Biomedical subjects

A Merighi

Publications and source records attributed to A Merighi.

At least 37 records · Page 2Linked to original sources

PubMed1997

In vivo study of the kinetics of thiamine and its phosphoesters in the deafferented rat cerebellum.

The effects of chemical (CD) and surgical (SD) deafferentation of the cerebellum on different steps of the metabolism of thiamine (Th), thiamine monophosphate (ThMP) and thiamine pyrophosphate (ThPP) were evaluated in vivo in rats. CD was carried out by i.p. injection of 3-acetylpyridine, followed by harmaline and niacinamide. SD was carried out by complete dissection of the peduncles of the left cerebellar hemisphere. Under steady state condition the radioactivity of Th and its phosphoesters was determined in plasma and whole cerebellum after an i.p. injection of thiazole-[2(14)C]-thiamine (30 micrograms:1.25 micro Ci). Analytical data were processed by using an improved mathematical compartmental model, which allowed the calculation of fractional rate constants (FRC), turnover rates (TR) and turnover times (TT). Both CD and SD caused a significant reduction of TR values for Th phosphorylation to ThPP, dephosphorylation of ThPP to ThMP and Th, and ThMP, but not Th, release. TT for all Th compounds were increased compared to controls, indicating a general slowing of thiamine metabolism in the deafferented cerebellum. These results indicate an imbalance in the thiamine metabolism resulting from the impaired activity of cerebellar neurons. The possible implications of the changes in rate of Th compound turnover with respect to biochemical changes in cerebellar ataxia are discussed.

Afferent Pathways↗

PubMed1997

Portal hypertensive gastropathy: reproducibility of a classification, prevalence of elementary lesions, sensitivity and specificity in the diagnosis of cirrhosis of the liver. A NIEC multicentre study. New Italian Endoscopic Club.

OBJECTIVE: To classify elementary endoscopic lesions of portal hypertensive gastropathy, assess their reproducibility, prevalences, sensitivity and specificity in the diagnosis of cirrhosis of the liver. METHODS: 1) A classification of portal hypertensive gastropathy elementary lesions was defined. 2) Thirty-two endoscopists evaluated videotapes of endoscopic examinations of patients with liver cirrhosis to assess beyond-chance agreement (kappa). 3) Fifteen centres enrolled consecutive patients with or without cirrhosis of the liver and recorded portal hypertensive gastropathy pattern according to its location. RESULTS: 1) Four elementary lesions (Mosaic-Like Pattern, Red Point Lesions, Cherry Red Spots, Black-Brown Spots) were identified, and graded. 2) A fair to good beyond-chance agreement was obtained for all 4 lesions. 3) portal hypertensive gastropathy prevalence was higher in patients with cirrhosis of the liver (0.63, sensitivity) than in controls (0.17). Mosaic-like pattern was the most prevalent sign (0.54). Specificity of portal hypertensive gastropathy was 0.83. Portal hypertensive gastropathy was tentatively classified as mild or severe when mosaic-like pattern alone or red marks of any kind were present, respectively; this classification led to a further improvement in reproducibility. CONCLUSIONS: Our results suggest that a sufficient degree of agreement can be achieved in recording portal hypertensive gastropathy. Therefore, the New Italian Endoscopic Club classification should be used to evaluate the natural history of this condition.

Diagnosis, Differential↗

PubMed1996

Affinity purification and characterization of protein gene product 9.5 (PGP9.5) from retina.

Protein gene product 9.5 (PGP9.5) is a cytosolic protein that is highly expressed in vertebrate neurons, which is now included in the ubiquitin C-terminal hydrolase subclass (UCH) on the basis of primary-structure homology and hydrolytic activity on the synthetic substrate ubiquitin ethyl ester (UbOEt). Some UCHs show affinity for immobilized ubiquitin, a property exploited to purify them. In this study we show that this property can also be applied to PGP9.5, since a protein has been purified to homogeneity from bovine retina by affinity chromatography on a ubiquitin-Sepharose column that can be identified with: (a) PGP9.5 with respect to molecular mass, primary structure and immunological reactivity; (b) the known UCHs with respect to some catalytic properties, such as hydrolytic activity on UbOEt, (which also characterizes PGP9.5), Km value and reactivity with cysteine and histidine-specific reagents. However, it differs with respect to other properties, e.g. inhibition by UbOEt and a wider pH range of activity.

Amino Acid Sequence↗

PubMed1996

Connections of two types of flat cone bipolars in the rabbit retina.

The synaptic connections of two types of cone bipolar cells in the rabbit retina were studied with the electron microscope after labeling in vitro with 4',6-diamidino-2-phenylindole (DAPI), intracellular injection with Lucifer Yellow, and photooxidation (Mills and Massey [1992] J. Comp. Neurol. 321:133). Both types of bipolars belong to the flat variety, because they make basal junctions with a group of four to ten neighboring cone pedicles. One cell type has an axonal arborization that occupies strata 1 through 3 of the inner plexiform layer (IPL). At ribbon synaptic junctions, it is presynaptic to ganglion cell dendrites and to reciprocal dendrites belonging to narrow-field bistratified (AII) amacrine cells. In addition, it contacts and is contacted by other amacrine cell processes of unknown origin. The other cell type has an axonal arborization entirely confined to stratum 2 of the IPL; it is pre- or postsynaptic to a pleomorphic population of amacrine cell processes, and, in particular, it receives input from the lobular appendages of AII. Thus, these two bipolar types probably belong to the off-variety because they make basal junctions with cone photoreceptors and send their axon to sublamina a of the IPL, which is occupied by the dendrites of off-ganglion cells. They are also part of the rod pathway because they receive input from AII amacrine cells.

Animals↗

PubMed1996

Alpha but not beta interferon is useful in chronic active hepatitis due to hepatitis C virus. A prospective, double-blind, randomized study.

Interferon-alpha has been widely used in chronic hepatitis C, but controlled studies with intramuscular interferon-beta are lacking. We therefore performed a prospective, double-blind, randomized study comparing intramuscular IFN-alpha and -beta in patients with chronic hepatitis C. Sixty patients were randomly assigned to receive 3 MU thrice weekly intramuscularly of either recombinant IFN-alpha or leukocyte IFN-alpha or fibroblast IFN-beta for six months. Nine of 20 patients (45.0%) in the recombinant IFN, 5/19 (26.3%) in the leukocyte IFN, and none in the IFN-beta group had a complete response during therapy (recombinant IFN vs IFN-beta: P < 0.01). Only in IFN-alpha-treated patients, was infection with a single HCV genotype (type 2a or 2b) associated with significantly better long-term outcome. IFN-alpha is useful in chronic hepatitis C while intramuscular IFN-beta interferon does not exert any beneficial effect. This is probably due to an insufficient bioavailability of IFN-beta when given intramuscularly.

Adolescent↗

PubMed1996

The early intracellular signaling pathway for the insulin/insulin-like growth factor receptor family in the mammalian central nervous system.

Several studies support the idea that the polypeptides belonging to the family of insulin and insulin-like growth factors (IGFs) play an important role in brain development and continue to be produced in discrete areas of the adult brain. In numerous neuronal populations within the olfactory bulb, the cerebral and cerebellar cortex, the hippocampus, some diencephalic and brainstem nuclei, the spinal cord and the retina, specific insulin and IGF receptors, as well as crucial components of the intracellular receptor signaling pathway have been demonstrated. Thus, mature neurons are endowed with the cellular machinery to respond to insulin and IGF stimulation. Studies in vitro and in vivo, using normal and transgenic animals, have led to the hypothesis that, in the adult brain, IGF-I not only acts as a trophic factor, but also as a neuromodulator of some higher brain functions, such as long-term potentiation and depression. Furthermore, a trophic effect on certain neuronal populations becomes clearly evident in the ischemic brain or neurodegenerative disorders. Thus, the analysis of the early intracellular signaling pathway for the insulin/IGF receptor family in the brain is providing us with new intriguing findings on the way the mammalian brain is sculpted and operates.

Adult↗

PubMed1996

Dorsal rhizotomy induces transient expression of the highly sialylated isoform of the neural cell adhesion molecule in neurons and astrocytes of the adult rat spinal cord.

Expression of the weakly adhesive, highly sialylated isoform of the neural cell adhesion molecule is a feature common to cell capable of migration and conformation changes. 11,18,19 Polysialylated neural cell adhesion molecule also intervenes in axonal outgrowth and synaptogenesis during development and after lesion. 11,13 High levels of polysialylated neural cell adhesion molecule immunoreactivity are normally visible in laminae I,II and X of the adult rat spinal cord. 2,15 We how here that unilateral cervical dorsal rhizotomy induced no detectable changes in immunoreactivity in these areas. However, 24 h after lesion, polysialylated neural cell adhesion molecule immunoreactivity appeared in neurons scattered in laminae III-IX, ipsi-and contralateral to lesion. This reaction increased particularly on the contralateral side, became maximal at four days and disappeared eight days later. At this time, there was immunolabelling of astrocytes with an activated morphology. The astrocytic labelling, predominant on the side ipsilateral to the lesion, was strongest 12 days after rhizotomy, then diminished progressively. Deafferentation thus causes a transient expression of polysialylated neural cell adhesion molecule within areas of the spinal cord distinct from those which permanently express this adhesion molecule. Such expression occurs both in neurons and glial cells, with a temporal pattern specific to each type of cell.

Afferent Pathways↗

PubMed1996

Quality improvement in gastrointestinal endoscopy: microbiologic surveillance of disinfection.

BACKGROUND: Cleaning and disinfection procedures play an essential role in the prevention of infection transmission in gastrointestinal endoscopy. In spite of published detailed guidelines, several variants and weak points still exist. METHODS: Cleaning-disinfection procedures were carried out according to "Working Party, Sydney 1990." A microbiologic surveillance protocol tested the contamination of endoscopes and of automatic washing machines. To assess and improve the efficacy of disinfection, we adopted a quality assurance program. RESULTS: During a 2-year follow-up, the outside surfaces of gastroscopes were contaminated in 60.5% and channels in 41.3%; the outside areas of colonoscopes were contaminated in 62.3% and channels in 40.3%. Isolated bacteria were gram-negative organisms, particularly Pseudomonas species, and gram-positive organisms, mostly Staphylococcus species. The water reservoirs of automatic washing machines were frequently contaminated by Pseudomonas aeruginosa. The disinfection of washing machines and alcohol rinsing of endoscopes after standard procedures significantly reduced the bacterial contamination. CONCLUSIONS: The microbiologic surveillance pointed out the main weak points that could be improved by the adoption of corrective interventions. Quality assurance is a feasible method to assess the efficacy of cleaning-disinfection, and its wide application would improve quality of care.

Colony Count, Microbial↗

PubMed1996

High effectiveness and safety of one-week antibiotic regimen in Helicobacter pylori eradication.

BACKGROUND: Helicobacter pylori is strongly associated with peptic ulcer: H. pylori eradication markedly decreases the recurrence rate of duodenal and gastric ulcer, but the optimum length of antibiotic therapy in the eradication of H. pylori is still unclear. AIM: To verify the effectiveness and side-effect profile of an eradicating regimen consisting of omeprazole 20 mg daily for 4 weeks and, during the first week, combination antimicrobial treatment with tinidazole 500 mg b.d. plus clarithromycin 250 mg b.d. in patients with active duodenal and gastric ulcer. METHODS: One hundred and ninety-six duodenal ulcer patients and 27 gastric ulcer patients with H. pylori infection were admitted into an open prospective study. Compliance was assessed by an accurate interview. RESULTS: Overall, H. pylori was successfully eradicated in 201 of 223 patients (intention-to-treat 90.1%; 95% CI = 85-94%): 176 of 196 duodenal ulcer patients became H. pylori-negative (89.8%; CI = 85-94%) as well as 25 of 27 gastric ulcer patients (92.6%; CI = 76-99%). Compliance was excellent in 221 of 223 (99.1%) patients evaluated as having taken all the medication as prescribed. Sixteen patients (7.2%) developed mild side effects during treatment. CONCLUSION: This combination treatment had excellent results with almost absolute compliance and a very low rate of minor side effects.

Adult↗

PubMed1996

Identification of subjects at risk for colorectal carcinoma through a test based on K-ras determination in the stool.

BACKGROUND & AIMS: The gold standard for screening for colorectal carcinoma is colonoscopy. The aim of this study was to compare endoscopic results with those obtained using the noninvasive screening test of K-ras determination in the stool in a large population of patients undergoing colonoscopy. METHODS: Two hundred thirty consecutive patients were studied by K-ras amplification on stool-derived DNA using polymerase chain reaction and oligomer-specific hybridization. RESULTS: Wild-type K-ras was amplified in 103 of 230 patients (44.8%), the rate of amplification being directly proportional to the presence of an organic disease of the intestine characterized by hyperproliferating mucosa. In 30 of these 103 patients (29.1%), a K-ras mutation was found. Four of 5 with early colorectal carcinoma, all who had K-ras mutations in the tumor, were identified. In first-degree relatives of patients with colorectal carcinoma, all subjects either carrying adenomas > 1 cm in diameter or multiple smaller adenomas were identified. In patients with inflammatory bowel disease, the test identified the only patient with neoplastic transformation. CONCLUSIONS: The sensitivity and specificity of K-ras determination on stool-derived DNA in patients with colorectal carcinoma, in first-degree relatives of patients with colorectal carcinoma, and in patients with inflammatory bowel disease support the opportunity of a large-scale trial to validate its use as a screening test.

Adenoma↗

PubMed1996

Brush cytology: a reliable method to detect Helicobacter pylori.

This study was conducted to verify the reliability of brush cytology in detecting Helicobacter pylori in an unselected group of patients with duodenal ulcer (DU) and nonulcer dyspepsia (NUD). Endoscopy was performed on 416 consecutive patients: group A, 94 with active DU; group B, 176 patients with DU after omeprazole (n = 78), ranitidine (n = 43), or triple anti-H. pylori therapy (n = 55); and group C, 146 patients with NUD. During endoscopy, the gastric mucosa was brushed and two biopsy samples from the antrum and body were obtained for histology. In 65 patients, culture of the brush-collected materials also was performed as was that from of biopsy samples. The overall frequency of H. pylori presence detected by brush cytology was significantly higher compared with that of histology (p < 0.001), particularly in group A (p < 0.05), group C (p < 0.05), and in patients with DU after omeprazole treatment (p < 0.01), but not in patients with DU after ranitidine or anti-H. pylori treatment. The overall frequency of H. pylori-positive cultures from the brush-collected material was higher compared with cultures from the biopsy samples (38.5% vs. 24.6%), particularly in the NUD group (32.6% vs. 16.3%). Brush cytology is more sensitive than histology, besides being faster and cheaper, for the assessment of H. pylori infection, particularly when the density of the bacteria is low.

Adolescent↗

PubMed1995

Variant estrogen receptor messenger RNA species detected in human primary hepatocellular carcinoma.

The development of hepatocellular carcinoma (HCC) in addition to cirrhosis affects males in a significantly higher proportion than females. Liver estrogen receptors increase when HCC develops in males; however, these tumors usually respond poorly to antiestrogens. We have, therefore, hypothesized that, similar to breast cancer, estrogen receptors in males with HCC may be mutated. Variant estrogen receptor transcripts (lacking exon 5 of the hormone binding domain) were investigated by reverse transcription-PCR in 14 patients (7 males and 7 females) with HCC. While females mostly displayed the wild-type transcript (both in peritumoral and in tumor liver tissue), males showed both transcripts in the cirrhotic tissue and almost only the variant in the tumor. As the variant ER transcripts when translated could give rise to truncated receptors still able to constitutively activate transcription, they may be key factors in favoring deregulated proliferation in the male liver.

Blotting, Northern↗

PubMed1995

Selection of more pathogenic hepatitis C virus genotype II during long-term follow-up of interferon-treated patients.

The behavior of hepatitis C virus (HCV) infection with regards to type and number of HCV genotypes (tested with genotype-specific nested polymerase chain reaction) was evaluated in 60 patients with anti-HCV-positive chronic active hepatitis without cirrhosis [17 untreated and 43 subjects undergoing single or repeat courses of interferon (IFN) therapy] during a mean follow-up period of 76 +/- 18 months. In untreated patients (2 genotype I, 6 genotype II, 9 mixed infections) 4 out of 9 mixed infections selected for genotype II at the end of follow-up. Of the 43 treated patients 10 were long-term responders with histological remission, 6 were short-term responders, and 22 did not respond. Fifteen of the latter patients received another course of IFN therapy, and only 3 patients responded. Eight of the 10 responders had infection with a single genotype (4 gt I, 3 gt II, 3 gt III). After IFN therapy, all but 2 patients cleared the HCV infection. The responders to the second IFN course (1 gt I, 1 gt II, 1 gt III) remained viremic. Of the short-term responders, 2/6 patients had genotype II and 4 had a mixed infection (3 gt II +/- I and 1 gt II +/- III); gt III became prevalent in the latter in all but one patient. Of the nonresponders 18/24 had more than one genotype, 5 were genotype II at baseline and one had genotype I. At the end of the follow-up period 15/18 with mixed infection had selected for gt II (P < 0.01 vs. untreated patient).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1995

Evidence for hepatitis B virus infection in patients with chronic hepatitis C with and without serological markers of hepatitis B.

To assess the influence of HBV infection on anti-HCV-positive chronic liver disease, we performed a prospective case-control study comparing 19 HBsAg-positive, anti-HCV-positive patients with 38 HBsAg-negative, anti-HCV-positive patients, pair-matched for age, sex, and ALT levels. HBV and HCV infections were investigated by standard serology and polymerase chain reaction. HCV RNA was found in all patients with CAH and in 90.0% with cirrhosis (33% HBsAg-positive). HBV DNA sequences were found, in the HBsAg-positive subjects, in 71.4% of CAH and in 83.3% of cirrhotics; in the HBsAg-negative ones, only 10% of CAH but 77.7% of cirrhotics had demonstrable HBV DNA sequences. Consequently, 80.0% of cirrhotics had evidence of both HBV and HCV infection. Conventional serology gives partial information on the true occurrence of HBV infection in HBsAg-negative patients, while PCR defines more accurately the HBV status. When the rate of double infection is defined in this way, it correlates with the presence of cirrhosis.

Case-Control Studies↗

PubMed1995

Cell proliferation in the post-natal and adult mammalian central nervous system.

In the mammalian central nervous system cell proliferation is generally linked to developmental processes that are ultimated in the perinatal period. Few exceptions to this rule are known in certain regions of the mammalian brain, namely the post-natal cerebellar cortex and the adult subependymal layer. We report here the results of our studies about cell proliferation and related phenomena in these regions. Cell proliferation was visualised after bromodeoxyuridine incorporation and labeling of the proliferating cell nuclear antigen (PCNA), an endogenous protein expressed during the cell cycle. The occurrence of programmed cell death in the post-natal cerebellar cortex and the persistence of the embryonic isoform of neural cell adhesion molecule (NCAM) associated with proliferating cells in the adult subependymal layer were also investigated.

Animals↗

PubMed1995

Long-term follow-up of hepatitis C virus (HCV) infection in liver transplant patients.

Chronic hepatitis represents a frequent event after orthotopic liver transplantation (OLT). To ascertain the influence of HCV infection on the clinical and histological outcome of these patients, we have investigated the long-term outcome of 22 patients with end-stage chronic liver disease undergoing liver transplant focusing the attention on the role of different HCV genotypes in determining recurrence and severity of post-OLT liver disease. For all patients blood samples taken before OLT and 3 months, 1, 2 and 3 years after OLT were tested for antiHCV antibodies by two different enzyme-linked immuno-assays and by recombinant immuno-blot II and for the presence and type of HCV RNA by nested PCR (5' untranslated region and core gene primers). Of the 16 pre-OLT antiHCV-positive patients, 14 (87.5%) had recurrence of HCV infection while 2 cleared HCV. Pre-OLT genotype recurred in 11 of these 14 patients (2 genotype I) 8 genotype II - in 1 case associated with genotype III - and 1 genotype IV). Of the 6 pre-OLT antiHCV-negative patients, only 1 (16.6%) became persistently HCV-infected, with genotypes I and II. The recurrence of genotype II strictly related with development of severe chronic hepatitis while genotype I and IV were associated with milder forms of liver disease and were more easily cleared.

Chronic Disease↗

PubMed1995

The neurochemical maturation of the rabbit cerebellum.

The immunocytochemical distribution of several neuronal and glial antigens was investigated in the cerebellum of the developing and adult rabbit. Neurofilament positive neurons appeared at embryonic day (E) 25. Purkinje cells transiently expressed neurofilament polypeptides from postnatal day (P) 0 to 15. At later postnatal ages, staining was localised to the parallel fibres, the axonal arbors of the basket cells and fibres of the white matter. Neuron specific enolase (NSE) immunoreactivity was first detected at E25. At P0 Purkinje cells were positive and their staining intensity increased up to P25. From P30 to adulthood virtually all cells in the molecular and Purkinje cell layers were stained. Scattered PGP 9.5-immunoreactive neurons appeared in the cerebellar anlage at P25. Purkinje and Golgi cells were labelled by P0. Synaptophysin immunoreactivity was first observed at P0 in the form of a fine punctate reaction surrounding the perikarya and proximal dendrites of Purkinje cells. By P10, it became particularly intense within the cerebellar glomeruli of the granular layer. Neurons of the deep cerebellar nuclei expressed NSE and PGP 9.5 starting from E25. GFAP and S-100 immunoreactivities were first detected at P10. GFAP-immunopositive astrocytes progressively increased in number up to adulthood. S-100-immunoreactive glial cells were detected throughout the white and grey matter. Bergmann glial cells and their fibres were strongly immunoreactive. Vimentin positive glial cells and fibres were first observed at E15 and persisted up to adulthood. Double labelling experiments using a monoclonal antibody against the proliferating cell nuclear antigen (PCNA), a cyclin synthesised by mitotic cells, showed that neuronal and/or glial polypeptides are expressed only by fully differentiated postmitotic cells. These results indicate that major events in the neurochemical maturation of the rabbit cerebellum occur during the first month after birth, when the same pattern of the adult animal is attained.

Animals↗

PubMed1994

Insulin receptor substrate-1 (IRS-1) distribution in the rat central nervous system.

Insulin receptor substrate 1 (IRS-1) is the primary cytosolic substrate of the insulin and insulin-like growth factor-I (IGF-I) receptors. Following tyrosine phosphorylation IRS-1 binds to and activates specific proteins containing SH2 domains. Using biochemical and immunocytochemical techniques, we have mapped the distribution of IRS-1 in the CNS of the adult rat and compared it with that of insulin and IGF-I receptors and phosphatidylinositol 3-kinase (PI-3 kinase), a signaling molecule functionally related to IRS-1. Immunoprecipitation and Western blotting experiments demonstrate the presence of substantial amounts of IRS-1, insulin receptor, and PI-3 kinase in the brain. IRS-1 immunoreactivity is widely distributed in neurons from several areas of the brain and spinal cord. The cerebral cortex, the hippocampus, many hypothalamic and thalamic nuclei, the basal ganglia, the cerebellar cortex, the brainstem nuclei, and the lamina X of the spinal cord are particularly rich of immunopositive nerve cells. In these areas most of the neurons immunoreactive for IRS-1 are also stained by either anti-insulin receptor or anti-IGF-I receptor antibodies as well as PI-3 kinase antiserum. IRS-1 immunostaining was very weak or totally absent in neurons of the olfactory bulb, the supraoptic and paraventricular nuclei, the mesencephalic trigeminal nucleus, and the granule cell layer of the cerebellum, despite the fact that these areas were immunolabeled with antibodies against insulin or IGF-I receptors and/or PI-3 kinase. These results show that neurons in the adult rat CNS are endowed with some of the components of the early signaling pathway for growth factors of the insulin/IGF-I family, although IRS-1 has a distribution distinct from that of the two receptors.

Animals↗