Biomedical subjects

A Morelli

Publications and source records attributed to A Morelli.

At least 73 records · Page 4Linked to original sources

PubMed2000

Cellular responses to Loa loa experimental infection in mandrills (Mandrillus sphinx) vaccinated with irradiated infective larvae.

In order to shed light on the mechanisms of antifilarial protective immunity, we investigated the course of experimental loaiosis after vaccination in a nonhuman primate host, Mandrillus sphinx. Six vaccinated (V) mandrills received 50 irradiated L3 while six nonvaccinated (NV) received saline solution on days -60, -30 and -15. All animals were challenged with 100 intact L3 (day 0). Parasitological and immunological status were followed for 9 months. Vaccination delayed the appearance and mean peak of microfilaraemia. Five mandrills (Mf-) were never microfilaraemic (one V mandrill) or microfilaraemic on only one occasion (2 V and 2 NV), the other seven having stable microfilaraemia (Mf+). The cytokine response of peripheral blood mononuclear cells to L3 (L3 Ag) was Th2 dominated, while microfilariae (Mf Ag) elicited a Th0-like response. During vaccination, Th2 cytokine production significantly increased in V mandrills against L3 Ag, as well as Mf Ag, whereas Th1 cytokines decreased. On day 60 postinoculation, cellular proliferation was higher in V mandrills in response to L3 and Mf Ags and PHA-L mitogen. At the end of prepatency (on day 130), mandrills with delayed appearance of microfilaraemia exhibited a high, transient IL-2 and IL-4 secretion in response to L3 Ag. Finally, high anti-Mf Th2 cytokine levels characterized Mf-mandrills not only during prepatency, but also (for IL-5) before immunization. However, the presence of a balanced Th1 anti-L3 response during prepatency in the amicrofilaraemic mandrill suggests its importance in protective immunity. Taken together, our data suggest that Th2 cells and also Th1 components of the antifilarial response, especially to larval antigen, may contribute to parasite elimination.

Animals↗

PubMed2000

The P2 purinergic receptors of human dendritic cells: identification and coupling to cytokine release.

We investigated the expression of purinoceptors in human dendritic cells, providing functional, pharmacological, and biochemical evidence that immature and mature cells express P2Y and P2X subtypes, coupled to increase in the intracellular Ca(2+), membrane depolarization, and secretion of inflammatory cytokines. The ATP-activated Ca(2+) change was biphasic, with a fast release from intracellular stores and a delayed influx across the plasma membrane. A prolonged exposure to ATP was toxic to dendritic cells that swelled, lost typical dendrites, became phase lucent, detached from the substrate, and eventually died. These changes were highly suggestive of expression of the cytotoxic receptor P2X(7), as confirmed by ability of dendritic cells to become permeant to membrane impermeant dyes such as Lucifer yellow or ethidium bromide. The P2X(7) receptor ligand 2',3'-(4-benzoylbenzoyl)-ATP was a better agonist then ATP for Ca(2+) increase and plasma membrane depolarization. Oxidized ATP, a covalent blocker of P2X receptors, and the selective P2X(7) antagonist KN-62 inhibited both permeabilization and Ca(2+) changes induced by ATP. The following purinoceptors were expressed by immature and mature dendritic cells: P2Y(1), P2Y(2), P2Y(5), P2Y(11) and P2X(1), P2X(4), P2X(7). Finally, stimulation of LPS-matured cells with ATP triggered release of IL-1 beta and TNF-alpha. Purinoceptors may provide a new avenue to modulation of dendritic cells function.

Adenosine Triphosphate↗

PubMed2000

MEN1 gene mutation analysis in Italian patients with multiple endocrine neoplasia type 1.

Multiple endocrine neoplasia type 1 (MEN 1) is a familial syndrome characterized by parathyroid, enteropancreatic and pituitary tumors. The gene responsible for this syndrome is localized at chromosomal 11q13 region and DNA markers from this region cosegregate with the disease. The recent identification of the MEN1 gene, encoding for a protein termed menin of 610 amino acids, allowed mutational screening to be performed both in affected families and sporadic cases. To date many different heterozygous mutations, spreading across all the encoding sequence, have been identified in MEN 1 patients with no apparent mutational hot spots or genotype-phenotype correlation. To analyze the genetic alterations of the MEN1 gene occurring in Italian patients we performed mutational screening by Denaturant Gradient Gel Electrophoresis followed by sequencing of exons 2-10 of the MEN1 gene in 27 Italian MEN 1 families and in five sporadic cases. We identified 17 different heterozygous mutations in 60% of analyzed cases. Twelve of these mutations are novel. Two mutations each occurred twice in unrelated families but no evidence of genotype-phenotype correlation can be established for these families. The extension of genetic diagnosis to asymptomatic family members allowed the identification of 10 MEN1 mutant gene carriers, one newly described and nine previously detected by linkage analysis with DNA markers from the 11q13 region. Our findings add new information to the diversity of mutations occurring in the MEN1 gene and confirm that the mutational screening of MEN 1 is a useful approach to detect individuals at higher risk of developing MEN 1-associated tumors.

DNA Mutational Analysis↗

PubMed1999

Mouse dendritic cells express the P2X7 purinergic receptor: characterization and possible participation in antigen presentation.

Immune cells express P2 purinoceptors of the P2Y and P2X subtypes. In the present work, we show that three dendritic cell (DC) lines, D2SC/1, CB1, and FSDC, representative of immature DCs, express the P2X7 (formerly P2Z) receptor, as judged from RT-PCR amplification, reactivity to a specific antiserum, and pharmacological and functional evidence. Receptor expression is higher in FSDC cells, a cell line that is functionally more mature than D2SC/1 and CB1. From the wild-type DC population, we selected cell clones lacking the P2X7R (P2X7less). We also used a P2XR blocker, oxidized ATP, to irreversibly inhibit the P2X7R. Ability of P2X7less FSDCs or of oxidized ATP-inhibited FSDCs to stimulate Ag-specific TH lymphocytes was severely decreased although Ag endocytosis was minimally affected. During coculture with TH lymphocytes, wild-type FSDC secreted large amounts of IL-1beta. Release of this cytokine was reduced in P2X7less DCs. These data show that DCs express the P2X7 purinoceptor and suggest a correlation between P2X7R expression and Ag-presenting activity.

Adenosine Triphosphate↗

PubMed1999

Telomerase repeat amplification protocol (TRAP): A new molecular marker for parathyroid carcinoma.

Telomerase results to be active in human germ, stem cells, several malignant cell tumors and in immortalized cell lines. In order to investigate if molecular mechanisms other than Rb gene inactivation can be helpful to diagnose malignancy of parathyroid tumors, we decided to investigate the presence of active telomerase in homogenates from different pathological parathyroid tissues (hyperplastic, adenomatous, carcinomatous, and normal) and primary cell cultures. The TRAP assay was performed to detect this activity in histologically characterized normal, hyperplastic, adenomatous, and carcinomatous human parathyroid tissues, primary cell lines, and one metastatic tissue from parathyroid carcinoma. Only malignant parathyroid glands and the metastatic tissue were TRAP positive. Our findings suggest that telomerase expression could represent an important molecular mechanism underlying the acquisition and progression of an aggressive phenotype of epithelial parathyroid cells and it may help to predict their malignant potential. The TRAP assay is easy to perform and it could become an additional tool to be included in the harmamentarium for the molecular diagnosis of parathyroid carcinoma.

Biomarkers, Tumor↗

PubMed1999

Plasmodium coatneyi: differential clinical and immune responses of two populations of Macaca fascicularis from different origins.

Two species of macaques, including two Macaca fascicularis from the Philippines, two M. fascicularis from Mauritius, and one Macaca mulatta, were experimentally infected with blood stages of Plasmodium coatneyi and followed during their clinical, parasitological, biological, and immunological evolution. Plasma cytokine (TNF-alpha, IL-1beta, IL-6, IFN-gamma) production peaked for all monkeys 11 days after inoculation, concomitantly with peaks of parasitemia. Only the M. fascicularis from the Philippines survived the infection. The main features, which discriminated nonfatal from fatal cases, were the observation in M. fascicularis from the Philippines of a mean CD4+/CD8+ ratio below I and of their ability, as revealed by mitogenic stimulation of whole blood, to produce increasing amounts of IFN-gamma as infection evolved. The contribution of environmental and genetic factors, which may differentiate the three groups of monkeys and therefore explain fatal or nonfatal evolution of the infection among them, is discussed.

Anemia↗

PubMed1999

Gastrointestinal safety of nitric oxide-derived aspirin is related to inhibition of ICE-like cysteine proteases in rats.

BACKGROUND & AIMS: Caspases, a class of cysteine proteases, modulate apoptosis. Nitric oxide (NO)-releasing nonsteroidal anti-inflammatory drugs (NSAIDs) are a new class of NSAID derivatives with reduced gastrointestinal toxicity. The aim of this study was to investigate whether cysteine endoproteases are involved in the pathogenesis of NSAID gastropathy and are target for NO-aspirin (NCX-4016). METHODS: Rats were treated orally with aspirin or equimolar doses of NCX-4016. Caspase activities were measured by fluorometric assay. Apoptosis was quantified by an enzyme-linked immunosorbent assay for histone-associated DNA, DNA ladder on agarose gel, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assay. A primary culture of gastric chief cells was used to investigate whether NCX-4016 modulates guanosine 3',5'-cyclic monophosphate (cGMP)-dependent pathways. RESULTS: Short- and long-term (7 days) aspirin administration resulted in a time- and dose-dependent gastric injury that was associated with apoptosis and caspase up-regulation. Z-VAD.FMK, a pancaspase inhibitor, and NO donors protected from acute damage induced by aspirin. NCX-4016 spared the gastric mucosa and caused caspase inactivation by S-nitrosylation. Inhibition of tumor necrosis factor (TNF)-alpha release or activity by TAPI-2 or anti-TNF-alpha receptor monoclonal antibodies protected against mucosal damage and caspase activation. NCX-4016 protected gastric chief cells from toxicity induced by TNF-alpha by activating cGMP-dependent pathways. CONCLUSIONS: Aspirin administration leads to a TNF-alpha-dependent activation of gastric caspases. NO-aspirin spares the gastric mucosa and inhibits caspase activity through cGMP-dependent and -independent pathways.

Animals↗

PubMed1999

Enhanced anti-inflammatory effects of a nitric oxide-releasing derivative of mesalamine in rats.

BACKGROUND & AIMS: Nitric oxide (NO)-releasing derivatives of cyclooxygenase inhibitors exhibit enhanced anti-inflammatory activity and greatly reduced gastrointestinal toxicity. We evaluated whether a similar derivatization of mesalamine (5-aminosalicylic acid) would improve its anti-inflammatory activity. METHODS: Effects of an NO-releasing derivative of mesalamine (NCX-456; NO-mesalamine) were compared with those of mesalamine itself and 2 other NO donors in a rat model of colitis. These drugs were compared for their ability to inhibit leukocyte adherence to the vascular endothelium in vivo, interleukin (IL)-1beta and interferon (IFN)-gamma release in vitro (splenocytes and colon), and messenger RNA expression in the inflamed colon. RESULTS: NO-mesalamine was significantly more effective than mesalamine in reducing the severity of colitis (damage and granulocyte infiltration). Unlike mesalamine, NO-mesalamine significantly suppressed leukocyte adherence to the vascular endothelium in vivo. NO-mesalamine inhibited IL-1beta and IFN-gamma release and caspase 1 activity in splenocytes; such effects were not found in the inflamed colon. CONCLUSIONS: These studies show that an NO-releasing derivative of mesalamine has significantly enhanced anti-inflammatory activity, including improved efficacy in a rat model of colitis. The improved efficacy of this derivative is most likely caused by its enhanced ability to suppress leukocyte infiltration and possibly to scavenge peroxynitrite.

Aminosalicylic Acids↗

PubMed1999

Equilibrium and kinetics of rotamer interconversion in immunosuppressant prodigiosin derivatives in solution.

The equilibrium and relative rate of rotamer interconversion around the bond joining the 2,2'-bipyrrolyl and pyrromethene moieties in a synthetic analogue of immunosuppressant prodigiosin are investigated as a function of pHapp in a water/acetonitrile mixture (1/1 by volume). Two chromatographically separable isomeric forms are obtained in acid solutions (pHapp < 4), whereas rapid interconversion occurs above neutrality. Furthermore, pH modulates the conformational preference of the molecule according to nitrogen protonation on the three pyrrole rings system (pKa = 7.2). At high pHapp (neutral form), the same conformer that is observed in pure acetonitrile prevails, whereas the other one is preferred by the protonated form. The nuclear magnetic resonance data indicate that the structures of the two conformers mainly differ in the value of the torsion angle around the aforementioned C-C bond. Kinetic and equilibrium data are quantitatively interpreted with a cyclic mechanism including two protonation (pKa1 = 8.23 +/- 0.03, pKa2 = 5. 4 +/- 0.2) and two conformational rearrangement steps. A molecular interpretation of the observed behavior includes, for the preferred conformer at low pH, formation of a new hydrogen bond between the exocyclic oxygen and the neighboring pyrrole NH upon protonation of the three pyrrole rings system.

Chromatography, High Pressure Liquid↗

PubMed1999

Nitric oxide-releasing NSAIDs inhibit interleukin-1beta converting enzyme-like cysteine proteases and protect endothelial cells from apoptosis induced by TNFalpha.

BACKGROUND: Nitric oxide (NO)-releasing NSAIDs are a new class of NSAID derivatives with markedly reduced gastrointestinal toxicity. Although it has been demonstrated that NO-NSAIDs spare gastric mucosal blood flow, molecular determinants involved in this effect are unknown. AIM: To investigate the effect of aspirin, naproxen and flurbiprofen, and their NO-derivatives, on gastric apoptosis and endothelial cell damage induced by tumour necrosis factor-alpha (TNFalpha). In other systems, TNFalpha-induced apoptosis is mediated by caspases, a growing family of cysteine proteases similar to the IL-1beta converting enzyme (ICE), and so we have investigated whether NO-NSAIDs modulate ICE-like endopeptidases. METHODS: Rats were treated orally with aspirin, naproxen and flurbiprofen, or their NO-releasing derivatives in equimolar doses, and were killed 3 h later to assess mucosal damage and caspase activity. Endothelial cells (HUVECs) were obtained from human umbilical cord by enzymatic digestion. Caspase 1 and 3 activities were measured by a fluorimetric assay using selective peptides as substrates and inhibitors. Apoptosis was quantified by ELISA specific for histone-associated DNA fragments and by the terminal transferase nick-end translation method (TUNEL). RESULTS: In vivo NSAID administration caused a time-dependent increase in gastric mucosal damage and caspase activity. NCX-4016, NO-naproxen and NO-flurbiprofen did not cause any mucosal damage and prevented cysteine protease activation. NSAIDs and NO-NSAIDs stimulated TNFalpha release. Exposure to TNFalpha resulted in a time- and concentration-dependent HUVEC apoptosis, an effect that was prevented by pretreating the cells with NCX-4016, NO-naproxen, NO-flurbiprofen, SNP or Z-VAD.FMK, a pan-caspase inhibitor. The activation of ICE-like cysteine proteases was required to mediate TNFalpha-induced apoptosis of HUVECs. Exogenous NO donors inhibited TNFalpha-induced cysteine protease activation. Inhibition of caspase activity was due to S-nitrosylation of ICE/CPP32-like proteases. NO-NSAIDs prevented IL-1beta release from endotoxin-stimulated macrophages. CONCLUSIONS: NO-releasing NSAIDs are a new class of non-peptide caspase inhibitors. Inhibition of ICE-like cysteine proteases prevents endothelial cell damage induced by pro-inflammatory agents and might contribute to the gastro-protective effects of NO-NSAIDs.

Animals↗

PubMed1999

Human primary fibroblasts in vitro express a purinergic P2X7 receptor coupled to ion fluxes, microvesicle formation and IL-6 release.

We have investigated reponses to extracellular ATP in human fibroblasts obtained by skin biopsies. Our data show that these cells express a P2X7 purinergic receptor, as judged by (1) RT-PCR with specific primers, (2) reactivity with a specific anti-P2X7 antiserum, (3) activation by the selective P2X agonist benzoylbenzoylATP and (4) stimulation of transmembrane ion fluxes. Stimulation with benzoylbenzoylATP, and to a lesser extent with ATP, also caused striking morphological changes and increased formation of cytoplasmic microvesicles. These changes were fully reversible upon nucleotide removal. Two known blockers of P2X receptors, oxidised ATP and pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid, inhibited the morphological changes fully and the ion fluxes partially. The residual rise in intracellular Ca2+ levels and membrane depolarization observed in the presence of the inhibitors were dependent upon activation of a P2Y-type receptor exhibiting a peculiar pharmacological profile, in that CTP was the preferred agonist. ATP stimulation triggered release of the pro-inflammatory cytokine IL-6 in fibroblasts pre-treated with PMA and bacterial endotoxin. These observations reveal a novel pathway for fibroblast activation and for their recruitment in the inflammatory response.

Blotting, Western↗

PubMed1999

FokI polymorphism at translation initiation site of the vitamin D receptor gene predicts bone mineral density and vertebral fractures in postmenopausal Italian women.

A novel T/C polymorphism (ATG to ACG) at the translation initiation site of the vitamin D receptor (VDR) gene, defined by FokI restriction endonuclease, has been recently associated with variation in bone mineral density (BMD) and rates of bone loss in a group of postmenopausal Mexican-American women. The presence of the restriction site, designated as f, allows protein translation to initiate from the first ATG, while the allele lacking the site, indicated as F, initiates translation at a second ATG. In this study, we investigated the role of FokI polymorphism in a group of 400 postmenopausal women of Italian descent stratified for BMD into osteoporotic (n = 164), osteopenic (n = 117), and normal (n = 119) groups. There were 159 (41%) FF homozygotes, 55 (14%) ff homozygotes, and 186 (45%) Ff heterozygotes. In the whole population, we observed a weak association between FokI polymorphism and lumbar BMD (p = 0.06, analysis of covariance [ANCOVA]) but not with femoral neck BMD (p = 0.5, ANCOVA). Interestingly, the effect of FokI genotypes on lumbar BMD was influenced by the years since menopause such that differences in BMD related to different VDR allelic variants were greater among women in the first 5 years of menopause (p = 0.04, ANCOVA), progressively declining afterward. In addition, a significantly higher prevalence of ff genotype in osteoporotic than in osteopenic and normal women was observed (p = 0.04, Chi-square test). Finally, ff genotype resulted significantly over-represented in the group of women with a vertebral fracture as compared with controls (p = 0.003, Chi-square test), equivalent to a relative risk of 2.58 (95% confidence intervals 1.36-4.91). We conclude that in this population, FokI polymorphism at the VDR gene locus accounts for a part of the heritable component of BMD at the lumbar spine.

Aged↗

PubMed1999

Pathogenesis of non-steroidal anti-inflammatory drug gastropathy.

Although non-steroidal anti-inflammatory drugs (NSAIDs) may impair the defensive ability of the gastric mucosal barrier through topical actions, recent evidence suggests that microcirculation disturbance plays a pivotal role in the genesis of gastric mucosal damage. In particular, attention has been drawn to the role exerted by those cytokine (TNF alpha and IL-1 beta) and adhesion molecules (LFA-1, Mac-1, ICAM-1) that regulate interactions between leukocyte and endothelial cells leading to gastric microvessels occlusion and ischaemic/hypoxic endothelial-epithelial cell damage. In recent years the role of prostaglandin synthesis inhibition in the pathogenesis of NSAID-gastropathy has been reconsidered, highlighting the immunomodulatory and pro-inflammatory consequences of prostanoids suppression. The awareness that mucosal damage is due to the non-discriminatory effect of NSAIDs on cyclo-oxygenase (COX) isoenzymes, has lead to the development of more selective, safer, COX-2 inhibitors. On the other hand, the observation that NO exerts a predominant physiological role in the maintenance of mucosal integrity has raised the opportunity to develop a new generation of NO-releasing NSAID derivatives with a reduced gastrointestinal toxicity.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1999

[Problems in anesthesia in pulmonary cystic adenomatosis].

Congenital cystic adenomatoid malformation (CCAM) of the lung is a rare disease. It is about an abnormal proliferation of mesenchymal elements and failure of maturation of bronchiolar structures, characterized by the replacement of normal pulmonary tissue with "cysts" in variable size and number. These lesions communicate with the tracheobronchial tree. During fetal period hydrops and polyhydramnios can be associated with CCAM. A cystic adenomatoid malformation can be detected by antenatal ultrasound, and, at the birth, it is confirmed by chest radiography. From January 1990 to December 1998, 24 cases with CCAM came to our observation; 16 of these patients underwent surgery and 14 have come to a complete recovery. The newborns, with CCAM, can show early acute respiratory distress for rapid expansion of the cysts leading to compression of normal lung and mediastinal shift. Conventional mechanical ventilation may cause further expansion of the involved lobe with a ball-valve effect: this take a clinical deterioration. Perioperative ventilatory management with high frequency oscillation (HFO) is useful to stabilize and to improve arterial blood gases of this patients. At the moment, thanks to the early prenatal sonographic diagnosis, it is possible, and strongly advisable, after adequate serial checkings during the pregnancy, to refer CCAM cases to a tertiary centre that is properly equipped, where a poly-specialist team consisting of obstetrician, neonatologist, pediatric anesthetist and pediatric surgeon, will be able to plan and arrange in the best treatment necessary for the newborn.

Anesthesia↗

PubMed1999

PCNA positivity in the telencephalic matrix areas in the adult of a lizard, Podarcis sicula.

In the present paper a reappraisal is made of the persistence and size of telencephalic matrix areas in normal adult specimens of a lizard, Podarcis sicula, using a recent in situ marker of cells in the S phase, the Proliferating Cell Nuclear Antigen (PCNA), belonging to the cyclin family, proteins that regulate the cell cycle and that can be immunocytochemically evidenced using monoclonal antibodies. Only a small number of positive PCNA elements, randomly arranged in the dorsal (medial and lateral) matrix areas, were found in the telencephalic ependymal tissue. These elements were found in larger numbers and distributed more uniformly in the ventral matrix areas, both opposite the ventricular lumen and outside the ependyma.

Animals↗

PubMed1999

PCNA positivity in the telencephalic matrix areas in the adult of a newt, Triturus carnifex.

The Proliferating Cell Nuclear Antigen (PCNA) is an auxiliary protein of the DNA polymerase delta, belonging to the cyclin family, which attains appreciable levels only in those phases of the cell cycle in which DNA synthesis occurs. Using an immunocytochemical method that exploits this proliferative marker, we observed a certain PCNA positivity in the telencephalon of normal adult individuals of Triturus carnifex. The elements that display this peculiarity occupy an ependymal and/or sub-ependymal site. They are located in the anterior portion of the telencephalon only at the dorsal level and tend to decrease in number until they disappear temporarily as the intermediate portion is approached. In the posterior portion of the telencephalon, the dorsal labelling patterns, the size of which is however smaller than that observed more anteriorly, reappear and in the ventral region a large population of labelled cells appears. Then, again proceeding in a caudal direction, while the PCNA-positive elements lying dorsally diminish and disappear, they persist in the ventral region and gradually taper off until they final disappear where the telencephalic ventricles come together. This immunocytochemical picture supports the findings of other authors in adult Urodeles under both normal and experimental conditions (with classical and autoradiographic histological techniques) concerning the persistence of the telencephalon in dorsal and ventral germinative areas responsible for physiological and plastic neurogenetic events.

Animals↗

PubMed1998

Forskolin induces U937 cell line differentiation as a result of a sustained cAMP elevation.

The present study examines the effects of forskolin on U937 cell differentiation. We recently reported that dibutyryl cAMP (dbcAMP), but not cAMP-elevating agents such as histamine, promotes U937 cell differentiation. cAMP production elicited by stimulation of histamine H2 receptors showed a rapid, homologous desensitization, which might explain the dissimilar responses to histamine and dbcAMP. Forskolin induced an increase in cAMP levels in a concentration-dependent manner (EC50=30 microM) for an extended period of at least 24 h. Forskolin but not histamine (up to 100 microM), also inhibited cell growth in a dose-dependent fashion (EC50=22 microM). After 3 days of incubation, 75 microM forskolin induced U937 cell differentiation as judged by an increased rate of reduction of nitrobluetetrazolium (mean+/-S.E.M.: 21.3+/-6.6% in treated cells vs. 3.2+/-1.9% in the control group, P < 0.001) and an augmented chemotactic response to complement 5a (C5a) (33.2+/-5.9% in forskolin-treated vs. 0.34+/-0.12% in control cells, P < 0.01). Furthermore, c-Myc levels decreased following forskolin treatment, while the histamine H2 receptor agonist dimaprit had no effect. We conclude that forskolin induces U937 cell differentiation through a sustained rise in cAMP levels.

Antigens, Neoplasm↗

PubMed1998

Measurements of (Na+,K+)ATPase after in vitro hypoxia and reoxygenation are affected by methods of membrane preparation.

(Na+,K+ )ATPase activity was evaluated in membranes from rat hippocampal slices after in vitro hypoxia and reoxygenation. Membranes were prepared with two different methods, one using an isotonic medium and another using a hypotonic one. The changes that were found after hypoxia went into opposite directions in the two cases. Membranes prepared in a hypotonic medium are probably more suitable for these measurements. Using these membranes, hypoxia results in a slight decrease of (Na+,K+)ATPase activity and in a further decrease after reoxygenation. We also found that expressing (Na+,K+)ATPase activity as a percent of total ATPase activity is appropriate for membranes prepared under hypotonic conditions and can unveil (by reducing variability between experiments) significant changes that may be masked in small samples like ours.

Animals↗