Quantitative Bestimmung von Pregnandiol

Ohne Zusammenfassung     

Human papillomavirus-positive tonsillar carcinomas: a different tumor entity?

Human papillomavirus (HPV) infections are thought to be one of the causal factors in the development of head and neck squamous cell carcinomas (HNSCC), particularly in tumors arising from the Waldeyer's tonsillar ring. We screened 98 carefully stratified HNSCC and different control tissues for the presence of HPV DNA by nested polymerase chain reaction (PCR) specific for genital- and Epidermodysplasia verruciformis (EV)-associated HPVs and by HPV16-specific single step PCR. Typing was performed by direct sequencing and/or sequencing of cloned amplimers. On average HNSCC showed rather low HPV DNA prevalences; 18% of the oral cavity cancers, 8% of nasopharyngeal cancers, 25% of hypopharyngeal cancers and 7% of laryngeal cancers were HPV DNA positive. In contrast, HPV sequences could be detected in 45% of the oropharyngeal cancers, particularly tonsillar carcinomas (58%). Tonsillar carcinomas were significantly more likely to be HPV positive than tumors from any other site ( P<0.001). All tonsillar cancers contained oncogenic HPV types, predominantly HPV16 (13 of 14; 93%). Unaffected tonsils were available from two of these patients, but both tested negative for HPV DNA. Furthermore, no HPV DNA could be found in tonsillar biopsy specimens from control groups. Localization and load of HPV DNA was determined in HPV16-positive tonsillar carcinomas, their metastases and in unaffected mucosa using laser-assisted microdissection and subsequent real time fluorescence PCR. We demonstrated that the HPV genome is located in the cancer cells, whereas the infection of normal mucosa is a rare event. Quantification of HPV16 DNA in samples of seven patients yielded viral loads from 6 to 153 HPV DNA copies per beta-globin gene copy and the load values in both locations were roughly comparable. These loads are comparable with data shown for other HPV-associated lesions. Statistical evaluation of data related to clinicopathological parameters showed a significant correlation of the HPV positivity of tonsillar carcinomas with tumor grading ( P=0.008) and alcohol consumption ( P=0.029). Taken together our findings show a preferential association of HPV DNA with tonsillar carcinomas. Furthermore our results argue for HPV-positive tonsillar carcinomas representing a separate tumor entity, which is less dependent on conventional HNSCC risk factors.     

Fetal development in experimental uremia

Summary Uremic women on hemodialysis with metabolic bone disease (hyperparathyroidism, osteomalacia resulting from defective vitamin D metabolism) and anemia (erythropoietin deficiency) are known to give birth to infants without bone disease or anemia. Therefore, skeletal development (enchondral and desmal bone formation) and hepatic erythropoiesis were evaluated in fetuses of uremic rats. These fetuses failed to show defective mineralisation or evidence of bone disease. Bolus injection of high doses of exogenous PTH into the maternal or fetal organism did not affect fetal bone histology. In addition, no apparent defect of bone mineralisation or bone formation was found in fetuses of ricketic rats. Normal mineralisation in the offspring of uremic rats may be explained by fetal hyperphosphatemia and/or insensitivity of fetal (woven) bone mineralisation to vitamin D.Absence of fetal anemia (normal hematocrits, normal density of hematopoietic cells in the liver) in the presence of maternal anemia is presumably due to the insensitivity of fetal erythropoiesis to erythropoietin.With the support of Deutsche Forschungsgemeinschaft     

Ionic conductances of cultured principal cell epithelium of renal collecting duct

The ionic conductive properties were studied of epithelia of collecting duct principal cells which had been grown in primary tissue culture from renal cortex/capsule explants. When pretreated with aldosterone (10^–6 mol/l) and bathed on either surface with isotonic HCO ₃ ^– -free Ringer's solution, the transepithelial voltage,V _te, varied between –21 and –72 mV (apical surface negative) while the transepithelial resistance,R _te, ranged from 0.4 to 1.5 kcm². By 10:1 step-changes in Na⁺ concentration the apical cell membrane was shown to have a high conductivity for sodium, inhibitable by amiloride, 10^–6 mol/l. However, contrary to observations in natural collecting duct under control conditions, amiloride never reversed the polarity ofV _te even at 10^–4 mol/l. Both the apical and the basolateral cell membranes were conductive for potassium and both conductivities were inhibitable by Ba²⁺ (5 mmol/l). 10:1 reduction of apical Cl^– concentration strongly hyperpolarizedV _te with a monophasic time course suggesting the presence of a paracellular shunt conductance for Cl^–. In addition there may be a small Cl^– conductance present in the apical cell membrane since apical application of the chloride channel blocker 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPAB) at 10^–7 mol/l produced a minute but significant hyperpolarization. On the other hand, 10:1 reduction of basolateral Cl^– concentration caused a biphasic change inV _te (initial depolarization, followed by repolarization) which indicates the presence of a large Cl^– conductance in the basolateral cell membrane. The latter was not inhibitable by 10^–7 mol/l NPPAB. Higher concentrations of this and of an other Cl^– channel blocker produced non-specific effects. In conclusion, our studies of a pure principal cell epithelium confirm findings described for the intact cortical collecting duct and add new information concerning chloride conductivity and related blocking agents.Dedicated to Prof. Dr. H. Sitte, Homburg, FRG, upon his 60th birthday.     

Differences of E-cadherin expression levels and patterns in primary and metastatic human lung cancer

Normal lung epithelium and 52 lung carcinomas obtained at surgical resection were examined by immunofluorescence for their expression levels and patterns of the calcium-dependent intercellular adhesion molecule E-cadherin. In dysplastic lung tissue and in well-differentiated squamous cell and adenocarcinomas, expression of E-cadherin was confined to the lateral cell border, similar to the expression level and pattern of normal lung tissue. The E-cadherin level was reduced and expression pattern was spotty or diffuse in moderately and poorly differentiated squamous cell and in small cell carcinomas of the lung. Most metastases resected also had a reduced level and an altered pattern of E-cadherin expression. In contrast, no such correlation was found in adenocarcinomas of the lung. This indicates that different cellular mechanisms are responsible in the progression of squamous cell carcinomas and adenocarcinomas of the lung.     

Fast network oscillations in the rat dentate gyrus in vitro

The dentate gyrus is a prominent source of gamma frequency activity in the hippocampal formation in vivo. Here we show that transient epochs of gamma frequency network activity (67 +/- 12 Hz) can be generated in the dentate gyrus of rat hippocampal slices, following brief pressure ejections of a high-molarity potassium solution onto the molecular layer. Oscillatory activity remains synchronized over distances >300 microm and is accompanied by a modest rise in [K(+)](o). Gamma frequency oscillations were abolished by a GABA(A) receptor antagonist demonstrating their dependence on rhythmic inhibition. However, in many cases, higher frequency oscillations (>80 Hz) remained in the absence of synaptic transmission, thus demonstrating that nonsynaptic factors may underlie fast oscillatory activity.     

Differential regulation of osteoblasts by substrate microstructural features

Microtextured titanium implant surfaces enhance bone formation in vivo and osteoblast phenotypic expression in vitro, but the mechanisms are not understood. To determine the roles of specific microarchitectural features in modulating osteoblast behavior, we used Ti surfaces prepared by electrochemical micromachining as substrates for MG63 osteoblast-like cell culture. Cell response was compared to tissue culture plastic, a sand-blasted with large grit and acid-etched surface with defined mixed microtopography (SLA), polished Ti surfaces, and polished surfaces electrochemically machined through a photoresist pattern to produce cavities with 100, 30 and 10 microm diameters arranged so that the ratio of the microscopic-scale area of the cavities versus the microscopic-scale area of the flat region between the cavities was equal to 1 or 6. Microstructured disks were acid-etched, producing overall sub-micron-scale roughness (Ra=0.7 microm). Cell number, differentiation (alkaline phosphatase; osteocalcin) and local factor levels (TGF-beta1; PGE(2)) varied with microarchitecture. 100 microm cavities favored osteoblast attachment and growth, the sub-micron-scale etch enhanced differentiation and TGF-beta1 production, whereas PGE(2) depended on cavity dimensions but not the sub-micron-scale roughness.