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A Flores

Publications and source records attributed to A Flores.

At least 109 records · Page 6Linked to original sources
PubMed1994

Analysis of Sec 19-1 mutant of Saccharomyces cerevisiae.

Saccharomyces cerevisiae Sec 19-1 cells are secretion mutants defective at 37 degrees C. The cells were analysed in order to ascertain the effect of mutation temperature on cell wall formation. At the restrictive temperature of 37 degrees C, the Sec 19-1 mutants had 37 micrograms/mg N-acetylglucosamine in the wall cells, while the wild type S. cerevisiae showed 84 micrograms/mg hexosamine. The mutants Sec 19-1 showed a maximum activity of chitin synthetase of 0.113 nmoles/min/ml, and the activity increased to 0.33 nmoles/min/ml in the wild type cells. On the other hand, variations of chitin distribution in the wall cells occurred at the restrictive temperature, but changes in actin organization were not evident. The results indicated that the mutation caused variations in the levels of N-acetylglucosamine and chitin synthetase, as well as in cell wall chitin distribution.

Actins↗
PubMed1993

Consensus guidelines for high dose rate remote brachytherapy in cervical, endometrial, and endobronchial tumors. Clinical Research Committee, American Endocurietherapy Society.

PURPOSE: A large number of medical centers have recently instituted the use of High Dose-Rate Afterloading Brachytherapy (HDRAB). There is wide variation in treatment regimens, techniques, and dosimetry being used and there are no national standard protocols or guidelines for optimal therapy. METHODS AND MATERIALS: The Clinical Research Committee (CRC) of the American Endocurietherapy Society (AES) met to formulate consensus guidelines for HDRAB in cervical, endometrial, and endobronchial tumors. CONCLUSION: Each center is encouraged to follow a consistent treatment policy in a controlled fashion with complete documentation of treatment parameters and outcome including efficacy and morbidity. Until further clinical data becomes available, the linear quadratic model can be used as a guideline to formulate a new HDR regimen exercising caution when changing from a Low Dose Rate (LDR) to a HDRAB regimen. The treatments should be fractionated as much as practical to minimize long term morbidity. As more clinical data becomes available, the guidelines will mature and be updated by the Clinical Research Committee of the AES.

Brachytherapy↗
PubMed1993

The pleiotropic effects of his overexpression in Salmonella typhimurium do not involve AICAR-induced mutagenesis.

Inhibition of cell division associated with overexpression of hisH and hisF in Salmonella typhimurium is strongly reminiscent of a cellular response to DNA damage. On these grounds, we investigated the involvement of a metabolite which appeared to represent a possible candidate for an endogenous mutagen: the base analog 5-amino-4-carboxamide imidazole riboside 5'-phosphate (AICAR), a by-product of HisH and HisF activity. However, we showed that AICAR is not an endogenous mutagen in S. typhimurium. Other types of DNA damage induced by his overexpression seem also unlikely, since similar mutation rates are found in hisO+ and hisOc strains. We also show that AICAR production is not involved in the pleiotropic effects of his overexpression, since these are still observed in strains devoid of AICAR. Thus inhibition of cell division resulting from HisH and HisF overexpression must operate through a mechanism unrelated to the role of these proteins in histidine biosynthesis.

Aminoimidazole Carboxamide↗
PubMed1993

Distribution of three retinal proteins in developing octopus photoreceptors.

The expression of proteins unique to plasma membrane domains of developing photoreceptors is used as a marker for retinal differentiation in vertebrates. Invertebrate photoreceptors are also compartmentalized, but little information is available on the development of these compartments or the expression of retinal proteins specific to these cellular regions. Using routine electron microscopy techniques, we have made observations on the formation of photoreceptor organelles, including myeloid bodies and rhabdomeres, in embryonic octopus eyes from an early stage in development through hatching. Immunocytochemical experiments on the embryos demonstrate a timed expression of three retinal proteins during development, and the early separation of the octopus photoreceptor plasma membrane into distinct domains. Using polyclonal antibodies for opsin, retinochrome and retinal binding protein we have shown that opsin appears first and is confined to the distal end of the photoreceptor that will eventually differentiate into rhabdomeres. This membrane domain is separated from the proximal/inner segment plasma membrane by a septate junction. Retinochrome is expressed later when the myeloid bodies appear in the inner segments, and retinal binding protein is apparently not synthesized until sometime after hatching. These results suggest that, in the cephalopod retina, protein components of the retinoid cycling apparatus appear in a specific developmental sequence during the differentiation of this tissue.

Animals↗
PubMed1993

Inhibition of programmed cell death by catalase and phenylalanine methyl ester.

1. Programmed cell death proceeds by an unknown mechanism which results in characteristic morphological changes known as apoptosis. 2. We have proposed that, in hormone-induced apoptosis, cell death may be the result of an attack of cells destined to die by cytotoxic macrophages. 3. We have investigated the effects of superoxide dismutase, catalase and the macrophage toxin, phenylalanine methyl ester, on the regression of tadpole tail slices in culture. 4. Our findings, that regression of bullfrog tadpole tails is blocked by catalase and phenylalanine methyl ester, support the working hypothesis.

Animals↗
PubMed1993

Electron microscopic identification of parvovirus virions in erythroid and granulocytic-line cells in a patient with human parvovirus B19 induced pancytopenia.

In this short report we describe a patient with human parvovirus B19 (HPV B19)-induced transient pancytopenia. Parvovirus virions were seen by electron microscopy in both erythroid and granulocytic precursors. Erythroid cells are not the only targets in these cases. We draw attention to this disorder so that physicians involved with hematological disorders and transplantation be more aware of this infection.

Adult↗
PubMed1993

Medico-legal reflexes of nurse and technician activity in hemapheresis practice.

The Author analyzes the role of nurse and technician in an hemapheresis équipe. Juridical and medico-legal aspects are evaluated on the basis of civil law and specific regulations now in force. The active role of physician in effective control of the apheretic treatment and also in a continuous up to date information and technical training of auxiliary personnel is emphasized.

Allied Health Personnel↗
PubMed1992

[Primary gastrointestinal lymphoma: a study of 25 cases].

BACKGROUND: The digestive tract constitutes the most frequent localization of the extranodular non Hodgkin's lymphoma. The chief clinical and histological characteristics were analyzed as were the evolution and response to treatment of 25 patients diagnosed with primary gastrointestinal lymphoma (PGIL) in one center over a period of eight years. METHODS: To establish the diagnosis of PGIL the Dawson criteria were used and the state was determined by the Ann-Arbor classification modified by Musshoff. To histologically classify of the PGIL the Working Formulation was followed. The influence of the clinical, histological characteristics and the state of the obtention of complete remission (CR), the survival free period of the disease (SFD) and global survival (GS) were analyzed. RESULTS: The mean age of the series was 56 years (standard deviation 15 years) (12 males). The most frequent localization was gastric followed by the small intestine and the large intestine. Abdominal pain and weight loss were the most frequent clinical manifestations in the PGIL, regardless of its site. In 12 patients the PGIL was of an intermediate grade of malignancy, 8 were of low grade and 5 of high grade. The state was IE in 11 patients, IE1 in 9 and IIE2 in 5. The most used treatment was radical surgery followed by polychemotherapy. Complete remission was obtained in 15 patients and 2 recurred. The foreseen SFP at 7 years was 69% of the cases and GS was 53%. In IE state patients was most frequently obtained and GS was also more prolonged in these patients. CONCLUSIONS: In the present series the gastric localization of patients with primary gastrointestinal lymphoma was more frequent than intestinal localization. The HNL of intermediate and high grades of malignancy predominated those of low grade. The prognosis of patients with primary gastrointestinal lymphoma in a IE state was more favorable than the remaining patients. In turn, surgery constituted a good option in the initial treatment of patients with primary gastrointestinal lymphoma.

Adult↗
PubMed1992

[Experience with 150 subcutaneous venous reservoirs for venous access and infusion for the treatment of adult patients with oncologic and hematologic disorders and acquired immunodeficiency syndrome].

BACKGROUND: In the present study the year experience of a multidisciplinary team (oncologic, unit for the acquired immunodeficiency syndrome, and surgery) with the use of a new method of central intravenous administration of medication such as that of subcutaneous venous reservoirs (SVR) is reviewed. METHODS: The subcutaneous injection capsules were implanted as a venous access in 150 surgical procedures in 146 patients from October 1985 to April 1991 with a total follow up of 29.190 days and a mean length of 251 days for SVR. Sixty-two percent (94 implantations) of the SVR were implanted in the out patient clinic, 20% (30 patients) were admitted for placement of the reservoir although this was only indicated in the first two years of the series, 13% (20 patients) during hospitalization for the base disease and only 4% (6 patients) were specifically admitted for surgical preparation (plasma, platelets, and others). SVR were used for chemotherapy (124 cases, 82%), repeated transfusions (6 cases, 4%) and chronic medication (acquired immunodeficiency syndrome, infections) (30 patients, 20%). Forty-two percent permitted chemotherapy administration by continual transfusion on an out patient regime. RESULTS: A series of mechanical complications (3 cases, 2%), septic (9 episodes in 7 patients, 5%) and thrombotic (8 of the catheter) (5%) and 4 of the central veins (2%) were observed. In the present series the rate of infections (5%) (0.072 episodes of bacteremia per 100 days/patient) and thrombosis (3%) was very low due to a strict protocol of maintenance and control by the medical team and hospital staff. The need for radiologic control during surgery is emphasized although, as demonstrated in the present review, the technique of localization by a cath-finder (external detector) permits greater speed with the same security. CONCLUSIONS: The degree of patient satisfaction and the minimum incidence of serious complications in determined risk groups (neutropenia, acquired immunodeficiency syndrome) demonstrates that subcutaneous venous reservoirs (SVR) constitute an excellent method as a chronic venous access. The SVR present a lower rate of complications if compared with any historic series of external vascular catheterization.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Immunocytochemical localization of retinal binding protein in the octopus retina: a shuttle protein for 11-cis retinal.

The cephalopod retina contains two photopigments that are spatially separated within the photoreceptors; rhodopsin, localized in the light-sensitive rhabdoms, and retinochrome, present in the myeloid bodies of the photoreceptor inner segments. In the light, the chromophore of retinochrome, all-trans retinal, is photoisomerized to 11-cis to form metaretinochrome. Metaretinochrome is believed to serve as a store for 11-cis retinal used in the regeneration or biosynthesis of rhodopsin. Previous studies suggest that a soluble retinal binding protein (RALBP) serves as a shuttle between retinochrome and rhodopsin, and, in the dark, may transport chromophore from the myeloid bodies to the rhabdoms. Our study supports this hypothesis and demonstrates that RALBP is in the correct cellular locations to function as a shuttle. Dark- and light-adapted octopus retinas were labeled with anti-RALBP using immunofluorescence and immunogold techniques. Our results showed that RALBP was distributed differently in the dark- and light-adapted retinas. Our most significant observation was that myeloid bodies from light-adapted retinas were more heavily labeled by anti-RALBP than myeloid bodies in dark-adapted retinas. The rhabdomeres, interphotoreceptor matrix, and inner limiting membrane were also labeled in both light and dark conditions. Based on these results and evidence from previous biochemical studies, we conclude that in the dark RALBP leaves the myeloid bodies and transports 11-cis retinal to the rhabdoms where chromophore exchange with metarhodopsin may occur.

Adaptation, Ocular↗
PubMed1992

Inhibition of programmed cell death by cyclosporin.

1. Apoptosis is generally believed to occur as a consequence of activation of an internal, genetically controlled, program in the dying cells. 2. We have proposed an alternative hypothesis that, in hormone-induced apoptosis, the active participation of dying cells in the death process may be limited to expressing surface proteins that permit identification of cells destined to die by cytotoxic effector cells. 3. We investigated the effects of the immunosuppressant, cyclosporin, and the lysosomotropic agents, chloroquine and N-ethyl maleimide on thyroid hormone-induced regression of the bullfrog tadpole tail. 4. All three substances blocked regression. These results suggest that patency of the intracellular protein trafficking machinery is essential for programmed cell death in our system.

Animals↗
PubMed1992

Tetracycline-induced esophagitis in adolescent patients.

Ulcerative esophagitis may be caused by corrosive agents and by commonly prescribed medications. We report severe esophagitis in five adolescents after ingestion of tetracycline preparations with minimal water immediately before going to bed.

Adolescent↗
PubMed1992

Molybdenum cofactor (chlorate-resistant) mutants of Klebsiella pneumoniae M5al can use hypoxanthine as the sole nitrogen source.

Selection for chlorate resistance yields mol (formerly chl) mutants with defects in molybdenum cofactor synthesis. Complementation and genetic mapping analyses indicated that the Klebsiella pneumoniae mol genes are functionally homologous to those of Escherichia coli and occupy analogous genetic map positions. Hypoxanthine utilization in other organisms requires molybdenum cofactor as a component of xanthine dehydrogenase, and thus most chlorate-resistant mutants cannot use hypoxanthine as a sole source of nitrogen. Surprisingly, the K. pneumoniae mol mutants and the mol+ parent grew equally well with hypoxanthine as the sole nitrogen source, suggesting that K. pneumoniae has a molybdenum cofactor-independent pathway for hypoxanthine utilization.

Chromosome Mapping↗
PubMed1992

Noradrenergic peripheral denervation of the female rat accelerates the positive feedback mechanisms resulting in pubertal ovulation, and blocks the modifications induced by administration of testosterone propionate at birth.

The noradrenergic innervation of the ovary of prepubertal rats causes an inhibitory response of the follicles to gonadotrophins, leading to ovulation. We investigated the possibility that noradrenergic peripheral denervation at birth, produced by treatment with guanethidine, modifies the positive feedback effects of gonadotrophins and oestradiol in prepubertal rats, and also the possibility that peripheral denervation can modify the anovulatory syndrome induced by androgenization at birth. Noradrenergic peripheral denervated rats of 18 days of age treated with pregnant mare serum gonadotrophin (PMSG) ovulated 96 h later, while normal animals did not ovulate (4/9 vs 0/12, P < 0.05) and the number of ova shed was lower than in rats which ovulated spontaneously at first vaginal oestrus (3.5 +/- 0.6 vs 8.3 +/- 0.4 (S.E.M.), P < 0.01). Oestradiol benzoate (10 micrograms) did not induce ovulation in either normal or denervated animals (0/11 and 0/11). The anovulatory syndrome induced by the administration of testosterone propionate (75 micrograms) at birth was partially blocked by noradrenergic peripheral denervation (4/7 ovulated vs 0/10). The results suggest that some neural information arising from the ovary modulates, in an inhibitory way, the stimulatory feedback mechanisms required to induce ovulation. Partial inhibition of the anovulatory syndrome resulting from androgenization caused by peripheral noradrenergic denervation suggests that noradrenergic neural information sent by the ovary to the hypothalamus results in a decreased concentration of noradrenaline in the hypothalamus and in the aromatization of androgens to oestrogens.

Animals↗
PubMed1992

[Effects of stress on relative leukocyte frequency and serum sodium and potassium concentrations in bovines].

The leucocyte and mineral profile changes were studied in bovines with different waiting time at the slaughterhouse. The stress induced by the waiting time at the slaughterhouse brought changes in relative leukocyte frequency, with inverted neutrophil:lymphocyte relation in animals with 24 hours of waiting time (1.45). However the sodium:potassium relation in the animals with 48 hours of waiting time was significantly lower (23.6, p < 0.001) than that almost normal in animals with 24 hours of waiting time (33.1). Also the high correlations between the parameters studied show an unique physiological or pathological situation. The found values point out hormonal changes similar to those in stress situations.

Abattoirs↗
PubMed1992

[Plasma cell leukemia. Study of 6 patients].

PURPOSE: To analyse the clinico-biological characteristics, the clinical course and the response to therapy in a group of patients with plasma cell leukaemia (PCL). MATERIAL AND METHODS: Out of a total number of 107 patients diagnosed of multiple myeloma (MM) between 1983 and 1991, 6 were found to meet the criteria for PCL (prevalence: 5.6%). This was primary in 2 cases and secondary in the remaining 4. The M/F ratio was 2/1 and the median age was 63 years (range: 57-69 years). RESULTS: Two patients had bone pain and two others weight loss at the onset of PCL. The outstanding haematological findings were increased ESR, normocytic-normochromic anaemia and thrombocytopenia, which were present in all cases. The percentage of peripheral blood plasma cells was between 29 and 70, and the bone marrow aspirate showed plasma cell infiltration over 40% in all cases. Serum M component was found in 5 patients, with decreased values of the polyclonal immunoglobulins; the remaining patient had non-secretory MM. Renal insufficiency was present in 3 patients at diagnosis. Three of the 4 patients with secondary PCL had been previously given combination chemotherapy and the remainder had received melphalan and prednisone. The period between the diagnosis of MM and the development of PCL ranged between 1 and 21 months (median 15 months). Three patients were treated with the M-2 protocol and the others received only supportive therapy. Transient partial response could be achieved in only one case with chemotherapy. All the patients have died, the actuarial survival median being 1 month (range, 1-7 months). Three patients died of infection, 2 of renal insufficiency and one of heart failure after acute myocardial infarction. CONCLUSION: The poor prognosis of PCL was confirmed, along with the scarce response to therapy of these patients.

Aged↗
PubMed1992

Diversion colitis in children with severe gastrointestinal motility disorders.

We found colitis in 11 of 14 children, 4 months to 7 yr after surgical diversion of the colon for chronic intestinal pseudo-obstruction. Colonoscopic examination was incidental during placement of a catheter for colon manometry and transit studies. All 14 children had complained of diffuse, poorly localized abdominal pain, but only three had a history of bloody stools. Diversion colitis had not previously been suspected in six of eight affected children without hematochezia. Biopsies showed a nonspecific acute and chronic inflammation and/or nodular lymphoid hyperplasia. There was no correlation between the duration of the colonic diversion and the severity of the colitis. Diversion colitis may be an indolent inflammatory nidus and a potential cause for repeated bacteremia, abdominal pain, and bleeding.

Child↗