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Biomedical subjects

R Ortiz

Publications and source records attributed to R Ortiz.

At least 73 records · Page 4Linked to original sources
PubMed1990

Fibroblast behavior at aqueous interfaces with perfluorocarbon, silicone, and fluorosilicone liquids.

Perfluorocarbon, silicone, and fluorosilicone liquids with potential for use as vitreous substitutes in the management of complex retinal detachment were evaluated for surface reactivity by assessing the behavior of anchorage-dependent fibroblasts plated at the phase boundary between these compounds and culture medium. Low-viscosity perfluorcarbons were alumina-treated to remove polar impurities. On perfluorodecalin, perfluorodimethylcyclohexane, perfluorotrimethylcyclohexane, perfluoroethylcyclohexane, perfluorooctane, perfluoroperhydrophenanthrene, perfluoromethyladamantane, perfluorodimethyladamantane, the highly viscous perfluoropolyether liquids Krytox TLF7067 and 6354, and dimethylsiloxane liquids of a variety of viscosities, most cells did not attach; the few that did attach exhibited minimal spreading behavior and did not achieve the flattened spindle-shape morphology which is a prerequisite to normal proliferative activity. Conversely, on perfluoromethyldecaline, perfluorofluorene, perfluorotributylamine, the perfluoropolyether K-6 hexamer, trifluoropropylmethylsiloxane (fluorosilicone), and diphenyldimethylsiloxane, some cells became fusiform-shaped and exhibited proliferation, the extent of which varied with the compound. The association of alumina treatment of perfluorocarbon liquids with a reduction in cell growth was indicative of a relationship between the presence of residual hydrogen-containing impurities and the capacity for cellular attachment and growth. This correlation was demonstrated also in experiments in which cell attachment and growth was facilitated by the addition of hydrogen-rich monohydroperfluorooctane to alumina-treated perfluorooctane. In conclusion, evidence for the presence of surface active impurities in liquid vitreous substitute materials can be obtained by observing the behavior of attachment-dependent cells plated at the boundary between these compounds and culture medium.

Aluminum Oxide↗
PubMed1989

Active and inactive forms of the transition-state analog protease inhibitor leupeptin: explanation of the observed slow binding of leupeptin to cathepsin B and papain.

Leupeptin and similar peptide argininal (arginine aldehyde) transition-state analog protease inhibitors exist in three covalent forms in aqueous solution, the leupeptin hydrate (IH), a cyclic carbinolamine form (IC) generated by the addition of the guanidino epsilon N to the aldehydic carbon, and the free aldehyde form (IA). 1H NMR in D2O show their equilibrium concentrations to be 42, 56, and 2% for IH, IC (R and S enantiomers), and IA. The rates of conversion of (formula; see text) were determined by 1H NMR in D2O by trapping IA with semicarbazide. Application of a deuterium isotope effect of 2.8 led to rate constants in H2O for kC of 0.092 min-1 and kD of 0.73 min-1. The equilibrium concentration of IA and rates for kC and kD are then used to explain the lag phase in the inhibition of cathepsin B and papain by leupeptin. Two circumstances are observed. (i) At micromolar concentrations of leupeptin and papain the binding of leupeptin is biphasic with rate constants identical to kD and kC. (ii) At more dilute nanomolar concentrations of total leupeptin and proteases, the observed lag phase for approach to steady-state inhibition (with rate constant k') is now explained by the low values of the koff rate constants (0.072 min-1 for cathepsin B and 0.024 min-1 for papain) together with the extremely low concentrations of the active inhibitor form IA, with k' = kon[IA] + koff. While kon[IA] is slow, the second-order rate constant kon is found to be quite fast, 1.2 x 10(7) M-1 s-1 for cathepsin B and 1.8 x 10(7) M-1 s-1 for papain. Thus, the binding of leupeptin to cathepsin B and papain may show a lag phase, but this is not due to slow binding.

Algorithms↗
PubMed1988

Perineal recurrence of adenocarcinoma of prostate following radiation therapy.

Two cases of seeding of adenocarcinoma of the prostate to the perineum via biopsy tract are presented. Both patients had been treated previously with external beam radiotherapy. The dose of radiation to the perineum was calculated and, in both cases, was not tumoricidal. Treatment options for this uncommon site of recurrence are presented.

Adenocarcinoma↗
PubMed1987

Experimental vitreous replacement with perfluorotributylamine.

Perfluorotributylamine, a liquid fluorochemical used in artificial blood substitution, was evaluated for potential application as a vitreous substitute having heavier density than saline. It was injected into the vitreous of 38 rabbit eyes after mechanical vitrectomy or gas compression of the vitreous with perfluoropropane. The eyes were observed for periods of up to five months. Clinically the liquid occupied the lower vitreous space but gradually dispersed into smaller fluorochemical droplets. In the upper vitreous clusters of cells appeared within three to four weeks which precipitated on the posterior lens surface and in the cortical vitreous. In eyes with experimental retinal detachment perfluorotributylamine had physical properties which provided mechanical retinal tamponade. Its interfacial tension prevented passage through iatrogenic retinal breaks. Histopathologic findings showed irregularly shaped defects in the outer segment disks as early as two days after vitreous replacement. These changes appeared to reverse if perfluorotributylamine was removed after two days. The cellular response in the vitreous consisted primarily of monocyte-derived macrophages capable of ingesting fluorochemical (foam cells).

Animals↗
PubMed1987

Ternary complexes of Cu(II) ion with cimetidine and L-alanine.

(Cu(CM)A)B(C6H5)4 and Cu(CM)A(OH) X H2O (CM = cimetidine and HA = L-alanine) were prepared and characterized by elemental analysis, TG-DTA, IR, and electronic spectral data and magnetic susceptibility measurements. The EPR spectrum of (Cu(CM)A)B(C6H5)4 shows a distorted octahedral environment for the Cu(II) ion.

Alanine↗
PubMed1987

Inorganic pyrophosphatase activity in cell-free extracts of Ureaplasma urealyticum.

Cell-free extracts of Ureaplasma urealyticum strains Pi and T960 (CX8) (serovars 6 and 8, respectively) metabolized inorganic pyrophosphate (PPi). The inorganic pyrophosphatase (PPase) activity was greatest with Mg2+ as cofactor, but Mn2+ acted as a poor substitute. The PPases of the two serovars differed electrophoretically. Although the highest PPase activity was obtained using PPi as substrate, the enzyme could also utilize to a lesser degree both tripolyphosphate and trimetaphosphate. No activity was observed against beta-glycerophosphate, naphthyl phosphates, glucose 6-phosphate, fructose 6-phosphate, fructose 1,6-bisphosphate, thiamin pyrophosphate, phosphoribosylpyrophosphate, ADP or ATP. Acid- and alkaline-phosphatase activities were observed with naphthyl phosphates as substrates, but they did not have the same electrophoretic mobility on gels as the PPase activity. U. urealyticum PPase was inhibited by oxidized glutathione, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, phenylglyoxal, p-chloromercuribenzoic acid, Mn2+, Zn2+ and Ca2+. Neither reduced glutathione, L-cysteine nor Co2+ enhanced activity. PPi can act as a substrate or regulator of certain metabolic reactions, and PPi metabolism can function in bacterial bioenergetics; its role in ureaplasmas is presently unclear.

Cations, Divalent↗
PubMed1987

Placental abnormalities in systemic lupus erythematosus: in situ deposition of antinuclear antibodies.

We studied 5 placentae from patients with systemic lupus erythematosus (SLE) for the presence of immunopathologic changes. We found antinuclear antibodies (ANA) deposited along the villi, trophoblast and amnion producing a lupus band-like pattern. The ANA were IgG class and had C3 fixing activity. Of the T cell subsets found in the placenta, OKT8 was the predominant type in patients with SLE and controls. All the patients were ANA positive, and 1 was also positive for anti-Ro(SSA). One newborn, positive for ANA and anti-Ro(SSA), developed neonatal lupus, 1 infant with a cardiac septal defect was ANA negative, and the other infants were normal. Our study demonstrates that in pregnant women with SLE, ANA deposition occurs in the placenta in situ.

Antibodies, Antinuclear↗
PubMed1987

Nail, skin, and scleral pigmentation induced by minocycline.

Minocycline-induced cutaneous and nail bed discoloration, although uncommon, should be closely watched for during treatment. The initial changes may be subtle and may mimic other processes that may deceive both patient and physician. Patients should be counseled about the remote possibility of pigmentation with the understanding that any such changes should resolve upon discontinuation of the drug. The time required for resolution depends upon the degree of pigmentation and may take longer than a year in extensive cases.

Eye Diseases↗
PubMed1986

Frequency of sister-chromatid exchange (SCE) in bone-marrow cells of severely malnourished animals during early life.

The frequency of sister-chromatid exchange (SCE) was examined in bone-marrow cells of 21-day-old Wistar rats malnourished during lactation and well-nourished controls of the same age. Malnutrition was obtained by increasing the litter size to 15 pups per mother. SCE were scored in 25 consecutive second-division metaphases in the femoral bone marrow cells from each animal. The average SCE in the malnourished animals was significantly higher than in the control group (p less than 0.01). The distribution of SCE per mitosis was also significantly higher in the malnourished animals (p less than 0.001). These results indicate that malnutrition per se during early life can increase SCE in the bone marrow of experimental animals.

Animals↗
PubMed1985

Post-weaning crowding induces corticoadrenal hyperreactivity in male mice.

The effect of various population densities on corticoadrenal function was studied in prepuberal male mice. High population densities decreased body weight gain. Neither adrenal weight nor basal serum corticosterone were modified by crowding. However, corticoadrenal response to some acute stresses such as noise and forced swimming was higher in crowded mice. As corticoadrenal response to adrenocorticotropin remained unaffected, it appears that crowding induced pituitary-adrenal hyperreactivity. Neither the defecation rate nor exploratory activity were altered by crowding, suggesting a dissociation between pituitary-adrenal responsiveness and behavioral measures presumably related to emotional arousal. These discrepancies may possibly be due to the higher sensitivity of corticoadrenal function to environmental changes. Our results suggest that crowding would be suitable as a model for chronic continuous stress.

Acute Disease↗
PubMed1984

Post-weaning differential housing and testosterone secretion in male mice.

The effect of different densities of animals per cage on basal testosterone secretion and its response to some stimuli was studied in prepuberal male mice. Mice housed with 110 or 55 cm2 of floor space per animal showed the same basal serum testosterone and hCG-induced testosterone release. Likewise, in a second experiment, the same basal serum testosterone and a similar response to acute noise stress were found in mice housed at 132, 66 or 22 cm2 of floor space per animal. These results suggest that post-weaning crowding did not affect Leydig cell function in male mice.

Adrenal Glands↗
PubMed1984

Effect of crowding on some physiological and behavioral variables in adult male rats.

The effect of two population densities on body weight gain, food and water intake and the weight of some organs and glands was studied in adult male rats. Behavioral reactivity to open field was also assessed. Crowded rats (10 animals per cage) showed lower body weight gain than control rats (3 per cage) throughout all the experimental period. Crowding decreased food intake and increased water intake. Any effect of crowding on the weight of thymus, liver and endocrine glands (except testes) was found. Open field defecation and activity were the same in control and crowded rats. Discrepancies from earlier works could likely be due to methodological differences and these are discussed in the text.

Animals↗
PubMed1984

Cell proliferation in bone marrow cells of severely malnourished animals.

The cell proliferation of bone marrow cells in rats, suffering from severe malnutrition during the lactation period, was investigated by using bromodeoxyuridine (BdUr) mixed with 100 mg of activated charcoal injected i.p. The undernourished rats had significantly more mitosis in the first generation (82.6%) than did well-nourished rats (44.6%) at 18 hours after the BdUr injection, whereas there were more cells in second division metaphase in the well-nourished (54.7%) than in the undernourished group (13.7%). Our results seem to indicate that malnutrition produces a prolongation in the time of proliferation of bone marrow cells during the lactation period. This agrees with other reports that used other cell systems in experimental animals and severely malnourished children.

Animals↗
PubMed1983

Corticoadrenal and behavioral response to open field in pairs of male rats either familiar or non-familiar to each other.

The effect of the presence either of a familiar or non-familiar conspecific animal on serum corticosterone and some behavioral responses in the open field was studied in male Sprague-Dawley rats. Animals tested in presence of a familiar animal showed a higher corticosterone response and a higher defecation rate. It suggests that rats experienced more emotional reactivity in presence of a familiar animal than in presence of a non-familiar one. Time spent in social interaction was higher in non-familiar pairs; however, ambulation and rearing were lower, suggesting competition between social investigation and novel environment exploration.

Adrenal Cortex↗
PubMed1978

Heterogeneity of hereditary methaemoglobinaemia: a study of 4 Cuban families with NADH-Methaemoglobin reductase deficiency including a new variant (Santiago de Cuba variant).

NADH-methaemoglobin reductase deficiency has been found in 4 Cuban families; 3 subjects carried the mild form of the deficiency while in 2 sibs of the fourth family the deficiency was associated with neurological involvement. The parents in this family were consanguinous and the sibs were shown to be homozygous for a new fast electrophoretic variant. It was named Diaphorase Santiago de Cuba.

Adolescent↗