Seasonal variation in net ecosystem CO2 exchange of a Brazilian seasonally dry tropical forest.

Forest ecosystems sequester large amounts of atmospheric CO2, and the contribution from seasonally dry tropical forests is not negligible. Thus, the objective of this study was to quantify and evaluate the seasonal and annual patterns of CO2 exchanges in the Caatinga biome, as well as to evaluate the ecosystem condition as carbon sink or source during years. In addition, we analyzed the climatic factors that control the seasonal variability of gross primary production (GPP), ecosystem respiration (Reco) and net ecosystem CO2 exchange (NEE). Results showed that the dynamics of the components of the CO2 fluxes varied depending on the magnitude and distribution of rainfall and, as a consequence, on the variability of the vegetation state. Annual cumulative NEE was significantly higher (p < 0.01) in 2014 (-169.0 g C m-2) when compared to 2015 (-145.0 g C m-2) and annual NEP/GPP ratio was 0.41 in 2014 and 0.43 in 2015. Global radiation, air and soil temperature were the main factors associated with the diurnal variability of carbon fluxes. Even during the dry season, the NEE was at equilibrium and the Caatinga acted as an atmospheric carbon sink during the years 2014 and 2015.

Cigarette toxicity triggers Leber's hereditary optic neuropathy by affecting mtDNA copy number, oxidative phosphorylation and ROS detoxification pathways.

Leber's hereditary optic neuropathy (LHON), the most frequent mitochondrial disease, is associated with mitochondrial DNA (mtDNA) point mutations affecting Complex I subunits, usually homoplasmic. This blinding disorder is characterized by incomplete penetrance, possibly related to several genetic modifying factors. We recently reported that increased mitochondrial biogenesis in unaffected mutation carriers is a compensatory mechanism, which reduces penetrance. Also, environmental factors such as cigarette smoking have been implicated as disease triggers. To investigate this issue further, we first assessed the relationship between cigarette smoke and mtDNA copy number in blood cells from large cohorts of LHON families, finding that smoking was significantly associated with the lowest mtDNA content in affected individuals. To unwrap the mechanism of tobacco toxicity in LHON, we exposed fibroblasts from affected individuals, unaffected mutation carriers and controls to cigarette smoke condensate (CSC). CSC decreased mtDNA copy number in all cells; moreover, it caused significant reduction of ATP level only in mutated cells including carriers. This implies that the bioenergetic compensation in carriers is hampered by exposure to smoke derivatives. We also observed that in untreated cells the level of carbonylated proteins was highest in affected individuals, whereas the level of several detoxifying enzymes was highest in carriers. Thus, carriers are particularly successful in reactive oxygen species (ROS) scavenging capacity. After CSC exposure, the amount of detoxifying enzymes increased in all cells, but carbonylated proteins increased only in LHON mutant cells, mostly from affected individuals. All considered, it appears that exposure to smoke derivatives has a more deleterious effect in affected individuals, whereas carriers are the most efficient in mitigating ROS rather than recovering bioenergetics. Therefore, the identification of genetic modifiers that modulate LHON penetrance must take into account also the exposure to environmental triggers such as tobacco smoke.

Electroretinography in dogs using a fiber electrode prototype.

We compared two electroretinography (ERG) electrodes in dogs using ERG standards of the International Society for Clinical Electrophysiology of Vision (ISCEV). Ten healthy Yorkshire terrier dogs (mean age, 2.80 ± 1.42 years; 6 females) weighing 5.20 ± 1.56 kg were evaluated using an ERG system for veterinary use. Dark- and light-adapted ERG responses were recorded using an ERG-Jet electrode and a fiber electrode prototype. The examinations were performed during 2 visits, 3 weeks apart. Both electrodes (ERG-Jet or fiber prototype) were used on each animal and the first eye to be recorded (OD × OS) was selected randomly. Three weeks later the examination was repeated on the same animal switching the type of electrode to be used that day and the first eye to be examined. The magnitude and waveform quality obtained with the two electrode types were similar for all ERG responses. ERG amplitudes and implicit times obtained from dogs using the fiber electrode prototype were comparable to those obtained with the ERG-Jet electrode for rod, maximal rod-cone summed, cone, and 30-Hz flicker responses. The fiber electrode prototype is a low-cost device, available as an alternative instrument for clinical veterinary ERG recording for retinal function assessment.

Electroretinography in dogs using a fiber electrode prototype

We compared two electroretinography (ERG) electrodes in dogs using ERG standards of the International Society for Clinical Electrophysiology of Vision (ISCEV). Ten healthy Yorkshire terrier dogs (mean age, 2.80 ± 1.42 years; 6 females) weighing 5.20 ± 1.56 kg were evaluated using an ERG system for veterinary use. Dark- and light-adapted ERG responses were recorded using an ERG-Jet electrode and a fiber electrode prototype. The examinations were performed during 2 visits, 3 weeks apart. Both electrodes (ERG-Jet or fiber prototype) were used on each animal and the first eye to be recorded (OD × OS) was selected randomly. Three weeks later the examination was repeated on the same animal switching the type of electrode to be used that day and the first eye to be examined. The magnitude and waveform quality obtained with the two electrode types were similar for all ERG responses. ERG amplitudes and implicit times obtained from dogs using the fiber electrode prototype were comparable to those obtained with the ERG-Jet electrode for rod, maximal rod-cone summed, cone, and 30-Hz flicker responses. The fiber electrode prototype is a low-cost device, available as an alternative instrument for clinical veterinary ERG recording for retinal function assessment.

Psychophysical analysis of contrast processing segregated into magnocellular and parvocellular systems in asymptomatic carriers of 11778 Leber's hereditary optic neuropathy.

We examined achromatic contrast discrimination in asymptomatic carriers of 11778 Leber's hereditary optic neuropathy (LHON 18 controls) and 18 age-match were also tested. To evaluate magnocellular (MC) and Parvocellular (PC) contrast discrimination, we used a version of Pokorny and Smith's (1997) pulsed/steady-pedestal paradigms (PPP/SPP) thought to be detected via PC and MC pathways, respectively. A luminance pedestal (four 1 degree x 1 degree squares) was presented on a 12 cd/m2 surround. The luminance of one of the squares (trial square, TS) was randomly incremented for either 17 or 133 ms. Observers had to detect the TS, in a forced-choice task, at each duration, for three pedestal levels: 7, 12, 19 cd/m2. In the SPP, the pedestal was fixed, and the TS was modulated. For the PPP, all four pedestal squares pulsed for 17 or 133 ms, and the TS was simultaneously incremented or decremented. We found that contrast discrimination thresholds of LHON carriers were significantly higher than controls' in the condition with the highest luminance of both paradigms, implying impaired contrast processing with no evidence of differential sensitivity losses between the two systems. Carriers' thresholds manifested significantly longer temporal integration than controls in the SPP, consistent with slowed MC responses. The SPP and PPP paradigms can identify contrast and temporal processing deficits in asymptomatic LHON carriers, and thus provide an additional tool for early detection and characterization of the disease.

Colour vision defects in asymptomatic carriers of the Leber's hereditary optic neuropathy (LHON) mtDNA 11778 mutation from a large Brazilian LHON pedigree: a case-control study.

AIMS: To determine if asymptomatic carriers from a previously identified large pedigree of the Leber's hereditary optic neuropathy (LHON) 11778 mtDNA mutation have colour vision deficits. METHODS: As part of a comprehensive analysis of over 200 members of a large Brazilian LHON pedigree spanning seven generations, colour vision tests were obtained from 91 members. Colour vision was tested one eye at a time using the Farnsworth-Munsell 100 (FM-100) hue colour vision test. The test was administered under uniform conditions, taking into account: ambient light levels, daylight colour temperature of 6700 kelvin, and neutral uniform background. Tests were scored using the FM-100 MS-Excel computer scoring program. Defects were determined and categorised as tritan, deutan, or protan. Categorisation of each dyschromatopsia was based on review of demonstrated axis computer generated plots and age adjusted error scores which coincided with Verriest 95% confidence intervals. Only the axis with the greatest magnitude error score was used to classify the defect. 55 of the 91 test subjects were LHON mtDNA 11778 J haplotype mutation carriers, proved by mtDNA analysis. The remaining 36 subjects were age matched non-blood relatives (off pedigree), who served as controls. RESULTS: 27 of 55 carriers (49.10%) were shown to have colour vision defects in one or both eyes. 13 of the 27 (48%) abnormal tests in the carrier group were tritan defects and the remaining 14 (52%) were deutan defects. Nine of the 27 (33%) abnormals in the carrier group were identified as having bilateral defects. Six of these were deutan, and the remaining three were tritan dyschromatopsias. Only six of the 36 (16.66%) age matched controls were found to have any type of dyschromatopsia. Five (83.3%) of these were deutan defects. The remaining one was a tritan defect. The difference between the two groups using a chi(2) test with one degree of freedom was statistically significant with a p value less that 0.001. CONCLUSIONS: Until now, LHON has always been characterised by a sudden, devastating vision loss. Asymptomatic carriers, those without vision loss, were considered unaffected by the disease. It now appears that asymptomatic carriers of the LHON mutation are affected by colour vision defects and may manifest other subtle, yet chronic, changes.

Pupil size following dark adaptation in patients with retinitis pigmentosa

According to the equivalent light hypothesis, molecular defects in the photoreceptor lead to a continuous activation of the photoreceptor cascade in a manner equivalent to real light. The consequences in diseases such as retinitis pigmentosa (RP) are as disruptive to the cells as real light. Two forms of the equivalent light hypothesis can be distinguished: strong - mutations in rhodopsin or other cascade proteins in some forms of RP continuously excite the visual phototransduction cascade; weak - disruption of outer segments in all patients with RP eliminates circulating dark current and blocks neurotransmitter release in a manner similar to real light. Both forms of the equivalent light hypothesis predict that pupils of patients with RP will be constricted like those of normal subjects in the light. The purpose of this study was to test the equivalent light hypothesis by determining whether steady-state pupil diameter following full dark adaptation is abnormally small in any of a sample of patients with RP. Thirty-five patients with RP and 15 normal subjects were tested. Direct steady-state pupillometric measures were obtained from one eye in a full-field dome after 45 min of dark adaptation by videotaping the pupil with an infrared camera. Mean pupil diameter in the dark was comparable (t = -0.15, P = 0.88) between patients with RP (6.85 Ý 0.58 mm) and normal subjects (6.82 Ý 0.76 mm). The results of the present study are clearly counter to the prediction of the second (weaker) form of the equivalent light hypothesis

Pupil size following dark adaptation in patients with retinitis pigmentosa.

According to the equivalent light hypothesis, molecular defects in the photoreceptor lead to a continuous activation of the photoreceptor cascade in a manner equivalent to real light. The consequences in diseases such as retinitis pigmentosa (RP) are as disruptive to the cells as real light. Two forms of the equivalent light hypothesis can be distinguished: strong - mutations in rhodopsin or other cascade proteins in some forms of RP continuously excite the visual phototransduction cascade; weak - disruption of outer segments in all patients with RP eliminates circulating dark current and blocks neurotransmitter release in a manner similar to real light. Both forms of the equivalent light hypothesis predict that pupils of patients with RP will be constricted like those of normal subjects in the light. The purpose of this study was to test the equivalent light hypothesis by determining whether steady-state pupil diameter following full dark adaptation is abnormally small in any of a sample of patients with RP. Thirty-five patients with RP and 15 normal subjects were tested. Direct steady-state pupillometric measures were obtained from one eye in a full-field dome after 45 min of dark adaptation by videotaping the pupil with an infrared camera. Mean pupil diameter in the dark was comparable (t = -0.15, P = 0.88) between patients with RP (6.85 +/- 0.58 mm) and normal subjects (6.82 +/- 0.76 mm). The results of the present study are clearly counter to the prediction of the second (weaker) form of the equivalent light hypothesis.

Non-invasive monitoring of pulmonary capillary wedge pressure in heart failure.

OBJECTIVE: To evaluate the usefulness of pulsed Doppler (PD) mitral flow E wave deceleration time (EDcT) to detect and quantify changes of pulmonary capillary wedge pressure (PCWP) in patients (pt) with dilated chronic heart failure (CHF) submitted to tailored therapy. METHODS: In 14 pt with dilated cardiomyopathy (DCM) (59.4+/-10.0 years, 11 males, sinus rhythm), admitted to the ICU because of worsening CHF, serial simultaneous hemodynamic and echocardiographic studies were performed (3-5/pt; overall 49 evaluations). PD mitral flow register was used to measure EDcT and correlated with PCWP at each study. RESULTS: PCWP ranged from 36 to 3 mmHg (17.6+/-8.8) and EDcT from 271 to 52 ms (104.9+/-42.4). The correlation between EDcT and PCWP was -0.65 (PCWP=31.7-0.134EDcT). Using this equation to calculate PCWP, individual absolute values difference (identity error - IE) was 5.6+/-3.5 mmHg (0.4-14.6). In 29 cases (59.2%) IE was >5 mmHg, defined as major error. Considering EDcT percent change (delta%EDcT) and PCWP variation (deltaPCWP) in serial evaluations, we found a correlation of -0.87 (deltaPCWP=-2.83-0.19 delta%EDcT). Using this equation, the IE was 2.3+/-1.6 mmHg (0-5.2) and there were only two (6%) major errors (P<0.0001). CONCLUSIONS: In pt with DCM and advanced CHF, EDcT shows a reasonable correlation with PCWP, but when it is used to calculate PCWP the IE to hemodynamic values is often large. However, our results with EDcT percent change in serial evaluations using a first simultaneous invasive determination, suggest that this technique is reliable for monitoring PCWP and can be particularly useful for pt submitted to tailored therapy.

[Diagnosis of paradoxal and concomitant pulmonary thromboembolism with transesophageal echocardiography: a clinical case]. / Diagnóstico de tromboembolismo paradoxal e pulmonar concomitante por ecocardiografia transesofágica: um caso clínico.

There is some controversy regarding the indications for transesophageal echocardiography in patients with suspected systemic embolism. The present case report refers to a 65 year old male admitted to the hospital for ischemic acute cerebrovascular accident, which was confirmed by cerebral computerized tomography. A transthoracic echocardiogram was performed showing right atrial and ventricular dilatation. A transesophageal echocardiogram was also performed to exclude thromboembolism and clarify dilatation of the right cavities. Mild spontaneous echocontrast was present in the left atrium without images of thrombus; an interatrial septal aneurysm with patent foramen ovale was found with right to left flow; an image compatible with a very mobile, large, proximal thrombus in the main pulmonary artery was observed. A venous duplex scan was performed, demonstrating venous thrombosis in the right popliteal and femoral veins. Pulmonary arteriography showed a large thrombus in the right pulmonary branch extending to the median lobe and a smaller thrombus in the left pulmonary branch. Apparently, the patient had no predisposing factors for thromboembolism. Full-dose heparin was started followed by oral anticoagulation. An inferior vena cava filter was implanted. At hospital discharge the pulmonary thrombus had disappeared and the right cardiac cavities had returned to normal size. The interatrial aneurysm had disappeared and foramen ovale was no longer patent. After 36 months of clinical follow up on oral anticoagulation, the patient remains asymptomatic without neurological sequelae nor respiratory distress.

Visual field defects in children with congenital glaucoma.

PURPOSE: To determine visual field defects in a cohort of children with congenital glaucoma. METHODS: Monocular visual fields were measured in 24 meridians for targets V4e, I4e, I2e, and I1e, using a Goldmann perimeter in a group of 13 children between the ages of 4 and 14 years with congenital glaucoma and 10 age-matched healthy children. Localized visual field defects (eg, paracentral scotoma, nasal step, and arcuate scotoma) were determined by abnormal findings or shape of the eye in at least one of each of the targets presented. RESULTS: Visual field extent for target 12e was significantly constricted for unilateral and bilateral cases of congenital glaucoma when compared with control eyes. A post-hoc procedure (Tukey Test) showed significant differences between unilateral cases and normal control eyes, and between bilateral cases (best outcome eye) and normal control eyes. Stimuli V4e and 14e results were comparable for patients and normals. Stimulus I1e showed significantly different total extent visual field for bilateral and normal controls. Specific visual field defects were found only in bilateral cases. Paracentral scotoma was found in 1 of 12 eyes with bilateral congenital glaucoma. Nasal steps were found in 6 of 12 eyes with bilateral congenital glaucoma. Arcuate scotoma were found in 4 of 12 eyes with bilateral congenital glaucoma. CONCLUSION: Localized visual fields were found in 37.5% of eyes with congenital glaucoma. Early treatment for congenital glaucoma provided better visual field outcome.

Cardiac output quantification by Doppler echocardiography in intensive care--limitations and validation.

UNLABELLED: Cardiac output (CO) quantification is primordial to the evaluation of patients with heart failure who are on tailored therapy and under invasive hemodynamic monitoring. Doppler echocardiography can be used to access CO noninvasively, but the concordance between its results and those obtained by invasive methods in paired measurements is still controversial. To our knowledge, no previous studies have assessed the clinical relevance of Doppler echocardiography for CO serial evaluation in patients submitted to tailored therapy. AIM: To evaluate the usefulness of echo-Doppler in the assessment of CO and quantification of changes in CO, compared to thermodilution, in patients with advanced heart failure under hemodynamic monitoring to guide tailored therapy. METHODS: In 20 patients (14 male, 62 +/- 14 years old, all in sinus rhythm), with dilated cardiomyopathy and NYHA IV, admitted to the intensive care unit (ICU), CO was simultaneously determined by Doppler echocardiography (dpCO) and thermodilution (tdCO) in three serial evaluations (overall 60). The dpCO was calculated by multiplying the aortic orifice area by the velocity-time integral of aortic continuous wave Doppler flow and by the heart rate. A difference between tdCO and dpCO of more than 20% was considered a major error. RESULTS: In the overall evaluations, dpCO systematically overestimates tdCO (p = 0.026). The correlation between tdCO and dpCO was 0.81, the mean difference between measurements was 0.40 +/- 0.61 l/min (mean -2SD = -1.62 mean +2SD = 0.81) and 19 (32%) major errors occurred. No significant difference was found between CO percentual variation values assessed by both methods, with a stronger correlation (r = 0.92-p = 0.014) compared to that found for absolute values. On using the dpCO/tdCO ratio in the first evaluation to correct subsequent dpCO, the correlation was fairly good (r = 0.96-p = 0.0002 versus corrected dpCO). The mean difference between paired measurements was significantly lower (0.12 +/- 0.28 l/min-mean 2SD = -0.44 mean +2SD = 0.67), and there were no errors. CONCLUSIONS: CO estimated by Doppler echocardiography has a good correlation with thermodilution although with a weak concordance between paired results in patients with dilated cardiomyopathy and advanced heart failure admitted to the ICU for tailored therapy. Our results with dpCO percentual change in repeated evaluations and with corrected dpCO value after a single simultaneous invasive determination suggest that Doppler echocardiography is a valid method for clinical purposes, allowing us to propose a reduction in the time period of invasive hemodynamic monitoring.

[The semiquantitative evaluation of systemic vascular resistances in heart failure via an analysis of Doppler aortic flow]. / Avaliação semiquantitativa das resistências vasculares sistémicas na insuficiência cardíaca a partir da análise do fluxo Doppler aórtico.

UNLABELLED: In patients with advanced heart failure (HF) submitted to tailored therapy, monitoring of systemic vascular resistance (SVR) is essential to establish an adequate hemodynamic response, being one of the end-points to achieve SVR < 18 Wood U (WU). PURPOSE: To correlate SVR value with parameters derived from the analysis of echo-Doppler aortic flow in patients with HF on tailored therapy, in order to allow a non-invasive semiquantitative evaluation of this hemodynamic end-point. METHODS: In 13 patients with dilated cardiomyopathy (eight idiopathic, five ischemic) and advanced HF (mean age 60 +/- 10 years, 10 male, all in sinus rhythm, NYHA class IV), admitted in the ICU and submitted to tailored therapy, serial simultaneous hemodynamic and echocardiographic studies were performed (2 to 5 per patient, overall 43 evaluations). The following parameters derived from the analysis of continuous wave aortic Doppler flow were analysed: peak velocity, acceleration, deacceleration and ejection times, systolic time intervals ratio, mean acceleration, mean deacceleration, acceleration, deacceleration and overall systolic flow velocity time integrals. RESULTS: SVR ranged from 10.4 to 41.9 WU (mean = 21.7, SD = 6.9). A significant correlation was found only with mean deacceleration (MnDc)-r = -0.60. MnDc ranged from 362 to 1162 cm/s2 (mean = 667, SD = 188) and proved to be independent from heart rate, systolic, diastolic and mean blood pressure, capillary wedge pressure, cardiac output, cardiac index and ejection volume. MnDc < 700 cm.s2 occurred in 25/28 evaluations with SVR > 18 WU and only in 3/15 evaluations with SVR < 18 WU-p = 0.00003. A MnDc value < 700 cm.s2 showed sensitivity = 89%, specificity = 80%, and predictive value = 89% for SVR > 18 WU (Kappa index = 0.693). CONCLUSION: Mean deacceleration of aortic continuous wave flow is reliable for semiquantitative evaluation of systemic vascular resistance and can be particularly useful for patients with advanced heart failure submitted to tailored therapy.

[The sinus venosus type of interatrial communication: its diagnosis by transesophageal echocardiography]. / Comunicação interauricular tipo sinus venosus: diagnóstico por ecocardiografia transesofágica.

Transthoracic echocardiography has important limitations in the diagnosis of sinus venosus atrial septal defects in adults because of the posterior location of the defect. We review the role of transesophageal echocardiography in the diagnosis of this congenital heart disease in nine patients, as well as in the identification of associated abnormal pulmonary venous connections.

[A pseudoaneurysm of the mitral-aortic intervalvular fibrosis after aortic valve replacement]. / Pseudoaneurisma da fibrosa intervalvular mitro-aórtica após substituição valvular aórtica.

A 58-year-old male underwent a transesophageal echocardiogram for suspected aortic valve infective endocarditis, four years after surgery. The examination, performed with a multiplane probe, showed a pulsatile (systolic expansion) echo-free cavity in the intervalvular mitral-aortic region, communicating with the left ventricle outflow tract, with no signs of rupture to the left atrium or the aorta. These findings meet the criteria for the diagnosis of pseudoaneurysm of the mitral-aortic intervalvular fibrosa.