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1.
Br J Dermatol ; 182(4): 849-859, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31381131

RESUMEN

BACKGROUND: Exposure to artificial tanning devices is carcinogenic to humans, and government regulations to restrict or ban indoor tanning appear to be increasing. OBJECTIVES: We evaluated changes in the international prevalence of indoor tanning among adolescents and adults after artificial tanning devices were classified as carcinogenic by the International Agency for Research on Cancer (IARC) in 2009. METHODS: Systematic searches in PubMed and Web of Science databases were undertaken. Overall, 43 studies reporting 'ever' or 'past-year' indoor tanning exposure after 2009 were identified. We used metaregression analysis to evaluate the prevalence of indoor tanning over time. Random effects meta-analysis was used to summarize the prevalence of indoor tanning in adolescents and adults according to sex, region and presence of age prohibitions. RESULTS: Global prevalence of indoor tanning in adolescents for 2013-2018 was 6·5% [95% confidence interval (CI) 3·3-10·6], 70% lower than the 22·0% (95% CI 17·2-26·8) prevalence for 2007-2012. Among adults, the prevalence was 10·4% (95% CI 5·7-16·3) for 2013-2018, a decrease of 35% from 18·2% for 2007-2012. Since 2009, the overall past-year prevalence among adolescents was 6·7% (95% CI 4·4-9·6) and 12·5% (95% CI 9·5-15·6) among adults. The prevalence of tanning indoors in the past year was similar in North America (adults, 12·5%; adolescents, 7·6%) and Europe (adults, 11·1%; adolescents, 5·1%). In 2009, three countries had regulations restricting indoor tanning, compared with 26 countries today. CONCLUSIONS: Prevalence of indoor tanning has declined substantially and significantly in adolescents and adults since the 2009 IARC statement, reflecting the rise in regulations that limit this source of unnecessary exposure to carcinogenic ultraviolet radiation. What is already known about this topic? Indoor tanning is associated with an increased risk of melanoma. A meta-analysis of worldwide indoor tanning prevalence for 1986-2012 found a past-year prevalence of 18% in adolescents and 14% in adults, with higher prevalences during the period 2007-2012. Policies to regulate indoor tanning began to be implemented across the globe in 2009. Only one study carried out in the U.S.A. has evaluated the efficacy of such policies in reducing indoor tanning prevalence. What does this study add? For the period 2013-2018, we found indoor tanning prevalences of 6·7% in adolescents and 11·9% in adults. This implies a reduction in indoor tanning use of 70% in adolescents and 35% in adults during the last 10 years. Our study encourages policy makers to strengthen indoor tanning regulations that reduce sunbed use among the general population in order to produce maximum public health benefit.


Asunto(s)
Neoplasias Cutáneas , Baño de Sol , Adolescente , Adulto , Europa (Continente) , Humanos , Agencias Internacionales , América del Norte , Prevalencia , Neoplasias Cutáneas/epidemiología , Neoplasias Cutáneas/etiología , Neoplasias Cutáneas/prevención & control , Rayos Ultravioleta/efectos adversos
2.
Br J Dermatol ; 180(3): 631-636, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30005137

RESUMEN

BACKGROUND: The incidence of skin cancer in organ transplant recipients (OTRs) is very high, due mainly to long-term immunosuppressive therapy. The problem is particularly severe for OTRs living in Queensland, Australia, and results in significant mortality. OBJECTIVES: To describe the experience of the first dedicated outpatient high-throughput transplant skin clinic in Queensland. METHODS: This prospective evaluation study was conducted at a newly established, outpatient transplant skin cancer surgery and surveillance clinic. Participants (89 OTRs and 12 non-OTRs) were referred to the Princess Alexandra Hospital Transplant Skin Clinic during December 2016 to May 2017, and were each followed for 3 months. Self-completed questionnaires were administered at baseline and the end of follow-up (n = 94), and details of any skin cancers occurring in that period were extracted from hospital records. RESULTS: In the 3-month follow-up of 101 participants, a total of 615 skin lesions were detected in the 3-month follow-up of 101 participants, of which 478 (78%) were treated in the clinic and 55 (9%) were referred to another specialist. Of the 478 treated lesions, 268 were histopathologically confirmed skin cancers, equivalent to 2·7 (95% confidence interval 2·5-2·8) skin cancers per participant per 3 months. The overall number needed to treat for any skin cancer was 1·4 (95% confidence interval 1·3-1·5). Three-quarters (374) of in-clinic treatments were surgical, and most (90%) were complete excisions. The median time from detection of skin cancer to excision was 7 days. CONCLUSIONS: This high-volume surgical outpatient transplant skin clinic enables efficient treatment of skin cancers in very-high-risk OTRs.


Asunto(s)
Procedimientos Quirúrgicos Dermatologicos/estadística & datos numéricos , Hospitales de Alto Volumen/estadística & datos numéricos , Trasplante de Órganos/efectos adversos , Servicio Ambulatorio en Hospital/organización & administración , Neoplasias Cutáneas/cirugía , Femenino , Estudios de Seguimiento , Rechazo de Injerto/inmunología , Rechazo de Injerto/prevención & control , Humanos , Terapia de Inmunosupresión/efectos adversos , Incidencia , Masculino , Persona de Mediana Edad , Servicio Ambulatorio en Hospital/estadística & datos numéricos , Evaluación de Programas y Proyectos de Salud , Estudios Prospectivos , Queensland , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/epidemiología , Neoplasias Cutáneas/etiología , Receptores de Trasplantes/estadística & datos numéricos
3.
J Eur Acad Dermatol Venereol ; 33(7): 1290-1296, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-30706970

RESUMEN

BACKGROUND: A long-term complication among organ transplant recipients (OTRs) is skin malignancies which are associated with level and duration of immunosuppressive treatment, sun exposure and age. Dermatological surveillance is recommended for OTRs at high risk of skin malignancies, but evidence is lacking on the benefits of such services. OBJECTIVE: To examine the economic impact on patients and on the hospital service of a multidisciplinary high-throughput skin cancer clinic in Brisbane, Australia, dedicated to dermatological and surgical care of high-risk OTRs. METHODS: In a pre/postdesign, hospital admission and cost data were obtained for 101 consecutively enrolled study participants from 12 months prior to the introduction of the clinic (to February 2016), the 3-month 'run-in' period (March to May 2016) and 12 months subsequent (to June 2017). Differences between pre- and post-clinic hospital costs were tested using non-parametric bootstrapping and interrupted time series analysis. A survey of patient out-of-pocket costs and perceived financial burden was also undertaken during the clinic. RESULTS: Overall hospital costs were higher after the clinic but 3-monthly hospital costs for skin procedures trended downwards. Despite 3-monthly mean, hospital visits increasing from 85 to 314, mean 3-monthly costs reduced by AU$1491 (P < 0.001) indicating greater cost efficiency. Total patient out-of-pocket costs were AU$18 377 over 3 months. CONCLUSION: Clinical costing data revealed higher, more rapid throughput and significantly lower per patient costs pre- and postestablishment of a multidisciplinary skin cancer clinic for OTRs.


Asunto(s)
Gastos en Salud/estadística & datos numéricos , Costos de Hospital/estadística & datos numéricos , Hospitalización/economía , Trasplante de Órganos/economía , Servicio Ambulatorio en Hospital/economía , Neoplasias Cutáneas/economía , Anciano , Australia , Detección Precoz del Cáncer/economía , Femenino , Hospitalización/estadística & datos numéricos , Humanos , Análisis de Series de Tiempo Interrumpido , Masculino , Persona de Mediana Edad , Grupo de Atención al Paciente , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/cirugía
4.
Artículo en Inglés | MEDLINE | ID: mdl-26423576

RESUMEN

The purpose of this study was to understand the extent, nature and variability of the current economic burden of prostate cancer among Australian men. An online cross-sectional survey was developed that combined pre-existing economic measures and new questions. With few exceptions, the online survey was viable and acceptable to participants. The main outcomes were self-reported out-of-pocket costs of prostate cancer diagnosis and treatment, changes in employment status and household finances. Men were recruited from prostate cancer support groups throughout Australia. Descriptive statistical analyses were undertaken. A total of 289 men responded to the survey during April and June 2013. Our study found that men recently diagnosed (within 16 months of the survey) (n = 65) reported spending a median AU$8000 (interquartile range AU$14 000) for their cancer treatment while 75% of men spent up to AU$17 000 (2012). Twenty per cent of all men found the cost of treating their prostate cancer caused them 'a great deal' of distress. The findings suggest a large variability in medical costs for prostate cancer treatment with 5% of men spending $250 or less in out-of-pocket expenses and some men facing very high costs. On average, respondents in paid employment at diagnosis stated that they had retired 4-5 years earlier than planned.


Asunto(s)
Costo de Enfermedad , Gastos en Salud , Neoplasias de la Próstata/terapia , Adulto , Anciano , Australia , Estudios Transversales , Empleo/economía , Humanos , Masculino , Persona de Mediana Edad , Neoplasias de la Próstata/complicaciones , Neoplasias de la Próstata/economía , Jubilación/economía , Estudios Retrospectivos
5.
Health Res Policy Syst ; 14: 2, 2016 Jan 12.
Artículo en Inglés | MEDLINE | ID: mdl-26754325

RESUMEN

BACKGROUND: The interest and activity in measuring and reporting the impact of publicly funded health and medical research has grown rapidly in recent years. Research evaluation typically relies on researchers for much of the information for an impact assessment. However, the acceptability and feasibility of this activity among health researchers is unknown. The aim of this study was to understand the role and opinions of cancer researchers in the growing area of impact evaluation activity, to inform the logistics of a sustainable program of impact evaluation. METHODS: A brief anonymous online survey was administered to 95 current and past grant recipients funded through the external grants program at Cancer Council New South Wales. Eleven survey statements were constructed with Likert responses and supplemented with two open-ended questions. The statements covered the conceptual, attitudinal and practical aspects of impact evaluation. The survey targeted researchers from the full spectrum of cancer control research classifications. Descriptive analyses obtained response frequencies and percentages. RESULTS: Forty-five cancer researchers completed the survey (response rate 47%) and 77% were Associate Professors or Professors. Responses were polarised for questions relating to engaging with research end-users, perceived time-pressure to collate data, and pressure to produce research outputs. Some researchers emphasised that quality was an important goal over quantity and warned that collecting impact data created incentives and disincentives for researchers. CONCLUSION: There was mixed support and acceptance among senior cancer researchers in Australia on their perceived role and engagement with research impact activities. Sole reliance on researchers for collating and reporting impact data may be problematic. Requesting information from researchers could be minimised and confined to final reports and possible verification of externally-led evaluations.


Asunto(s)
Investigación Biomédica/organización & administración , Difusión de la Información/métodos , Neoplasias/fisiopatología , Rol Profesional , Investigadores/psicología , Actitud , Australia , Humanos , Neoplasias/prevención & control , Neoplasias/terapia , Factores de Tiempo , Investigación Biomédica Traslacional/organización & administración
6.
Eur J Cancer Care (Engl) ; 24(6): 854-61, 2015 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-26121998

RESUMEN

UNLABELLED: In patients with colorectal cancer, a trial of a telephone-delivered multiple health behaviour change intervention, using acceptance commitment therapy strategies, found benefits for health and psychosocial outcomes including increased physical activity, improved dietary habits and lower body mass index. Our aim was to address the health economic outcomes by assessing the health system cost and health utility impacts of the intervention. A cost-consequences analysis was performed using data from a two-group randomised controlled intervention trial (n = 410). Outcomes included health-related quality of life (HRQoL), health utility and health system costs. At 12 months, clinically meaningful improvements were found for SF-6D over time but no significant differences were found between groups (P = 0.95). The cost of delivering the 6-month intervention was on average €280 per person and made up 21% of overall healthcare costs for participants during the intervention period. Excluding intervention costs, costs were similar for health professional visits and medications across groups. Despite significant positive intervention effects on health behaviours, health utility and HRQoL scores were similar across groups. On the basis that intervention costs were small and physical activity, diet and weight management improved, on balance the intervention is potentially a worthwhile investment in healthcare funds. TRIAL REGISTRATION: ACTRN12608000399392.


Asunto(s)
Neoplasias Colorrectales/rehabilitación , Dieta , Ejercicio Físico , Conductas Relacionadas con la Salud , Costos de la Atención en Salud , Sobrevivientes , Teléfono , Adulto , Anciano , Anciano de 80 o más Años , Análisis Costo-Beneficio , Femenino , Estado de Salud , Humanos , Estilo de Vida , Masculino , Persona de Mediana Edad , Calidad de Vida , Adulto Joven
8.
Br J Surg ; 98(11): 1589-98, 2011 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-22059235

RESUMEN

BACKGROUND: This study examined the interaction between natural history, current practice patterns in diagnosis, monitoring and treatment of oesophageal cancer, and associated health resource utilization and costs. METHODS: A cost analysis of a prospective population-based cohort of 1100 patients with a primary diagnosis of oesophageal cancer was performed using chart review from the Australian Cancer Study Clinical Follow-Up Study. The analysis enabled estimation of healthcare resources and associated costs in 2009 euros by stage of disease and treatment pathway. RESULTS: Most patients (88·5 per cent) presented with stage II, III or IV cancer; 61·1 per cent (672 of 1100) were treated surgically. Overall mean costs were €37,195 (median €29,114) for patients undergoing surgery and €17,281 (median €13,066) for those treated without surgery. Surgery contributed 66·4 per cent of the total costs (mean €24,697 per patient) in the surgical group. In the non-surgical group, use of chemotherapy was more prevalent (81·9 per cent of patients) and contributed 61·1 per cent of the total costs. Other important cost determinants were gastro-oesophageal junction tumours, treatment location and tumour stage. Mean costs of those monitored for Barrett's oesophagus (7·3 per cent of patients) were lower, although about one-third still presented with advanced-stage cancer. CONCLUSION: Overall costs for managing oesophageal cancer were high and dominated by surgery costs in patients treated surgically and by chemotherapy costs in patients treated without surgery. Radiotherapy, treatment location and cancer subtype were also important. Monitoring for Barrett's oesophagus and earlier-stage detection were associated with lower management costs, but the potential net benefit from surveillance strategies needs further investigation.


Asunto(s)
Adenocarcinoma/economía , Carcinoma de Células Escamosas/economía , Neoplasias Esofágicas/economía , Unión Esofagogástrica , Recursos en Salud/estadística & datos numéricos , Adenocarcinoma/diagnóstico , Adenocarcinoma/terapia , Adolescente , Adulto , Anciano , Australia , Esófago de Barrett/diagnóstico , Esófago de Barrett/economía , Esófago de Barrett/terapia , Carcinoma de Células Escamosas/diagnóstico , Carcinoma de Células Escamosas/terapia , Análisis Costo-Beneficio , Neoplasias Esofágicas/diagnóstico , Neoplasias Esofágicas/terapia , Femenino , Costos de la Atención en Salud , Recursos en Salud/economía , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Cuidados Posoperatorios/economía , Estudios Prospectivos , Adulto Joven
9.
Skin Health Dis ; 1(3): e51, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-35663144

RESUMEN

Background: Non-melanoma skin cancers (NMSCs) are common and consume many healthcare resources. A health utility is a single preference-based value for assessing health-related quality of life, which can be used in economic evaluations. There are scarce data on health utilities for NMSCs. Objectives: Using a systematic review approach, we synthesized the current data on NMSC-related health utilities. Methods: A systematic review of studies of NMSC-related health utilities was conducted in Medline, Embase, and Cochrane databases. Data were extracted based on the protocol and a quality assessment was performed for each study. Results: The protocol resulted in 16 studies, involving 121 621 participants. Mean utility values across the studies ranged from 0.56 to 1 for undifferentiated NMSC, 0.84 to 1 for actinic keratosis, 0.45 to 1 for squamous cell carcinoma, and 0.67 to 1 for basal cell carcinoma. There was considerable variability in utilities by type of cancer, stage of diagnosis, time to treatment, treatment modality, and quality of life instrument or method. Utility values were predominantly based on the EuroQol 5-dimension instrument and ranged from 0.45 to 0.96, while other measurement methods produced values ranging from 0.67 to 1. Lower utility values were observed for advanced cancers and for the time period during and immediately after treatment, after which values gradually returned to pre-treatment levels. Conclusions: Most utility values clustered around relatively high values of 0.8 to 1, suggesting small decrements in quality of life associated with most NMSCs and their precursors. Variability in utilities indicates that careful characterization is required for measures to be used in economic evaluations.

10.
J Hosp Infect ; 105(2): 146-153, 2020 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-32179134

RESUMEN

BACKGROUND: Carbapenem-producing Enterobacterales are an expanding group of Gram-negative bacteria that are resistant to carbapenems and cause over 9000 cases of hospital-associated infections in the USA. Efforts to quantify the economic and societal burden to healthcare are important to inform resource planning to implement infection control programmes. AIM: We estimated the healthcare costs during an outbreak of carbapenemase-producing Escherichia coli OXA-181 in Australia. We aimed to understand the economic burden to hospitals of patients who are asymptomatically colonized with high-risk bacteria. METHODS: Hospital admissions data and associated costs were obtained from the State Health Department. Colonized patients were matched to non-colonized patients on age, sex, admission ward and diagnostic category. Mean healthcare costs and length of stay were examined using generalized linear models and accounted for time-dependent bias, patient age and ward location. FINDINGS: On average, colonized patients had six times higher mean costs (AU$155,784; 95% confidence interval (CI): AU$77,892-285,604) than non-colonized patients (AU$25,964). Mean costs for those aged 75-79 years were 50% lower (P=0.02) compared with the youngest subgroup, 35-39 years of age. The mean extended length of stay was 12 days (95% CI: 3-21) for colonized patients. Nursing care was the main driver of overall costs for colonized (44%) and non-colonized (39%) patients. CONCLUSION: Patients colonized with carbapenem-producing Enterobacterales during an official hospital outbreak incurred higher costs than non-colonized patients. Although infected patients incur substantial economic burden to hospitals, the costs incurred by colonized patients is also high.


Asunto(s)
Infecciones Asintomáticas/economía , Infecciones por Escherichia coli/economía , Escherichia coli/efectos de los fármacos , Precios de Hospital/estadística & datos numéricos , Hospitalización/economía , Adulto , Anciano , Anciano de 80 o más Años , Infecciones Asintomáticas/epidemiología , Australia/epidemiología , Proteínas Bacterianas , Infección Hospitalaria/economía , Infección Hospitalaria/epidemiología , Brotes de Enfermedades , Escherichia coli/enzimología , Escherichia coli/fisiología , Infecciones por Escherichia coli/epidemiología , Femenino , Hospitalización/estadística & datos numéricos , Humanos , Tiempo de Internación/estadística & datos numéricos , Masculino , Persona de Mediana Edad , beta-Lactamasas
12.
Biochim Biophys Acta ; 1108(1): 8-12, 1992 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-1643083

RESUMEN

The effects of step-changes in the ionic composition of the serosal medium bathing the toad urinary bladder under voltage-clamped conditions have been studied. A decrease in the K+ concentration from 4 to 3 mmol/l in the serosal fluid increased transiently the transepithelial current which after 30 min returned to the initial value. The peak current was reached after 3 min. The current response of the bladder to the reverse step in K+ concentration, from 3 to 4 mmol/l was much smaller. Surprisingly, the partial replacement of Cl- with gluconate produced a transient increase in current. It is suggested that secondary active transport plays an important role in this phenomenon and leads to an increased apical Na+ conductance. The second phases of the biphasic responses to Na/K+ and Cl-/gluconate substitutions have been interpreted as osmotic effects. Since the exchange of solutions in these studies was isoosmotic but not necessarily isotonic, experiments were also performed with osmotic changes in the serosal fluid for the purpose of comparison.


Asunto(s)
Vejiga Urinaria/fisiología , Animales , Bario/farmacología , Transporte Biológico , Bufo marinus , Electrofisiología , Epitelio/fisiología , Femenino , Técnicas In Vitro , Concentración Osmolar , Potasio/metabolismo , Vejiga Urinaria/efectos de los fármacos
13.
Biochim Biophys Acta ; 436(3): 541-56, 1976 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-952910

RESUMEN

It is already well-established that conduction in lipid bilayers containing alamethicin arises from the presence of complexes in which there are several molecules of the polypeptide. It is with the nature of these complexes that this paper is primarily concerned. While it is clear that increasing alamethicin concentration and increasing potential across the membrane favour their formation, the nature of the reactions involved has not yet been elucidated. Attempts have therefore been made to clarify the sequence of events leading to the establishment of a complex in its conducting state. It has been concluded that the most likely mechanism involves, initially, a non-field-dependent aggregation of the alamethicin, in the plane of the membrane, into non-conducting oligomers. These then appear to undergo movement normal to the membrane (which is field dependent) to form the conducting species. Temperature studies have shown that the various conducting states of the oligomer have effectively equal enthalpies, and that the activation energies for transitions between these states are all approx. 1.2kcal/mol. The corresponding rate constants are very sensitive to the lipid composition of the membrane and a variety of different systems has been examined in order to clarify the origins of this effect. The only conclusion from this part of the work is that lipid fluidity might be involved.


Asunto(s)
Alameticina , Antibacterianos , Colesterol , Glicéridos , Membranas Artificiales , Fosfolípidos , Conductividad Eléctrica , Cinética , Matemática , Modelos Biológicos , Relación Estructura-Actividad , Temperatura , Termodinámica
14.
Diabetes Res Clin Pract ; 104(1): 103-11, 2014 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-24503043

RESUMEN

AIM: To assess the cost-effectiveness of an automated telephone-linked care intervention, Australian TLC Diabetes, delivered over 6 months to patients with established Type 2 diabetes mellitus and high glycated haemoglobin level, compared to usual care. METHODS: A Markov model was designed to synthesize data from a randomized controlled trial of TLC Diabetes (n=120) and other published evidence. The 5-year model consisted of three health states related to glycaemic control: 'sub-optimal' HbA1c ≥58mmol/mol (7.5%); 'average' ≥48-57mmol/mol (6.5-7.4%) and 'optimal' <48mmol/mol (6.5%) and a fourth state 'all-cause death'. Key outcomes of the model include discounted health system costs and quality-adjusted life years (QALYS) using SF-6D utility weights. Univariate and probabilistic sensitivity analyses were undertaken. RESULTS: Annual medication costs for the intervention group were lower than usual care [ INTERVENTION: £1076 (95%CI: £947, £1206) versus usual care £1271 (95%CI: £1115, £1428) p=0.052]. The estimated mean cost for intervention group participants over five years, including the intervention cost, was £17,152 versus £17,835 for the usual care group. The corresponding mean QALYs were 3.381 (SD 0.40) for the intervention group and 3.377 (SD 0.41) for the usual care group. Results were sensitive to the model duration, utility values and medication costs. CONCLUSION: The Australian TLC Diabetes intervention was a low-cost investment for individuals with established diabetes and may result in medication cost-savings to the health system. Although QALYs were similar between groups, other benefits arising from the intervention should also be considered when determining the overall value of this strategy.


Asunto(s)
Análisis Costo-Beneficio , Diabetes Mellitus Tipo 2/economía , Costos de la Atención en Salud , Telemedicina/economía , Teléfono , Adolescente , Adulto , Anciano , Glucemia/metabolismo , Diabetes Mellitus Tipo 2/sangre , Diabetes Mellitus Tipo 2/terapia , Femenino , Estudios de Seguimiento , Hemoglobina Glucada/metabolismo , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven
19.
J Physiol ; 406: 371-92, 1988 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-3151079

RESUMEN

1. The effects of changes in media osmolality on the transepithelial current through the toad urinary bladder under voltage-clamp conditions have been studied. Over the limited range (+/- 24 mosmol/kg H2O) used in these investigations, changes in the osmolality of the mucosal bathing fluid produced no changes in transepithelial current. 2. Changes in osmolality of the serosal fluid greatly affected the transepithelial current with a decrease (increase) in osmolality producing a sustained increase (decrease) in current. 3. The changes in steady-state current were approximately proportional to the magnitude of the osmotic steps and were reproducible and reversible if the osmolalities of the solutions were confined to a domain of 220-260 mosmol/kg H2O. 4. Amiloride, which was used to block all active current, also eliminated the electrical responses to an osmotic pulse, indicating that the responses were of cellular origin. 5. The effects of substituting gluconate for medium chloride were examined. Similar responses were observed, indicating that they were not due to changes in a plasma membrane chloride conductance. 6. The transient currents observed during the changes from one steady state to the other often contained an oscillatory component, the amplitude and the degree of damping of which varied between bladders. The amplitude of the oscillations, but not their frequency, could be varied by altering the magnitude of the osmotic pulse and by changing the imposed transepithelial voltage. Decreasing the electrical potential of the mucosal solution with respect to that of the serosal solution decreased the amplitude of the oscillations, as did increased serosal potassium or substitution of gluconate for serosal chloride. The period of the oscillations always remained within the range of 9-12 min. 7. The results suggest that two major processes are initiated by an osmotic step in the serosal bathing medium. The first involves the establishment of new ion gradients and the second, alterations in sodium pump activity. In addition, there is evidence for a voltage-dependent sodium conductance in the apical membrane.


Asunto(s)
Vejiga Urinaria/fisiología , Potenciales de Acción/efectos de los fármacos , Amilorida/farmacología , Animales , Transporte Biológico Activo , Bufo marinus , Medios de Cultivo , Epitelio/fisiología , Femenino , Gluconatos , Técnicas In Vitro , Soluciones Isotónicas , Membrana Mucosa/fisiología , Concentración Osmolar , Solución de Ringer , Membrana Serosa/fisiología
20.
J Membr Biol ; 44(3-4): 309-19, 1978 Dec 29.
Artículo en Inglés | MEDLINE | ID: mdl-110941

RESUMEN

Toad urinary bladders were mounted in Ussing-type chambers and volt-age-clamped. At nonzero voltages only, small fluctuations in current, delta I, and therefore in tissue conductance, delta Gt, were detected. These fluctuations were caused by the smooth muscle of the underlying tissue which could be monitored continuously and simultaneously with the current, I. Inhibition of the smooth muscle contraction with verapamil (2 X 10(-5) M) abolished the fluctuations in I and Gt. Amiloride (10(-4) M) had no significant effect on the magnitude of delta Gt, oxytocin increased Gt without affecting delta Gt, and mucosal hypertonicity produced by mannitol increased delta Gt. These results are consistent with the hypothesis that two parallel pathways exist for passive current flow across the toad urinary bladder: one, the cellular pathway, was not affected by smooth muscle activity; the other, the paracellular pathway, was the route whose conductance was altered by the action of the smooth muscle. Thus the relationship between the cellular and shunt conductances of the epithelium of the toad urinary bladder, under a variety of conditions, can be investigated by utilizing the effects of the movement of the smooth muscle.


Asunto(s)
Potenciales de la Membrana/efectos de los fármacos , Vejiga Urinaria/metabolismo , Amilorida/farmacología , Animales , Bufo marinus/fisiología , Epitelio/metabolismo , Femenino , Técnicas In Vitro , Manitol/farmacología , Músculo Liso/metabolismo , Oxitocina/farmacología , Verapamilo/farmacología
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