RESUMO
Open-book examinations (OBEs) will likely become increasingly important assessment tools. We investigated how access to open-book resources affected questions testing factual recall, which might be easy to look-up, versus questions testing higher-order cognitive domains. Few studies have investigated OBEs using modern Internet resources or as summative assessments. We compared performance on an examination conducted as a traditional closed-book exam (CBE) in 2019 (N = 320) and a remote OBE with free access to Internet resources in 2020 (N = 337) due to COVID-19. This summative, end-of-year assessment focused on basic science for second-year medical students. We categorized questions by Bloom's taxonomy ('Remember', versus 'Understand/Apply'). We predicted higher performance on the OBE, driven by higher performance on 'Remember' questions. We used an item-centric analysis by using performance per item over all examinees as the outcome variable in logistic regression, with terms 'Open-Book, 'Bloom Category' and their interaction. Performance was higher on OBE questions than CBE questions (OR 2.2, 95% CI: 2.14-2.39), and higher on 'Remember' than 'Understand/Apply' questions (OR 1.13, 95% CI: 1.09-1.19). The difference in performance between 'Remember' and 'Understand/Apply' questions was greater in the OBE than the CBE ('Open-Book' * 'Bloom Category' interaction: OR 1.2, 95% CI: 1.19-1.37). Access to open-book resources had a greater effect on performance on factual recall questions than higher-order questions, though performance was higher in the OBE overall. OBE design must consider how searching for information affects performance, particularly on questions measuring different domains of knowledge.
Assuntos
COVID-19 , Estudantes de Medicina , COVID-19/diagnóstico , COVID-19/epidemiologia , Cognição , Avaliação Educacional , Humanos , Faculdades de MedicinaRESUMO
Intestinal type gastric cancer is a significant cause of mortality, therefore a better understanding of its molecular basis is required. We assessed if either aneuploidy or activity of the oncogenic transcription factor nuclear factor kappa B (NF-kappaB), increased incrementally during pre-malignant gastric histological progression and also if they correlated with each other in patient samples, as they are both induced by oxygen free radicals. In a prospective study of 54 (aneuploidy) and 59 (NF-kappaB) consecutive patients, aneuploidy was assessed by interphase fluorescent in situ hybridisation (FISH) for chromosome 1. NF-kappaB was assessed by expression of interleukin-8 (IL-8), and in a subset, by immunohistochemistry (IHC) for active p65. Aneuploidy levels increased incrementally across the histological series. 2.76% of cells with normal histology (95% CI, 2.14-3.38%) showed background levels of aneuploidy, this increased to averages of 3.78% (95% CI, 3.21-4.35%), 5.89% (95% CI, 3.72-8.06%) and 7.29% (95% CI, 4.73-9.85%) of cells from patients with gastritis, Helicobacter pylori positive gastritis and atrophy/intestinal metaplasia (IM) respectively. IL-8 expression was only increased in patients with current H. pylori infection. NF-kappaB analysis showed some increased p65 activity in inflamed tissues. IL-8 expression and aneuploidy level were not linked in individual patients. Aneuploidy levels increased incrementally during histological progression; were significantly elevated at very early stages of neoplastic progression and could well be linked to cancer development and used to assess cancer risk. Reactive oxygen species (ROS) induced in early gastric cancer are presumably responsible for the stepwise accumulation of this particular mutation, i.e. aneuploidy. Hence, aneuploidy measured by fluorescent in situ hybridisation (FISH) coupled to brush cytology, would be worthy of consideration as a predictive marker in gastric cancer and could be clinically useful in pre-malignant disease to stratify patients by their cancer risk.
Assuntos
Aneuploidia , Biomarcadores Tumorais/genética , Cromossomos Humanos Par 1/genética , Gastrite/genética , Neoplasias Intestinais/genética , Neoplasias Gástricas/genética , Biomarcadores Tumorais/metabolismo , Mucosa Gástrica/metabolismo , Mucosa Gástrica/patologia , Gastrite/diagnóstico , Humanos , Técnicas Imunoenzimáticas , Hibridização in Situ Fluorescente , Interleucina-8/genética , Interleucina-8/metabolismo , Neoplasias Intestinais/diagnóstico , NF-kappa B/genética , NF-kappa B/metabolismo , Prognóstico , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Neoplasias Gástricas/diagnósticoRESUMO
A 5-month-old female was referred to the paediatric surgery clinic with a neck swelling in the right supra-clavicular region. This was thought clinically to be cystic hygroma. Pathology showed an ectopic salivary gland. This should be added to the list of differential diagnoses of neck swelling in childhood.
Assuntos
Coristoma , Glândulas Salivares , Feminino , Humanos , Lactente , PescoçoRESUMO
A current review of nutritional complications following bariatric procedures is presented, focusing on the most common and clinically important deficiencies. A brief outline of nutritional supplementation protocol is presented, highlighting the need for a standardized, national or international set of guidelines for pre- and postoperative nutritional screening and appropriate supplementation.
Assuntos
Deficiência de Vitaminas/etiologia , Cirurgia Bariátrica/efeitos adversos , Cálcio/deficiência , Deficiência de Ácido Fólico/etiologia , Deficiências de Ferro , Desnutrição/etiologia , HumanosRESUMO
The Canadian Total Diet Study is a national survey to determine the level of chemical contaminants in the Canadian food supply. Food samples were collected from Whitehorse, Yukon, supermarkets as part of the study in 1998. Whitehorse was chosen as a sampling centre, despite its small population (n = 19,000), to determine if residue levels were different in foods available in northern communities relative to levels observed in previous studies in the more populated south. Foods were prepared as for consumption before pesticide residue analysis. Residue levels observed in most foods were similar to levels observed in samples from previous surveys from southern Canadian cities. Malathion and DDE (1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene), a transformation product of DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl(ethane), were the two most frequently detected compounds (26.4 and 25.8%, respectively). The majority of pesticides, however, had a detection frequency of < 5%. In general, pesticides in food composites were well below maximum residue limits established in the Canadian Food and Drug Regulations. Chlorpropham and captan had the highest dietary intakes (2.16 and 1.94 micrograms (kg body weight-day)-1, respectively), based on the results from Whitehorse. No dietary intakes above the acceptable daily intakes, however, were observed for any of the 39 pesticides investigated in any age-sex category, where an acceptable daily intake has been proposed.
Assuntos
Inquéritos sobre Dietas , Análise de Alimentos/métodos , Contaminação de Alimentos/análise , Resíduos de Praguicidas/análise , Adolescente , Adulto , Idoso , Animais , Canadá , Criança , Pré-Escolar , Feminino , Peixes , Frutas/química , Humanos , Hidrocarbonetos Clorados , Lactente , Inseticidas/análise , Masculino , Concentração Máxima Permitida , Pessoa de Meia-Idade , Compostos Organofosforados , Verduras/química , YukonRESUMO
Assessment of percutaneous absorption in vitro provides key information when predicting dermal absorption in vivo. Confirmation of skin membrane integrity is an essential component of the in vitro method, as described in test guideline OECD 428. Historically, assessment of the membrane's permeability to tritiated water (T2O) and the generation of a permeability coefficient (Kp) were used to confirm that the skin membrane was intact prior to application of the test penetrant. Measuring electrical resistance (ER) across the membrane is a simpler, quicker, safer and more cost effective method. To investigate the robustness of the ER integrity measure, the Kp values for T2O for a range of human and animal skin membranes were compared with corresponding ER data. Overall, for human, rat, pig, mouse, rabbit and guinea pig skin, the ER data gave a good inverse association with the corresponding Kp values; the higher the Kp the lower the ER values. In addition, the distribution across a large dataset for individual skin samples was similar for Kp and ER, allowing a cut-off value for ER to be established for each skin type. Based on CTL's (Syngenta Central Toxicology Laboratory) standard static diffusion cells and databridge, we propose that intact skin should have an ER equal to or above (in kOmega): human (10), mouse (5) guinea pig (5), pig (4) rat (3), and rabbit (0.8). We conclude that measurement of ER across in vitro skin membranes provides a robust measurement of skin barrier integrity and is an appropriate alternative to Kp for T2O in order to identify intact membranes that have acceptable permeability characteristics for in vitro percutaneous absorption studies.
Assuntos
Impedância Elétrica , Absorção Cutânea , Pele/metabolismo , Trítio/farmacocinética , Administração Tópica , Animais , Epiderme/metabolismo , Feminino , Cobaias , Humanos , Técnicas In Vitro , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Pessoa de Meia-Idade , Permeabilidade , Guias de Prática Clínica como Assunto , Coelhos , Ratos , Suínos , Trítio/administração & dosagem , Trítio/normas , Água/administração & dosagem , Água/normasRESUMO
The crucian carp retina was used to study the effects of the melatonin antagonist p697 (N-pentanoyl 2-benzyltryptamine) and the melatonin agonists [+]- and [-]-AMMTC (N-acetyl-4-aminomethyl-6-methoxy-9-methyl-1,2,3,4-tetrahydrocarbazol e) on horizontal cell spinule formation, an indicator of the state of retinal adaptation. DH97 was capable of both counteracting dark-adaptive spinule degradation and inducing light-adaptive spinule formation at the beginning of the dark phase. Addition of dopamine receptor blockers opposed the action of DH97 on spinules, with SCH 23930, a D1 dopamine receptor antagonist, being more effective than the D2 receptor antagonist sulpiride. DH97 induced a twofold increase in dopamine release. We conclude that melatonin acts as a dark signal within the teleost retina by inhibiting the dopaminergic system. In accordance with this, both enantiomers of AMMTC prevented light-induced spinule formation, and reduced dopamine release to below dark-adaptive baseline levels. We suggest that the suppression of spinule formation by AMMTC may be due to either a direct inhibitory interaction between the melatonin agonist and horizontal cell dopamine D1 receptors, or an inhibitory effect on the activity of the dopamine-releasing interplexiform cells.
Assuntos
Dopamina/metabolismo , Melatonina/agonistas , Melatonina/antagonistas & inibidores , Retina/metabolismo , Triptaminas/farmacologia , Adaptação Ocular/fisiologia , Animais , Carbazóis/farmacologia , Cromatografia Líquida de Alta Pressão , Ritmo Circadiano/fisiologia , Adaptação à Escuridão/fisiologia , Dopamina/análise , Carpa Dourada , Microscopia Eletrônica , Plasticidade Neuronal/fisiologia , Retina/efeitos dos fármacos , Retina/ultraestruturaRESUMO
The alpha-glucosidase enzyme was isolated from vegetative cells and spores of Bacillus stearothermophilus, ATCC 7953. Spore-associated enzyme had a molecular weight of approximately 92,700, a temperature optimum of 60 degrees C, and a pH optimum of 7.0-7.5. The enzyme in crude aqueous spore extract was stable for 30 min up to a temperature of 65 degrees C, above which the enzyme was rapidly denatured. The optimal pH for stability of the enzyme was approximately 7.2. The alpha-glucosidase in crude vegetative cell extract had similar characteristics to the spore-associated enzyme but its molecular weight was 86,700. The vegetative cell and spore-associated enzymes were cross-reactive. The enzymes are postulated to derive from a single gene product, which undergoes modification to produce the spore-associated form. The location of alpha-glucosidase in the spore coats (outside the spore protoplast) is consistent with the location of most enzymes involved in activation, germination and outgrowth.
Assuntos
Proteínas de Bactérias/análise , Geobacillus stearothermophilus/enzimologia , Vapor , Esterilização/métodos , alfa-Glucosidases/análise , Animais , Biomarcadores/análise , Geobacillus stearothermophilus/fisiologia , Temperatura Alta , Concentração de Íons de Hidrogênio , Camundongos , Camundongos Endogâmicos BALB C , Esporos Bacterianos/enzimologia , Fatores de TempoRESUMO
Market basket samples representative of food from six Canadian cities were surveyed from 1992 to 1996. Fifty composites of fatty foods, prepared for consumption were analysed for 40 PCB congeners by gas chromatography-mass spectrometry. Fish and butter contained the highest total PCB concentrations, while milk and infant foods contained the lowest. The dairy and meat composites were major contributors to the total PCB intake of 5.7 ng/kg/day, and to the TEQ (2,3,7,8-tetrachloro-p-dibenzodioxin equivalent) intake of 0.11 pg/kg/day. The pattern of congeners was similar for the different food groups with the exception of fish, which contained less tri- and tetra-chlorinated biphenyls and more of the hexachlorinated congener No. 153.
Assuntos
Poluentes Ambientais/análise , Contaminação de Alimentos , Resíduos de Praguicidas/análise , Bifenilos Policlorados/análise , Animais , Canadá , Cromatografia Gasosa , Laticínios/análise , Gorduras na Dieta , Peixes , Humanos , Alimentos Infantis/análise , Espectrometria de Massas , Carne/análiseRESUMO
Tetrahydrocyclopent[b]indoles, tetrahydrocarbazoles, and hexahydrocyclohept[b]indoles have been prepared as melatonin analogues to investigate the nature of the binding site of the melatonin receptor. The affinity of analogues was compared in a radioligand binding assay using chicken brain membranes and agonist and antagonist potency measured in clonal Xenopus laevis melanophore cells. Comparison of the N-acyl-3-amino-6-methoxytetrahydrocarbazoles (2) with N-acyl-4-(aminomethyl)-6-methoxy-9-methyltetrahydrocarbazoles (9) showed that the latter have much higher binding affinities for the chicken brain receptor. Comparison of N-acyl-1-(aminomethyl)-7-methoxy-4-methyltetrahydrocyclopent[b]ind oles (10), 6-methoxytetrahydrocarbazoles (9), and N-acyl-10-(aminomethyl)-2-methoxy-5-methylhexahydrocyclohept[b]ind oles (11) showed that the tetrahydrocarbazoles had the highest binding affinity with the cyclohept[b]indoles and the cyclopent[b]indoles having rather lower affinities. All of these observations are in agreement with our postulated model of melatonin orientation at the binding pocket in which the 3-amidoethane side chain is in a conformation close to the 5-methoxyl group, as is shown in the X-ray crystallographic structure of 9m and in the energy-minimized computed structures. Separation of the enantiomers of members from each of these three systems was accomplished by chiral HPLC. It was found that in all cases the (-)-enantiomer had a higher binding affinity than the (+)-enantiomer. An X-ray crystallographic analysis of the two enantiomers of 9a showed that the (+)-enantiomer had the (R) absolute stereochemistry. Since the sign of the Cotton curves, determined from circular dichroism studies, was the same for all (+)-enantiomers, it is assumed that the absolute stereochemistry at these centers is identical. In the Xenopus melanophore assay, the tetrahydrocarbazoles 2 (R = H) were mainly weak antagonists, while those with R = OMe were agonists. The biological behavior of the tetrahydrocarbazoles 9 (R = H) depended on R1, some being agonists and some antagonists, whereas those with R = OMe were generally agonists. Variation of the R and R1 groups in compounds of type 9 produced both agonists and antagonists. The tetrahydrocylopentaindoles 10 had similar biological properties to the corresponding analogues of 9, but the hexahydrocycloheptaindoles 11 showed a much greater propensity to be antagonists. In all cases the (S)-enantiomers were found to be more potent agonists than the (R)-enantiomers.
Assuntos
Carbazóis/síntese química , Indóis/síntese química , Receptores de Superfície Celular/agonistas , Receptores de Superfície Celular/antagonistas & inibidores , Receptores Citoplasmáticos e Nucleares/agonistas , Receptores Citoplasmáticos e Nucleares/antagonistas & inibidores , Animais , Ligação Competitiva , Encéfalo/metabolismo , Carbazóis/química , Carbazóis/farmacologia , Membrana Celular/metabolismo , Galinhas , Cristalografia por Raios X , Indicadores e Reagentes , Indóis/química , Indóis/farmacologia , Melanóforos/citologia , Melanóforos/efeitos dos fármacos , Melanóforos/fisiologia , Melatonina/metabolismo , Modelos Moleculares , Conformação Molecular , Receptores de Melatonina , Relação Estrutura-Atividade , Xenopus laevisRESUMO
1. In this study we compared the vasoconstrictor activity of melatonin in rat isolated tail artery using two different recording systems, the Halpern pressure myograph and the Halpern-Mulvany wire myograph, with the view to determining a reliable method for obtaining pharmacological data on vascular melatonin receptors. In addition, we characterized the melatonin receptor in this preparation, using analogues of melatonin, and examined the activity of various naphthalenic derivatives with biological activity in non-vascular models of melatonin receptors. 2. Using the Halpern pressure myograph, cumulative addition of melatonin (0.1 nM to 1 microM) produced direct vasoconstriction (19.3+/-6.4% reduction in lumen diameter, n=5) in five of 11 pressurized segments, with pEC50 of 9.14+/-0.17. Similarly, non-cumulative application of melatonin caused vasoconstriction (19.7+/-4.6% reduction in lumen diameter, n=7) in seven of 20 preparations examined with pEC50 of 8.74+/-0.26. The selective alpha2-adrenoceptor agonist, UK-14304 (5-bromo-6-[2-imidazolin-2-ylamino]-quinoxaline bitartrate), produced vasoconstriction in all 'melatonin-insensitive' preparations. 3. Melatonin (0.1 nM to 1 microM) failed to elicit isometric contractions of tail artery segments in the Halpern wire myograph, but produced concentration-dependent potentiation of electrically-evoked, isometric contractions (maximum effect of 150-200% enhancement) when applied either noncumulatively (seven of seven preparations) or cumulatively (four of seven preparations). The pEC50 value of melatonin (non-cumulative) was 8.50+/-0.10 (n=7) which was not different from that obtained in the pressure myograph. All further experiments were conducted using a non-cumulative protocol against electrically-evoked, isometric contractions. 4. Based on the pEC50 values for the melatonin analogues examined, the pharmacological profile for the enhancement of electrically-evoked contractions was 2-iodomelatonin > 6-chloromelatonin > or = (-)-AMMTC > or = S21634 > or = melatonin > or = S20098 > S20242 > or = S20304 > 6-hydroxymelatonin > S20932 > (+)-AMMTC > N-acetyl-5-HT. Our data suggests the vascular receptor belongs to the MEL1-like subtype. All the indole-based analogues of melatonin, 2-iodomelatonin, (-)-AMMTC, (+)-AMMTC, S20932, 6-chloromelatonin, 6-hydroxymelatonin and N-acetyl-5-HT, behaved as full agonists. All the naphthalenic derivatives examined, S21634, S20098, S20242 and S20304 behaved as partial agonists relative to melatonin. 5. The naphthalenic-based antagonists, S20928 and S20929, did not modify electrically-evoked, isometric contractions of the tail artery, but produced a parallel, rightward displacement of the melatonin concentration-response curve. Based upon the effect of 1 microM S20928 and S20929, the estimated pK(B) values for these antagonists were 7.18+/-0.25 (n=4) and 7.17+/-0.25 (n=5), respectively. 6. We demonstrated that enhancement of electrically-evoked, isometric contractions of the rat isolated tail artery (using the Halpern-Mulvany wire myograph) is a simple and reproducible model for assessing the activity of putative agonists, partial agonists and antagonists at vascular melatonin receptors. Pharmacological characterization of the receptor suggests the presence of a MEL1-like subtype.
Assuntos
Sequestradores de Radicais Livres/farmacologia , Melatonina/farmacologia , Receptores de Superfície Celular/agonistas , Receptores Citoplasmáticos e Nucleares/agonistas , Vasoconstrição/efeitos dos fármacos , Animais , Artérias/efeitos dos fármacos , Relação Dose-Resposta a Droga , Masculino , Melatonina/análogos & derivados , Naftalenos/farmacologia , Ratos , Ratos Wistar , Receptores de Melatonina , Vasoconstritores/farmacologiaRESUMO
Five strains of Bacillus stearothermophilus have been studied to identify a spore strain to be used as a biological indicator organism for low temperature steam and formaldehyde sterilization. Three strains gave poor reproducibility of batch size and growth index and were discarded. The other two strains gave good reproducibility with a high growth index and gave rise to linear survivor curves when exposed to 5% aqueous formaldehyde. However, only NCIMB 8224 sporulates on a simpler medium and as it was the most resistant to formaldehyde, it was further studied. Tests were carried out in a modified miniclave and factors studied included temperature of the steam and formaldehyde concentration. All studies confirmed the suitability of this strain as a biological indicator organism.
Assuntos
Geobacillus stearothermophilus/efeitos dos fármacos , Esterilização/métodos , Interpretação Estatística de Dados , Relação Dose-Resposta a Droga , Formaldeído/farmacologia , Geobacillus stearothermophilus/crescimento & desenvolvimento , Reprodutibilidade dos Testes , Esporos Bacterianos/efeitos dos fármacos , Esporos Bacterianos/crescimento & desenvolvimento , Vapor , TemperaturaRESUMO
Melatonin, a hormone secreted by the pineal gland, can act on the central circadian oscillator in the suprachiasmatic nucleus of the hypothalamus. It has been proposed that melatonin or its analogues may be useful in restoring disturbed circadian rhythms in jet-lag, shift-work and some blind subjects, and as sleep-promoting agents. In the present study, the (-)- and (+)-enantiomers of N-acetyl-4-aminomethyl-6-methoxy-9-methyl-1,2,3,4-tetrahydrocarbazole (AMMTC) were separated and tested. The affinity of the enantiomers at the specific 2-[125I]iodomelatonin binding site in chick brain membranes was compared in competition assays, and their biological activity in a specific melatonin receptor bioassay, aggregation of pigment granules in Xenopus laevis melanophores. The (-)-enantiomer of AMMTC was 130-fold and 230-fold more potent than the (+)-enantiomer in competition radioligand binding assays and melanophores, respectively. Both enantiomers are melatonin receptor agonists; (-)-AMMTC is slightly more potent than melatonin itself. As the tetrahydrocarbazole nucleus holds the C-3 amido side-chain of AMMTC in a restricted conformation, the analogues will be useful in modelling the melatonin receptor binding site.
Assuntos
Carbazóis/farmacologia , Ritmo Circadiano/efeitos dos fármacos , Melatonina/farmacologia , Animais , Ligação Competitiva , Encéfalo/metabolismo , Carbazóis/administração & dosagem , Galinhas , Radioisótopos do Iodo , Dose Letal Mediana , Melanóforos/metabolismo , Melatonina/análogos & derivados , Glândula Pineal/metabolismo , Ensaio Radioligante , Estereoisomerismo , Xenopus laevisRESUMO
This study estimated prospectively the prevalence of high drug and alcohol levels in road trauma cases who met the criteria for activation of the Liverpool Hospital's trauma team. Urine analysis of road trauma victims between October 1992 and October 1993 was undertaken for drug and alcohol estimation. A total of 164 drivers were studied. A urine alcohol concentration (UAC) exceeding 0.08 g/dL was detected in 27 drivers (16.5%). Cannabinoids were detected in the urine of 25 drivers (15.2%), in 17 the concentrations exceeded 400 ng/mL. In one instance amphetamine, cocaine and heroin were detected in the same injured driver. Combined use of alcohol with some other drugs was detected in only four drivers. Alcohol and cannabinoid levels were prevalent in the urine of injured drivers in this study, particularly in young males who remain over-represented in the group of injured drivers. In the population surveyed other drugs were rarely detected. The role of cannabinoids in road trauma and the use of cannabinoids in young male drivers will however need to be monitored more extensively.
Assuntos
Acidentes de Trânsito/estatística & dados numéricos , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Ferimentos e Lesões/etiologia , Adulto , Fatores Etários , Intoxicação Alcoólica/complicações , Intoxicação Alcoólica/diagnóstico , Intoxicação Alcoólica/epidemiologia , Intoxicação Alcoólica/urina , Canabinoides/efeitos adversos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , New South Wales/epidemiologia , Fatores Sexuais , Transtornos Relacionados ao Uso de Substâncias/diagnóstico , Ferimentos e Lesões/epidemiologiaRESUMO
Preliminary screening was carried out on spores of 29 strains of Bacillus stearothermophilus to determine their potential as biological indicator organisms for low temperature steam and formaldehyde sterilization. Each strain was sporulated on four chemically defined media. Fourteen strains produced satisfactory sporulation on one or more of the media but there was considerable variation in the extent of sporulation. The growth index of the spores, which was dependent on both the strain of organism and the sporulation medium, ranged from 1% to 90%. The spores were appraised on the basis of their resistance to inactivation by 0.5% w/v formaldehyde in aqueous solution at 70 degrees C. The survivor curves obtained could be characterized into five types on the basis of the shape of the curve. Only five strains of Bacillus stearothermophilus produced spores with the characteristics of high resistance, linear semi-logarithmic survivor curve and high growth index that would be required of a potential biological indicator organism.
Assuntos
Formaldeído , Geobacillus stearothermophilus/fisiologia , Esterilização , Meios de Cultura , Resistência Microbiana a Medicamentos , Formaldeído/farmacologia , Geobacillus stearothermophilus/efeitos dos fármacos , Geobacillus stearothermophilus/crescimento & desenvolvimento , Especificidade da Espécie , Esporos Bacterianos/efeitos dos fármacos , Esporos Bacterianos/fisiologia , Vapor , TemperaturaRESUMO
The role of the phrA gene in the genetic control of photoreactivation in Escherichia coli has been a matter of some controversy. It has been proposed that the gene has no significant physiological role in photoreactivation. However, we have previously sequenced a restriction fragment thought to contain the phrA gene and shown it to contain a putative gene. When this gene, termed the putative phrA gene, was transformed into a phrAphrB mutant, a photoreactivable response above that of the phrAphrB mutant was observed. It has been suggested that the photorepair seen in phrB mutants is due to Type III photoreactivation, which is independent of temperature and fluence rate effects. Here we have shown that the photorecovery associated with the phrA gene is dependent on both temperature and fluence rate. This suggests that the photorecovery is not due to Type III photoreactivation but to an enzymatic reaction caused by an unknown photoactive protein, the phrA gene product, which acts on lesions other than pyrimidine dimers, possibly pyrimidine (6-4) pyrimidone photoproducts. We therefore propose that the phrA gene be reaccepted and its role in photoreactivation in Escherichia coli acknowledged.
Assuntos
Transportadores de Cassetes de Ligação de ATP , Proteínas de Bactérias/genética , Proteínas de Escherichia coli , Escherichia coli/genética , Genes Bacterianos , Cromossomos Bacterianos , Relação Dose-Resposta à Radiação , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/efeitos da radiação , Mutagênese , Plasmídeos , Mapeamento por Restrição , TemperaturaRESUMO
In 1992, Welsh Water withdrew the successful water fluoridation scheme on Anglesey. Despite evidence of the benefits of water fluoridation and the rise in number of children with tooth decay since the scheme's withdrawal, Welsh Water is still not prepared to re-establish the scheme.
Assuntos
Fluoretação , Pré-Escolar , Índice CPO , Cárie Dentária/epidemiologia , Cárie Dentária/prevenção & controle , Humanos , Privatização , País de Gales/epidemiologiaRESUMO
Anti-neutrophil cytoplasmic antibodies (ANCA) are antibodies directed against enzymes that are found mainly within the azurophil or primary granules of neutrophils. There are 3 types of ANCA that can be distinguished by the patterns they produce by indirect immunofluorescence when tested on normal ethanol-fixed neutrophils. Diffuse fine granular cytoplasmic fluorescence (cANCA) is typically found in Wegener's granulomatosis, in some cases of microscopic polyarteritis and Churg Strauss syndrome, and in some cases of crescentic and segmental necrotising glomerulonephritis, but it is rare in other conditions. The target antigen is usually proteinase 3. Perinuclear fluorescence (pANCA) is found in many cases of microscopic polyarteritis and in other cases of crescentic and segmental necrotising glomerulonephritis. These antibodies are often directed against myeloperoxidase but other targets include elastase, cathepsin G, lactoferrin, lysozyme and beta-glucuronidase. The third group designated "atypical" ANCA includes neutrophil nuclear fluorescence and some unusual cytoplasmic patterns, and while a few of the target antigens are shared with pANCA, the others have not been identified. Sera that produce a pANCA or atypical ANCA pattern on alcohol-fixed neutrophils result in cytoplasmic fluorescence when formalin acetone fixation is used. pANCA or atypical ANCA occur in about 2/3 of all individuals with ulcerative colitis or primary sclerosing cholangitis, and they are found in a third of patients with Crohn's disease. The reported incidence of ANCA in rheumatoid arthritis and SLE varies considerably but the patterns are predominantly pANCA and atypical ANCA.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Arterite/imunologia , Autoanticorpos/análise , Granulomatose com Poliangiite/imunologia , Inflamação/imunologia , Animais , Anticorpos Anticitoplasma de Neutrófilos , Biomarcadores/análise , Modelos Animais de Doenças , Imunofluorescência , Granulomatose com Poliangiite/tratamento farmacológico , Humanos , RatosRESUMO
Over the course of the last decade, research conducted by the Imperial College Environmental Geochemistry Research Group has focused on the nature and effects of lead in UK dusts and soils. An initial nationwide reconnaissance survey demonstrated that approximately 10% of the population is exposed to lead levels in excess of 2,000 µg g(-1) in house-hold dust. Subsequent exposure studies revealed that for 2 year old children in the UK urban environment, approximately 50% of lead intake was from dust ingested as a result of hand-to-mouth activity. Follow-up computer controlled scanning electron microscopy (CCSEM) analysis of urban household dust and particulate material wiped from children's hands showed that important sources of dust lead include lead-based paint, road dust and soils. CCSEM identification of specific soil lead tracer particles (from minewaste contaminated soils) in dusts and on children's hands further documented the important role of soil as a source of exposure. Speciation studies of soil lead of this origin indicated that the form of the lead, which is largely influenced by the soil environment, is the primary control on bioavailability. It appears that although lead of minewaste origin may be present at elevated levels in dusts and soils, it does not necessarily contribute to elevated blood lead levels when the lead is present in relatively insoluble form.