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Biomedical subjects

J M Delgado

Publications and source records attributed to J M Delgado.

At least 19 recordsLinked to original sources
PubMed2004

Endobronchial brachytherapy in the treatment of malignant lung tumours.

A prospective study was made to assess the short-term clinical and endoscopic response to high-dose-rate endobronchial brachytherapy (HDREB) in patients with malignant endobronchial tumours. From July 1995 to May 2000, 288 HDREB sessions were carried out on 81 patients. The mean patient age was 61.57 yrs (range 34-82); males were predominant (87.65%). Tumours were primary in 76 patients (93.82%) and metastatic in five patients (6.18%). The inclusion criteria were malignant endobronchial tumour and either palliative treatment for incurable disease or intent-to-cure treatment for residual malignancy on the bronchial resection surface after surgery or an inoperable tumour. The exclusion criteria were as follows: impediments to catheter placement, expected survival <2 months, Karnofsky index <60, or absence of informed consent. The clinical response of a symptom was categorised as complete (disappearance of the symptom), partial (less than complete) or absent. The endoscopic response was considered to be complete if lesions disappeared and biopsy findings remained negative 1 month after the last radiation session; partial if lesions improved to some extent, but the biopsy findings were positive; and absent if there was no change in relation to baseline. The technique consisted of delivering high-dose irradiation from an Ir192 source to a target volume using one or two endobronchial catheters inserted under optical or video bronchoscopic guidance. Four sessions were scheduled at weekly intervals and 500 cGy was applied per session over a length of 1-9 cm, measured 0.5-1 cm from the centre of the source. In total, 85% of the symptoms analysed (haemoptysis, cough, dyspnoea, expectoration, and stridor) disappeared with HDREB, which was categorised as a complete response. The endoscopic response was complete in 56.79% of patients, partial or less than complete in 40.74% and absent in 2.46%. One major complication occurred (bronchial fistula 1.2%), but no lethal haemoptysis. Minor complications (pneumonitis, bronchospasm and bronchial stenosis) each occurred in one patient (1.2%). High-dose-rate endobronchial brachytherapy is a good palliative treatment for endoluminal lung neoplasms, effectively alleviating symptoms and endoscopic evidence in many cases with an acceptable rate of complications. High-dose-rate endobronchial brachytherapy can be carried out as an intent-to-cure procedure in highly selected cases.

Brachytherapy↗
PubMed2000

Effects of arsenite on central monoamines and plasmatic levels of adrenocorticotropic hormone (ACTH) in mice.

We studied the effects of chronic arsenic exposure on brain monoamines and plasma levels of adrenocorticotropic hormone (ACTH) of mice. After weaning, mice received arsenic (0, 20, 40, 60 or 100 ppm) in drinking water over a period of 9 weeks. Monoamine content was quantified in different brain regions, arsenic was quantified in brain tissue and ACTH levels in plasma. Brain arsenic concentrations up to 200 ng/g showed a significant correlation with exposure levels and produced slight modifications in regional monoamine levels. ACTH plasma levels were significantly associated with norepinephrine (NE) concentrations in the medulla and pons, but not with hypothalamic NE levels. ACTH levels were significantly higher in the group exposed to 20 ppm. Dopamine showed significant dose-related decreases in the hypothalamus. These results show that chronic sodium arsenite exposure produces changes in central monoamines, which are not associated on a dose-dependent basis with major alterations in plasma ACTH.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2000

Neuronal imprinting of human values.

In the 21st century, psychophysiology will face the challenge of establishing ethical principles and practical means for the genetic and social influencing of the development of human beings. Neuronal imprinting of beliefs and morality within infantile minds will be necessary for the peaceful coexistence of races and cultures. This process requires study and consideration, among others, of the following psychophysiological facts: (1) Genes do not transmit moral values. (2) Material support of physiological activities is necessary for the existence and development of mental functions. (3) Imprinting of human values is based on material changes within neuronal structures. (4) Early neuronal imprinting is performed without personal awareness or consent of the individual and depends on sensory inputs, mainly from the social structure of the group. (5) Biological structures lack values. Personal and social antagonisms do not depend on genes, but on cultural indoctrination. (6) Pleasure and punishment (positive and negative reinforcement) are the two main elements, which regulate animal and human behavior. (7) Values must be chosen by adults, who decide the questions 'why'? 'when'? 'which ones'?, 'who should teach'?, 'what?' and 'how'? (8) Many biological imperatives are shared by all animals and by all people. Human beings may be considered the 'crickets of the Universe', unable to understand the mysteries of nature because of our insufficient neuronal capacity. (9) Our emotional life is mainly related to the structure of the limbic system controlled by the neocortex. (10) New theories based on the integration of physics, chemistry, biology and other specific areas of knowledge, as proposed by the General Theory of Systems, will avoid 'opposites', favoring the acceptance of complementary aspects of reality. (11) Early education will promote preferential learning which depends on both genetic endowment and neuronal development influenced by experience. It is the responsibility of psychophysiology to establish the guidelines for better education, clarifying the material and psychological aspects of the mind.

Humans↗
PubMed2000

Exact analytical solution of the convolution integral equation for a general profile fitting function and Gaussian detector kernel.

One of the most important aspects in the metrology of radiation fields is the problem of the measurement of dose profiles in regions where the dose gradient is large. In such zones, the 'detector size effect' may produce experimental measurements that do not correspond to reality. Mathematically it can be proved, under some general assumptions of spatial linearity, that the disturbance induced in the measurement by the effect of the finite size of the detector is equal to the convolution of the real profile with a representative kernel of the detector. In this work the exact relation between the measured profile and the real profile is shown, through the analytical resolution of the integral equation for a general type of profile fitting function using Gaussian convolution kernels.

Densitometry↗
PubMed1998

Cloning and sequence analysis of the gene encoding invertase (INV1) from the yeast Candida utilis.

The gene INV1 encoding invertase from the yeast Candida utilis has been cloned using a homologous PCR hybridization probe, amplified with two sets of degenerate primers designed considering sequence comparisons between yeast invertases. The cloned gene was sequenced and found to encode a polypeptide of 533 amino acids that contain a 26 amino-acid signal peptide and 12 potential N-glycosylation sites. The nucleotide sequences of the 5' and 3' non-coding regions were found to contain motifs probably involved in initiation, regulation and termination of gene transcription. The amino-acid sequence shows significant identity with other yeast, bacterial and plant beta-fructofuranosidases. The INV1 gene from C. utilis was able to complement functionally the suc2 mutation of S. cerevisiae.

Amino Acid Sequence↗
PubMed1998

Development of an integrative DNA transformation system for the yeast Candida utilis.

We report here the development of an auxotrophic transformation system for the food yeast Candida utilis. To facilitate molecular studies in Candida utilis, we isolated auxotrophic strains for uracil biosynthesis by the combination of NTG-mutagenesis and 5-fluorotic acid (FOA) selection. The ura-mutation could be functionally complemented by the homologous URA3 gene. We used both, LiAc and electroporation methods to direct insertions at the ura3 locus through homologous recombination.

Blotting, Southern↗
PubMed1998

Experimental determination of the convolution kernel for the study of the spatial response of a detector.

One of the most important parameters in the characterization of a detector is its spatial convolution kernel. This kernel contains all of the information about the influence that the detector size has on the measured beam profile. In this paper we present an experimental method for the determination of the spatial convolution kernel for commonly used detectors that are employed in the x-ray profile measurement: film + densitometer, diode, and ionization minichamber. Our work is based on first assuming a step function pattern on a photographic film is known and is a perfect step function. The kernel of the densitometer system was then derived from the deconvolution of the scanned profile to the step function. Next a film was exposed to a penumbra area of an x-ray beam from a linac. The film was scanned using the same densitometer. The "real profile" that emerges from a linear accelerator was derived by the deconvolution of the scanned profile using the now known kernel of the film densitometer. Under the same irradiation condition the x-ray profile was measured with other detectors and with this information we obtained the convolution kernels for these detectors by solving numerically their basic convolution integrals. The results show that the Gaussian convolution kernel is the most consistent with the measurements. The best numerical values for the FWHM of the kernels are 1.1 mm, 2.2 mm, and 5.4 mm for densitometer, diode, and minichamber, respectively.

Biophysical Phenomena↗
PubMed1998

Modelling the kinetics of antigen-antibody reactions at particle enhanced optical immunoassays.

Functionalized latexes coated by antibodies are used in diagnostic tests for the detection of antigens in biological fluids. A simple kinetic model is presented which is related to the optical monitoring of the formation of specific complexes between antigen and antibody amplified by latex beads. The antibodies are chemically coupled onto chloromethylstyrene (CMST) particles. The kinetic model is able to describe the immunoprecipitin curves of immunolatex beads. The number of fitting parameters is relatively reduced (only three), and the meaning of these parameters can be interpreted in terms of the chemical equilibrium constant, the percentage of active IgG on the latex beads, and optical response. The model explains very well the optical response of immunolatex prepared by covalent coupling of antibodies on polymer carriers.

Animals↗
PubMed1997

Purification and characterization of an invertase from Candida utilis: comparison with natural and recombinant yeast invertases.

A periplasmic invertase from the yeast Candida utilis was purified to homogeneity from cells fully derepressed for invertase synthesis. The enzyme was purified by successive Sephacryl S-300, and affinity chromatography and shown to be a dimeric glycoprotein composed of two identical monomer subunits with an apparent molecular mass of 150 kDa. After EndoH treatment, the deglycosylated protein showed an apparent molecular weight of 60 kDa. The apparent K(m) values for sucrose and raffinose were 11 and 150 mM, respectively, similar to those reported in Saccharomyces cerevisiae. The range of optimum temperature was 60-75 degrees C. The optimum pH was 5.5 and the enzyme was stable over pH range 3-6.

Blotting, Southern↗
PubMed1996

Invertase secretion in Hansenula polymorpha under the AOX1 promoter from Pichia pastoris.

A DNA fragment containing a transcription regulating region of the alcohol oxidase (AOX1) gene from the methylotrophic yeast Pichia pastoris was used in the construction of a vector for the expression of heterologous proteins in the methylotrophic yeast Hansenula polymorpha. We used this vector to clone the SUC2 gene from Saccharomyces cerevisiae into H. polymorpha yeast. The culture conditions for invertase production using a fed-batch culture were studied. More than 1.5 x 10(3) U/ml of biologically active invertase (1 g/l) were secreted to the cellular periplasmic space. The fermentative process was scaled up to 50 l. Invertase produced from H. polymorpha was glycosylated, but it contained significantly less carbohydrate than protein produced by S. cerevisiae. Using the Western-blot technique, it was observed that invertase secreted from H. polymorpha and invertase secreted from S. cerevisiae showed common antigenic determinants.

Alcohol Oxidoreductases↗
PubMed1996

Isolation and characterization of mutants as an approach to a transformation system in Kluyveromyces marxianus.

A method to obtain K. marxianus mutants has been developed. Different auxotrophic mutants were isolated by nystatin and snail-enzyme enrichment procedures using an incubation time of 2 h before adding the antibiotic or the enzyme respectively. All his mutants analyzed by complementation tests turned out to belong to the same complementation group. Some of them were transformed and complemented by the S. cerevisiae HIS3 gene. These non-reverting his3 mutants contain no heterologous sequence, which is essential to make them acceptable for application in the food industry.

Genes, Fungal↗
PubMed1995

Intraoperative radiation therapy in malignant glioma: early clinical results.

Intraoperative radiation therapy (IORT) with high energy electron beams is a treatment modality that has been included in multimodal programs in oncology to improve local tumor control. From August 1991 to December 1993, 17 patients with primary (8) or recurrent (9) high grade malignant gliomas, anaplastic astrocytoma (4), anaplastic oligodendroglioma (6) and glioblastoma multiforme (7), underwent surgical resection and a single dose of 10-20 Gy intraoperative radiation therapy was delivered in tumor bed. Fourteen patients received either pre-operative (8) or post-operative (6) external beam radiation therapy. Primary gliomas: 18-months actuarial survival rate has been 56% (range: 1-21+ months) and the median survival time has not yet been achieved. Four patients developed tumor progression (median time to tumor progression: 9 months). Recurrent gliomas: 18-months actuarial survival rate and median survival time has been 47% and 13 months (range: 6-32+ months) respectively. The median time to tumor progression was 11 months. No IORT related mortality has been observed. IORT is an attractive, tolerable and feasible treatment modality as antitumoral intensification procedure in high grade malignant gliomas.

Adolescent↗
PubMed1994

Efficient expression and secretion of recombinant alpha amylase in Pichia pastoris using two different signal sequences.

We have cloned and expressed a bacterial thermostable alpha amylase gene in Pichia pastoris using the methanol-controlled alcohol oxidase (AOX1) promoter. Two integrative vectors were constructed with two different secretion signal sequences in order to obtain efficient secretion of the protein. One vector contains the structural gene encoding the mature alpha amylase fused to the SUC2 gene signal sequence from Saccharomyces cerevisiae. In the other vector, the alpha amylase is expressed with its own signal sequence. In both cases, the alpha amylase were secreted into the culture medium with high efficiency, around 2.5 and 0.9 g/l respectively.

Alcohol Oxidoreductases↗
PubMed1993

Diffuse nodular regenerative hyperplasia of the liver associated with human immunodeficiency virus and visceral leishmaniasis.

We present a patient with human immunodeficiency virus (HIV) infection coincident with diffuse nodular regenerative hyperplasia (DNRH) of the liver and visceral leishmaniasis. This association has not been previously described. Some DNRH cases are secondary to irregular blood flow in the liver. In the presently described case, there exist two possible conditioning factors for heterogeneous distribution of blood flow: 1) the increased blood flow from splenomegaly, and 2) the irregular circulation of blood through sinusoids infiltrated by Leishmania-parasitized hyperplastic macrophages.

AIDS-Related Opportunistic Infections↗
PubMed1992

Cardiovascular reflexes in patients with malignant disease.

Although some authors have reported clinical features of autonomic dysfunction in patients with malignant disease only a few systematic studies have been carried out. We have investigated the autonomic function of 48 patients with carcinoma or lymphoma by testing their cardiovascular reflexes, and compared their results with those of 62 healthy volunteers. Our patients showed a smaller increase in heart rate and a greater fall in blood pressure on standing up, as well as a smaller rise in blood pressure in response to contralateral handgrip. The study group showed a higher percentage of established sympathetic lesion (54.2% vs 27.4%, p: 0.008) and of atypical pattern of global autonomic function impairment (50% vs 24.2%, p: 0.03) than the control group. Our data suggest that patients with malignant disease suffer from a definite autonomic dysfunction.

Aged↗
PubMed1990

Secretions of somatostatin and VIP in cultures of fetal rat neuroblasts increased by amino acids.

Neuroblasts obtained from 17 day old rat embryos were incubated for 8 days, after which half of them were treated with 10(-6) M FACE (a mixture of amino acids high in glycine, alanine and aspartic acid), and the other half were left as controls. At the end of 20 days, levels of somatostatin (SRIF) were over 6,000 pg/plate in neuroblasts treated with FACE, versus 500 pg/plate in controls. At this time vasoactive intestinal peptide (VIP) levels were over 230 pg/plate in the FACE treated cultures, while their controls contained less than 150 pp/plate. Protein totals were similar (about 1,000 micrograms/plate) in all FACE treated cultures and controls, indicating that increases in SRIF and VIP were not determined by changes in cell population, but by their synthetic and/or secretory activities triggered by minute amounts of FACE. These results may be of interest in the understanding of Alzheimer's disease.

Amino Acids↗
PubMed1990

Neurosecretory and trophic action on fetal rat neuroblasts induced by an amino acid mixture.

The effects of a synthetically obtained mixture of amino acids (FACE) were investigated on the trophic and neurosecretory activity of in vitro cultures of fetal rat neuronal cells. The addition of 10(-6) M FACE to the culture medium significantly increased cell DNA content. Secretions of IR-SRIF, IR-VIP, and IR-GRF were also augmented in different proportions by the presence of FACE. Time studies demonstrated that IR-SRIF was significantly increased after 48 (P less than 0.05) and 72 (P less than 0.01) hr of exposure to FACE, and IR-VIP secretion was potentiated after only 24 hr of culture. Dose-response experiments with 10(-7) to 10(-4) M FACE indicated that concentrations of 10(-5) and 10(-4) M significantly increased both somatostatin released to the medium and cell content of IR-SRIF. FACE concentrations as low as 10(-10) M augmented the secretion of IR-GRF, and there was a dose-response correlation between 10(-10) and 10(-5) M FACE. The release and cell content of IR-VIP were also increased by FACE, with a dose-response relation at concentrations of 10(-9) to 10(-6) M. It can thus be concluded that FACE has a powerful effect on the multiplication and survival of fetal cerebrocortical cells and is also an important potentiator of IR-SRIF, IR-VIP, and IR-GRF secretion.

Amino Acids↗