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1.
Naturwissenschaften ; 108(4): 25, 2021 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-34091791

RESUMO

Deception has evolved in a range of taxa. When deception imposes costs, yet persists over generations, exploited species typically have traits to help them bear or minimise costs. The sexually deceptive orchids, Cryptostylis spp., are pollinated by tricking male haplodiploid wasps (Lissopimpla excelsa) into mating with flowers, which offer no reward and often elicit sperm wastage. We hypothesise that by attracting haplodiploid species, orchids have a pollinator ideally suited to withstand the costs of sexual deception-and a selective advantage compared to other orchids. Haplodiploid females can reproduce with or without sperm-albeit when spermless, females can only have sons. Through orchid deception and sperm wastage, deceived haplodiploid populations could become male biased, providing enough males to share between orchids and females. In this way, pollinator populations can persist despite high densities of sexually deceptive orchids. Here, we aim to broadly test this prediction using museum and digital records of the pollinator, L. excelsa, from sites with or without orchids. For robustness, we also analyse the sex ratio of a sister ichneumonid species that occurs in the same areas but is not deceived by orchids. We found that at sites with orchids, L. excelsa was significantly more male biased than at sites without orchids and significantly more male biased than the sister ichneumonid. This survey is the first to test the population-level effects of sexually deceptive orchids on their pollinator. It supports our prediction that orchid deception can drive male-biased sex ratios in exploited pollinators.


Assuntos
Flores/anatomia & histologia , Flores/fisiologia , Orchidaceae/anatomia & histologia , Orchidaceae/fisiologia , Polinização/fisiologia , Animais , Feminino , Masculino , Museus , Comportamento Sexual Animal/fisiologia
2.
J Evol Biol ; 30(12): 2146-2155, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28902470

RESUMO

Many hypotheses explaining the evolution and maintenance of sexual cannibalism incorporate the nutritional aspect of the consumption of males. Most studies have focused on a fecundity advantage through consumption of a male; however, recent studies have raised the intriguing possibility that consumption of a male may also affect offspring quality. In particular, recent studies suggest prolonged survival for offspring from sexually cannibalistic females. Here, we measured the protein and lipid content of males compared to insect prey (crickets), quantified female nutrient intake of both prey types and finally assessed how sexual cannibalism affects female fecundity and spiderling quality in the orb-web spider Larinioides sclopetarius. We found no evidence that sexual cannibalism increased fecundity when compared to a female control group fed a cricket. Contrary to previous studies, spiderlings from females fed a male showed reduced survival under food deprivation compared to spiderlings from the control group. Offspring from females fed a male also tended to begin web construction sooner. The low lipid content of males compared to crickets may have reduced offspring survival duration. Whether additional proteins obtained through consumption of a male translate to enhanced silk production in offspring requires further investigation.


Assuntos
Canibalismo , Comportamento Sexual Animal , Aranhas/fisiologia , Animais , Evolução Biológica , Feminino , Fertilidade , Masculino , Valor Nutritivo
3.
J Clin Pharm Ther ; 42(2): 228-233, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28111765

RESUMO

WHAT IS KNOWN AND OBJECTIVE: There are few studies examining both drug-drug and drug-disease interactions in older adults. Therefore, the objective of this study was to describe the prevalence of potential drug-drug and drug-disease interactions and associated factors in community-dwelling older adults. METHODS: This cross-sectional study included 3055 adults aged 70-79 without mobility limitations at their baseline visit in the Health Aging and Body Composition Study conducted in the communities of Pittsburgh PA and Memphis TN, USA. The outcome factors were potential drug-drug and drug-disease interactions as per the application of explicit criteria drawn from a number of sources to self-reported prescription and non-prescription medication use. RESULTS: Over one-third of participants had at least one type of interaction. Approximately one quarter (25·1%) had evidence of had one or more drug-drug interactions. Nearly 10·7% of the participants had a drug-drug interaction that involved a non-prescription medication. % The most common drug-drug interaction was non-steroidal anti-inflammatory drugs (NSAIDs) affecting antihypertensives. Additionally, 16·0% had a potential drug-disease interaction with 3·7% participants having one involving non-prescription medications. The most common drug-disease interaction was aspirin/NSAID use in those with history of peptic ulcer disease without gastroprotection. Over one-third (34·0%) had at least one type of drug interaction. Each prescription medication increased the odds of having at least one type of drug interaction by 35-40% [drug-drug interaction adjusted odds ratio (AOR) = 1·35, 95% confidence interval (CI) = 1·27-1·42; drug-disease interaction AOR = 1·30; CI = 1·21-1·40; and both AOR = 1·45; CI = 1·34-1·57]. A prior hospitalization increased the odds of having at least one type of drug interaction by 49-84% compared with those not hospitalized (drug-drug interaction AOR = 1·49, 95% CI = 1·11-2·01; drug-disease interaction AOR = 1·69, CI = 1·15-2·49; and both AOR = 1·84, CI = 1·20-2·84). WHAT IS NEW AND CONCLUSION: Drug interactions are common among community-dwelling older adults and are associated with the number of medications and hospitalization in the previous year. Longitudinal studies are needed to evaluate the impact of drug interactions on health-related outcomes.


Assuntos
Interações Medicamentosas , Idoso , Anti-Inflamatórios não Esteroides/efeitos adversos , Estudos Transversais , Feminino , Humanos , Masculino
4.
Water Sci Technol ; 73(3): 654-61, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26877050

RESUMO

A total maximum daily load (TMDL) for oxygen demanding substances is being implemented in the San Joaquin River (SJR) in California (USA) due to frequently occurring low dissolved oxygen conditions. The SJR is a eutrophic river, heavily impacted by agriculture. A mass balance was developed to identify the sources of oxygen-demanding substances and nutrients to the river with the objective of providing a scientific basis for management actions needed to meet TMDL requirements. Data were collected for flow and water quality and mass loads calculated for sites within the main stem of the SJR, river inputs (tributaries), and diversions in the study area. Using a quadrant analysis, tributary flows and loads are ranked to identify targets for water quality improvement efforts. Additionally, all mass loads were summed (inputs minus diversions) and compared with observed loads at the downstream limit of the study area. The mass balance analysis identifies major contributors of mass loads and mass balance closure is assessed for each constituent. These analysis methods inform the TMDL process which includes a load allocation, and is useful for determining locations for implementation of improvement projects needed to improve the health of the river.


Assuntos
Monitoramento Ambiental/métodos , Oxigênio/análise , Rios/química , Eliminação de Resíduos Líquidos/métodos , California
5.
Phys Med Biol ; 60(24): 9203-13, 2015 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-26576672

RESUMO

This work uses Monte Carlo radiation transport simulation to assess the potential benefits of gold nanoparticles (AuNP) in the treatment of neovascular age-related macular degeneration with stereotactic radiosurgery. Clinically, a 100 kVp x-ray beam of 4 mm diameter is aimed at the macula to deliver an ablative dose in a single fraction. In the transport model, AuNP accumulated at the bottom of the macula are targeted with a source representative of the clinical beam in order to provide enhanced dose to the diseased macular endothelial cells. It is observed that, because of the AuNP, the dose to the endothelial cells can be significantly enhanced, allowing for greater sparing of optic nerve, retina and other neighboring healthy tissue. For 20 nm diameter AuNP concentration of 32 mg g(-1), which has been shown to be achievable in vivo, a dose enhancement ratio (DER) of 1.97 was found to be possible, which could potentially be increased through appropriate optimization of beam quality and/or AuNP targeting. A significant enhancement in dose is seen in the vicinity of the AuNP layer within 30 µm, peaked at the AuNP-tissue interface. Different angular tilting of the 4 mm beam results in a similar enhancement. The DER inside and in the penumbra of the 4 mm irradiation-field are almost the same while the actual delivered dose is more than one order of magnitude lower outside the field leading to normal tissue sparing. The prescribed dose to macular endothelial cells can be delivered using almost half of the radiation allowing reduction of dose to the neighboring organs such as retina/optic nerve by 49% when compared to a treatment without AuNP.


Assuntos
Endotélio Vascular/patologia , Ouro/química , Degeneração Macular/cirurgia , Nanopartículas Metálicas/química , Método de Monte Carlo , Neovascularização Patológica , Radiocirurgia/métodos , Endotélio Vascular/efeitos da radiação , Olho/fisiopatologia , Olho/efeitos da radiação , Humanos , Degeneração Macular/patologia , Raios X
6.
Vet Rec ; 172(20): 526, 2013 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-23559425

RESUMO

Coelioscopic orchiectomy was performed in 27 male turtles (25 juvenile to adult red-eared sliders (Trachemys scripta elegans), one adult eastern painted turtle (Chrysems picta picta), and one juvenile male yellow-spotted Amazon River turtle (Podocnemis unifilis)). Orchiectomy was conducted under coelioscopic visualisation using ligation and transection of the mesorchium, or transection of the mesorchium with monopolar radiosurgical scissors. In 22 cases, bilateral orchiectomy was performed through a single incision; five turtles required bilateral incisions. All turtles recovered from anaesthesia. Nine turtles died within one year of surgery from conditions believed to be unrelated to surgery. One turtle was lost to follow-up. Seventeen turtles remain clinically healthy one to three years postoperatively. Coelioscopic orchiectomy provides a minimally invasive method for sterilisation of male chelonians and provides excellent visualisation during surgery. This technique is a useful model for the development of additional minimally invasive surgical techniques for chelonians.


Assuntos
Laparoscopia/veterinária , Orquiectomia/veterinária , Complicações Pós-Operatórias/veterinária , Tartarugas/cirurgia , Animais , Laparoscopia/métodos , Masculino , Orquiectomia/instrumentação , Orquiectomia/métodos , Orquiectomia/mortalidade , Complicações Pós-Operatórias/epidemiologia , Resultado do Tratamento
7.
Med Phys ; 39(6Part17): 3815, 2012 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28517457

RESUMO

PURPOSE: This work determines how variations in eye size will influence the radiation absorbed dose delivered to non-targeted tissues within the eye during stereotactic radiosurgery of age-related macular degeneration (AMD) using the IRay™ treatment. METHODS: Stylized models of the eye were created with axial lengths of 20, 22, 24, 26, and 28mm. Each model was based upon the reference eye model from NCRP Report 130 and then scaled appropriately for each axial length. Models were incorporated with MCNPX radiation transport code in order to simulate the three beam IRay™ delivery system. Simulation results were assessed for both the mean absorbed dose and dose-volume histograms (DVH) for both target (macula) and non- targeted eye tissues, including the lens, retina, central retinal artery, and optic nerve. RESULTS: For each of the three beams, an average dose of 8Gy was delivered to the macula resulting in a total average dose of 24Gy for each eye model. The lens of the eye received a total average dose ranging from 146 to 189mGy, with the larger doses occurring in the smaller eye models since the beams traverse through the sciera closer to the limbus. The distal tip (1.5mm) of the central retinal artery received a total average dose ranging from 499 to 567mGy, with the larger doses occurring in the larger eye models due to increased scatter resulting from longer tissue path length to the nominal target. The optic nerve received a total average dose ranging from 207 to 225mGy, with the larger doses occurring in the smaller eye models. CONCLUSIONS: The small variation in dose to the lens, central retinal artery, and optic nerve suggests that eye size does not significantly affect radiation dose to non-targeted eye tissues. This work was sponsored by Oraya Therapeutics.

8.
Ir J Med Sci ; 180(4): 917-9, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21779941

RESUMO

BACKGROUND: Sleep paralysis (SP) is characterised by an inability to move voluntarily for a period on going to sleep or on waking. It is also associated with hallucinations, and often with fear. This study seeks to explore the experience of SP in an Irish university sample. METHODS: A cross-sectional survey design was employed, with a validated scale for the assessment of SP being distributed to 2,500 students. A total of 418 responded, of whom 83 reported having experienced SP. RESULTS: The most commonly reported and most intense hallucinations were falling, sensed presence, visual hallucination, pressure on the body and belief might be dying. Fear was also commonly experienced. Bivariate analyses showed an association between fear and several hallucination types. CONCLUSION: SP in university students often includes experience of hallucinations. These, in turn, are associated with frequent and intense fear.


Assuntos
Medo/psicologia , Alucinações/psicologia , Paralisia do Sono/psicologia , Estudantes/psicologia , Adolescente , Adulto , Estudos Transversais , Coleta de Dados , Feminino , Humanos , Irlanda , Masculino , Adulto Jovem
12.
Br J Anaesth ; 104(5): 619-27, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20354007

RESUMO

BACKGROUND: Epidural catheter insertion for labour analgesia is an invasive procedure with potential serious complications, often performed by a sleep-deprived clinician. The aim of this study was to examine the effects of sleep deprivation on physicians of variable levels of experience performing this procedural skill in the clinical setting. METHODS: After institutional review board approval, anaesthetists of three levels of experience were recruited: novice residents (<30 epidurals, n=9), experienced residents (>100 epidurals, n=8), and attending anaesthetists (>500 epidurals, n=12). All participants were measured twice, rested and sleep deprived in a random order while performing a labour epidural for analgesia. Our primary outcome measures were scores achieved on the Imperial College Surgical Assessment Device (ICSAD) (measuring path length, number of movements, and time), task-specific checklist (CL), and global rating scale (GRS). Sleep deprivation was documented by the ActiGraph and Epworth sleepiness scale. RESULTS: Subjects were adequately sleep deprived for their sleep deprivation observation. Data were analysed with a two-way mixed design analysis of variance. No significant difference in the effect of sleep deprivation on performance was detected between the groups on the ICSAD measures of movement (P=0.86), path length (P=0.79), and time (P=0.80), or for the CL (P=0.65), and GRS (P=0.86). CONCLUSIONS: The performance of this procedural skill in a clinical setting does not seem to be affected by sleep deprivation irrespective of the level of experience.


Assuntos
Analgesia Epidural/normas , Analgesia Obstétrica/normas , Anestesiologia , Competência Clínica , Inabilitação do Médico , Privação do Sono/psicologia , Analgesia Obstétrica/métodos , Feminino , Humanos , Masculino , Corpo Clínico Hospitalar/psicologia , Corpo Clínico Hospitalar/normas , Ontário , Gravidez , Desempenho Psicomotor , Tolerância ao Trabalho Programado/psicologia
13.
Qual Saf Health Care ; 15(6): 400-4, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17142586

RESUMO

OBJECTIVE: To assess patient safety culture (PSC) in the nursing home setting, to determine whether nursing home professionals differ in their PSC ratings, and to compare PSC scores of nursing homes with those of hospitals. METHODS: The Hospital Survey on Patient Safety Culture was modified for use in nursing homes (PSC-NH) and distributed to 151 professionals in four non-profit nursing homes. Mean scores on each PSC-NH dimension were compared across professions (doctors, pharmacists, advanced practitioners and nurses) and with published benchmark scores from 21 hospitals. RESULTS: Response rates were 68.9% overall and 52-100% for different professions. Most respondents (76%) were women and had worked in nursing homes for an average of 9.8 years, and at their current facility for 5.4 years. Professions agreed on 11 of 12 dimensions of the survey and differed significantly (p<0.05) only in ratings for one PSC dimension (attitudes about staffing issues), where nurses and pharmacists believed that they had enough employees to handle the workload. Nursing homes scored significantly lower (ie, worse) than hospitals (p<0.05) in five PSC dimensions (non-punitive response to error, teamwork within units, communication openness, feedback and communication about error, and organisational learning). CONCLUSIONS: Professionals in nursing homes generally agree about safety characteristics of their facilities, and the PSC in nursing homes is significantly lower than that in hospitals. PSC assessment may be helpful in fostering comparisons across nursing home settings and professions, and identifying targets for interventions to improve patient safety.


Assuntos
Atitude do Pessoal de Saúde , Pesquisas sobre Atenção à Saúde , Casas de Saúde/normas , Cultura Organizacional , Gestão da Segurança , Adulto , Pessoal Técnico de Saúde/psicologia , Benchmarking , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Casas de Saúde/organização & administração , Recursos Humanos de Enfermagem/psicologia , Organizações sem Fins Lucrativos/normas , Pennsylvania , Farmacêuticos/psicologia , Médicos/psicologia
14.
Epilepsy Res ; 68 Suppl 1: S49-63, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16207524

RESUMO

In this article, epidemiological and clinical aspects related to the use of antiepileptic drugs (AEDs) in the elderly are highlighted. Studies have shown that people with epilepsy receiving AED treatment show important deficits in physical and social functioning compared with age-matched people without epilepsy. To what extent these deficits can be ascribed to epilepsy per se or to the consequences of AED treatment remains to be clarified. The importance of characterizing the effects of AEDs in an elderly population is highlighted by epidemiological surveys indicating that the prevalence of AED use is increased in elderly people, particularly in those living in nursing homes. Both the pharmacokinetics and the pharmacodynamics of AEDs may be altered in old age, which may contribute to the observation that AEDs are among the drug classes most commonly implicated as causing adverse drug reactions in an aged population. Age alone is one of several contributors to alterations in AED response in the elderly; other factors include physical frailty, co-morbidities, dietary influences, and drug interactions. Individualization of dosage, avoidance of unnecessary polypharmacy, and careful observation of clinical response are essential for an effective and safe utilization of AEDs in an elderly population.


Assuntos
Anticonvulsivantes/uso terapêutico , Epilepsia/tratamento farmacológico , Veteranos/estatística & dados numéricos , Idoso , Envelhecimento/fisiologia , Anticonvulsivantes/farmacocinética , Anticonvulsivantes/farmacologia , Instituição de Longa Permanência para Idosos , Humanos , Casas de Saúde , Fenitoína/farmacocinética , Polimedicação
15.
J Comp Pathol ; 127(4): 280-9, 2002 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-12443736

RESUMO

An increase in metallothionein I and II (MT I/II) mRNA concentrations has been reported in the central nervous system of scrapie-infected rodents. In this study we compared cattle with bovine spongiform encephalopathy (BSE), cattle affected by neurological disease other than BSE, and clinically healthy cattle in respect of MT I/II immunoreactivity in brainstem medullary tissue. Marked astrocytic MT I/II immunolabelling was seen in all BSE-affected animals, in contrast to clinically healthy cases, in which no such labelling was detected. In BSE, MT I/II immunoreactive astrocytes were confined specifically to areas of vacuolation or abnormal prion protein (PrP(BSE)) deposition, or both. MT I/II immunolabelling was also seen in a small number of animals with a neurological disease other than BSE. These findings complement previous studies by demonstrating increased levels of MT I/II in transmissible spongiform encephalopathy (TSE)-infected brain tissue, indicating that MT I/II may play some as yet unidentified role in the response to TSE infection.


Assuntos
Encefalopatia Espongiforme Bovina/metabolismo , Bulbo/metabolismo , Metalotioneína/metabolismo , Animais , Astrócitos/metabolismo , Astrócitos/patologia , Bovinos , Encefalopatia Espongiforme Bovina/patologia , Proteína Glial Fibrilar Ácida/metabolismo , Técnicas Imunoenzimáticas/veterinária , Bulbo/patologia , Proteínas do Tecido Nervoso/metabolismo , Príons/metabolismo
16.
J Ind Microbiol Biotechnol ; 29(2): 75-82, 2002 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-12161774

RESUMO

Bacteria isolated previously from ultrapure water (UPW) systems were examined for their ability to survive in UPW, with the ultimate goal of elucidating potential carbon and energy sources for the bacteria. Two strains of Ralstonia pickettii isolated from different areas within the UPW system (pretreatment and polishing loop, and referred to as strains 3A1 and MF254A, respectively) and a strain of Bradyrhizobium sp. were compared to increase our understanding of the fundamental behavior of bacteria contaminating UPW. R. pickettii (3A1) grew significantly slower in R2A medium, with a final cell yield much lower than the isolate from the polishing loop. In addition, R. pickettii MF254A showed a broader substrate range than either strain 3A1 or Bradyrhizobium sp. In UPW, there appears to be a threshold cell concentration (approximately 10(6) colony-forming units/ml), whereby the cell numbers remain constant for a prolonged period of 6 months or more. Below this concentration, rapid proliferation is observed until the threshold concentration is attained. Preliminary experiments suggested that nitrogen gas (frequently added to UPW storage tanks) may contribute to growth of Bradyrhizobium sp. Above the threshold concentration, the strain of Ralstonia sp. isolated from the polishing loop was capable of cryptic growth with heat-killed cells in UPW. However, cryptic growth was not observed when the cells supplied as nutrients were killed using UV254 light. Furthermore, cryptic growth did not appear to contribute significantly to proliferation of Bradyrhizobium sp. or Ralstonia sp. 3A1 (isolated from the pretreatment loop). We believe that cryptic growth may aid survival of the bacteria in UPW, but further experiments are warranted to prove this phenomenon conclusively.


Assuntos
Bacilos e Cocos Aeróbios Gram-Negativos/isolamento & purificação , Bacilos e Cocos Aeróbios Gram-Negativos/metabolismo , Microbiologia da Água , Purificação da Água , Contagem de Colônia Microbiana , Meio Ambiente , Bacilos e Cocos Aeróbios Gram-Negativos/classificação , Bacilos e Cocos Aeróbios Gram-Negativos/efeitos da radiação , Temperatura Alta , Fatores de Tempo , Raios Ultravioleta
17.
J Am Coll Cardiol ; 39(11): 1713-9, 2002 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-12039480

RESUMO

OBJECTIVES: The Air Primary Angioplasty in Myocardial Infarction (PAMI) study was designed to determine the best reperfusion strategy for patients with high-risk acute myocardial infarction (AMI) at hospitals without percutaneous transluminal coronary angioplasty (PTCA) capability. BACKGROUND: Previous studies have suggested that high-risk patients have better outcomes with primary PTCA than with thrombolytic therapy. It is unknown whether this advantage would be lost if the patient had to be transferred for PTCA, and reperfusion was delayed. METHODS: Patients with high-risk AMI (age >70 years, anterior MI, Killip class II/III, heart rate >100 beats/min or systolic BP <100 mm Hg) who were eligible for thrombolytic therapy were randomized to either transfer for primary PTCA or on-site thrombolysis. RESULTS: One hundred thirty-eight patients were randomized before the study ended (71 to transfer for PTCA and 67 to thrombolysis). The time from arrival to treatment was delayed in the transfer group (155 vs. 51 min, p < 0.0001), largely due to the initiation of transfer (43 min) and transport time (26 min). Patients randomized to transfer had a reduced hospital stay (6.1 +/- 4.3 vs. 7.5 +/- 4.3 days, p = 0.015) and less ischemia (12.7% vs. 31.8%, p = 0.007). At 30 days, a 38% reduction in major adverse cardiac events was observed for the transfer group; however, because of the inability to recruit the necessary sample size, this did not achieve statistical significance (8.4% vs. 13.6%, p = 0.331). CONCLUSIONS: Patients with high-risk AMI at hospitals without a catheterization laboratory may have an improved outcome when transferred for primary PTCA versus on-site thrombolysis; however, this will require further study. The marked delay in the transfer process suggests a role for triaging patients directly to specialized heart-attack centers.


Assuntos
Angioplastia Coronária com Balão , Infarto do Miocárdio/terapia , Transferência de Pacientes , Terapia Trombolítica , Idoso , Quimioterapia Combinada , Feminino , Fibrinolíticos/uso terapêutico , Humanos , Tempo de Internação/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/complicações , Infarto do Miocárdio/tratamento farmacológico , Infarto do Miocárdio/mortalidade , Fatores de Risco , Estreptoquinase/uso terapêutico , Fatores de Tempo , Ativador de Plasminogênio Tecidual/uso terapêutico , Resultado do Tratamento
18.
J Photochem Photobiol B ; 64(1): 55-61, 2001 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-11705730

RESUMO

Photodynamic therapy (PDT) invokes a number of cellular responses. Other studies have shown that PDT induces transcription and translation of heat shock proteins (Hsps). The expression of mitochondrial heat shock protein, Hsp60, was measured following in vitro Photofrin-mediated PDT in the colon cancer cell line HT29 and its PDT-induced resistant variant HT29-P14 as well as the radiation-induced fibrosarcoma cells RIF-1 and its PDT-induced resistant variant, RIF-8A. Basal levels of Hsp60 were found to be similar in the two murine cell lines. In the human model, the resistant HT29-P14 cell line showed a small increase in basal levels relative to its parental population. Incubation with Photofrin (PII) alone or photosensitization caused a significant increase in Hsp60 levels in all cell lines as determined by flow cytometry. A dose-dependent and temporal relationship for PDT response was observed, maximum levels were detected 6-8 h post PDT, at which time, Hsp60 induction was found to be significantly greater in the two resistant variants. Induction in the RIF cells was also found to be greater after incubation with PII alone at the highest doses tested. These results indicate that the presence of PII and the subsequent oxidative stress of PDT can induce Hsp60 and implicated it as a common factor that may contribute to the resistance observed in the induced resistant cells.


Assuntos
Chaperonina 60/biossíntese , Éter de Diematoporfirina/toxicidade , Fotoquimioterapia , Fármacos Fotossensibilizantes/toxicidade , Animais , Carcinoma , Chaperonina 60/metabolismo , Neoplasias do Colo , Ensaio de Unidades Formadoras de Colônias , Resistencia a Medicamentos Antineoplásicos , Fibrossarcoma , Citometria de Fluxo , Humanos , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Neoplasias Induzidas por Radiação , Células Tumorais Cultivadas
20.
Photochem Photobiol ; 73(6): 651-6, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11421071

RESUMO

Our approach to examine the mechanism(s) of action for photodynamic therapy (PDT) has been via the generation of PDT-resistant cell lines. In this study we used three human cell lines, namely, human colon adenocarcinoma (HT29), human bladder carcinoma and human neuroblastoma. The three photosensitizers used were Photofrin, Nile Blue A and aluminum phthalocyanine tetrasulfonate. The protocol for inducing resistance consisted of repeated in vitro photodynamic treatments with a photosensitizer to the 1-10%-survival level followed by regrowth of single surviving colonies. Varying degrees of resistance were observed. The three induced variants of the HT29 cell line were the most extensively studied. Their ratios of increased survival at the LD90 level range between 1.5- and 2.62-fold more resistant.


Assuntos
Fotoquimioterapia , Fármacos Fotossensibilizantes/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Resistência a Medicamentos , Células HT29 , Humanos , Fotobiologia , Células Tumorais Cultivadas , Ensaio Tumoral de Célula-Tronco
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