Showing papers by "University of Zurich published in 1990"

Axonal regeneration in the rat spinal cord produced by an antibody against myelin-associated neurite growth inhibitors.

Abstract: After lesions in the differentiated central nervous system (CNS) of higher vertebrates, interrupted fibre tracts do not regrow and elongate by more than an initial sprout of approximately 1 mm. Transplantations of pieces of peripheral nerves into various parts of the CNS demonstrate the widespread capability of CNS neurons to regenerate lesioned axons over long distances in a peripheral nerve environment. CNS white matter, cultured oligodendrocytes (the myelin-producing cells of the CNS), and CNS myelin itself, are strong inhibitors of neuron growth in culture, a property associated with defined myelin membrane proteins of relative molecular mass (Mr) 35,000 (NI-35) and 250,000 (NI-250). We have now intracerebrally applied the monoclonal antibody IN-1, which neutralizes the inhibitory effect of both these proteins, to young rats by implanting antibody-producing tumours. In 2-6-week-old rats we made complete transections of the cortico-spinal tract, a major fibre tract of the spinal cord, the axons of which originate in the motor and sensory neocortex. Previous studies have shown a complete absence of cortico-spinal tract regeneration after the first postnatal week in rats, and in adult hamsters and cats. In IN-1-treated rats, massive sprouting occurred at the lesion site, and fine axons and fascicles could be observed up to 7-11 mm caudal to the lesion within 2-3 weeks. In control rats, a similar sprouting reaction occurred, but the maximal distance of elongation rarely exceeded 1 mm. These results demonstrate the capacity for CNS axons to regenerate and elongate within differentiated CNS tissue after the neutralization of myelin-associated neurite growth inhibitors.

Total removal of craniopharyngiomas. Approaches and long-term results in 144 patients.

Abstract: The clinical features, perioperative course, and postoperative outcomes of 144 patients who underwent microsurgical resection of craniopharyngioma were reviewed. Overall, 90% of the tumors were completely resected and 7% recurred. Evaluation of those patients who underwent primary resection revealed much better results. The operative techniques and approaches are reviewed in detail. The results of this series suggest that primary total removal of craniopharyngiomas yields the best long-term outcome for the patient. Experience has shown that the larger the tumor the greater will be the damage, both preoperatively and intraoperatively, to vital intracranial structures. Consequently, early diagnosis, at a stage when the tumor is still small, improves the chances of accomplishing complete removal and of achieving good operative results. The early diagnosis of craniopharyngioma, before it can produce devastating neurological defects, continues to be the principal goal of our medical and pediatric colleagues.

Tool use and tool making in wild chimpanzees.

Abstract: Reported incidences of tool use and tool making for three wild chimpanzee populations increase from Mahale (12 and 3 types of use and making, respectively), Gombe (16 and 3) to Tai (19 and 6). Sticks

Viral escape by selection of cytotoxic T cell-resistant virus variants in vivo

Abstract: Viruses persist in an immune population, as in the case of influenza, or in an individual, as postulated for human immunodeficiency virus, when they are able to escape existent neutralizing antibody responses by changing their antigens. It is now shown that viruses can in principle escape the immunosurveillance of virus-specific cytotoxic T cells by mutations that alter the relevant T-cell epitope.

Nerve sprouting in innervated adult skeletal muscle induced by exposure to elevated levels of insulin-like growth factors.

Abstract: Partial denervation or paralysis of adult skeletal muscle is followed by nerve sprouting, probably due to release of diffusible sprout-inducing activity by inactive muscle. Insulin-like growth factors (IGF1 and IFG2) are candidates for muscle-derived sprouting activity, because (a) they induce neurite growth from peripheral neurons in vitro; and (b) their mRNA levels in adult skeletal muscle increase severalfold after denervation or paralysis. We sought to determine whether the presence of elevated levels of IGFs in innervated adult skeletal muscle was sufficient to produce intramuscular nerve growth. Low concentrations of IGFs induced massive neurite growth from enriched embryonic chick motoneurons in vitro. Half-maximal responses required 0.2 nM IGF2 or IGF1, or 20 nM insulin. Similar hormone binding properties of motoneuron processes in vitro were observed. Exposure of adult rat or mouse gluteus muscle in vivo to low quantities of exogenous IGF2 or IGF1 led to intramuscular nerve sprouting. Numbers of sprouts in IGF-exposed muscles were 10-fold higher than in vehicle-exposed or untreated muscles, and 12.2% of the end plates in IGF-exposed muscle (control: 2.7%) had sprouts growing from them. The nerve growth reaction was accompanied by elevated levels of intramuscular nerve-specific growth-associated protein GAP43. Additional properties of IGF-exposed muscle included modest proliferation of interstitial cells and elevated interstitial J1 immunoreactivity. These results suggest that elevated levels of IGFs in denervated or paralyzed muscle might trigger coordinate regenerative reactions, including nerve sprouting and expression of nerve growth-supporting substrate molecules by activated interstitial cells.

Potassium conductances in hippocampal neurons blocked by excitatory amino-acid transmitters

Abstract: EXCITATORY amino acids mediate fast synaptic transmission in the central nervous system through the activation of at least three distinct ionotropic receptors: N-methyl-D-aspartate (NMDA), the α-amino-3-hydroxy-5-methyl-isoxasole-4-propionate(AMPA)/ quisqualate (QUIS) and the kainate subtypes (for reviews, see refs 1, 2). They also activate the additional QUIS 'metabotropic' receptor (sensitive to trans-l-amino-cyclopentyl-l,3-dicarboxylate, ACPD) linked to inositol phospholipid metabolism3–5. We have used hippocampal slice cultures to study the electrophysio-logical consequences of the metabotropic response. We find that activation of an ACPD-sensitive QUIS receptor produces a 'slow' excitation of CA3 pyramidal cells, resulting from depression of a Ca2+-dependent K+ current and a voltage-gated K+ current. Combined voltage-clamp and microfluorometric recordings show that, although these receptors can trigger an increase in intracellular Ca2+ concentration6–8, suppression of K+ currents is independent of changes in intracellular Ca2+. These effects closely resemble those induced by activating muscarinic acetylcholine receptors in the same neurons and suggest that excitatory amino acids not only act as fast ionotropic transmitters but also as slow neuromodulatory transmitters.

Resistance to influenza virus and vesicular stomatitis virus conferred by expression of human MxA protein.

Abstract: MxA and MxB are interferon-induced proteins of human cells and are related to the murine protein Mx1, which confers selective resistance to influenza virus. In contrast to the nuclear murine protein Mx1, MxA and MxB are located in the cytoplasm, and their role in the interferon-induced antiviral state was unknown. In this report we show that transfected cell lines expressing MxA acquired a high degree of resistance to influenza A virus. Surprisingly, MxA also conferred resistance to vesicular stomatitis virus. Expression of MxA in transfected 3T3 cells had no effect on the multiplication of two picornaviruses, a togavirus, or herpes simplex virus type 1. Treatment of MxA-expressing cells with antibodies to mouse alpha-beta interferon did not abolish the resistance phenotype. The conclusion that resistance to influenza virus and vesicular stomatitis virus was due to the specific action of MxA is further supported by the observation that transfected 3T3 cell lines expressing the related MxB failed to acquire virus resistance.

Efficient production of chicken egg yolk antibodies against a conserved mammalian protein.

Abstract: The egg yolk of immunized chicken is a rich and inexpensive source of specific polyclonal antibodies. In this paper we show that 20-30 micrograms of a highly conserved mammalian protein, as exemplified by proliferating cell nuclear antigen, are sufficient to induce an immune response. Immunoblot analysis revealed that specific antibodies appeared 20 days after immunization, reached a plateau after 30 days, and remained high until at least day 81. A total amount of 4 g immunoglobulin was extracted from 62 eggs of one immunized hen, yielding approximately 130 mg of specific antibodies.

Detection of Somatostatin Receptors in Surgical and Percutaneous Needle Biopsy Samples of Carcinoids and Islet Cell Carcinomas

Abstract: Somatostatin (SS) receptor status was investigated in the tumor tissues from 62 patients with carcinoid tumors and 15 patients with islet cell carcinomas using receptor autoradiography techniques with two different iodinated somatostatin analogues as radioligands, a [Leu8, DTrp22, Tyr25]somatostatin-28 and a somatostatin octapeptide, Tyr3-octreotide. The carcinoid tumors were either primaries (n = 32) or metastases (n = 43), sampled as surgical specimens or as small needle liver biopsies. Fifty-four of 62 carcinoid patients had SS receptor-positive tumors (87%). All 15 islet cell carcinoma patients had positive tumors (4 primaries, 11 metastases), i.e., 3 vipomas, 3 insulinomas, 2 glucagonomas, 1 gastrinoma, 2 polyfunctional tumors, and 4 nonfunctioning tumors. Saturation and competition experiments on tissue sections revealed saturable, high affinity binding sites pharmacologically specific for bioactive SS analogues. In a majority of the tumors, the receptors were densely distributed and were always homogeneously found in the whole tumor. All except two tumors were labeled with both radioligands. Multiple liver metastases (n = 16) from three different patients were all shown to contain a comparable amount of receptors. SS receptors could be demonstrated even in very small tissue samples of liver metastases obtained by percutaneous liver biopsies (mean weight, 6.8 mg). The majority of the eight SS receptor-negative carcinoids were mainly bronchial carcinoids (n = 5), usually poorly differentiated. On the contrary, SS receptor-positive cases were never found to be anaplastic. All tumors except one from patients pretreated with octreotide (3 days to 3.8 years) were SS receptor positive. In the majority of carcinoids or islet cell carcinomas, the SS receptor status correlated with the in vivo biochemical response (hormone inhibition) to octreotide. These data demonstrate (a) the high prevalence of SS receptors in the primary tumors of both carcinoids and islet cell carcinomas, (b) their presence in metastases as well, (c) their continuous expression even during long term octreotide therapy, (d) the possibility of measuring SS receptors in percutaneous needle liver biopsies, and (e) the evidence of their functionality. This study therefore suggests that tumoral SS receptors may be the likely molecular basis for octreotide action and may be an important parameter for predicting the therapeutic efficacy of SS analogues in carcinoids and islet cell carcinomas.

Interferon-induced proteins and the antiviral state.

Abstract: Publisher Summary This chapter reviews recent work on the best-characterized interferon (IFN)-induced proteins. The focus is on IFN-induced proteins with assigned functions—namely, protein kinase P1, 2-5A synthetase, mouse and human Mx proteins, indolamine 2,3-dioxygenase, and a few other IFN-induced proteins. The Mx proteins are discussed in greatest detail, because the Mx system is under investigation in the laboratory. The chapter mentions that individual IFN-induced proteins have distinct biochemical activities that lead to discrete physiological changes in IFN-treated cells. For example, the IFN-induced protein kinase P1 can inhibit the multiplication of many different viruses by reducing the translation rates of viral mRNAs. In contrast, the antiviral activities of 2-5A synthetases and Mx proteins show a high degree of specificity for particular classes of viruses. It discusses recent work on the molecular mechanisms of IFN action toward many DNA and RNA viruses.

Prevalence of acute mountain sickness in the Swiss Alps.

Abstract: OBJECTIVE--To assess the prevalence of symptoms and signs of acute mountain sickness of the Swiss Alps DESIGN--A study using an interview and clinical examination in a representative population of mountaineers Positive symptoms and signs were assigned scores to quantify the severity of acute mountain sickness SETTING--Four huts in the Swiss Alps at 2850 m, 3050 m, 3650 m, and 4559 m SUBJECTS--466 Climbers, mostly recreational: 47 at 2850 m, 128 at 3050 m, 82 at 3650, and 209 at 4559 m RESULTS--In all, 117 of the subjects were entirely free of symptoms and clinical signs of acute mountain sickness; 191 had one or two symptoms and signs; and 158 had more than two Those with more than two symptoms and signs were defined as suffering from acute mountain sickness At 4559 m 11 climbers presented with high altitude pulmonary oedema or cerebral oedema, or both Men and women were equally affected The prevalence of acute mountain sickness correlated with altitude: it was 9% at 2850 m, 13% at 3050 m, 34% at 3650 m, and 53% at 4559 m The most frequent symptoms and signs were insomnia, headache, peripheral oedema, and scanty pulmonary rales Severe headache, vomiting, dizziness, tachypnoea, and pronounced pulmonary rales were associated with other symptoms and signs and therefore characteristic of acute mountain sickness CONCLUSION--Acute mountain sickness is not an uncommon disease at moderately high altitude--that is, above 2800 m Severe headache, vomiting, dizziness, tachypnoea, and pronounced pulmonary rales indicate severe acute mountain sickness, and subjects who suffer these should immediately descend to lower altitudes

Transcription factor AP-4 contains multiple dimerization domains that regulate dimer specificity.

Abstract: Enhancer binding protein AP-4 is a transcription factor that activates both viral and cellular genes by binding to the symmetrical DNA sequence, CAGCTG. Here, we report the molecular cloning and characterization of human AP-4 cDNAs. The deduced amino acid sequence reveals that AP-4 is a helix-loop-helix (HLH) protein. Like other members of this family, the AP-4 HLH motif and the adjacent basic domain are necessary and sufficient to confer site-specific DNA binding. However, unlike other HLH proteins, AP-4 also contains two additional protein dimerization motifs consisting of leucine repeat elements LR1 and LR2. The analysis of various deletion and point mutants for their ability to dimerize in the presence or absence of DNA reveals several unusual features. Although the HLH basic region is sufficient for DNA recognition and binding, dimer formation between different truncated versions of AP-4 in solution requires an intact LR1 or LR2 domain. AP-4 is unable to form heterodimers with other helix-loop-helix family members such as the immunoglobulin enhancer binding factor, E12. In contrast, an AP-4 derivative, delta C222, which lacks LR1 and LR2 but retains an intact HLH, can form heterodimers with E12. Moreover, AP-4 molecules containing LR2 or LR1 are unable to form mixed dimers with carboxy-terminally truncated AP-4 molecules such as delta C222, but retain the ability to form complexes with longer versions of AP-4 that contain LR1 and/or LR2. Our findings strongly suggest that AP-4 contains multiple protein-protein interfaces that function to promote homodimer formation and restrict heterocomplexes. These findings provide a mechanism by which different members of the helix-loop-helix family of transcription factors can form functional dimers in a specific fashion with their appropriate partners to control transcriptional networks during cellular differentiation.

Increased Secretion of Tumor Necrosis Factor α, Interleukin 1, and Interleukin 6 by Human Mononuclear Cells Exposed to β-Galactoside-specific Lectin from Clinically Applied Mistletoe Extract

Abstract: A β-galactoside-specific lectin from proprietary mistletoe extract, recently reported to exhibit immunomodulatory potency in vivo (T. Hajto, K. Hostanska, and H-J. Gabius, Cancer Res. 49: 4803–4808, 1989), induced increased secretion of tumor necrosis factor α, interleukin 1, and interleukin 6 in cultures of human peripheral blood mononuclear cells. The enhancement of secretion, determined independently by bioassays and enzyme-linked immunosorbent assay-based quantitation, was caused by selective protein-carbohydrate interaction, as revealed by the strict dependence on the presence of the carbohydrate-binding subunit of the lectin and the reduction of the effect of the lectin in the presence of the specific lectin-binding sugar as well as anti-lectin antibodies. Increased cytokine levels in serum of patients after injection of optimal lectin doses corroborated the in vitro results. Thus, these data provide an explanation for the increases in cellular parameters of the host defense system in vivo , which presents a further step toward their potentially beneficial clinical exploitation in standardized regimens.

Parvalbumin-containing gabaergic interneurons in the rat neostriatum

Abstract: Antibodies to the intracellular calcium binding protein parvalbumin were shown to label specifically a distinct group of neostriatal GABAergic neurons. These neurons corresponded to the intensely staining subclass of neostriatal GABAergic neurons that have previously been shown to be a class of aspiny interneurons in the neostriatum. The parvalbumin neurons were aspiny neurons with varicose dendrites distributed throughout the neostriatum in a pattern identical to the intensely stained GABA neurons, and both populations of neurons showed increased numbers in the lateral part of the neostriatum. Double labeling of single neurons with both the GABA and parvalbumin antisera showed that all parvalbumin neurons were positive for GABA, but some GABA labelled neurons were not immunoreactive for parvalbumin. These parvalbumin-negative GABAergic neurons were morphologically similar to the spiny projection neurons, which are GABAergic but usually are not so heavily stained. The relationship of the GABA-containing parvalbumin neurons to the striatal mosaic organization was determined by using immunocytochemistry for another calcium binding protein, calbindin D28K, to label the matrix compartment of the striatum. The distribution of parvalbumin-positive neurons relative to the calbindin-positive matrix and calbindin-poor patches was determined by using pairs of adjacent sections stained with the calbindin and parvalbumin antisera. This analysis showed that the somata of the parvalbumin neurons were present in both patch and matrix compartments, and their axons and dendrites crossed the boundaries between compartments. A quantitative analysis of the number of neurons in each compartment revealed that the neurons showed no preferential distribution in either compartment, but instead were present according to the area occupied by that compartment. Approximately 10% of parvalbumin neurons were in the patch compartment, and in these same sections, the patch compartment occupied approximately 10% of the area of those sections. Staining with parvalbumin antibodies can therefore be used to identify a single class of GABAergic aspiny interneurons that is present in both patch and matrix compartments, and whose processes cross the borders between these compartments.

Oligodendrocytes arrest neurite growth by contact inhibition.

Abstract: We have used video time-lapse microscopy to analyze in vitro the interactions of growth cones of newborn rat dorsal root ganglion cells with dissociated young rat CNS glial cells present in the cultures at low density. To provide optimal conditions for neurite extension, cells were grown on laminin and in NGF-supplemented medium. Our initial observation showed that there are 2 subpopulations of growth cones differing in their growth rate on laminin (averages of 12 and 45 microns/hr). When these growth cones encountered astrocytes, they maintained their normal configuration and growth velocity. They subsequently grew along or on top of astrocytes. In some cases, however, fast-moving growth cones showed a slight reduction in their growth rate. When growth cones countered oligodendrocytes, however, firm filopodial contact was sufficient to induce a rapid and long- lasting arrest of the growth cone motility, often followed by a collapse of the growth cone structure. One third of the paralyzed growth cones were observed to retract. Growth arrest and growth cone collapse were strictly dependent on membrane contact between neurons and oligodendrocytes. This contact inhibition phenomenon was exclusively found with differentiated oligodendrocytes and could be prevented by the monoclonal antibody IN-1 directed against neurite growth inhibitors NI-35 and NI-250 (Caroni and Schwab, 1988b). These results confirm previous findings that the neurite growth inhibitor proteins are important in axon outgrowth. Further, the inhibition of neurite growth exerted by oligodendrocytes is a contact-mediated phenomenon that can be triggered by the tip of growth cone filopodia.

Fecundity, metabolism, and body size in Anopheles (Diptera: Culicidae), vectors of malaria.

Abstract: In four Anopheles species, An. albimanus, An. gambiae, An. stephensi , and An. quadrimaculatus Say, total protein, lipid, and carbohydrate present at eclosion, after feeding on sucrose, and after extreme starvation were quantified to study the effect of teneral and maximal reserves on subsequent fecundity and to judge the extent of reserve mobilization and the minimal irreducible amounts required for survival. All parameters were regressed on body size, presented as the cubic value of wing length. Teneral reserves were isometric with body size, were considerably lower than previously reported for Aedes aegypti (L.) and were sexually dimorphic with respect to reserves and body size, all being slightly reduced in males. On the average, up to 70% of the teneral female lipids and up to 50% of their teneral protein could be mobilized during nutritive stress. Conversely, access to sucrose for a few days led to a pronounced glycogenesis (up to 509%) and lipogenesis (up to 450% of the teneral values), depending on the species. In absolute terms, lipogenesis prevailed over glycogenesis. On a caloric basis, up to 30% of the blood meal protein was utilized for synthesis of yolk protein and lipid, and another 15% was deposited as an extra-ovarian, maternal protein and lipid store, perhaps compensating for the limited teneral reserves. A complete nitrogen budget revealed that in a given class of body size, roughly 80% of the blood meal protein was catabolized and excreted through the three major pathways of uricotely, ureotely, and ammonotely. Quantification of the hematin in fecal samples allowed a stoichiometrical determination of the amount of blood ingested. Eco-physiological aspects of larval feeding, teneral reserves, blood meal utilization, and possible behavioral adaptations to these physiological constraints are discussed and compared with previous data on culicine mosquitoes, stressing the invalidity of generalizations among these taxa.

Stein's method for diffusion approximations

Abstract: Stein's method of obtaining distributional approximations is developed in the context of functional approximation by the Wiener process and other Gaussian processes. An appropriate analogue of the one-dimensional Stein equation is derived, and the necessary properties of its solutions are established. The method is applied to the partial sums of stationary sequences and of dissociated arrays, to a process version of the Wald-Wolfowitz theorem and to the empirical distribution function.

Production of hemopoietic colony-stimulating factors by astrocytes.

Abstract: Astrocytes may play a central role in regulation of immune mediated processes in the central nervous system. By their inducible expression of MHC class II Ag and secretion of cytokines they may propagate expansion and activation of T and B lymphocytes invading the brain tissue. Here we report that astrocytes may also contribute to the macrophage response observed in inflammatory and degenerative diseases of the brain. Murine astrocytes secrete granulocyte-macrophage CSF (GM-CSF) as evidenced by induction of colony formation in bone marrow cells and growth of FDC-P1 cells. Both effects are neutralized with anti-GM-CSF- but not with anti-IL-3-antibodies. Some residual activity detected in the bone marrow assay after antibody treatment can be explained by concomitant production of granulocyte CSF (G-CSF). The mRNA of both G- and GM-CSF are identified by Northern blots in astrocytes. Furthermore, mRNA for IL-1 alpha and IL-1 beta are detected in comparable amounts in astrocytes and brain macrophages, the latter, however, comprising much more potent sources of TNF-alpha.

Time course of EEG power density during long sleep in humans

Abstract: In nine subjects sleep was recorded under base-line conditions with a habitual bedtime (prior wakefulness 16 h; lights off at 2300 h) and during recovery from sleep deprivation with a phase-advanced bedtime (prior wakefulness 36 h; lights off at 1900 h). The duration of phase-advanced recovery sleep was greater than 12 h in all subjects. Spectral analysis of the sleep electroencephalogram (EEG) revealed that slow-wave activity (SWA; 0.75-4.5 Hz) in non-rapid-eye-movement (NREM) sleep was significantly enhanced during the first two NREM-REM sleep cycles of displaced recovery sleep. The sleep stages 3 and 4 (slow-wave sleep) and SWA decreased monotonically over the first three and four NREM-REM cycles of, respectively, base-line and recovery sleep. The time course of SWA in base-line and recovery sleep could be adequately described by an exponentially declining function with a horizontal asymptote. The results are in accordance with the two-process model of sleep regulation in which it is assumed that SWA rises as a function of the duration of prior wakefulness and decreases exponentially as a function of prior sleep. We conclude that the present data do not provide evidence for a 12.5-h sleep-dependent rhythm of deep NREM sleep.

Antiviral cytotoxic t cell response induced by in vivo priming with a free synthetic peptide

Abstract: Induction in vivo of antiviral cytotoxic T cell response was achieved in a MHC class I-dependent fashion by immunizing mice three times with a free unmodified 15-mer peptide derived from the nucleoprotein of lymphocytic choriomeningitis virus in IFA. The effector T cells are CD8+, restricted to the class I Ld allele of the analyzed mouse strain, and are specific both at the level of secondary restimulation in vitro and at the effector T cell level. These results suggest that cocktails of viral peptides may be used as antiviral T cell vaccines.