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1.
PLoS Med ; 21(5): e1004393, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38820246

RESUMEN

BACKGROUND: HIV is a potent risk factor for tuberculosis (TB). Therefore, community-wide universal testing and treatment for HIV (UTT) could contribute to TB control, but evidence for this is limited. Community-wide TB screening can decrease population-level TB prevalence. Combining UTT with TB screening could therefore significantly impact TB control in sub-Saharan Africa, but to our knowledge there is no evidence for this combined approach. METHODS AND FINDINGS: HPTN 071 (PopART) was a community-randomised trial conducted between November 2013 to July 2018; 21 Zambian and South African communities (with a total population of approximately 1 million individuals) were randomised to arms A (community-wide UTT and TB screening), B (community-wide universal HIV testing with treatment following national guidelines and TB screening), or C (standard-of-care). In a cohort of randomly selected adults (18 to 44 years) enrolled between 2013 and 2015 from all 21 communities (total size 38,474; 27,139 [71%] female; 8,004 [21%] HIV positive) and followed-up annually for 36 months to measure the population-level impact of the interventions, data on self-reported TB treatment in the previous 12 months (self-reported TB) were collected by trained research assistants and recorded using a structured questionnaire at each study visit. In this prespecified analysis of the trial, self-reported TB incidence rates were measured by calendar year between 2014 and 2017/2018. A p-value ≤0.05 on hypothesis testing was defined as reaching statistical significance. Between January 2014 and July 2018, 38,287 individuals were followed-up: 494 self-reported TB during 104,877 person-years. Overall incidence rates were similar across all arms in 2014 and 2015 (0.33 to 0.46/100 person-years). In 2016 incidence rates were lower in arm A compared to C overall (adjusted rate ratio [aRR] 0.48 [95% confidence interval (95% CI) 0.28 to 0.81; p = 0.01]), with statistical significance reached. In 2017/2018, while incidence rates were lower in arm A compared to C, statistical significance was not reached (aRR 0.58 [95% CI 0.27 to 1.22; p = 0.13]). Among people living with HIV (PLHIV) incidence rates were lower in arm A compared to C in 2016 (RR 0.56 [95% CI 0.29 to 1.08; p = 0.08]) and 2017/2018 (RR 0.50 [95% CI 0.26 to 0.95; p = 0.04]); statistical significance was only reached in 2017/2018. Incidence rates in arms B and C were similar, overall and among PLHIV. Among HIV-negative individuals, there were too few events for cross-arm comparisons. Study limitations include the use of self-report which may have been subject to under-reporting, limited covariate adjustment due to the small number of events, and high losses to follow-up over time. CONCLUSIONS: In this study, community-wide UTT and TB screening resulted in substantially lower TB incidence among PLHIV at population-level, compared to standard-of-care, with statistical significance reached in the final study year. There was also some evidence this translated to a decrease in self-reported TB incidence overall in the population. Reduction in arm A but not B suggests UTT drove the observed effect. Our data support the role of UTT in TB control, in addition to HIV control, in high TB/HIV burden settings. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01900977.


Asunto(s)
Infecciones por VIH , Tamizaje Masivo , Tuberculosis , Humanos , Zambia/epidemiología , Sudáfrica/epidemiología , Adulto , Infecciones por VIH/epidemiología , Infecciones por VIH/diagnóstico , Infecciones por VIH/tratamiento farmacológico , Incidencia , Femenino , Masculino , Tuberculosis/epidemiología , Tuberculosis/diagnóstico , Tamizaje Masivo/métodos , Adulto Joven , Autoinforme , Adolescente , Prueba de VIH
3.
Trop Med Int Health ; 20(5): 589-606, 2015 May.
Artículo en Inglés | MEDLINE | ID: mdl-25641212

RESUMEN

OBJECTIVE: The Demographic and Health Surveys (DHS) are a vital data resource for cross-country comparative analyses. This study is part of a set of analyses assessing the types of providers being used for reproductive and maternal health care across 57 countries. Here, we examine some of the challenges encountered using DHS data for this purpose, present the provider classification we used, and provide recommendations to enable more detailed and accurate cross-country comparisons of healthcare provision. METHODS: We used the most recent DHS surveys between 2000 and 2012; 57 countries had data on family planning and delivery care providers and 47 countries had data on antenatal care. Every possible response option across the 57 countries was listed and categorised. We then developed a classification to group provider response options according to two key dimensions: clinical nature and profit motive. RESULTS: We classified the different types of maternal and reproductive healthcare providers, and the individuals providing care. Documented challenges encountered during this process were limitations inherent in household survey data based on respondents' self-report; conflation of response options in the questionnaire or at the data processing stage; category errors of the place vs. professional for delivery; inability to determine whether care received at home is from the public or private sector; a large number of negligible response options; inconsistencies in coding and analysis of data sets; and the use of inconsistent headings. CONCLUSIONS: To improve clarity, we recommend addressing issues such as conflation of response options, data on public vs. private provider, inconsistent coding and obtaining metadata. More systematic and standardised collection of data would aid international comparisons of progress towards improved financial protection, and allow us to better characterise the incentives and commercial nature of different providers.

4.
Geophys Res Lett ; 42(5): 1554-1559, 2015 Mar 16.
Artículo en Inglés | MEDLINE | ID: mdl-26074651

RESUMEN

It has recently been argued that single-model seasonal forecast ensembles are overdispersive, implying that the real world is more predictable than indicated by estimates of so-called perfect model predictability, particularly over the North Atlantic. However, such estimates are based on relatively short forecast data sets comprising just 20 years of seasonal predictions. Here we study longer 40 year seasonal forecast data sets from multimodel seasonal forecast ensemble projects and show that sampling uncertainty due to the length of the hindcast periods is large. The skill of forecasting the North Atlantic Oscillation during winter varies within the 40 year data sets with high levels of skill found for some subperiods. It is demonstrated that while 20 year estimates of seasonal reliability can show evidence of overdispersive behavior, the 40 year estimates are more stable and show no evidence of overdispersion. Instead, the predominant feature on these longer time scales is underdispersion, particularly in the tropics. KEY POINTS: Predictions can appear overdispersive due to hindcast length sampling errorLonger hindcasts are more robust and underdispersive, especially in the tropicsTwenty hindcasts are an inadequate sample size to assess seasonal forecast skill.

5.
J Vis ; 15(16): 5, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26641948

RESUMEN

To shed light on the perceptual basis of the color white, we measured settings of unique white in a dark surround. We find that settings reliably show more variability in an oblique (blue-yellow) direction in color space than along the cardinal axes of the cone-opponent mechanisms. This is against the idea that white perception arises at the null point of the cone-opponent mechanisms, but one alternative possibility is that it occurs through calibration to the visual environment. We found that the locus of maximum variability in settings lies close to the locus of natural daylights, suggesting that variability may result from uncertainty about the color of the illuminant. We tested this by manipulating uncertainty. First, we altered the extent to which the task was absolute (requiring knowledge of the illumination) or relative. We found no clear effect of this factor on the reduction in sensitivity in the blue-yellow direction. Second, we provided a white surround as a cue to the illumination or left the surround dark. Sensitivity was selectively worse in the blue-yellow direction when the surround was black than when it was white. Our results can be functionally related to the statistics of natural images, where a greater blue-yellow dispersion is characteristic of both reflectances (where anisotropy is weak) and illuminants (where it is very pronounced). Mechanistically, the results could suggest a neural signal responsive to deviations from the blue-yellow locus or an adaptively matched range of contrast response functions for signals that encode different directions in color space.


Asunto(s)
Percepción de Color/fisiología , Células Fotorreceptoras Retinianas Conos/fisiología , Color , Femenino , Humanos , Luz , Masculino , Estimulación Luminosa/métodos , Adulto Joven
6.
J Physiol ; 592(24): 5507-27, 2014 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-25362150

RESUMEN

We examined the hypotheses that: (1) during incremental exercise and recovery following 4-6 days at high altitude (HA) global cerebral blood flow (gCBF) increases to preserve cerebral oxygen delivery (CDO2) in excess of that required by an increasing cerebral metabolic rate of oxygen ( CM RO2); (2) the trans-cerebral exchange of oxygen vs. carbohydrates (OCI; carbohydrates = glucose + ½lactate) would be similar during exercise and recovery at HA and sea level (SL). Global CBF, intra-cranial arterial blood velocities, extra-cranial blood flows, and arterial-jugular venous substrate differences were measured during progressive steady-state exercise (20, 40, 60, 80, 100% maximum workload (Wmax)) and through 30 min of recovery. Measurements (n = 8) were made at SL and following partial acclimatization to 5050 m. At HA, absolute Wmax was reduced by ∼50%. During submaximal exercise workloads (20-60% Wmax), despite an elevated absolute gCBF (∼20%, P < 0.05) the relative increases in gCBF were not different at HA and SL. In contrast, gCBF was elevated at HA compared with SL during 80 and 100% Wmax and recovery. Notwithstanding a maintained CDO2 and elevated absolute CM RO2 at HA compared with SL, the relative increase in CM RO2 was similar during 20-80% Wmax but half that of the SL response (i.e. 17 vs. 27%; P < 0.05 vs. SL) at 100% Wmax. The OCI was reduced at HA compared with SL during 20, 40, and 60% Wmax but comparable at 80 and 100% Wmax. At HA, OCI returned almost immediately to baseline values during recovery, whereas at SL it remained below baseline. In conclusion, the elevations in gCBF during exercise and recovery at HA serve to maintain CDO2. Despite adequate CDO2 at HA the brain appears to increase non-oxidative metabolism during exercise and recovery.


Asunto(s)
Altitud , Encéfalo/metabolismo , Metabolismo de los Hidratos de Carbono , Circulación Cerebrovascular , Ejercicio Físico , Consumo de Oxígeno , Adulto , Encéfalo/irrigación sanguínea , Encéfalo/fisiología , Humanos , Masculino
7.
J Vis ; 14(13): 19, 2014 Nov 20.
Artículo en Inglés | MEDLINE | ID: mdl-25413625

RESUMEN

For anomalous trichromats, threshold contrasts for color differences captured by the L and M cones and their anomalous analogs are much higher than for normal trichromats. The greater spectral overlap of the cone sensitivities reduces chromatic contrast both at and above threshold. But above threshold, adaptively nonlinear processing might compensate for the chromatically impoverished photoreceptor inputs. Ratios of sensitivity for threshold variations and for color appearance along the two cardinal axes of MacLeod-Boynton chromaticity space were calculated for three groups: normals (N = 15), deuteranomals (N = 9), and protanomals (N = 5). Using a four-alternative forced choice (4AFC) task, threshold sensitivity was measured in four color-directions along the two cardinal axes. For the same participants, we reconstructed perceptual color spaces for the positions of 25 hues using multidimensional scaling (MDS). From the reconstructed color spaces we extracted "color difference ratios," defined as ratios for the size of perceived color differences along the L/(L + M) axis relative to those along the S/(L + M) axis, analogous to "sensitivity ratios" extracted from the 4AFC task. In the 4AFC task, sensitivity ratios were 38% of normal for deuteranomals and 19% of normal for protanomals. Yet, in the MDS results, color difference ratios were 86% of normal for deuteranomals and 67% of normal for protanomals. Thus, the contraction along the L/(L + M) axis shown in the perceptual color spaces of anomalous trichromats is far smaller than predicted by their reduced sensitivity, suggesting that an adaptive adjustment of postreceptoral gain may magnify the cone signals of anomalous trichromats to exploit the range of available postreceptoral neural signals.


Asunto(s)
Defectos de la Visión Cromática/fisiopatología , Visión de Colores/fisiología , Sensibilidad de Contraste/fisiología , Células Fotorreceptoras Retinianas Conos/fisiología , Adulto , Conducta de Elección , Pruebas de Percepción de Colores/métodos , Femenino , Humanos , Masculino , Umbral Sensorial/fisiología , Adulto Joven
8.
Anaesthesia ; 68(12): 1220-3, 2013 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-23992483

RESUMEN

Pulse oximetry is a standard of care during anaesthesia in high-income countries. However, 70% of operating environments in low- and middle-income countries have no pulse oximeter. The 'Lifebox' oximetry project set out to bridge this gap with an inexpensive oximeter meeting CE (European Conformity) and ISO (International Organization for Standardization) standards. To date, there are no performance-specific accuracy data on this instrument. The aim of this study was to establish whether the Lifebox pulse oximeter provides clinically reliable haemoglobin oxygen saturation (Sp O2 ) readings meeting USA Food and Drug Administration 510(k) standards. Using healthy volunteers, inspired oxygen fraction was adjusted to produce arterial haemoglobin oxygen saturation (Sa O2 ) readings between 71% and 100% measured with a multi-wavelength oximeter. Lifebox accuracy was expressed using bias (Sp O2 - Sa O2 ), precision (SD of the bias) and the root mean square error (Arms). Simultaneous readings of Sa O2 and Sp O2 in 57 subjects showed a mean (SD) bias of -0.41% (2.28%) and Arms 2.31%. The Lifebox pulse oximeter meets current USA Food and Drug Administration standards for accuracy, thus representing an inexpensive solution for patient monitoring without compromising standards.


Asunto(s)
Hipoxia/diagnóstico , Monitoreo Fisiológico/instrumentación , Monitoreo Fisiológico/normas , Oximetría/instrumentación , Oximetría/normas , Adulto , Femenino , Voluntarios Sanos , Humanos , Hipoxia/sangre , Masculino , Monitoreo Fisiológico/métodos , Oximetría/métodos , Reproducibilidad de los Resultados
9.
J Physiol ; 590(14): 3261-75, 2012 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-22495584

RESUMEN

Despite the importance of blood flow on brainstem control of respiratory and autonomic function, little is known about regional cerebral blood flow (CBF) during changes in arterial blood gases.We quantified: (1) anterior and posterior CBF and reactivity through a wide range of steady-state changes in the partial pressures of CO2 (PaCO2) and O2 (PaO2) in arterial blood, and (2) determined if the internal carotid artery (ICA) and vertebral artery (VA) change diameter through the same range.We used near-concurrent vascular ultrasound measures of flow through the ICA and VA, and blood velocity in their downstream arteries (the middle (MCA) and posterior (PCA) cerebral arteries). Part A (n =16) examined iso-oxic changes in PaCO2, consisting of three hypocapnic stages (PaCO2 =∼15, ∼20 and ∼30 mmHg) and four hypercapnic stages (PaCO2 =∼50, ∼55, ∼60 and ∼65 mmHg). In Part B (n =10), during isocapnia, PaO2 was decreased to ∼60, ∼44, and ∼35 mmHg and increased to ∼320 mmHg and ∼430 mmHg. Stages lasted ∼15 min. Intra-arterial pressure was measured continuously; arterial blood gases were sampled at the end of each stage. There were three principal findings. (1) Regional reactivity: the VA reactivity to hypocapnia was larger than the ICA, MCA and PCA; hypercapnic reactivity was similar.With profound hypoxia (35 mmHg) the relative increase in VA flow was 50% greater than the other vessels. (2) Neck vessel diameters: changes in diameter (∼25%) of the ICA was positively related to changes in PaCO2 (R2, 0.63±0.26; P<0.05); VA diameter was unaltered in response to changed PaCO2 but yielded a diameter increase of +9% with severe hypoxia. (3) Intra- vs. extra-cerebral measures: MCA and PCA blood velocities yielded smaller reactivities and estimates of flow than VA and ICA flow. The findings respectively indicate: (1) disparate blood flow regulation to the brainstem and cortex; (2) cerebrovascular resistance is not solely modulated at the level of the arteriolar pial vessels; and (3) transcranial Doppler ultrasound may underestimate measurements of CBF during extreme hypoxia and/or hypercapnia.


Asunto(s)
Encéfalo/irrigación sanguínea , Hipercapnia/sangre , Hipocapnia/sangre , Hipoxia/sangre , Adulto , Velocidad del Flujo Sanguíneo/fisiología , Análisis de los Gases de la Sangre , Arteria Carótida Interna/diagnóstico por imagen , Arterias Cerebrales/diagnóstico por imagen , Femenino , Humanos , Hipercapnia/diagnóstico por imagen , Hipocapnia/diagnóstico por imagen , Hipoxia/diagnóstico por imagen , Masculino , Flujo Sanguíneo Regional/fisiología , Ultrasonografía Doppler Transcraneal , Vasoconstricción/fisiología , Vasodilatación/fisiología , Arteria Vertebral/diagnóstico por imagen
10.
Int J Androl ; 34(6 Pt 2): e578-86, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21631528

RESUMEN

Experimental animal studies show that measurement of anogenital distance (AGD) and/or penis length may provide lifelong 'read-outs' of foetal androgen exposure during the masculinization programming window (MPW). However, variation in postnatal androgen exposure may complicate interpretation of such measurements. This is important to clarify if such measurements are to be applied to humans. The present aim was to evaluate effects of prenatal and/or postnatal manipulation of androgen production/action on growth of AGD and the penis in rats. Pregnant rats were treated daily before (e13.5-e21.5) and after birth (postnatal days 1-15) with either vehicle, 500 mg/kg di(n-butyl) phthalate (DBP) or 100 mg/kg flutamide (postnatal only) in prenatal + postnatal treatment combinations (N = 6 treatment combinations); DBP impairs androgen production whereas flutamide impairs androgen action. Male offspring were killed on postnatal day 8 (prepuberty), 25 (early puberty) or 90 (adulthood) when AGD was measured, the penis dissected out and its weight and length measured; plasma testosterone and ventral prostate weight were measured at day 90 to assess endogenous androgen exposure. In controls, penis length, girth and AGD increased 2.2-, 5.3-and 5.9-fold respectively from day 8 to day 90. Significant inhibition of penis growth and final length and girth was induced by treatments that inhibited postnatal androgen action. Conversely, growth and ultimate (adult) AGD was inhibited by prenatal inhibition of androgen production whereas postnatal androgen inhibition had negligible effect. Nevertheless, AGD and penis length were highly correlated at every age (R(2) > 0.33; p < 0.0001). However, altered endogenous androgen exposure may confound interpretation of changes in adults exposed prenatally/postnatally to DBP/flutamide. We conclude that AGD provides a lifelong guide to prenatal androgen exposure (in the MPW) whereas penis size reflects both prenatal + postnatal androgen exposure. At the group treatment level, prepubertal measurement of either AGD or penis size accurately predicts their size in adulthood.


Asunto(s)
Canal Anal/crecimiento & desarrollo , Andrógenos/fisiología , Pene/crecimiento & desarrollo , Maduración Sexual , Animales , Femenino , Masculino , Embarazo , Ratas , Ratas Wistar
11.
Health Policy Plan ; 36(6): 881-890, 2021 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-33963387

RESUMEN

The global expansion of HIV testing, prevention and treatment services is necessary to achieve HIV epidemic control and promote individual and population health benefits for people living with HIV (PLHIV) in sub-Saharan Africa. Community-based health workers (CHWs) could play a key role in supporting implementation at scale. In the HPTN 071 (PopART) trial in Zambia and South Africa, a cadre of 737 study-specific CHWs, working closely with government-employed CHW, were deployed to deliver a 'universal' door-to-door HIV prevention package, including an annual offer of HIV testing and referral services for all households in 14 study communities. We conducted a process evaluation using qualitative and quantitative data collected during the trial (2013-2018) to document the implementation of the CHW intervention in practice. We focused on the recruitment, retention, training and support of CHWs, as they delivered study-specific services. We then used these descriptions to: (i) analyse the fidelity to design of the delivery of the intervention package, and (ii) suggest key insights for the transferability of the intervention to other settings. The data included baseline quantitative data collected with the study-specific CHWs (2014-2018); and qualitative data from key informant interviews with study management (n = 91), observations of CHW training events (n = 12) and annual observations of and group discussions (GD) with intervention staff (n = 68). We show that it was feasible for newly recruited CHWs to implement the PopART intervention with good fidelity, supporting the interpretation of the trial outcome findings. This was despite some challenges in managing service quality and CHW retention in the early years of the programme. We suggest that by prioritizing the adoption of key elements of the in-home HIV services delivery intervention model-including training, emotional support to workers, monitoring and appropriate remuneration for CHWs-these services could be successfully transferred to new settings.


Asunto(s)
Infecciones por VIH , Prueba de VIH , Agentes Comunitarios de Salud , Infecciones por VIH/diagnóstico , Infecciones por VIH/prevención & control , Humanos , Sudáfrica , Zambia
12.
Int J Androl ; 33(2): 279-87, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20002220

RESUMEN

We have shown previously that deficient androgen action within a masculinization programming window (MPW; e15.5-e18.5 in rats) is important in the origin of male reproductive disorders and in programming male reproductive organ size, but that androgen action postnatally may be important to achieve this size. To further investigate importance of the MPW, we used two rat models, in which foetal androgen production or action was impaired during the MPW by exposing in utero to either di(n-butyl) phthalate (DBP) or to flutamide. Reduced anogenital distance (AGD) was used as a monitor of androgen production/action during the MPW. Offspring were evaluated in early puberty (Pnd25) to establish if reproductive organ size was altered. The testes, penis, ventral prostate (VP) and seminal vesicles (SV) were weighed and penis length measured. Both DBP and flutamide exposure in the MPW significantly reduced penis, VP and SV size along with AGD at Pnd25; AGD and organ size were highly correlated. In DBP-, but not flutamide-, exposed animals, testis weight was also reduced and correlated with AGD. Intratesticular testosterone was also measured in control and DBP-exposed males during (e17.5) or after (e21.5) the MPW and related to AGD at e21.5. To evaluate the importance of postnatal androgen action in reproductive organ growth, the effect of combinations of prenatal and postnatal maternal treatments on AGD and penis size at Pnd25 was evaluated. In prenatally DBP-exposed animals, further postnatal exposure to either DBP or flutamide significantly reduced AGD and penis size in comparison with prenatal DBP exposure alone. In comparison, rats exposed postnatally to testosterone propionate after prenatal vehicle-exposure showed considerable increase in these parameters vs. controls. In conclusion, we show that the size of all male reproductive organs is programmed by androgen exposure in the MPW, but that growth towards this size is dependent on androgen action postnatally.


Asunto(s)
Andrógenos/fisiología , Dibutil Ftalato/toxicidad , Genitales Masculinos/crecimiento & desarrollo , Antagonistas de Andrógenos/farmacología , Andrógenos/farmacología , Animales , Animales Recién Nacidos , Femenino , Flutamida/farmacología , Genitales Masculinos/efectos de los fármacos , Disgenesia Gonadal/etiología , Masculino , Tamaño de los Órganos/efectos de los fármacos , Pene/efectos de los fármacos , Pene/crecimiento & desarrollo , Embarazo , Efectos Tardíos de la Exposición Prenatal , Próstata/efectos de los fármacos , Próstata/crecimiento & desarrollo , Ratas , Ratas Wistar , Vesículas Seminales/efectos de los fármacos , Vesículas Seminales/crecimiento & desarrollo , Diferenciación Sexual , Enfermedades Testiculares/etiología , Testículo/efectos de los fármacos , Testículo/crecimiento & desarrollo , Testículo/patología , Testosterona/metabolismo , Propionato de Testosterona/farmacología
13.
Science ; 185(4157): 1171-2, 1974 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-4415643

RESUMEN

Afterimages fade against any unchanging background but generally reappear if the background changes suddenly. Under some conditions, however, a change of background color fails to revive a faded afterimage. This happens only if the interchanged backgrounds equally stimulate the rod receptors. It follows that afterimages seen under these conditions are generated by rods.


Asunto(s)
Postimagen , Percepción de Color , Células Fotorreceptoras/fisiología , Umbral Diferencial , Humanos , Luz , Modelos Biológicos , Estimulación Luminosa , Pigmentos Retinianos/fisiología , Factores de Tiempo
14.
Science ; 195(4279): 698-9, 1977 Feb 18.
Artículo en Inglés | MEDLINE | ID: mdl-841308

RESUMEN

It is widely believed that human rods cannot detect rapid flicker. With rod-isolation techniques, however, light-adapted rods detect flicker frequencies as high as 28 hertz, and the function relating rod critical flicker frequency to stimulus intensity contains two distinct branches. Human rod vision may, therefore, depend on two independent mechanisms.


Asunto(s)
Fusión de Flicker/fisiología , Células Fotorreceptoras/fisiología , Adaptación a la Oscuridad , Humanos
15.
Science ; 172(3983): 570-2, 1971 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-5555077

RESUMEN

Anoxic ventricular muscle maintained a normal resting potenitial despite a large loss of potassium. The resting potential was separated into two components: one that depended on the potassium distribution, and one that depended on the activity of an electrogenic sodium pump.


Asunto(s)
Potenciales de Acción , Hipoxia , Músculos Papilares/fisiología , Sodio/fisiología , Animales , Transferencia de Energía , Cobayas , Ventrículos Cardíacos , Potasio/fisiología , Temperatura
17.
J Ayub Med Coll Abbottabad ; 20(1): 136-7, 2008.
Artículo en Inglés | MEDLINE | ID: mdl-19024208

RESUMEN

A 45-year-old female with a background of poorly differentiated ovarian adenocarcinoma treated with bilateral salpingo-oophorectomy presented with one week history of nausea, vomiting and decreased urine output. On examination, she was mildly dehydrated but haemodynamically stable. Abdominal examination revealed tender swelling in upper abdomen. Biochemistry revealed that she had acute renal failure and interestingly the acute renal failure was out of proportion to the degree of dehydration. Abdominal ultrasound showed marked distension of the stomach without any evidence of renal tract obstruction. She was aggressively treated with volume replacement and careful monitoring of input and output. She responded very well to fluid replacement and her renal failure resolved within four days of treatment. This case illustrates a case of acute renal failure secondary to gastroparesis which resolved after treatment of renal failure. Patients with chronic renal failure are prone to develop gastroparesis but it is extremely rare to have gastric stasis following acute renal failure. This case also illustrates the importance of aggressive treatment of a reversible but potentially fatal medical condition which could have been easily overlooked in view of patient's poorly differentiated ovarian cancer.


Asunto(s)
Lesión Renal Aguda/complicaciones , Gastroparesia/etiología , Lesión Renal Aguda/fisiopatología , Adenocarcinoma/fisiopatología , Femenino , Fluidoterapia , Gastroparesia/diagnóstico , Gastroparesia/terapia , Humanos , Persona de Mediana Edad , Neoplasias Ováricas/fisiopatología , Factores de Riesgo
18.
Curr Biol ; 7(11): 844-9, 1997 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-9382808

RESUMEN

BACKGROUND: The perceived color at each point in a visual scene depends on the relationship between light signals from that point, and light signals from surrounding areas of the scene. In the well known phenomenon of simultaneous color contrast, changing the overall brightness or hue of an object's surround induces a complementary shift in the perceived brightness or hue of the object's color. Color contrast is thought to contribute to color constancy with changes in illumination. RESULTS: We report a new type of simultaneous color contrast, in which changing only the variance (i.e. contrasts and saturations), but not the mean, of colors in a test spot's surround induces a complementary shift in the perceived contrast and saturation of the test spot's color. Objects appear much more vivid and richly colored against low-contrast, gray surrounds than against high-contrast, multicolored surrounds. CONCLUSIONS: Color appearance depends not just on the mean color of the surround, but also on the distribution of surround colors about the mean. This novel form of simultaneous color contrast is inconsistent with a variety of models of color appearance, including those based on sensitivity regulation at the receptor level, and those in which the effects of complex surrounds on color appearance can be reduced to adaptation to the illuminant or induction from a homogeneous 'equivalent surround'. It tends to normalize the gamut of perceived colors in each visual scene and may also contribute to color constancy under viewing conditions that affect contrast.


Asunto(s)
Pruebas de Percepción de Colores , Percepción de Color/fisiología , Humanos , Procesamiento de Imagen Asistido por Computador , Luz , Estimulación Luminosa , Células Fotorreceptoras/fisiología , Distribución Aleatoria , Grabación en Video
19.
Mol Cell Biol ; 18(8): 4433-43, 1998 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-9671453

RESUMEN

Nonmethylated CpG islands are generally located at the 5' ends of genes, but a CpG island in the mouse major histocompatibility complex class II I-Abeta gene is remote from the promoter and covers exon 2. We have found that this CpG island includes a novel intronic promoter that is active in embryonic and germ cells. The resulting transcript potentially encodes a severely truncated protein which would lack the signal peptide and external beta1 domains. The functional significance of the internal CpG island may be to facilitate gene conversion, thereby sustaining the high level of polymorphism seen at exon 2. Deletions of the I-Abeta CpG island promoter reduce transcription and frequently lead to methylation of the CpG island in a transgenic mouse assay. These and other results support the idea that all CpG islands arise at promoters that are active in early embryonic cells.


Asunto(s)
Islas de CpG , Antígenos de Histocompatibilidad Clase II/genética , Regiones Promotoras Genéticas , Animales , Secuencia de Bases , Células Cultivadas , ADN , Metilación de ADN , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos CBA , Ratones Transgénicos , Datos de Secuencia Molecular , Testículo/metabolismo
20.
Clin Transl Sci ; 10(5): 351-359, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-28689370

RESUMEN

Intra-Target Microdosing (ITM) is a novel drug development approach aimed at increasing the efficiency of first-in-human (FIH) testing of new molecular entities (NMEs). ITM combines intra-target drug delivery and "microdosing," the subpharmacological systemic exposure. We hypothesized that when the target tissue is small (about 1/100th of total body mass), ITM can lead to target therapeutic-level exposure with minimal (microdose) systemic exposure. Each of five healthy male volunteers received insulin microdose into the radial artery or full therapeutic dose intravenously in separate visits. Insulin and glucose levels were similar between systemic administration and ITM administration in the ipsilateral hand, and glucose levels demonstrated a reduction in the ipsilateral hand but not in the contralateral hand. Positron emission tomography (PET) imaging of 18 F-fluorodeoxyglucose (FDG) uptake demonstrated differences between the ipsilateral and contralateral arms. The procedures were safe and well-tolerated. Results are consistent with ITM proof-of-concept (POC) and demonstrate the ethical, regulatory, and logistical feasibility of the approach.


Asunto(s)
Descubrimiento de Drogas , Insulina/administración & dosificación , Adulto , Glucemia/metabolismo , Relación Dosis-Respuesta a Droga , Estudios de Factibilidad , Humanos , Insulina/sangre , Masculino , Tomografía de Emisión de Positrones , Adulto Joven
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