Species-specific model to predict amphibian metamorphosis.

Exploring the timing of life-history transitions has been a pivotal focus in the field of evolutionary ecology. Studies on amphibian metamorphosis are well suited to investigate this aspect. We propose a species-specific model to predict the optimal metamorphosis point for frog individuals with different larval growth trajectories. Because overall fitness will be determined throughout both aquatic and terrestrial stages, we included growth and survival rates of aquatic and terrestrial stages in the fitness equation. Then we conducted a rearing experiment on a brown frog, Rana ornativentris, as an example to obtain the size at metamorphosis, larval period, and larval growth trajectory. Based on these results, we determined the model's parameters to fit the actual metamorphosis patterns. Because the parameters are supposed to be evolutionarily maintained, our data-driven approach enabled obtaining fundamental ecological information (evolutionally-based life-history parameters) of the target species. Comparing the parameters among species will allow us to understand the mechanisms in determining life-history transition more deeply.

Changes in blood pressure and arterial stiffness monitored using the cardio-ankle vascular index during hemodialysis.

During hemodialysis (HD), blood pressure (BP) changes are frequently observed. However, the mechanism of BP changes during HD has not been fully clarified. The cardio-ankle vascular index (CAVI) reflects the arterial stiffness of the arterial tree from the origin of the aorta to the ankle independent from BP during measurement. Additionally, CAVI reflects functional stiffness in addition to structural stiffness. We aimed to clarify the role of CAVI in regulating the BP system during HD. We included 10 patients undergoing 4-hour HD (total 57 HD sessions). Changes in the CAVI and various hemodynamic parameters were evaluated during each session. During HD, BP decreased and CAVI significantly increased (CAVI, median [interquartile range]; 9.1 [8.4-9.8] [0 min] to 9.6 [9.2-10.2] [240 min], p < 0.05). Changes in CAVI from 0 min to 240 min were significantly correlated with water removal rate (WRR) (r = -0.42, p = 0.002). Changes in CAVI at each measurement point were negatively correlated with ΔBP (Δsystolic BPeach MP, r = -0.23, p < 0.0001; Δdiastolic BPeach MP, r = -0.12, p = 0.029). Whereas one patient exhibited a simultaneous decrease in BP and CAVI during the initial 60 min of HD. Arterial stiffness monitored with CAVI generally increased during HD. CAVI elevation is associated with decreased WWR and BP. An increase in CAVI during HD may reflect the contraction of smooth muscle cells and play an important role in BP maintenance. Hence, measuring CAVI during HD may distinguish the cause of BP changes.

Prognosis of otitis media with effusion in pediatric patients with cleft palate during language-acquisition period treated by simultaneous tympanostomy tube placement with palatoplasty.

OBJECTIVE: Cleft palate (CP) in children is frequently complicated by otitis media with effusion (OME) due to Eustachian tube dysfunction. Although tympanostomy tube (TT) placement can be beneficial in the treatment of OME to prevent short-term hearing loss, there is no consensus regarding the indications for and timing of TT insertion. The present study was performed to define the safety and effectiveness of simultaneous TT placement with palatoplasty during the language-acquisition period. METHODS: We retrospectively reviewed the medical charts of pediatric patients who underwent palatoplasty for CP in a tertiary medical center, Kyoto University Hospital, from June 2010 to October 2018. The TT retention time was estimated using the Kaplan-Meier method. The incidence of OME recurrence was compared among four Veau classification groups based on the patients' sex, type of CP, median TT retention time, and type of fluid. RESULTS: Seventy-six subjects (150 ears) were enrolled in the study. The median follow-up duration was 48.7 months (range, 18.2-108.0 months) after the first TT placement. A first TT retention time of <20.1 months was a significant risk factor for OME recurrence. Subjects with maxillofacial anomaly complex and subjects with cleft lip and palate and an alveolar cleft showed a significantly higher OME recurrence rate than subjects with clefts only in the hard and/or soft palate. There was no significant difference in the occurrence of sequelae between subjects with only a single TT placement and subjects with more than one TT placement. CONCLUSIONS: Based on the findings of the present study, it is reasonable to perform TT insertion at the same time as palatoplasty on patients who meet the indications. This technique may reduce the number of times the patient requires general anesthesia and maintain good middle ear condition during the period of language acquisition between 1 and 3 years of age.

The Role of Cardio-Ankle Vascular Index as a Predictor of Mortality in Patients on Maintenance Hemodialysis.

AIM: Mortality rate of maintenance hemodialysis patients is known to be high. Cardio-ankle vascular index (CAVI) is an index reflecting the proper stiffness of the arterial tree from the origin of the aorta to the ankle. We aimed to clarify the utility of CAVI as a predictor of mortality in hemodialysis patients. The roles of age and nutritional conditions on survival were also examined. METHODS: We followed 242 patients undergoing hemodialysis for 6 consecutive years. Data from 209 patients (mean age was 60 ± 11 years) excluding those with ankle-brachial index <0.90 were then analyzed. CAVI and heart to ankle pulse wave velocity (haPWV) were measured using Vasera 1500. RESULTS: Thirty-eight hemodialysis patients who died during the 6-year period had higher age, cardiothoracic ratio (CTR), CAVI, and haPWV, and lower diastolic blood pressure, albumin, phosphate, and calcium phosphate product. The Kaplan-Meier curves for cumulative survival among the tertile groups showed that the mortality rate was higher in the highest tertile (T3) compared to T1/T2 for both CAVI and haPWV. Receiver operating characteristic (ROC) analysis revealed that CAVI had better discriminatory power for all-cause mortality compared to haPWV. In the Cox-proportional hazards analyses, 1 SD increase in both parameters contributed independently to all-cause mortality [CAVI: HR 1.595 (95% CI 1.108-2.297), haPWV: HR 1.695 (95% CI 1.185-2.425)], as well as age and CTR. Both parameters above the cut-offs estimated in the ROC analysis (CAVI ≥ 9.2, haPWV ≥ 8.9) also had independent contributions to mortality. CONCLUSION: Through the 6 consecutive years of follow-up in 209 HD patients, increased CAVI might represent a major modifiable risk factor for all-cause mortality. Further research is needed to examine whether CAVI-lowering interventions contribute to improved prognosis.

Efficacy of environmental DNA to detect and quantify stream tadpoles of Odorrana splendida.

Environmental DNA (eDNA) can be used to detect and estimate the density of rare or secretive species, especially in aquatic systems. However, the efficacy of eDNA method has not been validated in lotic systems. We examined the efficacy of the eDNA method to detect and estimate abundance and biomass of a stream-dwelling frog species, Odorrana splendida. We conducted eight field surveys over 2 years and obtained 53 water samples from 10 streams with known distribution of O. splendida tadpoles. The eDNA method accurately detected the presence of O. splendida in 79.2% of survey samples. The amount of O. splendida eDNA (copies s-1) in the water samples fluctuated seasonally and each site showed different peaks during different seasons. The relationship between the abundance or biomass of tadpoles and the amount of eDNA was significantly positive, but was not strong, probably because of a large difference in the relationship patterns among streams. In lotic systems, water flow might prevent even distribution of eDNA and thus make it difficult to obtain eDNA reflecting its total amount in the water. Sampling a larger amount of water or higher number of subsamples might more accurately reflect the presence and absolute amount of eDNA in water.

[A clinical study on 106 infant cases who received detailed hearing tests after newborn hearing screening].

Newborn hearing screening (NHS) has been conducted widely in Japan in the last decade, however, there seems to be some confusion regarding the significance of NHS or management of the results obtained from NHS among clinics and practitioners. The system of NHS in Japan should be improved and refined through continuous evaluation of NHS, in terms of cost effectiveness in particular, so that NHS can be conducted more efficiently and effectively. To achieve this goal, the authors thought it important to clarify the current status and roles of our department as a facility for infants with congenital hearing impairment. In the present study, we studied 106 infant cases who were referred to the Department of Otolaryngology in Kyoto University Hospital after NHS before the age of twelve months in a period of seven years from 2006 to 2012 via retrospective chart reviewing. 79.2% of 96 infants who were qualified as referred either unilaterally or bilaterally following NHS were diagnosed as having hearing impairment in any form, either unilateral or bilateral, or conductive and/or sensorineural. The positive agreement rate was 88.7% in 53 cases who were qualified as referred bilaterally in NHS, demonstrating a high reliability of the NHS system. Twenty-four cases were diagnosed as having the need for hearing aids and were assigned to treatment and education. All the infants who underwent cochlear implantation in our department had severe bilateral hearing impairment of more than 105 dBnHL in both ears at the first examination. Moreover, a number of infants who were qualified as having passed in both ears in NHS or who had failed to receive NHS at birth were revealed as having hearing impairment and needed treatment later in the first year of their life, suggesting that NHS should be conducted in combination with periodical health checkups by family practitioners in order to identify infants with hearing impairment earlier in their life with higher efficacy.

Prey-tracking behavior in the invasive terrestrial planarian Platydemus manokwari (Platyhelminthes, Tricladida).

Platydemus manokwari is a broadly distributed invasive terrestrial flatworm that preys heavily on land snails and has been credited with the demise of numerous threatened island faunas. We examined whether P. manokwari tracks the mucus trails of land snail prey, investigated its ability to determine trail direction, and evaluated prey preference among various land snail species. A plastic treatment plate with the mucus trail of a single species and a control plate without the trail were placed side by side at the exit of cages housing P. manokwari. All trials were then videotaped overnight. The flatworms moved along plates with mucus trails, but did not respond to plates without trails, blank control (distilled water), or with conspecific flatworm trails. When presented at the midpoint of a snail mucus trail, the flatworms followed the trail in a random direction. The flatworms showed a preference when choosing between two plates, each with a mucus trail of different land snail species. Our results suggest that P. manokwari follows snail mucus trails based on chemical cues to increase the chance of encountering prey; however, trail-tracking behavior showed no directionality.

Development of the pseudothumb in frogs.

Frogs have highly conserved hand and foot morphology, possessing four fingers and five toes. As an exception, two Japanese ranid frog species, the Otton frog Babina subaspera and the dagger frog Babina holsti, possess a unique thumb-like structure (the pseudothumb) in the forelimb, giving an appearance of a total of five fingers on the hand. To obtain insights into the developmental mechanisms that generate this novel character, we investigated the hand morphogenesis of the Otton frog. The unique morphological pattern of the pseudothumb was already established in juveniles. Surprisingly, the bud-like structure, which is similar to the area of inductive activity (e.g. feather buds in birds and the carapacial ridge in turtles), was detected over the site where the future prepollex develops in larvae. By contrast, this bud-like structure was not found in larvae of other ranid species. We discuss possible scenarios that would favour the evolution of this very unusual trait in frogs.

Positive indirect effect of tadpoles on a detritivore through nutrient regeneration.

In aquatic food webs consumers can affect other members of the web by releasing nutrients as a result of their feeding activity. There is increasing evidence of these positive effects on primary producers, but such nutrient regeneration can also affect detritivores, by favoring the activities of detritus-associated microbes. We examined the effects of nutrient regeneration by tadpoles on leaf-eating detritivores under laboratory conditions. We fed four species of tadpoles three different food items (leaf litter, algae, and sludgeworms). We then conditioned terrestrial dead leaves with water from reared tadpoles (treatments) or food items alone (controls), and compared the C:N ratios of the conditioned leaves and the growth of the isopod Asellus hilgendorfii fed on the conditioned leaves. Tadpole feeding activity reduced the C:N ratio of conditioned leaves, and the effect was greatest when tadpoles were fed algae. Isopod growth rates were often higher when they were fed the litter conditioned with water from reared tadpoles. Thus, nutrient regeneration by tadpoles had a positive indirect effect on detritivores by enhancing leaf quality. Tadpoles often occur in nutrient-limited habitats where leaf litter is the major energy source, and their facilitative effects on leaf-eating detritivores may be of great significance in food webs by enhancing litter decomposition.