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Biomedical subjects

F Teixeira

Publications and source records attributed to F Teixeira.

At least 73 records · Page 4Linked to original sources
PubMed1991

Medulloblastoma presenting as blindness of rapid evolution. A case report.

An 18-year-old man reported rapid decrease of visual acuity that progressed to total blindness in 1 month. Computed tomographic scanning showed two neoplastic masses: a large one, intra- and suprasellar, and a smaller cerebellar nodule. Histologically, the former proved to be a large metastasis of the small cerebellar medulloblastoma, which infiltrated and compressed the chiasm. Direct compression of the optic pathways by metastasis of a medulloblastoma is a rare event.

Adolescent↗
PubMed1990

Mechanism of action of doxepin in the treatment of chronic urticaria.

The present study examined 15 patients previously resistant to conventional antihistamines, in which doxepin at doses in the range of 50-75 mg/day was shown to be effective in treatment of chronic urticaria and without significant adverse side effects. However, some controversy remains about its mechanism of action in this particular disease. The aim of the present study was to examine the muscarinic, H1 and H2 blocking activity of doxepin. The following methods were used: a) gastric acid hypersecretion induced by histamine and carbachol in the pylorus-ligated rat preparation; b) contractile dose-response curves to histamine and carbachol in the guinea pig ileum; c) dimaprit-stimulated guinea pig atrium in vitro. pA2 values were determined for atropine, mepyramine, cimetidine and doxepin. As regards histamine, doxepin (50 mg/kg, po) increased gastric pH and decreased secretion volume, gastric acid concentration and total acid output; with carbachol, doxepin weakly antagonized those values. In the ileum, doxepin competitively antagonized carbachol (pA2 = 7.08) and histamine (pA2 = 9.72); pA2 values for atropine and mepyramine against carbachol and histamine were 9.11 and 8.82, respectively. In the atria, the dose-response curve to dimaprit was also competitively displaced by cimetidine (pA2 = 6.69) and doxepin (pA2 = 6.00). Doxepin displayed a very high affinity for H1 histamine receptor, being 8-fold more potent than mepyramine. Doxepin showed significant H2 blocking activity which was 5 times less potent than that of cimetidine. Doxepin competitively antagonized carbachol in the guinea pig ileum, and was 107 times less potent than atropine. The combined H1, H2 and muscarinic blocking activities of doxepin may contribute towards explaining its clinical efficacy in the treatment of chronic urticaria.

Adult↗
PubMed1990

Assessment of growth in sudden infant death syndrome.

Autopsy reports from 208 cases of sudden infant death syndrome (SIDS) were reviewed and divided into three groups: group 1, term infants without infection; group 2, term infants with mild infection, and group 3, premature infants. The brain weights of these children were matched by age and body length, separately for males and females, with reference values and a group of 53 children born at term who died from conditions that did not affect the central nervous system. The brains of children in groups 1 and 2 were heavier than reference values when matched by age and body length. The differences between group 1 and reference values tended to increase with age; however, when matched by body length, this tendency was no longer observed. Body lengths of SIDS cases at death were also greater than reference values. There was no difference between brain weights of children in groups 1 and 2. These data suggest that the enlarged brains were present from birth rather than the result of disproportionate postnatal growth. The cause of increased brain size in SIDS cases is unknown, as is its possible role in the events leading to sudden death.

Brain↗
PubMed1989

Chorea-acanthocytosis: report of a family and neuropathological study of two cases.

We report three siblings, offspring of normal consanguineous parents, with a progressive neurological illness that began in midlife and was characterized primarily by chorea and leading to death in the fourth decade. The proband had erythrocyte acanthocytosis with normal serum beta-lipoprotein. Biopsy of left gastrocnemius muscle showed neurogenic muscular atrophy. There was a decrease in the numbers of large myelinated axons of the sural nerve. Postmortem examination of two cases showed marked atrophy, neuronal loss and gliosis of the caudate nucleus and putamen. Autosomal recessive inheritance is likely in this family.

Acanthocytes↗
PubMed1988

Vascular changes in cutaneous neurofibromas.

A variety of vascular changes has been associated with neurofibromatosis, and morphological alterations of arteries have been described previously. However, little attention has been paid to structural modifications of the microvasculature in neurofibromas themselves. Small vessels of 10 cutaneous neurofibromas, excised from patients with neurofibromatosis, were studied by using transmission electron microscopy and compared with normal skin vessels. The major alterations were: (1) increased thickness of the cytoplasm of endothelial cells which send numerous long processes to the lumen and, in some instances, obliterate it; (2) larger numbers of endothelial cell processes on the abluminal surface which are apposed to pericyte processes; (3) increased amounts of filaments and free ribosomes in the cytoplasm of endothelial cells, and (4) abundant pericytes with bundles of cytoplasmic filaments and many small subplasmalemmal densities. Mitotic figures were not seen in any of the vascular elements. These changes were interpreted to be the result of a generalized malformative process of blood vessels in neurofibromas rather than a consequence of the action of a tumor angiogenesis factor.

Adolescent↗
PubMed1987

Piroxicam-induced photosensitivity.

During the last 3 years, 9 patients with a photosensitive eruption related to piroxicam therapy were seen. In all but one, it occurred within 4 days of first exposure to the drug. 7 patients required systemic corticosteroids, and 2 hospitalization. Clinical, histological and provocation studies were not conclusive in classifying the eruption as photoallergic or phototoxic. Experimental studies including photohaemolysis, Bacillus subtilis culture and nuclear magnetic resonance showed: (i) in irradiated piroxicam solutions, there was more haemolysis; (ii) in irradiated Petri dishes, piroxicam solutions showed greater inhibition of growth of B. subtilis; (iii) Piroxicam's NMR spectrum is not modified after irradiation. The results provide evidence of piroxicam phototoxic potential.

Adult↗
PubMed1986

Experimental rabies: ultrastructural quantitative analysis of the changes in the sciatic nerve.

To study the pathology of peripheral nerves in experimental rabies infection, street rabies virus ws inoculated into the right footpad of two groups of mice, A and B, which received, respectively, 10(4.5) LD50 and 10(3.5) LD50 of the virus. Paralysis was observed in 60% of animals of group A and 20% of group B. The main ultrastructural abnormality present in the sciatic nerves was degeneration of about 40% of myelinated axons. Only occasional unmyelinated axons were degenerated. Figures were similar for nerves of either side and for both groups. Frequency histograms of axonal diameter showed axons of all sizes to be altered in group A, whereas in group B there was tendency for larger axons to be damaged. Electron microscopy showed no typical bullet-shaped viral particles. Asymptomatic animals which received the higher dose of the inoculum showed a small (less than 1%) percentage of necrotic myelinated axons.

Animals↗
PubMed1981

Influence of deaminated metabolites on the relaxing effect of dopamine on dog saphenous vein.

The relaxing effect of dopamine was studied on the dog isolated saphenous vein contracted by prostaglandin F2alpha after alpha-adrenoceptor blockade by phentolamine. This effect is partially inhibited by propranolol and haloperidol suggesting that dopamine has two types of receptors in this vessel: beta- and dopaminergic receptors. However, the results obtained after treatment with drugs that interfere with deamination of catecholamines or after denervating the venous tissue led us to conclude that the agonist substance is not dopamine, but probably one of its deaminated metabolites or a secondary condensation product, namely tetrahydropapaveroline. Adrenaline has also been used to compare the behaviour of the two amines when interference in the deamination process is produced. The dissimilar results obtained with adrenaline are in good agreement with the hypothesis.

Animals↗
PubMed1980

The Twitcher mouse: an enzymatically authentic model of human globoid cell leukodystrophy (Krabbe disease).

The Twitcher is a new neurological mutant of mouse which shows clinical and histopathological features similar to those of human and canine globoid cell leukodystrophy (Krabbe disease). Brain and liver tissues of affected mice showed a profound deficiency of galactosylceramidase and lactosylceramidase I activities. A distinct group with intermediate enzyme activities could be identified among the phenotypically normal mice, consistent with their being heterozygotes. The Twitcher mouse is, therefore, not only a clinically and morphologically, but also an enzymatically, authentic model of human globoid cell leukodystrophy. This is the first enzymatically authentic murine model of human sphingolipidosis.

Animals↗
PubMed1980

Hereditary leucodystrophy in the mouse: the new mutant twitcher.

A new inherited neurological disease in the mouse (the mutant twitcher) has been studied. Transmission is by an autosomal recessive gene (twi). Affected animals are apparently normal at birth but develop a generalized tremor at about 3 weeks of age followed by progressive weakness and wasting. The disease is fatal by 3 months. The principal pathological changes affect the myelin of both central and peripheral nervous systems. Degeneration of myelin sheaths and the presence of multinucleated macrophages with PAS-positive cytoplasm are characteristic findings. Peripheral nerves show remyelination following demyelination. Electron microscopically the macrophages contain a variety of inclusions in which there are crystalline and multi-angular structures and twisted tubules. The abnormalities closely resemble those found in globoid cell leucodystrophy (Krabbe's disease) in man.

Animals↗
PubMed1979

[Spontaneous carotid-cavernous fistula: angiogammagraphic findings and computer analysis (author's transl)].

The case of a 74-year-old woman with a carotid-cavernous fistula is reported. She was admitted to hospital with oliguria and generalized edema. After improvement of the edematous condition she suddenly presented intense, pulsatile, frontal cephalea. It was more intense on the right side and was accompanied by nausea and vomiting and swelling of the right eye with reddening, sharp pains, difficulty of movement, and loss of vision. Cerebral angiogammagraphy was practiced in anterior-posterior and right lateral view. A righ carotid-cavernous fistula was discovered with drainage through the superior ophthalmic vein and the deep venous system. The angiogammagraphic findings can be considered characteristic; it is important to obtain activity/time curves from various areas of interest in order to evaluate the degree of shunting and the pathway of drainage from the fistula. There was a good coorelation with the arteriographic findings. Eight cases of carotid-cavernous fistulas diagnosed with radionuclids have been published previously, though the activity/time curves were not determined by computer for any of them.

Aged↗
PubMed1979

Binding of adrenaline and isoprenaline to plasma proteins of the dog.

Adrenaline was incubated with dog plasma in concentrations ranging from 50 to 1,000 ng/ml and binding to plasma proteins was found to be about 12% (8, 12 or 14%, as determined by spectrophotofluorimetric, liquid scintillation or Sephadex G-50 gel filtration methods, respectively). For isoprenaline, the binding to plasma proteins was of about 14-18%, as shown by liquid scintillation or Sephadex G-50 gel filtration methods. Cellulose acetate electrophoresis demonstrated that albumin does not play any significant role in this binding, in the case of both adrenaline and isoprenaline. These results show that adrenaline and isoprenaline are much less bound to proteins that noradrenaline (40%). It is concluded that the N substitution present in adrenaline and isoprenaline appears to be responsible for the different degrees of protein binding.

Animals↗
PubMed1978

Morphological patterns of the liver in South American blastomycosis.

Histological features were semi-quantitatively analysed in 60 livers, obtained by necropsy, from patients who died of South American blastomycosis. These findings were classified and correlated with duration of the disease and treatment. Bile-duct lesions were prominent and a particular pattern was found in which segments of bile ducts were "disrupted" and replaced by inflammatory reaction. A classification of the lesions is proposed: Class o--near normal livers; Class I--predominance of necrosis and suppuration; Class II--predominance of tuberculoid granulomas; Class III--portal fibrosis and non-specific infiltrate. There has been no evidence that treatment could induce bile-duct proliferation, fatty change of liver cells, or cholestasis. On the other hand, less fibrosis was found in treated patients. Pathogenesis of the bile-duct lesions is discussed.

Adolescent↗
PubMed1977

The effects of drugs and denervation on removal and accumulation of adrenaline in the perfused hind-limb of the dog.

Removal of adrenaline by the perfused hind-limb of the dog, as well as its accumulation in the femoral artery and saphenous vein, were studied. Saturation of accumulation occurred at the dose level of 1.5 microng/kg.min-1, whereas removal was not saturated at the dose of 4.5 microng/kg.min-1. Removal of adrenaline was significantly reduced by pretreatment with cortexone, cocaine, phenoxybenzamine and reserpine or by surgical denervation of the limb; enzymatic inhibition by iproniazid or U-0521 had no significant effect on removal. Denervation, reserpine and cortex-one blocked the accumulation of adrenaline, whereas U-0521 was the only drug to increase accumulation of adrenaline. The blood vessels perfused have shown a high capacity of removal of adrenaline from the circulating blood, and thus may play an important role in termination of action of both exogenous and adrenal adrenaline.

Animals↗
PubMedDate not supplied

POEMS syndrome: ultrastructural observations on the sural nerve.

POEMS is an acronym that stands for a multisystem disorder that includes progressive sensorimotor Polyneuropathy, Organomegaly, Endocrinopathy, an M component in blood and/or concentrated urine, and Skin changes. The morphology of the peripheral nerves was mentioned in some of these cases and ranged from normal to those with segmental demyelination and/or degeneration of myelinated axons. We analyzed quantitatively the sural nerves of two cases of POEMS syndrome. Both nerves showed a severe loss of myelinated fibers, with a minor degree of regeneration. Degeneration of unmyelinated axons was observed, but to a lesser degree. There was marked collagen deposition in the endoneurium. The pathogenesis of the changes in the peripheral nerves and other organs in POEMS syndrome is still to be elucidated.

Adult↗
PubMedDate not supplied

Experimental atherogenesis and vascular noradrenaline content in NZW rabbits and activity of a new nicotinic acid derivative (L 44-0).

New Zealand White rabbits fed a low-level cholesterol-enriched diet (0.1%) were used to study and characterize a possible model of experimental atherogenesis. For the determination of the degree of atherosclerosis, more consistent and reproducible morphometric methods were used. Simultaneously the influence of plasma cholesterol levels on vascular noradrenaline content was studied. The effect of a new lipid-regulating drug (0.1% L 44-0, the N-oxide of a nicotinic acid derivative) on analyzed parameters was studied as well. This study suggests that the low-level cholesterol-enriched diet is atherogenic, with macroscopically detectable lesions of atherosclerosis becoming apparent by week 12 of the study. The same diet increases the vascular noradrenaline content in the renal artery and in the femoral artery and vein; however, it does not influence that content in the carotid and mesenteric arteries. L 44-0 counteracts most of the observed effects.

Animals↗