Measurement of the proton-air cross section at √s=57 TeV with the Pierre Auger Observatory.

We report a measurement of the proton-air cross section for particle production at the center-of-mass energy per nucleon of 57 TeV. This is derived from the distribution of the depths of shower maxima observed with the Pierre Auger Observatory: systematic uncertainties are studied in detail. Analyzing the tail of the distribution of the shower maxima, a proton-air cross section of [505±22(stat)(-36)(+28)(syst)] mb is found.

Measurement of the depth of maximum of extensive air showers above 10{18} eV.

We describe the measurement of the depth of maximum, X{max}, of the longitudinal development of air showers induced by cosmic rays. Almost 4000 events above 10;{18} eV observed by the fluorescence detector of the Pierre Auger Observatory in coincidence with at least one surface detector station are selected for the analysis. The average shower maximum was found to evolve with energy at a rate of (106{-21}{+35}) g/cm{2}/decade below 10{18.24+/-0.05} eV, and (24+/-3) g/cm{2}/decade above this energy. The measured shower-to-shower fluctuations decrease from about 55 to 26 g/cm{2}. The interpretation of these results in terms of the cosmic ray mass composition is briefly discussed.

Faecal indicator bacteria in river biofilms.

Biofilms in surface waters primarily consist of allochthonous microorganisms. Under conditions of pollution faecally derived bacteria may interact with these biofilms. Total coliform bacteria, Escherichia coli and intestinal enterococci are used to monitor source water quality, indicating faecal pollution and the possible presence of enteric pathogens. In the present study the occurrence of faecal indicators was investigated in biofilms (epilithic biofilms, sediments) of German rivers. All of the biofilms contained significant concentrations of these bacteria, which were several orders of magnitude lower compared with the total cell number and the number of culturable heterotrophic plate count bacteria indicating that faecal indicator bacteria represented a minor fraction of the whole biofilm communities. The biofilms displayed approximately two orders of magnitude higher concentrations of total coliforms, E. coli and enterococci compared with the overlying water. Identification of coliform and enterococcal isolates from the biofilms revealed the presence of species which are known to be opportunistic pathogens. Overall, the results of the present study show that faecal indicator bacteria can survive in the presence of high cell densities of the authochthonous microflora in epilithic biofilms and sediments, suggesting that these biofilms may act as a reservoir for bacterial pathogens in polluted rivers.

Degradation of heterocyclic aromatic amines in oil under storage and frying conditions and reduction of their mutagenic potential.

Heterocyclic aromatic amines (HAA) were systematically studied concerning their partition behavior in water/oil-systems and their thermostability in different animal derived fats and vegetable oils. Partitioning of IQx-compounds and PhIP in water/oil systems was found to depend on the polarity defined by the molecular structure and on the pH-value of the aqueous phase. In particular, beta-carbolines norharman and harman showed a significant strong lipophilic character at alkaline pH. After heating in frying fats at 130 degrees C, contents of IQx compounds and PhIP were reduced by more than 40% and after heating at 180 degrees C less than 10% of the HAA initial concentration was recovered. By contrast, norharman and harman were much more stable under equivalent conditions. The present study leads for the first time to the conclusion that degradation of HAA in frying fats strongly correlates to the type of frying fat and is promoted by lipid oxidation products. Firstly, addition of hydroperoxides to model oils lead to a decrease of HAA during storage at 40 degrees C. Secondly, stability of HAA correlated with the content of unsaturated fatty acids in the oil, which is indicative for the oxidative stability of the medium. Degradation of HAA by heat treatment was associated with a reduction of their mutagenic potential towards strain TA98 of Salmonella typhimurium.

Mutations in the leader region of ribosomal RNA operons cause structurally defective 30 S ribosomes as revealed by in vivo structural probing.

The biogenesis of functional ribosomes is regulated in a very complex manner, involving different proteins and RNA molecules. RNAs are not only essential components of both ribosomal subunits but also transiently interacting factors during particle formation. In eukaryotes snoRNAs act as molecular chaperones to assist maturation, modification and assembly. In a very similar way highly conserved leader sequences of bacterial rRNA operons are involved in the correct formation of 30 S ribosomal subunits. Certain mutations in the rRNA leader region cause severe growth defects due to malfunction of ribosomes which are assembled from such transcription units. To understand how the leader sequences act to facilitate the formation of the correct 30 S subunits we performed in vivo chemical probing to assess structural differences between ribosomes assembled either from rRNA transcribed from wild-type operons or from operons which contain mutations in the rRNA leader region. Cells transformed with plasmids containing the respective rRNA operons were reacted with dimethylsulphate (DMS). Ribosomes were isolated by sucrose gradient centrifugation and modified nucleotides within the 16 S rRNA were identified by primer extension reaction. Structural differences between ribosomes from wild-type and mutant rRNA operons occur in several clusters within the 16 S rRNA secondary structure. The most prominent differences are located in the central domain including the universally conserved pseudoknot structure which connects the 5', the central and the 3' domain of 16 S rRNA. Two other clusters with structural differences fall in the 5' domain where the leader had been shown to interact with mature 16 S rRNA and within the ribosomal protein S4 binding site. The other differences in structure are located in sites which are also known as sites for the action of several antibiotics. The data explain the functional defects of ribosomes from rRNA operons with leader mutations and help to understand the altered biogenesis pathway from mutations in an rRNA leader region to the formation of functionally defective ribosomes.

Evidence for a role of Trp proteins in the oxidative stress-induced membrane conductances of porcine aortic endothelial cells.

OBJECTIVE: Expression of homologues of the Drosophila transient receptor potential (Trp) protein has recently been demonstrated for vascular endothelium. Some Trp isoforms such as Trp3, are known to constitute cation conductances with biophysical properties similar to those of the endothelial oxidant-activated cation conductance. Therefore we tested whether Trp proteins provide the molecular basis of the oxidant-induced membrane currents in porcine aortic endothelial cells (ECAP). METHODS: Expression of the Trp3 isoform in ECAP was tested by RT-PCR and subsequent southern blot analysis. In order to knock-out the function of endogenous Trp channels, ECAP were transiently transfected to express NTRP3, a dominant negative fragment of Trp3. Oxidative-stress was introduced by exposure of cells to tert-butylhydroperoxide (tBHP; 400 microM), and membrane current as well as membrane potential were recorded using the conventional whole cell patch-clamp technique. RESULTS: RT-PCR experiments demonstrated the expression of a Trp3 isoform in ECAP. The oxidant tert.-butylhydroperoxide (tBHP) completely depolarized endothelial cells by activation of a cation conductance which allowed significant Na+ inward currents at negative potentials (mean inward current 462 pA at -80 mV). The tBHP-induced currents resembled Trp-related currents in terms of cation selectivity, La3+ sensitivity and lack of voltage dependence. Expression of the N-terminal fragment of hTrp3 (NTRP3), but not of a C-terminal fragment of hTrp3 (CTRP3), abolished the oxidant-induced cation current and reduced membrane depolarization. CONCLUSION: Our results strongly suggest Trp proteins as the molecular basis of endothelial oxidant-activated cation channels. It is concluded that Trp proteins play an important role in the redox sensitivity of the vascular endothelium.

Trp proteins form store-operated cation channels in human vascular endothelial cells.

Members of the Trp protein family have been suggested as the structural basis of store-operated cation conductances. With this study, we provide evidence for the expression of three isoforms of Trp (hTrp1, 3 and 4) in human umbilical vein endothelial cells (HUVEC). The role of Trp proteins in store regulation of endothelial membrane conductances was tested by expression of an N-terminal fragment of hTrp3 (N-TRP) which exerts a dominant negative effect on Trp channel function presumably due to suppression of channel assembly. Depletion of intracellular Ca2+ stores with IP3 (100 microM) or thapsigargin (100 nM) induced a substantial cation conductance in sham-transfected HUVEC as well as in HUVEC transfected with hTrp3. In contrast, HUVEC transfected with N-TRP failed to exhibit store-operated currents. Our results suggest the involvement of Trp related proteins in the store-operated cation conductance of human vascular endothelial cells.

Behind shamanism: changing voices of Siberian Khanty cosmology and politics.

Siberian shamanism has roots in hunting traditions, kinship organization and soul beliefs which have changed under Soviet rule. Aspects of shamanic epistemology and curing survive, although native medical logic sometimes clashes with modern positivist medicine. Assumptions behind Siberian, particularly Khanty, shamanism are examined through analysis of training, seances and cosmology. The changing social context of shamanism is explored in a framework of Soviet pressure to reject shamanic 'superstitution' and 'exploration.' Shamans themselves have adapted their politics, diagnoses and symbolic actions to an increasingly cold social climate. Data results from ethno-historical and field research, including a summer 1975 trip to the Ob-Ugrian Khanty (Ostiak).

Composite keratohyaline granules in palmoplantar keratoderma: an ultrastructural study.

We report the results of an ultrastructural study of the hyperkeratotic epidermis in 23 cases of palmoplantar keratoderma (PPK) comprising 8 inherited keratoderma, 8 keratoderma climactericum in menopausal women and 7 symptomatic keratoderma. In all but one of the cases of inherited PPK and keratoderma climactericum, composite keratohyalin (KH) granules were found in granular cells of the interductal epidermis, which were similar to those found in the rat and in some other conditions. In the cases of symptomatic keratoderma, e.g. secondary to eczema, the appearance of the KH granules did not differ from that of granules observed in two normal plantar skin samples. While the real role played by these granules is unknown, they could constitute a differentiation marker of intraepidermal duct cells, and their abundance in PPK suggest that intraepidermal sweat ducts may play a part in PPK histogenesis.

Cryopreservation of human fetal organs.

The effects of low temperature preservation on morphology, viability and differentiation capacity of different human fetal organs were studied using transmission (TEM) and scanning (SEM) electron microscopy, in vitro cultivation as well as xenogeneic transplantation. For this purpose fragments of lung, kidney, small intestine, thyroid, brain, liver and spleen from 10 human fetuses (aged 9 to 14 weeks of gestation) were frozen by a three step cooling procedure. After 3 to 12 months the specimens were thawed rapidly and processed for TEM and/or in vitro cultivation and/or transplantation into nude mice. TEM studies on frozen lung, kidney and intestine revealed generally a well preserved ultrastructure whereas liver and spleen fragments appeared highly necrotic. From three fetuses, frozen intestine and lung specimens were used for the establishment of monolayer cultures. Following trypsinization, both epithelial and mesenchymal cells formed a continuous layer on the bottom of plastic bottles. During further subpassages the number of epithelial cells decreased resulting in the formation of pure fibroblast cultures. Frozen brain tissue from one fetus was also successfully cultivated forming cell clusters and fiber bundles of variable size at the surface of glass cover slips. Following subcutaneous implantation into nude mice, the vast majority of fragments from lung, kidney, intestine and thyroid was found to grow in the recipients. The growth of xenografts was accompanied by persistence (kidney, intestine) or even increase (lung, thyroid) in cellular differentiation studied by TEM or autoradiography. Transplanted liver and spleen fragments, however, regularly regressed forming solid scars in the subcutaneous tissue of nude mice.(ABSTRACT TRUNCATED AT 250 WORDS)

[Morphology and physiopathology of Billroth I gastroduodenostomy]. / Morfologia e fisiopatologia della gastroduodenostomia secondo Billroth I

97 patients subjected from 1 to 7 years previously to partial gastric resection by gastroduodenostomy (Billroth I) have been studied endoscopically and radiologically. Acid secretion after pentagastrin injection has also been determined. The most frequent mucous alterations identified by endoscopy were erosions in the stomach residue with inflammatory granulation in the anastomosis region. Recurrent ulcers were observed in 3% of cases. Acid secretion was reduced in 87% by comparison with the preoperative picture. The quantity of residual recretion depended on the greater curvature of the residual stomach. Radiological studies highlighted functional modifications indicative of organized motility in the residual stomach and pseudopyloric function at anastomosis level making coordinated draining possible.

[Relevance of MRI for endometriosis diagnosis]. / Stellenwert der Magnetresonanztomografie in der Diagnostik der Endometriose.

Endometriosis is a disease of the uterus with displacement of endometrium-like tissue outside the endometrium. Endometriosis is a common benign chronic often debilitating disease that primarily affects young woman. The estimated prevalence is about 10 %. In addition to the uterus and ovaries, clinically important localisations are the rectovaginal space, rectum, sigmoid colon, urinary bladder, ureter and peritoneum. The most common localisation outside the pelvis is the abdominal wall. Today, MRI is one of the most important tools in the diagnosis of endometriosis. The detection of peritoneal manifestations and the exact definition of the depth of infiltration in the rectum, sigmoid colon and bladder walls are limitations of MRI.

Assessment of the older female surgical patient.

Many older women enjoy better health than ever. Improved health care for women creates populations of older women who also have mental illness, chronic illness, are mentally impaired, or have dementia. Although aging itself may not be considered a surgical risk, those coexisting conditions predispose many older women to be vulnerable or at risk for a surgical procedure. A few of the major problems recounted by caregivers are reviewed here. Among them are disorientation, incontinence, and decubitus ulcers.

[Morphology and pathophysiology of Billroth I gastro-duodenostomy (author's transl)]. / Der Billroth-I-Magen. Beitrag zur Morphologie und Pathophysiologie

Endoscopic and radiological studies were undertaken in 97 patients who had had a partial gastric resection with gastro-duodenostomy (Billroth I) one to seven years previously. Acid secretion was also analyzed after injection of pentagastrin. The most frequent mucosal changes seen at endoscopy were erosion in the residual stomach, with inflammatory granulation in the region of the anastomosis. Recurrent ulcers were seen in 3%. Acid secretion was reduced by 87% from its pre-operative level. The amount of residual secretion depended on the length of the greater curvature in the residual stomach. Radiological studies revealed functional changes indicating that there is a motility pattern in the residual stomach and a pseudopyloric function at the anastomosis which makes co-ordinated emptying possible.

Expression of cellular effector functions and production of reactive nitrogen intermediates: a comparative study including T lymphocytes, T-like cells, neutrophil granulocytes, and mononuclear phagocytes.

The ability of various cell types to secrete reactive nitrogen intermediates (RNI) upon functional activation was comparatively assessed. Neither in T lymphocyte clones mediating MHC class I or class II antigen-restricted killing via alpha/beta T cell receptor (TcR) or MHC-unrestricted killing via gamma/delta TcR, nor in peripheral blood mononuclear cells expressing natural killer or lymphokine-activated killer activity, target cell lysis was associated with detectable RNI production. Also, activated neutrophil granulocytes did not secrete RNI. In contrast, bone marrow-derived mononuclear phagocytes, activated to express tumoricidal activity, secreted marked RNI activity.