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Biomedical subjects

A Galli

Publications and source records attributed to A Galli.

At least 127 records · Page 7Linked to original sources
PubMed1992

Mutagenicity of methyl methanesulfonate and cyclophosphamide in resting and growing Saccharomyces cerevisiae D7 cells.

In order to evaluate the optimal experimental conditions and to identify the best growth phase for yeast genotoxicity studies, comparative experiments were performed with stationary and growing cells. Methyl methanesulfonate (MMS) and cyclophosphamide (CP) were used as chemical mutagens and strain D7 of Saccharomyces cerevisiae as detector of induced mitotic gene conversion (trp+ convertants) and point reverse mutation (ilv+ revertants) in log or stationary phase cells after either 4 or 16 h of treatment. The highest MMS-induced toxicity and genotoxicity were observed after 16 h of exposure in a suspension test with log phase cells, which is consistent with the greater permeability and sensitivity of growing yeast cells. The maximal induction of genetic effects and toxicity by CP was conversely obtained after 16 h of treatment in stationary phase cells. This may be ascribed to the greater ability of detoxication of growing cells as compared to resting cells. Our results suggest that in evaluating the mutagenicity of chemicals in yeast systems it is important to consider factors such as growth phase and exposure time.

Cyclophosphamide↗
PubMed1992

Somatostatin release is enhanced in the hippocampus of partially and fully kindled rats.

The release of somatostatin (somatostatin-like immunoreactivity) from hippocampal slices during the development of hippocampal kindling in rats was measured under resting and depolarizing conditions. Preliminary experiments in naive rats showed that the spontaneous efflux of somatostatin (4.0 +/- 0.3 fmol/ml every 10 min) was independent of external Ca2+ but was reduced to 71.5 +/- 6% of baseline (P < 0.05) during 20 min incubation with 5 microM tetrodotoxin. Neuronal depolarization with 25, 50 and 100 mM KCl induced a Ca(2+)-dependent somatostatin release, respectively 4.3 +/- 0.4, 16.7 +/- 1.6 and 22.0 +/- 1.3 times baseline (P < 0.01). Veratridine caused a dose-dependent Ca2+ and tetrodotoxin (5 microM) sensitive release ranging from 6.5 +/- 0.1 to 13.0 +/- 1.4 times baseline at 1.4 microM and 50 microM respectively (P < 0.01). One week after the last of three consecutive stage 5 seizures (full seizure expression) or 48 h after the last stage 2 stimulation (preconvulsive stage), 50 mM KCl-induced somatostatin release was significantly higher (1.8 +/- 0.1, P < 0.01) than in shams (animals implanted with electrodes but not stimulated) in the stimulated and contralateral hippocampus. Somatostatin release measured under resting conditions was increased by 1.5 times in the stimulated hippocampus at stage 2 (P < 0.05) and by 2.2 and 1.7 times in both hippocampi at stage 5 (P < 0.01). Forty-eight hours after the induction of a single afterdischarge no significant changes were found in either spontaneous or 50 mM KCl-induced release of somatostatin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Effect of firing rate on the calcium permeability in adult neurons during spontaneous action potentials.

Calcium channels in neurons mediate a wide variety of essential functions. In addition to contributing to action potential shape, they furnish a substrate that acts as an intracellular second messenger. This study shows that the shape of the neuronal action potential has characteristics that promote long openings of L-type (high threshold) calcium channels. We also present evidence that a change in the firing rate of isolated neurons modulates gating of single calcium channels. This mechanism could be important in modulating neuron excitability and providing a rise in intracellular Ca, when needed.

Action Potentials↗
PubMed1992

Specificity and protective activity of murine monoclonal antibodies directed against the capsular polysaccharide of type III group B streptococci.

We have obtained 41 monoclonal antibodies directed against type III group B streptococci by immunizing Balb/c mice with formalin-killed bacteria. All of these antibodies reacted with purified type-specific carbohydrate by enzyme-linked immunosorbent assay and immunoprecipitation tests. The epitope recognized by all of these antibodies was associated with terminal sialic acid residues, as indicated by abrogation of immune reactions by treatment of the type-specific carbohydrate with neuraminidase. Two purified monoclonal antibodies (the IgM P9D8 and the IgG3 P4F12) were further characterized for their protective activity in a neonatal rat model of infection. P9D8 and P4F12 antibodies were significantly protective when administered in a dose of 0.5 and 2.5 mg/kg, respectively, at the same time as 3 x 10(5) colony forming units of type III streptococci. Protection was still observed when the antibodies were given up to 9 h after challenge. No protection was afforded against infections with type Ia/c and II streptococci. Similarly, both antibodies effectively opsonized type III, but not Ia, Ib or II bacteria, in an in vitro assay. These and similar, previously described, monoclonal antibodies may be useful, possibly after "humanization" by genetic engineering, for the therapy of neonatal group B streptococcal infections.

Animals↗
PubMed1992

Long-term evaluation of the abdominal wall competence after total and selective harvesting of the rectus abdominis muscle.

Fifty patients who underwent unilateral breast reconstruction by transverse rectus abdominis musculocutaneous flap transposition between January 1987 and December 1989 are the object of this study. Every patient underwent selective harvesting of the medial portion of the muscle, whereas the lateral strip was left in place and studied intraoperatively by selective stimulation of the ninth intercostal motor nerve before closure of the fascial defect. Two separate ecographic scans of the abdominal wall were performed respectively 7 days and 6 months postoperatively, to evaluate the diameters of the residual portion of the rectus muscle and its long-term evolution. Our results show that in a considerable number of patients, the lateral strip of rectus was denervated at surgery. Long-term ecographic scans demonstrate, however, that in spite of this finding, the residual muscle usually maintains its diameters, thus significantly contributing to the competence of the abdominal wall, at least from the static point of view.

Abdominal Muscles↗
PubMed1992

Filtration and local synthesis of lacrimal proteins in acquired immunodeficiency syndrome.

In AIDS the onset of the ocular dry syndrome, characterized by lacrimal hyposecretion and deterioration of the corneal and conjunctival epithelium, generally accompanies the clinical aggravation of immunodepression. The study of serum and lacrimal proteins contributes to our knowledge of the pathophysiology of this syndrome. The lacrimal clearance of albumin indicates changes in the permeability of the haemato-lacrimal and conjunctival barrier. Lacrimal monomeric IgA and IgG are mainly of plasmatic origin, while polymeric IgA and IgM are synthesized in situ. The concentrations of these analytes thus reflect ocular humoral immune status. They show a strong humoral protein response in patients with cytomegalovirus retinitis. Lacrimal concentrations of lactoferrin and lysozyme were found to be significantly decreased in AIDS patients with ocular dryness, reflecting a decrease in the secretory activity of the lacrimal gland. Moreover, ocular lympho-plasmocyte infiltration was observed in several patients, with an increase in lacrimal beta 2-microglobulin concentrations. These various lacrimal proteins could be good markers of the ocular dry syndrome in AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1992

[The selection of resident physicians. The evaluation of their cardiology knowledge and of their pregraduate experience].

The purpose of this work was to assess the level of cardiological knowledge in a population of recently graduated physicians and to compare the examination results with pregraduation experiences. The results of the residency entrance examinations of 230 physicians from different universities were analyzed (Table 1). The examination consisted of 70 questions (69 by multiple choice and 1 of professional competence). The cardiovascular area was explored through 28 questions including basic and clinical subjects (Fig. 1). A qualitative and quantitative analysis of the examination was made based on difficulty and discrimination levels (Annex 1-2). A danger level was established when the answer involved a potential risk of death for the patient. Thirty percent of applicants passed the exam (60% of correct answers). Informative questions were easier than those of application and interpretation. A greater difficulty was evidenced with respect to questions in the clinical area (Fig. 3). A higher performance was noted in men, graduates from the University of Buenos Aires and those applicants with assistance and teaching experience. A remarkable positive correlation between average marks during the students career and the level of marks obtained in this exam (Fig. 2) was noted. Twenty-six percent of the physicians who failed gave potentially dangerous answers (Fig. 4). The examination results give us the opportunity to obtain information regarding features of university education.

Adult↗
PubMed1991

Thiokynurenates: a new group of antagonists of the glycine modulatory site of the NMDA receptor.

Several substituted derivatives of kynurenic acid were tested on the N-methyl-D-aspartate (NMDA) receptor/ion channel complex present in the guinea pig myenteric plexus, on the binding of [3H]glycine and of [3H]N-[1-(2-thienyl)cyclohexyl]piperidine [( 3H]TCP) to rat cortical membranes and on the depolarization of mice cortical wedges induced by NMDA or quisqualic acid (QA). Kynurenic acid derivatives, having a chlorine (CI) or a fluorine atom in position 5 or 7 but not in position 6 or 8 had significantly lower IC50s than the parent compound when tested on the antagonism of glutamate-induced ileal contraction and in the glycine binding assay. A further significant increase in potency was obtained by substituting a thio group for the hydroxy group in position 4 of kynurenic acid: the IC50 was 160 +/- 20 microM of kynurenic acid and 70 +/- 15 microM of thiokynurenic acid in the myenteric plexus whereas these IC50s for glycine binding were 25 +/- 3 and 9 +/- 2 microM respectively. Several thiokynurenic acid derivatives were synthetized and showed an increased affinity for the glycine recognition site over the corresponding kynurenic acid derivatives. Glycine competitively antagonized the actions of the thiokynurenates in the ileum, in cortical wedges and on [3H]TCP binding. In this preparation, 7-Cl-thiokynurenic acid had an IC50 of 8 microM for antagonizing 10 microM NMDA-induced depolarization while 50% of the 10 microM QA depolarization was antagonized at 300 microM. Thus thiokynurenic acid derivatives seem to be a new group of potent and selective antagonists of strychnine-insensitive glycine receptors.

Animals↗
PubMed1991

Genotoxicity of vanadium compounds in yeast and cultured mammalian cells.

The ability of vanadium compounds to induce genetic activity was investigated in D7 and D61M strains of Saccharomyces cerevisiae and in Chinese hamster V79 cell line. In our previous work, ammonium metavanadate (pentavalent form, V5) induced mitotic gene conversion and point reverse mutation in the D7 strain of yeast. The genotoxicity was reduced by the presence of S9 fraction, which probably reduced pentavalent vanadium to the tetravalent form. In the present study, vanadyl sulfate (tetravalent form, V4) induced no convertants and revertants in yeast cells harvested from stationary growth phase. With yeast cells from logarithmic growth phase, which contain high levels of cytochrome P-450, a significant increase in genetic effects was observed. Further experiments, performed by treating cells harvested from logarithmic growth phase in the presence of cytochrome P-450 inhibitors, indicated that the monooxygenase system influenced the genotoxicity of metavanadate while the genetic activity of vanadyl remained unaffected. Aneuploidy effect in the D61M strain of Saccharomyces cerevisiae was induced by either V5 or V4, confirming that vanadium compounds are potentially antitubulin agents in eukaryotic cells. Although these compounds are very toxic in V79 cells, no mutagenic effect was observed in the presence or in the absence of S9 fraction.

Animals↗
PubMed1991

Effectiveness of 1,2,3,4-tetrahydro-9-aminoacridine (THA) as a pretreatment drug for protection of mice from acute diisopropylfluorophosphate (DFP) intoxication.

The protective action of 1,2,3,4-tetrahydro-9-aminoacridine (THA) against acute diisopropylfluorophosphate (DFP) intoxication was evaluated in mice by measuring the effects of the pretreatment of the animals with various doses of the drug on the DFP LD50. In the same experiments, the action of physostigmine and pyridostigmine were compared. THA at the doses 2.5, 5 and 7.5 mg/kg injected subcutaneously 15 min before DFP caused a dose-dependent increase in the DFP LD50, resulting in protection ratios equal to 3, 3.1 and 4.4, respectively, in the absence of atropine and 4.5, 8.6 and 14.5, respectively, in the absence of atropine and 4.5, 8.6 and 14.5, respectively, in the presence of atropine sulfate (17.4 mg/kg) therapy. Under the same experimental conditions, the protective ratios of 0.1 mg/kg physostigmine and pyridostigmine were 2.2 and 1.3, respectively, without atropine and 11.0 and 12.2, respectively, with atropine. The effectiveness of THA antidotal effect was inversely correlated to the time between pretreatment and DFP administration, being maximal when THA was injected 15 min before poisoning. In separate experiments, the time-course of acetylcholinesterase (AChE; EC 3.1.1.7) activity recovery was evaluated in the whole brain and diaphragm tissues of mice pretreated with THA (5 mg/kg) and physostigmine (0.1 mg/kg) 15 min before poisoning with DFP (8 mg/kg). At 10 min after DFP administration residual AChE activity in the brain averaged 4, 25 and 15% of that in controls in the animals pretreated with atropine alone, atropine plus THA or atropine plus physostigmine, respectively. At 24 h after poisoning, brain AChE activity averaged 34 and 47% of that in controls in the mice protected by THA and physostigmine, respectively. As for the diaphragm, AChE activity in THA-pretreated animals was 29% of controls 10 min after poisoning versus 8 and 23% in unprotected and physostigmine-pretreated animals, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

A systematic aesthetic approach to primary closure of the donor site following transposition of vertical forehead flaps.

Twenty patients underwent transposition of a vertical forehead flap to correct defects of the middle third of the face. The treatment and results are reported and evaluated. Based of the width of the secondary forehead defect, the best technique of direct closure was determined. Simpler cases were resolved by careful application of the basic techniques of plastic surgery--undermining and scalp flap rotation. When a forehead defect larger than 4.5 cm was expected, previous forehead skin expansion seemed advisable. A primary, tension-free suture of the forehead defect was achieved in every case, thus significantly improving the aesthetic outcome of the operation.

Adult↗
PubMed1991

An improved approach for transformation of plant cells by microinjection: molecular and genetic analysis.

A new culture method for the injection of tobacco mesophyll protoplasts has been established. The protoplasts are embedded in a thin layer of alginate and are nourished from the medium in the underlying basis layer. In the alginate layer the protoplasts regenerate to calli at a frequency of up to 80%. Embedded protoplasts can be selected either with 50 mg l-1 kanamycin or 5 mg l-1 paromomycin. Single resistant cells can be recovered from about 10,000 sensitive cells in one alginate layer. Injection of the neo gene (coding for neomycin phosphotransferase II) into protoplast derived single cells in the alginate layer results in kanamycin resistant colonies that can be regenerated to mature plants. These plants express the neomycin phosphotransferase as shown by enzyme activity assay. The integration of the transgene into the plant genome could be proved by Southern hybridization to high molecular weight DNA. With this culture method 100 cells can be injected per hour. Transformation frequencies range from 2 to 20%. In crossing experiments, it was shown that the foreign gene is transmitted to the next generation in a Mendelian fashion.

Base Sequence↗
PubMed1991

Frozen bovine semen quality and bovine cervical mucus penetration test.

Research has been carried out to test bovine cervical mucus penetration (penetration) as a means for evaluating frozen-thawed bovine semen. A commercially available cervical mucus penetration test kit (the kit) was used. A total of 158 previously frozen semen samples collected from 61 bulls were thawed in a 37 C water-bath for 2 minutes. Four ways to estimate penetration were compared using the distance traveled during 90 minutes 1) at 21 C, or 2) at 37 C, by 3) the first solitary mobile spermatozoon, or by 4) the front of the mass of the mobile spermatozoa. Penetration was measured using phase contrast microscopy and a millimeter grid. Spermatozoal quality parameters (concentration, total motility, progressive motility, acrosome integrity, total sperm integrity and cytoplasmic droplets) were measured and the correlation to penetration was calculated. The best way to assay penetration with the kit was by measuring the penetration of the first solitary mobile spermatozoon at 37 C. Semen quality variability was significant (P < 0.05) relative to penetration. Linear correlations between penetration and acrosome integrity r=0.42 as well as between penetration and total sperm integrity r=0.53 were highly significant (P < 0.001). There was significant linear multiple regression between penetration and acrosome integrity (expressed as percentage and number) and total sperm integrity (expressed as percentage and number) (r=0.62; F=23.5147; P<0.0001). There was a significant difference between the average progressive motility of samples with penetration > 20 mm and samples with penetration </= 20 mm (30.5 vs 20.8; P </= 0.01). However there were semen samples (N = 8 123 ; 6.5%) with normal progressive motility (29.94 +/- 5.30) after thawing and low penetration (</= 20 mm). There was no linear correlation between penetration and fertility (60 days non-return percentage). Therefore the penetration can distinguish samples of frozen-thawed bovine semen with not good or good progressive motility (> 20%), but it is not useful to define the fertility level of semen samples.

Journal Article↗
PubMed1991

Micro-targeting: high efficiency gene transfer using a novel approach for the acceleration of micro-projectiles.

We have constructed a novel micro-projectile accelerating system for efficient gene transfer into cells in situ that avoids binding DNA to micro-projectiles and keeps the DNA in solution. Further, instead of a macro-projectile (or the equivalent), it accelerates the particles in a Bernoulli air stream. The micro-targeting approach directs highly dispersed particles to sites with diameters as little as 0.15 mm, allowing precise aiming to restricted tissues. The system is physically flexible and should therefore be adaptable to different tissues and species. Transient expression of the Escherichia coli beta-glucuronidase gene in immature wheat embryo scutella was obtained at a frequency of up to 3% of the treated cells in the surface layer. In tobacco SR1, we achieved many transgenic plants, and the efficiency of stable transformation with the neomycin phosphotransferase (NPTII) gene was approximately 10(-3) per exposed cell.

Cloning, Molecular↗
PubMed1991

Protection of acetylcholinesterase by meptazinol in mice exposed to di-isopropyl fluorophosphate. Comparison with physostigmine.

The protective action of meptazinol against acute di-isopropyl fluorophosphate (DFP) intoxication has been evaluated in mice by measuring the effects on the DFP LD50 of the pretreatment of the animals with increasing doses of the drug. Meptazinol at the doses 15, 30 and 45 mg kg-1 injected 15 min before DFP caused a dose-dependent increase in the DFP LD50, resulting in protection ratios equal to 2.1, 4.8 and 9.7, respectively, in the absence of atropine and 2.5, 4.7, and 8, respectively, in the presence of atropine sulphate (17.4 mg kg-1) therapy. Under the same experimental conditions, the protective ratio of 0.1 mg kg-1 physostigmine sulphate was 2.2 and 7.3 in the absence and presence of atropine therapy, respectively. In separate experiments, the time course of acetylcholinesterase (AChE) activity recovery was evaluated in the brain and diaphragm of mice pretreated with meptazinol (30 mg kg-1) or physostigmine (0.1 mg kg-1) 15 min before poisoning with DFP (8 mg kg-1). Ten minutes after poisoning, residual AChE activity in the brain averaged 4, 47 and 15% of that in controls in animals pretreated with atropine alone, atropine plus meptazinol or atropine plus physostigmine, respectively. Twenty four hours after poisoning, brain AChE activity averaged 31 and 47% of that in controls in mice protected by meptazinol and physostigmine, respectively. The data from the diaphragm closely paralleled those from the brain. It is concluded that high doses of meptazinol exert antidotal action against acute DFP poisoning in the mouse comparable in efficacy with that of physostigmine combined with atropine.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholinesterase↗
PubMed1990

Determination of O6-butylguanine in DNA by immunoaffinity extraction/gas chromatography-mass spectrometry.

A sensitive, specific, and rapid method for quantitating the minor adduct O6-butylguanine (O6BuG) in hydrolyzed DNA has been developed by combining immunoaffinity chromatography and high resolution gas chromatography-negative ion chemical ionization-mass spectrometry. Polyclonal antibodies raised against O6BuG were coupled to CNBr-activated Sepharose 4B and used for sample clean-up and extraction of the specific O6-alkylguanine. After addition of O6BuG and its deuterium labeled analogue (O6BuG-D7), used as internal standard, hydrolyzed DNA was applied on the immunoaffinity column and washed with water, and the immunoadsorbed butylated guanines were eluted with acetone/water cetome/water (95/5) before gas chromatographic derivatization. O6BuG and O6BuG-D7 were analyzed and quantitated by high resolution gas chromatography-negative ion chemical ionization-mass spectrometry as their pentafluorobenzyl-trimethylsilyl derivatives. Immunoaffinity column capacity and O6BuG recovery from this column were 1.53 nmol O6BuG/column and 62 +/- 5%, respectively. The method was applied to evaluate O6BuG levels in DNA butylated in vitro with 10 mM N-nitroso-Nr-butylurea or isolated from rats given an i.p. dose of 185 mg/kg N-nitroso-N-butylurea or N-nitrosodibutylamine. In the first case the level of modifications present in calf thymus DNA was 104 mumol O6BuG/mol guanine, and in the second case O6BuG in liver DNA was about 6 times higher after N-nitroso-N-butylurea (2.11 mumol O6BuG/mol guanine) than after N-nitrosodibutylamine (0.34 mumol O6BuG/mol guanine) treatment. These results indicate that O6BuG formed in vivo can be isolated and quantitated by this method, which may also be useful for studying DNA damage and repair mechanisms.

Animals↗