Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 14 de 14
Filtrar
1.
Ann Oncol ; 30(8): 1298-1303, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31192355

RESUMO

BACKGROUND: This trial evaluated whether preoperative short-course radiotherapy and consolidation chemotherapy (CCT) were superior to chemoradiation in rectal cancers with clinical (c)T4 or fixed cT3. Previously, we reported early results showing no differences in the radical surgery rate (primary end point). In the short-course/CCT group, we observed lower acute toxicity of preoperative treatment and better overall survival (OS). We updated results to determine whether the benefit in OS was sustained and to evaluate late complications. PATIENTS AND METHODS: Patients with cT4 or fixed cT3 rectal cancer were randomized either to preoperative 5 × 5 Gy and three cycles of FOLFOX4 or to chemoradiation (50.4 Gy with bolus 5-Fu, leucovorin and oxaliplatin). RESULTS: Patients (N = 515) were eligible for analysis, 261 in the short-course/CCT group and 254 in the chemoradiation group. The median follow-up was 7.0 years. The difference in OS was insignificant [hazard ratio (HR) 0.90; 95% confidence interval (CI) 0.70-1.15; P = 0.38). However, the difference in early OS favouring short-course/CCT previously reported was observed again, being 9% at 3 years (95% CI 0.5% to 17%). This difference disappeared later; at 8 years OS was 49% in both groups. There was no difference in disease-free survival (HR 0.95; 95% CI 0.75-1.19; P = 0.65) at 8 years 43% versus 41% in the short-course/CCT group versus the chemoradiation group, respectively. The corresponding values for cumulative incidences of local failure and distant metastases did not differ and were HR = 1.08, 95% CI 0.70-1.23, P = 0.60, 35% versus 32% and HR = 1.10, 95% CI 0.68-1.23, P = 0.54, 36% versus 34%, respectively. The rate of late complications was similar (P = 0.66), grade 3+ being 11% versus 9% in the short-course/CCT group versus the chemoradiation group, respectively. CONCLUSION: The superiority of preoperative short-course/CCT over chemoradiation was not demonstrated. CLINICAL TRIAL NUMBER: The trial is registered as ClinicalTrials.gov number NCT00833131.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Fracionamento da Dose de Radiação , Terapia Neoadjuvante/métodos , Recidiva Local de Neoplasia/epidemiologia , Neoplasias Retais/terapia , Adolescente , Adulto , Idoso , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Quimiorradioterapia/efeitos adversos , Quimiorradioterapia/métodos , Quimioterapia de Consolidação/efeitos adversos , Quimioterapia de Consolidação/métodos , Intervalo Livre de Doença , Feminino , Fluoruracila/administração & dosagem , Fluoruracila/efeitos adversos , Seguimentos , Humanos , Incidência , Leucovorina/administração & dosagem , Leucovorina/efeitos adversos , Masculino , Pessoa de Meia-Idade , Terapia Neoadjuvante/efeitos adversos , Recidiva Local de Neoplasia/prevenção & controle , Compostos Organoplatínicos/administração & dosagem , Compostos Organoplatínicos/efeitos adversos , Polônia/epidemiologia , Protectomia , Neoplasias Retais/mortalidade , Neoplasias Retais/patologia , Reto/efeitos dos fármacos , Reto/patologia , Reto/efeitos da radiação , Reto/cirurgia , Fatores de Tempo , Adulto Jovem
3.
Eur J Surg Oncol ; 42(12): 1859-1865, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27546011

RESUMO

BACKGROUND: Whether there is any benefit derived from adding oxaliplatin to fluoropyrimidine-based preoperative chemoradiation is currently unknown in cases of advanced cT3 or cT4 tumours. Our aim was to evaluate this issue by analysing a randomized trial, which compared two schedules of preoperative treatment (chemoradiation vs. 5 × 5 Gy with 3 cycles of consolidation chemotherapy) for cT4 or fixed cT3 rectal cancer. PATIENTS AND METHODS: Delivery of oxaliplatin was mandatory to the first part of the study. For the second part, its delivery in both treatment-assigned groups was left to the discretion of the local investigator. We analysed a subgroup of 272 patients (136 in the oxaliplatin group and 136 in the fluorouracil-only group) from institutions that had omitted oxaliplatin in the second part of the study. RESULTS: Circumferential resection margin negative (CRM-) status rate was 68% in the oxaliplatin group and 70% in the fluorouracil-only group, p = 0.72. The pathological complete response rate (pCR) was correspondingly 14% vs. 7%, p = 0.10. Following multivariable analysis, when comparing the CRM- status in the oxaliplatin group to the fluorouracil-only group, the odds ratio was 0.79 (95 CI 0.35-1.74), p = 0.54; there being no interaction between concomitant chemoradiation and 5 × 5 Gy with consolidation chemotherapy; pinteraction = 0.073. For pCR, the corresponding results were 0.47 (95 CI 0.19-1.16), p = 0.10, pinteraction = 0.84. CONCLUSION: No benefit was found of adding oxaliplatin in terms of CRM nor pCR rates for either concomitant or sequential settings in preoperative radiochemotherapy for very advanced rectal cancer.


Assuntos
Adenocarcinoma/terapia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Quimiorradioterapia , Procedimentos Cirúrgicos do Sistema Digestório , Terapia Neoadjuvante , Neoplasias Retais/terapia , Adenocarcinoma/patologia , Idoso , Feminino , Fluoruracila/administração & dosagem , Fluoruracila/uso terapêutico , Humanos , Leucovorina/administração & dosagem , Leucovorina/uso terapêutico , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Compostos Organoplatínicos/administração & dosagem , Compostos Organoplatínicos/uso terapêutico , Oxaliplatina , Estudos Prospectivos , Neoplasias Retais/patologia , Resultado do Tratamento
4.
Ann Oncol ; 27(5): 834-42, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26884592

RESUMO

BACKGROUND: Improvements in local control are required when using preoperative chemoradiation for cT4 or advanced cT3 rectal cancer. There is therefore a need to explore more effective schedules. PATIENTS AND METHODS: Patients with fixed cT3 or cT4 cancer were randomized either to 5 × 5 Gy and three cycles of FOLFOX4 (group A) or to 50.4 Gy in 28 fractions combined with two 5-day cycles of bolus 5-Fu 325 mg/m(2)/day and leucovorin 20 mg/m(2)/day during the first and fifth week of irradiation along with five infusions of oxaliplatin 50 mg/m(2) once weekly (group B). The protocol was amended in 2012 to allow oxaliplatin to be then foregone in both groups. RESULTS: Of 541 entered patients, 515 were eligible for analysis; 261 in group A and 254 in group B. Preoperative treatment acute toxicity was lower in group A than group B, P = 0.006; any toxicity being, respectively, 75% versus 83%, grade III-IV 23% versus 21% and toxic deaths 1% versus 3%. R0 resection rates (primary end point) and pathological complete response rates in groups A and B were, respectively, 77% versus 71%, P = 0.07, and 16% versus 12%, P = 0.17. The median follow-up was 35 months. At 3 years, the rates of overall survival and disease-free survival in groups A and B were, respectively, 73% versus 65%, P = 0.046, and 53% versus 52%, P = 0.85, together with the cumulative incidence of local failure and distant metastases being, respectively, 22% versus 21%, P = 0.82, and 30% versus 27%, P = 0.26. Postoperative and late complications rates in group A and group B were, respectively, 29% versus 25%, P = 0.18, and 20% versus 22%, P = 0.54. CONCLUSIONS: No differences were observed in local efficacy between 5 × 5 Gy with consolidation chemotherapy and long-course chemoradiation. Nevertheless, an improved overall survival and lower acute toxicity favours the 5 × 5 Gy schedule with consolidation chemotherapy. CLINICAL TRIAL NUMBER: The trial is registered as ClinicalTrials.gov number NCT00833131.


Assuntos
Quimiorradioterapia , Compostos Organoplatínicos/administração & dosagem , Neoplasias Retais/tratamento farmacológico , Neoplasias Retais/radioterapia , Idoso , Terapia Combinada , Quimioterapia de Consolidação , Intervalo Livre de Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Oxaliplatina , Cuidados Pré-Operatórios , Dosagem Radioterapêutica , Neoplasias Retais/patologia , Neoplasias Retais/cirurgia
5.
Eur J Surg Oncol ; 42(2): 288-96, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26506863

RESUMO

BACKGROUND: During an ongoing phase II observational study on watch and wait policy in rectal cancer, a substantial number of patients presented residual lesion after radiotherapy with a clinical benign appearance. This article aims to discuss the clinical significance of such findings. MATERIALS AND METHODS: Main entry criteria were age ≥70 years and small tumour (≤5 cm and ≤60% of circumferential involvement) located in the low rectum. Patients received chemoradiation (50 Gy, 2 Gy per fraction concomitantly with a 5-Fu bolus and leucovorin) or 5 × 5 Gy if considered unfit for chemotherapy. Patients with clinical complete response (cCR) were observed. Those with persistent tumours underwent transanal endoscopic microsurgery [TEM] if the baseline tumour was ≤3 cm and cN0 or total mesorectal excision. RESULTS: The watch and wait procedure was used in 11 out of the total 35 patients (31%) with a cCR; 17 patients (49%) with residual tumours that appeared clinically malignant were referred for TEM or abdominal surgery. In the remaining seven (20%), the residual tumour clinically appeared benign. Of these, there were two invasive cancers, four high-grade dysplasias and one low-grade dysplasia. The five patients with dysplasia, underwent local lesion resection without recurrence within a median of 11 months follow-up. CONCLUSIONS: The majority of lesions that appeared clinically benign after radio(chemo)therapy were also benign on pathological examination. Thus, local excision of such lesions should be considered.


Assuntos
Adenocarcinoma/patologia , Adenocarcinoma/terapia , Quimiorradioterapia , Neoplasias Retais/patologia , Neoplasias Retais/terapia , Conduta Expectante , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Fracionamento da Dose de Radiação , Feminino , Fluoruracila/administração & dosagem , Humanos , Leucovorina/administração & dosagem , Masculino , Neoplasia Residual , Tratamentos com Preservação do Órgão , Microcirurgia Endoscópica Transanal , Carga Tumoral
6.
Tech Coloproctol ; 18(10): 921-8, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24993838

RESUMO

BACKGROUND: Despite the findings of several randomized clinical studies, the role of gentamicin collagen implant (GCI) in rectal cancer surgery is unclear. Local pelvic application of GCI following preoperative radiotherapy and total mesorectal excision (TME) was evaluated to determine the risk of surgical site infections (SSI). METHODS: In this single-center trial, 176 patients with rectal cancer after preoperative, short-term radiotherapy (5 × 5 Gy) were randomized either to the study group in which GCI was used or in the control group without GCI. Prior to surgery and intraoperatively five patients were excluded from the study. The remaining 171 patients were analyzed; 86 were in the study group and 85 in the control group. RESULTS: There were no statistically significant differences in the overall rate of early postoperative complications between the study and control group: 25.6 and 34.1 % respectively; p = 0.245, relative risk (RR) 0.750 [95 % confidence interval (CI) 0.471-1.195]. The reoperation rate was similar in both groups: 12.8 versus 9.4 %; p = 0.628; RR 1.359; (95 % CI 0.575-3.212). The total rate of SSI and organ space SSI were 22.2 and 15.8 % without differences between the study and control group. In patients without anastomotic leakage, the risk of organ space SSI was significantly reduced in patients who received GCI: 2.6 versus 13.0 %; p = 0.018. CONCLUSIONS: Application of GCI in the pelvic cavity after short-term preoperative radiotherapy and TME may reduce the risk of organ space SSI but only in the absence of anastomotic leakage.


Assuntos
Antibacterianos/uso terapêutico , Gentamicinas/uso terapêutico , Neoplasias Retais/cirurgia , Infecção da Ferida Cirúrgica/prevenção & controle , Adulto , Idoso , Idoso de 80 Anos ou mais , Fístula Anastomótica/tratamento farmacológico , Fístula Anastomótica/prevenção & controle , Antibacterianos/administração & dosagem , Colágeno/administração & dosagem , Terapia Combinada , Procedimentos Cirúrgicos do Sistema Digestório/efeitos adversos , Procedimentos Cirúrgicos do Sistema Digestório/métodos , Feminino , Gentamicinas/administração & dosagem , Humanos , Masculino , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/cirurgia , Neoplasias Retais/radioterapia , Fatores de Risco , Infecção da Ferida Cirúrgica/complicações , Infecção da Ferida Cirúrgica/tratamento farmacológico
7.
Eur J Surg Oncol ; 40(6): 723-30, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24332947

RESUMO

AIMS: Local excision with preoperative radiotherapy may be considered as alternative management to abdominal surgery alone for small cT2-3N0 tumours. However, little is known about anorectal and sexual functions after local excision with preoperative radiotherapy. Evaluation of this issue was a secondary aim of our previously published prospective multicentre study. METHODS: Functional evaluation was based on a questionnaire completed by 44 of 64 eligible disease-free patients treated with preoperative radiotherapy and local excision. Additionally, ex post, these results were confronted with those recorded retrospectively in the control group treated with anterior resection alone (N = 38). RESULTS: In the preoperative radiotherapy and local excision group, the median number of bowel movements was two per day, incontinence of flatus occurred in 51% of patients, incontinence of loose stool in 46%, clustering of stools in 59%, and urgency in 49%; these symptoms occurred often or very often in 11%-21% of patients. Thirty-eight per cent of patients claimed that their quality of life was affected by anorectal dysfunction. Nineteen per cent of men and 20% of women claimed that the treatment negatively influenced their sexual life. The anorectal functions in the preoperative radiotherapy and local excision group were not much different from that observed in the anterior resection alone group. CONCLUSIONS: Our study suggests that anorectal functions after preoperative radiotherapy and local excision may be worse than expected and not much different from that recorded after anterior resection alone. It is possible that radiotherapy compromises the functional effects achieved by local excision.


Assuntos
Canal Anal/fisiopatologia , Neoplasias Retais/radioterapia , Neoplasias Retais/cirurgia , Reto/fisiopatologia , Comportamento Sexual , Adulto , Idoso , Idoso de 80 Anos ou mais , Terapia Combinada , Defecação/fisiologia , Incontinência Fecal/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Terapia Neoadjuvante , Estadiamento de Neoplasias , Complicações Pós-Operatórias/epidemiologia , Recuperação de Função Fisiológica/fisiologia , Neoplasias Retais/patologia , Estudos Retrospectivos , Inquéritos e Questionários , Resultado do Tratamento
8.
Ann Oncol ; 24(11): 2829-34, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24013512

RESUMO

BACKGROUND: In stage IV rectal cancer, palliative surgery is often carried out upfront. This study investigated whether the surgery can be avoided. PATIENTS AND METHODS: Forty patients with symptomatic primary rectal adenocarcinoma and synchronous distant metastases deemed to be unresectable received 5 × 5 Gy irradiation and then oxaliplatin-based chemotherapy. Before treatment, 38% of patients had a near-obstructing lesion. The palliative effect was evaluated by questionnaires completed by the patients. RESULTS: The median follow-up for living patients was 26 months (range 19-34). The median overall survival was 11.5 months. Eight patients (20%) required surgery during the course of their disease: seven patients required stoma creation and one had local excision. Thirty percent of patients had a complete resolution of pelvic symptoms during the whole course of the disease, and 35% had significant improvement. In the subgroup with a near-obstructing lesion, 23% of patients required stoma creation. In all patients, the probability of requiring palliative surgery at 2 years was 17.5% [95% confidence interval (CI) 13% to 22%), and the probability of sustained good palliative effect after radiotherapy and chemotherapy was 67% (95% CI 58% to 76%). CONCLUSION: Short-course radiotherapy and chemotherapy allowed most patients to avoid surgery, even those with a near-obstructing lesion. CLINICALTRIALS: The trial is registered with ClinicalTrials.gov: number NCT01157806.


Assuntos
Cuidados Paliativos , Neoplasias Retais/tratamento farmacológico , Neoplasias Retais/radioterapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Terapia Combinada , Intervalo Livre de Doença , Feminino , Fluoruracila/administração & dosagem , Fluoruracila/efeitos adversos , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Metástase Neoplásica/terapia , Estadiamento de Neoplasias , Compostos Organoplatínicos/administração & dosagem , Oxaliplatina , Neoplasias Retais/cirurgia , Análise de Sobrevida , Resultado do Tratamento
9.
Clin Exp Dermatol ; 34(3): 380-4, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19175785

RESUMO

BACKGROUND: It has been suggested that topically applied nicotinamide and its metabolite N-methylnicotinamide (NMN(+)) might be useful agents for treatment of dermatological disorders such as acne vulgaris and rosacea. AIM: This study aimed to find out if the mechanism of these therapeutic effects depends on their vascular effects, by investigating if nicotinamide and NMN(+) are able to influence vascular permeability of the vessels in the skin on the back of Wistar rats. METHODS AND RESULTS: A dose-dependent increase in vascular permeability was seen in rats treated intradermally with nicotinamide and NMN(+). Interestingly, a significantly stronger effect of NMN(+) compared with nicotinamide was evident. Increased vascular permeability in rats treated with 0.5% NMN(+) ointment was seen. Moreover, indomethacin, a cyclo-oxygenase 1 and 2 inhibitor and N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide (NO) synthase inhibitor, reduced the observed effects of nicotinamide and NMN(+). CONCLUSIONS: This study provides direct in vivo evidence that nicotinamide and its metabolite NMN(+) increase skin vascular permeability in rats by a mechanism that may involve NO and prostaglandins.


Assuntos
Permeabilidade Capilar/efeitos dos fármacos , Niacinamida/análogos & derivados , Niacinamida/farmacologia , Pele/irrigação sanguínea , Complexo Vitamínico B/farmacologia , Animais , Permeabilidade Capilar/fisiologia , Relação Dose-Resposta a Droga , Injeções Intradérmicas , Masculino , Óxido Nítrico/fisiologia , Prostaglandinas/fisiologia , Ratos , Ratos Wistar , Pele/efeitos dos fármacos
10.
J Physiol Pharmacol ; 58(3): 515-27, 2007 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-17928647

RESUMO

There are few findings indicating that nicotinamide may potentially influence intravascular thrombosis. Interestingly, N-methylnicotinamide, one of the metabolites of nicotinamide - could be more potent than its parent compound. In the present study we have investigated the influence of N-methylnicotinamide on arterial thrombosis in normotensive and renovascular hypertensive rats. The contribution of platelets, coagulation and fibrinolytic systems in the mode of N-methylnicotinamide action was also determined. Furthermore, we examined the role of nitric oxide/prostacyclin in the mechanisms of N-methylnicotinamide action. N-methylnicotinamide, but not nicotinamide, administered intravenously into renovascular hypertensive rats developing electrically induced arterial thrombosis caused dose-dependent decrease of thrombus weight, collagen-induced platelet aggregation and plasma antigen/activity of plasminogen activator inhibitor - 1, without changing of occlusion time, routine coagulation parameters and plasma activity of tissue plasminogen activator. Indomethacin - an inhibitor of prostacyclin synthesis, completely abolished the antithrombotic and antiplatelet effect of N-methylnicotinamide, and the plasma level of 6-keto-PGF(1alpha) , prostacyclin metabolite, increased simultaneously with the inhibition of thrombus formation. Our study shows that N-methylnicotinamide via production/release of prostacyclin inhibits arterial thrombosis development. The antithrombotic effect of N-methylnicotinamide is accompanied by platelet inhibition and enhanced fibrinolysis, due to the decrease production of plasminogen activator inhibitor - 1.


Assuntos
Hipertensão Renal/complicações , Niacinamida/análogos & derivados , Trombose/prevenção & controle , 6-Cetoprostaglandina F1 alfa/metabolismo , Animais , Velocidade do Fluxo Sanguíneo/efeitos dos fármacos , Pressão Sanguínea/efeitos dos fármacos , Artérias Carótidas/efeitos dos fármacos , Artérias Carótidas/fisiopatologia , Colágeno/efeitos adversos , Colágeno/antagonistas & inibidores , Relação Dose-Resposta a Droga , Epoprostenol/antagonistas & inibidores , Fibrinólise/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Hipertensão Renal/fisiopatologia , Indometacina/farmacologia , Injeções Intravenosas , Masculino , NG-Nitroarginina Metil Éster/farmacologia , Niacinamida/administração & dosagem , Niacinamida/farmacologia , Óxido Nítrico Sintase/antagonistas & inibidores , Agregação Plaquetária/efeitos dos fármacos , Inibidores da Agregação Plaquetária/farmacologia , Ratos , Ratos Wistar , Trombose/complicações , Trombose/metabolismo
11.
Biotech Histochem ; 80(3-4): 117-21, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16298896

RESUMO

Typical preparation of seed samples for infrared (IR) microspectroscopy involves imbibition of the seed for varying time periods followed by cryosectioning. Imbibition, however, may initiate germination even at 4 degrees C with associated changes in the chemistry of the sample. We have found that it is possible to section seeds that are sufficiently hard, such as soybeans, on a standard laboratory microtome without imbibition. The use of dry sectioning of unimbibed seeds is reported here, as well as a comparison of different mounting media and modes of analysis. Glycerol, Tissue-Tek, and ethanol were used as mounting media, and the quality of the resulting spectra was assessed. Ethanol was the preferred mountant, because it dried quickly with no residue and thus did not interfere with the spectrum of interest. Analysis in transmission mode using barium fluoride windows to hold the samples was compared with transmission-reflection analysis with sections mounted on special infrared-reflecting slides. The two modes of analysis performed well in different regions of the spectrum. The mode of analysis (transmission vs. transmission-reflection) should be based on the components of greatest interest in the sample.


Assuntos
Glycine max/química , Microtomia/métodos , Proteínas de Plantas/análise , Sementes/química , Manejo de Espécimes/métodos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Dessecação/métodos
12.
J Agric Food Chem ; 49(8): 3559-66, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11513628

RESUMO

The concentration of ferulic acid (FA), the major phenolic acid in the wheat kernel, was found to differ significantly in the mature grain of six wheat cultivars known to have a range of tolerance to the orange wheat blossom midge (Sitodiplosis mosellana). Differences in FA content were correlated with floret infestation level of the cultivars. The wheat cultivars ranked similarly in FA content at the four locations where they were tested, despite a significant effect of environment. Ferulic acid was synthesized mainly during the early stages of grain filling but at different rates among cultivars. Ferulic acid was concentrated primarily in the shorts and bran fractions in an insoluble-bound form. A high correlation was obtained between FA contents as determined by GLC, fluorometry, UV, and colorimetry. The colorimetric procedure was modified as a qualitative, simple, and rapid test for identifying midge-resistant wheat and evaluated in several field trials. The method should provide a rapid tool in the preliminary screening of experimental lines in the development of midge-resistant wheat cultivars.


Assuntos
Ácidos Cumáricos/farmacologia , Dípteros/efeitos dos fármacos , Triticum/química , Animais , Colorimetria/métodos , Resistência a Medicamentos
13.
Cell Mol Biol (Noisy-le-grand) ; 44(1): 145-68, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9551647

RESUMO

Routine use of 6 microm or 12 microm apertures with synchrotron microspectroscopy provide good spectra without excessive co-addition of scans. 100% mapping by stepping in pixel sized increments reveals chemical heterogeneity within cellular dimensions. The brightness of the synchrotron source and the absence of thermal noise compared to a conventional thermal (globar) source yields favorable signal-to-noise operation. The nondivergent characteristics of the source result in minimal loss of radiation at the aperture, hence, spatial resolution approaches the diffraction limit. Details of cellular dimensions are then localized within any maps produced and individual spectra obtained from adjacent pixels clearly shows the striking difference in chemistry even within a microscopic vicinity. In this report the mapping of plant tissue with the synchrotron is contrasted to previous lower spatial resolution mapping experiments done with the globar on similar materials using interpolation between separated sampling spots and larger apertures.


Assuntos
Plantas/ultraestrutura , Espectrofotometria Infravermelho/métodos , Absorção , Avena , Glucanos/análise , Microtomia , Raízes de Plantas/ultraestrutura , Poaceae , Síncrotrons , Triticum/ultraestrutura , Zea mays/ultraestrutura
14.
Genetics ; 119(4): 981-90, 1988 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-17246441

RESUMO

Wild barley (Hordeum spontaneum K.) and indigenous primitive varieties of cultivated barley (Hordeum vulgare L.), collected from 43 locations in four eastern Mediterranean countries, Jordan, Syria, Turkey and Greece, were electrophoretically assayed for genetic diversity at 16 isozyme loci. Contrary to a common impression, cultivated barley populations were found to maintain a level of diversity similar to that in its wild progenitor species. Apportionment of overall diversity in the region showed that in cultivated barley within-populations diversity was of higher magnitude than the between-populations component. Neighboring populations of wild and cultivated barleys showed high degree of genetic identity. Groups of 3 or 4 isozyme loci were analyzed to detect associations among loci. Multilocus associations of varying order were detected for all three groups chosen for the analysis. Some of the association terms differed between the two species in the region. Although there was no clear evidence for decrease in diversity attributable to the domestication of barley in the region, there was an indication of different multilocus organizations in the two closely related species.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...