(3) +/- 49 x 10(3), 25.4 +/- 11.6 x 10(3)). Elastase activity was elevated in patients who had GNB compared with patients without GNB (mean +/- SEM, 10.6 nM +/- 5.7, versus 2.2 nM +/- 1.2, p = 0.036). We conclude that a decrease in salivary clearance of potentially pathogenic organisms may be a major risk factor for the development of colonization in the elderly.

Aged↗
PubMed2001

Chemically distinct transition states govern rapid dissociation of single L-selectin bonds under force.

Carbohydrate--protein bonds interrupt the rapid flow of leukocytes in the circulation by initiation of rolling and tethering at vessel walls. The cell surface carbohydrate ligands are glycosylated proteins like the mucin P-selectin glycoprotein ligand-1 (PSGL-1), which bind ubiquitously to the family of E-, P-, and L-selectin proteins in membranes of leukocytes and endothelium. The current view is that carbohydrate-selectin bonds dissociate a few times per second, and the unbinding rate increases weakly with force. However, such studies have provided little insight into how numerous hydrogen bonds, a Ca(2+) metal ion bond, and other interactions contribute to the mechanical strength of these attachments. Decorating a force probe with very dilute ligands and controlling touch to achieve rare single-bond events, we have varied the unbinding rates of carbohydrate--selectin bonds by detachment with ramps of force/time from 10 to 100,000 pN/sec. Testing PSGL-1, its outer 19 aa (19FT), and sialyl Lewis(X) (sLe(X)) against L-selectin in vitro on glass microspheres and in situ on neutrophils, we found that the unbinding rates followed the same dependence on force and increased by nearly 1,000-fold as rupture forces rose from a few to approximately 200 pN. Plotted on a logarithmic scale of loading rate, the rupture forces reveal two prominent energy barriers along the unbinding pathway. Strengths above 75 pN arise from rapid detachment (<0.01 sec) impeded by an inner barrier that requires a Ca(2+) bond between a single sLe(X) and the lectin domain. Strengths below 75 pN occur under slow detachment (>0.01 sec) impeded by the outer barrier, which appears to involve an array of weak (putatively hydrogen) bonds.

Calcium↗
PubMed2001

Massive gene decay in the leprosy bacillus.

Leprosy, a chronic human neurological disease, results from infection with the obligate intracellular pathogen Mycobacterium leprae, a close relative of the tubercle bacillus. Mycobacterium leprae has the longest doubling time of all known bacteria and has thwarted every effort at culture in the laboratory. Comparing the 3.27-megabase (Mb) genome sequence of an armadillo-derived Indian isolate of the leprosy bacillus with that of Mycobacterium tuberculosis (4.41 Mb) provides clear explanations for these properties and reveals an extreme case of reductive evolution. Less than half of the genome contains functional genes but pseudogenes, with intact counterparts in M. tuberculosis, abound. Genome downsizing and the current mosaic arrangement appear to have resulted from extensive recombination events between dispersed repetitive sequences. Gene deletion and decay have eliminated many important metabolic activities including siderophore production, part of the oxidative and most of the microaerophilic and anaerobic respiratory chains, and numerous catabolic systems and their regulatory circuits.

Animals↗
PubMed2001

The protein-protein interaction map of Helicobacter pylori.

With the availability of complete DNA sequences for many prokaryotic and eukaryotic genomes, and soon for the human genome itself, it is important to develop reliable proteome-wide approaches for a better understanding of protein function. As elementary constituents of cellular protein complexes and pathways, protein-protein interactions are key determinants of protein function. Here we have built a large-scale protein-protein interaction map of the human gastric pathogen Helicobacter pylori. We have used a high-throughput strategy of the yeast two-hybrid assay to screen 261 H. pylori proteins against a highly complex library of genome-encoded polypeptides. Over 1,200 interactions were identified between H. pylori proteins, connecting 46.6% of the proteome. The determination of a reliability score for every single protein-protein interaction and the identification of the actual interacting domains permitted the assignment of unannotated proteins to biological pathways.

Amino Acid Sequence↗