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Biomedical subjects

F Ortega

Publications and source records attributed to F Ortega.

At least 91 records · Page 5Linked to original sources
PubMed1994

Homocysteate-like immunoreactivity in multiform glioblastoma of human brain.

Anti-homocysteate antibodies with postembedding immunohistochemistry for light microscopy were used to localize homocysteate-like immunoreactivity in human multiform glioblastoma. The most remarkable stained elements (6.8% of the total tumoral tissue) corresponded to distinct astrocytic cell bodies, intermingled fibrous processes and puncta of diverse size, some of them closely apposed to capillaries. In not affected peritumoral tissue, on the other hand, numerous labelled dots resembling portions of glial processes were observed in the neuropil and around blood vessels (2.7% of the total peritumoral tissue). However, glial and neuronal cell bodies could not be detected. These observations extend to a human brain tumor of glial nature the knowledge on the preferential localization of homocysteate in glia.

Brain↗
PubMed1994

Glutamate-immunoreactive climbing fibres in the cerebellar cortex of the rat.

The climbing fibre system, one of the two main excitatory inputs to the cerebellar cortex, is anatomically and physiologically well characterized, while the nature of its neurotransmitter is still a matter of debate. We wished to determine whether glutamate-immunoreactive profiles with the morphological characteristics of climbing fibres could be found in the rat cerebellar cortex. For this purpose, a monoclonal 'anti-glutamate' antibody has been used in combination with a sensitive postembedding immunoperoxidase method on semi-thin sections or in combination with a postembedding immunogold method on ultrathin sections. At the light microscopic level, climbing fibres appeared as strongly stained fibrous profiles, chains of interconnected varicosities or heavily labelled dots of various sizes, often in close apposition to principal Purkinje cell dendrites. At the electron microscopic level, certain labelled varicosities or more elongated profiles resembling climbing fibre terminals were in synaptic contact with dendritic spines of Purkinje cells. Quantitative analysis of gold particle densities showed that such elements were about three to four times more heavily labelled than their postsynaptic partners. The results obtained in this study demonstrate that at least a subset of climbing fibres and their terminals contain relatively high levels of glutamate-like immunoreactivity and provide additional evidence for a role of glutamate as transmitter in these cerebellar afferents.

Animals↗
PubMed1994

Neuronal and glial localization of homocysteate-like immunoreactivity in the rat retina.

To study the distribution of L-homocysteate in the rat retina, specific polyclonal and monoclonal anti-homocysteate antibodies have been used in combination with a highly sensitive postembedding method for light microscopic immunocytochemistry. In central and peripheral retina, the most strongly immunoreactive cell bodies lay in the inner nuclear layer. They represented about 17% of the total neuronal cell population of the layer and were identified as bipolar cells (19-20% of cells in the outer half of the inner nuclear layer) and amacrine cells (15% of cells in the inner half of the inner nuclear layer). A third cell type showing heavy homocysteate-like immunoreactivity was identified as Müller glial cells. Characteristically, their descending processes formed three immunoreactive bands in the inner plexiform layer. Furthermore, the outer and inner limiting membranes as well as glia around and between ganglion cell axons and in the vicinity of blood vessels were labelled intensely. Photoreceptors and their terminals, and ganglion cells, were not immunostained. These findings indicate the presence of homocysteate in some bipolar and amacrine cells of the inner nuclear layer and support a role for this sulphur-containing excitatory amino acid as a neurotransmitter candidate in the retina.

Animals↗
PubMed1994

Venous reflux in patients with previous deep venous thrombosis: correlation with ulceration and other symptoms.

PURPOSE: Deep vein thrombosis (DVT) in many cases leads to chronic symptoms in the damaged leg, even though the affected veins have recanalized. The major hemodynamic defect in such recanalized veins is reflux. The incidence and extent of reflux has been studied in patients with proven DVT and correlated with concurrent symptoms. METHODS: Two hundred seventeen limbs in 183 patients were examined by duplex scanning from January 1989 to October 1992. All limbs had previous DVT diagnosed by venography. Sites and extent (proximal, distal, or both) of reflux were identified by meticulous duplex scanning of the whole venous system and correlated with presenting symptoms. RESULTS: The patients were classified into nine groups on the basis of the classification of the system involved (superficial, deep, or superficial and deep) and whether the reflux was found proximal or distal to the knee or both. Eight-one limbs belong to chronic venous insufficiency class 1, 92 belong to class 2, and 38 belong to class 3. Reflux was confined to the deep venous system in 84 limbs (38.7%), to the superficial system in 31 (14.3%) limbs, and to both systems in 102 (47%) limbs. It was confined to proximal veins only in 48 (22.1%) limbs, distal only in 56 (25.8%) limbs and throughout the limb in 113 (52.1%) limbs. The incidence of swelling was increased by distal or a combination of proximal and distal reflux regardless of which system was involved. In limbs with superficial venous insufficiency (SVI) or deep venous insufficiency (DVI) only, the incidence of skin changes was not affected by the extent of reflux. However, in limbs with combined SVI and DVI, it was increased in the presence of reflux throughout the limb. Absence of distal reflux was associated with a low incidence of skin changes even in the presence of DVI. Ulceration increased with an increased extent of reflux in the presence of SVI. Absence of superficial reflux was associated with a low incidence, even in the presence of DVI. CONCLUSIONS: The data suggest that as far as the skin changes and ulceration are concerned, distal reflux and reflux in the superficial veins are more harmful than reflux confined to the deep veins, even when such reflux extends throughout the deep venous system.

Adolescent↗
PubMed1994

Role of cardiopulmonary exercise testing and the criteria used to determine disability in patients with severe chronic obstructive pulmonary disease.

The aim of this study was to evaluate the precision and variability with which resting pulmonary function tests (resting PFTs) can be used to predict the capacity in exercise, and the usefulness of the different measurements of pulmonary function in the evaluation of impairment/disability in patients with chronic obstructive pulmonary disease (COPD). We studied 78 patients with stabilized COPD (FEV1 45.1 +/- 17.1%). Of these, 39 suffered severe impairment according to the resting PFTs. Both the group with severe impairment (maximal oxygen consumption [VO2,max]: 16.22 +/- 5 ml/kg/min; maximal minute ventilation [VEmax]: 31.87 +/- 7.1 L/min; maximal heart rate [HRmax]: 133.8 +/- 10.9 beats/min) and the group with nonsevere impairment according to the resting PFTs (VO2max: 22.55 +/- 7.9 ml/kg/min; VEmax: 42.11 +/- 10.9 L/min; HRmax: 138 +/- 13.7 beats/min) showed ventilatory limitation during exercise. FEV1 was the most prevalent criterion for the determination of severe impairment (FEV1 < 40%), and was the variable best correlated to VO2max (r = 0.52 with VO2max as absolute value and r = 0.54 with VO2max expressed as a percentage of the reference value), but the resting PFTs were not predictive of exercise performance including patients with severe COPD. Evaluation of working capacity (based on VO2max) revealed a significant number of inaccurate predictions among the results of the resting PFTs. Sensitivity and specificity analysis were used to compare the different criteria used to evaluate the severity of disability. They reveal that the classification will be different according to the criteria used.(ABSTRACT TRUNCATED AT 250 WORDS)

Disability Evaluation↗
PubMed1994

Thumb rule of visual angle: a new confirmation.

The classical thumb rule of visual angle was reexamined. Hence, the visual angle was measured as a function of a thumb's width and the distance between eye and thumb. The measurement of a thumb's width when held at arm's length was taken on 67 second-year students of psychology. The visual angle was about 2 degrees as R. P. O'Shea confirmed in 1991. Also, we confirmed a linear relationship between the size of a thumb's width at arm's length and the visual angle.

Adult↗
PubMed1993

Long term follow up of haemophilic arthropathy treated by Au-198 radiation synovectomy.

Intra-articular injection of Au-198 (gold synoviorthesis) has been used in the treatment of repeated haemarthroses of the elbows, knees, or ankles in 64 haemophiliacs. These patients had continued to have joint haemorrhages despite appropriate, episodic, substitutive therapy over a period of more than six months. Follow-up for an average period of 14 years in one knee in 38 male haemophiliacs showed 8 good, 23 fair, and 7 poor results with regard to their joint scores. It is concluded that Au-198 is an effective agent for radiation synovectomy, particularly in the early stages of the disease with minimal radiographic changes. It appears to reduce the incidence of haemarthrosis and to slow the rate of evolution of radiographic changes.

Adolescent↗
PubMed1993

Amperometric biosensor for the determination of phenolic compounds using a tyrosinase graphite electrode in a flow injection system.

Selective and sensitive devices for the monitoring of phenol and phenolic compounds are required in clinical and environmental analysis. This paper describes a biosensor for the analysis of phenolic compounds in a flow injection system. The enzyme electrode is based on the use of immobilized tyrosinase and the amperometric detection of the enzymatic product at -50 mV vs. SCE. The enzyme is covalently immobilized on the surface of a carbodiimide-activated graphite electrode. The biosensor responds to a variety of phenolic substrates with different conversion efficiencies. The detection limit for phenol is 0.003 microM (S/N = 3), a quantification limit of 0.01 microM (rsd 3.7%), and an extended dynamic range up to 5 microM is achieved with a sample frequency of 110 samples per hour.

Biosensing Techniques↗
PubMed1993

Retinal afferents on Golgi-identified vertical neurons in the superior colliculus of the rabbit. A Golgi-EM, degenerative and autoradiographic study.

The characteristics and distribution pattern of retinal afferent terminals making synaptic contacts on narrow field vertical neurons in the stratum griseum superficiale of the rabbit superior colliculus were studied using the Golgi-gold substitution technique in combination with either autoradiographic or degenerative methods. At the level of light microscopy, identified gold-toned vertical neurons showed similar features to those previously described by others. Although their axons were frequently seen rising from the basal dendritic tuft, they could also emerge from an apical dendrite, but rarely from the cell body. The electron microscopic study revealed that these neurons received radiolabelled or degenerated profiles with typical features of retinal terminals, while more proximal parts seemed to receive fewer terminals but of larger size. Axo-somatic synaptic junctions were very rare and, interestingly, retinal terminals were not seen forming synapses on the basal dendritic arborization. The present results indicate that the narrow field vertical cells are targets for retinotectal projection.

Animals↗
PubMed1992

[Prognostic effect of beta 2-microglobulin in multiple myeloma].

BACKGROUND: The aim of the present study was to compare the prognostic influence of beta 2-microglobulin (B2M) corrected according to renal function versus the uncorrected form and relate these values with other characteristics of the disease in a series of patients with multiple myeloma (MM). METHODS: The serum levels of B2M were determined by the radioimmunoassay method (RIA) in 107 patients with newly diagnosed MM and the prognostic influence of B2M was statistically evaluated with univariant and multivariant analysis. RESULTS: The mean value of B2M obtained in patients with MM was 7.8 +/- 8.0 micrograms/ml, with a median of 5 micrograms/ml. Ninety percent of the patients studied presented serum values of B2M higher than the normal limit. The value of B2M corresponding to the median of the series (5 micrograms/ml) separated two groups of patients with different survival (48 vs 19 months) (p = 0.0001). Similarly, the most discriminative value of corrected B2M in agreement with creatinine (2.5 micrograms/ml) permitted the differentiation of two groups of patients although the differences in survival were less significant (36 vs 26 months, p = 0.03) demonstrating its lesser influence as a prognostic factor with respect to the uncorrected B2M. In contrast, a significant association was observed between high values of B2M and Bence Jones myeloma, clinical stage III, anemia, renal failure and intense involvement of the general state. Multivariant analysis demonstrated that B2M plays a greater prognostic role when used as a discrete rather than a continuous variable and that together with the degree of involvement of the general state, serum albumin and the proportion of plasma cells in the bone marrow, they make up the best set of variables for the prediction of prognosis in patients with MM. CONCLUSIONS: Beta 2-microglobulin is one of the most important independent prognostic factors in multiple myeloma with its prognostic value being greatest when used uncorrected according to the values of creatinine.

Bence Jones Protein↗
PubMed1992

Increased expression of natural-killer-associated and activation antigens in multiple myeloma.

The expression of both natural-killer (NK)-associated and activation antigens was studied by flow cytometry in the peripheral blood of 47 untreated multiple myeloma (MM) patients. A significant increase in both absolute and relative numbers of CD57 positive cells as well as in the proportion of CD16 and CD11b cells was observed in patients with MM, specially in those in early stages of the disease (clinical stages I and II), suggesting a possible surveillance mechanism in response to an emerging malignant clone. Additional double stainings showed that strong CD16+ NK cells coexpress the CD56, CD11b, and CD2 antigens, while they lacked CD3, CD5, and WT31 antigens. Moreover, the previously reported increase in CD8 cells present in MM would be mainly due to a subset of CD8 cells that coexpress the CD57 Ags. The expression of activation antigens, especially CD38, was increased in peripheral blood lymphocytes of MM patients, the differences reaching statistical significance both in absolute and relative numbers in those cases with high numbers of CD16 NK cells and thus suggesting that these cells are functionally activated. These results reveal the existence of an increase in NK and activated cells in the peripheral blood of myeloma patients that may reflect a host's immunological mechanism in an attempt to modulate tumor cell growth.

ADP-ribosyl Cyclase↗
PubMed1992

Treatment of melphalan-resistant multiple myeloma with vincristine, BCNU, doxorubicin, and high-dose dexamethasone (VBAD).

A total of 65 patients (35 male/30 female) with multiple myeloma primarily (33) or secondarily (32) resistant to melphalan and prednisone were treated with vincristine, carmustine (BCNU), doxorubicin, and high-dose dexamethasone (VBAD) at 4-week intervals. Among 60 evaluable patients the overall response was 36.6% (21.6% objective response plus 15% improvements). The response rate was significantly higher in primarily resistant patients than in those becoming resistant after a prior response (48.4 vs. 24.1%, P < 0.05). The median duration of response was 17.5 months. When survival of responders and non-responders were compared by the conventional method, a highly significant difference was observed (P < 0.001). However, using the Mantel and Byar procedure and the landmark method, only a trend for longer survival in the responders was registered. These results indicate that although VBAD is effective in at least one third of patients with advanced multiple myeloma resistant to melphalan, its impact on survival is limited.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Lymphoid subsets and prognostic factors in multiple myeloma. Cooperative Group for the Study of Monoclonal Gammopathies.

In a uniform series of 170 untreated myeloma patients (MM) we investigated the distribution of T cell subsets in peripheral blood (PB) and their relationship with the most relevant disease characteristics, including survival. CD4 cells were significantly decreased both in percentage and absolute numbers (P less than 0.0001). On the other hand, the CD8 cells only showed a slight increase in relative numbers. Upon correlating the abnormalities in the distribution of T cells with other clinical and biological disease characteristics the most remarkable correlation was with survival. A low number of CD4 cells (less than 700 x 10(6)/l) was associated with both an advanced clinical stage and a shorter survival (20 v. 43 months, P = 0.01). Moreover, a significant correlation also exists between the decrease in CD4 cells and both high beta 2-microglobulin (beta 2M) levels and anaemia. On the other hand, no relationship was found with the type of M-component nor with the plasma cell phenotype. Finally multivariate analysis showed that the number of CD4 cells add independent prognostic information to other well-established tests for the assessment of disease outcome in patients with multiple myeloma.

Age Factors↗
PubMed1992

AIDS and hemophilia: experience in the La Paz Hemophilia Center.

435 hemophiliacs are usually being attended in the La Paz hemophilia Center (Madrid, Spain). 257 (59%) of these patients have been infected by the human immunodeficiency virus (HIV-1) because of human plasma derivate substitution therapy. The infection has been more frequent among the severely affected patients and among the most treated patients. 82% of the infected patients are between 14 and 40 years old. By December 1991, 95 (37%) of 257 seropositive patients have developed full-blown AIDS. The most frequent opportunistic infection they had suffered was esophageal candidiasis. Looking for an evolution marker, we can point that the patients older than 35 years with CD4 levels below 200/mm3 had the worst prognosis. There was no difference in the evolution among the patients aged below 17 and those aged between 17 and 35 years. The amount of concentrate used between 1980 and 1984 did not hold any relation to the evolution. 49 patients (51%) of the 95 suffering from AIDS had died by December 1991. The evolution to the death was unrelated to the patient age, CD4 lymphocyte levels, and amount of substitution therapy. In our opinion, the most valuable marker could be the kind of opportunistic infection or tumor the patient suffers from. Finally, Retrovir has demonstrated to be useful in increasing the survival rate of the patients, but after 36 months of treatment, only 33% of those AIDS patients who began taking it remained alive. Retrovir was also used in asymptomatic patients, and during an average period of time of 15 months, a lesser bone marrow toxicity and a stabilization in CD4 lymphocyte levels could be observed, but this was unable to modify the disease progression in those patients who presented circulating p24 antigen.

AIDS-Related Opportunistic Infections↗
PubMed1992

[Utility of the examination of plasma-cell morphology in the study of multiple myeloma].

PURPOSE: To assess the classification of Greipp et al in a group of multiple myeloma (MM) patients, in an attempt to correlate the morphological patterns with the clinico-biological features of the disease. MATERIAL AND METHODS: Bone marrow aspirates from 135 patients with multiple myeloma were examined by two different observers. RESULTS: Full accordance existed in 122 cases (90%). The four morphological MM subgroup distribution was: mature, 38%; intermediate, 30%; immature, 18%, and plasmoblastic, 14%. The analysis of the M component types with regard to morphology showed increased IgA cases within the intermediate (40%) and immature (48%) MM (p = 0.01), and Bence-Jones cases within the plasmoblastic MM (32%). On the contrary, no differences were found with regard to the clinical stage, although none of the plasmoblastic MM was in stage I. The incidence of renal insufficiency and of high bone-marrow infiltration progressively increased from mature to plasmoblastic MM, the difference between the extreme morphological groups being significant. The incidence of hypercalcaemia and lower paraprotein rates was higher in plasmoblastic myeloma, with significant difference with respect to mature myeloma (p = 0.05). The median survival was longer in intermediate (27.8 months) and mature (22.5 months) myelomas than in plasmoblastic (17.9 months) and immature (13.6 months) myelomas. After grouping the mature forms (intermediate plus mature) and the immature ones (plasmoblastic plus immature) the survival differences approached statistical significance (p = 0.07). CONCLUSIONS: This study suggests that the morphological examination of plasma cells should be included in the prognostic criteria of multiple myeloma.

Aged↗