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Biomedical subjects

A Ortega

Publications and source records attributed to A Ortega.

At least 217 records · Page 12Linked to original sources
PubMed1984

Cholesterol effect on enzyme activity of the sarcolemmal (Ca2+ + Mg2+)-ATPase from cardiac muscle.

The effect of cholesterol incorporation and depletion of the cardiac sarcolemmal sacs on (Ca2+ + Mg2+)-ATPase activity was examined. Cholesterol incorporation to the sarcolemmal sacs was achieved utilizing an in vivo and an in vitro procedure. Cholesterol depleted membranes were obtained in vitro after incubation of the sarcolemmal sacs with inactivated plasma. Arrhenius plots of the (Ca2+ + Mg2+)-ATPase activity showed a triphasic curve when the assays were carried out using a temperature range between 0 and 40 degrees C. The sarcolemmal (Ca2+ + Mg2+)-ATPase activity was shown to be inversely proportional to the cholesterol concentration of the membranes, showing a low ATPase activity with a high cholesterol content and a high ATPase activity when the cholesterol concentration was low. Although the (Ca2+ + Mg2+)-ATPase activity was found to be inhibited in the cholesterol incorporated sarcolemmal sacs, the withdrawal of small amounts of cholesterol from the membranes produced an important stimulatory effect. Changes in (Ca2+ + Mg2+)-ATPase activity due to variation in the membrane cholesterol concentration were shown to be reversible. Our results indicate the possibility of a slow exchange of cholesterol between the tightly bound lipid surrounding the (Ca2+ + Mg2+)-ATPase and the bulk lipid of the sarcolemma.

Animals↗
PubMed1982

Subacute myelo-optic neuropathy (SMON). First neuro-pathological report outside Japan.

A 72-year-old Caucasian woman developed degeneration of the spinal cord long tracts, polyneuropathy, and optic atrophy after chronic ingestion of clioquinol (200 mg/day) since she was 45. Diseases with a similar clinical picture, notably vitamin B12 deficiency (B12D), and subacute myelo-optic neuropathy (SMON), are discussed with regard to the pathologic findings. In our patient findings were different from those reported in B12D, but similar to those in SMON. If, as we believe, our patient was suffering from the same disease as the SMON described by Japanese authors, this is the first case reported outside Japan in which pathological verification has been obtained.

Aged↗
PubMed1981

[Hepatic angiosarcomas].

The authors describe three cases of hepatic angiosarcoma diagnosed at postmortem examination, two of them being associated to thorium dioxide. The low incidence of these tumors amongst the general population is commented upon, and an update is made on the factors involved in their appearance, with special mention of thorium dioxide. An analysis of the clinical picture of the disease is undertaken, emphasizing its diagnostic difficulties. A tentative diagnosis can be made on the basis of clear-cut epidemiological data and or the presence of increased radiological density over the liver, spleen and paraaortic lymph nodes in the cases associated to thorium dioxide. Two of the reported patients presented hemolytic anemia, and disseminated intravascular coagulation, respectively; these findings, although nonspecific, may suggest the diagnosis in the presence of a toxic clinical picture or one of the above mentioned factors. The diagnosis should be made by the usual techniques utilized clinically to detect space occupying lesions within the liver. The evolution of such patients is rapidly progressive, with a fatal outcome within three to six months after beginning of symptoms.

Aged↗
PubMedDate not supplied

The removal of strontium from the mouse by chelating agents.

The effects of the chelating agents monosodium glutamate, Tiron, tartaric acid, ascorbic acid, 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6), 2,3-dimercaptosuccinic acid (DMSA), succinic acid, malic acid, ethylendiaminetetraacetic acid (EDTA), ethylenglycol-bis-(beta-amino-ethylether)-N,N'tetraacetic acid (EGTA), cyclohexane-diaminetetraacetic acid (CDTA) and diethylentria-minepentaacetic acid (DTPA) on the distribution and excretion of intraperitoneally injected strontium were investigated in male Swiss mice. Strontium nitrate was given at a dose equal to 3.78 mmol/kg and ten minutes after, chelators were administered intraperitoneally at doses approximately equal to one-fourth of their respective LD50 values. DTPA, followed by CDTA, EDTA and tartaric acid, was consistently the most effective in increasing the urinary excretion of strontium. Only ascorbic acid increased significantly the fecal excretion of strontium. CDTA, DTPA and ascorbic acid were also the most effective chelators in reducing the concentration of strontium found in various tissues. CDTA, DTPA and tartaric acid are the most effective agents of those tested in the removal of strontium after a single administration.

Animals↗
PubMedDate not supplied

Mucormycosis and ameloblastoma of the upper jaw.

We report a case of mucormycotic infection complicating a clinically silent ameloblastoma in an aged diabetic woman. Diagnosis was made by culture and biopsy of the affected tissue, where foreign-body granulomas were seen, an unusual inflammatory response for mucormycosis. A good outcome was achieved on the basis of radical surgery and amphotericin B infusion.

Aged↗
PubMedDate not supplied

Computed tomography in supratentorial hemangioblastoma.

Supratentorial hemangioblastomas are rare. A 28-yr-old man with a solid tumor in the left temporal region is described. There was neither meningeal connection nor associated polycythemia or Von Hippel-Lindau disease. Contrast enhanced computerized tomography showed a hyperdense, homogeneous lesion and cerebral angiography demonstrated a nodular tumor blush. The microscopic appearance of the lesion is described with a review of previously reported cases.

Adult↗
PubMedDate not supplied

Post-radiation cranial malignant fibrous histiocytoma studied by CT.

A 37-year-old woman presented with a proven case of malignant fibrous histiocytoma of the skull. This is thought to be a rare complication of post-radiation to a chromophobe adenoma which was treated by radiotherapy nine years previously. The radiation dose given to the sella region after the removal of the chromophobe adenoma was 4500 cGy.

Adenoma, Chromophobe↗
PubMedDate not supplied

Quantitation of intratumoral thymidylate synthase expression predicts for resistance to protracted infusion of 5-fluorouracil and weekly leucovorin in disseminated colorectal cancers: preliminary report from an ongoing trial.

A clinical trial for patients with measurable, disseminated colorectal cancer is being conducted to determine: (1) if intratumoral expression of thymidylate synthase (TS) affects response to protracted-infusion 5-fluorouracil (5FU); and (2) whether intratumoral expression of TS increases when clinical resistance is found after response to 5-FU. Polymerase chain reaction technology is employed to determine TS expression. Using beta-actin as an internal standard, TS expressions for 26 patients range from 0.5 x 10(-3) to 22.6 x 10(-3). Currently, 22 patients are evaluable for response and TS quantitation of their measurable tumour. 8 patients (36%) have had partial responses; 3 responding patients had been previously treated with 5-FU. A strong statistical association between TS expression and resistance to therapy has been found (P = 0.004). No patient with TS expression of 4.0 x 10(-3) or greater has responded. On average, patients previously treated with 5-FU have slightly higher levels of TS expression in their measurable tumours (P = 0.4). Whether responding patients will develop increased expressions of TS upon clinical progression of their cancer remains to be determined. Confirmation of these results in a larger cohort could lead to a scientific rationale for deciding upon specific therapy for patients with disseminated colorectal cancers.

Adult↗
PubMedDate not supplied

Toxicity of sediments from Bahía de Chetumal, México, as assessed by hepatic EROD induction and histology in nile tilapia Oreochromis niloticus.

The effect of environmental pollutants present in sediments obtained from Bahía de Chetumal, a bay on the border between Mexico and Belize, was studied in nile tilapia (Oreochromis niloticus) intraperitoneally injected with sediment extracts from six different sites of the Bay. Sediment samples used for the study contained a variety of organic chemicals such as organochlorine pesticides, polychlorinated biphenyls (PCBs) and polynuclear aromatic hydrocarbons (PAHs). Total cytochrome P-450 and EROD activity were measured in fish liver. Haematological and histological analyses were also carried out. Hepatic P-450 content in treated fish increased from 43 to 240%, and EROD activity from 85 to 160% compared to controls. Extracts from two sampling sites inhibited EROD activity. There were positive significant correlations between P-450 content and the levels of PCBs 44 and 128. EROD activity correlated to HCB, op'-DDE, pp'-DDE, pp'-DDD, mirex and PCB 18 concentrations. Blood examination showed cell degeneration and binucleated leukocytes with abnormal chromatin. Extract treatment also resulted in foci of hyperplasia on the basement of gill lamellae, hypertrophy and oedema in gills and liver necrosis. Control fish showed no abnormalities. The results demonstrate that sediments from Bahía of Chetumal have the potential to cause histopathological, haematological and biochemical alterations in fish. The administration of sediment extracts to fish may serve as a useful test to screen the toxicity of sediments from different areas.

Animals↗