julilili42/papers huggingface dataset:
The record of Periadriatic volcanism in the Eastern Alpine Molasse zone and its palaeogeographic implications
2000-02-01

Precise provenance analysis of andesite and dacite pebbles from conglomerates in the Eastern Alpine Molasse zone, using geochemical and geochronological methods, provides evidence for a synorogenic volcanic chain in the Eastern Alps which is completely eroded today. This volcanism was related to Periadriatic magmatism along the Periadriatic lineament and took place in the Palaeogene, roughly between 40 and 30 Ma. The occurrence of remnants of these volcanic rocks together with other marker lithologies in the Eastern Alpine Molasse, implies an early to middle Miocene drainage system which was, in some respects, similar to the present Inn river system, but had a considerably larger catchment area, reaching farther south. The Palaeo‐Inn drained the central and eastern sections of the Periadriatic magmatic belt to the northern foreland basin.
Observations on the structure of larval attachment organs in three species of gymnotiforms (Teleostei: Ostariophysi)
2000-02-01

Attachment organs are known in certain teleosts but have not been reported in gymnotiforms. This study demonstrates the presence and describes the structure of attachment organs in three species of gymnotiforms: the apteronotids Apteronotus albifrons and A. leptorhynchus , and the rhamphichthyid Rhamphichthys sp. Attachment organs are present only during the first few days after hatching. Organs were studied with light microscopy, SEM, and TEM. In all three species attachment organs are restricted to the head region. They consist of numerous individual attachment cells and modified epithelial cells distributed on the frontal, lateral, and dorsal head area. Only the apical parts of the attachment cells reach the body surface between the epithelium of the epidermis. Attachment cells contain considerable amounts of rough ER and Golgi vesicles filled a the glutinous substance. Epithelial cells in the area in which attachment cells are developed differ in structure from those on the rest of the body and form a functional complex with the attachment cells. In the two Apteronotus species they possess 4–10 μm long projections that are located in the cell centre in A. albifrons , but are slightly shifted to one side of the cells in A. leptorhynchus . Epithelial cells in the organ area of Rhamphichthys sp. lack any projections and resemble cells of the trunk region. However, their pattern of microridges on the outer cell surface is more pronounced and conspicuous. Projections along with modified microridges may aid in distributing and focusing adhesive substances released by attachment cells, and thus may enhance adhesive properties.
High resolution solution structure of the protein part of Cu7 metallothionein
2000-02-01

The three‐dimensional solution structure of the protein part of Cu7 metallothionein (Cu 7 MT) of Saccharomyces cerevisiae has been attempted by 1 H two‐dimensional NMR spectroscopy at 800 MHz. The protein part constitutes 53 amino acids. A total of 1192 NOEs, of which 1048 are meaningful, were used to determine the solution structure of the first 40 residues, the last 13 residues being disordered. A family of 30 structures was generated. Root‐mean‐square deviation (rmsd) values from the average structure of 0.32 ± 0.13 Å and 0.61 ± 0.15 Å for backbone and all heavy atoms, respectively, were obtained for the residues 2–40. The ten copper‐coordinating cysteine sulfurs and the empty spaces around them are well defined. The structure of the protein part is similar but not identical to the available ones of the same holoprotein and of the Ag 7 metallothionein, and is qualitatively superior. If the same metal–sulfur connectivities reported in the literature from 1 H‐ 109 Ag heteronuclear multiple quantum coherence spectroscopy are assumed to hold for the present copper derivative, a peptide structure is obtained which is again similar, but still not identical, within indetermination, to that available. The structure of the copper polymetallic center may well be different from that proposed for the silver derivative, and indeed a number of different arrangements of the seven copper ions are consistent with the present highly refined structure of the protein part.
The Significance of Preformed Aprotinin-Specific Antibodies in Cardiosurgical Patients
2000-02-01

Acute hypersensitivity reactions are serious complications of reexposure to aprotinin. Previous contact via infusions or fibrin tissue adhesives can induce specific antibodies. In this study, we aimed to elucidate the preoperative prevalence of aprotinin-specific antibodies in patients scheduled for cardiac operations. Sera of 520 consecutive cardiosurgical patients were collected preoperatively and screened retrospectively for aprotinin-specific IgG using a standard enzyme-linked immunosorbent assay (ELISA). Positive sera were analyzed also for aprotinin-specific IgA (ELISA) and IgE (fluorescence enzyme immunoassay). The histories of all patients were reviewed with focus on aprotinin preexposure. Of 520 patients, 22 (4%) had specific IgG. Only three of these had a documented aprotinin preexposure. Of 448 patients exposed to aprotinin intraoperatively, 15 had preformed specific antibodies. The only patient presenting with severe anaphylaxis was positive for both IgG and IgE, and had a recent IV preexposure in cardiovascular surgery. The presence of aprotinin-specific IgG alone seems not to induce adverse reactions on exposure. Exposure history alone is not sensitive enough to identify patients with aprotinin-specific antibodies. Implications Anaphylaxis on IV reexposure to aprotinin is a medical emergency. The clinical significance of preformed aprotinin-specific IgG remains questionable, whereas preformed IgE was present in the only patient who suffered from severe anaphylaxis on reexposure to aprotinin. Preformed antibodies are not reliably predicted by exposure history.
Reversal of Hypoglycemia Unawareness in a Long-Term Type 1 Diabetic Patient by Improvement of β-Adrenergic Sensitivity after Prevention of Hypoglycemia
2000-02-01

The purpose of this study was to assess the effect of strict avoidance of hypoglycemia on beta-adrenergic sensitivity in a type 1 diabetic patient with hypoglycemia unawareness and a diabetes duration of 55 yr. beta-Adrenergic sensitivity was determined by an isoproterenol test and was expressed as the lowest dose of isoproterenol that increases the heart rate by 25 beats/min (IC25). Plasma epinephrine and symptom responses to hypoglycemia were determined during a 3-h hypoglycemic (3 mmol/L) clamp. Initially, the patient had a near-normal counterregulatory plasma epinephrine response to hypoglycemia but reduced beta-adrenergic sensitivity (IC25, 2 microg) compared to 10 hypoglycemia aware, type 1 diabetic patients (0.65 +/- 0.14 microg) and 10 normal control subjects (1.13 +/- 0.21 microg). After 1 yr of strict avoidance of blood glucose levels below 4 mmol/L, the IC25 decreased to 0.25 microg, reflecting improved beta-adrenergic sensitivity. In conclusion, the reduced beta-adrenergic sensitivity in this patient was probably the reason for hypoglycemia unawareness and was reversed by strict avoidance of hypoglycemia.
Melanocytes in nevi and melanomas synthesize basement membrane and basement membrane‐like material. An immunohistochemical and electron microscopic study including immunoelectron microscopy
2000-02-01

Light microscopic studies have shown that nevus cell nests and melanoma nests are surrounded by basement membrane (BM) material containing type IV collagen and laminin. This study confirms this by electron microscopy and relates it to proteins which interact with the basement membrane. Nevi except for dysplastic and Spitz nevi, malignant melanomas, and melanoma metastases were studied by immunohistopathology, routine electron microscopy (EM), and immunoelectron microscopy. The lesions were incubated with monoclonal antibody (moAb) against type IV collagen, laminin, and the integrin α 6 and studied by light microscopy. In addition, melanomas were studied by immuno‐EM after incubation with a moAb against matrix metalloproteinase‐2 (MMP‐2). Nevus cell nests and melanoma nests are surrounded by BM material containing type IV collagen and laminin by immuno‐EM. The BM material various in thickness and is amorphous. Type IV collagen, laminin, and MMP‐2 are synthesized by melanoma cells as well as adjacent fibroblasts. Destruction or loss of the BM is not mandatory for melanoma invasion or even metastasis. Possibly the BM material is a protective wall for melanoma cells. Interactions between melanocytes and the extracellular matrix of which the BM is a part, can be traced back to the migration of melanocytes from the neural crest.
Localization of S-adenosylhomocysteine Hydrolase in the Rat Kidney
2000-02-01

S-adenosylhomocysteine (SAH) hydrolase is a cytosolic enzyme present in the kidney. Enzyme activities of SAH hydrolase were measured in the kidney in isolated glomeruli and tubules. SAH hydrolase activity was 0.62 ± 0.02 mU/mg in the kidney, 0.32 ± 0.03 mU/mg in the glomeruli, and 0.50 ± 0.02 mU/mg in isolated tubules. Using immunohistochemical methods, we describe the localization of the enzyme SAH hydrolase in rat kidney with a highly specific antibody raised in rabbits against purified SAH hydrolase from bovine kidney. This antibody crossreacts to almost the same extent with the SAH hydrolase from different species such as rat, pig, and human. Using light microscopy, SAH hydrolase was visualized by the biotin-streptavidin-alkaline phosphatase immunohistochemical procedure. SAH hydrolase immunostaining was observed in glomeruli and in the epithelium of the proximal and distal tubules. The collecting ducts of the cortex and medulla were homogeneously stained. By using double immunofluorescence staining and two-channel immunofluorescence confocal laser scanning microscopy, we differentiated the glomerular cells (endothelium, mesangium, podocytes) and found intensive staining of podocytes. Our results show that the enzyme SAH hydrolase is found ubiquitously in the rat kidney. The prominent staining of SAH hydrolase in the podocytes may reflect high rates of transmethylation.
Optimal Policy for Financial Market Liberalizations: Decentralization and Capital Flow Reversals
2000-02-01

Abstract Financial market liberalizations are an integral part of economic development. While initial booms in investment and output are commonly seen as signs of successful deregulation, they often reverse at a later stage as international capital flows turn negative and economic growth slows markedly. Such reversals of fortunes have commonly been attributed to incorrect policies that supposedly followed the initial, appropriate measures. It is unclear, however, if capital flow reversals are actually the result of policy reversals, or if they occur as part of the normal transition when financial liberalization is accompanied by a single suboptimal policy. The later hypothesis has not been explored in the theoretical literature. We construct a general equilibrium growth model of a small open economy, in which capital flow reversals are the result of a single, suboptimal policy imposed at the beginning of the financial liberalization. We show how improper taxation of foreign borrowing initially leads to strong growth fuelled by an investment boom and foreign borrowing. Still along the transition, however, the model predicts that capital flows must reverse endogenously at a later stage, as the debt burden rises and the country-specific risk premium increases. Our data on the Latin American and East Asian countries provide strong support for our hypothesis.
The gastric H,K‐ATPase blocker lansoprazole is an inhibitor of chloride channels
2000-02-01

It was postulated that swelling dependent chloride channels are involved in the proton secretion of parietal cells. Since omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 are structurally related to phenol derivatives known to block swelling dependent chloride channels, we set out to test, whether these substances – which are known to block the H,K‐ATPase – could also lead to an inhibition of swelling‐dependent chloride channels. Swelling‐dependent chloride channels – characterized in many different cell types – show highly conserved biophysical and pharmacological features, therefore we investigated the effect of omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 on swelling‐dependent chloride channels elicited in fibroblasts, after the reduction of the extracellular osmolarity. Omeprazole, lansoprazole and its acid activated sulphenamide form AG2000 are able to block swelling‐dependent chloride channels (IClswell). Lansoprazole and its protonated metabolite AG2000 act on at least two different sites of the IClswell protein: on an extracellular site which seems to be in a functional proximity to the nucleotide binding site, and on an intracellular site which allows the formation of disulfide‐bridges. The inhibition of the proton pump and the simultaneous blocking of chloride channels by omeprazole, lansoprazole and its acid activated sulphenamide form AG2000, as described here could be an effective mode to restrict proton secretion in parietal cells. British Journal of Pharmacology (2000) 129 , 598–604; doi: 10.1038/sj.bjp.0703070
Trefoil factor family domain peptides in the human respiratory tract
2000-02-01

Trefoil factor family domain peptides (TFF) are thought to be involved in mucosal epithelial restitution and wound healing of the gastrointestinal tract and are up-regulated in ulceration and in a variety of solid tumours. It was hypothesized that TFFs are also expressed on mucosal surfaces of the human respiratory tract. Lung tissue, nasal polyps, and sputum samples from seven patients with cystic fibrosis (CF), two with chronic and acute bronchitis, and non-dysplastic material from two cases of bronchial adenocarcinoma were analysed for TFF expression by immunohistochemistry, immunofluorescence, western blot and RT-PCR. Expression of TFF1 and TFF3 was observed in material from all patients. TFFs were localized in goblet and ciliated cells, as well as in some submucosal cells of tracheobronchial tissues and nasal polyps from normal and CF individuals. In sputa of patients with CF and with chronic or acute bronchitis, TFF1 and TFF3 were detected by western blotting. Freshly cultivated nasal epithelial cells transcribed and secreted TFFs and mucins, whereas nasal cells cultivated for 6 weeks still expressed mucins, but not TFFs. Secreted TFFs and mucins also bound to the surface of Staphylococcus aureus in infected CF airways. In conclusion, TFF1 and TFF3 are expressed and secreted in normal and inflamed airways. The association of TFFs with bacteria may contribute to the anti-microbial mucociliary defence system. Copyright © 2000 John Wiley & Sons, Ltd.
Multispecific CD4+ T Cell Response to a Single 12-mer Epitope of the Immunodominant Heat-Shock Protein 60 ofYersinia enterocoliticainYersinia-Triggered Reactive Arthritis: Overlap with the B27-Restricted CD8 Epitope, Functional Properties, and Epitope Presentation by Multiple DR Alleles
2000-02-01

Abstract Yersinia heat-shock protein 60 (Ye-hsp60) has recently been found to be a dominant CD4 and CD8 T cell Ag in Yersinia-triggered reactive arthritis. The nature of this response with respect to the epitopes recognized and functional characteristics of the T cells is largely unknown. CD4+ T cell clones specific for Ye-hsp60 were raised from synovial fluid mononuclear cells from a patient with Yersinia-triggered reactive arthritis. and their specificity was determined using three recombinant Ye-hsp60 fragments, overlapping 18-mer synthetic peptides as well as truncated peptides. Functional characteristics were assessed by cytokine secretion analysis in culture supernatants after specific antigenic stimulation. Amino acid positions relevant for T cell activation were detected by single alanine substitutions within the epitopes. Fragment II comprising amino acid sequence 182–371 was recognized by the majority of clones. All these clones were specific for peptide 319–342. Th1 clones and IL-10-secreting clones occurred in parallel, sometimes with the same fine specificity. The 12-mer core epitope 322–333 is a degenerate MHC binder and is presented to some T cell clones in a “promiscuous” manner. This epitope is almost identical with a B27-restricted CTL epitope of Ye-hsp60. Cross-reactivity of Ye-hsp60-specific T cell clones with self-hsp60 was not observed. In conclusion, an interesting Ye-hsp60 T cell epitope has been identified and characterized. It remains to be determined whether this epitope is also relevant in other reactive arthritis patients.
Conserved Tyr residues determine functions ofAlicyclobacillus acidocaldariussqualeneâhopene cyclase
2000-02-01

The catalytic cavity of Alicyclobacillus acidocaldarius squalene-hopene cyclase is mainly lined by aromatic amino acids. In recombinant cyclases, three out of four tyrosine residues (Y) have been mutated to phenylalanine residues (F). The mutant cyclases Y495F and Y612F had less activity than the wild-type cyclase, but a wild-type product pattern. Mutant Y609F had wild-type activity but a drastically altered product pattern with hopene and significant amounts of bicyclic alpha-polypodatetraene and different tetracyclic triterpenes (dammaradienes and eupha-7,24-diene). The experiments demonstrated that Y495 and Y612 may be involved in the initiation of the cyclization reaction and Y609 in the stabilization and/or positioning of the intermediate carbocations.
Suppression of apoptosis in C3H mouse liver tumors by activated Ha-ras oncogene
2000-02-01

Liver tumors were induced in male C3H mice by a single injection of N-nitrosodiethylamine and characterized with respect to the presence of base substitutions in the hot-spot position at codon 61 of the Ha-ras proto-oncogene. An increase in Ha-ras mutation prevalence was found with time after induction of tumors, suggesting that the activated ras gene provides a selective growth advantage. However, no significant differences in 5-bromodeoxyuridine labeling indices were evident between ras mutated and ras wild-type tumors, demonstrating that cell division rates in the two tumor populations were very similar. Apoptotic indices were determined by counting eosinophilic apoptotic bodies. The frequency of occurrence of apoptotic bodies was found to be approximately five times lower in tumors with Ha-ras mutations when compared with tumors not showing the mutation. This demonstrates that the activated p21(Ras) protein has anti-apoptotic activity in transformed mouse hepatocytes in vivo and suggests that the preferential outgrowth of Ha-ras-mutated hepatoma cells is mediated by suppression of apoptosis rather than by stimulation of cell division.
Neo-osseous Flaps Using Demineralized Allogeneic Bone in a Rat Model
2000-02-01

Surgical reconstruction with revascularized bone grafts can be compromised by donor tissue limitations and may be refined by prefabrication of compound neoflaps using bone substitutes. The principal suitability of demineralized allogeneic bone (DALB) slabs in fabricating neo-osseous flaps based on the inferior epigastric vascular system was studied and compared with neoflaps with autologous bone (AUB). In 45 rats, the histological pattern of bone formation in response to angiogenesis induced by vessel implantation was assessed, and characteristics of vascularization of the neoflap were studied microangiographically at 2, 4, 6, and 8 weeks. Histological techniques included decalcified and nondecalcified sections, as well as intravital polyfluorochrome labeling. Blood flow of the neoflap was also assessed quantitatively using 15-microm microspheres labeled with technetium 99-methylene diphosphate (99-MDP) 8 weeks after flap fabrication. Although the DALB neoflaps showed consistent bone formation and neovascularization, the bone regeneration process was delayed distinctly in comparison with AUB. Microangiographically, however, no differences between the two types of grafts became apparent during all time periods tested. Furthermore, the radioactivity of the DALB neoflap, which means bone blood flow per dry weight, was significantly higher than in AUB grafts and even more than that of intact iliac bone (p = 0.001). The exact meaning of elevated blood flow in DALB and similar degrees of vascularization corresponding to native AUB grafts remains to be determined, but may be a sign of ongoing bone formation resulting in a suitable DALB-containing neo-osseous flap in the long term. The authors findings support that allogeneic bone could be a potential substitute for AUB in creating a prefabricated neo-osseous flap.
Synthesis and Crystal Structures of ATi[Nb6Cl18] Compounds (A = K, Rb, Cs, In, Tl)
2000-02-01

Abstract New quaternary niobium cluster chlorides corresponding to the general formula ATi[Nb 6 Cl 18 ] (A = K, Rb, Cs, In, Tl) have been synthesized in sealed quartz tubes at 720 °C, starting from stoichiometric amounts of NbCl 5 , niobium metal, TiCl 3 , and ACl (A = K, Rb, Cs), or In or Tl metals. The structures of RbTi[Nb 6 Cl 18 ] and CsTi[Nb 6 Cl 18 ] were determined using single crystal X-ray diffraction. RbTi[Nb 6 Cl 18 ] crystallizes in the rhombohedral crystal system, space group R3̄ (no. 148), Z = 3, with lattice parameters: a = 9.163(4), c = 25.014(14) Å (hexagonal setting). The structure refinement converged to R 1 = 0.044 and wR 2 = 0.058 for all data. In this structure, discrete [Nb 6 Cl 18 ] 4- cluster units are linked by Rb + and Ti 3+ cations, located in a 12-coordinated anticubeoctahedral and octahedral chloride coordination environment, respectively. In contrast, CsTi[Nb 6 Cl 18 ] crystallizes in the trigonal crystal system, space group P3̄1c (no. 163), Z = 2. The lattice parameters were determined to be a = 9.1075(6), c = 17.0017(8) Å. The structure refinement gives the reliability factors R 1 = 0.029 and wR 2 = 0.063 for all data. The structure is built up of discrete octahedral [Nb 6 Cl 18 ] 4- cluster units, linked by Cs + and Ti 3+ cations which are located in a distorted hexagonal antiprismatic and octahedral chloride coordination environment, respectively. The structures of the compounds ATi[Nb 6 Cl 18 ] (A = K, In, Tl) were found to be isotypic with RbTi[Nb 6 Cl 18 ], and their unit cell parameters were refined using X-ray powder diffraction analysis.