PubMed Health⌕ Search

Biomedical subjects

C Corti

Publications and source records attributed to C Corti.

At least 37 records · Page 2Linked to original sources
PubMed1998

Differential expression of SAPK isoforms in the rat brain. An in situ hybridisation study in the adult rat brain and during post-natal development.

MAPK pathways transduce a broad variety of extracellular signals into cellular responses. Despite their pleiotropic effects and their ubiquitous distribution, surprisingly little is known about their involvement in the communication network of nerve cells. As a first step to elucidate the role of MAPK pathways in neuronal signalling, we studied the distribution of SAPK alpha/JNK2, SAPK beta/JNK3, and SAPK gamma/JNK1, three isoforms of SAPK/JNK, a stress-activated MAPK subfamily. We compared the mRNA localisation of the three main isoforms in the adult and developing rat brain using in situ hybridisation. In the adult brain, SAPK alpha and beta were widely but heterogeneously distributed, reproducing the pattern of a probe that does not discriminate the isoforms. Differently, high labelling for the SAPK gamma probe was exclusively localised in the endopiriform nucleus and medial habenula. Intermediate staining was detected in the hippocampus. During post-natal development, SAPK beta showed the same localisation as in the adult. Nevertheless, the semi-quantitative analysis of optical densities showed significantly different mRNA levels. In the adult, SAPK gamma signal was weak, whereas in newborn rats the labelling was intense and widely distributed. SAPK gamma mRNA levels decreased during development, to reach the low signals detected in the adult. These results suggest that in the central nervous system SAPK-type MAP kinases perform significant physiological functions which are particularly relevant during post-natal development. The distinct distribution patterns of SAPK isoforms in the adult rat brain support the hypothesis that separate functions are performed by the products of the three SAPK genes.

Animals↗
PubMed1998

Phosphorylation of calmodulin alters its potency as an activator of target enzymes.

Previous work has shown that calmodulin (CaM) is constitutively phosphorylated in rat liver, probably by casein kinase II [Quadroni, M., James, P., and Carafoli, E. (1994) J. Biol. Chem. 269, 16116-16122]. A procedure is now described for the isolation of the phosphorylated forms of calmodulin (PCaM) free from CaM, since in vitro phosphorylation experiments yield a 50:50 mixture of 3-4 times phosphorylated CaM and native CaM. The activation of six target enzymes by PCaM was tested: myosin light chain kinase, 3',5'-cyclic nucleotide phosphodiesterase, plasma membrane Ca2+-ATPase, Ca2+-CaM-dependent protein phosphatase 2B (calcineurin), neuronal nitric oxide synthase, and CaM-kinase II. In general, the phosphorylation of CaM caused a decrease in enzyme binding affinity, increasing the Kact by 2-4-fold for MLCK, PDE, PM Ca2+-ATPase, and calcineurin. The Vmax at saturating concentrations of PCaM was less affected, with the exception of CaM-kinase II, which was only minimally activated by PCaM and NOS whose Vmax was increased 2.6 times by PCaM with respect to CaM. Phosphorylation of calmodulin had very little effect on the binding of calcium to the enzyme despite the fact that Ser 101 which is phosphorylated is located in the third calcium binding loop. CD measurements performed on CaM and PCaM indicated that phosphorylation causes a marked decrease in the alpha-helical content of the protein. Phosphorylated CaM is very prone to dephosphorylation and was thus tested as a substrate for several phosphatases. It was unaffected by calcineurin (PP2B), but was a reasonable substrate for the pleiotropic phosphatases PP1gamma and PP2A.

Animals↗
PubMed1998

VIP (etoposide, ifosfamide and cisplatinum) as a salvage intensification program in relapsed or refractory Hodgkin's disease.

Forty-two patients with refractory (15 patients) or relapsed (27 patients) Hodgkin's disease (HD) were included in a prospective single center study evaluating the efficacy of a regimen VIP combining etoposide 75 mg/m2/day days 1-5, ifosfamide 1.2 g/m2/day days 1-5 and cisplatinum 20 mg/m2/day days 1-5, one course every 4 weeks as salvage therapy in patients with refractory or relapsed Hodgkin's disease, potentially eligible for high-dose chemotherapy with reinjection of hematopoietic stem cells (HSC). If patients were considered chemosensitive after two courses of VIP, high-dose chemotherapy followed by the reinjection of HSC was planned. After two courses of VIP, 67% achieved an objective response including 38% complete responses. Overall, 28 patients went on to high-dose therapy with reinjection of HSC, and 46% of grafted patients are in a sustained complete remission. When the overall patient population is considered, 33% are in complete remission (CR) with a median follow-up of 37 months. A CR of less than 12 months and refractory disease were associated with a poor survival. These results showed that the VIP regimen is effective in relapsed or refractory HD and allows high-dose therapy to be given in the case of most responding patients. However, results in patients with refractory disease or a first complete remission of less than 12 months need to be further improved.

Adolescent↗
PubMed1998

Cloning and characterization of alternative mRNA forms for the rat metabotropic glutamate receptors mGluR7 and mGluR8.

Novel mRNA isoforms for two members of the group III metabotropic glutamate receptors (mGluRs), called mGluR7b and mGluR8b, were identified from rat brain cerebral cortex and hippocampus. In both cases, the alternative splicing is generated by a similar out-of-frame insertion in the carboxyl-terminus that results in the replacement of the last 16 amino acids of mGluR7 and mGluR8 by 23 and 16 different amino acids, respectively. Distribution analysis for mGluR7 and mGluR8 isoforms revealed that the two splice variants are generally coexpressed in the same brain areas. The few exceptions were the olfactory bulb, in which only the mGluR7a form could be detected by reverse transcription-polymerase chain reaction, and the lateral reticular and ambiguous nuclei, which showed only mGluR8a labelling. Despite expression in the same regions, different mRNA abundance for the two variants of each receptor were observed. When transiently coexpressed in HEK 293 cells with the phospholipase C-activating chimeric G alpha qi9-G-protein, the a and b forms for both receptor subtypes showed a similar pharmacological profile. The rank order of potencies for both was: DL-amino-4-phosphonobutyrate > L-serine-O-phosphate > glutamate. However, the agonist potencies were significantly higher for mGluR8a, b compared with mGluR7a,b. In Xenopus oocytes, glutamate evoked currents only with mGluR8 when coexpressed with Kir 3.1 and 3.4. Glutamate-induced currents were antagonized by the group II/III antagonist (RS)-alpha-cyclopropyl-4-phosphonophenylglycine. In conclusion, the two isoforms of each receptor have identical pharmacological profiles when expressed in heterologous systems, despite structural differences in the carboxyl-terminal domains.

Alternative Splicing↗
PubMed1998

Role of sympathetic nervous system in hypertension and effects of cardiovascular drugs.

The sympathetic nervous system (SNS) plays an important role in the regulation of cardiac performance and peripheral circulation. Changes in SNS activity measured as catecholamines in plasma or organ spillover have been implicated in the pathogenesis of hypertension. Recent studies using microneurography to directly assess peripheral sympathetic nerve activity have demonstrated an increase in sympathetic activity in patients with borderline hypertension at rest and during hypoxia. We have recently shown that resting muscle sympathetic nerve activity is comparable in offspring of hypertensive and normotensive parents. However, during mental arithmetic the increase in muscle sympathetic nerve activity and blood pressure was significantly more pronounced in offspring of hypertensive than in offspring of normotensive parents, but resting blood pressure was in the normotensive range and comparable in both groups. These data indicate that the response to mental stress results in a more pronounced activation of SNS in normotensive subjects with a genetic background of hypertension. In other cardiovascular disease states such as acute myocardial infarction and heart failure activity of the SNS may determine prognosis significantly. Some calcium antagonists which are successfully used to treat patients with hypertension and stable angina pectoris may have unfavourable effects in patients with impaired left ventricular function. This could be due in part to baroreceptor-mediated activation of the SNS, an effect which seems to be related to pharmacokinetics and pharmacodynamics of the drugs. In contrast, angiotensin converting enzyme inhibitors seem to directly decrease sympathetic nerve activity. This may explain at least in part their beneficial effects in patients with impaired left ventricular function. Thus, the SNS as a regulator of the cardiovascular system also plays an important role in the pathophysiology of cardiovascular diseases such as hypertension, myocardial infarction and heart failure. Furthermore, drug therapy could have a significant impact on the activity of the SNS.

Arousal↗
PubMed1997

Evidence against a permissive role of the metabotropic glutamate receptor 1 in acute excitotoxicity.

Excitotoxicity has been proposed to contribute to neuronal loss in a broad spectrum of neurodegenerative conditions such as ischemia, hypoglycaemic coma or cerebral trauma. Excitotoxic neuronal injury appears to be mediated mainly by the over-activation of glutamate receptors, especially N-methyl-D-aspartate receptors, with subsequent excessive Ca2+ influx. Concurrent with the activation of glutamate-gated ion channels, metabotropic glutamate receptors (mGluR), which are G-protein coupled receptors, are also expected to be activated. Excessive stimulation of phospholipase C-coupled mGluR, mGluR1 and mGluRS, has been suggested to have neurotoxic consequences. However, the contribution of mGluR activation on excitotoxicity is still unclear and controversial. Here we report that, following ischemic and excitotoxic brain injuries, inactivation of mGluR1 does not prevent excitotoxic neuronal damage. Given the evidence that agonists at this group of mGluR promoted neuronal death in cerebrocortical cultures after oxygen-glucose deprivation or after N-methyl-D-aspartate exposure, our findings suggest that mGluR-mediated excitotoxicity is unlikely associated with mGluR1 but rather with other PLC-coupled mGluR.

Analysis of Variance↗
PubMed1996

H+-induced membrane insertion of influenza virus hemagglutinin involves the HA2 amino-terminal fusion peptide but not the coiled coil region.

Fusion of influenza virus with target membranes is induced by acid and involves complex changes in the viral envelope protein hemagglutinin (HA). In a first, kinetically distinct step, the HA polypeptide chain 2 (HA2) is inserted into the target membrane bilayer. Using hydrophobic photolabeling with the phospholipid analogue 1-O-hexadecanoyl-2-O-[9-[[[2-[125I]iodo-4(trifluoromethyl-3H-diazirin -3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine, we identified the segment within HA2 that interacts with the membrane. The sole part of the HA2 ectodomain that was labeled with the membrane-restricted reagent is the NH2-terminal fusion peptide (residues 1-22). No labeling occurred within the long coiled coil region generated during the acid-induced conformational transition (Bullough, P. A., Hughson, F. M., Skehel, J. J., and Wiley, D. C. (1994) Nature 371, 37-43). These data strongly suggest that the coiled coil region of HA2 does not insert into the lipid bilayer. This conclusion is at variance with the recent suggestion (Yu, Y. G., King, D. S., and Shin, Y.-K.(1994) Science 266, 274-276) that the coiled coil of HA may splay apart and insert into the target membrane, providing a mechanism by which the viral and the target membrane may come in close apposition.

Animals↗
PubMed1996

High incidence of secondary myelodysplastic syndromes following PROMACE-MOPP and involved field radiotherapy for localized gastric non-Hodgkin's lymphomas.

The incidence of secondary myelodysplastic syndromes (MDS) are rarely reported in an homogeneous patient population treated for non-Hodgkin's lymphoma (NHL). Less than 10 per cent of secondary MDS are usually observed in patients treated for Hodgkin's disease and NHL. Data on the incidence of secondary MDS induced by modern chemotherapeutic regimens is needed. Between January 1985 and January 1989, 20 patients with localized gastric non-Hodgkin's lymphomas (stage I to IIE) were prospectively treated at the Institut Gustave-Roussy with PROMACE-MOPP multi-agent chemotherapy and involved-field irradiation. The mean age was 54 years (range 23 to 69 years). Seven patients died while on therapy or relapsed 2 to 28 months after therapy. Thirteen patients were followed up for at least 5 years. Three of the 13 long-term survivors (23 per cent) developed a myelodysplastic syndrome (MDS) 48, 62 and 72 months after the end of therapy. Cytogenetic analysis was performed in two cases and showed-7 and 18q- in one case, t(9;21)(q13;q22), 21q+, i17q in the other case. PROMACE-MOPP plus radiotherapy should not be recommended in patients with localized gastric non-Hodgkin's lymphoma due to the high risk of developing secondary myelodysplastic syndromes.

Adult↗
PubMed1996

Spontaneous lung metastases in a human lung tumor xenograft: a new experimental model.

The cell line NIH-H460, derived from a human large-cell carcinoma of the lung, because metastatic in the lung of athymic mice after S.C. injection. Using serial S.C. passages of the lung metastasis, a cell line was selected, H460M, which was characterized by an increased metastatic potential compared to the parental cells after s.c. (Spontaneous metastases) or i.v. injection (experimental metastases). For the high frequency of lung metastases in the mouse and the short time required to develop metastatic foci, the H460M cells transplanted in nude mice represent a unique preclinical model for biological and therapeutic studies. The paper describes the growth and some biological properties (invasion and migration capability, membrane profile) of this experimental in vivo model.

Animals↗
PubMed1996

Progressive versus catastrophic disability: a longitudinal view of the disablement process.

BACKGROUND: There is little epidemiologic data on the development of disability over time in older persons. This study uses prospective data from cohorts followed annually for 6 to 7 years to identify persons who developed severe disability and to characterize the time course of their disabling process and subsequent mortality. METHODS: Incidence rates of severe disability, defined as need for help in three or more activities of daily living (ADLs), were estimated for 6,640 persons who had not reported severe disability at baseline and at the first four annual follow-up visits. Among persons developing severe disability, those who reported no need for help in ADLs in previous interviews were defined as cases of catastrophic disability, and those who had previously reported some disability in ADLs were defined as cases of progressive disability. RESULTS: Overall, 212 subjects developed progressive and 227 developed catastrophic disability. The rates of progressive disability and catastrophic disability were 11.3 and 12.1 cases per 1,000 person-years, respectively. For both types of disability, incidence rates increased exponentially with age, but the increase was steeper for progressive disability. At ages 70-74, less than 25% of severe disability was progressive, while over age 85 progressive disability represented more than half of severe disability. Incidence rates of total and both types of severe disability were similar in men and women. Mortality after severe disability onset was extremely high. Survival was unrelated to age at disability onset and type of disability but was significantly longer in women than in men (median 3.44 vs 2.12 years; p < .0001). CONCLUSION: Tracking the development of disability provides new and important insights into the disability experience in older men and women that are potentially relevant in planning preventive, intervention, and long-term care strategies.

Activities of Daily Living↗
PubMed1995

Successful local regional therapy with topotecan of intraperitoneally growing human ovarian carcinoma xenografts.

The therapeutic effects of intraperitoneal topotecan, a water-soluble camptothecin analogue, were investigated in two models of human ovarian carcinoma xenografted intraperitoneally into nude mice: the IGROV-1 tumour, which originated from an untreated patient, and the A2780 tumour, selected for resistance in vitro to cisplatin (A2780DDP). In IGROV-1 tumour-bearing mice, the optimal dose (10 mg kg-1) of topotecan, given intraperitioneally every 4 days for four occasions markedly increased survival time over control mice (300 T/C%) and cured 4/9 mice, and such effects were not achieved by any of the clinically available drugs tested, i.e. cisplatin carboplatin and doxorubicin delivered intraperitonally according to their optimal doses and schedules. In the treatment of A2780DDP tumour-bearing mice, topotecan was very effective since, at dose levels of 6.6 and 10 mg kg-1 every 4 days for four occasions, 15/18 mice survived more than 100 days, and most of them (12/15) were found to be tumour free. The high responsiveness of this tumour to topotecan might be related to the elevated expression of the target enzyme topoisomerase I. From these results, intraperitoneal treatment with topotecan appears to be a promising approach in the therapy of refractory ovarian cancer confined to the peritoneal cavity.

Animals↗
PubMed1993

[Correlations between membrane integrins and granulocyte defects in myelodysplastic syndromes].

The aim of the present study was to evaluate some functions of neutrophil granulocytes (PMNs), such as aggregation, superoxide production, chemotaxis and adhesion molecules involved in these processes, in 22 patients suffering from Myelodysplastic Syndrome (MDS), to clarify if granulocytes alterations described in this syndrome is really correlated with the expression of surface membrane integrins. Several patients suffering from MDS present granulocytopenia and/or absolute monocytoses; neutrophil granulocytes can have typical nuclear and cytoplasmatic alterations. These granulocytic anomalies are valuable in about 90% of patients suffering from MDS. The granulocytes showed a significant deficit in chemotaxis stimulated by serum activated with E. Coli, casein and formyl-methionyl-leucylphenylalanine (fMLP) (p < 0.01) and in superoxide production stimulated by phorbol-myristate-acetate (PMA). We also studied the role of membrane integrin CD11/CD18 using specific monoclonal antibodies (MoAb). The cytofluorimetric analysis demonstrated a significant inhibition in expression of CD11b/CD18 receptors in patients suffering from MDS (p < 0.001), while the expression of CD11a/CD18 and CD11c/CD18 receptors was normal. In conclusion we found specific alterations in PMNs functions in MDS and a correlation of these anomalies with membrane integrins of PMNs is therefore possible.

Adult↗
PubMed1991

Autoimmune thyroiditis following interleukin-2 and LAK cell therapy for metastatic renal cell carcinoma: correlation with tumor regression.

A 63-year-old woman receiving recombinant interleukin-2 (rIL-2) + lymphokine activated killer cells for metastatic renal cell carcinoma developed autoimmune thyroiditis with clinical hypothyroidism and high titer anti-thyroglobulin and anti-microsomal antibodies. The onset of thyroid dysfunction was associated with tumor regression and resulted in complete response at the end of the treatment. Cytologic and cytofluorimetric studies on thyroid tissue showed two distinct populations, mainly consisting of small lymphocytes and large thyrocytes, and the latter expressed MHC class II antigens. After completion of rIL-2 treatment, hypothyroidism gradually decreased until resolution; complete tumor remission lasted 18 months. Mechanisms underlying the association between autoimmune thyroiditis and cancer regression are discussed.

Carcinoma, Renal Cell↗
PubMed1989

Berger's disease with polyarteritis nodosa.

We describe a patient with Berger's disease and polyarteritis nodosa. This association has not been described previously in the literature. A causal relationship between the two diseases is suggested.

Adolescent↗