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Biomedical subjects

A Petrescu

Publications and source records attributed to A Petrescu.

At least 19 recordsLinked to original sources
PubMed2001

West nile virus surveillance in Romania: 1997-2000.

In response to the 1996 West Nile (WN) fever epidemic that occurred in Bucharest and southeastern Romania, a surveillance program was established. The surveillance system detected 39 clinical human WN fever cases during the period 1997-2000: 14 cases in 1997, 5 cases in 1998, 7 cases in 1999, and 13 cases in 2000. Thirty-eight of the 39 case-patients lived in the greater Danube Valley of southern Romania, and 1 case-patient resided in the district of Vaslui, located on the Moldavian plateau. The estimated annual case incidence rate for the surveillance area during the period 1997-2000 was 0.95 cases per million residents. Thirty-four cases were serologically confirmed, and 5 cases were classified as probable. Twenty-four case-patients presented with clinical symptoms of meningitis (62%), 12 with meningoencephalitis (31%), 1 with encephalitis (3%), and 2 with febrile exanthema (5%). Five of the 39 cases were fatal (13%). Fourteen case-patients resided in rural areas, and 25 in urban and suburban areas, including 7 case-patients who resided in Bucharest. The ages of case-patients ranged from 8 to 76 years with a median age of 45 years. Twenty-four case-patients were males and 15 were females. Dates of onset of illness occurred from May 24 through September 25, with 82% of onset dates occurring in August and September. Limited entomological surveillance failed to detect WN virus. Retrospective sampling of domestic fowl in the vicinity of case-patient residences during the years 1997-2000 demonstrated seroprevalence rates of 7.8%-29%. Limited wild bird surveillance demonstrated seroprevalence rates of 5%-8%. The surveillance data suggest that WN virus persists focally for several years in poorly understood transmission cycles after sporadic introductions or that WN virus is introduced into Romania at relatively high rates, and persists seasonally in small foci.

Adolescent↗
PubMed2000

Sterol carrier protein-2 alters high density lipoprotein-mediated cholesterol efflux.

Although sterol carrier protein-2 (SCP-2) participates in the uptake and intracellular trafficking of cholesterol, its effect on "reverse cholesterol transport" has not been explored. As shown herein, SCP-2 expression inhibited high density lipoprotein (HDL)-mediated efflux of [(3)H]cholesterol and fluorescent 22-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3b-ol (NBD-cholesterol) up to 61 and 157%, respectively. Confocal microscopy of living cells allowed kinetic analysis of two intracellular pools of HDL-mediated NBD-cholesterol efflux: the highly fluorescent lipid droplet pool and the less fluorescent pool outside the lipid droplets, designated the cytoplasmic compartment. Both the whole cell and the cytoplasmic compartment exhibited two similar kinetic pools, the half-times of which were consistent with protein (t(b)(12) near 1 min) and vesicular (t(d)(12) = 10-20 min) mediated sterol transfer. Although SCP-2 expression did not alter cytoplasmic sterol pool sizes, the rapid t(b)(12) decreased 36%, while the slower t(d)(12) increased 113%. Lipid droplets also exhibited two kinetic pools of NBD-cholesterol efflux but with half-times over 200% shorter than those of the cytoplasmic compartment. The lipid droplet slower effluxing pool size and t(d)(12) were increased 48% and 115%, respectively, in SCP-2-expressing cells. Concomitantly, the level of the lipid droplet-specific adipose differentiation-related protein decreased 70%. Overall, HDL-mediated sterol efflux from L-cell fibroblasts reflected that of the cytoplasmic rather than lipid droplet compartment. SCP-2 differentially modulated sterol efflux from the two cytoplasmic pools. However, net efflux was determined primarily by inhibition of the slowly effluxing pool rather than by acceleration of the rapid protein-mediated pool. Finally, SCP-2 expression also inhibited sterol efflux from lipid droplets, an effect related to decreased adipose differentiation-related protein, a lipid droplet surface protein that binds cholesterol with high affinity.

4-Chloro-7-nitrobenzofurazan↗
PubMed2000

Pro-sterol carrier protein-2: role of the N-terminal presequence in structure, function, and peroxisomal targeting.

Although the 20-amino acid presequence present in 15-kDa pro-sterol carrier protein-2 (pro-SCP-2, the precursor of the mature 13-kDa SCP-2) alters the function of SCP-2 in lipid metabolism, the molecular basis for this effect is unresolved. The presequence dramatically altered SCP-2 structure as determined by circular dichroism, mass spectroscopy, and antibody accessibility such that pro-SCP-2 had 3-fold less alpha-helix, 7-fold more beta-structure, 6-fold more reactive C terminus to carboxypeptidase A, 2-fold less binding of anti-SCP-2, and did not enhance sterol transfer from plasma membranes. These differences were not due to protein stability since (i) the same concentration of guanidine hydrochloride was required for 50% unfolding, and (ii) the ligand binding sites displayed the same high affinity (nanomolar K(d) values) in the order: cholesterol straight chain fatty acid > kinked chain fatty acid. Laser scanning confocal microscopy and double immunofluorescence demonstrated that pro-SCP-2 was more efficiently targeted to peroxisomes. Transfection of l-cells or McAR7777 hepatoma cells with cDNA encoding pro-SCP-2 resulted in 45% and 59% of SCP-2, respectively, colocalizing with the peroxisomal marker PMP70. In contrast, l-cells transfected with cDNA encoding SCP-2 exhibited 3-fold lower colocalization of SCP-2 with PMP70. In summary, the data suggest for the first time that the 20-amino acid presequence of pro-SCP-2 alters SCP-2 structure to facilitate peroxisomal targeting mediated by the C-terminal SKL peroxisomal targeting sequence.

ATP-Binding Cassette Transporters↗
PubMed2000

High density lipoprotein-mediated cholesterol uptake and targeting to lipid droplets in intact L-cell fibroblasts. A single- and multiphoton fluorescence approach.

Fluorescent sterols, dehydroergosterol and NBD-cholesterol, were used to examine high density lipoprotein-mediated cholesterol uptake and intracellular targeting in L-cell fibroblasts. The uptake, but not esterification or targeting to lipid droplets, of these sterols differed >100-fold, suggesting significant differences in uptake pathways. NBD-cholesterol uptake kinetics and lipoprotein specificity reflected high density lipoprotein-mediated sterol uptake via the scavenger receptor B1. Fluorescence energy transfer showed an average intermolecular distance of 26 A between the two fluorescent sterols in L-cells. Indirect immunofluorescence revealed that both fluorescent sterols localized to L-cell lipid droplets, the surface of which contained adipose differentiation-related protein. This lipid droplet-specific protein specifically bound NBD-cholesterol with high affinity (K(d) = 2 nM) at a single site. Thus, NBD-cholesterol and dehydroergosterol were useful fluorescent probes of sterol uptake and intracellular sterol targeting. NBD-cholesterol more selectively probed high density lipoprotein-mediated uptake and rapid intracellular targeting of sterol to lipid droplets. Targeting of sterol to lipid droplets was correlated with the presence of adipose differentiation related protein, a lipid droplet-specific protein shown for the first time to bind unesterified sterol with high affinity.

4-Chloro-7-nitrobenzofurazan↗
PubMed1999

Evaluation of apoptosis of tumor and of apparently normal cells in human renal carcinoma.

Apoptosis of tumor cells and of apparently normal renal cells (ANRC) isolated from the same kidney in 42 untreated patients with renal carcinomas (RC) was evaluated. Thirty five of the investigated tumors were of Grawitz type in different grades of differentiation. The intensity of the apoptotic process was routinely assessed by propidium iodide staining and flow-cytometry analysis. Similar results were obtained in the same cases by using TUNEL assay, by staining with annexin V and by DNA electrophoresis. In 85% of Grawitz carcinomas the proportion of apoptotic tumor cells was quite high, with mean% +/- SD of 57.7+/-27.3, whereas in transitional cell carcinoma of the bladder (TCC), the mean percentage of cells in apoptosis was of 22.3+/-13.9. Unexpectedly, in ANRC displaying normal morphology and normal DNA content (diploidy), the mean% +/- SD of apoptotic cells were found to exceed that of apoptotic tumor cells, 79.2+/-21.6. The percentages of cells expressing Fas receptor and/or Fas ligand varied between large ranges in both tumor and ANRC, thus suggesting that other mechanisms are also involved in the activation of apoptosis. Immunohistochemical studies showed that the intensity of apoptosis correlated well with high p-53 and low bcl-2 expression. The intensity of apoptosis was generally not correlated with the cell proliferation index (S phase fraction), suggesting that in RC apoptosis can be activated in any stage of the cell cycle. Further investigations are necessary to understand the peculiar behaviour of tumor cells as well as of ANRC in renal carcinomas as compared to other types of malignancies.

Apoptosis↗
PubMed1999

Successful treatment with fludarabine in two cases of angioimmunoblastic lymphadenopathy with dysproteinemia.

Angioimmunoblastic lymphadenopathy with dysproteinemia (AILD) is today recognized as a T-cell lymphoma which in most cases runs an aggressive course. The diagnosis is often difficult because of the varying clinico-pathological picture. Less than a third of the patients can be expected to have long-term remissions even after multiagent chemotherapy. Complete remissions have been reported after the use of interferon-alpha, cyclosporin A, and recently purine analogues in a few patients. We now report two cases of AILD that had unmaintained remissions for 32 and 10 months, respectively, after fludarabine therapy. In one of the patients fludarabine was used up-front and in the other after she had proved to be resistant to CHOP treatment. No severe infectious complications were noted. The use of purine analogues should be investigated further in AILD.

Aged↗
PubMed1997

Genetic characterization of the bovine leukaemia inhibitory factor (LIF) gene: isolation and sequencing, chromosome assignment and microsatellite analysis.

The bovine leukaemia inhibitory factor was isolated from a phage library and sequences for the gene, in addition to 1213 bp of 5' and 432 bp of 3' sequences, were obtained and compared with other mammalian leukaemia inhibitory factor genes. Comparisons indicated amino acid homologies ranging from 89.6% to 77.2% with the human and mouse homologues, respectively. Analysis of 500 bp of 5' regulatory regions indicated homologies ranging from 83.6% to 74.4% with the corresponding human and sheep sequences, respectively. Additionally, bovine leukaemia inhibitory factor-specific primers were prepared, and a panel of bovine x hamster somatic cell lines were analysed by the polymerase chain reaction (PCR). Data indicated 93% concordance of leukaemia inhibitory factor with aldehyde dehydrogenase 2 located on bovine chromosome 17, and concordance of 81% with myelin basic protein situated on bovine chromosome 24. Southern analysis of selected hybrids confirmed the PCR results, thus conclusively assigning the bovine leukaemia inhibitory factor gene to chromosome 17. Sequence analysis also revealed a microsatellite in intron 2 of the bovine leukaemia inhibitory factor. Analysis of this region by PCR in 22 unrelated Bos taurus and 19 unrelated Bos indicus cattle detected nine different alleles. Polymorphic information content values were 0.53 and 0.80 in B. taurus and B. indicus, respectively. Additionally, the same leukaemia inhibitory factor primers successfully detected allelic variants at this locus in Bos javanicus, Bos guarus and Bison bison but not in Odocoileus virginianus.

Amino Acid Sequence↗
PubMed1984

Interaction of influenza and parainfluenza viruses with polycations, organic oligocations and chromosome preparations.

As evaluated by light scattering at 90 degrees, natural organic oligocations such as putrescine, spermidine and spermine interfered with myxovirus aggregates which were induced by the histone H2A and strongly amplified by shaking during incubation. In contrast, the synthetic oligocation 1.7-diamino heptane itself aggregated the virus particles, its action being unmodified by adding polycationic H2A in abundance. When human chromosome preparations treated with protamine solution and shaked during incubation were covered with a stable polycationic molecular layer, the chromosomes had become unstainable by the Giemsa method even if the dye was used in excess. Nevertheless, the affinity of influenza virus particles for protamine was so high that they were able to dissociate the protamine molecules from the preformed complexes reconstituting the affinity of chromosome preparations to Giemsa stain. The virus-caused shift in the staining ability of chromosomes did not occur when bacterial suspension was added instead of the viral one. The model of oligocationic relaxation and of polycation condensation accounting for the modulatory effects of polyamines is discussed.

Cations↗
PubMed1981

The action of simulated and true weightlessness on the digestive tract of rats.

Rats on board the Soviet Cosmos 936 satellite for l8 1/2 days showed a decreased glycoprotein secretion from the salivary mucous glands, stomach and intestine, and an increased leucine aminopeptidase and acid phosphatase content from the small intestine. Grimelius positive cells were activated. One group of rats were centrifuged at 1 g during the flight to simulate terrestrial gravity. Some investigations have suggested that under these conditions muscular and cardiac disorders diminished. In the digestive tract the benefits of centrifugation at 1 g are minimal and limited to a few glycoprotein components. The digestive changes are probably the expression of a stress response, unrelated to weightlessness. Similar changes, concomitant with a glycocorticoid hypersecretion, were found in rats after 15 days of hypokinesia on Earth. These digestive changes persisted even in adrenalectomized rats.

Acid Phosphatase↗
PubMed1981

Progressive oil-spot-like lesion in multiple sclerosis.

The demyelinating lesion in MS being characterised by an evolutive polymorphism, led to different opinions about the identification of the hypercellularity. The present work deals with data concerning the abundance and the early appearance of macrophages (M) within the lesion, studied with lipid histochemistry methods. The disposition of 3 various types of previously described M, with different lipid content, demonstrates the progressive centrifugal evolution of the recent lesion. At the edge the M are filled exclusively with intensely Baker (phospholipids) stained myelinic granules whereas inside they have a mixed myelinic and sudano-osmiophylic (esterocholesterolic) composition as revealed by Sudan red, Oil rd, Otan and Schultz methods. Surrounding vessels, in the centre of the lesion, M contain exclusively sudano-osmiophylic (esterocholesterolic) granules and crystals. This arrangement of M as to AGE is due to the progressive disintegrative cycle of phagocyted myelin: the youngest at the edge and those undergoing myelin disintegration towards the centre. It is demonstrative for the progressive and centrifugally oil-spot-like extension of the lesion and might explain the round-shape of the small lesions which stop their extension without any morphological correlations.

Adult↗
PubMed1978

Epidemiologic survey of multiple sclerosis in the Bucharest city and suburban area.

Epidemiologic survey over a restricted area of Romanian territory, i.e. the city of Bucharest with a population of 1,934,052 and a surface of 605 km2, established the following values for the MS parameters studied. On January 5, 1977 the prevalence rate for "probable" and "possible" cases was 46.4 per 100,000 inhabitants and for "probable" cases alone (with certain clinical diagnosis) 41.3 per 100,000. The specific 20- to 60-year age adjusted prevalence rate was 79.4 per 100,000. The incidence rate over the 1969--1976 period was 1.78 per 100,000. The prevalence and incidence rates in this survey are similar to those reported for two other large urban centers of Romania (population over 100,000 each), Romania being therefore situated in a geographical area of "high risk" for MS. The 0.61 per 100,000 nationwide and the 0.65 per 100,000 Bucharest mortality rates are lower than those reported in other geographical areas of "high risk" for MS.

Adolescent↗
PubMed1975

The effect of ATP on lactic dehydrogenase (LDH) activity and influenza B virus multiplication.

The authors investigated the effect of ATP, an energy supplying substance, on the activity of LDH, an enzyme of the glycolytic pathway and on the multiplication of influenza virus strain B/Singapore in embryonate hen eggs. In the presence of ATP the increase in LDH activity could be detected from the first 1-3 hours and became obvious after 24 hours; likewise, virus multiplication was more intensive so that the hemagglutinating (HA) activity appeared 12 hours earlier than in controls and the increased HA values persisted for a longer time. The isoenzymatic pattern showed an intensification of LDH4 and LDH5 fractions in virus-inoculated eggs.

Adenosine Triphosphate↗
PubMed1975

Variations in the activTY OF SOME BRAIN AND PLASMA ENZYMES UNDER THE INFLUENCE OF +Gz acceleration.

The present paper refers to the activity of some enzymes associated with the cellular cytomembranes in the plasma and brain of guinea pigs exposed to the action of repeated +10Gz acceleration. Immediately after the last run, diminution of enzymatic activity in the brain supernate ran parralel to a rise in plasma enzymatic activity. Variations in enzymatic activity suggested the liberation of enzymes connected with the neuronal organelles, perhaps consequent to alterations in the permeability or structure of the neuronal cytomembranes. These alterations might also be interpreted as being accompanied by permeabilization of the blood-brain barrier, with release of enzymes from the neuronal structures into the plasma. Changes in the permeability of the neuronal membranes might be attributed to several factors: cerebral hypoxia following the hemodynamic and ventilation alterations induced by hypergravitation, the influence upon the membrane permeability of hormones released in excess under the stress of acceleration, and the strain to which the central nervous system neurones are subjected by the multitude of afferent impulses with a starting point in the various types of receptors stimulated by hypergravitation.

Acceleration↗