Quantifying replication slippage error in Cryptosporidium metabarcoding studies.

Genetic variation in Cryptosporidium, a common protozoan gut parasite in humans, is often based on marker genes containing trinucleotide repeats, which differentiate subtypes and track outbreaks. However, repeat regions have high replication slippage rates, making it difficult to discern biological diversity from error. Here, we synthesised Cryptosporidium DNA in clonal plasmid vectors, amplified them in different mock community ratios and sequenced them using next generation sequencing to determine the rate of replication slippage with dada2. Our results indicate that slippage rates increase with the length of the repeat region and can contribute to error rates of up to 20%.

Absence of Cryptosporidium hominis and dominance of zoonotic Cryptosporidium species in patients after Covid-19 restrictions in Auckland, New Zealand.

Coronavirus disease-2019 (Covid-19) nonpharmaceutical interventions have proven effective control measures for a range of respiratory illnesses throughout the world. These measures, which include isolation, stringent border controls, physical distancing and improved hygiene also have effects on other human pathogens, including parasitic enteric diseases such as cryptosporidiosis. Cryptosporidium infections in humans are almost entirely caused by two species: C. hominis, which is primarily transmitted from human to human, and Cryptosporidium parvum, which is mainly zoonotic. By monitoring Cryptosporidium species and subtype families in human cases of cryptosporidiosis before and after the introduction of Covid-19 control measures in New Zealand, we found C. hominis was completely absent after the first months of 2020 and has remained so until the beginning of 2021. Nevertheless, C. parvum has followed its typical transmission pattern and continues to be widely reported. We conclude that ~7 weeks of isolation during level 3 and 4 lockdown period interrupted the human to human transmission of C. hominis leaving only the primarily zoonotic transmission pathway used by C. parvum. Secondary anthroponotic transmission of C. parvum remains possible among close contacts of zoonotic cases. Ongoing 14-day quarantine measures for new arrivals to New Zealand have likely suppressed new incursions of C. hominis from overseas. Our findings suggest that C. hominis may be controlled or even eradicated through nonpharmaceutical interventions.

Draft Genome Assemblies of Two Cryptosporidium hominis Isolates from New Zealand.

Cryptosporidium hominis is a protozoan parasite that causes gastrointestinal disease in humans worldwide. Here, we report on draft whole-genome sequences of two clinical isolates of C. hominis that were purified from patients with cryptosporidiosis in New Zealand.

Development of sibling inbred sea urchins: normal embryogenesis, but frequent postembryonic malformation, arrest and lethality.

Inbred lines of Strongylocentrotus purpuratus descended from a single pair of wild animals were constructed by sibling mating. We describe results from a systematic series of crosses in which eggs from F2 and from F3 females were fertilized respectively with sperm from their sibling males. Observations were also made on self-fertilized cultures derived from several naturally occurring hermaphrodites. Morphological development, survival efficiency, and expression of three territorial embryonic markers were assayed in the embryos developing from these crosses. Unexpectedly, out of > 90 controlled crosses, we observed no developmental failures whatsoever, up to the end of embryogenesis (i.e., onset of feeding) that could be attributed to homozygous, zygotically acting recessive genes. However, during postembryonic larval development, lethality, morphological malformation, and arrest are observed in inbred cultures at a high frequency. The incidence of these zygotic developmental failures is such that it appears that there is at least one recessive genetic defect affecting larval development per haploid parental genome. The relative imperviousness of the basic embryonic process to defects arising from homozygosity is consistent with other evidence implying that territorial specification in sea urchin embryogenesis is controlled by maternally rather than zygotically expressed gene products.

Load-insensitive assessment of myocardial performance after tumor necrosis factor-alpha in dogs.

Tumor necrosis factor-alpha (TNF alpha) has been implicated as an endogenous mediator of the cardiovascular manifestations of sepsis and septic shock. We studied the acute effects of a single dose (50 or 200 micrograms/kg) of intravenous recombinant human TNF alpha (rhTNF alpha) on myocardial function in halothane-anesthetized dogs. Regional cardiac dimensions were measured by using sonomicrometry. Intracavitary left ventricular, ascending aortic, and pulmonary artery pressures were measured by use of micromanometers. Cardiac index was determined by means of thermodilution. Myocardial performance was analyzed by assessing changes in the slope of the left ventricular end-diastolic length-stroke work relationship obtained by performing transient vena caval occlusions. Animals were resuscitated by means of normal saline solutions to maintain baseline regional end-diastolic length. Over a 3-hour period of observation, rhTNF alpha decreased systemic vascular resistance index, but the cytokine did not compromise intrinsic myocardial performance. The circulatory response to rhTNF alpha was a hyperdynamic state characterized by tachycardia, augmented cardiac index, and increased intrinsic myocardial contractility (leftward shift of the left ventricular end-diastolic length-stroke work relationship). In addition, rhTNF alpha caused systemic acidosis and increased plasma levels of prostacyclin metabolite (6-keto-prostaglandin F1 alpha). After the dose of rhTNF alpha large volumes of fluid were required to maintain baseline end-diastolic length. We conclude that in the acute setting, rhTNF alpha elicits abnormalities in peripheral vascular tone that are not accompanied by depression of myocardial function.

The effectiveness of preterm-birth prevention educational programs for high-risk women: a meta-analysis.

OBJECTIVE: To evaluate whether preterm-birth prevention educational programs are effective at reducing neonatal mortality, low birth weight (LBW), and preterm delivery. DATA SOURCES: A MEDLINE literature search of English-language studies was performed, supplemented by a bibliography search of original research and review articles to locate studies assessing preterm-birth prevention programs. METHOD OF STUDY SELECTION: We identified 31 studies that reported results from trials evaluating preterm-birth prevention programs. From this group, only the six randomized controlled trials evaluating preterm-birth prevention education programs satisfied criteria of homogeneity to be included in a meta-analysis. One of these six studies was a subset of another study and was excluded except when reporting outcomes that were not included in the larger report. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers assessed study methodology and identified the following outcomes: LBW frequency, preterm birth frequency, neonatal survival, birth weight, gestational age at delivery, and preterm labor diagnosis rates. When data were combined using meta-analytic techniques, no significant benefits were found for preterm-birth education programs in preventing neonatal death (cumulative relative risk [RR] 1.00, 95% confidence interval [CI] 0.99-1.01), LBW rates (RR 0.99, 95% CI 0.88-1.11), or preterm delivery rates (RR 1.08, 95% CI 0.92-1.27). The only statistically significant effect of preterm birth education programs appears to be an increase in the frequency at which preterm labor is diagnosed (RR 1.71, 95% CI 1.41-2.08). CONCLUSION: Preterm-birth prevention educational programs appear to have little benefit in reducing preterm birth and may result in an increased rate of diagnosis of preterm labor.

Sodium bicarbonate versus Carbicarb in canine myocardial hypercarbic acidosis.

The objective of this study was to compare the in vivo effects of sodium bicarbonate (NaHCO3) and Carbicarb infusion on regional contractile performance and acid-base status in the setting of hypercarbic acidosis. Animals (N = 9) were anesthetized and paralyzed using sodium pentothal, halothane, and pancuronium bromide, and mechanically ventilated with an air-O2 mixture so that arterial PO2 was > or = 300 mm Hg. Following beta-adrenergic blockade, alveolar ventilation was gradually reduced over a 50-minute period to increase arterial PCO2 to 60 to 80 mm Hg. Each of the following solutions was then infused in consecutive order directly into the left anterior descending artery coronary artery for 15 minutes: (1) 8.4% NaHCO3 at 2 mL/min; (2) 5% sodium chloride at 2 mL/min, equivalent to NaHCO3 in osmolality; (3) 6.3% Carbicarb at 0.5 mL/min, equivalent to NaHCO3 in buffer capacity; and (4) 6.3% Carbicarb at 2 mL/min, equivalent to NaHCO3 in volume. Regional stroke work analog (ultrasonic dimension transducers), interstitial myocardial pH (Khuri electrode), coronary blood flow (doppler flow probe), and hemodynamic/metabolic variables (heart rate, blood pressure, arterial and coronary venous blood gases) were measured at 1, 5, 10, and 15 minutes during each infusion and 10 minutes after the infusion was discontinued, ie, at 25 minutes. Animals were allowed to recover for 45 minutes between interventions. Values at each time point were compared with baseline for statistical significance. Small reductions in interstitial myocardial pH (P < .05) and stroke work (P > .05) were observed within 1 minute of NaHCO3 administration. Both parameters increased significantly from baseline levels thereafter, ie, interstitial myocardial pH at 5 minutes and stroke work at 15 minutes. Infusion of Carbicarb invariably was associated with an increase (P < .05) in interstitial myocardial pH. Stroke work increased (P < .05) during low-dose Carbicarb administration, but infusion of the higher dose was accompanied by a biphasic response, ie, an increase (P < .05) from 0 to 5 minutes, followed by a gradual decrease that achieved statistical significance 10 minutes after termination of the infusion. End-diastolic length was inversely proportional to changes in stroke work, and coronary blood flow varied directly with changes in coronary venous Pco2. Myocardial O2 consumption decreased (P < .05) during Carbicarb infusion, but changes during NaHCO3 did not reach statistical significance. Our findings lend support to the hypothesis that intramyocardial pH determines myocardial function independent of CO2 production by buffer therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

The induction of myocardial damage by open-chest low-energy countershock.

Anesthetized rabbits were used to study the effects of internal electrical defibrillation on the heart. Single electrical shocks of 0.5, 1.0, and 3.0 Wsec/kg or five consecutive shocks of 0.5 Wsec/kg spaced at either 1 shock per min, per 2 min, or per 3 min, were used. Half of the rabbits given a single shock of 1 Wsec/kg or multiple shocks at a spacing of 1 shock per min were given intravenous injection of dexamethasone sodium phosphate (6 mg/kg) 5 min before receiving the defibrillatory shocks. Damage to the hearts was assessed by electrocardiography and histopathology. Myocardial damage was evident at the lowest energy levels used. All indices showed that the degree of damage was increased by increasing the energy level of single shocks or by decreasing the time interval between multiple shocks. The steroid pretreatment did not appear to protect the hearts from damage caused by the shocks.