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1.
Ned Tijdschr Geneeskd ; 1672023 10 18.
Artigo em Holandês | MEDLINE | ID: mdl-37882433

RESUMO

A 58-year-old man presents with spontaneous brown discolorations of his mouth and hands. Our differential diagnosis included Peutz-Jeghers syndrome, Laugier-Hunziker syndrome or Addison's disease. There were no polyps in a previously performed colonoscopy and no other systemic symptoms. We made the diagnosis Laugier-Hunziker syndrome, a benign skin disorder that doesn't require treatment, confirmed by skin biopsy.


Assuntos
Hiperpigmentação , Doenças da Boca , Doenças da Unha , Unhas Malformadas , Síndrome de Peutz-Jeghers , Masculino , Humanos , Pessoa de Meia-Idade , Hiperpigmentação/patologia , Mucosa Bucal/patologia , Síndrome de Peutz-Jeghers/diagnóstico , Síndrome de Peutz-Jeghers/patologia , Doenças da Boca/diagnóstico , Doenças da Unha/diagnóstico
2.
J Burn Care Res ; 44(6): 1405-1412, 2023 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-37227902

RESUMO

Patients with extensive and complex wounds due to Necrotizing Soft-Tissue Infections (NSTI) may be referred to a burn center. This study describes the characteristics, outcomes, as well as diagnostic challenges of these patients. Patients admitted to three hospitals with a burn center for the treatment of NSTI in a 5-year period were included. Eighty patients (median age 54 years, 60% male) were identified, of whom 30 (38%) were referred by other centers, usually after survival of the initial septic phase. Those referred from other centers, compared to those primarily admitted to the study hospitals, were more likely to have group A streptococcal involvement (62% vs 35%, p = .02), larger wounds (median 7% vs 2% total body surface area, p < .001), and a longer length of stay (median 49 vs 22 days, p < .001). Despite a high incidence of septic shock (50%), the mortality rate was low (12%) for those primarily admitted. Approximately half (53%) of the patients were initially misdiagnosed upon presentation, which was associated with delay to first surgery (16 hours vs 4 hours, p < .001). Those initially misdiagnosed had more (severe) comorbidities, and less frequently reported pain or blue livid discoloration of the skin. This study underlines the burn centers' function as referral centers for extensively affected patients with NSTI. Besides the unique wound and reconstructive expertise, the low mortality rate indicates these centers provide adequate acute care as well. A major remaining challenge remains recognition of the disease upon presentation. Future studies in which factors associated with misdiagnosis are explored are needed.


Assuntos
Queimaduras , Choque Séptico , Infecções dos Tecidos Moles , Humanos , Masculino , Pessoa de Meia-Idade , Feminino , Unidades de Queimados , Estudos Retrospectivos , Queimaduras/complicações , Infecções dos Tecidos Moles/terapia , Choque Séptico/complicações
3.
Br J Surg ; 109(4): 332-339, 2022 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-35237788

RESUMO

BACKGROUND: Tangential excision of burned tissue followed by skin grafting is the cornerstone of burn surgery. Hydrosurgery has become popular for tangential excision, with the hypothesis that enhanced preservation of vital dermal tissue reduces scarring. The aim of this trial was to compare scar quality after hydrosurgical versus conventional debridement before split-skin grafting. METHODS: A double-blind randomized within-patient multicentre controlled trial was conducted in patients with burns that required split-skin grafting. One wound area was randomized to hydrosurgical debridement and the other to Weck knife debridement. The primary outcome was scar quality at 12 months, assessed with the observer part of the Patient and Observer Scar Assessment Scale (POSAS). Secondary outcomes included complications, scar quality, colour, pliability, and histological dermal preservation. RESULTS: Some 137 patients were randomized. At 12 months, scars of the hydrosurgical debrided wounds had a lower POSAS observer total item score (mean 2.42 (95 per cent c.i. 2.26 to 2.59) versus 2.54 (95 per cent c.i. 2.36 to 2.72; P = 0.023)) and overall opinion score (mean 3.08 (95 per cent c.i. 2.88 to 3.28) versus 3.30 (95 per cent c.i. 3.09-3.51); P = 0.006). Patient-reported scar quality and pliability measurements were significantly better for the hydrosurgically debrided wounds. Complication rates did not differ between both treatments. Histologically, significantly more dermis was preserved with hydrosurgery (P < 0.001). CONCLUSION: One year after surgery scar quality and pliability was better for hydrosurgically debrided burns, probably owing to enhanced histological preservation of dermis. REGISTRATION NUMBER: Trial NL6085 (NTR6232 (http://www.trialregister.nl)).


Assuntos
Queimaduras , Cicatriz , Queimaduras/patologia , Queimaduras/cirurgia , Cicatriz/etiologia , Desbridamento , Humanos , Pele/patologia , Transplante de Pele/efeitos adversos
4.
Wound Repair Regen ; 28(5): 666-675, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32570295

RESUMO

The treatment of burn wounds by enzymatic debridement using bromelain has shown promising results in our burn center. However, inadequate debridement occurred in a few cases in which the etiology of the burn was attributed to relatively low temperature burns. We hypothesized that bromelain is ineffective in burns in which collagen denaturation, which occurs approximately at 65°C, has not taken place. Our objective was to assess whether there is a relationship between the denaturation of collagen and the ability of bromelain to debride acute scald burn wounds of different temperatures. Ex vivo human skin from four different donors was cut into 1x1 cm samples, and scald burns were produced by immersion in water at temperatures of 40°C, 50°C, 60°C, 70°C, and 100°C for 20 minutes. Denaturation of collagen was assessed with histology, using hematoxylin and eosin (H&E) staining and a fluorescently labeled collagen hybridizing peptide (CHP), and with second harmonic generation (SHG) microscopy. Burned samples and one control sample (room temperature) were weighed before and after application of enzymatic debridement to assess the efficacy of enzymatic debridement. After enzymatic debridement, a weight reduction of 80% was seen in the samples heated to 70°C and 100°C, whereas the other samples showed a reduction of 20%. Unfolding of collagen, loss of basket-weave arrangement, and necrosis was seen in samples heated to 60°C or higher. Evident CHP fluorescence, indicative of collagen denaturation, was seen in samples of 60°C, 70°C and 100°C. SHG intensity, signifying intact collagen, was significantly lower in the 70°C and 100°C group (P <.05) compared to the lower temperatures. In conclusion, denaturation of collagen in skin samples occurred between 60°C and 70°C and strongly correlated with the efficacy of enzymatic debridement. Therefore, enzymatic debridement with the use of bromelain is ineffective in scald burns lower than 60°C.


Assuntos
Bromelaínas/farmacologia , Queimaduras/tratamento farmacológico , Desbridamento/métodos , Colágeno , Humanos , Técnicas In Vitro , Cicatrização/fisiologia
5.
Plast Reconstr Surg Glob Open ; 7(9): e2424, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31741815

RESUMO

Measurements of scar quality are essential to evaluate the effectiveness of scar treatments and to monitor scars. A large number of scar scales and measurement devices have been developed, which makes instrument selection challenging. The aim of this study was to provide an overview of the content (ie, included items) of all outcome measurement instruments that measure scar quality in different types of scars (burn, surgical, keloid, and necrotizing fasciitis), and the frequency at which the instruments and included items are used. METHODS: A systematic search was performed in PubMed and Embase.com up to October 31, 2018. All original studies reporting on instruments that measured at least 1 characteristic of scar quality were included and the instrument's content was extracted. RESULTS: We included 440 studies for data extraction. Included instruments (N = 909) were clinician-reported scales (41%), measurement devices (30%), patient-reported scales (26%), and combined clinician- and patient-reported scales (3%). The Observer scale of the Patient and Observer Scar Assessment Scale, the Cutometer, the Patient Scale of the Patient and Observer Scar Assessment Scale, and the modified Vancouver Scar Scale were the most often used instrument in each of these categories, respectively. The most frequent assessed items were thickness, vascularity, pigmentation, pliability, pain, and itch. CONCLUSION: The results of this study lay the foundation for our future research, which includes an international Delphi study among many scar experts, and an international focus group study among scar patients, aiming to elucidate how scar quality must be defined and measured from both professional and patient perspectives.

6.
J Wound Care ; 28(8): 548-554, 2019 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-31393796

RESUMO

OBJECTIVE: To compare the detection of bacteria in burn wounds between an bacterial fluorescence imaging device MolecuLight i:X, (Canada), and standard microbiological swabs. METHODS: Wounds were swabbed three times on one occasion; once with a standard swab, once with a high-fluorescent area swab, indicating a bacterial load >104 colony-forming units (CFU)/gram and a finally with a non-fluorescent (nF) area swab. Proportion agreement of the microbiological results was calculated and the accuracy of the device to detect relevant bacteria was assessed. RESULTS: A total of 14 patients with 20 wounds participated in the study. Median post-burn day at sampling time was 21 days. Of the 20 wounds, nine had a positive swab result in either of the three swabs, and 11 showed a highfluorescent area. Overall, positive and negative proportion agreement between standard swab and high-fluorescent swab sample results were 100%. Sensitivity, specificity, positive and negative predictive values of presence of high-fluorescence were 78%, 64%, 64%, and 78%, respectively. For Pseudomonas aeruginosa detection, these results were 100%, 70%, 44% and 100%, respectively. CONCLUSION: The diagnostic accuracy of the bacterial fluorescence imaging device to detect relevant bacteria in burn wounds was moderate and the reliability was equal to standard swabbing. Further research in larger sample sizes and on the relevance of minimal bacterial load and its potential to help with Pseudomonas aeruginosa management is needed.


Assuntos
Queimaduras , Imagem Óptica , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/isolamento & purificação , Infecção dos Ferimentos/microbiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Carga Bacteriana , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Projetos Piloto , Reprodutibilidade dos Testes , Adulto Jovem
7.
Wound Repair Regen ; 27(3): 257-267, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30675745

RESUMO

Although partial thickness burns are the most frequently reported burn injuries, there is no consensus on the optimal treatment. The objective of this study was to compare the clinical effectiveness and scar quality of Flaminal® Forte to silver sulfadiazine (Flamazine®) in the treatment of partial thickness burns. In this two-arm open label multicenter randomized controlled trial, adult patients with acute partial thickness burns and an affected total body surface area of less than 30% were randomized between Flaminal® Forte and Flamazine® and followed for 12 months. Dressing changes in the Flamazine® group were performed daily, and in the Flaminal® group during the first 3 days post burn and thereafter every other day until complete wound healing or surgery. Forty-one patients were randomly allocated to Flaminal® Forte and 48 patients to Flamazine®. The primary outcome was time to wound healing, which did not differ between the groups: median 18 days with Flaminal® Forte (range 8-49 days) versus 16 days with Flamazine® (range 7-48 days; p = 0.24). Regarding the secondary outcomes during hospital admission, there were no statistically significant differences between the groups concerning need for surgery, pain scores, pruritus, or pain-related and anticipatory anxiety. More patients in the Flaminal® group developed wound colonization (78% versus 32%, p < 0.001), but the treatment groups did not differ regarding the incidence of local infections and use of systemic antibiotics. In terms of scar quality, no statistically significant differences between both treatment groups were found regarding subjective scar assessment (Patient and Observer Scar Assessment Scale (POSAS)), scar melanin and pigmentation (DermaSpectrometer®), and scar elasticity and maximal extension (Cutometer®) during 12 month postburn. In conclusion, time to wound healing did not differ, but the use of Flaminal® Forte seemed favorable because less dressing changes are needed which lowers the burden of wound care.


Assuntos
Alginatos/uso terapêutico , Anti-Infecciosos Locais/uso terapêutico , Queimaduras/tratamento farmacológico , Cicatriz/patologia , Glucose Oxidase/uso terapêutico , Lactoperoxidase/uso terapêutico , Polietilenoglicóis/uso terapêutico , Sulfadiazina de Prata/uso terapêutico , Cicatrização/efeitos dos fármacos , Infecção dos Ferimentos/patologia , Adulto , Idoso , Alginatos/farmacologia , Anti-Infecciosos Locais/farmacologia , Queimaduras/patologia , Cicatriz/prevenção & controle , Combinação de Medicamentos , Feminino , Glucose Oxidase/farmacologia , Humanos , Lactoperoxidase/farmacologia , Masculino , Pessoa de Meia-Idade , Polietilenoglicóis/farmacologia , Reepitelização/efeitos dos fármacos , Sulfadiazina de Prata/farmacologia , Resultado do Tratamento , Cicatrização/fisiologia , Infecção dos Ferimentos/tratamento farmacológico
8.
Acta Derm Venereol ; 98(7): 636-640, 2018 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-29963682

RESUMO

Itch is a common problem after burns. Although the topic receives increasing attention, the number of prospective studies is limited. The aim of this study was to assess the influence of acute traumatic stress symptoms, controlled for injury characteristics, age and sex, on itch over a period of 18 months using multilevel analysis. A total of 226 respondents provided itch scores. Participants completed the Burn Itch Questionnaire during admission (n = 208) and at 3 (n =179), 12 (n =143) and 18 (n =99) months post-burn. They completed the Impact of Event Scale to assess acute traumatic stress symptoms during admission. Skin graft requirement, a higher level of acute traumatic stress symptoms and younger age were statistically significant predictors of a higher itch score. Younger age was particularly associated with higher itch scores during admission, whereas the effect of skin grafting was particularly observed at 3 months post-burn. This study replicates the predictive role of traumatic stress symptoms, which warrants further research.


Assuntos
Queimaduras/complicações , Prurido/etiologia , Estresse Psicológico/etiologia , Adolescente , Adulto , Idoso , Bélgica , Queimaduras/diagnóstico , Queimaduras/psicologia , Queimaduras/cirurgia , Distribuição de Qui-Quadrado , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Países Baixos , Prurido/diagnóstico , Prurido/psicologia , Fatores de Risco , Índice de Gravidade de Doença , Transplante de Pele , Estresse Psicológico/diagnóstico , Estresse Psicológico/psicologia , Inquéritos e Questionários , Fatores de Tempo , Resultado do Tratamento , Adulto Jovem
9.
Trials ; 19(1): 239, 2018 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-29673408

RESUMO

BACKGROUND: Deep dermal burns require tangential excision of non-viable tissue and skin grafting to improve wound healing and burn-scar quality. Tangential excision is conventionally performed with a knife, but during the last decade hydrosurgery has become popular as a new tool for tangential excision. Hydrosurgery is generally thought to be a more precise and controlled manner of burn debridement leading to preservation of viable tissue and, therefore, better scar quality. Although scar quality is considered to be one of the most important outcomes in burn surgery today, no randomized controlled study has compared the effect of these two common treatment modalities with scar quality as a primary outcome. The aim of this study is, therefore, to compare long-term scar quality after hydrosurgical versus conventional tangential excision in deep dermal burns. METHODS/DESIGN: A multicenter, randomized, intra-patient, controlled trial will be conducted in the Dutch burn centers of Rotterdam, Beverwijk, and Groningen. All patients with deep dermal burns that require excision and grafting are eligible. Exclusion criteria are: a burn wound < 50 cm2, total body surface area (TBSA) burned > 30%, full-thickness burns, chemical or electrical burns, infected wounds (clinical symptoms in combination with positive wound swabs), insufficient knowledge of the Dutch or English language, patients that are unlikely to comply with requirements of the study protocol and follow-up, and patients who are (temporarily) incompetent because of sedation and/or intubation. A total of 137 patients will be included. Comparable wound areas A and B will be appointed, randomized and either excised conventionally with a knife or with the hydrosurgery system. The primary outcome is scar quality measured by the observer score of the Patient and Observer Scar Assessment Scale (POSAS); a subjective scar-assessment instrument, consisting of two separate six-item scales (observer and patient) that are both scored on a 10-point rating scale. DISCUSSION: This study will contribute to the optimal surgical treatment of patients with deep dermal burn wounds. TRIAL REGISTRATION: Dutch Trial Register, NTR6232 . Registered on 23 January 2017.


Assuntos
Queimaduras/cirurgia , Cicatriz/patologia , Desbridamento/métodos , Procedimentos Cirúrgicos Dermatológicos/métodos , Pele/patologia , Irrigação Terapêutica/métodos , Cicatrização , Queimaduras/patologia , Cicatriz/etiologia , Desbridamento/efeitos adversos , Procedimentos Cirúrgicos Dermatológicos/efeitos adversos , Humanos , Estudos Multicêntricos como Assunto , Países Baixos , Ensaios Clínicos Controlados Aleatórios como Assunto , Pele/lesões , Transplante de Pele , Irrigação Terapêutica/efeitos adversos , Fatores de Tempo , Sobrevivência de Tecidos , Resultado do Tratamento
10.
Diabetes Res Clin Pract ; 106(3): 617-26, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25458327

RESUMO

AIMS: Since many type 2 diabetes patients experience postprandial hypotension, the aim of this study was to unravel meal-related changes in systemic hemodynamics and autonomic nervous system (ANS)-balance. METHODS: Forty-two age-matched males (15 type 2 diabetes; 12 metabolic syndrome; 15 controls) without overt autonomic neuropathy received a standardized high-fat mixed meal after an overnight fast. Hemodynamic variables were measured by finger plethysmography. Fourier analysis was used to calculate the low-/high-frequency (LF/HF)-ratio, a marker of autonomic nervous system-balance, and baroreceptor reflex sensitivity (BRS). RESULTS: Following the meal, diastolic blood pressure (DBP) decreased in type 2 diabetes patients only, paralleled by a significant decrement in systemic vascular resistance (SVR) and an increase in cardiac index. All groups showed an increase in postprandial heart rate. Controls, but not metabolic syndrome or type 2 diabetes patients, showed a meal-related increase in LF/HF-ratio. When combining all study subjects, homeostatic model assessment-insulin resistance (HOMA-IR) was inversely correlated with changes in DBP, SVR, LF/HF-ratio and BRS. CONCLUSIONS: Based on these data, we hypothesize that in patients with uncomplicated type 2 diabetes, insulin resistance hampers adequate meal-induced sympathetic activation, leading to a decrease in SVR and resulting in a postprandial drop in DBP.


Assuntos
Sistema Nervoso Autônomo/fisiopatologia , Pressão Sanguínea/fisiologia , Débito Cardíaco/fisiologia , Diabetes Mellitus Tipo 2/fisiopatologia , Período Pós-Prandial/fisiologia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade
11.
Metabolism ; 62(4): 568-77, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-23164480

RESUMO

AIM: Glucocorticoids impair glucose tolerance by inducing insulin resistance. We investigated the dose-dependent effects of glucocorticoid treatment on islet-cell function in healthy males and studied the role of the autonomic nervous system. DESIGN AND METHODS: A randomized, placebo-controlled, double-blind, dose-response intervention study was conducted in 32 healthy males (age: 21±2years; BMI: 21.9±1.7kg/m(2)). Participants were allocated to prednisolone 7.5mg once daily (n=12), prednisolone 30mg once daily (n=12), or placebo (n=8) for two weeks. Beta-cell function was measured by hyperglycemic clamp with arginine stimulation, glucagon levels were measured following a standardized meal test. RESULTS: We found that prednisolone treatment dose-dependently reduced C-peptide secretion following arginine stimulation on top of hyperglycemia (ASI-iAUCCP): -2.8 (-5.2;0.2) and -3.1 (-8.8; -1.0) nmolL(-1)min(-1) for prednisolone 7.5mg and prednisolone 30mg, respectively (P=0.035 vs. placebo). Fasting glucagon levels increased dose-dependently (vs. placebo; P=0.001), whereas postprandial glucagon levels were only increased by prednisolone 30mg. Changes in parasympathetic activity related with changes in fasting glucose levels (r=-0.407; P=0.03) and showed a trend towards correlation with fasting glucagon concentrations (r=-0.337; P=0.07). The change in sympathovagal balance was inversely related to ASI-iAUCCP (r=-0.365; P=0.05). CONCLUSION: We conclude that in addition to inducing insulin resistance, prednisolone treatment dose-dependently impaired islet-cell function. Altered sympathovagal balance may be related to these effects.


Assuntos
Glucocorticoides/toxicidade , Ilhotas Pancreáticas/efeitos dos fármacos , Pancreatopatias/induzido quimicamente , Sistema Nervoso Simpático/fisiopatologia , Nervo Vago/fisiopatologia , Adolescente , Adulto , Antropometria , Arginina/farmacologia , Glicemia/metabolismo , Relação Dose-Resposta a Droga , Método Duplo-Cego , Glucagon/sangue , Técnica Clamp de Glucose , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Humanos , Hiperglicemia/induzido quimicamente , Incretinas/metabolismo , Masculino , Pancreatopatias/fisiopatologia , Testes de Função Pancreática , Prednisolona/farmacologia , Estimulação Química , Adulto Jovem
12.
Clin Genet ; 80(1): 59-67, 2011 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20950376

RESUMO

Overwhelming evidence supports the theory that inflammatory bowel disease (IBD) is caused by a complex interplay between genetic predispositions of multiple genes, combined with an abnormal interaction with environmental factors. It is becoming apparent that epigenetic factors can have a significant contribution in the pathogenesis of disease. Changes in the methylation state of IBD-associated genes could significantly alter levels of gene expression, potentially contributing to disease onset and progression. We have explored the role of DNA methylation in IBD pathogenesis. DNA methylation profiles (1505 CpG sites of 807 genes) of matched diseased (n = 26) and non-diseased (n = 26) intestinal tissues from 26 patients with IBD [Crohn's disease (CD) n = 9, ulcerative colitis (UC) n = 17] were profiled using the GoldenGate™ methylation assay. After an initial identification of a panel of 50 differentially methylated CpG sites from a training set (14 non-diseased and 14 diseased tissues) and subsequent validation with a testing set (12 non-diseased and 12 diseased tissues), we identified seven CpG sites that are differentially methylated in intestinal tissues of IBD patients. We have also identified changes in DNA methylation associated with the two major IBD subtypes, CD and UC. This study reports IBD-associated changes in DNA methylation in intestinal tissue, which may be disease subtype-specific.


Assuntos
Metilação de DNA , Doenças Inflamatórias Intestinais/genética , Mucosa Intestinal/metabolismo , Análise por Conglomerados , Colite Ulcerativa/genética , Ilhas de CpG , Doença de Crohn/genética , Epigênese Genética , Feminino , Perfilação da Expressão Gênica , Humanos , Masculino
13.
Epidemiol Infect ; 131(2): 835-9, 2003 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-14596523

RESUMO

The Veterans Health Administration (VHA) of the Department of Veterans Affairs tracks legionella disease in the system of 172 medical centres and additional outpatient clinics using an annual census for reporting. In fiscal year 1999, 3.62 million persons were served by the VHA. From fiscal year 1989-1999, multiple intense interventions were carried out to decrease the number of cases and case rates for legionella disease. From fiscal year 1992-1999, the number of community-acquired and healthcare-associated cases decreased in the VHA by 77 and 95.5% respectively (P = 0.005 and 0.01). Case rates also decreased significantly for community and healthcare-associated cases (P = 0.02 and 0.001, respectively), with the VHA healthcare-associated case rates decreasing at a greater rate than VHA community-acquired case rates (P = 0.02). Over the time of the review, the VHA case rates demonstrated a greater decrease compared to the case rates for the United States as a whole (P = 0.02). Continued surveillance, centrally defined strategies, and local implementation can have a positive outcome for prevention of disease in a large, decentralized healthcare system.


Assuntos
Hospitais de Veteranos , Legionelose/epidemiologia , Veteranos/estatística & dados numéricos , Feminino , Humanos , Incidência , Modelos Lineares , Masculino , Vigilância da População , Estados Unidos/epidemiologia , United States Department of Veterans Affairs
14.
Cell Motil Cytoskeleton ; 27(3): 272-83, 1994.
Artigo em Inglês | MEDLINE | ID: mdl-8020112

RESUMO

The single alpha-tubulin gene of Tetrahymena thermophila was isolated from a genomic library and shown to encode a single protein. Comparisons of the rates of evolution of this gene with other alpha-tubulin sequences revealed that it belongs to a group of more evolutionarily constrained alpha-tubulin proteins in animals, plants, and protozoans versus the group of more rapidly evolving fungal and variant animal alpha-tubulins. The single alpha-tubulin of Tetrahymena must be used in a variety of microtubule structures, and we suggest that equivalently conserved alpha-tubulins in other organisms are evolutionarily constrained because they, too, are multifunctional. Reduced constraints on fungal tubulins are consistent with their simpler microtubule systems. The animal variant alpha-tubulins may also have diverged because of fewer functional requirements or they could be examples of specialized tubulins. To analyze the role of tubulin gene expression in regulation of the complex microtubule system of Tetrahymena, alpha-tubulin mRNA amounts were examined in a number of cell states. Message levels increased in growing versus starved cells and also during early stages of conjugation. These changes were correlated with increases in transcription rates. Additionally, alpha-tubulin mRNA levels oscillate in a cell cycle dependent fashion caused by changes in both transcription and decay rates. Therefore, as in other organisms, Tetrahymena adjusts alpha-tubulin message amounts via message decay. However the complex control of alpha-tubulin mRNA during the Tetrahymena life cycle involves regulation of both decay and transcription rates.


Assuntos
Regulação da Expressão Gênica , Genes de Protozoários , Tetrahymena thermophila/genética , Tubulina (Proteína)/genética , Sequência de Aminoácidos , Grupos de População Animal/genética , Animais , Sequência de Bases , Clonagem Molecular , Humanos , Dados de Sequência Molecular , Filogenia , Plantas/genética , Homologia de Sequência de Aminoácidos , Especificidade da Espécie , Tetrahymena thermophila/fisiologia , Tubulina (Proteína)/biossíntese
15.
Appl Opt ; 13(11): 2716-8, 1974 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-20134760

RESUMO

Transmission and reflection measurements in the infrared region between 340 and 40 cm(-1) are presented for Irtrans 1-6. Measurements have been performed at room temperature and at liquid nitrogen and liquid helium temperatures.

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