Spherical ion kinetic simulations of DT implosions.
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Journal Article↗
Biomedical subjects
M Casanova
Publications and source records attributed to M Casanova.
Evidence for the presence of collagenous domains in Candida albicans cell surface proteins.
Rabbit polyclonal antibodies (PAbs) directed towards the amino-terminal cysteine-rich 7S domain (PAb anti-7S), the major internal collagenous domain (PAb anti-type IV), and the C-terminal noncollagenous region (PAb anti-NC1) of the type IV collagen molecule were probed by indirect immunofluorescence against Candida albicans blastoconidia and germinated blastoconidia. Most nongerminating cells and mother blastoconidia from which germ tubes originated showed strong fluorescence when PAb anti-7S was used, whereas with PAb anti-type IV, fluorescence was found almost exclusively on the surface of filamentous forms. A patched fluorescent pattern rather than a homogenous confluent fluorescence was observed in all cases. No fluorescent cells were observed with PAb anti-NC1. By Western immunoblotting, PAb anti-type IV cross-reacted primarily with a polypeptide of 37 kDa present in wall extracts obtained from intact cells of both growth forms by treatment with beta-mercaptoethanol, whereas PAb anti-7S recognized a major 58-kDa antigen also present in both extracts, along with some other high-molecular-mass (> 106-kDa) polydisperse species present only in the material released from blastoconidia with beta-mercaptoethanol. No reactive bands were observed when PAb anti-NC1 was used as a probe in Western immunoblotting experiments. The sensitivities or resistances to collagenase digestion of the different polypeptides that cross-reacted with PAbs anti-type IV and anti-7S suggest the existence of cell wall components in C. albicans that contain epitopes that mimic the collagenous domains of the type IV collagen molecule.
Animals↗
DNA-protein cross-links and cell replication at specific sites in the nose of F344 rats exposed subchronically to formaldehyde.
Chronic exposures to high concentrations (> or = 6 ppm) of formaldehyde (HCHO) induce cell proliferation, squamous metaplasia, and squamous cell carcinomas in F344 rats. To assess the cancer risk associated with HCHO exposure, DNA-protein cross-links (DPX) formed in a single exposure of naive (previously unexposed) rats and monkeys have been used as a surrogate for the internal dose. Since the quantity of DPX may differ in subchronically exposed animals, the effects of preexposure to HCHO on the acute DPX yield (concentration of DPX following a single exposure) and the cumulative DPX yield (concentration of DPX following repeated exposures) were determined. Male F344 rats were preexposed (PE) to 0.7, 2, 6, or 15 ppm of HCHO (6 hr/day, 5 days/week, 11 weeks + 4 days). Naive (N) rats were exposed to room air. On the 5th day of the 12th week, PE and N rats were simultaneously exposed (3 hr) to H14CHO at the same concentrations used for preexposure. Acute DPX yields and cell replication (incorporation of 14C into DNA) were determined in the mucosal lining of the nasal lateral meatus (LM) (high tumor site in HCHO bioassay) and the medial and posterior meatuses (M:PM) (low tumor site in bioassay). DPX yields in the LM were approximately sixfold higher than in the M:PM. At 0.7 and 2 ppm, no differences between PE and N rats were detected in either tissue. At 6 and 15 ppm, acute DPX yields in the LM of PE rats were approximately half those of N rats, but no differences were detected in the M:PM. Cell proliferation was induced in PE rats at 6 ppm (LM only) and especially at 15 ppm (LM and M:PM). Cumulative DPX yields were measured indirectly by determining the decrease in extractability of DNA from proteins. PE rats were preexposed to 6 or 10 ppm as above, while N rats were exposed to room air. Both groups (PE and N) were then exposed (3 hr) to the same concentration of unlabeled HCHO. DPX yields increased in a concentration-dependent manner in both groups, but the yields were smaller in PE than N rats, suggesting that no accumulation of DPX occurred in PE rats. The results demonstrate that at concentrations < or = 2 ppm, N and PE rats are equivalent with respect to the formation of DPX.(ABSTRACT TRUNCATED AT 400 WORDS)
Administration, Inhalation↗
Changes in the cell wall glycoprotein composition of Candida albicans associated to the inhibition of germ tube formation by EDTA.
Hyphal development in Candida albicans was blocked by EDTA. This effect was not due to a general growth inhibition since the chelator did not affect protein and DNA synthesis. Recovery of mycelial growth was observed when EDTA-grown cells were incubated at 37 degrees C in EDTA-free medium. High-molecular-weight mannoproteins (HMWM) that are mycelium-specific wall components, and particularly a 260-kDa species (HMWM-260), were absent in the wall of cells grown under germination conditions in the presence of EDTA. Synthesis of the HMWM-260 species was not inhibited but its incorporation (secretion) into the wall structure seemed to be blocked in EDTA-treated cells.
Candida albicans↗
A comparative study on cell wall antigens and cell surface hydrophobicity in clinical isolates of Candida albicans.
Characterization of common cell surface-bound antigens in Candida albicans strains, particularly those expressed in the walls of mycelial cells might be useful in the diagnosis of systemic candidiasis. Hence, antigenic similarities among wall proteins and mannoproteins from C. albicans clinical serotype A and B isolates, were studied using polyclonal (mPAbs) and monoclonal (MAb 4C12) antibodies raised against wall antigens from the mycelial form of a common C. albicans serotype A laboratory strain (ATCC 26555). Zymolyase digestion of walls isolated from cells of the different strains studied grown at 37 degrees C (germination conditions), released, in all cases, numerous protein and mannoprotein components larger than 100 kDa, along with a 33-34 kDa species. The pattern of major antigens exhibiting reactivity towards the mPAbs preparation was basically similar for all the serotype A and B isolates, though minor strain-specific bands were also observed. The immunodeterminant recognized by MAb 4C12 was found to be absent or present in very low amounts in C. albicans isolates other than the ATCC 26555 strain, yet high molecular weight species similar in size (e.g., 260 kDa) to the wall antigen against which MAb 4C12 was raised, were observed, particularly in wall digests from serotype A strains. Cell surface hydrophobicity, an apparently important virulence factor in C. albicans, of the cell population of each serotype B strain was lower than that of the corresponding serotype A counterparts, which is possibly due to the fact that the former strains exhibited a reduced ability to form mycelial filaments under the experimental conditions used.
Animals↗
Evidence for the presence of a high-affinity laminin receptor-like molecule on the surface of Candida albicans yeast cells.
Two polypeptides of 37 and 67 kDa that bind laminin were detected in cell wall extracts of Candida albicans blastoconidia. The 37-kDa species, found only in yeast cell wall extracts, cross-reacted with a rabbit polyclonal antibody (PAb 4160) directed towards the carboxyl-terminal laminin-binding domain present in the human 67-kDa high-affinity laminin receptor (67LR) and its 37-kDa precursor (37LRP), whereas another antibody (PAb 4056), directed against internal domains of 67LR and 37LRP, recognized a 37-kDa species in wall extracts from both blastoconidia and germinated blastoconidia. Indirect immunofluorescence with PAb 4160 showed a patchy binding pattern only on yeast cells that represented about 10% of the entire blastoconidia population.
Amino Acid Sequence↗
Myocardial mitogenic effect of erythropoietin through the activation of Na(+)-K(+)-ATPase activity.
Erythropoietin is considered unique among the hematopoietic growth factor with a specific action on the differentiation and proliferation of erythroid progenitor cells. We have observed a dose-dependent modulatory action of human recombinant erythropoietin (rHuEpo) stimulated the rate of cell growth but at higher ones (3-10 U/ml) inhibited it. The mitogenic action of the hormone is correlated with cardiac membrane Na(+)-K(+)-ATPase activity since concentrations of rHuEpo that increased cell growth stimulated paranitrophenilphosphatase (pNPPase) activity, while those concentrations that inhibit the enzyme markedly bloqued its mitogenic action. Moreover, ouabain (10(-5) M), concentration that inhibits Na(+)-K(+)-ATPase activity, blunted the stimulatory action of rHuEpo on cell proliferation. We also demonstrated that rHuEpo while activated the cardiac membrane Na(+)-K(+)-ATPase was able to alter the contractile action of ouabain on isolated neonatal rat atria. Indeed rHuEpo (1 U/ml) enhanced the non toxic action of the cardiac glycoside attenuating and delaying the onset of the toxic effect of the drug. These results show that rHuEpo has a non hematopoietic cardiac effect, associated with the cardiac Na(+)-K(+)-ATPase activity, that regulates the myocytes growth and the biological action of cardiac glycosides on isolated rat myocardium.
Animals↗
Biological stability of mRNA isolated from human postmortem brain collections.
RNA isolated from frozen human postmortem brain tissue was evaluated for its utility in molecular biological studies. Samples varying in postmortem interval, delay period before freezing, and long-term freezer storage were analyzed. It was found that storage of human postmortem brain at -70 degrees C for more than 5 years may compromise its use for oligo-dT primed library construction and in vitro expression studies. Although biological competency of the messenger RNA may be affected by long-term freezer storage of human brain, enough full-length or partial transcripts remained for amplification by the polymerase chain reaction. We conclude that human postmortem brain collections will continue to be valuable resources for the study of gene expression and isolation of nucleotide sequences.
Adult↗
The possible association between affective disorder and partially deleted mitochondrial DNA.
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Brain↗
Diagnosis of systemic candidiasis by enzyme immunoassay detection of specific antibodies to mycelial phase cell wall and cytoplasmic candidal antigens.
Diagnosis of systemic Candida infections was attempted by the use of an enzyme-linked immunosorbent assay (EIA) to detect IgG antibodies towards cell wall-bound and cytoplasmic candidal antigens. Cell wall antigens were sequentially solubilized by treatment of germinated blastoconidia of Candida albicans (ATCC 26555 strain) with beta-mercaptoethanol (beta ME extract) and digestion with Zymolyase 20T, a beta-glucanase preparation (Zymolyase extract). Protoplasts obtained after treatment with Zymolyase were osmotically lysed (cytoplasmic antigens). Sera were obtained from patients with systemic (n = 28) and superficial (n = 46) candidiasis. Control sera were obtained from normal healthy individuals (n = 31) and from hospitalized patients at low (n = 36) and at high (n = 13) risk of developing systemic candidiasis yet showing no symptoms of candidal infection. Detection of antibodies in crude sera samples by EIA using all of these antigenic extracts was highly specific (98-100%), but sensitivity of the method was low (3.5-17.8%). However, adsorption of sera with latex microspheres coated with purified Candida mannan in order to selectively remove anti-mannan antibodies prior to EIA improved the diagnostic efficiency of this test. Improvement was particularly noticeable when the beta ME extract was used as antigenic preparation, yielding a sensitivity of 89.2% and a specificity of 98.6%.
Antibodies, Fungal↗
[The nonpharmacological treatment of tachyarrhythmias in 23 children and adolescents].
We comment the results with non pharmacological treatment in 23 patients (mean age 11 +/- 4 years) with multiple episodes of palpitations, most of them required intravenous drugs for interrupting it. Twenty-eight procedures were performed, 17 catheter ablation and 11 surgical interventions. The energy source employed for fulguration until 1990 was DC and since 1991 radiofrequency. The best results with catheter ablation were obtained with accessory pathways. Interruption was achieved in all patients after a mean of 1.2 sessions per patient, but it was definitive in only 72%. Most of the patients (81%) remained asymptomatic without antiarrhythmic drugs. Nine patients with accessory pathways underwent surgery interruption, it was achieved in all; only one patient had arrhythmia recurrence, due to a second pathway in a different localization. We could not ablate a ectopic atrial tachycardia, that underwent surgery. There was only one indication for surgery in a patient with ventricular tachycardia. Catheter ablation does not present technical problem in children and teenagers, different from adults. The presented results lead us to suppose that the indications for non pharmacological treatment in the young will become more common.
Adolescent↗
[Kawasaki's syndrome: the importance of an early diagnosis].
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Humans↗
Cerebellar and frontal cortical benzodiazepine receptors in human alcoholics and chronically alcohol-drinking rats.
Postmortem cerebellar and frontal cortical membrane homogenates from human alcoholics, control subjects without neurological or psychiatric illnesses, and rats that chronically drank alcohol were studied to determine the binding characteristics of an imidazobenzodiazepine, [3H]Ro 15-4513. This ligand binds to classical gamma-aminobutyric acidA (GABAA)/benzodiazepine receptors, as well as to a "diazepam-insensitive" site associated with the GABAA receptor complex in the cerebellar granule cell layer. There were no differences in the density of the binding sites between alcoholics and their controls, between alcohol-drinking AA rats that had a choice between 10% alcohol or water for about 10 weeks and their controls, or between Wistar rats that had been given 20% alcohol as their only fluid for 4 months and their controls, which were pair-fed isocalorically with sucrose. The affinity for the cerebellar binding of [3H]Ro 15-4513 was higher in the alcoholics than the controls. No differences were observed in the frontocortical binding. No affinity differences were observed in the rat models. There were no differences between the groups in the characteristics of [3H]Ro 15-4513 binding to human cerebellum in the presence of micromolar diazepam, thus revealing the diazepam-insensitive binding. When this component was subtracted from the total cerebellar binding, to reveal the diazepam sensitive binding, both the KD and Bmax were lower in the alcoholic than the control group. The binding of [3H]muscimol, a GABAA agonist, tended to be higher in the frontal cortices of alcoholics; a similar trend for greater effects was observed in the alcoholics for the GABA inhibition of [3H]Ro 15-4513 binding. These results suggest that no drastic changes occur through chronic alcohol abuse in the numbers of cerebellar and frontocortical benzodiazepine receptors in humans and rodent models; however, the data indicate that the alcoholics have either acquired or innate differences in classical benzodiazepine recognition sites of the cerebellum and in the coupling of these sites to GABAA sites in the frontal cortex, without any differences in cerebellar granule cell-specific diazepam-insensitive [3H]Ro 15-4513 binding sites.
Adult↗
Search for cytomegalovirus in the postmortem brains of schizophrenic patients using the polymerase chain reaction.
Cytomegalovirus infection has a number of features that suggest a possible association between congenital infection and schizophrenia. Previous studies have investigated anticytomegalovirus antibody titers or attempted directly to identify viral antigens in body fluids or brain tissue from schizophrenic subjects but have been limited by the sensitivity of the available methods. The highly sensitive polymerase chain reaction, a newly developed technique for gene amplification, was used to search for cytomegalovirus in the DNA extracted from postmortem temporal cortex samples of eight schizophrenic subjects, eight nonschizophrenic suicide victims, and eight normal controls. Cytomegalovirus-specific DNA amplification was not detected in any of the samples. The implications of this finding for the viral hypothesis of schizophrenia are discussed.
Adult↗
Dichloromethane (methylene chloride): metabolism to formaldehyde and formation of DNA-protein cross-links in B6C3F1 mice and Syrian golden hamsters.
Dichloromethane (DCM) is metabolized via a glutathione transferase (GST)-dependent pathway to formaldehyde (HCHO), a mutagenic compound that could play an important role in the carcinogenic effects of DCM observed in the liver and lungs of B6C3F1 mice at 2000 and 4000 ppm. Syrian hamsters metabolize DCM more slowly than mice via this pathway, and hamsters exposed to 3500 ppm showed no apparent carcinogenic response. The possible formation of DNA-protein cross-links (DPX) from DCM in both species was examined. Male mice and hamsters were pre-exposed for 2 days (6 hr/day) to 4000 ppm of DCM and on the third day were exposed (6 hr) to a decaying concentration (4500 to 2500 ppm) of [14C]DCM. DPX were detected in mouse liver, but not in mouse lung, hamster liver, or hamster lung. The failure to detect DPX in mouse lung does not exclude their possible formation in a subpopulation of lung cells. Metabolic incorporation of 14C derived from [14C]DCM into DNA suggested a higher rate of turnover of some mouse lung cells than of hamster lung cells, but no large difference in the turnover rates of liver cells in the two species under these conditions. These results demonstrate that HCHO derived from DCM can form DNA-protein cross-links in the liver of the B6C3F1 mouse. The formation of DPX is dependent on the activity of the GST pathway, and species such as hamsters and humans having much lower rates of DCM metabolism via this pathway may not generate toxicologically significant concentrations of HCHO and DPX.
Animals↗
Acute Chagas' disease (Trypanosomiasis americana) in acquired immunodeficiency syndrome: report of two cases.
Two heterosexual men, aged 31 and 40 years, with the acquired immunodeficiency syndrome and presenting with the acute form of Chagas' disease are reported. The first patient, a carrier of hemophilia A, was treated for 20 years with Chilean and Brazilian cryoprecipitates. This patient acquired both diseases through this medium. The second patient, an inhabitant of northern Chile (fourth region), was allegedly bitten by Triatoma infestans and was an intravenous drug addict. The hemophilic patient presented with a neurologic syndrome; a brain biopsy showed a necrotizing encephalitis with an obliterative angiitis and abundant macrophages. The second patient developed intractable congestive heart failure; necropsy showed a dilated myocarditis with rupture of myofibers and an inflammatory infiltrate rich in plasma cells, lymphocytes, and macrophages. Using light and electron microscopy, abundant amastigotes of Trypanosoma cruzi were seen in brain tissue, especially in the cytoplasm of macrophages, as well as in some myocardial fibers. In both cases, determination of anti-T cruzi antibodies (indirect hemagglutination technique) and xenodiagnosis were positive.
Acquired Immunodeficiency Syndrome↗
Search for evidence of herpes simplex virus, type 1, or varicella-zoster virus infection in postmortem brain tissue from schizophrenic patients.
The highly sensitive polymerase chain reaction (PCR) was used to search for herpes simplex virus type 1 (HSV-I) or varicella-zoster virus (VZV) in the DNA extracted from postmortem temporal cortex samples of 8 schizophrenic subjects, 8 nonschizophrenic suicide victims and 8 normal controls. HSV-I or VZV-specific DNA amplification was not detected in any of the samples studied.
Base Sequence↗
Identification of a 58-kilodalton cell surface fibrinogen-binding mannoprotein from Candida albicans.
Treatment of both yeast (blastoconidia) and hyphal (blastoconidia with germ tubes) cells of Candida albicans with beta-mercaptoethanol (beta ME) releases a complex array of cell wall-bound proteins and glycoproteins. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western immunoblotting with fibrinogen-anti-fibrinogen antibody allowed the identification of a 58-kDa mannoprotein (mp58) in both extracts which specifically interacts with human fibrinogen. Treatment of intact cells with low concentrations of beta-glucanase (Zymolyase 20T) for short periods or with beta ME abolished or significantly reduced binding of fibrinogen. A rabbit polyclonal antiserum was raised against the purified mp58 species released by beta ME from germinated blastoconidia (PAb anti-mp58). By Western blotting, the antiserum cross-reacted with the homologous 58-kDa fibrinogen-binding mannoprotein present in beta ME extracts from blastoconidia, and by indirect immunofluorescence, the antiserum labelled both yeast cells and hyphae, yet reactivity was found primarily on the cell surface of filamentous forms. Immunostaining of human infected tissue sections with PAb anti-mp58 showed that the mp58 species is also expressed in vivo; in this case, the species is in the forms of both yeast and hyphal elements similarly labelled by the antiserum. Purified immunoglobulin G fraction from the antiserum did not alter the binding of fibrinogen as determined by a modified enzyme-linked immunosorbent assay and Western blotting. The N- and O-glycosidically linked carbohydrates represent 18 to 20% and 3 to 4%, respectively, of the molecular mass of the mp58. O-linked sugar residues may be involved in the interaction of the molecule with fibrinogen.
Animals↗