Differential recovery ability from infections by two blood parasite genera in males of a Mediterranean lacertid lizard after an experimental translocation

Different blood parasites can co-infect natural populations of lizards. However, our knowledge of the host's ability to recover from them (i.e., significantly reduce parasitemia levels) is scarce. This has interest from an ecological immunology perspective. Herein, we investigate the host recovery ability in males of the lizard Psammodromus algirus infected by parasite genera Schellackia and Karyolysus. The role of lizard hosts is dissimilar in the life cycle of these two parasites, and thus different immune control of the infections is expected by the vertebrate host. As Schellackia performs both sexual and asexual reproduction cycles in lizards, we expect a better immune control by its vertebrate hosts. On the contrary, Karyolysus performs sexual reproductive cycles in vectors, hence we expect lower immune control by the lizards. We carried out a reciprocal translocation experiment during the lizards' mating season to evaluate both parasitemia and leukocyte profiles in male lizards, being one of the sampling plots close to a road with moderate traffic. These circumstances provide a combination of extrinsic (environmental stress) and intrinsic factors (reproductive vs. immune trade-offs) that may influence host's recovery ability. We recaptured 33% of the lizards, with a similar proportion in control and translocated groups. Karyolysus infected 92.3% and Schellackia 38.5% of these lizards. Hosts demonstrated ability to significantly reduce parasitemia of Schellackia but not of Karyolysus. This suggests, in line with our predictions, a differential immune relationship of lizards with these parasites, at time that supports that parasites with different phylogenetic origins should be analyzed separately in investigations of their effects on hosts. Furthermore, lizards close to the road underwent a stronger upregulation of lymphocytes and monocytes when translocated far from the road, suggesting a putative greater exposure to pathogens in the latter area.

Advanced Hepatocellular Carcinoma Patients with Poor Access to Systemic Therapy Treated with Definitive Stereotactic Body Radiation Therapy: A Single-Institution Experience in Latin America

PURPOSE/OBJECTIVE(S)

The standard treatment for patients with advanced hepatocellular carcinoma (aHCC) is systemic therapy with or without stereotactic body radiation therapy (SBRT). We present our experience using SBRT as a definitive treatment for aHCC patients with poor access to systemic therapy.

MATERIALS/METHODS

We performed a retrospective review of patients treated with SBRT at the largest institution in Santiago, Chile between June 2016 and September 2022. All patients were deemed unsuitable for another locoregional treatment by the tumor board. We registered demographic, clinical and treatment characteristics. Additionally, treatment response rates using mRECIST criteria, overall survival (OS), local control (LC) and treatment toxicity were reported. We performed a multivariate analysis of variables using Cox proportion hazard ratio for OS and logistic regression for LC.

RESULTS

A total of 59 patients were included (41 males and 18 females; median age: 70 years [range: 38 - 85 years]), with a total of 63 treatment courses. Most common etiologies of chronic liver disease were nonalcoholic fatty liver disease (23%) and chronic alcohol consumption (20%). Most patients were classified as Child-Pugh Class A (80%). Barcelona Clinic Liver Cancer (BCLC) stage was 2%, 11%, 49% and 38% for stages 0, A, B and C, respectively, while macrovascular invasion was present in 10 (18%) of patients. Forty-six patients (73%) had been subjected to prior locoregional therapy and only 5 patients (8,5%) received systemic therapy after SBRT. Median tumor size was 7 cm. (range: 0.95 - 32 cm). Median radiation dose was 40 Gy (range: 26.5 - 50 Gy) in 5 fractions. Evaluation of radiological response was performed in 46 patients (79%), with complete response, partial response, stable disease and progressive disease in 41%, 43%, 7% and 9% of the cohort, respectively. With a median follow-up of 9 months (range: 0 - 58), 34 patients (58%) died with a median OS of 10.8 months (range: 0 - 28 months). At 12 months, OS was 65.2% (95% CI: 50.9 - 76.3) and at 24 months was 40.7% (95% CI: 26.2 - 54.6) In multivariate analysis tumor size (as a continuous variable) was the only significant variable for LC (OR 2.9 [CI 1.1 - 5.3; p 0.03]) and for OS (HR 3.4 [CI 1.3 - 6.7; p< 0.01]). Four patients developed grade 3 toxicity (3 thrombocytopenia and 1 duodenal ulcer) and only two treatments were suspended definitively.

CONCLUSION

Despite systemic therapy is the standard treatment for aHCC, a minor proportion of patients received the standard of care. SBRT is safe, feasible and a well-tolerated treatment option for aHCC with good clinical outcomes. To our knowledge, this is the first cohort reported of patients with aHCC treated with SBRT in Latin America.

Fecal glucocorticoid metabolites and ectoparasites as biomarkers of heat stress close to roads in a Mediterranean lizard

Differences between air and ground temperatures are expected to narrow with the advance of the season in temperate regions (aka seasonal restriction in the availability of thermal microhabitats), which may activate behavioral and physiological responses of ectotherm species adapted to temperate climates. However, according to cost-benefit models of ectotherm thermoregulation, we hypothesize that these responses may also carry some costs. We quantified seasonal shifts in thermoregulatory precision, concentration of fecal glucocorticoid metabolites, and load of ectoparasites in a Mediterranean lizard, Psammodromus algirus. We also tested whether the proximity to a road, a putative source of chronic stress, can facilitate the glucocorticoid-mediated response of lizards to heat stress. As expected, differences between body and environmental temperatures narrowed during the reproductive season and lizards responded by increasing their thermoregulatory precision and the secretion of glucocorticoids, as indicated by metabolites in feces. Interestingly, lizards tended to have higher glucocorticoid concentration when captured far from the road. This might reflect either a putative impairment of the glucocorticoid-mediated response of the lizards to heat stress close to the road or the plastic capability of P. algirus to acclimate to sources of moderate chronic stress. In the latter direction, the increase of both glucocorticoid metabolites and thermoregulatory precision supported that this Mediterranean species responds to environmental thermal restrictions with adaptive behavioral and physiological mechanisms. However, this was also associated with an increase in its susceptibility to ectoparasites, which represents an added cost to the current cost-benefit models of ectotherm thermoregulation.

Kinetics of insulin secretion from MIN6 pseudoislets after encapsulation in a prototype device of a bioartificial pancreas

Xenotransplantation of insulin-secreting cells from nonhuman sources is an alternative therapeutic approach to bypass the shortage of human pancreatic islet tissue for transplantation in order to treat insulin deficiency in type 1 diabetes mellitus. Therefore, we studied the suitability of pseudoislets generated from insulin-secreting MIN6 tissue culture cells to serve as a surrogate for replacement of pancreatic islets after encapsulation in a minicell, representing a prototype of a new bioartificial pancreas device. MIN6 pseudoislets showed an excellent insulin secretory responsiveness with a typical biphasic secretory pattern to glucose stimulation. When encapsulated in the minicell, insulin release from the pseudoislets in response to glucose stimulation was reduced. The initial first phase insulin secretory response was greatly attenuated. In contrast, the first phase insulin secretory response of the encapsulated pseudoislets was restored on stimulation with the sulfonylurea drug tolbutamide. Our results indicate that the reason for the attenuated first phase of release is the restricted permeability of the pores in the separating membrane in the minicell for the hydrophilic glucose molecule rather than a limited permeability for the secretion product insulin. The reduced release of insulin from the encapsulated pseudoislets could be compensated by overexpression of glucokinase in MIN6 cells, which resulted in an increased glucose responsiveness of the pseudoislets for stimulation with glucose. Thus, this minicell is a well-suited miniature test system for the evaluation of the feasibility of encapsulation of insulin-secreting cells and allows the testing of permeability properties of separating membranes in bioartificial pancreas devices.

[Monitoring of sedation]

Once analgesia is assured, sedation has special relevance in the critically ill ventilated patient's global treatment. Sedatives should be adjusted to individual needs, by administering minimal effective doses to achieve the AIM. This aim must be clearly identified, defined at the beginning of the treatment and revised on a regular basis, ideally at least once per shift. Sedation strategies should foresee the different needs throughout the day within dynamic sedation concept framework. Required sedation depth depends on the patient's psychological characteristics, foreseen evolution and patient tolerance to the support techniques used in treatment. Sedation monitoring permits identification and correction of under- or over-sedation, either of which could negatively influence critically ill patient evolution. The over-sedation concept must be applied to all situations where patients receive more sedation than required. This Spanish Society of Critical Care Medicine's Analgesia and Sedation Work Group recommends the Richmond Agitation Sedation Scale, due to its interrelationship with the Confusion Assessment Method Scale (CAM-ICU), for sedation monitoring in patients under light sedation while it recommends bispectral index sedation monitoring in patients under deep sedation. In the latter case, maintaining values under 40 on the bispectral index doesn't produce any benefits except in patients who require a maximum decrease in neuronal metabolism. To avoid recall phenomena, bispectral monitoring is highly advisable in patients treated with neuromuscular blockers.