Biomedical subjects

M Marino

Publications and source records attributed to M Marino.

At least 55 records · Page 3Linked to original sources

PubMed2001

Confocal microscopy analysis of the activity of mitochondria contained within the 'mitochondrial cloud' during oogenesis in Xenopus laevis.

We have used ratiometric confocal microscopy and three fluorescence techniques to study the distribution and activity of mitochondria in frog oocytes during the early stages of oogenesis. Mitochondria in frog oocytes during oogenesis were characterised by a high ratio in the 'mitochondrial cloud' and perinuclear region and a low ratio in mitochondria freely dispersed within the cytoplasm. We tested whether the high ratio visualised by the three techniques represented mitochondrial membrane potential by perturbing the mitochondrial membrane potential. Carbonyl cyanide p-(trifluoromethyl)phenylhydrazone (FCCP) caused the immediate destruction of the membrane potential, and consequent loss of fluorescence from the membrane-potential-sensitive confocal channel. In contrast, nigericin caused an increase in membrane potential represented by a steady increase in fluorescence ratio. These data demonstrate that mitochondrial activity can be measured during oogenesis in frog oocytes, and suggest that the mitochondrial cloud and perinuclear regions are characterised by highly active mitochondria.

Animals↗

PubMed2001

Increased risk of surgery in undiagnosed celiac disease.

The diagnosis of celiac disease patients may be delayed by misdiagnosis. Our aim was to evaluate in celiac patients the prevalence of surgery before diagnosis. Two hundred forty-four adult celiac patients and 232 controls were retrospectively investigated for surgery before diagnosis of celiac disease. The prevalence of surgery was increased in celiac patients versus controls (P = 0.001). Frequency of appendectomy (P = 0.0001), tonsillectomy (P = 0.009), and hernia repair (P = 0.05) were increased in celiac patients versus controls. Appendectomy was related to anemia (P = 0.006) and abdominal pain (P = 0.005); tonsillectomy was related to diarrhea (P = 0.02) and weight loss (P = 0,04). Appendectomy was elective in 73% of celiac patients and in 46% of controls. Cosmetic surgery was increased in celiac patients versus controls (P = 0.058). In conclusions, surgery before celiac disease diagnosis is increased in celiac patients compared to controls, as a result of doctors' misdiagnosis and/or poor health status, which increases the demand for medical intervention. The frequency of cosmetic surgery in celiac patients may berelated to impaired psychological profile of patients.

Adult↗

PubMed2001

TNF alpha promotes proliferation of oligodendrocyte progenitors and remyelination.

Here we used mice lacking tumor necrosis factor-alpha (TNF alpha) and its associated receptors to study a model of demyelination and remyelination in which these events could be carefully controlled using a toxin, cuprizone. Unexpectedly, the lack of TNF alpha led to a significant delay in remyelination as assessed by histology, immunohistochemistry for myelin proteins and electron microscopy coupled with morphometric analysis. Failure of repair correlated with a reduction in the pool of proliferating oligodendrocyte progenitors (bromodeoxyuridine-labeled NG2(+) cells) followed by a reduction in the number of mature oligodendrocytes. Analysis of mice lacking TNF receptor 1 (TNFR1) or TNFR2 indicated that TNFR2, not TNFR1, is critical to oligodendrocyte regeneration. This unexpected reparative role for TNF alpha in the CNS is important for understanding oligodendrocyte regeneration/proliferation, nerve remyelination and the design of new therapeutics for demyelinating diseases.

Animals↗

PubMed2001

Mitochondrial aggregation patterns and activity in human oocytes and preimplantation embryos.

Mitochondria play a vital role in the metabolism of energy-containing compounds in the oocyte cytoplasm to provide adenosine trisphosphate for fertilization and preimplantation embryo development. In this study, ratiometric confocal microscopy with the mitochondrion-specific membrane potential-sensitive fluorescence dye JC-1 (5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolyl-carbocyanine iodide) was used to measure the activity of mitochondria in human oocytes and developing preimplantation embryos. Mitochondria in oocytes and embryos were characterized by distinct localized aggregation patterns. These patterns however did not determine localized regions of heterogeneity in mitochondrial activity. Mitochondrial activity was analysed during oocyte maturation and after fertilization. The activity of mitochondria in fresh metaphase II oocytes was negatively correlated with maternal age. This trend continued when the activity of developing embryos was analysed. Mitochondrial activity was strongly correlated with the rate of embryo development on day 3 after fertilization, but not on day 2. Partial regression analysis showed that the rate of cleavage of preimplantation embryos was more highly correlated with embryo mitochondrial activity than maternal age. These data suggest that the efficiency of mitochondrial respiration in oocytes and preimplantation embryos is closely correlated with the programmed rate of embryo development, and suggest that maternal age further influences this factor. The loss of mitochondrial activity in oocytes obtained from ageing couples may therefore contribute to lower embryo development and pregnancy rates observed during cycles of IVF.

Benzimidazoles↗

PubMed2001

Pregnancy after cytoplasmic transfer in a couple suffering from idiopathic infertility: case report.

Couples suffering from idiopathic infertility are among the most difficult to treat in IVF cycles due to the unknown cause of failure to reproduce. This can lead to years of unsuccessful attempts to conceive and often the abandonment of treatment. In some couples, the only observable problem is the development of poor quality embryos. In this case report, we describe the successful use of cytoplasmic donation in a couple where the high level of embryo fragmentation and poor embryo development was thought to be the unique cause of failure to conceive after intracytoplasmic sperm injection (ICSI). We noted a strong reduction in embryo fragmentation and a consequent increase in embryo quality after the treatment. Transfer of four of the embryos receiving donor cytoplasm led to a pregnancy with two gestational sacs and the birth of healthy twins.

Adult↗

PubMed2001

Activation of IP(3)-protein kinase C-alpha signal transduction pathway precedes the changes of plasma cholesterol, hepatic lipid metabolism and induction of low-density lipoprotein receptor expression in 17-beta-oestradiol-treated rats.

The intracellular concentration of cholesterol is regulated by the balance between endogenous synthesis and exogenous uptake. Oestrogens have been reported to be involved in the physiological regulation of cellular cholesterol content. Relevant reports have focused on long-term responses and there is a lack of information about the relationship between the timing of the oestrogen effect and the regulation of cholesterol homeostasis. The aim of this work has been to set up a systematic picture of the short-term effects induced by oestrogen on hepatic lipid metabolism in vivo and the involvement of some relevant signal transduction pathways. At intervals after oestrogen administration (30 min to 6 h), oestrogen receptor expression and changes in liver cAMP, IP(3) and protein kinase C-alpha (PKC-alpha) were followed. Changes in the expression of the low density lipoprotein receptor at mRNA and protein levels, and of hydroxy-methyl-glutaryl-CoA reductase activity have been verified. At the same time, the content of hepatic cholesterol, ubiquinone and dolichol and of plasma cholesterol have been determined. Changes of rab 5 and rab 8, small GTP-binding prenylated proteins involved in the transfer of neosynthesised proteins through the cell, have been also checked. In vivo treatment with oestradiol produced no change in cyclic AMP but a rapid increase in IP(3), increased PKC-alpha localisation on the membranes and enhanced expression of the low density lipoprotein receptor in the liver occurred. PKC inhibition completely prevented any increase in low density lipoprotein receptor mRNA in isolated and perfused rat liver. Early changes of ubiquinone and dolichol content and a later reduction in hepatic hydroxy-methyl-glutaryl-CoA reductase activity and plasma cholesterol content were also detectable. A functional role of the IP(3) -protein kinase C-alpha pathway in the induction of the low density lipoprotein receptor is suggested. Experimental Physiology (2001) 86.1, 39-45.

Animals↗

PubMed2001

Modulation of anaerobic energy metabolism of Bacillus subtilis by arfM (ywiD).

Bacillus subtilis grows under anaerobic conditions utilizing nitrate ammonification and various fermentative processes. The two-component regulatory system ResDE and the redox regulator Fnr are the currently known parts of the regulatory system for anaerobic adaptation. Mutation of the open reading frame ywiD located upstream of the respiratory nitrate reductase operon narGHJI resulted in elimination of the contribution of nitrite dissimilation to anaerobic nitrate respiratory growth. Significantly reduced nitrite reductase (NasDE) activity was detected, while respiratory nitrate reductase activity was unchanged. Anaerobic induction of nasDE expression was found to be significantly dependent on intact ywiD, while anaerobic narGHJI expression was ywiD independent. Anaerobic transcription of hmp, encoding a flavohemoglobin-like protein, and of the fermentative operons lctEP and alsSD, responsible for lactate and acetoin formation, was partially dependent on ywiD. Expression of pta, encoding phosphotransacetylase involved in fermentative acetate formation, was not influenced by ywiD. Transcription of the ywiD gene was anaerobically induced by the redox regulator Fnr via the conserved Fnr-box (TGTGA-6N-TCACT) centered 40.5 bp upstream of the transcriptional start site. Anaerobic induction of ywiD by resDE was found to be indirect via resDE-dependent activation of fnr. The ywiD gene is subject to autorepression and nitrite repression. These results suggest a ResDE --> Fnr --> YwiD regulatory cascade for the modulation of genes involved in the anaerobic metabolism of B. subtilis. Therefore, ywiD was renamed arfM for anaerobic respiration and fermentation modulator.

Anaerobiosis↗

PubMed2000

A framework for interpreting the leucine-rich repeats of the Listeria internalins.

The surface protein InlB of the bacterial pathogen Listeria monocytogenes is required for inducing phagocytosis in various nonphagocytic mammalian cell types in vitro. InlB causes tyrosine phosphorylation of host cell adaptor proteins, activation of phosphoinositide 3-kinase, and rearrangements of the actin cytoskeleton. These events lead to phagocytic uptake of the bacterium by the host cell. InlB belongs to the internalin family of Listeria proteins, which also includes InlA, another surface protein involved in host cell invasion. The internalins are the largest class of bacterial proteins containing leucine-rich repeats (LRR), a motif associated with protein-protein interactions. The LRR motif is found in a functionally diverse array of proteins, including those involved in the plant immune system and in the mammalian innate immune response. Structural and functional interpretations of the sequences of internalin family members are presented in light of the recently determined x-ray crystal structure of the InlB LRR domain.

Amino Acid Sequence↗

PubMed2000

Interaction of cell cycle kinases, microtubules, and chromatin in ascidian oocytes during meiosis.

We used kinase assays and confocal microscopy to study the interaction of cell cycle proteins with microtubule organising centres (MTOC) and chromatin in ascidian oocytes during meiosis. The activity of maturation promoting factor (MPF) and mitogen activated protein kinase (MAPK) appear not to be correlated in control oocytes. MPF activity peaks during metaphase I and II of the meiotic cell cycle whereas the activity of MAPK peaks at telophase I and is subsequently degraded to remain at low levels for the remainder of meiosis. The protein synthesis inhibitor emetine induces the degradation in MPF activity in unfertilized metaphase-I (M-I) oocytes, while MAPK is unaffected. Emetine does not alter the activities of these cell cycle kinases in fertilized oocytes during meiosis I but MPF activity remains low while MAPK activity is high for an elongated time period and oocytes do not complete meiosis I. Emetine induces maternal MTOC duplication in unfertilized M-I oocytes and prevents sperm aster growth in fertilized oocytes, but it does not alter the M-I meiotic apparatus in unfertilized oocytes. These experiments suggest that neither MPF alone nor emetine-sensitive proteins are responsible for M-I arrest in ascidian oocytes, MAPK may ensure this stability. In addition, we showed that the maternal MTOC is present at M-I but suppressed from duplicating in an emetine-sensitive manner.

Animals↗

PubMed2000

Reduction pneumoplasty versus respiratory rehabilitation in severe emphysema: a randomized study. Pulmonary Emphysema Research Group.

BACKGROUND: The purpose of the study was to determine in a prospective randomized trial the independent short-term physiologic impact of reduction pneumoplasty (RP) on respiratory rehabilitation (RR). METHODS: Sixty patients eligible for RP were randomly selected by computer to receive either RP (n = 30) or comprehensive RR (n = 30). Pulmonary function tests, analysis of blood gas levels, measurement of respiratory muscle strength (maximal inspiratory and expiratory pressures), 6-minute walk test (6MWT), and incremental treadmill test (ITT), were performed at baseline and at 3 and 6 months. RESULTS: Two treatment-related deaths occurred after RP and one after RR. At 6 months dyspnea index, maximal inspiratory pressure, 6MWT, ITT, and PaO2 were significantly improved in both groups whereas forced expiratory volume in 1 second and residual volume were significantly improved only in the surgical arm. In addition at 6 months, dyspnea index, 6MWT, maximal ITT, and PaO2 improved significantly more after RP than after RR. CONCLUSIONS: In our study short-term improvements in dyspnea index, oxygenation, inspiratory muscle strength, and exercise capacity occurred after either RP and RR. However dyspnea index, PaO2, and exercise capacity improved more after RP than after RR whereas pulmonary function improved only after RP.

Aged↗

PubMed2000

Regional lung deposition of a technetium 99m-labeled formulation of mometasone furoate administered by hydrofluoroalkane 227 metered-dose inhaler.

BACKGROUND: A new inhaled suspension formulation of mometasone furoate (MF), a potent corticosteroid with minimal systemic availability, has been developed for the treatment of asthma. This formulation is delivered by metered-dose inhaler (MDI) using the nonchlorofluorocarbon propellant hydrofluoroalkane 227 (HFA-227). OBJECTIVE: The primary goal of this study was to determine the respiratory tract deposition of this formulation of MF. A secondary objective was to measure plasma concentrations of MF and a putative metabolite, 6-X-OH MF, to determine the systemic exposure to corticosteroid. METHODS: This was a single-dose, open-label study in which 200 microg of technetium 99m (99mTc)-radiolabeled MF was administered to patients with asthma. Gamma scintigraphy was used to quantify lung, oropharyngeal, stomach, and MDI mouthpiece deposition patterns of MF. RESULTS: Eleven patients, aged 21 to 47 years, with a history of asthma were enrolled in and completed the study. The mean (+/- SD) whole lung deposition of MF was 13.9%+/-5.7% of the metered (ex-valve) dose. The central lung zone received 5.3%+/-2.8% of the dose; the intermediate zone received 4.7%+/-1.9%; and peripheral lung deposition was 4.0%+/-1.5%. The mean (+/- SD) ratio of peripheral to central lung deposition was 0.8+/-0.2. Oropharyngeal deposition was 79.1%+/-8.7% of the ex-valve dose, with 6.3%+/-7.8% deposited on the MDI mouthpiece and 0.7%+/-0.5% exhaled. The majority of plasma samples taken for analysis of MF and 6-13-OH MF concentrations were below the limit of quantification (50 pg/mL) in all patients after inhalation of 200 microg 99mTc-labeled ME CONCLUSION: The lung deposition of MF when administered via HFA-227 MDI is comparable to the 10 to 20% lung deposition seen with other corticosteroid suspension for- mulations administered by MDI that have demonstrated effectiveness in the treatment of asthma.

Administration, Inhalation↗

PubMed2000

Prevention of experimental autoimmune encephalomyelitis by encephalitogenic epitope sequence simplified derivatives.

The encephalitogenic epitope P81-100 from mouse myelin basic protein was used to generate two simplified derivatives with glycine substitutions in alternating positions which were tested for their biological activity in a murine model of multiple sclerosis, experimental autoimmune encephalomyelitis. While both derivatives were unable to induce in mice the disease at the same parent peptide P81-100 dosage, T cell proliferation assays demonstrated their ability to compete with the parental peptide in a dose related manner. Experiments of cell surface binding and T cell tolerance revealed a different behavior of the two derivatives, suggesting different roles in the MHC blockade or T cell tolerance. On induction of encephalomyelitis in animals by P81-100 treatment, one variant proved in vivo to be very effective in protecting from the disease.

Animals↗

PubMed2000

Meiosis-associated calcium waves in ascidian oocytes are correlated with the position of the male centrosome.

We have used confocal microscopy to measure calcium waves and examine the distribution of tubulin in oocytes of the ascidian Ciona intestinalis during meiosis. We show that the fertilisation calcium wave in these oocytes originates in the vegetal pole. The sperm penetration site and female meiotic apparatus are found at opposite poles of the oocyte at fertilisation, confirming that C. intestinalis sperm enter in the vegetal pole of the oocyte. Following fertilisation, ascidian oocytes are characterised by repetitive calcium waves. Meiosis I-associated waves originate at the vegetal pole of the oocyte, and travel towards the animal pole. In contrast, the calcium waves during meiosis II initiate at the oocyte equator, and cross the oocyte cytoplasm perpendicular to the point of emission of the polar body. Immunolocalisation of tubulin during meiosis II reveals that the male centrosome is also located between animal and vegetal poles prior to initiation of the meiosis II-associated calcium waves, suggesting that the male centrosome influences the origin of these calcium transients. Ascidians are also characterised by an increase in sensitivity to intracellular calcium release after fertilisation. We show that this is not simply an effect of oocyte activation. The data strongly suggest a role for the male centrosome in controlling the mechanism and localisation of post-fertilisation intracellular calcium waves.

Animals↗

PubMed2000

Prevention of systemic lupus erythematosus in MRL/lpr mice by administration of an immunoglobulin-binding peptide.

Systemic lupus erythematosus (SLE) is a multisystem chronic inflammatory disease of unknown etiology that affects many organs, including the kidney. The presence of multiple autoantibodies and other immunological abnormalities point to basic defects in immunoregulatory controls that normally maintain self-tolerance. The deposition on kidney tissue of autoantibodies as immune complexes (ICs) through the interaction with Fc-receptor gamma-chains is thought to trigger an inflammatory response typical of SLE, leading to glomerulonephritis. Using combinatorial chemistry approaches, we have identified a peptide able to bind to immunoglobulins and to interfere with Fcgamma-receptor recognition. Administration of this peptide to MRL/lpr mice, an animal model used to study SLE, resulted in a remarkable enhancement of the survival rate (80%) compared to placebo-treated animals (10%). Consistent with this was a significant reduction of proteinuria, a clinical sign of SLE. Kidney histological examination of treated animals confirmed the preservation of tissue integrity and a remarkable reduction in IC deposition. These results support the role of Fcgamma receptors in SLE pathogenesis and open new avenues for the development of drugs to treat autoimmune disorders.

Age Factors↗

PubMed2000

Population PK and PK/PD modelling of microencapsulated octreotide acetate in healthy subjects.

AIMS: To develop a population model that can describe the pharmacokinetic profile of microencapsulated octreotide acetate in healthy cholecystectomized subjects. To investigate the correlation between serum IGF-1 and octreotide concentration. METHODS: A population pharmacokinetic analysis was performed on octreotide data obtained following a single dose of 30 mg microencapsulated octreotide acetate intramuscularly. The relationship between serum IGF-1 concentration and octreotide concentration was effectively described by a population pharmacokinetic/pharmacodynamic model. RESULTS: The pharmacokinetic profile of octreotide was characterized by an initial peak of octreotide followed by a sustained-release of drug. Plateau concentration were sustained up to day 70, and gradually declined to below the detection limit by day 112. A one-compartment linear model was constructed which consisted of two absorption processes, characterized by KIR and KSR, rate constants for immediate-release and sustained-release, respectively, with first-order elimination (Ke; 1.05 h-1). The surface, unencapsulated drug was immediately absorbed into the central compartment with first-order absorption (KIR; 0.0312 h-1), while the microencapsulated drug was first released in a zero-order fashion into a depot before being absorbed into the central compartment with first-order absorption (KSR; 0.00469 h-1) during a period of tau (1680 h). Body weight and gender were important covariates for the apparent volume of distribution. The type of formulation was an important covariate for KIR but had no effect on KSR. An inhibitory Emax population pharmacokinetic/pharmacodynamic model could adequately describe the relationship between IGF-1 (expressed as percent baseline) and octreotide concentration. Baseline IGF-1 concentration was found to be a significant covariate for the baseline effect (E0). A relationship between GH concentration and octreotide concentration was not established. CONCLUSIONS: The pharmacokinetic profile of microencapsulated octreotide acetate was effectively described by the derived population model. The relationship between IGF-1 and drug concentration could be used to guide optimization of therapeutic octreotide dosage regimens.

Adult↗

PubMed2000

The capacity of Enterobacteriaceae species to produce biogenic amines in cheese.

The amino acid decarboxylating activity and production of biogenic amines by 104 cheese-associated Enterobacteriaceae species (58 Enterobacter, 18 Serratia, eight Escherichia, seven Hafnia, six Arizona, four Citrobacter and three Klebsiella) were investigated. All strains could decarboxylate at least two amino acids in Möller's broth and in Niven's medium, and the decarboxylase activity was strain specific. In a laboratory medium containing all free amino acids, all strains could produce more than 100 ppm cadaverine, putrescine was produced by 96% of strains. Tyramine and histamine were produced in the lowest concentrations. A positive correlation existed between cadaverine concentration and Enterobacteriaceae counts in cheese, that may have caused the increase in decarboxylase content. This study suggests that it is possible to limit the presence of cadaverine in cheese, thereby controlling the Enterobacteriaceae counts, a sign of contamination during cheese making and/or storage.

Biogenic Amines↗

PubMed2000

Epidermal growth factor regulates amino acid transport in chick embryo hepatocytes via protein kinase C.

System A-mediated amino acid transport, activation of different steps of signal transduction and involvement of different isoforms of protein kinase C (PKC) have been investigated in chick embryo hepatocytes after epidermal growth factor (EGF) stimulation. EGF rapidly (10 min) increased the rate of aminoisobutyric acid (AIB) uptake in chick embryo hepatocytes freshly isolated on the 19th day of embryonic life, while no change was detectable at other embryonal stages. The growth factor stimulation was abolished by PKC and tyrosine kinase inhibitors and was mimicked by 4-phorbol-12-myristate-13-acetate, dimethyl-2 (PMA). EGF treatment did not modify the phosphorylation of the isoform of phospholipase C (PLC-), and inositol trisphosphate (IP3) and intracellular calcium levels, but it induced an increase in PKC activity. Our data show that EGF regulates amino acid uptake, via PKC and without PLC- activation, only in the last period of chick embryo hepatocyte development. The effects of growth factor on PKC activity suggest the involvement of PKC- and - isoforms in EGF modulation of amino acid transport.

Amino Acids↗

PubMed2000

Fermentative metabolism of Bacillus subtilis: physiology and regulation of gene expression.

Bacillus subtilis grows in the absence of oxygen using nitrate ammonification and various fermentation processes. Lactate, acetate, and 2,3-butanediol were identified in the growth medium as the major anaerobic fermentation products by using high-performance liquid chromatography. Lactate formation was found to be dependent on the lctEP locus, encoding lactate dehydrogenase and a putative lactate permease. Mutation of lctE results in drastically reduced anaerobic growth independent of the presence of alternative electron acceptors, indicating the importance of NADH reoxidation by lactate dehydrogenase for the overall anaerobic energy metabolism. Anaerobic formation of 2,3-butanediol via acetoin involves acetolactate synthase and decarboxylase encoded by the alsSD operon. Mutation of alsSD has no significant effect on anaerobic growth. Anaerobic acetate synthesis from acetyl coenzyme A requires phosphotransacetylase encoded by pta. Similar to the case for lctEP, mutation of pta significantly reduces anaerobic fermentative and respiratory growth. The expression of both lctEP and alsSD is strongly induced under anaerobic conditions. Anaerobic lctEP and alsSD induction was found to be partially dependent on the gene encoding the redox regulator Fnr. The observed fnr dependence might be the result of Fnr-induced arfM (ywiD) transcription and subsequent lctEP and alsSD activation by the regulator ArfM (YwiD). The two-component regulatory system encoded by resDE is also involved in anaerobic lctEP induction. No direct resDE influence on the redox regulation of alsSD was observed. The alternative electron acceptor nitrate represses anaerobic lctEP and alsSD transcription. Nitrate repression requires resDE- and fnr-dependent expression of narGHJI, encoding respiratory nitrate reductase. The gene alsR, encoding a regulator potentially responding to changes of the intracellular pH and to acetate, is essential for anaerobic lctEP and alsSD expression. In agreement with its known aerobic function, no obvious oxygen- or nitrate-dependent pta regulation was observed. A model for the regulation of the anaerobic fermentation genes in B. subtilis is proposed.

Acetates↗