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Biomedical subjects

J Monti

Publications and source records attributed to J Monti.

At least 19 recordsLinked to original sources
PubMed2001

Glial angiotensinogen regulates brain angiotensin II receptors in transgenic rats TGR(ASrAOGEN).

TGR(ASrAOGEN)680, a newly developed transgenic rat line with specific downregulation of astroglial synthesis of angiotensinogen, exhibits decreased brain angiotensinogen content associated with a mild diabetes insipidus and lower blood pressure. Autoradiographic experiments were performed on TGR(ASrAOGEN) (TG) and Sprague-Dawley (SD) control rats to quantify AT(1) and AT(2) receptor-binding sites in different brain nuclei and circumventricular organs. Dose-response curves for drinking response to intracerebroventricular injections of ANG II were compared between SD and TG rats. In most of the regions inside the blood-brain barrier [paraventricular nucleus (PVN), piriform cortex, lateral olfactory tract (LOT), and lateral preoptic area (LPO)], AT(1) receptor binding (sensitive to CV-11974) was significantly higher in TG compared with SD. In contrast, in the circumventricular organs investigated [subfornical organ (SFO) and area postrema], AT(1) receptor binding was significantly lower in TG. AT(2) receptors (binding sensitive to PD-123319) were detected at similar levels in the inferior olive (IO) of both strains. Angiotensin-binding sites sensitive to both CV-11974 and PD-123319 were detected in the LPO of SD rats and specifically upregulated in LOT, IO, and most notably PVN and SFO of TG. The dose-response curve for water intake after intracerebroventricular injections showed a higher sensitivity to ANG II of TG (EC(50) = 3.1 ng) compared with SD (EC(50) = 11.2 ng), strongly suggesting that the upregulation of AT(1) receptors inside the blood-brain barrier of TG rats is functional. Finally, we showed that downregulation of angiotensinogen synthesized by astroglial cells differentially regulates angiotensin receptor subtypes inside the brain and in circumventricular organs.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed2001

Alterations in blood pressure and heart rate variability in transgenic rats with low brain angiotensinogen.

To study whether the brain renin-angiotensin system plays a role in the long-term and short-term control of blood pressure and heart rate variability, we examined in transgenic rats [TGR(ASrAOGEN)] with low brain angiotensinogen levels the 24-hour variation of blood pressure and heart rate. Telemetry recordings were made during basal and hypertensive conditions induced by a low-dose subcutaneous infusion of angiotensin II for 7 days. Short-term blood pressure and heart rate variability were evaluated by spectral analysis, and as a measure of baroreflex sensitivity, the average transfer gain between the pressure and heart rate variations was calculated. During the angiotensin II infusion in control but not TGR(ASrAOGEN) rats, the 24-hour rhythm of blood pressure was inverted (5.8+/-2 versus -0.4+/-1.8 mm Hg/group of day-night differences of blood pressure, P<0.05, respectively). In both the control and TGR(ASrAOGEN) rats, the 24-hour heart rate rhythms remained unaltered and paralleled those of locomotor activity. The transfer gain between 0.3 to 0.6 Hz was significantly higher in TGR(ASrAOGEN) than in control rats during control (0.71+/-0.1 versus 0.35+/-0.06, P<0.05) but not during angiotensin II infusion (0.6+/-0.07 versus 0.4+/-0.1, P>0.05). These results demonstrate that the brain renin-angiotensin system plays an important role in mediating the effects of angiotensin II on the circadian variation of blood pressure. Furthermore, these data indicate that a permanent deficiency in the brain renin-angiotensin system alters the reflex control of heart rate in rats.

Angiotensin II↗
PubMed2001

Expression analysis using oligonucleotide microarrays in mice lacking bradykinin type 2 receptors.

We recently conducted detailed cardiovascular and blood pressure-related phenotypic studies of mice lacking the bradykinin-B(2) receptor and were unable to identify a phenotype despite insensitivity to infused bradykinin. We therefore used oligonucleotide microarray analysis of some 12 000 genes and expressed sequence tags to identify molecular mechanisms that might be involved in compensating for the lack of a functional B(2) receptor in the kidneys of the mice. We identified 2 gene families that may have an impact on cardiovascular regulation and the bradykinin pathway. A water transport channel in the kidney, AQP4, was downregulated in the mice, whereas other members of the gene family did not show differences in expression levels. In addition, a number of serine proteases were upregulated in B(2) receptor-deficient mice. These genes are all located within a gene cluster on mouse chromosome 7. The findings were verified by an independent method. We suggest that microarray analysis has usefulness in elucidating otherwise unappreciated compensatory signaling pathways.

Animals↗
PubMed2000

A 3-dimensional model building by homology of the HFE protein: molecular consequences and application to antibody development.

Genetic hemochromatosis (GH) is a common inherited disease of iron metabolism affecting 2-5 in 1000 individuals of European origin. A candidate gene for GH, namely HFE has been recently characterized. Structural studies of the protein product of the HFE gene are of major interest for a better understanding of the molecular physiopathology in iron overload. We have built a 3-dimensional model of the HFE protein based on congruent with40% homology of sequence identity with HLA-Aw68, another MHC class I molecule. This work presents the first 3-dimensional structure of HFE available in the public domain (http://swift.embl-heidelberg.de/service/francois). The 3-dimensional characteristics of the protein complexed with the beta2-microglobulin are presented. The model has been used to predict immunogenic loops and to develop an antibody able to recognize a protein exhibiting the same molecular weight as HFE. Structural consequences of two common mutations are debated and evolutionary hypotheses are considered in the discussion of the particular biological activity of HFE. This study shows that a strategy based on homology modeling is sufficient to undertake biological investigations.

Amino Acid Sequence↗
PubMed2000

Nitric oxide release and enhancement of lipid peroxidation in regenerating rat liver.

BACKGROUND/AIMS: Clarification of the role of lipid peroxidation in the onset of liver proliferation has been hampered by the fact that both higher and lower lipid peroxidation have been reported after two-thirds partial hepatectomy. Recently, it has been shown that nitric oxide might be involved in the control of early responses after partial hepatectomy. We analysed the possible involvement of nitric oxide production in lipid peroxidation levels during liver regeneration. METHODS: Sham-operated, hepatectomised and sham and hepatectomised rats pretreated with two inhibitors of oxide nitric synthesis (aminoguanidine or N(G)-monomethyl-L-arginine) were used throughout. Animals were killed at 1, 3, 5 and 15 h after surgery. Cytosolic superoxide dismutase and microsomal-lysosomal catalase activities were measured. Lipid peroxidation levels were measured as thiobarbituric acid-reactive substances and conjugated dienes. Cytosolic nitrate (a stable metabolic product of nitric oxide) was enzymatically determined. Inducible-type nitric oxide synthase (iNOS) was analysed in hepatic cytosol by immunoblotting. DNA synthesis 24 and 48 h after surgery was assessed by [3H]thymidine incorporation. RESULTS: Increased lipid peroxidation was found in total homogenate, cytosol and microsomes. The hepatic cytosolic content of nitrates increased, reaching the highest values at 5 h posthepatectomy. Aminoguanidine or N(G)-monomethyl-L-arginine pretreatment blocked the rise of nitric oxide production and lipid peroxidation levels and decreased the DNA synthesis. The increase in hepatic iNOS protein expression at 5 h after partial hepatectomy disappeared with aminoguanidine pretreatment. CONCLUSIONS: Our experiments suggest that nitric oxide plays a role in the proliferation mechanism, although it is responsible, at least in part, for the enhanced lipid peroxidation.

Animals↗
PubMed1999

[Drug therapy for prognostic improvement after acute myocardial infarct].

This review article summarizes the long-term standard therapy for patients with myocardial infarction. The chronic therapy is able to significantly improve quality of life and survival of affected patients. Previous studies showed that in most western countries, the established standard therapy is not given to all patients who would benefit from chronic treatment. The essential parts of today's myocardial infarction treatment consists of effective beta-blockade, inhibition of the angiotensin-conversion enzyme, inhibition of platelet aggregation and lipid lowering agents. This article reviews the clinical benefits which may be expected from each of these therapeutic approaches. Newer, but not yet proven strategies, like blockade of the angiotensin receptor subtype 1 and treatment with antioxidative agents will be discussed.

Adrenergic beta-Antagonists↗
PubMed1999

Diffusing capacity limitations of the extent of lung volume reduction surgery in an animal model of emphysema.

OBJECTIVE: The purpose of this study was to investigate in an elastase-induced emphysema rabbit model the effects of increasing resection volumes during lung volume reduction surgery on pulmonary compliance, forced expiratory air flow, and diffusing capacity to assess factors limiting optimal resection. METHODS: Emphysema was induced in 68 New Zealand White rabbits with 15,000 units of aerosolized elastase. Static respiratory system compliance, forced expiratory flow, and single-breath diffusing capacity were measured before the induction of emphysema, after the induction of emphysema, and 1 week after a bilateral upper and middle lobe lung volume reduction operation. RESULTS: Static respiratory system compliance with 60 mL insufflation above functional residual capacity increased with emphysema induction and then decreased progressively with resection of larger volumes of lung tissue (P =.001 by analysis of variance). Expiratory flow improved after lung resection in the rabbits with large resection volumes. In contrast, diffusing capacity tended to deteriorate with larger resection volumes (P =. 18). CONCLUSION: Improvements in respiratory system compliance and forced expiratory flow after lung volume reduction operations may account for the improvements seen clinically. Declines in diffusing capacity with extensive lung reduction may limit the clinical benefits associated with greater tissue resection volumes. Future investigations with animal models may reveal other physiologic parameters that may further guide optimal lung volume reduction procedures.

Animals↗
PubMed1999

[Detection of Helicobacter pylori by polymerase reaction in bile samples from gallbladder and bile stones].

Some papers report helicobacter pylori existence in bile from surgical specimens obtained during gallbladder or bile ducts surgery. The aim of this work was search by PCR, H. Pylori presence in bile specimens from patients suffering of gallbladder stones or by bile ducts stones. Bile samples were obtained by gallbladder punction during cholecystectomy in 26 patients, 19 of them with gallbladder stones and 7 also with gallbladder stones and bile duct stones. Age ranged from 22-69 years old, median 49.6 years old. Samples were sent to specialized biomolecular laboratory to perform PCR techniques. Two of 26 patients (7.6%) had positive reaction for the presence of DNA of H. Pylori in bile samples. Our research suggest that DNA of H. Pylori can be founded in bile samples patients with gallbladders and duct stones in Argentina.

Adult↗
PubMed1998

Risk factors associated with human cystic echinococcosis in Florida, Uruguay: results of a mass screening study using ultrasound and serology.

Sonographic evidence of asymptomatic Echinococcus granulosus lesions in the liver was found in 156 of 9,515 persons in the Department of Florida, Uruguay. The sensitivity of ELISA and latex agglutination serology compared with ultrasound was 47.6% and 28.1%, respectively, and specificity was > 85%. There was a significant positive association between positive sonography and a personal history of previous but treated Echinococcus infection while those that were seropositive but ultrasound-negative were significantly more likely to have a personal history of infection or a history of infection in their family. Prevalence of infection increased significantly with age. There was no correlation between echinococcosis and dog ownership or home slaughter of sheep but offal disposal was important, with an increased prevalence of infection of 3.2%, 2.8%, and 3.1%, respectively, in persons feeding offal to dogs or burying or burning it compared with a prevalence of 0.8-1.5% in those using other methods of disposal. Almost half the population, when questioned, seemed to have sound knowledge about E. granulosus and described correct treatment of E. granulosus in dogs but this did not affect prevalence. There was a significant positive association between infection and the presence of a fenced fruit/vegetable garden and use of rural waters, particularly the cachimba (a small dam) and the aljibe (a cistern or tank) that collect rainwater from the ground surface and roofs, respectively.

Adolescent↗
PubMed1998

[Helicobacter pylori detection by polymerase chain reaction in gastric juice and its correlation with the histology (Giemsa)].

HP infection is involved in the pathogenesis of several gastroduodenal diseases, as type B chronic gastritis, duodenal and gastric ulcer, MALT lymphoma and gastric cancer. The recent availability of molecular techniques, specifically the PCR, allow us to detect very low amounts of the bacterium. The aim of the study is to evaluate the presence of HP in gastric juice by PCR technique and to correlate this findings with histology (Giemsa) of gastric mucosa. Gastric juice PCR positive findings were found in 10/31 (32.3%) HP positive patients at histology. We concluded that HP in gastric juice is possible to detect by molecular techniques. In our study 32.3% of the patients showed the presence of HP in gastric juice.

Adult↗
PubMed1997

Principles of the surgical approach in human liver cystic echinococcosis.

Ultrasonography (USG) has recently contributed much to the diagnostic of hepatic cystic echinococcosis (CE). The use of portable ultrasonograph allowed us to perform a community survey among 9482 people living in a high risk area for CE in the Florida Department (Uruguay). Positive USG results were found in 123 asymptomatic patients. 48 out of 51 USG positive cases were surgically confirmed and 3 were found to be false positive. The results of this survey allowed us to propose a new classification of the echographic imaging based on the parasite's various evolutive and involutive stages. The Echinococcus granulosus cyst size was compared with the parasite's evolutive stages. The cyst's segmentary topography and the related risk of CE is evaluated. The importance of cystic-biliary communication is pointed out and its rational surgical treatment described. Finally, an algorithm is presented facilitating the choice of a rational treatment.

Adolescent↗
PubMed1996

[Reproducibility of nuclear grade in breast neoplasm. A multicenter experience].

Nuclear grade is considered a valuable prognostic factor in mammary carcinomas. Since the histological diagnosis of most of these tumors is made by "non expert" pathologists, it was considered interesting to find out the reproducibility of general pathologists to define the nuclear grade. In order to do this, a series of 15 mammary carcinomas, 10 of them randomly selected and 5 because they were considered difficult to classify for nuclear grade, were examined separately by 10 general pathologists. In a first round of observation, each one of them graded the cases according to their own criteria as used routinely, and for a second round they followed a written guide. An analysis of variance was applied to the data and no significant differences were found between observers, neither in the randomly selected cases nor in the total series. The written guide, surprisingly, instead of lowering the differences, increased them. Analysis of the individual performance of observers showed two of them having a great variation between both rounds of observation, and this was considered to influence the results of the whole group. Interobserver performance to discriminate high grade tumors (G3) from the rest, showed a good correlation in all the participants. These results allow us to conclude that in this series, examined by general pathologists, an acceptable reproducibility was observed, specially when high risk tumors were being identified.

Analysis of Variance↗
PubMed1996

Comparison of serodiagnostic tests and ultrasonography for cystic hydatidosis in an epidemiological study of rural Uruguay.

Cystic hydatidosis (CH) caused by Echinococcus granulosus is an important zoonosis worldwide. Several serodiagnostic and ultrasound tests are currently used for screening asymptomatic CH. The sensitivity of the serodiagnostic tests has been demonstrated by several groups to be lower than ultrasonography (US). To explain the mechanism of the difference in sensitivity, a large-scale US survey combined with an IgG4-enzyme-linked immunosorbent assay test was conducted in Uruguay. Our results suggest that certain cyst images, e.g., multivesicular cysts, may be closely associated with a high antibody response regardless of the cyst size, whereas other hydatid lesions, e.g., solid images with/without rolled parasite membranes, have lower antibody responses with a close relationship to cyst size. Seropositivity of subjects who had been treated surgically for removal of hydatid cysts in the last 5 yr was closest to that of actual CH patients, albeit free from CH by US. These findings are important for the proper use of serodiagnostic tests and US for community-based epidemiological studies.

Animals↗
PubMed1995

Ritanserin pharmacokinetics in abstinent chronic alcoholics.

Ritanserin is a thymosthenic agent with an extensive hepatic metabolism and long elimination half life in healthy volunteers. It has been used in abstinent chronic alcoholic patients showing an interesting performance in this condition. Ritanserin pharmacokinetics has only been evaluated in single dose healthy volunteer studies and, on the other hand, chronic use of the drug in alcoholic patients during withdrawal period could be anticipated. Therefore, the objective of the present study, is to assess the cumulating kinetics of the serotonin antagonist during chronic administration. Ten abstinent alcoholic patients were included in an open study. The drug was administered at a daily dose of 10 mg for 28 days and the active phase was preceded by a seven-day wash out period with placebo. Blood samples were taken on the 1st, and 28th, day of treatment, 24 hours after taking the drug. Urine samples were taken during the night before the second and 28th dose. Plasma and urine ritanserin concentration was measured by high performance liquid chromatography. Very large variations in initial and steady state concentrations (CV = 65 and 52% respectively) were found, which is reflected in the large variability of the calculated pharmacokinetic parameters. Ritanserin cumulation factor (R) was 6.9 +/- 8.3 (mean+SEM). Two patients showing extensive accumulation had prolonged elimination half lives (433 and 279 hours) that are explained mostly by an expansion of the volume of distribution and, to a lesser extent, by diminished clearance.

Adult↗
PubMed1985

[Acute cholecystitis and cancer of the gallbladder in the aged].

We are reporting 35 cases of gallbladder cancer in elderly people. 9 of them (25.7%) were operated with the diagnosis of acute cholecystitis. We point out the high incidence of the association of acute cholecystitis and gallbladder cancer, being the cholelithiasis a predominant factor in the pathogenesis of cancer. Considering that we found gallbladder cancer in 6.1% of the cholecystectomies, we advise to perform the surgical treatment in all the patients suffering of cholelithiasis.

Acute Disease↗
PubMed1980

[Gastric leiomyoblastoma].

Three cases of gastric leiomyoblastomas are presented (according to Stout's denomination) or epithelioid leiomyomas (according to Appelman). The subject is actualized and the low malignant potential of these tumors is pointed out. Leiomyoblastomas have to be classified among the leiomyomas (absolutely benign) and the leiomyosarcomas (malign). The lack of reliable criteria to determine the future of the patient is established, being the evolutive control the only way to make that clear. The mitotic counts--more than 5 for each 50 high-power dry objective field--is the most important isolated criterion to predict the probable malignancy of the lesion.

Female↗