Biomedical subjects
Publications and source records attributed to O Ruiz.
CASE REPORT: We present the case of a 27-year old woman suffering from a chorioretinal inflammatory disease that was diagnosed as punctate inner choroidopathy (PIC) after a complete ophthalmic evaluation. DISCUSSION: PIC must be taken into consideration when evaluating a patient with a white dot syndrome.
PURPOSE: To investigate the demographic characteristics, clinical findings and long-term outcome of central serous chorioretinopathy (CSC). METHODS: This study examined retrospectively the clinical stories and fluorescein angiographies of 113 patients with CSC and a minimum follow-up of 12 months. RESULTS: A total of 113 patients was examined; 90 were men and 23 women. Bilateral involvement was found in 13 cases. In 85.7% of the eyes (Group I) resolution was completed in months and mean final visual acuity (VA) was 79.3/100, while 14.3% of the eyes (Group II) showed a chronic evolution, with diffuse retinal pigment epithelipathy and mean final VA of 47.2/100. The mean age of the patients in Group II was significantly higher; male:female ratio was also higher in this Group. Bilateral involvement occurred in 6% of patients from Group I and in 46.6% in Group II. CONCLUSIONS: Chronic CSC affected less than 15% of the patients. Mean age in this group of patients was higher than in patients with a classic CSC, most of the cases were men, bilateral involvement was present in nearly 50% of the cases and 50% of them suffered a significant visual permanent impairment.
PURPOSE: To study the effectiveness of Yag capsulotomy, therapeutic vitreal aspiration and intravitreal injection of antibiotics combination on the treatment of chronic postoperative endophthalmitis. METHODS: Six patients with symptoms of refractory postoperative endophthalmitis after extracapsular cataract extraction, with an intraocular lens were treated following a protocol that included: YAG capsulotomy, vitreal aspiration and intravitreal injection of antibiotics. RESULTS: In four cases -66%- the micro-organism was isolated -three cases of coagulase- negative staphylococci and one case Corynebacterium spp. In all the cases the inflammatory process decreased, and a noticeable improvement of visual acuity was achieved. No recurrent cases were observed (two patients died before the end of the study). CONCLUSIONS: As way of conclusion we can state that the initial capsulotomy allows the destruction of the infection reservoir in order to eradicate the agent. This endophthalmitis therapeutic alternative is effective, easy and reliable for the ophthalmologist.
In some trained athletes, maximal exercise ventilation is believed to be constrained by expiratory flow limitation (FL). Using the negative expiratory pressure method, we assessed whether FL was reached during a progressive maximal exercise test in 10 male competition cyclists. The cyclists reached an average maximal O2 consumption of 72 ml. kg-1. min-1 (range: 67-82 ml. kg-1. min-1) and ventilation of 147 l/min (range: 122-180 l/min) (88% of preexercise maximal voluntary ventilation in 15 s). In nine subjects, FL was absent at all levels of exercise (i.e., expiratory flow increased with negative expiratory pressure over the entire tidal volume range). One subject, the oldest in the group, exhibited FL during peak exercise. The group end-expiratory lung volume (EELV) decreased during light-to-moderate exercise by 13% (range: 5-33%) of forced vital capacity but increased as maximal exercise was approached. EELV at peak exercise and at rest were not significantly different. The end-inspiratory lung volume increased progressively throughout the exercise test. The conclusions reached are as follows: 1) most well-trained young cyclists do not reach FL even during maximal exercise, and, hence, mechanical ventilatory constraint does not limit their aerobic exercise capacity, and 2) in absence of FL, EELV decreases initially but increases during heavy exercise.
The green fluorescent protein of Aequorea victoria (GFP) is a natural peptide chromophore without substrate or cofactor requirements for fluorescence. In vitro, a recombinant F64L/S65T GFP mutant (GFPmut1) exhibited pH sensitive fluorescence within the physiologic range. When heterologously expressed in BS-C-1 cells or rabbit proximal tubule cells, uniform cytosolic and nuclear fluorescence was observed. Cytosolic fluorescence constituted over 80% of the total. Excitation scanning of transfected cells revealed two GFPmut1-specific regions that were pH-sensitive over the physiologic range, and each region exhibited a unique pH "bias" in fluorescence emission. Excitation at or near the expected maximum of 488 nm (region II) uniformly resulted in fluorescence that was preferentially altered at acidic pH. In contrast, a novel "wild-type" excitation peak at 400 nm (region I) resulted in alkaline-biased fluorescence similar to that described for the wild-type chromophore in vitro, suggesting that wild-type spectral features disrupted in vitro by mutagenesis may be recovered in intact cells. Calibration of intracellular pH (pHi) with in situ fluorescence following excitation in either region revealed a semilogarithmic relationship between fluorescence intensity and pH within the physiologic range. We therefore measured pHi changes attributable to altered Na/HCO3 cotransport (NBC) activity both in GFPmut1-expressing cells and in paired untransfected cells loaded with BCECF. Basal NBC activity was the same in each group, as was the stimulation of activity by 10% CO2, thus validating the utility of GFPmut1 as a fluorescent probe for pHi and establishing a novel, useful, and practical application for GFPmut1 in monitoring pHi in real time.
The effect of several methylputrescines on the activity of insulin-induced ornithine decarboxylase (ODC) was examined in H-35 hepatoma cells. The induction involved both protein and m-RNA synthesis. Actinomycin D inhibited ODC activity when given up to 1 h after insulin treatment. When added to the medium 2 h or 3 h after the insulin, the activity was increased 100% and 80% respectively. Insulin-induced ODC from H-35 cells had a biphasic half-life, a shorter one of 46 min and a longer one of 90 min. 1-Methylputrescine and 2-methylputrescine were found to be competitive inhibitors of the ODC from H-35 cells with Ki values of 2.8 and 0.1 mM respectively. Putrescine itself was found to have a Ki = 2.4 mM. N-Methylputrescine was a very poor inhibitor of the cell free ODC while 1,4-dimethylputrescine did not show any inhibitory effect. When cellular ODC activity was measured, the four methylputrescines assayed as well as putrescine entirely abolished its activity in the H-35 cells when given at a 1 mM concentration together with insulin. 1-Methylputrescine and 1,4-dimethylputrescine abolished 60% of the activity at a 0.1 microM concentration. All the methylputrescines given at 0.1 mM concentrations decreased the putrescine content of the stimulated cells to the levels found in quiescent cells, but only 1-methyl and 2-methylputrescines decreased spermidine and spermine content. 1,4-Dimethyl and 1-methylputrescines showed a strong inhibition of ODC synthesis, while the other diamines were less inhibitory. At concentrations that abolished ODC activity, 1,4-dimethylputrescine decreased 70% of the total immunoreactive ODC bands, while 1-methyl and 2-methylputrescine decreased them by 50%, and N-methylputrescine and putrescine decreased them by 20%. The lack of decrease in immuno-reactive ODC with the latter two compounds was mainly due to the appearance of immunoreactive degradation products of ODC of low molecular weight. Putrescine and N-methylputrescine affected protein synthesis to a small extent in stimulated cells, while 1-methylputrescine decreased it to the level of non-stimulated cells. Insulin (1 microM concentration) stimulated DNA synthesis in the cells, and this stimulation was doubled in the presence of 2-methylputrescine or putrescine. It can be concluded that, among the methylputrescines assayed, 2-methylputrescine was the best inhibitor of cell-free ODC activity, while 1,4-dimethylputrescine and 1-methylputrescine were the best inhibitors of cellular ODC activity.
1,4-Dimethylputrescine (2,5-hexanediamine) was separated into its racemic and meso isomers by fractional crystallization of its dibenzoyl derivative. The racemic form was resolved into its (+)- and (-)-isomers with (+)- and (-)-dibenzoyltartaric acids. None of the three isomers (meso, +, and -) inhibited ornithine decarboxylase (ODC) activity in vitro, while all the three were strongly inhibitory of ODC when assayed in vivo in rats or in H-35 hepatoma cells. In rat liver the three isomers also decreased the putrescine pool while only the (+)-isomer decreased spermidine content. In the H-35 cells the (-)- and (+)-isomers decreased the spermidine and spermine content. When ODC was induced in the latter by insulin it was found that the (-)-isomer strongly inhibited protein and ODC synthesis, while the (+)-isomer and the meso isomer were less inhibitory. The meso isomer was a good inducer of ODC antizyme in rat liver, while the (+)- and (-)-isomers were poor inducers of the former.
The inhibitory effect of a series of 2-alkylputrescines on rat liver and Escherichia coli ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17) was examined. At 2.5 mM concentrations, 2-methyl-, 2-propyl-, 2-butyl-, 2-pentyl- and 2-hexylputrescines were stronger inhibitors of the mammalian enzyme than putrescine. Only the higher homologues (from 2-propyl- to 2-hexylputrescine) were inhibitors of the E. coli enzyme. An analysis of the effect of increasing concentrations of the 2-alkylputrescines showed that the main difference in the behaviour of the mammalian and E. coli decarboxylases toward 2-alkylputrescines was that the former was strongly inhibited by 2-methylputrescine whereas the latter was not. 2-Alkylputrescines were found to be competitive inhibitors of both the bacterial and mammalian enzyme. The smallest Ki values (0.1 and 0.5 mM) were found for the 2-hexyl- and 2-pentylputresciens. N-Methyl-, N-ethyl-, N-propyl- and N-butylputrescines (50 mumol per 100 g body weight) were assayed as inhibitors of thioacetamide-induced rat liver ornithine decarboxylase. N-Propylputrescine was found to be the most inhibitory (66% inhibition) and although the N-alkylputrescines were taken up by the liver, they did not inhibit the liver polyamine pools. Both putrescine and N-methylputrescine were found to stabilize the thioacetamide-induced ornithine decarboxylase at the onset of the enzyme's degradation, while 2-alkylputrescines were inhibitory under similar conditions. N-Methylputrescine induced antizyme in thioacetamide-treated rats. In thioacetamide- or dexamethasone-treated rats, 2-methylputrescine was found to be the strongest in vivo inhibitor of the liver decarboxylase. Although 2-alkylputrescines were efficiently taken up by the liver, they did not noticeably inhibit its polyamine pools. 2-methylputrescine decreased the putrescine concentration of the liver, but not its spermidine and spermine content. No induction of ornithine decarboxylase antizyme by 2-methylputrescine could be detected. The intrahepatic concentration of the latter decreased with time, very likely due to its degradation by a diamine oxidase, since the decrease was inhibited by aminoguanidine.
N-Methyl-, N-ethyl-, N-propyl- and N-butylputrescine were assayed as substrates of diamine oxidase from pea seedling and pig kidney. With the exception of N-methylputrescine they were found to be oxidized to the corresponding aminoaldehydes. 1-Methyl-, 2-methyl-, 1-ethyl- and 1-propylputrescine were oxidized by the oxidases at lower rates than the N-alkylderivatives. 1,3-Dimethylputrescine had negligible oxidation rates while 1,4-dimethylputrescine (2,5-diaminohexane) was not a substrate. The oxidation of putrescine by the kidney oxidase was inhibited by 1,4-dimethylputrescine, while the pea oxidase was strongly inhibited by the former as well as by 2-methylputrescine and 1,3-dimethylputrescine. Serum amine oxidase did not oxidize the substituted putrescines although several of the latter inhibited spermidine oxidation by this oxidase.
N-Methyl-, N-ethyl-, N-propyl-, N-butyl-, N,N-dimethyl- and N,N'-dimethylputrescines were assayed as inhibitors of ornithine decarboxylase (EC 4.1.1.17) from rat liver and from Escherichia coli. They were found to be poor inhibitors, with the exception of N-propylputrescine and N,N-dimethylputrescine, which were inhibitory at 25 mM. A homologous series of 1-alkylputrescines ranging from 1-methylputrescine (1,4-diaminopentane) to 1-heptylputrescine (1,4-diaminoundecane) was assayed for effect on the activity of ornithine decarboxylase from the same sources. 1-Methylputrescine (5 mM) inhibited the mammalian enzyme, while the higher homologues showed significantly less inhibitory activity. When assayed on the bacterial enzyme, 1-methylputrescine (5 mM) was not inhibitory, while the higher homologues showed inhibitory effects. At higher concentrations, 1-methylputrescine and 1-heptylputrescine were the best inhibitors of these series of rat liver ornithine decarboxylase. When 1-methylputrescine, 2-methylputrescine, 1,2-dimethylputrescine, 1,3-dimethylputrescine and 1,4-dimethylputrescine were assayed as inhibitors of the decarboxylase, 2-methylputrescine was found to be the best inhibitor of the rat liver enzyme, while 1,3-dimethylputrescine was the best inhibitor of the bacterial enzyme. 1,4-Dimethylputrescine (2,5-diaminohexane) did not inhibit the enzyme from either source. Both, 2-methylputrescine and 1-methylputrescine, as well as the 1,2- and 1,3-dimethylputrescines were competitive inhibitors of the enzyme, and a Ki of 1 mM was obtained for 2-methylputrescine when the rat liver decarboxylase was used. N-Methyl, 1-methyl and 2-methylputrescines were found to inhibit in vivo the activity of rat liver ornithine decarboxylase which had been previously induced by thioacetamide treatment. 2-Methylputrescine (50 mumol/100 g body weight) was found to be the best in vivo inhibitor (93% inhibition), while putrescine under similar conditions inhibited 56% of the enzymatic activity.
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Phagocytosis was evaluated in nine patients with splenctomy undergoing renal transplant, eight renal transplanted patients without splenectomy, three immunodepressed patients with terminal renal failure, four patients with splenectomy and six healthy volunteers. For phagocytosis evaluation, neutrophils adhered to glass were used. They were cover with 4% latex and albumin containing culture medium with or without phagocytosis stimulating tetrapeptide extracted from IgG in each case. Phagocytosis was decreased in all groups studied. Immunodepressed patients showed the highest diminishment of phagocytosis and patients with splenectomy and immunodepression the lesser. It was speculated that such a finding is due to a decrease of tetrapeptide in serum.
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Both filtering surgery with Mitomycin-C and diode laser cyclophotocoagulation have proved to be effective alternatives in cases of glaucoma with poor surgical prognosis. The right eyes of 40 pigmented rabbits were randomly divided into 2 groups: Mitomycin-C group underwent filtering surgery with application of 0.4 mg/ml of Mitomycin-C whereas the diode laser (DL) group received 15 applications of 1.8 J (1800 mW. 1000 ms) distributed in 270 degrees. Mean IOP showed statistical differences in two periods between days 3-13 and 45-60-Mann-Whitney U test -with a higher IOP lowering in the DL group. The comparison of IOP survival curves (Log-Rank test) was not significant p = 0.070809. Ocular hypertension, hyphema and inflammatory signs were higher in the DL group, both in short and long term, but in terms of statistical significance only ocular hypertension showed differences p = 0.00011717-Fisher exact test. Microscopic examination revealed patent sclerostomies in 60% of the MMC group eyes with different grades of fibroblastic proliferation. In the DL group we observed necrosis of the scleral stroma and of the pigmented and unpigmented ciliary epithelium, with signs of thermal coagulation of the ciliary stroma and of the stromal vasculature. We must point out that the treatment with laser has proved to be more effective although both treatments showed very acceptable IOP lowering until 2 months after the surgery.
In the present work, we used capillary zone electrophoresis (CZE) for the analysis of Vitamin C and inorganic cations (potassium, sodium, calcium, and magnesium) in lettuce (Lactuca sativa) during postharvest storage. The leaves of the creasphead lettuce samples were treated with 18 M omega water for cation analysis and, alternatively, with 3% wt/vol oxalic acid solution for ascorbic acid extraction. They were then homogenized and centrifuged, and the supernatants were introduced into the capillary for CE analysis. The cation analysis was performed on an uncoated fused-silica capillary column of 75 microns i.d. and 50 cm total length, using 15 mM creatinine, 15 mM alpha-hydroxyisobutyric acid, acetic acid, pH 4.00, as running buffer at an applied voltage of 20 kV. Indirect on-line UV detection was carried out at 214 nm. The content of Vitamin C was measured using an uncoated fused-silica capillary column of 50 microns i.d. and 45 cm total length; 10 mM sodium tetraborate, 10 mM sodium biphosphate, pH 9.00, as background electrolyte at an applied voltage of 20 kV. On-line UV detection was achieved at 254 nm.
BACKGROUND: The genetic and molecular mechanisms involved in antimicrobial resistance of 10 strains of gramnegative bacilli (1 Serratia marcescens; 2 Escherichia coli; 1 Proteus mirabilis; 4 Klebsiella pneumoniae; 1 Enterobacter cloacae y 1 Alcaligenes faecalis), isolated from adult patients with nosocomial pulmonary infection at the in-patient facilities of the University Hospital of Los Andes, Mérida, Venezuela, have been studied. METHODS: The antimicrobial susceptibility was determined by minimum inhibitory concentrations using the dilution method in agar. The study of extrachromosomal genes was carried out by conjugation, bacterial infection with the bacteriophage M13 and curing of plasmid by acridine orange. The plasmids were isolated by alkaline lysis and analysis of restriction endonuclease digestion was carried out separately using the enzymes EcoRI and HindIII. A DNA probe, derived from the region which encodes the TEM-1 beta-lactamase of the plasmid pBR322 was used for dot-blot hybridization tests. RESULTS: All of the gramnegative bacilli showed resistance to ampicillin, carbenicillin and cephalothin (> 128 micrograms/ml) and 3 strains also showed resistance to gentamicin (> 64 micrograms/ml). Genetic and molecular procedures showed the presence of conjugative plasmids of approximately 54 kb in all the 10 strains. The restriction patterns obtained by using EcoRI and HindIII indicated common DNA fragments in most of the plasmids studied. The dot-blot hybridization tests confirmed homology between the plasmids and the DNA probe used (TEM-1 beta-lactamase). CONCLUSIONS: In this study, the gramnegative bacteria of nosocomial origin harbored self-transferable plasmids of approximately 54 kb, which mediate resistance to gentamicin and encode a beta-lactamase of the TEM group.
A reproducible, rapid procedure for the determination of homocysteine, cysteine, and glutathione in human blood by micellar electrokinetic chromatography (MEKC) has been developed. Whole blood samples were deproteinized and centrifuged, and the supernatant was directly introduced into the capillary for analysis without further derivatization. Separations were performed using an uncoated capillary of 30 cm effective length and 50 microns i.d.; 20 mM phosphate, 20 mM borate, and 50 mM SDS, pH 9.00, as running buffer; and an applied voltage of 18 kV. On-line detection was carried out at 214 nm.