Doctor of Philosophy

dissertationCone snails are predatory marine gastropods that use venom to capture prey. Components of the cone snail venom are small peptidic compounds called conotoxins which target ion channels, receptors, and transporters in the prey’s nervous system. Conotoxins are highly potent and specific towards their molecular target, thus, they are used as tools for the understanding of how the nervous system works. Moreover, conotoxins are also powerful leads for developing new drugs. A conotoxin, omega-MVIIA is now sold as the drug Prialt for the treatment of pain. Given the tremendous research and pharmacological applications of these compounds, it is thus important to pursue further research aimed at discovering novel conotoxins. For this research I aimed to discover novel conotoxins using two biological assays that were not previously used in conotoxin discovery. One assay measured the activity of the norepinephrine transporter (NET) expressed in human embryonic kidney (HEK) cells to reuptake radiolabeled norepinephrine and another assay used calcium imaging of dissociated mouse dorsal root ganglion (DRG) neurons. Further, I focused my research on cone snail clades with limited toxinological information. Chapter 2 describes two conotoxins whose activities were identified using the NET assay. These conotoxins chi-AuID and chi-AoIC were isolated from the venom of mollusk-hunters Conus aulicus and Conus araneosus, respectively. The conotoxin fv1a from Conus furvus another mollusk-hunting cone snail is also reported. The conotoxin fv1a does not inhibit NET, however, this conotoxin shows activity in vivo in mice and in calcium imaging of DRG neurons. The three conotoxins presented in Chapter 2 are homologous, however, they do not have the same pharmacological property. Thus, a comparison of the sequences of chi-AuID, chi-AoIC, and fv1a allowed for the identification of amino acids important for NET inhibition. Chapter 3 describes glycine-rich conotoxins identified from the venom of worm-hunting snails in the Virgiconus clade. vi6a, the first conotoxin identified in this group, was purified from the venom of Conus virgo using calcium imaging. This conotoxin elicited an excitatory behavior in mice when injected intracranially (IC) and intraperitoneally (IP). Conotoxins homologous to vi6a were further identified from Conus terebra and Conus kintoki using molecular biology techniques. Interestingly, C. virgo expresses two additional conotoxins homologous to vi6a. Chapter 4 describes the characterization of pruriceptors in the mouse DRG that are responsive to histamine and chloroquine. Three major populations of neurons were identified and these populations were further characterized using various pharmacological agents to identify the constellation of ion channels and receptors expressed in the membrane of these neurons. Using the conotoxin mu-PIIIA, the expression of Nav1.7 and Nav1.8 in these pruriceptor populations were identified

Determinación del Potencial de Membrana Mitocondrial mediante citometría de flujo durante el proceso de criopreservación de espermatozoides epididimarios de alpacas

El potencial de membrana mitocondrial (PMM) es uno de los parámetros espermáticos más importantes debido a que las mitocondrias son la principal fuente de ATP necesaria para la movilidad espermática en el tracto reproductivo de la hembra para lograr la fecundación. La criopreservación de espermatozoides es una técnica que permite y facilita el uso de material genético de alto valor. El objetivo es demostrar mediante la citometría de flujo que el porcentaje de espermatozoides de alpaca con alto PMM se reduce significativamente luego del proceso de criopreservación. Se trabajaron con 41 testículos de alpaca obtenidos del Camal Municipal de Ninacaca. Provincia de Pasco. Se recuperaron los espermatozoides de la cola del epidídimo con 1 mL de dilutor en base a leche descremada y se congelaron. Sólo fueron congeladas las muestras con mínimo 30% de motilidad y concentración de 50x106 espermatozoides/mL. La evaluación de PMM se realizó antes y después del proceso de criopreservación. Cada muestra se incubó durante 10 minutos a 38 °C con MitoTracker Deep Red (100 nM) para determinar el porcentaje de alto PMM, mediante citometría de flujo con imágenes. El efecto de la criopreservación en el porcentaje de espermatozoides con alto PMM fue evaluado mediante la prueba de T-student pareada. Asimismo, se correlacionaron los porcentajes de motilidad y espermatozoides con alto PMM. Se obtuvo un 49.82 ± 12.41% de alto PMM en muestras antes del proceso de criopreservación, el cual fue significativamente (p<0.05) mayor al porcentaje de alto PMM de las muestras descongeladas (34.97 ± 9.96%). También se encontró una correlación positiva (r: 0.62; p<0.0001) entre motilidad y PMM. Se concluye que el PMM se reduce significativamente luego del proceso de criopreservación, parámetro relacionado a la motilidad espermática.Tesi

Effect of supplementation during pregnancy with L-arginine and antioxidant vitamins in medicalfood on pre-eclampsia in high risk population: Randomised controlled trial

Objective To test the hypothesis that a relative deficiency in L-arginine, the substrate for synthesis of the vasodilatory gas nitric oxide, may be associated with the development of pre-eclampsia in a population at high risk. Design Randomised, blinded, placebo controlled clinical trial. Setting Tertiary public hospital in Mexico City. Participants Pregnant women with a history of a previous pregnancy complicated by pre-eclampsia, or pre-eclampsia in a first degree relative, and deemed to be at increased risk of recurrence of the disease were studied from week 14-32 of gestation and followed until delivery. Interventions Supplementation with a medical food—bars containing L-arginine plus antioxidant vitamins, antioxidant vitamins alone, or placebo—during pregnancy. Main outcome measure Development of pre-eclampsia/eclampsia. Results 222 women were allocated to the placebo group, 228 received L-arginine plus antioxidant vitamins, and 222 received antioxidant vitamins alone. Women had 4-8 prenatal visits while receiving the bars. The incidence of pre-eclampsia was reduced significantly (χ(2)=19.41; P<0.001) in women randomised to L-arginine plus antioxidant vitamins compared with placebo (absolute risk reduction 0.17 (95% confidence interval 0.12 to 0.21). Antioxidant vitamins alone showed an observed benefit, but this effect was not statistically significant compared with placebo (χ(2)=3.76; P=0.052; absolute risk reduction 0.07, 0.005 to 0.15). L-arginine plus antioxidant vitamins compared with antioxidant vitamins alone resulted in a significant effect (P=0.004; absolute risk reduction 0.09, 0.05 to 0.14). Conclusions Supplementation during pregnancy with a medical food containing L-arginine and antioxidant vitamins reduced the incidence of pre-eclampsia in a population at high risk of the condition. Antioxidant vitamins alone did not have a protective effect for prevention of pre-eclampsia. Supplementation with L-arginine plus antioxidant vitamins needs to be evaluated in a low risk population to determine the generalisability of the protective effect, and the relative contributions of L-arginine and antioxidant vitamins to the observed effects of the combined treatment need to be determined. Trial registration Clinical trials NCT00469846

Hyperspectral imaging benchmark based on machine learning for intraoperative brain tumour detection

publishedVersio

PARÁMETROS BIOLÓGICOS DE APANTELES NR. ARISTOTELIAE (VIERECK) (HYMENOPTERA: BRACONIDAE), PARASITOIDE DEL ENROLLADOR DE LAS HOJAS, AMORBIA SP. (LEPIDOPTERA: TORTRICIDAE)

Apanteles nr. Aristoteliae (Viereck) (Hymenoptera: Braconidae) is an endoparasitoid of the leafroller Amorbia sp. (Lepdidoptera: Tortricidae) larvae. In this study, the life cycle, parasitism, sex ratio, and longevity of adults of this parasitoid were determined under laboratory conditions (22 ± 2 ºC, 60 ± 5% relative humidity, and a photoperiod of 16:8h [light:dark]). The life cycle of this parasitoid was 42.45 ± 0.76 days. The duration of development stages of egg-larva, pupa and adult was 14.04 ± 0.05, 9.22 ± 0.07, and 19.36 ± 0.74 days, respectively. Each A. nr. aristoteliae female parasitized 73.33 ± 7.55 Amorbia sp. larvae. The sex ratio of F1 generation was 95.1% males (n = 912). Longevity of adults was significantly different (U = 564, P = 0.01) between mated males (27 ± 2.55 days) and virgins (19.75 ± 0.70 days) but not (U = 182, P = 0.3) between mated females that were exposed to parasitization during all its life (26.4 ± 2.88 days), and virgins (23.13 ± 1.4 days). In order to obtain a better understanding about life parameters of A. nr. aristoteliae, future studies that include different rearing conditions (e.g., temperature and space) are needed.Apanteles nr. aristoteliae (Viereck) (Hymenoptera: Braconidae) es un endoparasitoide de larvas del enrollador de las hojas Amorbia sp. (Lepidoptera: Tortricidae). En este estudio se determinó, bajo condiciones de laboratorio (22 ± 2 ºC, 60 ± 5% de humedad relativa y un fotoperiodo de 16:8 h [luz: oscuridad]) el ciclo de vida, parasitismo, proporción sexual y longevidad de adultos de este parasitoide. La duración del ciclo de vida fue de 42.45 ± 0.76 días. El tiempo de desarrollo de los estados de huevolarva, pupa y adulto fue de 14.04 ± 0.05, 9.22 ± 0.07 y 19.36 ± 0.74 días, respectivamente. A lo largo de toda su vida, cada hembra de A. nr. aristoteliae parasitó 73.33 ± 7.55 larvas del enrollador de las hojas Amorbia sp. La proporción sexual de la generación F1 fue de 95.1% machos (n = 912). La longevidad de los adultos fue significativamente distinta (U = 564, P = 0.01) entre los machos apareados (27 ± 2.55 días) y vírgenes (19.75 ± 0.70 días), pero no (U = 182, P = 0.3) entre las hembras apareadas y que fueron sometidas a parasitación durante toda su vida (26.4 ± 2.88 días) y vírgenes (23.13 ± 1.4 días). Con el fin de obtener un mejor conocimiento de los parámetros de vida del parasitoide A. nr. aristoteliae, es necesario realizar futuros estudios que incluyan diferentes condiciones de cría (ej., temperatura y espacio)

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity &gt; 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Fisicoquímica del agua y cosecha de fitoplancton en una laguna costera tropical

Se analizaron los nutrientes y el fitoplancton de la laguna costero de Mecoacán, al sur del golfo de México. La hidroquímica estuarina y su condición dinámica son indicadores de la composición del fitoplancton. Los resultados obtenidos muestran el predominio de la diatomea Skeletonema costalum, con una afinidad estuarina, además de un alta contenido de amonio