Showing papers by "University of Marburg published in 1992"

The skeletal muscle chloride channel in dominant and recessive human myotonia.

Abstract: Autosomal recessive generalized myotonia (Becker's disease) (GM) and autosomal dominant myotonia congenita (Thomsen's disease) (MC) are characterized by skeletal muscle stiffness that is a result of muscle membrane hyperexcitability. For both diseases, alterations in muscle chloride or sodium currents or both have been observed. A complementary DNA for a human skeletal muscle chloride channel (CLC-1) was cloned, physically localized on chromosome 7, and linked to the T cell receptor beta (TCRB) locus. Tight linkage of these two loci to GM and MC was found in German families. An unusual restriction site in the CLC-1 locus in two GM families identified a mutation associated with that disease, a phenylalanine-to-cysteine substitution in putative transmembrane domain D8. This suggests that different mutations in CLC-1 may cause dominant or recessive myotonia.

Influenza virus hemagglutinin with multibasic cleavage site is activated by furin, a subtilisin-like endoprotease.

Abstract: Many viruses have membrane glycoproteins that are activated at cleavage sites containing multiple arginine and lysine residues by cellular proteases so far not identified. The proteases responsible for cleavage of the hemagglutinin of fowl plague virus, a prototype of these glycoproteins, has now been isolated from Madin-Darby bovine kidney cells. The enzyme has a mol. wt of 85,000, a pH optimum ranging from 6.5 to 7.5, is calcium dependent and recognizes the consensus sequence R-X-K/R-R at the cleavage site of the hemagglutinin. Using a specific antiserum it has been identified as furin, a subtilisin-like eukaryotic protease. The fowl plague virus hemagglutinin was also cleaved after coexpression with human furin from cDNA by vaccinia virus vectors. Peptidyl chloroalkylketones containing the R-X-K/R-R motif specifically bind to the catalytic site of furin and are therefore potent inhibitors of hemagglutinin cleavage and fusion activity.

Glucagon-like peptide-1 cells in the gastrointestinal tract and pancreas of rat, pig and man.

Abstract: A highly specific monoclonal antibody directed against the C-terminal part of glucagon-like peptide-1 (GLP-1) was raised to immunohistochemically evaluate the distribution of GLP-1 containing cells in the entire gastrointestinal tract including pancreas of rat, pig and man. In the pancreas GLP-1-immunoreactive cells were found variously shaped and predominantly located in the periphery of the islets. Ultrastructurally, GLP-1 was co-localized with glucagon in the alpha-granula of A-cells and was mainly restricted to the electrondense core. In the intestine open type cells reaching the lumen via a slender apical process were stained with the GLP-1 antibody. They occurred in all parts of the crypts but predominantly in the basal portion. The density of GLP-1 immunoreactive cells varied between species in a characteristic order: rat greater than pig greater than man. In pig and human gut a large number of cells occurred in the distal jejunum and ileum. A continuous increase of cell densities was found from the proximal to the distal colon resulting in highest numbers in the rectum. In rats the highest cell density occurred in the ileum. Again, a continuous increase of GLP-1-positive cell numbers was evident from the proximal to the distal portion of small and large bowel. GLP-1 was partly co-localized with PYY. The GLP-1 positive cells appeared electronmicroscopically as L-cells with the typical large granula. This morphological data indicates that GLP-1-releasing cells in the small intestine are appropriately positioned in the distal part to sense and respond to the presence of nutrients that have escaped the absorptive surface of the upper small intestine.

Cloning by recognition site screening of two novel GT box binding proteins: a family of Sp1 related genes

Abstract: Previous analyses of the uteroglobin gene promoter revealed a GT1 box which is also found in the SV40 enhancer. The GT1 element in the context of the uteroglobin promoter is active in Ishikawa cells, a human endometrial cell line, but not in HeLa cells. Here we report the cloning by recognition site screening of two factors (SPR-1 and SPR-2) which bind to this GT1 motif. SPR-1 and SPR-2 are homologues of the transcription factor Sp1. All three proteins are closely related members of a gene family encoding proteins with very similar structural features. Like Sp1, SPR-1 and SPR-2 contain glutamine and serine/threonine rich amino acid stretches. Most significantly, the DNA binding domains of all three proteins are highly conserved and they recognize GT as well as GC boxes identically. SPR-2 mRNA is expressed ubiquitously, whereas SPR-1 transcripts are abundant in the brain but barely detectable in other organs. The possible function of these factors for the activity of the uteroglobin promoter is discussed.

Optical investigation of Bloch oscillations in a semiconductor superlattice.

Abstract: We report the study of optical dephazing of Wannier-Stark ladder excitations in a semiconductor superlattice by means of transient degenerate four-wave mixing. We observe pronounced modulations of the signal with a time period varying linearly with the electric field. The time period is found to equal the temporal periodicity of Bloch oscillations, in agreement with theory. In addition, we find that the dephazing time decreases with increasing localization of the Wannier-Stark states, which is attributed to carrier escape out of the lowest miniband.

Role of octreotide in the prevention of postoperative complications following pancreatic resection.

Abstract: Though morbidity and mortality rates following pancreatic resection have improved in recent years, they are still around 35% and 5%, respectively. Typical complications, such as pancreatic fistula, abscess, and subsequent sepsis, are chiefly associated with exocrine pancreatic secretion. In order to clarify whether the perioperative inhibition of exocrine pancreatic secretion prevents complications, we assessed the efficacy of octreotide, a long-acting somatostatin analogue. We conducted a randomized, double-blind, placebo-controlled, multicenter trial in 246 patients undergoing major elective pancreatic surgery. Patients were stratified into a high-risk stratum (limited to patients with pancreatic and periampullary tumors) or low-risk stratum (patients with chronic pancreatitis). Patients received octreotide (3 x 100 micrograms) or placebo subcutaneously for 7 days perioperatively. Eleven complications were defined: death, leakage of anastomosis, pancreatic fistula, abscess, fluid collection, shock, sepsis, bleeding, pulmonary insufficiency, renal insufficiency, and postoperative pancreatitis. Two hundred patients underwent pancreatic head resection, 31 patients underwent left resection, and 15 patients had other procedures. The overall mortality rate within 90 days was 4.5%, with 3.2% in the octreotide group and 5.8% in the placebo group. The complication rate was 32% in the patients receiving octreotide (40 of 125 patients) and 55% in patients receiving placebo (67 of 121 patients) (p less than 0.005). In the patients in the high-risk stratum, complications were observed in 26 of the 68 (38%) patients treated with octreotide and in 46 of 71 (65%) patients given placebo (p less than 0.01). Whereas in patients in the low-risk stratum, the complication rate was 25% (14 of 57 patients) in those treated with octreotide and 42% (21 of 50 patients) in patients given placebo (p = NS). The perioperative application of octreotide reduces the occurrence of typical postoperative complications after pancreatic resection, particularly in patients with tumors.

Coherent submillimeter-wave emission from charge oscillations in a double-well potential.

Abstract: We directly observe the electromagnetic radiation emitted by electrons coherently oscillating between the two wells of a semiconductor coupled-quantum-well structure. Using time-resolved coherent detection of the submillimeter-wave radiation from these spatial charge oscillations, we trace up to fourteen oscillations at 1.5 THz before phase relaxation destroys the coherence of the oscillating wave packet. In addition to the oscillatory electromagnetic signal, we also observe an instantaneous signal from electric-field-induced optical rectification in the semiconductor structure.

Body temperature and metabolic rate during natural hypothermia in endotherms.

Abstract: During daily torpor and hibernation metabolic rate is reduced to a fraction of the euthermic metabolic rate. This reduction is commonly explained by temperature effects on biochemical reactions, as described by Q10 effects or Arrhenius plots. This study shows that the degree of metabolic suppression during hypothermia can alternatively be explained by active downregulation of metabolic rate and thermoregulatory control of heat production. Heat regulation is fully adequate to predict changes in metabolic rate, and Q10 effects are not required to explain the reduction of energy requirements during hibernation and torpor.

Characterization of cspB, a Bacillus subtilis inducible cold shock gene affecting cell viability at low temperatures.

Abstract: A new class of cold shock-induced proteins that may be involved in an adaptive process required for cell viability at low temperatures or may function as antifreeze proteins in Escherichia coli and Saccharomyces cerevisiae has been identified. We purified a small Bacillus subtilis cold shock protein (CspB) and determined its amino-terminal sequence. By using mixed degenerate oligonucleotides, the corresponding gene (cspB) was cloned on two overlapping fragments of 5 and 6 kb. The gene encodes an acidic 67-amino-acid protein (pI 4.31) with a predicted molecular mass of 7,365 Da. Nucleotide and deduced amino acid sequence comparisons revealed 61% identity to the major cold shock protein of E. coli and 43% identity to a family of eukaryotic DNA binding proteins. Northern RNA blot and primer extension studies indicated the presence of one cspB transcript that was initiated 119 bp upstream of the initiation codon and was found to be induced severalfold when exponentially growing B. subtilis cell cultures were transferred from 37 degrees C to 10 degrees C. Consistent with this cold shock induction of cspB mRNA, a six- to eightfold induction of a cspB-directed beta-galactosidase synthesis was observed upon downshift in temperature. To investigate the function of CspB, we inactivated the cold shock protein by replacing the cspB gene in the B. subtilis chromosome with a cat-interrupted copy (cspB::cat) by marker replacement recombination. The viability of cells of this mutant strain, GW1, at freezing temperatures was strongly affected. However, the effect of having no CspB in GW1 could be slightly compensated for when cells were preincubated at 10 degrees C before freezing. These results indicate that CspB belongs to a new type of stress-inducible proteins that might be able to protect B. subtilis cells from damage caused by ice crystal formation during freezing.

Four homologous domains in the primary structure of GrsB are related to domains in a superfamily of adenylate-forming enzymes.

Abstract: The entire nucleotide sequence of the Bacillus brevis grsB gene encoding the gramicidin S synthetase 2, which activates and condenses the four amino acids proline, valine, ornithine and leucine has been determined. The gene contains an open reading frame of 13,359 bp which encodes a protein of 4453 amino acids with a predicted Mr of 510,287. The gene is located within the gramicidin S biosynthetic operon, also containing the genes grsT and grsA, whose nucleotide sequences have been determined previously. Within the GrsB amino acid sequence four conserved and repeated domains of about 600 amino acids (45-50% identity) have been identified. The four domains are separated by non-homologous sequences of about 500 amino acids. The domains also share a high degree of similarity (20-70%) with eight peptide synthetases of bacterial and fungal origin as well as with conserved sequences of nine other adenylate-forming enzymes of diverse origin. On the basis of sequence homology and functional similarities, we infer that those enzymes share a common evolutionary origin and present a phylogenetic tree for this superfamily of domain-bearing enzymes.

Origin and consequences of the compensation (Meyer-Neldel) law.

Abstract: We have recently demonstrated that the Meyer-Neldel (MN) rule (compensation law) may be understood as arising naturally when the activation energy for a process is significantly larger than both the typical excitations available and kT. This conclusion was supported by the results of two microscopic models, related to special cases. In the present paper we present arguments, based on general results from statistical physics, which lead to the same conclusion. We show that this simple explanation also leads to the solution of a number of puzzles which have been associated with Meyer-Neldel behavior. We show that phenomena in groups of similar materials yield similar MN slopes. Finally, we show that the values of the slope for semiconductors with gaps in the 1--2-eV range are consistent with the suggestion that optical phonons are the source of the excitation energy in such processes.

Activation of rat liver perisinusoidal lipocytes by transforming growth factors derived from myofibroblastlike cells. A potential mechanism of self perpetuation in liver fibrogenesis.

Abstract: Rat liver perisinusoidal lipocytes (PL) cultured on uncoated plastic transform spontaneously within 6-10 d to myofibroblastlike cells (MFBlC) Parallel to the transformation the TGF alpha- and TGF beta 1-mRNA expression increased and was highest in MFBlC Competitive radioligand binding assays demonstrated that in contrast to untransformed PL the MFBlC synthesize and secrete transforming growth factor (TGF)-alpha (15 fmol/cell per 24 h) and predominantly the latent form of TGF beta 1 (02 fmol/cell per 24 h) Medium conditioned by MFBlC (MFBcM) significantly stimulated PL proliferation with little effect on PL proteoglycan synthesis By transient acidification of the MFBcM, known to activate the latent form of TGF beta 1, the stimulatory effect on PL proteoglycan synthesis was enhanced and furthermore PL transformation (measured by expression of iso-alpha smooth muscle actin and loss of retinylpalmitate) was accelerated Preincubation of this medium with neutralizing antibodies to TGF beta resulted in (a) the growth inhibitory effect was converted to a growth stimulation and (b) the stimulatory effect on proteoglycan synthesis was abolished In summary our data indicate that progressive activation of PL on plastic (transformation to MFBlC) leads to an enhanced expression of the TGF alpha- and TGF beta 1-mRNAs and secretion of the corresponding proteins Medium conditioned by MFBIC stimulates proliferation, transformation, and PG synthesis of untransformed PL These mechanisms are suggested to be relevant in self perpetuation of liver fibrogenesis

Mitochondrial myopathy of childhood associated with depletion of mitochondrial DNA

Abstract: We have studied five children with mitochondrial myopathy manifesting within or soon after the first year of life. Muscle biopsies showed ragged-red fibers and decreased respiratory chain activity. All five patients had a severe decrease (2 to 34% of normal) in the amount of muscle mitochondrial DNA (mtDNA). The depletion of mtDNA correlated with absence of mtDNA-encoded translation products and with loss of cytochrome c oxidase enzyme activity in individual muscle fibers. This mitochondrial myopathy of childhood illustrates one phenotypic expression of a novel pathogenetic mechanism in mitochondrial diseases, the specific depletion of mtDNA in affected tissues.

Intensity instabilities of semiconductor lasers under current modulation, external light injection, and delayed feedback

Abstract: We investigate the occurrence of instabilities related to possible transitions to chaos in specific configurations based on semiconductor lasers. Various scenarios, such as period doubling, frequency locking, quasiperiodicity, and intermittency, are observed experimentally as functions of the control parameters. These are, respectively, the current modulation, external light injection, and delayed feedback. The experimental findings are described and discussed on the basis of semiconductor-laser rate equations.

Spatial and temporal coherence in cortico-cortical connections: A cross-correlation study in areas 17 and 18 in the cat

Abstract: Visual cortical areas are richly but selectively connected by "patchy" projections. We characterized these connections physiologically with cross-correlograms (CCHs), calculated for neuron pairs or small groups located one each in visual areas 17 and 18 of the cat. The CCHs were then compared to the visuotopic and orientation match of the neurons' receptive fields (RFs). For both spontaneous and visually driven activity, most non-flat correlograms were centered; i.e. the most likely temporal relationship between spikes in the two areas is a synchronous one. Although spikes are most likely to occur simultaneously, area 17 spikes may occur before area 18 or vice versa, giving the cross-correlogram peak a finite width (temporal dispersion). Cross-correlograms fell into one of three groups according to their full-width at half peak height: 1-8 ms (modal width, 3 ms), 15-65 ms (modal width 30 ms), or 100-1000 ms (modal width 400 ms). These classificatory groups are nonoverlapping; the three types of coupling appeared singly and in combination. Neurons whose receptive fields (RFs) are nonoverlapping or cross-oriented may yet be coupled, but the coupling is more likely to be the broadest type of coupling than the medium-dispersed type. The sharpest type of coupling is found exclusively between neurons with at least partially overlapping RFs and mostly between neurons whose stimulus orientation preferences matched to within 22.5 deg. The maximum spatial dispersion observed in the RFs of coupled neurons compares well with the maximum divergence seen anatomically in the A18/A17 projection system. We suggest three different mechanisms to produce each of the three different degrees of observed spatial and temporal coherence. All mechanisms use common input of cortical origin. For medium and broad coupling, this common input arises from cell assemblies split between both sides of the 17/18 projection system, but acting synchronously. Such distributed common-input cell assemblies are a means of overcoming sparse connectivity and achieving synaptic transmission in the pyramidal network.

H2-forming methylenetetrahydromethanopterin dehydrogenase, a novel type of hydrogenase without iron-sulfur clusters in methanogenic archaea

Abstract: A novel hydrogenase has recently been found in methanogenic archaea. It catalyzes the reversible dehydrogenation of methylenetetrahydromethanopterin (CH2 = H4MPT) to methenyltetrahydromethanopterin (CH identical to H4MPT+) and H2 and was therefore named H2-forming methylenetetrahydromethanopterin dehydrogenase. The hydrogenase, which is composed of only one polypeptide with an apparent molecular mass of 43 kDa, does not mediate the reduction of viologen dyes with either H2 or CH2 = H4MPT. We report here that the purified enzyme from Methanobacterium thermoautotrophicum exhibits the following other unique properties: (a) the colorless protein with a specific activity of 2000 U/mg (Vmax) did not contain iron-sulfur clusters, nickel, or flavins; (b) the activity was not inhibited by carbon monoxide, acetylene, nitrite, cyanide, or azide; (c) the enzyme did not catalyze an isotopic exchange between 3H2 and 1H+; (d) the enzyme catalyzed the reduction of CH identical to H4MPT+ with 3H2 generating [methylene-3H]CH2 = H4MPT; and (e) the primary structure contained at most four conserved cysteines as revealed by a comparison of the DNA-deduced amino acid sequence of the proteins from M. thermoautotrophicum and Methanopyrus kandleri. None of the four cysteines were closely spaced as would be indicative for a (NiFe) hydrogenase or a ferredoxin-type iron-sulfur protein. Properties of the H2-forming methylenetetrahydromethanopterin dehydrogenase from Methanobacterium wolfei are also described indicating that the enzyme from this methanogenic archaeon is very similar to the enzyme from M. thermoautotrophicum with respect both to molecular and catalytic properties.

Stark effect of one-dimensional Wannier excitons in polydiacetylene single crystals.

Abstract: Electric-field-modulated reflectivity of three different polydiacetylenes---PTS, poly[2,4-hexadiyne-1,6-diol-bis(p-toluene sulfonate)]; PFBS, poly[2,4-hexadiyne-1,6-diol-bis(p-fluorobenzene sulfonate)]; and DCHD, poly[1,6-di(n-carbazolyl)-2,4-hexadiyne]---has been measured and is analyzed with respect to the underlying mechanism for the observed sensitivity of \ensuremath{\pi}-${\mathrm{\ensuremath{\pi}}}^{\mathrm{*}}$ transitions to electric fields. Excitons of high oscillator strength and their vibronic satellites respond to fields along the polymer backbone by a large quadratic Stark shift, revealing a large polarizability for this direction. About 0.5 eV above the excitonic absorption edge, in a region of relatively low absorption, electroreflectance signals of different origin are observed, which, contrary to the excitonic signals, vary strongly in size among different specimens of the same composition. Line-shape analysis and its dependence on the field strength identify this signal as the Franz-Keldysh effect of free-electron states, the continuum of the excitons, and exclude an assignment to forbidden exciton transitions. The large polarizability of the excitonic states, which results from unusually strong coupling to their continuum, is consistent with a Wannier exciton extending over about ten conjugated bonds and with a small reduced mass of the order 0.1${\mathit{m}}_{0}$. The large binding energy (0.5 eV) and oscillator strength (f\ensuremath{\approxeq}0.6) of the excitons and their extremely strong coupling to continuum states are attributed to the one-dimensional character of the electron states.

Sonography in acute colonic diverticulitis. A prospective study.

Abstract: The clinical value of high-resolution real-time sonography for the diagnosis of acute and complicated colonic diverticulitis was prospectively studied in 130 consecutive patients with abdominal complaints, because of which the disease entered into differential consideration. The results of ultrasound investigation were compared with those of clinical examination on admission. Regarding history and initial clinical evaluation, diverticulitis was graded as “highly suspected” in 19 (36.5 percent) out of a total of 52 patients with later proven colonic diverticulitis (prevalence 40 percent), as “possible but equivocal” in 24 (46.2 percent), and as “very unlikely” in the remaining nine (17.3 percent) patients. Ultrasonography enabled the diagnosis of diverticulitis with an overall accuracy of 97.7 percent, a sensitivity of 98.1 percent, and a specificity of 97.5 percent. The predictive values of positive and negative ultrasound examinations were 96.2 percent and 98.5 percent, respectively. The echomorphologic features of acute diverticulitis include visualization of a colon segment presenting with local tenderness on gradual compression, which showed hypoechogenic thickening of the wall and a targetlike appearance in transverse view due to inflammatory changes and muscular thickening. Sonographic signs of peridiverticulitis (hyperechoic halo) were found in 96 percent of patients, echogenic diverticula in 86 percent. Twelve (92 percent) of 13 abdominal abscesses were detected on initial ultrasound examination and could be treated by percutaneous drainage in seven cases, while six required surgical intervention. These results indicate that high-resolution sonography with graded compression is highly sensitive and specific for the imaging diagnoses of acute colonic diverticulitis and complicating abscess.

Establishment and characterisation of two cell lines with different grade of differentiation derived from one primary human pancreatic adenocarcinoma.

Abstract: From a liver metastasis of a human pancreatic adenocarcinoma, we have established cell lines for studying the cell biology of this tumor. We obtained two cell lines with different morphological, chromosomal and functional properties. One of them, named PaTu 8988s, revealed a solid growth in nude mouse xenografts with cells exhibiting only occasional polar organisation of the cytoplasm. In general, no apical or basolateral plasma membrane domains could be distinguished and the sparse organelles were randomly distributed throughout the cytoplasm. Secretory products, such as mucin, were weakly stained histochemically or were completely absent. Transglutaminase (TGase) activity used as a marker for cellular differentiation was low in these cells. The other cell line, named PaTu 8988t, grew tumors composed of tubular structures when injected subcutaneously into nude mice. Cells were polarized with distinct apical and basolateral plasma membranes and the cytoplasmatic organelles were arranged with the nucleus in the lower part of the cell, while the apical cytoplasm contained the Golgi complex and numerous secretion granules. A high content of mucin was stained histochemically and transglutaminase activity was ten times higher than in PaTu 8988s. Comparing the chromosome number per metaphase plate, both cell lines showed a major peak, with 45-55 chromosomes per metaphase plate in PaTu 8988s and about 110-120 chromosomes per metaphase plate in PaTu 8988t. When the two cell lines were injected intravenously into the tail vein of nude mice, only PaTu 8988s developed metastases localized exclusively in the lung, whereas PaTu 8988t produced no metastases in any organ. We conclude, that two cell lines exhibiting different grades of differentiation as well as a different potency to metastasize can be established from the same primary tumor, and that these cell lines represent a suitable model for further study of the cell biology of human pancreatic adenocarcinoma.

Apparent lack of N-glycosylation in the asexual intraerythrocytic stage of Plasmodium falciparum.

Abstract: This study investigates protein glycosylation in the asexual intraerythrocytic stage of the malaria parasite, Plasmodium falciparum, and the presence in the infected erythrocyte of the respective precursors. In in vitro cultures, P. falciparum can be metabolically labeled with radioactive sugars, and its multiplication can be affected by glycosylation inhibitors, suggesting the capability of the parasite to perform protein-glycosylation reactions. Gel-filtration analysis of sugar-labeled malarial proteins before and after specific cleavage of N-glycans or O-glycans, respectively, revealed the majority of the protein-bound sugar label to be incorporated into O-glycans, but only little (7–12% of the glucosamine label) or no N-glycans were found. Analysis of the nucleotide sugar and sugar-phosphate fraction showed that radioactive galactose, glucosamine, fucose and ethanolamine were converted to their activated derivatives required for incorporation into protein. Mannose was mainly recovered as a bisphosphate, whereas the level of radiolabeled GDP-mannose was below the detection limit. The analysis of organic-solvent extracts of sugar-labeled cultures showed no evidence for the formation by the parasite of dolichol cycle intermediates, the dedicated precursors in protein N-glycosylation. Consistently, the amount of UDP-N-acetylglucosamine formed did not seem to be affected by the presence of tunicamycin in the culture. Oligosaccharyl-transferase activity was not detectable in a lysate of P. falciparum, using exogenous glycosyl donors and acceptors. Our studies show that O-glycosylation is the major form of protein glycosylation in intraerythrocytic P. falciparum, whereas there is little or no protein N-glycosylation. A part of these studies has been published in abstract form [Dieckmann-Schuppert, A., Hensel, J. and Schwarz, R. T. (1991) Biol. Chem. Hoppe-Seyler 372, 645].

Hormone-Induced Pancreatitis

Abstract: Intravenous infusion of the synthetic cholecystokinin analogue cerulein at a dose of 0.25 micrograms/kg/h causes maximal stimulation of pancreatic exocrine secretion. The infusion of supramaximal doses of cerulein (5 and 10 micrograms/kg/h) induces a significant increase in pancreatic enzymes in blood, and interstitial edema and inflammatory cell infiltration. This model of hormone-induced pancreatitis works in rats, mice, dogs and hamsters. Besides intravenous infusion, repeated intraperitoneal injections can also be used for induction of pancreatitis. In the early phase of cerulein-induced pancreatitis, large autophagic vacuoles result from fusion of zymogen granules within the acinar cell. This is accompanied by an increase in lysosomal enzyme activity and activation of trypsinogen which finally leads to cellular necrosis. All animals survive the induction of pancreatitis. The pancreas completely regenerates within 6 days after induction of pancreatitis. This model of experimental pancreatitis favors the analysis of intracellular events in the early phase of pancreatitis.

Bovine coronavirus uses N-acetyl-9-O-acetylneuraminic acid as a receptor determinant to initiate the infection of cultured cells.

Abstract: The importance of N-acetyl-9-O-acetylneuraminic acid (Neu5,9Ac2) as a receptor determinant for bovine coronavirus (BCV) on cultured cells was analysed. Pretreatment of MDCK I (Madin Darby canine kidney) cells with neuraminidase or acetylesterase rendered the cells resistant to infection by BCV. The receptors on a human (CaCo-2) and a porcine (LLC-PK1) epithelial cell line were also found to be sensitive to neuraminidase treatment. The susceptibility to infection by BCV was restored after resialylation of asialo-MDCK I cells with Neu5,9Ac2. Transfer of sialic acid lacking a 9-O-acetyl group was ineffective in this respect. These results demonstrate that 9-O-acetylated sialic acid is used as a receptor determinant by BCV to infect cultured cells. The possibility is discussed that the initiation of a BCV infection involves the recognition of different types of receptors, a first receptor for primary attachment and a second receptor to mediate the fusion between the viral envelope and the cellular membrane.

Progressive loss of cytochrome c oxidase in the human extraocular muscles in ageing — a cytochemical-immunohistochemical study

Abstract: Cytochrome c oxidase (complex IV of the respiratory chain) was studied histochemically in autoptic human extraocular muscles (n = 135), reaveling randomly distributed single fibers without enzyme activity. The enzyme defect was expressed in all the mitochondria of an involved fiber as evidenced by ultracytochemistry. Succinate dehydrogenase showed normal histochemical reactivity. The defects occured already in the second decade and were regularly seen from the third decade on. The defect density (defects/mm2)increased from approx. 1/mm2 below The fifth decade to about 4/mm2 in advanced age (P = 0.000). The highest defect density was observed in the levator palpebrae muscle. On the whole, the defect density was about 5–6 times higher in the extraocular muscles than in the limb muscle, diaphragm and heart (Muller-Hocker, 1989, 1990). Immunocytochemical detection of cytochrome c oxidase showed that loss of cytochrome c oxidase activity was due to an almost complete absence of both nuclear and mitochondria subunits of the enzyme. The results document different organ and heterogeneic cellular sensitivity to the age-related loss of cytochrome c oxidase. The loss of both mitochondrial and nuclear subunits indicates that nuclear factors are most probably involved in the decline of the respiratory chain function in senescence.