Showing papers by "University of Zurich published in 1987"

Primary sensory neurons of the rat showing calcitonin gene-related peptide immunoreactivity and their relation to substance P-, somatostatin-, galanin-, vasoactive intestinal polypeptide- and cholecystokinin-immunoreactive ganglion cells.

Abstract: By use of the indirect immunofluorescence technique the distribution of calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) has been analyzed in cervical and lumbar dorsal root ganglia of untreated and colchicine-treated rats. In addition, lumbar ganglia were examined 2 weeks after transection of the sciatic nerve. The occurrence of CGRP-positive cells in relation to ganglion cells containing substance P-, somatostatin-, galanin-, cholecystokinin (CCK)-, and vasoactive intestinal polypeptide (VIP)/peptide histidine isoleucin (PHI)-LI has been evaluated on consecutive sections as well as using elution-restaining and double-staining techniques.

Antigen presentation and tumor cytotoxicity by interferon-γ-treated microglial cells

Abstract: In this study microglial cells isolated from brain cell cultures of newborn mice were characterized and investigated for morphology, their responses to growth factors and their functional properties. The microglial cells were phagocytic, contained nonspecific esterase activity and expressed Fc (IgG1/2b) and type-3 complement receptors. Scanning electron microscopy revealed that in analogy to brain tissue two types of microglial cells are present in the cultures: the ameboid and the ramified type which both display similar appearance by transmission electron microscopy. Interleukin 3 and the granulocyte-macrophage colony-stimulating factor were potent growth factors for the cultured microglial cells. The cells were negative for class II antigens (Ia) of the major histocompatibility antigen complex. However, upon treatment with interferon-γ (IFN-γ) microglial cells became Ia+ and functioned as antigen-presenting cells when tested on ovalbumin-specific Ia-restricted helper T cells. Furthermore, microglial cells exposed to IFN-γ and endotoxin developed tumor cell cytotoxicity and produced tumor necrosis factor α. Taken together, microglial cells share the characteristics of cells of the macrophage lineage.

Chemistry and biochemistry of metallothionein.

Abstract: A wealth of chemical, spectroscopic and structural data attest to the uniqueness of the metallothioneins as a group of novel bioinorganic structures. Their earmarking feature is the arrangement of “soft” metal ions in complexes with cysteine side chains to form discrete metal-thiolate clusters. In this review an account is given of the chemical characteristics of the 52 metallothioneins whose primary structures are now known completely or in part. Also included is an up-to-date summary of the spectroscopic properties and of the spatial structure models derived from X-ray diffraction crystallographic analysis and from two-dimensional nuclear magnetic resonance spectroscopy.

Comparative study with enoxacin and netilmicin in a pharmacodynamic model to determine importance of ratio of antibiotic peak concentration to MIC for bactericidal activity and emergence of resistance.

Abstract: An in vitro pharmacokinetic model was used to study the comparative antibacterial activities of multiple-dose regimens of enoxacin and netilmicin. Strains of Pseudomonas aeruginosa, Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus were exposed to changing drug concentrations, mimicking human two-compartment pharmacokinetics. Oral administration was simulated for the quinolone, and intravenous administration was simulated for the aminoglycoside. Similar ratios of peak concentration to MIC resulted in similar changes in bacterial concentrations over time with both compounds. Following the initial dose, a rapid bactericidal effect occurred, with a greater than 99% reduction of the bacterial counts within 4 h at peak concentrations more than three times the MIC. However, bacterial regrowth occurred within 24 h unless the peak concentration/MIC ratio exceeded 8:1 (P less than 0.01). For the regrowing bacteria, MICs were four- to eightfold higher, and little or no bactericidal effect occurred following the second and subsequent doses. These data demonstrate the equally potent bactericidal activity of orally administered enoxacin and intravenously administered netilmicin. Selection of resistant subpopulations was similar with each drug. The peak concentration/MIC ratio may be an important parameter in the clinical use of quinolone and aminoglycoside antibiotics.

Health Problems After Travel to Developing Countries

Abstract: Travelers to developing countries participated in a follow-up study of the health risks associated with short (less than three months) visits to these nations. Travelers to the Greek or Canary Islands served as a control cohort. Participants completed a questionnaire to elicit information regarding pretravel vaccinations, malaria prophylaxis, and health problems during and after their journey. Relevant infections were confirmed by the respondent's personal physician. The questionnaire was completed by 10,524 travelers; the answer rate was 73.8%. After a visit to developing countries, 15% of the travelers reported health problems, 8% consulted a doctor, and 3% were unable to work for an average of 15 days. The incidence of infection per month abroad was as follows: giardiasis, 7/1,000; amebiasis, 4/1,000; hepatitis, 4/1,000; gonorrhea, 3/1,000; and malaria, helminthiases, or syphilis, less than 1/1,000. There were no cases of typhoid fever or cholera.

Effect of grain boundaries on the Raman spectra, optical absorption, and elastic light scattering in nanometer-sized crystalline silicon

Abstract: The intensity of the Raman-active ${\ensuremath{\Gamma}}_{25\mathcal{'}}$ mode of nanometer-sized crystalline silicon, nc-Si, normalized to that of calcium fluoride, ${\mathrm{CaF}}_{2}$, at 322 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ was measured for samples deposited under controllably varied conditions. Changes of the intensity by a factor of up to approximately 6.7 were found. These are correlated with the lattice expansion and with the compressive stress in thin films of the material. It is suggested that the enhancement of the scattering cross section, which scales with the observed optical-absorption coefficient and diffuse elastic light scattering, is due to enhanced coupling of the electromagnetic field of the incident light to the charge-density fluctuations at the grain boundaries of the quasi-isolated crystallites.

Linear stability of Schwarzschild under perturbations which are non-vanishing on the bifurcation 2-sphere

Abstract: The authors prove boundedness on an exterior Schwarzschild wedge for Cinfinity solutions of the covariant Klein-Gordon equation which have compact support on Cauchy surfaces in Kruskal spacetime. Previously used methods enable such boundedness to be proven only for solutions whose initial data satisfy the additional restriction of vanishing at the bifurcation 2-sphere of the horizon. By employing a rarely considered discrete isometry of Kruskal spacetime and the causal propagation property of the equation, they remove this restriction. This also enables them to prove boundedness exterior to the horizon of a spacetime representing the collapse to a black hole of a spherically symmetric compact star for solutions of the same equation having Cinfinity initial data on a Cauchy surface drawn prior to the collapse.

Somatostatin immunoreactive neurons in the human hippocampus and cortex shown by immunogold/silver intensification on vibratome sections: Coexistence with neuropeptide Y neurons, and effects alzheimer‐type dementia

Abstract: The distribution of somatostatinlike immunoreactivity was studied in the hippocampal formation, retrohippocampal region, and temporal cortex in the human brain. Tissues from surgical biopsy and postmortem cases were used, and the immunogold/silver method on vibratome sections was introduced for routine applications in conjunction with primary antisera that recognise somatostatin-14 or somatostatin-28. Somatostatin-28 antisera readily stained numerous neurons, dendrites, and extensive axonal networks throughout the hippocampus and neighbouring cortex. Liquid phase absorption provided controls for specificity. The most prominent accumulations of Somatostatin immunoreactive neurons and axons occurred in the hilus of the area dentata, in CA1, and in the entorhinal and perirhinal cortices. Axonal plexuses occurred throughout the hippocampal subfields but were particularly dense in those regions rich in Somatostatin neurons. The distribution of Somatostatin immunoreactive neurons and fibers parallels the distribution of neuropeptide Y (NPY) neurons and fibers in the hippocampus and cerebral cortex to a remarkable extent. Double labelling experiments with antisera against neuropeptide Y and Somatostatin indicate a considerable frequency of coexistence of the two peptides in single neurons, particularly in large multipolar cortical neurons and also in the small bipolar white matter neurons. Regional variations exist in the amounts of coexistence found in the hippocampal subfields; somatostatin-NPY coexistence is particularly high in the hilus of the area dentata, the subicular complex, and the deep layers of the entorhinal and perirhinal cortices. In the hippocampi and temporal cortices in cases of Alzheimer-type dementia compared to those of age-matched control brains, there is a significant to severe loss of Somatostatin immunoreactive neurons and axons. This loss is most severe in those regions with the highest indices of neurofibrillary tangles and neuritic plaques–the hilus of the area dentata, CA1, and the entorhinal and perirhinal cortices. Surviving Somatostatin neurons are distorted with short dendrites and truncated axons. Neuritic plaques identified on double label experiments with thioflavin include Somatostatin axons but not neurons.

Mechanisms of heat-shock gene activation in higher eukaryotes

Abstract: Publisher Summary This chapter discusses the components of heat-shock gene-activation systems: the cis -acting elements and the trans -acting factors. The chapter also explains the way these components act together to result in transcription activation and the way multiple controls are achieved. It also illustrates the way a cell detects the environmental stimulus and translates it into gene activation and the way the functions of gene products relate to this process. The chapter focuses on heat-shock gene activation in higher eukaryotes and relates this to the field of higher eukaryotic transcription. Heat-shock gene induction represents a model case for gene activation in two respects. During transient heat induction, heat-shock genes undergo reprogramming from the off- to the on-state; heat-shocked and unshocked cells differ in their states of gene activation in a way analogous to two different cell types or cell lineages. Some heat-shock genes are not only transiently heat inducible but also activated during normal cell growth or development, which leads to the question of how multiple control mechanisms act on the same gene.

OVEC, a versatile system to study transcription in mammalian cells and cell-free extracts

Abstract: We have developed a vector, OVEC ("oligonucleotide vector") to study DNA sequences involved in the regulation of transcription in mammalian cells. This vector is equally suitable for studying expression in vivo after transfection into cells, or for transcription studies in vitro with cell-free extracts. Putative cis-acting DNA segments from enhancers or promoters can be inserted at a position immediately upstream of the TATA box and coding sequence of the rabbit beta-globin gene. A regulatory DNA segment can be tested by itself or in conjunction with an enhancer located either in an adjacent upstream position, or downstream of the beta-globin gene. S1 nuclease mapping can be used to study transcription from circular and linear templates and run-off transcription in vitro is also feasible. Transcripts from a reference globin gene with a small deletion around the transcription initiation site can be measured with the same S1 nuclease probe and thus serve as an internal standard. We demonstrate the usefulness of OVEC by inserting either short oligonucleotides comprising a metal responsive enhancer element, or the SV40 enhancer, directly upstream of the TATA box. Both constructs yield high levels of correctly initiated transcripts in a transient expression assay in HeLa cells. In a HeLa cell nuclear extract the SV40 enhancer stimulates transcription 40-fold.

The SV40 enhancer can be dissected into multiple segments, each with a different cell type specificity

Abstract: The SV40 enhancer is known to be active in a wide variety of tissues and species. It contains a number of sequence motifs that can be bound by protein factors and whose integrity is essential for full enhancer activity. We have individually analyzed three synthetic oligonucleotides derived from sequences present within the SV40 enhancer: two oligonucleotides contain variants of the enhancer "core" sequence (designated corePVUII and coreC) and the third represents a region containing a decanucleotide homology to the immunoglobulin promoters/enhancers {designated SPHI). The oligonucleotides were multimerized and linked to a [3-globin test gene. Transcripts of the test gene were analyzed following transient expression in 10 cell lines representing a broad spectrum of tissues. We show that each of the three short segments can individually act as an enhancer when present in multiple copies. None of these enhancers is ubiquitously active; however, each shows activity in a distinctive subpopulation of cell lines. This cell type specificity is most remarkable in the case of the two oligonucleotide segments containing the core sequences. One of these is primarily active in CV-I cells, whereas the other exhibits a cell type specificity identical to that of the entire enhancer, possibly identifying it as the most important sequence element within the native SV40 enhancer. Our data suggest that a particular cell type specificity is typical for individual enhancer segments, and that enhancers of differing specificity can be assembled from the individual sequence motifs by combining them in different patterns.

Ontogeny of the calcium binding protein calbindin D-28k in the rat nervous system.

Abstract: Calbindin D-28k immunoreactivity appeared at embryonal day 14 (E14) in the central nervous system as well as in the sensory organs and at E15 in the peripheral nervous system of the rat. At E14 the infundibular process of the diencephalon, cells of the posterior hypothalamus and of the dorsal thalamus were the only structures strongly immunostained in the brain, whereas neurons of the basal plate of the spinal cord, medulla oblongata and of the out-ermost layer of the cerebral cortex were only faintly labeled. Calbindin positive cerebellar Purkinje cells could be discerned at E15 together with a few cells in the hippocampus and in ganglia of the cranial nerves. At E19 various mesencephalic and metencephalic structures, spinal ganglion cells and basal ganglia displayed calbindin immunoreactive cells. The adult pattern of calbindin immunoreactivity (Garcia Segura et al. 1984) was reached before birth in most brain regions. In general, cells which displayed calbindin during brain development were also calbindin positive in the adult animal. Exceptions to this rule were cells of the deep nuclei of the cerebellum and non-neuronal cells which transiently expressed calbindin during development. Calbindin appeared in a given brain region almost invariably 1 or 2 days after the cessation of cell division and the beginning of neuronal migration and extension of neuronal processes. The calcium binding protein calbindin might influence these Ca2+-dependent processes.

Sensory vagal innervation of the rat esophagus and cardia: a light and electron microscopic anterograde tracing study.

Abstract: Wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) was injected into nodose ganglia of rats. In the esophagus and cardia, dense networks of anterogradely labeled fibers and beaded terminal-like arborisations were observed around myenteric ganglia after combined histochemistry for HRP and acetylcholinesterase. The muscularis externa and interna proper were free of label except for a few traversing fibers. Submucosal and mucosal labeling was rather sparse except for the most oral part of the esophagus, where a dense mucosal innervation was found. Control experiments including WGA-HRP injections into the cervical vagus nerve, nodose ganglion injections after supranodose vagotomy, and anterograde [3H]leucine tracing from the nodose ganglion indicated that all labeled fibers in the esophagus and cardia originated from sensory neurons in the nodose ganglion. Electron microscopy revealed that labeled vagal sensory terminals related to myenteric ganglia were mostly large, mitochondria-rich profiles located predominantly on the surface of the ganglia. Specialized membrane contacts connected sensory terminals with other unlabeled profiles possibly derived from intrinsic neurons. The polarity of these contacts suggested the vagal sensory terminals to be presynaptic to intrinsic neurons of the myenteric ganglia. A hypothesis is formulated postulating a mechanoreceptive role for 'myenteric' vagal sensory terminals, providing both the brainstem (via the vagus nerve) and, by synaptic action upon intrinsic neurons, the myenteric plexus with information on tension and motility of the esophagus and cardia.

Insulin-like growth factor II in human adrenal pheochromocytomas and Wilms tumors: expression at the mRNA and protein level.

Abstract: Two forms of insulin-like growth factor (IGF) II with molecular masses of 10 and 7.5 kDa, respectively, were found in tumor tissue from human adrenal pheochromocytomas. The tumors contained 5.3-7.1 micrograms of immunoreactive IGF-II per g of tissue, which is about 20 times more than in adrenal medulla. The total bioactive IGF in the pheochromocytomas exceeded that in normal liver or kidney, which contained only the 7.5-kDa IGF-II species, by a factor of approximately equal to 100. By contrast, the amount of IGF-I was just measurable and did not vary significantly between tumor and normal tissue. The high amounts of IGF-II in the pheochromocytomas were not reflected, however, by a corresponding increase of mRNA. The opposite situation was found in Wilms tumors, where IGF-II content was in the same range as in nontumor tissues despite increased expression of IGF-II mRNA.

Immunohistochemical localization of calcium-binding proteins, parvalbumin and calbindin-D 28k, in the adult and developing visual cortex of cats: a light and electron microscopic study.

Abstract: In the cat primary visual cortex, we investigated with immunohistochemical techniques the developmental changes in the cellular and subcellular localization of the Ca2+-binding proteins parvalbumin (PV) and calbindin-D 28K (CBP), in order to determine whether there is a correlation between the expression of Ca2+-dependent processes and the time course of the critical period for use-dependent plasticity. On the 54th day of gestation and at 1 week postnatally, both calcium-binding proteins were present only in a subpopulation of neurons in layers V and VI. During subsequent maturation, the number of PV(+) and CBP(+) neurons increased significantly and labeled cells were detected in more superficial layers. Moreover, the homogeneous labeling of some CBP(+) neurons in layers IV to VI decreased and changed to a punctate pattern. In adult cats PV(+) neurons were evenly distributed throughout layers II to VI, whereas CBP(+) neurons were concentrated in layers II/III. Only a few immunoreactive cells had morphological features characteristic of pyramidal cells; the large majority were nonpyramidal. Electron microscopy confirmed the presence of PV- and CBP-reaction product within the perikarya, axons, and dendrites of labeled cells. It was associated preferentially with microtubules, postsynaptic densities, and intracellular membranes. Immunoreactive neurons received immunonegative asymmetric synapses on their dendritic shafts and made symmetric synaptic contacts with labeled and unlabeled somata and with unlabeled dendritic shafts. The large number and widespread distribution of immunoreactive neurons implies that PV and CBP play an important role in the regulation of calcium-dependent processes in the visual cortex. Furthermore, the developmental redistribution of PV and CBP points to changes in the organization of Ca2+-dependent processes during maturation.

The use of visual landmarks by honeybees: Bees weight landmarks according to their distance from the goal

Abstract: 1 Honeybees learn the location of a source of sucrose in relation to the positions of visual landmarks It is shown here that bees pay most attention to those landmarks which are close to the sucrose and which will therefore guide a bee most accurately to its goal 2 Individually marked bees were trained to collect sucrose from a reservoir whose location was specified by an array of landmarks, with individual landmarks placed at different distances from the reservoir Once trained, the bees' flight path was recorded in tests with the sucrose removed In these tests, the array of landmarks was transformed from the training configuration to provide two possible sites for the sucrose One was defined by the landmarks close to the sucrose reservoir in training, the other by more distant landmarks In all experiments (Figs1, 2 and 3), bees spent more time flying in the site defined by the close landmarks They did so even when the apparent sizes of the close and distant landmarks viewed from the reservoir were the same We conclude that bees learn the distance of landmarks from the goal, and that, during their search for the goal, they weight nearer landmarks more heavily than distant ones 3 Landmarks are also weighted according to their (apparent) size Bees were trained to find sucrose at a reservoir placed equidistantly from different-sized landmarks Tests were given with the training array stretched to provide two possible sites for the sucrose One site was specified by the large, the other by the small landmarks Bees spent more time flying in the site defined by the larger landmarks (Fig 5) 4 We discuss, with the aid of computer simulation, different ways in which the distance between landmark and goal could influence a bee's searching behaviour

Vasodilatory effects and coexistence of calcitonin gene‐related peptide (CGRP) and substance P in sensory nerves of cat dental pulp

Abstract: Substance P (SP)- and calcitonin gene-related peptide (CGRP)-immunoreactivity (-IR) were localized by immunohistochemistry in the same nerve cell bodies in the trigeminal ganglia as well as in nerve terminals of the dental pulp. The distribution of SP- and CGRP-IR nerves were identical in the dental pulp and mainly associated with blood vessels. The level of CGRP-IR in the dental pulp, as measured by radio-immunoassay (RIA), was 1.4 +/- 0.2 pmol g-1 wet wt, which is in the same range as that found for substance P. Local intra-arterial infusion of synthetic CGRP and substance P produced vasodilatation in the dental pulp as measured by both laser Doppler flowmetry and an 125I clearance technique. The CGRP was effective as a vasodilator when infused in the femtomole per minute range, and SP in the picomole range. The effect of CGRP (50 fmol min-1) was 10 times larger when given after SP (15 pmol min-1) than before it. Since the two peptides coexist in the same neurons, it is suggested that they both contribute to the vasodilation seen upon antidromic stimulation of sensory nerves.

Immune-Mediated Encephalitis: On the Role of Antigen-Presenting Cells in Brain Tissue

Abstract: The observation of impaired rejection of xenografts implanted into the brain parenchyma led to the description of the brain as an \"immune-privileged site\". Given an intact blood brain barrier, lymphocyte traffic through the central nervous system (CNS) tissue is not very likely to occur. However, an early and effective elimination of antigens, e.g. neurotropic viruses, is required also within the CNS. Indeed., intact effector functions of the immune system within the brain are evidenced by 1) the demonstration of T lymphocyte infiltrations in viral and autoimmune encephalitis (Traugott et al. 1981, 1982), 2) the successful transfer of experimental autoimmune encephalitis (EAE) with myelin basic protein (MBP)specificT cells (Paterson 1960, Ben-Nun et al. 1981), 3) the synthesis of immunoglobulins within the CNS in some forms of encephalitis (Tourtelotte & Ma 1978) and 4) the prevention of brain damage in certain experimental viral diseases by treatment with imjnunosuppressive drugs (Lipton & Dal Canto 1976). In order to fulfil the functions of the immune system within the CNS, i.e. recognition and elimination of antigens, the immune system may require regulatory elements at the interface to the CNS. As will be discussed in the following sections, the proposed regulatory system may propagate immune functions in the brain tissue but may also restrict immune reactions to an absolute minimum in order to spare the vital neuronal system. Dysfunction of the regulatory system may contribute to the development of immune-mediated encephahtis. Secretion of immunosuppressive factors may alter immunoreactivity within the CNS. A peptide with T cell suppressor activity has recently been purified from conditioned medium of cultured glioblastoma cells (see section 6).

Growth rate of human pituitary adenomas.

Abstract: ✓ The immunohistological detection of a proliferation-associated nuclear antigen by the monoclonal antibody Ki-67 allows the determination of the growth fraction in human cell populations. In this study, biopsy specimens of 31 pituitary adenomas representing all major endocrine types were examined. All adenomas contained proliferating cells and the percentage of nuclei that were immunoreactive to Ki-67 ranged from 0.1% to 3.7%. Low values (0.1% to 1.0%) were present in 11 endocrine-inactive adenomas and higher values (1.1% to 1.5%) were found in six acromegalic patients. The percentages of Ki-67-positive cells in 12 prolactinomas and two adenomas from patients with Cushing's disease covered the entire range (0.1% to 3.7%). Preoperative bromocriptine treatment of prolactinomas did not influence Ki-67 expression. Invasive adenomas, as determined by preoperative computerized tomography, surgical observation, and histological examination of the sella dura demonstrated significantly higher Ki-67 values (averag...

Growth-mechanism of giant intracranial aneurysms; demonstration by CT and MR imaging.

Abstract: In four cases of giant intracranial aneurysm, CT demonstrated a hyperdense open-, or closed-ring structure at the periphery of the aneurysm. Surgery in two of the cases demonstrated that this peripheral hyperdensity represents fresh clot inside the wall of the thrombosed mass. An analogy is established between giant intracranial aneurysms, chronic subdural hematomas and growing encapsulated intracerebral hematomas. The common feature of the three entities is slow growth by recurrent hemorrhages into the lesion. It is proven that growth of chronic subdural hematomas and of growing encapsulated hematomas is related to recurrent hemorrhage from capillaries sprouting within the membrane of the lesion. The highly vascularized membranous wall of a giant intracranial aneurysm seems to behave like the membrane of a chronic subdural hematoma. It is suggested that the giant intracranial aneurysm grows by recurrent hemorrhage into its wall and behaves like growing encapsulated hematomas.