Search PubMed⌕ Search

Biomedical subjects

M A Calvo

Publications and source records attributed to M A Calvo.

At least 19 recordsLinked to original sources
PubMed1998

Intraocular pressure as a risk factor for visual field loss in pseudoexfoliative and in primary open-angle glaucoma.

OBJECTIVE: To analyze the relationship between intraocular pressure (IOP) and visual field loss in patients with primary open-angle glaucoma (POAG) and in those with pseudoexfoliative glaucoma (PEXG). DESIGN: A cross-sectional, observational study. PARTICIPANTS: Thirty-one patients with PEXG and 31 patients with POAG that was newly diagnosed were included in this study. MAIN OUTCOME MEASURES: The authors recorded the untreated IOP and the amount of the visual field loss, at presentation, in both study groups. RESULTS: The authors found a significant relationship between IOP and visual field mean deviation (MD) index (P = 0.0001, r = 0.68) in PEXG but not in POAG eyes (P = 0.7). CONCLUSION: The authors found that untreated IOP levels can explain the amount of visual field loss, as measured by the MD index, much better in patients with PEXG than in comparable patients with POAG. Thus, vulnerability of the optic nerve head to increased IOP appears to be different in these two diagnostic categories.

Aged↗
PubMed1998

Viscoelastic-injecting cystotome.

This continuous curvilinear capsulorhexis (CCC) technique is for use in complicated surgical cases such as when the anterior chamber is shallow, the red reflex is not good, or eye movements are present. This technique is easier and safer in such cases because it uses a cystotome connected to a viscoelastic syringe. First, the anterior chamber is filled with viscoelastic material using a conventional cannula. The cannula is replaced with a bent needle (or cystotome), and the CCC is performed in the usual way. This instrument allows the surgeon to inject small amounts of viscoelastic material exactly where and when it is needed. The anterior chamber remains deep while the CCC is performed, and the anterior capsule tear is done in a more controlled fashion.

Anterior Chamber↗
PubMed1998

[Human immunodeficiency virus and resistance].

It has been demonstrated that following prolonged treatment with reverse transcriptase inhibitors, especially with nucleoside analogs, resistant viral strains appear that show mutations in the nucleotides of the gene that codifies reverse transcriptase. These mutations cause changes in amino acids, which gradually increases resistance. In this study we evaluated the applicability af the LiPA HIV-1 RT test in determining the presence of mutations in this gene that can lead to resistance to antiretroviral treatments.Twenty-one samples were studied without previous knowledge of the antiviral treatments that the patients had received. No mutations in the HIV-1 stains from untreated patients were found. In the other patients who had undergone various treatment regimens, the results obtained With the LiPA HIV-1 RT made in possible to retrospectively identify the different nucleoside analogs they had been treated with. The most frequently found mutations were those that lead to a certain degree of resistance to AZT, followed by those related to resistance to ddl, which in effect in this order were the drugs used in the treatment of the patients. However, the LiPA HIV-1 RT test has certain limitations. It can only detect mutations that can be recognized by its sequences. As such, including sequences that would make it possible to study the possible genotypic variations in the gene that codifies the protease of HIV-1 would be helpful, given the importance of the protease inhibitors in clinical practice. In any case, direct sequencing continues to be standard method as it allows us to obtain full information on the genes that need to be studied.

Anti-HIV Agents↗
PubMed1997

Ocular hypotensive effect of pilocarpine before and after argon laser trabeculoplasty.

PURPOSE: The purpose of this study was to compare the hypotensive response of human glaucomatous eyes to 1% pilocarpine solution before and after argon laser trabeculoplasty. METHODS: We designed a prospective, 'repeated measures' study comparing the ocular hypotensive effect of acutely administered 1% pilocarpine solution in 30 medically uncontrolled glaucomatous eyes, before and after argon laser trabeculoplasty. RESULTS: The pilocarpine-induced IOP decrease was 3.6 +/- 0.59 mmHg before argon laser trabeculoplasty, and 1.8 +/- 0.53 mmHg after laser therapy. In both instances, the pilocarpine hypotensive effect was significantly correlated with pretreatment IOP (p = 0.02, r = 0.41 before argon laser trabeculoplasty, and p = 0.003, r = 0.52 after argon laser trabeculoplasty). We built a 'repeated measurements ANCOVA' model, and found no statistically significant difference between the pilocarpine IOP lowering effect before and after argon laser trabeculoplasty (p = 0.4). CONCLUSION: Argon laser trabeculoplasty does not modify the IOP lowering effect of 1% pilocarpine solution.

Aged↗
PubMed1996

Influence of the culture medium on the inhibitory activity of Arthrinium strains.

Modifications in the antibiotic capacity of Arthrinium strains when they were developed in culture media of various compositions were studied. The culture media used were 2% malt extract agar, Czapek-Dox agar, Sabouraud dextrose agar, oatmeal agar, Yoshimura's medium, mixed medium of salts, modified phytone agar, malt extract-yeast extract agar, potato dextrose agar, and Wickerham's medium. The inhibition values were compared with those obtained when the strains were developed in Wickerham's medium. The media which enhanced the production of inhibitory substances were potato dextrose agar and 2% malt extract agar.

Anti-Bacterial Agents↗
PubMed1995

Increased susceptibility of microcytic red blood cells to in vitro oxidative stress.

Oxidative damage to erythrocytes in thalassaemia has been related to generation of free radicals by an excess of denaturated alpha- or beta-globin chains, intracellular iron overload and low concentration of normal haemoglobin (HGB). Two good indicators of such oxidative damage are the high red blood cell (RBC) malonyldialdehyde (MDA) production detected following exogenous oxidant stress and the decrease of pyrimidine 5'-nucleotidase (P5N), the most sensitive enzyme to SH-group damage in vivo. Conflicting data, however, have so far accumulated in the literature concerning differences in oxidative damage between the different forms of thalassaemia and iron deficiency anaemia (IDA). In the present study, oxidative susceptibility, as defined by the production of MDA in vitro and antioxidant capacity, as measured by the activity of RBC glutathione peroxidase (GPx), superoxide dismutase (SOD) and by reduced glutathione (GSH), have been studied in microcytic RBCs from patients with beta-thalassaemia trait, Spanish (delta beta) zero-thalassaemia heterozygotes (delta beta-thalassaemia trait) and iron deficiency anaemia (IDA). The results are consistent with the existence of significant differences in the severity and pattern of oxidative stress susceptibility between beta-thalassaemia trait (increased MDA production and higher SOD and GPx activities) and the other two forms of microcytosis (delta beta thalassaemia trait and IDA). Furthermore, the finding of normal P5' N activity in delta beta thalassaemia trait, gives further support to the less intense peroxidative environment of RBCs in this form of thalassaemia when compared to beta-thalassaemia trait, characterized by acquired RBC P5' N deficiency due to oxidative damage.

5'-Nucleotidase↗
PubMed1995

Chemical microanalysis of hyphae and conidia from Arthrinium aureum.

Analysis of the chemical composition of hyphae, conidia and chlamydospores of Arthrinium aureum enabled all sample constituents of > 23 kD molecular weight to be detected. Sulphur, chlorine, potassium and calcium were present in the hyphae and condia of A. aureum, and sulphur, potassium and calcium in the chlamydospores.

Calcium↗
PubMed1994

[Infectious external otitis: etiology in the Terrassa region, culture methods, and considerations on otomycosis].

The etiology of infections of the outer ear was studied in the area of Terrassa (Barcelona) over a six-year period (1987-1992). A total of 1419 samples of ear discharge were processed. Traditional culture media were used to isolate the microorganisms as well as a modified culture medium prepared by us (APA). Usual methods were used to identify the microorganisms. The results show Pseudomonas aeruginosa to be the most frequently isolated microorganism. 76.5% of the otitis studied were unimicrobial and the presence of moulds or yeast was noted in 6.9% of samples. Otomycosis (5.9%) is one of the major pathological processes of the outer ear, and Aspergillus niger is the prime causal agent.

Aspergillosis↗
PubMed1994

[Anatomopathologic changes in the testis following prolonged treatment with LHRH agonists. Experimental study in rats].

Presentation of a study conducted on 20 male Wistar rats treated for 3 months with Leuprolide (LHRH agonist). Analysis of pathophysiological testicular changes resulting from the treatment and extent of recovery at 3 months of therapy discontinuation, relating those changes to testosterone plasma levels in peripheral blood. Serum testosterone fell to 1.17 +/- 0.30 ng/ml in the treated group, shifting to figures overlapping with normal values within 3 months of discontinuing treatment. Such decreased testosterone levels translate into significant testicular histological damage. Three months after interruption of treatment there is nearly complete recovery of such damage, with just around 10% tubules without spermatozoa, with unchanged germinal line. We conclude that the marked suppression in testosterone levels caused by LHRH agonists translates into a significant degeneration of the seminiferous tubule, which appears to be reversible 3 months after treatment discontinuation.

Animals↗
PubMed1993

Effects of Ca2+ channel antagonists in guinea-pig normal and skinned gall bladder.

CaCl2 (0.01-50 mM, in K(+)-depolarized tissues), KCl (0.1-100 mM) and acetylcholine (1 nM-10 mM) produced concentration-dependent contractions of guinea-pig isolated gall bladder. Nifedipine (1-100 microM), verapamil (1-100 microM), diltiazem (1-100 microM), cinnarizine (1-100 microM), and flunarizine (1-100 microM) each produced a concentration-related inhibition of the log concentration-effect curve for CaCl2. The rank order of potencies of these antagonists, measured as the IC50 against Ca2+ (50 mM)-induced contraction of depolarized gall bladder, was diltiazem (0.25 microM) > or = verapamil (0.8 microM) approximately nifedipine (1.2 microM) >> cinnarizine (25 microM) approximately flunarizine (80 microM). Verapamil and diltiazem depressed KCl-induced contraction with an effectiveness and potency similar to those displayed against CaCl2 but nifedipine, cinnarizine and flunarizine were less effective against contractions in response to KCl compared to CaCl2. Verapamil and diltiazem, but not the other Ca2+ channel antagonists tested, had a specific inhibitory effect on the contractions due to KCl when compared to acetylcholine-induced contractions. Cinnarizine (10-100 microM) and flunarizine (10-100 microM), but not the other antagonists tested, depressed Ca2+ (20 microM)-evoked contraction of skinned guinea-pig gall bladder preparations. It is concluded that distinct differences exist between the Ca2+ channel antagonists examined. The action of nifedipine, verapamil and diltiazem is restricted to the plasmalemma whereas cinnarizine and flunarizine also act on the intracellular contractile apparatus.

Acetylcholine↗
PubMed1993

[Diagnostic value of aspiration cytology with ERCP].

ERCP is of great value in diagnosing malignant pathology of the biliopancreatic duct system. However, the ERCP endoscopic characteristics in malignant stenosis often lack specificity and are difficult to differentiate from those of chronic pancreatitis. In these cases histological confirmation is essential to diagnosis. With the aim of increasing the diagnostic possibilities of ERCP in pancreatic cancer--particularly when associated with chronic pancreatitis--we performed aspiration cytology of pancreatic juice obtained via endoscopic cannulation of the main pancreatic duct using ERCP in 102 patients with suspected periampullar pathology, chronic pancreatitis and/or pancreatic cancer. The diagnostic sensitivity of cytology for pancreatic malignancy was 33.3%, versus 60% for cancer of Vater's papilla. Specificity was 100% in both cancers. We observed no false positive results or complications. On combining both techniques, i.e., ERCP and cytology of the pancreatic juice, sensitivity increased to 100% for pancreatic malignancy, 77.7% for chronic pancreatitis (characteristic ERCP radiographic images and absence of neoplastic cells) and 100% in the case of ampullomas. Difficulties in the differential diagnosis between advanced chronic pancreatitis and pancreatic cancer persist with ERCP alone. In such cases aspiration cytology may secure a definitive diagnosis--particularly when neoplastic cells are demonstrated (Class IV).

Adult↗