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Biomedical subjects

M A Moreno

Publications and source records attributed to M A Moreno.

At least 73 records · Page 4Linked to original sources
PubMed1992

Purification and biochemical properties of calmodulin in Entamoeba histolytica and its distribution during secretion of electron-dense granules.

1. Calmodulin (CaM) was detected during secretion of electron-dense granules by Entamoeba histolytica trophozoites with immunofluorescence. 2. It was purified to apparent homogeneity by chromatography with a yield of 2.26 micrograms of calmodulin/mg of protozoan protein. Purity was established by gel electrophoresis. 3. The parasite calmodulin has properties characteristic of calmodulin isolated from other eukaryotes: an apparent molecular weight of 19 or 17 kDa in presence of EGTA or CaCl2, respectively, activation in a calcium dependent manner of bovine heart cyclic nucleotide phosphodiesterase, and its UV spectrum.

Animals↗
PubMed1992

Reconstitutional mutagenesis of the maize P gene by short-range Ac transpositions.

The tendency for Ac to transpose over short intervals has been utilized to develop insertional mutagenesis and fine structure genetic mapping strategies in maize. We recovered excisions of Ac from the P gene and insertions into nearby chromosomal sites. These closely linked Ac elements reinserted into the P gene, reconstituting over 250 unstable variegated alleles. Reconstituted alleles condition a variety of variegation patterns that reflect the position and orientation of Ac within the P gene. Molecular mapping and DNA sequence analyses have shown that reinsertion sites are dispersed throughout a 12.3-kb chromosomal region in the promoter, exons and introns of the P gene, but in some regions insertions sites were clustered in a nonrandom fashion. Transposition profiles and target site sequence data obtained from these studies have revealed several features of Ac transposition including its preference for certain target sites. These results clearly demonstrate the tendency of Ac to transpose to nearby sites in both proximal and distal directions from the donor site. With minor modifications, reconstitutional mutagenesis should be applicable to many Ac-induced mutations in maize and in other plant species and can possibly be extended to other eukaryotic transposon systems as well.

Alleles↗
PubMed1991

Transformation of sterigmatocystin and O-methylsterigmatocystin by aflatoxigenic and nonaflatoxigenic field isolates of the Aspergillus flavus group.

Transformation of sterigmatocystin and O-methylsterigmatocystin (two metabolic aflatoxin precursors) to aflatoxins by aflatoxigenic and nonaflatoxigenic field isolates of Aspergillus flavus was studied. The 24 nonaflatoxigenic isolates investigated failed to transform both precursors. Among the 8 aflatoxin-producing isolated used, 7 transformed both precursors whereas the remaining failed to transform both. According to these results, the usefulness of the measurement of enzymatic activities related to aflatoxin production in understanding the true status of conflictive field isolates is discussed.

Aflatoxins↗
PubMed1991

Possible role of calmodulin in the secretion of Entamoeba histolytica electron-dense granules containing collagenase.

Entamoeba histolytica cells secrete electron-dense granules (EDGs) that have collagenase activity. To study the possible involvement of calmodulin (CaM) on EDG secretion, the effect of several CaM antagonists (TFP, R24571, W-7, W-5, dibucaine and DL-propranolol) was tested on this cellular function. Except for W-5 and dibucaine, the rest of these compounds inhibited EDG secretion. Transmission electron microscopy of collagen-activated trophozoites showed numerous EDGs located in or near the surface membrane. In contrast, trophozoites incubated with TFP showed no EDGs. Protein kinase C inhibitors (H-7, ML-9) had no effect on EDG secretion, suggesting that CaM antagonists acted by selectively inhibiting CaM. These results suggest that a CaM-dependent process is involved in EDG secretion.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1991

Visual evoked potentials in dementia: selective delay of flash P2 in probable Alzheimer's disease.

The flash visual evoked potential P2 component is delayed in etiologically mixed groups of demented patients compared to healthy controls or nondemented patients. This study compared patients meeting both DSM-III-R criteria for dementia and NINCDS-ADRDA criteria for probable Alzheimer's disease (AD) with healthy elderly controls and found the P2 delay in the probable AD group. Additional comparisons found no evidence of a P2 delay in demented unlikely AD patients. These results suggest that earlier findings of a delayed P2 in etiologically mixed demented groups may have been due to inclusion of AD patients.

Aged↗
PubMed1991

Recurrent massive pleural effusion as a late complication of radiotherapy in Hodgkin's disease.

We report a very unusual case of a patient with recurrent massive PEs eight years after mediastinal radiotherapy for HD, in which evidence of lymphomatous recurrence could not be demonstrated. The diagnosis of PE as a complication of radiation is presumptive, and other disorders causing PE must be excluded. This condition requires symptomatic treatment and a close follow-up of the patient.

Adult↗
PubMed1991

Electrocortical mapping, MRI, and neuropsychological measures: evidence of Alzheimer's disease in the presence of vascular lesions.

We report here a case study of a 76-year-old woman with a high school education, whose presenting psychiatric symptomatology indicated dementia of unknown etiology. Neuropsychological test results were consistent with AD, but diagnosis was complicated by an MRI showing a large right hemisphere cortical infarct and scattered subcortical changes leading to a diagnosis of possible AD. Electrocortical mapping showed the right hemisphere infarct, and gave independent evidence suggestive of AD in the relatively intact left hemisphere. This case demonstrates the utility of multidimensional assessment as an aid to differential diagnosis.

Clinical Conference↗
PubMed1991

Cell lineage analysis of the gynoecium of maize using the transposable element Ac.

The maize gynoecium develops from a primordium comprising two distinct cell lineages: an epidermal LI and a subepidermal LII lineage. We have analyzed somatic gynoecial sectors marked with red flavonoid pigments by excision of Ac from the P locus. Somatic sector analysis indicates the epidermal lineage starts as a single cell layer at the base of the ovary and thickens into several cell layers, presumably by periclinal divisions, near the silk attachment point. The silk attachment point appears to be mainly an epidermal outgrowth of two of three fused carpels and presumably the silk contains only LI, or mostly LI, with only traces of subepidermal LII cells. The third carpel, covering the germinal face of the kernel, retains a multicellular LII and unicellular LI organization but fails to contribute substantially to stylar outgrowth. Ac transpositions in subepidermal somatic sectors are transmitted to the archesporial cell lineage. Ac transpositions that occur in epidermal sectors are not transmitted to offspring. These results demonstrate that the female megasporocyte is derived from subepidermal (LII) cells.

Clone Cells↗
PubMed1988

Considerations on the distribution of aflatoxigenic Aspergillus flavus in feeds.

The distribution of aflatoxin producing isolates of the Aspergillus flavus group in feeds was studied. Aflatoxin production was investigated by a sequential method previously reported (fluorescence in Coconut Agar Medium, rapid extraction from a wheat medium, and total extraction from the same wheat medium). Twenty-seven of 32 samples contained A. flavus, and 21 of them had at least one aflatoxicogenic isolate of A. flavus. Of the 115 isolates analysed, 65 produced aflatoxins, mainly B aflatoxins.

Aflatoxins↗
PubMed1988

Facts and artifacts in brain electrical activity mapping.

As computerized EEG (CEEG) analysis and display methods become increasingly powerful the user is lured toward increasingly abstract representations of data in which artifacts can easily go unrecognized. The presence of even small amounts of artifact can lead to distortion of CEEG results due to the sensitivity of the analysis methods employed. Several common artifacts are discussed, their distortion of CEEG data illustrated, and remedial measures suggested. Some of these artifacts (EOG, EMG, photomyoclonic, tremor, ECG, 60 Hz, volume conducted cortical activity) are familiar to traditional EEG (aliasing, extrapolation) are unique to CEEG and may be inadvertently introduced by workers not specifically trained in CEEG methods.

Brain Mapping↗
PubMed1987

Separation by high-performance liquid chromatography of penicillins with C4 to C10 aliphatic side chains.

A suitable and rapid method for the simultaneous determination of different aliphatic penicillins is described. Butyryl-, pentanoyl-, hexanoyl-, heptanoyl-, octanoyl-, nonanoyl- and decanoylpenicillin can be completely separated by high-performance liquid chromatography using an isocratic elution mode (50 mM H2KPO4, pH 5.0:methanol, 45:55 v/v). Under these conditions, retention times for C4 to C10 aliphatic side-chain penicillins were 2.5, 2.8, 4.1, 5.8, 8.9, 15.3, and 28.2 min. The benzylpenicillin retention time was 3.3 min.

Chromatography, High Pressure Liquid↗
PubMed1987

Effect of ultraviolet light irradiation on viability and aflatoxin production by Aspergillus parasiticus.

The effect of ultraviolet light irradiation (254 nm) on both the viability and the aflatoxin-producing ability of the fungus Aspergillus parasiticus NRRL 2999, a good aflatoxin-producing strain, was studied. This strain showed noticeable resistance and irradiation for more than 10 min was necessary to reduce survival to under 10%, while the white mutants were more susceptible (5 min of irradiation reduced survival to under 1%). Induction of mutants with complete loss of aflatoxigenicity was rare and only 3 of the 1463 survivors tested were aflatoxinless.

Aflatoxins↗
PubMed1978

Inhibition of African swine fever (ASF virus replication by phosphonoacetic acid.

Phosphonoacetic acid (PAA) inhibits the multiplication of African swine fever (ASF) virus in VERO cells. The observed inhibition of the in vivo DNA synthesis could be related to the in vitro inhibition of a virus-induced DNA polymerase activity present in cytoplasmic extracts from infected VERO cells.

African Swine Fever Virus↗
PubMed1976

Titration of African swine fever (ASF) virus.

A haemadsorption microtest for African swine fever (ASF) virus is described. This assay is as sensitive and its response is faster than the conventional assay which uses buffy coat cultures in Leighton tubes. The method can also process a larger number of samples by using smaller amounts of swine blood and laboratory space. A plaque assay for ASF virus adapted to grow in VERO cells gives a titre similar to that obtained using the haemadsorption microtest. In both the micromethod and the plaque assay infection may be produced by a single infective particle.

African Swine Fever Virus↗