Genomic and virulence analysis of in vitro cultured Cryptosporidium parvum.

Recent advances in the in vitro cultivation of Cryptosporidium parvum using hollow fiber bioreactor technology (HFB) have permitted continuous growth of parasites that complete all life cycle stages. The method provides access to all stages of the parasite and provides a method for non-animal production of oocysts for use in clinical trials. Here we examined the effect of long-term (>20 months) in vitro culture on virulence-factors, genome conservation, and in vivo pathogenicity of the host by in vitro cultured parasites. We find low-level sequence variation that is consistent with that observed in calf-passaged parasites. Further using a calf model infection, oocysts obtained from the HFB caused diarrhea of the same volume, duration and oocyst shedding intensity as in vivo passaged parasites.

Glucocorticoid response to naturalistic interactions between children and dogs.

Although research has shown that pets appear to provide certain types of social support to children, little is known about the physiological bases of these effects, especially in naturalistic contexts. In this study, we investigated the effect of free-form interactions between children (ages 8-10 years) and dogs on salivary cortisol concentrations in both species. We further investigated the role of the child-dog relationship by comparing interactions with the child's pet dog to interactions with an unfamiliar dog or a nonsocial control condition, and modeled associations between survey measures of the human-animal bond and children's physiological responses. In both children and dogs, salivary cortisol decreased from pre- to post-interaction; the effect was strongest for children interacting with an unfamiliar dog (compared to their pet dog) and for the pet dogs (compared to the unfamiliar dog). We found minimal evidence for associations between cortisol output and behaviors coded from video, but children scoring higher on survey measures of the human-animal bond exhibited the greatest reductions in cortisol when interacting with dogs. Self-reported loneliness was not related to cortisol or the human-animal bond, but measures of both loneliness and the human-animal bond were higher among children who participated after the onset of the COVID-19 pandemic, relative to those who participated before the pandemic. This study builds on previous work that investigated potential stress-buffering effects of human-animal interaction during explicit stressors and demonstrates important physiological correlates of naturalistic interactions between children and dogs, similar to those that occur in daily life.

Effects of human-animal interaction on salivary and urinary oxytocin in children and dogs.

Oxytocin pathways are hypothesized to play important roles in human-animal interactions and may contribute to some benefits of these interspecific social relationships. We explored the effects of naturalistic interactions between children and dogs on oxytocin release in both species, as well as associations between methylation of the oxytocin receptor gene (OXTRm), social behavior, and oxytocin response in this context. Children (N = 55) participated in a within-subjects design involving a) interaction with their pet dog, b) interaction with an unfamiliar dog, and c) a nonsocial control condition (solitary play). We used immunoassays to measure salivary and urinary oxytocin in both the children and dogs, behavioral coding to characterize dog-child interactions, and bisulfite sequencing to quantify methylation of the oxytocin receptor gene (N = 32 children). Child salivary oxytocin decreased moderately across time in all conditions, but the extent of this effect varied between conditions, with greater oxytocin output during interactions with dogs than the control condition. In the pet dog condition, children's salivary oxytocin response was positively associated with the duration of visual co-orientation between the child and dog. Child urinary oxytocin did not deviate substantially from baseline in any condition. Children with higher levels of OXTRm had greater oxytocin output during interactions with their pet dogs, but lower oxytocin output in the control condition, and engaged in lower levels of affectionate interaction with dogs across conditions. Children's pet dogs exhibited increases in salivary oxytocin, but we observed the opposite pattern in the unfamiliar dog, who exhibited decreases in both urinary and salivary oxytocin on average. Collectively, our results support the hypothesis that oxytocin pathways may shape and respond to social interactions between children and dogs, highlighting an important role for companion animals in child development.

Neurophysin I is an analytically robust surrogate biomarker for oxytocin.

Oxytocin is a pleiotropic neuropeptide that plays roles in biological processes ranging from birth, lactation, and social bonding to immune function, cardiovascular repair, and regulation of appetite. Although measurements of endogenous oxytocin concentrations have been performed for more than 50 years, the ability to measure oxytocin accurately poses notable challenges. One potential solution for overcoming these challenges involves measurement of oxytocin's carrier molecule - neurophysin I (NP-1) - as a surrogate biomarker. NP-1 is secreted in equimolar concentrations with oxytocin but has a longer half-life, circulates in higher concentrations, and can be measured using a sandwich immunoassay. We report experiments that 1) analytically validate a commercially available NP-1 sandwich immunoassay for use with human plasma and urine samples, 2) confirm the specificity of this assay, based on detection of NP-1 in plasma from wild-type but not oxytocin knockout mice, 3) demonstrate that NP-1 concentrations are markedly elevated in late pregnancy, consistent with studies showing substantial increases in plasma oxytocin throughout gestation, and 4) establish strong correlation between NP-1 and plasma oxytocin concentrations when oxytocin is measured in extracted (but not non-extracted) plasma. The NP-1 assay used in this study has strong analytical properties, does not require time-intensive extraction protocols, and the assay itself can be completed in < 2 h (compared to 16-24 h for a competitive oxytocin immunoassay). Our findings suggest that much like copeptin has become a useful surrogate biomarker in studies of vasopressin, measurements of NP-1 have similar potential to advance oxytocin research.

Plasma cholinesterase levels and health symptoms in peruvian farm workers exposed to organophosphate pesticides.

The purpose of this study was to examine plasma cholinesterase (PChE) changes and the adverse health effects associated with chronic low-dose exposure to organophosphates (OPs) in a Peruvian agricultural population. A cross-sectional study with a clinical interview and blood tests was performed among 213 farm workers from two subtropical valleys in Peru. The control group consisted of 78 nonexposed workers from the same areas. PChE levels from the two exposed subgroups (pesticide applicators and other agricultural jobs) were significantly lower than those of controls (1554 +/- 315 U/l, 1532 +/- 340 U/l, and 1787 +/- 275 U/l, respectively). Fifteen percent of the exposed population reported a past poisoning by pesticides, all of them needing medical evaluation and treatment. They had significantly lower PChE levels as compared to those without this antecedent. Approximately 61% of the exposed workers reported pesticide-related symptoms, but no significant difference was found in their PChE as compared to workers without symptoms. On the other hand, the use of personal protective equipment (PPE) was significantly associated with higher PChE levels and with a lower risk of reporting pesticide-related symptoms, which supports the benefit from using appropriate protective measures. In conclusion, data indicate that farm workers exposed to OPs in developing countries need to be monitored by means of PChE and an examination of their clinical status, which would allow identification of farm workers most at risk from pesticide toxicity. The use of correct PPE is highly recommended.

Distribution of paraoxonase-1 gene polymorphisms and enzyme activity in a Peruvian population.

Paraoxonase-1 (PON1) is a serum esterase associated with high density lipoproteins and capable of detoxifying toxic metabolites of organophosphorus (OP) compounds. Two major polymorphisms have been described in the coding region of the PON1 gene at positions 192 and 55 and at least five in the 5'-regulatory region, the most important at position -108. Depending on the substrate, PON1 192 Q/R polymorphism can affect PON1 enzymatic activity. In the present study, we have determined the distribution of the PON1 192 Q/R and -108 C/T polymorphisms in a Peruvian population and compared the distribution of these polymorphisms with those of other world populations. PON1 phenotype and enzyme activity also were measured as they can influence the population resistance to the toxicity of OP compounds. The genotype distribution at position 192 was: QQ = 0.236, QR = 0.607, and RR = 0.157; and distribution at position -108 was: CC = 0.315, CT = 0.596, and TT = 0.089. The frequencies of the high activity R and C alleles were 0.461 and 0.613, respectively. The frequency of the PON1 192 Q allele was significantly lower than that of American, Caucasian-American, European-Brazilian, and Costa Rican samples. Outside the American continent, the frequency of this allele was lower than for all European countries, Thais, and Indians, but higher than for Chinese or Japanese. Regarding the toxicological importance of these polymorphisms, it was inferred that PON1 phenotyping (assessment of the R alloform) and genotyping (determination of the PON1 -108TT genotype) could be helpful as individual markers of susceptibility. PON1 phenotyping may be useful in further epidemiological studies involving agriculture workers occupationally exposed to OP compounds in developing countries.