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Biomedical subjects

F González

Publications and source records attributed to F González.

At least 73 records · Page 4Linked to original sources
PubMed2000

A time-dependent expression for thixotropic areas. Application to aerosil 200 hydrogels.

Experimental determination of the areas enclosed under the up curve, sigma = sigma(;gamma), corresponding to time zero, and the down curve, which would be obtained following complete rheodestruction of the system structure, is not an easy matter. In the present study a semi-empirical procedure for calculating the hypothetical values of these parameters is proposed. With these parameters it is possible to obtain a time-dependent expression for the thixotropic areas, S(T). This procedure has been applied to the study of the thixotropic behavior of Aerosil 200 hydrogels at different concentrations. The comparative analysis of these systems has been realized by studying the relative thixotropic areas and relative thixotropic rates that are obtained from S(T).

Area Under Curve↗
PubMed2000

Central serous chorioretinopathy following pigment epithelium detachment: fluorescein and indocyanine green angiography follow-up.

PURPOSE: To evaluate the evolution from idiopathic serous pigment epithelium detachment (PED) to central serous chorioretinopathy (CSC). METHODS: Fluorescein angiography (FA) and indocyanine green angiography (ICGA) were performed using the digital imaging system Topcon IMAGEnet H 1024. RESULTS: A leakage point which later became the typical smokestack image of a CSC was found in the upper margin of the persistent PED. Dilation of the choroidal vessels under the detached neuroepithelium was also seen. CONCLUSIONS: Clinical and angiographic evidence about the relation between the two entities can help us to understand CSC as a potential evolution of PED and to continue searching for the common injury of the pigment epithelium which probably is the primary event.

Choroid↗
PubMed2000

Radiotoxicity of h-R3 monoclonal antibody labeled with 188Re administered intracerebrally in rats.

Brain tumors are often incurable despite current aggressive treatment modalities. Regional intracerebral administration of labeled monoclonal antibodies (Mabs) can maximize the radioisotope and Mab concentration to tumor sites while reducing systemic toxicity. h-R3 is a humanized antiepidermal growth factor receptor Mab that successfully targets the epidermal growth factor receptor, which is overexpressed in glioblastomas. We studied the acute local and systemic toxicity effects of intraventricular 188Re-h-R3 in rats. Forty rats were distributed into four groups with five animals of each sex in each group. A single 5 -microl dose (2.5 microl into the left and 2.5 microl into the right lateral ventricles) of neutral solution containing 50 microg of h- R3 labeled with 49.5 +/- 1.7,284 +/- 13.7 or 579 +/- 23.7 muCi of 188Re were stereotactically administered to each animal. Control animals received vehicle alone. Each animal was observed twice daily for detection of toxicity signs. Body weights were recorded on days 0, 7 and 14. Blood samples for analysis of hematological and clinical chemistry parameters were taken on days 0 and 14. Necropsy and histopathological studies were carried out after completion of the study. All animals, but one, remained clinically stable. Toxicities included local radionecrosis, discrete increase in ALAT and creatinine blood values at higher dose level. We concluded that a single intraventricular administration of relatively large doses of 188Re-h-R3 is tolerable and causes minimal local and systemic toxicity effects in rats. Nevertheless, further studies are necessary to discard learning and behavioral problems.

Adenocarcinoma↗
PubMed2000

[Tubal involvement in nasopharyngeal carcinoma].

Nasopharyngeal carcinomas are frequently diagnosed in advanced stages in patients who present with secretory otitis or neck mass. However, survival after treatment is directly related to early diagnosis. The present study analyzed Eustachian tube involvement in nasopharyngeal carcinoma as a pathogenic mechanism in secretory otitis. The presence of otologic symptoms was correlated with the morphological description of the tumor and clinical manifestations in 198 patients with nasopharyngeal carcicoma.

Carcinoma↗
PubMed2000

True hermaphroditism in a horned goat with 60XX/60XY chimerism.

Anatomical, behavioral, histological, endocrinological, and cytogenetic characteristics were determined in a horned intersex goat. Histology of the gonads confirmed that the goat was a true hermaphrodite. Cytogenetic analysis showed that it was a chimera (60XX/60XY). Use of laparoscopy allowed determination of characteristics of the internal gonads.

Animals↗
PubMed2000

[Increased activity of metalloproteinases and their inhibitors in cerebrospinal fluid of patients with tropical spastic paraparesis].

BACKGROUND: Proteolytic modifications of neuronal surfaces and the surrounding extracellular matrix are very important in neuronal development and regeneration. Increased activity of matrix metalloproteinases (MMPs) and their tissue inhibitors, due to secretion by macrophages and lymphocytes, occur in inflammatory processes that disrupt the blood brain barrier. However, neurons and microglia can also secrete these enzymes. AIM: To identify the type of MMP present in the cerebrospinal fluid (CSF) and changes in the expression of tissue inhibitors of metalloproteinases (TIMPs) in patients with HTLV-1 associated tropical spastic paraparesis. PATIENTS AND METHODS: CSF samples from 12 patients with HTLV-1 associated tropical spastic paraparesis and 12 healthy controls were obtained by an atraumatic lumbar puncture. The presence of MMPs was measured by zymography and the relative amounts of TIMPs were measured by immunowestern blot. RESULTS: In the CSF of both controls and patients, a similar gelatinolytic band corresponding to proMMP-2 (latent form) was observed. In 83.3% of patients with HTLV 1 associated tropical spastic paraparesis, the MMP-9 was also present. TIMP-1, TIMP-2 and TIMP-3 were elevated 2.24 +/- 0.72, 3.85 +/- 1.38 and 5.89 +/- 3.4 fold, respectively, in the CSF of patients as compared to controls. CONCLUSIONS: Patients with HTLV-1 associated tropical spastic paraparesis have elevated activity of MMP-9 and levels of TIMPs in the CSF, when compared to healthy controls.

Adult↗
PubMed2000

Atlanto axial instability due to neurofibromatosis: case report.

Neurofibromatosis is an autosomal dominant genetic disease, characterized by café au lait spots, neurofibromas and several bony anomalies. Deformities of the spine are the most frequent alterations. Involvement of the cervical spine has been studied less frequently. The case of a 16-year-old male patient affected by neurofibromatosis, with cervical pain without neurological symptoms is presented. X-rays, CT-scan and MRI demonstrated the presence of cervical kyphosis, occipitoaxial instability and atlantoaxial instability with subluxation. Posterior occipito-C2 fusion was performed with prior placement of a halo-vest. The outcome at four years was good with solid occipito axial fusion, moderate loss of cervical spine flexion and moderate-to-severe limitation of cervical spine rotation. The incidence and variety of alterations of the cervical spine in patients affected with neurofibromatosis is discussed, as well as the results obtained by the treatment.

Adolescent↗
PubMed2000

[Cefepime in the treatment of osteomyelitis caused by Gram negative bacilli].

We conducted a prospective, randomized, open-label trial to evaluate the efficacy and tolerability of cefepime in the treatment of osteomyelitis caused by Gram-negative bacilli. Hospitalized patients with diagnosis of osteomyelitis due to Gram-negative bacilli susceptible to cefepime were elegible for enrollment. Cefepime was administered intravenously or intramuscularly (2 g every 8 or 12 hours). Microorganisms were considered susceptible to cefepime when the MIC was <8 mg/l. Forty-five patients with bone infections were enrolled, forty-three with osteomyelitis (22 chronic and 21 acute) and two with arthritis. In the per protocol analysis 42 patients were evaluated: 30 (71.4%) were cured. In the intent to treat analysis 45 patients were evaluated: 33 (73.3%) were cured. Our trial suggests that cefepime is as effective as other modern parenteral beta-lactam antibiotics in the treatment of osteomyelitis due to Gram-negative bacilli.

Acute Disease↗
PubMed1999

The immune response and PBMC subsets in canine visceral leishmaniasis before, and after, chemotherapy.

Peripheral blood mononuclear cell subsets, in vitro lymphoproliferative response to leishmanial antigen, and Leishmania-specific serum antibody levels were examined in 11 dogs, naturally infected with L. infantum, and 9 healthy control dogs. A decrease in the percentage of CD4+ T-cells and an increase in the proportion of gammadelta T-cells and sIgG+ B-cells were observed during canine visceral leishmaniasis (CVL). These changes may be responsible for the marked humoral response and the absence of in vitro lymphoproliferation to mitogen and specific parasite antigens. This possibility was supported by the analysis of these subsets after treatment with amphotericin B. One month after therapy, a significant increase in the percentage of CD4+ T-cells and a decrease of gammadelta T-cells and sIgG+ B-cells were observed. At the same time, the lymphocyte blastogenesis assay with leishmanial antigen was positive and the levels of specific antibodies to Leishmania were significantly lower than before the treatment. Five months after therapy, lymphocyte proliferative response to LSA disappeared, antibody and lymphocyte subsets levels returned to those observed during CVL. Therapeutic failure in CVL is associated with the inability of antileishmanial drugs to completely revert the profound immunodepression induced by the infection and prevent relapse.

Amphotericin B↗
PubMed1999

Involvement of methionine residues in the fast inactivation mechanism of the sodium current from toad skeletal muscle fibers.

The role of methionine residues on the fast inactivation of the sodium channel from toad skeletal muscle fibers was studied with the mild oxidant chloramine-T (CT). Isolated segments of fibers were voltage clamped in a triple Vaseline gap chamber. Sodium current was isolated by replacing potassium ions by tetramethylammonium ions in the external and internal solutions. Externally applied chloramine-CT was found to render noninactivating a large fraction of sodium channels and to slow down the fast inactivation mechanism of the remainder fraction of inactivatable channels. The action of CT appeared to proceed first by slowing and then removing the fast inactivation mechanism. The voltage dependence of the steady-state inactivation of the inactivatable CT-treated currents was shifted +10 mV. CT also had a blocking effect on the sodium current, but was without effect on the activation mechanism. The effects of CT were time and concentration dependent and irreversible. The use of high CT concentrations and/or long exposure times was found to be deleterious to the fiber. This side effect precluded the complete removal of fast inactivation. The effects of CT on the fast inactivation of the sodium current can be explained assuming that at least two methionine residues are critically involved in the mechanism underlying this process.

Animals↗
PubMed1999

Early pregnancy diagnosis in goats by determination of pregnancy-associated glycoprotein concentrations in plasma samples.

Different RIA systems available for measuring the concentrations of pregnancy-associated glycoproteins (PAGs) in dairy goats were compared in order to evaluate their accuracy in early pregnancy diagnosis. Plasma concentrations of PAGs were determined by 3 heterologous RIA systems with a bovine PAG standard and tracer in combination with antisera anti-ovine PAG (RIA 1), anti-caprine PAG55 + 62 (RIA 2), anti-caprine PAG55 + 59 (RIA 3), and by 2 homologous RIA systems that employed caprine PAG55 + 62 and caprine PAG55 + 59 and their specific antisera (RIAs 4 and 5, respectively). In all of the RIAs, the mean concentrations of PAGs were significantly higher (P < 0.01) in pregnant than in nonpregnant goats from Day 21 onwards after breeding. On Day 21, the accuracy rates of early pregnancy diagnoses were 56% (RIA 1), 96% (RIA 2), 99% (RIA 3), 95% (RIA 4) and 90% (RIA 5), whereas on Day 28 these rates were > 99% for RIAs 2, 3, 4 and 5. The RIAs for PAGs depend on proteins from the placenta being present in maternal plasma and require only a single sample of blood, to distinguish pregnant goats from those that fail to return to estrus for other reasons. The homologous and semi-heterologous assays are highly accurate as early as Day 21 of pregnancy.

Animals↗
PubMed1999

Pemphigus vulgaris: benefits of tetracycline as adjuvant therapy in a series of thirteen patients.

BACKGROUND: Tetracycline is an antibiotic which has been proven beneficial as an immunomodulating drug in the treatment of autoimmune bullous diseases. METHODS: Thirteen hospitalized patients with pempigus vulgaris received tetracycline 2 g/day for 1 month, then 1 g/day for the following 4 weeks. Prednisone 0.5-1 mg/kg/day was then gradually reduced. The control group consisted of seven patients with pemphigus who had received prednisone and azathioprine. RESULTS: A total of 13 patients in the study group achieved cessation of new blister formation within 5.4 days, compared to 23.71 days (p < 0.0001). The average initial dose of prednisone was 76.53 mg/day for the study group and 118.57 mg/day in the control group (p < 0.014). The average number of days before reduction of the prednisone dosage could begin was 16.53 days for the study group compared to 31.28 days in the control (p < 0.049). Total hospitalization time was also significantly lower: 34.07 days (p < 0.001). The clinical response was not linked to the location of lesions nor to severity of disease. CONCLUSIONS: Tetracycline was shown to be effective as an adjuvant therapy for pemphigus with low toxicity and safety.

Adult↗