Post-operative dysnatremia is associated with adverse early outcomes after surgery for congenital heart disease.

BACKGROUND: Dysnatremia is a common disorder in critically ill surgical children. The study's aim is to determine the prevalence of dysnatremia and its association with outcomes after surgery for congenital heart disease (CHD). METHODS: This is a single-center retrospective cohort study of children <18 years of age undergoing surgery for CHD between January 2012 and December 2014. Multivariable logistic regression analysis was used to evaluate the relationship between dysnatremia and outcomes during the perioperative period. A total of 1345 encounters met the inclusion criteria. RESULTS: The prevalence of pre- and post-operative dysnatremia were 10.2% and 47.1%, respectively. Hyponatremia occurred in 19.1%, hypernatremia in 25.6%. Hypernatremia at 24, 48, and 72 h post-operative was associated with increased hospital mortality (odds ratios (OR) [95% confidence intervals (CI)] 3.08 [1.16-8.17], p = 0.024; 4.35 [1.58-12], p = 0.0045; 4.14 [1.32-12.97], p = 0.0148, respectively. Hypernatremia was associated with adverse neurological events 3.39 [1.12-10.23], p = 0.0302 at 48 h post-operative. Hyponatremia was not associated with any adverse outcome in our secondary analysis. CONCLUSIONS: Post-operative dysnatremia is a common finding in this heterogeneous cohort of pediatric cardiac-surgical patients. Hypernatremia was more prevalent than hyponatremia and was associated with adverse early post-operative outcomes. IMPACT: Our study has shown that dysnatremia was highly prevalent in children after congenital heart surgery with hypernatremia associated with adverse outcomes including mortality. It is important to understand fluid and sodium regulation in the post-operative period in children with congenital heart disease to better address fluid overload and associated electrolyte imbalances and acute kidney injury. While clinicians are generally very aware of the importance of hyponatremia in critically ill children, similar attention should be given to hypernatremia in this population.

The role of CTNNB1 mutations and matrix metalloproteinases (MMPs) in anti-angiogenesis treatment of endometrial carcinoma.

OBJECTIVE: Treatment options and associated biomarkers for advanced and recurrent disease are limited. Endometrial cancers (ECs) with CTNNB1 exon 3 mutations appear to have preferential response to bevacizumab, an anti-angiogenesis treatment, though the mechanism of action is unknown. We aim to identify mediators of bevacizumab-responsive endometrial cancers. METHODS: We analyzed RNA expression from TCGA and protein expression from CPTAC to identify likely targets for ß-catenin overactivity. We then transiently and stably overexpressed ß-catenin in EC cells to confirm the results suggested by our in silico analysis. We performed corroborative experiments by silencing CTNNB1 in mutated cell lines to demonstrate functional specificity. We implanted transduced cells into xenograft models to study microvessel density. RESULTS: CTNNB1-mutated ECs were associated with increased ß-catenin and MMP7 protein abundance (P < 0.001), but not VEGF-A protein abundance. Overexpressing ß-catenin in EC cells did not increase VEGF-A abundance but did increase expression and secretion of MMP7 (P < 0.03). Silencing CTNNB1 in CTNNB1-mutated cells decreased MMP7 gene expression in EC (P < 0.0001). Microvessel density was not increased. CONCLUSIONS: These data provide a mechanistic understanding for bevacizumab-response in CTNNB1-mutated ECs demonstrated in GOG-86P. We hypothesize that overexpressed and secreted MMP7 potentially digests VEGFR-1, releasing VEGF-A, and increasing its availability. These activities may drive the formation of permeable vessels, which contributes to tumor progression, metastasis, and immune suppression. This mechanism is unique to EC and advocates for further clinical trials evaluating this treatment-related biomarker.

Laryngeal Ultrasound Detects Vocal Fold Immobility in Adults: A Systematic Review.

Laryngeal ultrasound (US) is becoming widely accepted for assessing true vocal fold immobility (TVFI), a potential complication of laryngeal and thyroid surgery. The objective of this project is to perform a systematic review and meta-analysis of pooled evidence surrounding laryngeal US as a modality for diagnosing TVFI in adults at risk for the condition in comparison to laryngoscopy as a gold standard. Medical subject heading terms were used to search MEDLINE, Embase, Google Scholar, Web of Science, and the Cochrane Library for relevant citations from January 1, 2000, to June 30, 2020. Studies were included if they involved patients 16 years and older, where laryngeal US was compared to laryngoscopy for TVFI. Studies were excluded if there were insufficient data to compute a sensitivity/specificity table after attempting to contact the authors. Case reports, and case series were also excluded. The initial search returned 1357 citations. Of these, 109 were selected for review utilizing the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Thirty citations describing 6033 patients were included in the final meta-analysis. A bivariate random effects meta-analysis was performed, revealing a pooled sensitivity for laryngeal US of 0.95 (95% confidence interval [CI] 0.88-0.98), a specificity of 0.99 (95% CI 0.97-0.99), and a diagnostic odds ratio of 1328.2 (95% CI 294.0-5996.5). The area under the curve of the hierarchical summary receiver operating characteristic curve was 0.99 (95% CI 0.98-1.00). Laryngeal US demonstrates high sensitivity and specificity for detecting VFI in the hands of clinicians directly providing care to patients.

Assessment of Vocal Cord Motion Using Laryngeal Ultrasound in Children: A Systematic Review and Meta-Analysis.

OBJECTIVES: Laryngeal ultrasound is a nonirradiating, noninvasive method for assessing the upper airway in children. This systematic review and meta-analysis examine available evidence for accuracy of laryngeal ultrasound in diagnosing vocal cord immobility in infants and children after surgery and trauma affecting the vocal cords. DESIGN: Medical subject heading terms were used to search MEDLINE, Embase, Google Scholar, Web of Science, and the Cochrane Library for relevant citations. Publications from January 1, 2000, to June 30, 2020 were included in the search strategy. Study inclusion criteria consisted of randomized control trials and nonrandomized retrospective or prospective observational studies where vocal cord motion was evaluated by laryngeal ultrasound and compared with a reference test. Studies were excluded if there was insufficient data to compute a sensitivity/specificity table. Case reports, case series less than 10, and manuscripts not published in English were also excluded. PATIENTS: Studies which included subjects younger than or equal to 18 years were considered for full article review. SETTINGS: No restrictions on study settings were imposed in this systematic review. MEASUREMENTS AND MAIN RESULTS: The initial search returned 1,357 citations. After de-duplication, abstract, and full review, eight citations were included in the final meta-analysis. A bivariate random-effects meta-analysis was performed, which revealed a pooled sensitivity for laryngeal ultrasound in detecting vocal cord immobility of 91% (95% CI, 83-95%), specificity of 97% (95% CI, 82-100%), diagnostic odds ratio 333.56 (95% CI, 34.00-3,248.71), positive likelihood ratio 31.58 (95% CI, 4.50-222.05), and negative likelihood ratio 0.09 (95% CI, 0.05-0.19). CONCLUSIONS: Laryngeal ultrasound demonstrates high sensitivity and specificity for detecting vocal cord motion in children in a wide range of clinical settings. Laryngeal ultrasound offers a low-risk imaging option for assessing vocal cord function in children compared with the current gold standard of laryngoscopy.

Effects of residential summer camp on body mass index and body composition in type 1 diabetes.

BACKGROUND: Body mass index (BMI) and fat mass may be higher in children with diabetes compared to healthy peers. It is not certain how diabetic children respond to exercise and diet interventions. OBJECTIVE: To investigate the effect of summer camp on BMI and body composition in children with type 1 diabetes. METHODS: Five hundred eighty-six children (5-19 years, 518 with type 1 diabetes, 68 without diabetes) were followed while attending camp. BMI z-scores (BMIz) and body composition (bioelectrical impedance analysis) were measured at the beginning and end of each 19-day session. Diet and activity were directly supervised, blood glucose closely monitored. A nested diabetic/non-diabetic sib pair analysis was also conducted. Changes in BMIz and percent fat mass (%FM) were the primary outcomes. Findings were confirmed by analysis of data from 612 campers (549 with diabetes) the following summer. RESULTS: At entry, campers with diabetes had higher BMIz and %FM. They tended to gain BMIz (0.04 ± 0.01) whereas non-diabetic campers lost (-0.16 ± 0.11, P < .0001). BMIz increases were positively correlated with precamp hemoglobin A1c values. The differences in initial values and changes in BMIz remained when campers with diabetes were compared to their siblings. All experienced a similar reduction in %FM. Similar results were obtained the following summer. CONCLUSIONS: Children with diabetes may, therefore, accrue more lean body tissue with increased exercise and a healthy diet than those without diabetes. This effect is greatest in those with initially poor metabolic control.

Development of a new age-appropriate, chewable tablet of mebendazole 500 mg for preventive chemotherapy of soil-transmitted helminth infections in pre-school and school-age children.

The aim of this study was to develop an age-appropriate tablet of mebendazole 500 mg to be used in large donation programs by the World Health Organization (WHO) for preventive chemotherapy of soil-transmitted helminth (STH) infections in pre-school and school-age children living in tropical and subtropical endemic areas. To that end, a new oral tablet formulation was developed that can be either chewed or given to young (≥1 year old) children by spoon after rapid disintegration to a soft mass with the addition of a small amount of water directly on the spoon. Although the tablet was manufactured using conventional fluid bed granulation, screening, blending, and compression processes, one of the main challenges was to combine properties of a chewable, dispersible, and regular (solid) immediate release tablet to meet the predefined requirements. The tablet disintegration time was below 120 s, allowing for administration by the "spoon method". The tablet hardness was higher (160-220 N) than normally applicable for chewable tablets, permitting shipment along a lengthy supply chain in a primary 200-tablet count bottle packaging. In addition, the resulting tablets are stable for 48 months in all climatic zones (I-IV). In this article, several aspects of the development of this unique tablet are described, including formulation, process development, stability, clinical acceptability testing, and regulatory filing.

MR and CT arthrography of the hip.

CT arthrography (CTa) and MR arthrography (MRa) are useful tools for the investigation of intra-articular hip disease. They are minimally invasive techniques with a very low rate of complications and can be performed safely. CTa or MRa can be performed after an intra-articular injection of diluted contrast, but both techniques can also be performed after a single injection. As radiologists we should be able to address the surgeon's questions and work together to standardize terminology and classifications systems for accurate reporting. This update emphasizes radiological findings with a clinical perspective. CTa and MRa allow the precise diagnosis of labral tears, loose bodies, and intra-articular ligaments (capsular and ligamentum teres). The use of careful technique and a tailored protocol has improved our ability to detect and describe cartilage lesions. This is essential because knowledge of the status of the cartilage may dictate a specific surgical approach, and when cartilage lesions are extensive, they are a negative prognostic indicator for arthroscopic treatment.

Effect of low pH on growth and shell mechanical properties of the Peruvian scallop Argopecten purpuratus (Lamarck, 1819).

Dissolution of anthropogenic CO2 modifies seawater pH, leading to ocean acidification, which might affect calcifying organisms such as bivalve mollusks. Along the Peruvian coast, however, natural conditions of low pH (7.6-8.0) are encountered in the habitat of the Peruvian scallop (Argopecten purpuratus), as a consequence of the nearby coastal upwelling influence. To understand the effects of low pH in a species adapted to these environmental conditions, an experiment was performed to test its consequences on growth, calcification, dissolution, and shell mechanical properties in juvenile Peruvian scallops. During 28 days, scallops (initial mean height = 14 mm) were exposed to two contrasted pH conditions: a control with unmanipulated seawater presenting pH conditions similar to those found in situ (pHT = 7.8) and a treatment, in which CO2 was injected to reduce pH to 7.4. At the end of the experiment, shell height and weight, and growth and calcification rates were reduced about 6%, 20%, 9%, and 10% respectively in the low pH treatment. Mechanical properties, such as microhardness were positively affected in the low pH condition and crushing force did not show differences between pH treatments. Final soft tissue weights were not significantly affected by low pH. This study provides evidence of low pH change shell properties increasing the shell microhardness in Peruvian scallops, which implies protective functions. However, the mechanisms behind this response need to be studied in a global change context.

Thermo-Mechanical and Fungi Treatment as an Alternative Lignin Degradation Method for Bambusa oldhamii and Guadua angustifolia Fibers.

Different strategies have been used to degrade the molecular structure of lignins in natural fibers. Both chemical and biological processes can obtain different types of lignins for industrial use. In this study, a variation of the spectral intensity of the thermo-mechanical and fungi-modified Bambusa oldhamii (giant bamboo) and Guadua angustifolia Kunt fibers were examined via Fouriertransform infrared spectroscopy. The giant bamboo and Guadua angustifolia Kunt specimens were modified using a non-chemical alternative steam pressure method for degrading lignins, followed by mechanical sieving to obtain fibers of different lengths. The obtained fibers were treated with the Fusarium incarnatum-equiseti MF18MH45591 strain in a 21 d degradation process. The samples were subjected to Fouriertransform infrared spectroscopy before and after the strain treatment. The intensity variation was found to be in the spectral range of 1200 cm-1 to 1800 cm-1, in which lignin components are commonly found in most plant species. A multivariate analysis of the principal components of the treated and untreated control samples confirmed the changes in the spectral region of interest, which were associated with the thermo-mechanical and fungal treatment.

Climate vulnerability assessment of key fishery resources in the Northern Humboldt Current System.

The Northern Humboldt Current System sustains one of the most productive fisheries in the world. However, climate change is anticipated to negatively affect fish production in this region over the next few decades, and detailed analyses for many fishery resources are unavailable. We implemented a trait-based Climate Vulnerability Assessment based on expert elicitation to estimate the relative vulnerability of 28 fishery resources (benthic, demersal, and pelagic) to the impacts of climate change by 2055; ten exposure factors (e.g., temperature, salinity, pH, chlorophyll) and 13 sensitivity attributes (biological and population-level traits) were used. Nearly 36% of the species assessed had "high" or "very high" vulnerability. Benthic species were ranked the most vulnerable (gastropod and bivalve species). The pelagic group was the second most vulnerable; the Pacific chub mackerel and the yellowfin tuna were amongst the most vulnerable pelagic species. The demersal group had the relatively lowest vulnerability. This study allowed identification of vulnerable fishery resources, research and monitoring priorities, and identification of the key exposure factors and sensitivity attributes which are driving that vulnerability. Our findings can help fishery managers incorporate climate change into harvest level and allocation decisions, and assist stakeholders plan for and adapt to a changing future.

Vascular calcification and 25-hydroxyvitamin D levels in non-dialysis patients with chronic kidney disease stages 4 and 5.

BACKGROUND: Cardiovascular disease (CVD) is the leading cause of death among chronic kidney disease (CKD) patients. Vascular calcification is highly prevalent in this population and is an independent predictor of cardiovascular mortality. Vascular calcification in uraemic patients is known to be an active and regulated process subject to the action of many promoting and inhibitory factors. The role of vitamin D in this process remains controversial. We evaluated the relationship between serum levels of 25-hydroxyvitamin D (25(OH)D) and vascular calcification evaluated by plain X-ray images, in predialysis patients with CKD stages 4 and 5. METHODS: We performed a cross-sectional study with 210 CKD patients stages 4 and 5 managed at our predialysis unit. Patients were 63.5 ± 13 years of age, 60.5% males, 64.8% diabetics and 47.1% with a history of CVD. Plain X-ray images of pelvis, hands and lateral lumbar spine from all subjects were studied for calculation of semiquantitative vascular calcification scores as described by Adragao and Kauppila. RESULTS: We found a high prevalence of vascular calcification in our population. Adragao scores revealed only 47 patients (22.4%) without vascular calcification and 120 (57.1%) with scores higher than 3. Kauppila scores revealed only 29 patients (13.8%) without aortic calcifications and 114 patients (54.3%) with scores higher than 7. Higher vascular calcification scores were related to older age, diabetes, history of CVD and lower levels of 25(OH)D. Only 18.5% of patients had adequate levels of 25(OH)D (> 30 ng/mL), 53.7% of them had insufficient levels (15-30 ng/mL) and 27.8% had deficient levels (< 15 ng/mL). Multivariate analysis showed that age, diabetes and CVD were directly associated and 25(OH)D levels were inversely associated with vascular calcifications. CONCLUSIONS: Our results show an independent and negative association between serum levels of 25(OH)D and vascular calcification. Further and larger prospective studies are needed to clarify the possible role of vitamin D deficiency in the development of vascular calcification in CKD patients.

Direct MR arthrography of the hip with leg traction: feasibility for assessing articular cartilage.

OBJECTIVE: Hip arthrography is an accurate diagnostic method for evaluation of the peripheral compartment, but its depiction of cartilage lesions is moderate. The purpose of this study was to add leg traction to MR arthrography of the hip to test its effect on visualization of cartilage surfaces. CONCLUSION: Hip MR arthrography with leg traction is a technically feasible and safe procedure that improves visualization of the femoral and acetabular cartilage surfaces.

Amino acid-level signal-to-noise analysis of incidentally identified variants in genes associated with long QT syndrome during pediatric whole exome sequencing reflects background genetic noise.

BACKGROUND: Due to rapid expansion of clinical genetic testing, an increasing number of genetic variants of undetermined significance and unclear diagnostic value are being identified in children. Variants found in genes associated with heritable channelopathies, such as long QT syndrome (LQTS), are particularly difficult to interpret given the risk of sudden cardiac death associated with pathologic mutations. OBJECTIVE: The purpose of this study was to determine whether variants in LQTS-associated genes from whole exome sequencing (WES) represent disease-associated biomarkers or background genetic "noise." METHODS: WES variants from Baylor Genetics Laboratories were obtained for 17 LQTS-associated genes. Rare variants from healthy controls were obtained from the GnomAD database. LQTS case variants were extracted from the literature. Amino acid-level mapping and signal-to-noise calculations were conducted. Clinical history and diagnostic studies were analyzed for WES subjects evaluated at our institution. RESULTS: Variants in LQTS case-associated genes were present in 38.3% of 7244 WES probands. There was a similar frequency of variants in the WES and healthy cohorts for LQTS1-3 (11.2% and 12.9%, respectively) and LQTS4-17 (27.1% and 38.4%, respectively). WES variants preferentially localized to amino acids altered in control individuals compared to cases. Based on amino acid-level analysis, WES-identified variants are indistinguishable from healthy background variation, whereas LQTS1 and 2 case-identified variants localized to clear pathologic "hotspots." No individuals who underwent clinical evaluation had clinical suspicion for LQTS. CONCLUSION: The prevalence of incidentally identified LQTS-associated variants is ∼38% among WES tests. These variants most likely represent benign healthy background genetic variation rather than disease-associated mutations.

Focal segmental glomerulosclerosis due to a relapsing non-Hodgkin's lymphoma diagnosed by positron emission tomography.

Glomerulonephritis rarely appears associated with Hodgkin's disease or non-Hodgkin's lymphoma (NHL). We present a patient with a relapse of a non-Hodgkin's lymphoma which first presented as nephrotic syndrome due to focal segmental glomerulosclerosis (FSGS). This case report discusses the unusual association of non-Hodgkin's lymphoma and focal segmental glomerulosclerosis, as well as the crucial role of positron emission tomography in detecting the relapsing lymphoma.

Cystatin C as marker of residual renal function in patients on peritoneal dialysis: relation with parameters of peritoneal function.

INTRODUCTION: Cystatin C (CysC) is a nonglycosylated protein of low molecular weight not influenced by age, sex or inflammation. The aim of this paper is to ascertain the usefulness of serum CysC level determination in peritoneal dialysis (PD) patients. MATERIAL AND METHODS: CysC serum levels were determined in 80 PD patients. The mean age of patients was 53.7 +/- 15 years, with 15.3 +/- 25.8 months on PD. Thirty-three percent were on continuous ambulatory peritoneal dialysis (CAPD) and 66.3% on automated peritoneal dialysis (APD). Fourteen patients (17%) had no residual renal function (RRF). RESULTS: Mean CysC levels were 5.8 +/- 1.4 mg/L, without differences between men (5.5 +/- 1.4 mg/L) and women (5.6 +/- 1.5 mg/L, NS). There was no correlation between CysC levels and age, weight, height or time on PD. Anuric patients had CysC levels significantly higher than non-anuric (6.7 +/- 1.4 vs. 5.3 +/- 1.3 mg/L, p<0.001). CysC levels showed an inverse correlation with RRF (r=-0.60, p<0.001) and residual urine volume (r=-0.58, p<0.001). CONCLUSIONS: In conclusion, serum CysC levels had the same statistical significance as plasma creatinine levels, and they are not influenced by peritoneal transport in PD patients. Consequently, both parameters are valid RRF markers.

Peritoneal transport in peritoneal dialysis patients is not affected by transitorily successful renal transplantation.

Patients returning to peritoneal dialysis (PD) from failed renal transplantation are recognized to be inflamed, and this situation might produce a high peritoneal solute transport status. We wanted to determine if a period of time with a kidney allograft induces a change in peritoneal function. We studied 19 PD patients who had been living with a graft for a mean of 47 +/- 39 months. We studied their peritoneal function upon starting PD (baseline), immediately before transplantation (pre-Tx), and after returning to PD when the graft failed (post-Tx). We analyzed the peritoneal mass transfer coefficients for urea (U-MTAC) and creatinine (Cr-MTAC), the dialysate-to-plasma ratio of creatinine (D/P-Cr), and net ultrafiltration (UF). We observed no significant differences in the various variables pre-Tx and post-Tx. The U-MTAC post-Tx was significantly lower than at PD baseline (25.9 +/- 8 mL/min vs. 20.2 +/- 5 mL/min, p = 0.03). The U-MTAC and Cr-MTAC post-Tx were not correlated with months on a graft or with MTAC values at baseline. In inherent high transporters (Cr-MTAC > or = 11.5 mL/min at baseline, n = 8), we observed a significant reduction in Cr-MTAC post-Tx (15.2 +/- 2 mL/min vs. 10.2 +/- 4 mL/min, p = 0.03). Three of these patients remained high transporters post-Tx. We conclude that peritoneal function upon reinitiating PD after transplantation is similar to function in the pre-transplantation phase; and that a high peritoneal transport status is more prevalent at first initiation onto PD than at return after transplantation, suggesting that inherently high transport is almost exclusively a feature of an intact, predialysis peritoneum.

Introducción de vídeojuegos en el tratamiento convencional de la ambliopía funcional / Incorporation of videogames into the conventional treatment for functional amblyopia

RESUMEN Objetivo: Valorar la efectividad del vídeojuego en educandos que padecen ambliopía funcional. Métodos: Se confeccionó la historia clínica de cada paciente, la cual incluyó la revisión oftalmológica completa, la evaluación de la agudeza visual con la prueba adecuada a cada edad, y se evaluó la presencia de supresión mediante la prueba de filtro rojo y las luces de Worth. Cada prueba se realizó de forma individual según el tipo y la severidad de la ambliopía, y se le indicó la refracción correspondiente. Los pacientes se dividieron en dos grupos: al grupo A se le aplicó la terapia tradicional de la ambliopía, y al grupo B se le siguió la misma pauta que un tratamiento tradicional de ambliopía, pero con la introducción de vídeojuegos. Resultados: Se observó en el grupo A un predominio de los pacientes con agudeza visual inicial entre 0,2 - 0,4 (50 %), la cual se incrementó en dos líneas o más en el (55 %); sin embargo, en el grupo B la agudeza inicial entre 0,2 - 0,4 fue de 56,5 %. Los resultados sensoriales seis meses posteriores al tratamiento, según cada grupo de estudio, mostraron en el grupo B una reducción de la supresión en el 91,3 %, y en el grupo A de un 75 %. Conclusión: La terapia visual combinada con vídeojuego es efectiva; mejora la agudeza visual; elimina y reduce la supresión, por lo que constituye una herramienta que complementa la terapia visual tradicional de la ambliopía.

ABSTRACT Objective: Assess the effectiveness of videogames for students suffering from functional amblyopia. Methods: A clinical record was developed for each patient, which included complete ophthalmological examination, visual acuity evaluation with the suitable test for each age, and determination of the presence of suppression by the red filter test and the Worth lights test. Each test was conducted individually according to the type and severity of amblyopia, and the corresponding refraction was indicated. The patients were divided into two groups: Group A received traditional amblyopia therapy, whereas Group B underwent traditional amblyopia treatment combined with the incorporation of videogames. Results: Group A showed a predominance of patients with initial visual acuity between 0.2 - 0.4 (50%), which increased two lines or more in 55%. However, in Group B initial visual acuity ranged between 0.2 - 0.4 in 56.5%. Six months after treatment, sensory results were 91.3% suppression reduction in Group B and 75% in Group A. Conclusion: Visual therapy proved effective when combined with videogames: visual acuity improved and suppression was reduced. It is thus a suitable tool to complement the traditional visual therapy for amblyopia.

Spectroscopic and photochemical properties of the lichen compound lobaric acid.

Lichens synthesize and accumulate photoprotective compounds against possible damage induced by UV radiation in the photobiont. A biological model has been recently formulated that allows the use of lichens to evaluate changes at different UV radiation levels. The thermodynamics, photophysical and photochemical properties of lobaric acid were studied in acetonitrile, ethanol and Brij 35(3%) micelles at different pH values. Also the sun protector factor (SPF) was determined by in vitro methods. Lobaric acid was extracted from Stereoculon alpinum Laur. and characterized by means of standard procedures. Solutions were irradiated in oxygen and under nitrogen conditions with a UV medium pressure lamp. Lobaric acid absorbs at 287, 303 nm, and no fluorescence emission was observed. The maximum value of the molar extinction coefficient (5479.6 M(-1) cm(-1)) was obtained in Brij 35 at pH 12. Solubility is pH dependant and is highest in Brij 35 at pH 12 (4.45 x 10(-4) M). Photoconsumption quantum yields ranged between 10(-4) and 10(-5) in aerobic and anaerobic experimental conditions. Lobaric acid SPF was very low (0.5) compared with homosalate (4.0), (reference solar filter). Two pKa values, 5.05 (carboxylic acid group deprotonation) and 9.75 (phenolic OH deprotonation), were determined.

Photostability and photoprotection factor of boldine and glaucine.

Boldine hydrochloride was more photounstable than boldine after irradiation with UVB (lambda = 300 nm). However, photoconsumption quantum yields, for glaucine hydrochloride (6.5 x 10(-2)) and boldine hydrochloride (6.7 x 10(-2)) in air, were quite similar. The photolysis was oxygen dependent in both cases, and the effect over the kinetics after the addition of 2,2,6,6-tetramethyl-1-piperidinyloxy suggested free radicals participation. The fact that the antioxidative capacity of boldine and boldine hydrochloride did not change during the photolysis, suggests that the phenolic structure remains unchanged in the photoproducts, corroborated with the photoproducts analysis. The photoprotection capacity was evaluated before and after irradiation. Results indicate that the values before irradiation are similar for all three compounds, only glaucine increasing its capacity with length of irradiation time.