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Schenone H, Contretras MC, Salinas P, Sandoval L, Saavedra T, Rojas A. Seroprevalence of hydatidosis in Chile. Parasitol Int 1998. [DOI: 10.1016/s1383-5769(98)80398-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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152
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Chatterjee A, Rojas A, Hodgkiss RJ. Induction of lethal mutations in experimental tumours after single and fractionated irradiations in vivo. Int J Radiat Biol 1998; 74:119-27. [PMID: 9687981 DOI: 10.1080/095530098141780] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
PURPOSE To investigate the prolonged reduction in cellular viability (lethal mutations) of surviving cells following irradiation of tumours in vivo and to test the effects of fractionation on the expression of lethal mutations. MATERIALS AND METHODS A mouse mammary carcinoma (CaNT) was treated with single dose or fractionated X-ray treatments in vivo and survival quantified with an in vitro excision assay soon after irradiation and at various times up to 35 days after in vitro propagation of the surviving cells. RESULTS A dose-dependent reduction in the plating efficiency was observed in cells isolated from irradiated tumours up to 35 days and many cell generations after irradiation. Considerable heterogeneity in plating efficiency was observed in clonal cell lines isolated from individual colonies grown from irradiated tumours. Delayed expression of lethal damage was observed after fractionated irradiation, although recovery of cellular fitness was greater than after irradiation with single doses (reported previously) suggesting that this form of damage is affected by inter-fraction repair. At equi-toxic doses, delayed expression of lethal damage was similar after three compared with two fractions of radiation per day (reported previously). CONCLUSIONS These effects indicate that conventional excision assays of tumour cell viability under-estimate the total lethal damage caused by irradiation and have implications for modelling of the response of tumours to radiotherapy. The effect of fractionation on expression of this type of damage implies the involvement of repair processes. Therefore the repair proficiency may affect the balance between the immediate and delayed reduction of viability in irradiated cells.
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Arteaga E, Villaseca P, Rojas A, Arteaga A, Bianchi M. [Comparison of the antioxidant effect of estriol and estradiol on low density lipoproteins in post-menopausal women]. Rev Med Chil 1998; 126:481-7. [PMID: 9731428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
BACKGROUND Estradiol (E2) has a potent antioxidant effect on low density lipoproteins (LDL) in vitro and in vivo, which could be important in explaining the cardioprotective effect of hormone replacement therapy (HRT) in post menopausal women. Estriol (E3), on the other hand, is a weak estrogen with low metabolic effects on different tissues, and at present no cardioprotective effect has been attributed to this steroid. AIM To study the antioxidant effect of E3 on LDL and to compare it with the potent antioxidant action exhibited by E2. SUBJECTS AND METHODS After LDL was isolated by ultra centrifugation from plasma of 12 healthy untreated post menopausal women, it was divided into aliquots containing 0.5 mg of LDL protein. Estriol and E2 in doses of 0, 1, 5, 15 and 50 microM were incubated with different aliquots of LDL. CuSO4 15 microM was added to each aliquot to induce an oxidative stress. The aliquots were then incubated during 4 hours at 37 degrees C. Malonaldehyde (MDA) was measured as a marker of LDL oxidation, and expressed as nM/mg protein. RESULTS (mean +/- SD): Estriol induced a dose-dependent decrease in MDA concentration (baseline 62.8 +/- 21.7; 1 microM: 61.5 +/- 23.0; 5 microM: 52.9 +/- 20.3; 15 microM 43.5 +/- 20.1 and 50 microM: 31.0 +/- 17.6 nM/mg protein; F = 92.4; p < 0.0001), reaching a mean decrease of 50.7% at the highest dose tested. Estradiol has a similar dose-dependent decrease in MDA concentration (F = 60.2; p < 0.0001), revealing a more potent effect than E3 (p < 0.05), with a mean decrease of 67.4% at the highest dose tested. CONCLUSIONS Our results demonstrate that estriol shows an important antioxidant action of LDL in vitro, although its effect is less potent than estradiol. These results raise the possibility that estriol could have a cardioprotective effect in post menopausal women, possibility that has not been yet demonstrated.
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García-Vallvé S, Rojas A, Palau J, Romeu A. Circular permutants in beta-glucosidases (family 3) within a predicted double-domain topology that includes a (beta/alpha)8-barrel. Proteins 1998; 31:214-23. [PMID: 9593194 DOI: 10.1002/(sici)1097-0134(19980501)31:2<214::aid-prot10>3.0.co;2-j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
By predicting the general secondary structure for beta-glucosidases (family 3), in conjunction with existing knowledge of the circular permutants present in B. fibrisolvens and R. albus, we were able to find the canonical elements of the secondary structure. The way these elements are linked suggests that there is a double-domain topology made up of a (beta/alpha)8-barrel domain and a "mainly all-beta" domain. A number of already known conserved motifs are located within (or near) the C-terminal part of the putative parallel beta-strands of the (bet/alpha)8-barrel, which is consistent with what is known about the location of catalytical sites for enzymes that have this domain topology. Within the circular permutants, two beta/alpha units are located at the N-terminal part of the molecule, whereas the other six beta/alpha units are located at the C-terminal end. In this way, the circular permutants can be seen to have a putative discontinuous double-domain topology.
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López-Collazo E, Hortelano S, Rojas A, Boscá L. Triggering of peritoneal macrophages with IFN-alpha/beta attenuates the expression of inducible nitric oxide synthase through a decrease in NF-kappaB activation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 1998; 160:2889-95. [PMID: 9510192 DOI: pmid/9510192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Triggering peritoneal macrophages with IFN-gamma and a low concentration of LPS induced the expression of the inducible form of nitric oxide synthase (iNOS). This process was significantly inhibited when IFN-alpha/beta was added during the initial 2 h after the start of IFN-gamma/LPS activation. Evaluation of the transcriptional activity using run-on assays indicated that IFN-alpha/beta inhibited the transcription of iNOS. Transfection experiments using a 1.7-kb promoter sequence corresponding to the 5' flanking region of the murine iNOS gene showed decreased promoter activity in the presence of type I IFNs. Analysis of the transcription factors that participate in iNOS expression revealed a marked decrease of NF-kappaB activation, a nuclear factor required for the transcription of this gene. The degradation of IkappaB alpha and IkappaB beta, which is required for the translocation of NF-kappaB to the nucleus, was inhibited in the presence of IFN-alpha/beta. However, the activity of other transcription factors such as IFN regulatory factor 1, which is involved in the expression of iNOS in response to IFN-gamma, was not affected by IFN-alpha/beta stimulation. These results suggest that in the presence of IFN-alpha/beta, the activity of the iNOS promoter is impaired, and this attenuated nitric oxide synthase expression could be important in pathophysiologic situations in which secretion of type I IFNs occurs.
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Kaanders JH, Stratford MR, Liefers J, Dennis MF, van der Kogel AJ, van Daal WA, Rojas A. Administration of nicotinamide during a five- to seven-week course of radiotherapy: pharmacokinetics, tolerance, and compliance. Radiother Oncol 1997; 43:67-73. [PMID: 9165139 DOI: 10.1016/s0167-8140(96)01896-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND AND PURPOSE Nicotinamide was administered daily as a liquid formulation to head and neck cancer patients receiving a 5- to 7-week course of radiotherapy. The pharmacokinetics, compliance, and tolerance of this drug formulation were studied. MATERIALS AND METHODS Blood samples were drawn and nicotinamide levels determined in 40 head and neck cancer patients. On the first treatment day serial samples were obtained followed by daily samples at the time of irradiation during the first and last full weeks of the treatment. Side-effects of nicotinamide were monitored. RESULTS In all patients peak concentrations greater than 700 nmol/ml could be obtained 0.25-3 h (mean 0.83 +/- 0.73 h) after drug intake. During the first week of treatment plasma levels at the time of irradiation were adequate in 82% of the samples. This decreased to 59% in the last week of treatment which can be partly attributed to reduced compliance. The most important side-effect of nicotinamide was nausea with or without vomiting occurring in 65% of the patients. Severe side-effects were associated with high plasma concentrations over subsequent days. Tolerance improved after a 25% reduction of dose in six of seven patients but plasma levels at the time of irradiation fell below 700 nmol/ml in four out of six of these patients. CONCLUSIONS Peak plasma concentrations above the 700 nmol/ml level were obtained in all patients but these concentrations could not be reproduced during the entire course of the treatment in a significant portion of the subjects. Side-effects of nicotinamide are associated with plasma concentrations and tolerance can be improved by a moderate reduction of dose.
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González S, Casado I, Rojas A. [Evaluation of the record of preventive activities of adolescents in a health district]. Aten Primaria 1997; 19:271-2. [PMID: 9264659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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Mata R, Rojas A, Acevedo L, Estrada S, Calzada F, Rojas I, Bye R, Linares E. Smooth muscle relaxing flavonoids and terpenoids from Conyza filaginoides. PLANTA MEDICA 1997; 63:31-35. [PMID: 9063094 DOI: 10.1055/s-2006-957598] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Activity-guided fractionation of the smooth muscle relaxing, chloroform-methanol (1:1) extract of Conyza filaginoides (D.C.) Hieron (Asteraceae) led to the isolation of three flavonoids (quercetin 3-glucoside, rutin, and pinostrobin), one sterol (alpha-spinasterol), a sesquiterpenoid (beta-caryophyllene 4,5-alpha-oxide), and two triterpenoids (erythrodiol and 3-beta-tridecanoyloxy-28-hydroxyolean-12-ene). 3-beta-Tridecanoyloxy-28-hydroxy-olean-12-ene is a new naturally occurring terpenoid. All the isolated compounds induced a concentration-dependent inhibition of the spontaneous contractions of rat ileum. The spasmolytic activity exhibited by the extract and active principles tends to support the traditional use of C filaginoides as an antispasmodic agent.
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Hoskin PJ, Saunders MI, Phillips H, Cladd H, Powell ME, Goodchild K, Stratford MR, Rojas A. Carbogen and nicotinamide in the treatment of bladder cancer with radical radiotherapy. Br J Cancer 1997; 76:260-3. [PMID: 9231929 PMCID: PMC2223941 DOI: 10.1038/bjc.1997.372] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Carbogen and nicotinamide have been evaluated in a phase II study as hypoxia-modifying agents during radical radiotherapy for bladder cancer using a standard daily 20-fraction schedule. Three groups of patients have received (a) nicotinamide alone, given orally in a dose of 80 mg kg(-1) daily with 52.5 Gy in 20 fractions over 4 weeks, (b) carbogen alone, with 50 Gy in 20 fractions over 4 weeks, and (c) carbogen and nicotinamide, with 50-52.5 Gy in 20 fractions over 4 weeks. Ten patients were treated in each group. All patients completed carbogen and radiotherapy as prescribed, but only 45% completed daily nicotinamide over the 4-week treatment period. The end points of this study were acute bowel and bladder morbidity and local control at cystoscopy 6 months after treatment. An expected level of acute bowel and bladder morbidity was seen that reverted to normal in most patients by 12 weeks with no difference between the three treatment groups. Complete response rates at 6 months were seven out of ten (100%) in the nicotinamide alone group, nine out of ten (90%) in the carbogen alone group and seven out of ten (70%) in the carbogen and nicotinamide group. It is concluded that carbogen and nicotinamide may improve the results of daily fractionated radiotherapy in bladder cancer and that further evaluation is required.
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Fardella CE, Rodriguez H, Montero J, Zhang G, Vignolo P, Rojas A, Villarroel L, Miller WL. Genetic variation in P450c11AS in Chilean patients with low renin hypertension. J Clin Endocrinol Metab 1996; 81:4347-51. [PMID: 8954040 DOI: 10.1210/jcem.81.12.8954040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Low renin hypertension (LRH), which accounts for 10-20% of patients with idiopathic "essential" hypertension, bears hormonal similarities to mineralocorticoid-induced hypertension, but elevated mineralocorticoid concentrations have not been found. Some patients with LRH have normal, rather than suppressed, plasma aldosterone concentrations, so that the ratio of aldosterone concentration to PRA (Aldo/PRA) is high, suggesting inappropriately increased aldosterone biosynthesis. We characterized the CYP11B2 gene that encodes the aldosterone synthase, P450c11AS, in hypertensive and control populations in a single clinic in Santiago, Chile. We directly sequenced the entire CYP11B2 gene in 12 patients with LRH, 2 high renin hypertensive controls, and 2 normotensive controls. All sequences were identical, except that 8 of 24 LRH alleles encoded arginine rather than lysine at position 173. The Arg173 and Lys173 variants were expressed in transfected MA-10 cells, and their ability to convert deoxycorticosterone to aldosterone was measured; the apparent Michaelis constant (Km) for Lys173 was 2.73 mumol/L; the Km for Arg173 was 2.53 mumol/L. The apparent maximal velocity (Vmax) for Lys173 was 6.5 x 10(-3) micrograms/mL.24 h; the Vmax for Arg173 was 7.8 x 10(-3) micrograms/mL.24 h. The first order rate constant, Vmax/Km was 2.38 for Lys173 and 3.08 for Arg173. As these values were not significantly different, we sought to determine whether Arg173 is a polymorphism linked to LRH. We examined position 173 in 52 unselected patients with idiopathic hypertension and 55 normotensive controls by PCR amplification of CYP11B2 exons 3-5 followed by digestion with Bsu361, which digests the Arg173 sequence, but not the Lys173 sequence. More of the hypertensive alleles (39 of 104, 37.5%) than normotensive alleles (25 of 110, 22.5%) carried Arg173 (chi 2 = 5.57; P < 0.02). Most of the Arg173 alleles (31 of 72, 43.1%) were from hypertensive patients with Aldo/PRA below 30, whereas only 5 of 24 (20.8%) Arg173 alleles were found in patients with Aldo/PRA greater than 30 (chi 2 = 3.79; P = 0.05) Thus, the ARg173 variant of CYP11B2 may be linked to LRH in Chilean patients.
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Villaseca P, Arteaga E, Campusano C, López JM, Rojas A, Nazar G, O'Brien A. [Effects of hormone replacement therapy in bone resorption, in post-menopausal women]. Rev Med Chil 1996; 124:1439-46. [PMID: 9334477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The effects of different therapies on bone loss rate can be measured using biochemical markers of bone resorption such as urinary hydroxyproline. AIM To study the effects of hormone replacement therapy on urinary hydroxyproline in postmenopausal women. PATIENTS AND METHODS Eighty three postmenopausal women without hormone replacement therapy, 54 postmenopausal women receiving hormone replacement therapy and 16 premenopausal women (considered as the control group) were studied. Hydroxyproline was measured in an early morning urine sample, after one day of diet without meat or gelatin. RESULTS Urinary hydroxyproline in premenopausal women was 33.7 +/- 7.9 mg/g creatinine. The figure for postmenopausal women with hormonal replacement therapy was 33.7 +/- 5.9 mg/g creatinine. Postmenopausal women without replacement therapy had an urinary hydroxyproline of 47.4 +/- 8.5 mg/g creatinine, significantly higher than that of premenopausal and supplemented women. In 21 postmenopausal women, hydroxyproline was measured before and after three months of replacement therapy, values decreased 35.5 +/- 11% in this period and there was a direct correlation between initial values and the degree of reduction (r = 0.69, p < 0.001). CONCLUSIONS Postmenopausal women receiving hormone replacement therapy have a urinary hydroxyproline excretion similar to that of premenopausal women.
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Rojas A, Romeu A. 3'-flanking region of a family 1 beta-glucosidase gene. Biochem J 1996; 320 ( Pt 2):693-4. [PMID: 8973586 PMCID: PMC1217985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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Arteaga E, Rojas A, Villaseca P, Pérez L, López JM, Rodríguez L, Campino C. [Dissolution velocity of different calcium preparations used in the clinical field]. Rev Med Chil 1996; 124:1325-33. [PMID: 9293097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Prescription of calcium supplements is a frequent practice, considering that diet is insufficient to cover daily requirements of this mineral. AIM To study the dissolution velocity in an acid solution, of different commercial calcium supplements. MATERIAL AND METHODS Hydrochloric acid was added to distilled water in increasing amounts to obtain a final pH of 6.9, 3.0, 2.5, 2.0 and 1.5. Eighteen commercial calcium preparations were incubated in these solutions for 60 min and dissolution velocity was measured as the percentage of elemental calcium found in solution after this incubation period. RESULTS Calcium carbonate preparations had a pH dependent dissolution velocity, ranging from 0.67 +/- 0.8% at pH 6.9 to 77.15 +/- 17.5% at pH 1.5. Using the solution with pH 1.5, the dissolution velocity of different preparations varied widely from 56 to 100%. Calcium acetate, followed by calcium citrate and dicalcic phosphate were the salts in tablets with better dissolution velocities. Among powders and effervescent preparations, those containing calcium lactogluconate and citrate had the better dissolution velocities (95 to 115%), that were independent of the solution's pH. A studied preparation with integral bone had a very low dissolution velocity, not surpassing 33 mg of calcium per tablet. CONCLUSIONS The dissolution velocity of different calcium carbonate preparations varies greatly and, in conditions of achlorhydria, it is negligible. Calcium lactogluconate and citrate dissolution velocities are independent of the solution's pH.
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Gutiérrez M, Rioseco F, Rojas A, Casanova D. [Determination of spirometric values in a normal Chilean population over 5 years old, at sea level]. Rev Med Chil 1996; 124:1295-306. [PMID: 9293093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND The interpretation of spirometric results requires reference values. Up to the moment, the reference values used in Chile are those of Knudson et al, obtained in a white North American population studied in Tucson, USA. AIM To obtain reference spirometric values from a Chilean population. SUBJECTS AND METHODS Maximal expiratory flow-volume curves were obtained from a randomly selected population of 850 healthy non-smoking subjects living at sea level, in cities without atmospheric pollution. Equipment and techniques were used according to the recommendations of the American Thoracic Society. RESULTS Linear regression equations were obtained, using age and height as independent variables and spirometric values as dependent variables, for both sexes and ages from 6 to 70 years old. Our values for forced vital capacity and forced expiratory volume were 9 to 18% and 10 to 15% higher than those reported by Knudson et al. CONCLUSIONS Chilean spirometric reference values differ from those used abroad, emphasizing the need to use local standards to interpret spirometric results.
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Contreras M, Schenone H, Salinas P, Sandoval L, Rojas A, Villarroel F, Solis F. Seroepidemiology of human toxoplasmosis in Chile. Rev Inst Med Trop Sao Paulo 1996; 38:431-5. [PMID: 9293090 DOI: 10.1590/s0036-46651996000600008] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A series of already published and unpublished seroepidemiological surveys for toxoplasmosis, carried out in Chile in 1982-1994, is reviewed, expanded and analyzed. The surveys included 76,317 apparently healthy individuals of different ages (0.57% of the country's total population), from 309 urban and rural-periurban localities. Urban groups were integrated by blood donors, delivering mothers and middle grade schoolchildren, while rural-periurban individuals corresponded to unselected family groups. Blood samples were collected in filter paper. The presence of antibodies to Toxoplasma gondii was determined by the indirect hemagglutination test (IHAT), titers > or = 16 were considered positive. The test resulted positive in 28,124 (36.9%) of the surveyed people. Two hundred and six (0.3%) individuals presented IHAT titers > or = 1000, probably corresponding to acute or reactivated infections. A progressive increase of positive IHAT from northern to southern regions of the country was noted, phenomenon probably related to geographical conditions and to a higher production and consumption of different types of meat in the latter regions. It is postulated that ingestion of T gondii cysts by humans is epidemiologically as important as ingestion of oocysts. The result presented stress the epidemiological importance of toxoplasmosis in humans, and warn about eventual implications in immunocompromised patients and in transplacental transmission, organ transplants and transfusions.
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Rojas A. ARCON. Strahlenther Onkol 1996; 172 Suppl 2:34-5. [PMID: 8946047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
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167
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Rojas A, Caveda L, Romay C, López E, Valdés S, Padrón J, Glaría L, Martínez O, Delgado R. Effect of advanced glycosylation end products on the induction of nitric oxide synthase in murine macrophages. Biochem Biophys Res Commun 1996; 225:358-62. [PMID: 8753769 DOI: 10.1006/bbrc.1996.1180] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We studied the role of advanced glycosylation end products on the induction of nitric oxide synthase in peritoneal mouse macrophages previously exposed to modified BSA. A dose-dependent increment in the nitric oxide production induced by LPS and IFN-gamma was observed when cell cultures were pretreated with modified BSA for 48 hours. In addition, the up regulation of nitric oxide production was also time-dependent, being maximal at 24-48 hours. Experiments carried out in the presence of neutralizing antibodies to IL-1 and TNF-alpha, suggested that up regulation was not due to the capacity of modified BSA to induce both proinflammatory signals. The up regulation of nitric oxide production was paralleled with an increase in iNOS mRNA.
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Lorca M, Schenone H, Contreras MC, García A, Rojas A, Valdés J. [Evaluation of vectors of Chagas' disease eradication programs in Chile by serological study of children under 10 years old]. BOLETIN CHILENO DE PARASITOLOGIA 1996; 51:80-5. [PMID: 9302780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chagas' disease is a parasitic zoonosis with high prevalence in Chile. It is distributed in rural and periurban section in the northern most seven out of thirteen regions in which the country is divided, and affects about 142,000 individuals dispersed in most of the 165 counties sited in the chagasic zone. Triatoma infestans--intradomiciliary species--is the main and practically exclusive vector of Trypanosoma cruzi. Diverse tools may be utilized in order to interrupt the domestic cycle of transmission of T. cruzi: health education, housing improvement and elimination of vectors by dwelling insecticide sprayings. This last resource has received priority in Chile in the last 12 years. To evaluate the effectivity of the programs for eliminating T. infestans a serological study for Chagas' disease--comprising 8,767 children less than 10 years old from 27 rural counties insecticide sprayed in the last 12 years--was carried out. A global total of 125 (1.4%) children resulted positive, figure significantly lower than 5.4% found in 1982-1990 in the same age group. Distribution by regions of positive individuals showed a decrease of prevalence in each of them: III Region, from 9.8 to 1.0%, IV Region, 7.2 to 2.0%, V Region, 5.2 to 1.9%, and Metropolitan Region, 1.4% to 0.6. Even though positive children have still been found in 46.7% of localities of the studied counties, it is possible to affirm that the vector control programs have been effective and must be maintained, and increased in those localities with T. cruzi infection in children under 10 years of age, with the general aim of eradicate Chagas' disease transmission in Chile before 2000.
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Stratford MR, Dennis MF, Hoskin P, Phillips H, Hodgkiss RJ, Rojas A. Nicotinamide pharmacokinetics in humans: effect of gastric acid inhibition, comparison of rectal vs oral administration and the use of saliva for drug monitoring. Br J Cancer 1996; 74:16-21. [PMID: 8679452 PMCID: PMC2074616 DOI: 10.1038/bjc.1996.309] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The effect of inhibiting gastric acid secretion on nicotinamide pharmacokinetics was studied in five volunteers with the intent of reducing the large variations observed previously in the time to and magnitude of peak plasma concentrations. Plasma levels were determined using a standard high-performance liquid chromatography (HPLC) method after an oral dose of 3 g of nicotinamide either alone or preceded by pretreatment with omeprazole. Suppression of gastric acid production had no significant effect on the rate of uptake or on the peak levels achieved. To bypass gastric acidity, the rectal route was also assessed using a suppository in four volunteers and one patient undergoing radiotherapy. Absorption was slow and variable and much lower plasma levels were observed than after oral dosing. Thus, no improvement in the pharmacokinetics of nicotinamide was observed using either of these two approaches. Parallel estimations were made using a novel and non-invasive method for monitoring nicotinamide pharmacokinetics in saliva. A large and variable fraction of the total amount of nicotinamide-related material in saliva was found to be nicotinic acid, a metabolite not normally found in human plasma. This conversion was inhibited by the use of a chlorhexidine mouthwash, indicating that the oral flora was responsible for its production. The time to peak levels of nicotinamide or of nicotinamide plus nicotinic acid in saliva correlated well with that in plasma. However, peak concentrations for nicotinamide alone were significantly lower than in plasma, and very variable, whereas for nicotinamide plus nicotinic acid saliva levels were 20-30% higher, but more consistent. Although there are some practical difficulties in quantitatively handling saliva, the method is very useful for monitoring nicotinamide pharmacokinetics and for assessment of compliance with nicotinamide treatment.
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Van Herreweghe I, Benatar A, Danschutter D, Ramet J, Kirby F, Whyte P, Mannion D, Butler K, Casey WF, Tóth-Urbán K, Wintsche Z, Leclerc F, Cremer R, Fourier C, Martinot A, Leteurtre S, Hue V, Jude B, Mikos B, Biró É, Glaría LA, Tamayo D, Torres M, Domínguez F, Santurium M, González I, Martínez O, Padrón J, Rojas A, von Rosenstiel IA, Vreede WB, Lewis MA, Grinenko DV, Grinenko EP, Ivaschenko TO, Zhurilo IP, Brajkovic Z, Maksimovic D, Vunjak N, Milikic V, Jovanovic I, Ivanovski P, Kruscic D. Sepsis. Intensive Care Med 1996. [DOI: 10.1007/bf03216393] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Rojas A, Denekamp J, Johns H, Kjellen E, Tsang R, Nilsson P, Stratford MRL, Dennis MF, Joiner MC. Nicotinamide as a Repair Inhibitor In Vivo: Studies Using Single and Fractionated X-Ray Doses in Mouse Skin and Kidneys. Radiat Res 1996. [DOI: 10.2307/3579063] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Rojas A, Belhaji I, Rivas J. [Massive heart herniation after intrapericardial radical pneumonectomy]. REVISTA ESPANOLA DE ANESTESIOLOGIA Y REANIMACION 1996; 43:153. [PMID: 8815475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Rojas A, Denekamp J, Johns H, Kjellen E, Tsang R, Nilsson P, Stratford MR, Dennis MF, Joiner MC. Nicotinamide as a repair inhibitor in vivo: studies using single and fractionated X-ray doses in mouse skin and kidneys. Radiat Res 1996; 145:419-31. [PMID: 8600502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Inhibitors of adenosine diphosphoribosyl transferase, like nicotinamide, 3-aminobenzamide and other analogues, can inhibit repair of radiation-induced sublethal and/or potentially lethal damage in some in vitro systems. Therefore, we have tested the effect of nicotinamide on repair parameters in vivo in two rodent normal tissues. In skin, the sensitivity to dose fractionation (1, 2, 5 or 10 X-ray fractions in 5 days) was monitored by defining the alpha/beta ratio in the presence or absence of nicotinamide (0.5 mg g-1) in air or carbogen. Pre- and postirradiation sensitization were investigated using an X-ray schedule of 5 fractions/5 days in carbogen alone or combined with nicotinamide given 1 h before, immediately after or 8 h after irradiation. Also, changes in the steepness of the underlying X-ray survival curve for the target skin clonogens, reflected by a change in the alpha/beta ratio, were investigated using the neutron top-up design. Underlying survival curves for oxygen +/- nicotinamide were obtained over the X-ray dose range 2.5 to 25 Gy, by administering single X-ray doses and following these with single top-up doses of d(4)-Be neutrons. Finally, in mouse kidney, recovery half-times (t1/2) were obtained by determining the time-dependent disappearance of X-ray damage using a split-dose design of two 6-Gy fractions separated by an interval which varied from 0 to 48 h and followed by two top-up doses from a neutron beam. No increase in alpha/beta for epidermal damage was seen with nicotinamide alone and, although sensitization was observed when the drug was given 1 h before irradiation, no postirradiation sensitization was detected. In kidney, there was no significant difference in the proportion of total repairable damage or in the half-life of recovery between treatments given with or without nicotinamide. Therefore, no decrease in normal tissue tolerance should be observed with the use of nicotinamide in clinical radiotherapy resulting either from reduced sparing with dose fractionation or from an increase in residual damage when shortening the interfraction interval. Finally, unless repair of radiation damage in normal tissues in vivo differs markedly from that of tumors, it is unlikely that the large sensitization seen in rodent tumors at 1.5 to 2 Gy per fraction, with carbogen and nicotinamide, can be attributed to nicotinamide acting as a repair inhibitor.
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Rojas A, Cruz S, Ponce-Monter H, Mata R. Smooth muscle relaxing compounds from Dodonaea viscosa. PLANTA MEDICA 1996; 62:154-159. [PMID: 8657750 DOI: 10.1055/s-2006-957840] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Bioassay-directed fractionation of the chloroform-methanol (1:1) extract of Dodonaea viscosa (L.) Jacq. (Sapindaceae) resulted in the isolation of four active spasmolytic principles: sakuranetin (1), 6-hydroxykaempferyl 3,7-dimethyl ether (2) hautrivaic acid (3), and ent-15, 16-epoxy-9 alpha H-labda-13(16)14-diene-3 beta, 8 alpha-diol (4). All the isolated compounds elicited a concentration-dependent inhibition of the spontaneous and electrically-induced contractions of guinea-pig ileum. Sakuranetin and the ent-labdane inhibited ileum contractions evoked by acetylcholine (Ach), histamine, and barium chloride. In addition, both substances were capable of relaxing contractions of rat uterus induced by Ca2+ in K(+)-depolarizing solution, displacing to the right the concentration-response curves to Ca2+. These results suggest that sakuranetin and ent-15,16-epoxy-9 alpha H-labda-13(16)14-diene-3 beta, 8 alpha-diol produce an interference with calcium metabolism in smooth muscle cells. The spasmolytic activity exhibited by the active principles from D. viscosa, provides the pharmacological basis for the traditional use of the plant as an antispasmodic agent.
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Rojas A, Vojnovic B, Johns H, Joiner MC, Martindale C, Fowler JF, Denekamp J. Radiosensitisation in normal tissues with oxygen, carbogen or nicotinamide: therapeutic gain comparisons for fractionated x-ray schedules. Radiother Oncol 1996; 39:53-64. [PMID: 8735494 DOI: 10.1016/0167-8140(95)01678-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
METHODS Radiosensitisation with oxygen, carbogen or nicotinamide alone and oxygen or carbogen combined with nicotinamide was compared in early and late responding normal tissues in rodents. X-ray treatments were delivered as single doses or fractionated schedules of 2 fractions in 1 day, 2, 12 and 36 fractions in an overall time of 12 days and 10 fractions in 5 or 12 days. Acute skin reactions, survival of intestinal crypts, breathing rate, reduction in the packed red-cell volume and clearance of 51Cr-EDTA were used as assays of epidermal, gut, lung and renal damage. RESULTS Relative to air-breathing mice, carbogen or oxygen produced a small, and not always significant, increase in sensitivity (enhancement ratios < or = 1.15) in gut, lung and kidneys; however, in skin a dose enhancement of 1.2-1.3 was observed. The effect of nicotinamide in air, carbogen or oxygen was studied only in lung and gut. The drug produced variable but generally significant increases in radiosensitisation ( < or = 1.26) in all three gases. Relative to treatments in air, enhancement ratios for nicotinamide alone were usually slightly higher than those observed when either carbogen or oxygen were administered without the drug. With all three modifiers (i.e. oxygen, carbogen, nicotinamide alone or for the drug-gas combinations) there was no significant change in the enhancement ratios observed as the number of radiation dose fractions was varied. CONCLUSIONS Comparisons with fractionated X-ray studies done previously in rodent tumours indicate that a therapeutic benefit, relative to lung, gut and renal damage, would be observed with oxygen or carbogen alone but not with nicotinamide alone. The greatest gain would be achieved with the combination of carbogen and nicotinamide, with which a benefit was observed even relative to epidermal damage. These results indicate that some decrease in normal tissue tolerance could be observed when using these modifiers in clinical radiotherapy and, although small, the appropriate dose reductions should be considered; caution should be exercised especially when carbogen and nicotinamide are used in conjunction with the more radical accelerated schedules.
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