Spatial aggregation patterns in four mistletoe species: ecological and environmental determinants

Plant spatial distribution is an important topic in ecology as it determines species coexistence and biodiversity dynamics. Usually, plants show clustered distributions in nature. Mistletoes are a good example of aggregated distributions, as they form dense aggregations due to several factors (availability of competent hosts, seed dispersal vectors, microclimate conditions). We analysed four native mistletoe species with divergent life histories and host ranges: Desmaria mutabilis and Tristerix corymbosus from the temperate rainforests of southern Chile; and Tristerix aphyllus and Tristerix verticillatus from the northern semi-desert zone. While T. corymbosus and T. verticillatus have a wide host range, T. aphyllus and D. mutabilis are specialists that can parasitize only a few plant species. We hypothesized that specialized species would be more aggregated due to ecological and environmental restrictions. We used heterogeneous Poisson models to quantify spatial aggregation. Three of the four mistletoe species were spatially clustered at both environments, with aggregation being stronger in the temperate rainforest of southern Chile and particularly in the host-specialist species. Our results suggest that environmental constraints are more important than ecological constraints (host range) in shaping mistletoe spatial structure. Mistletoe aggregated spatial distribution depends primarily on the environment that they inhabit, which conditions host spatial availability, and arrangement.

Absolute Reliability and Concurrent Validity of Hand-Held Dynamometry in Shoulder Rotator Strength Assessment: Systematic Review and Meta-Analysis

The purpose of this study is to establish the absolute reliability between hand-held dynamometers (HHDs) and concurrent validity between HHDs and isokinetic dynamometers (IDs) in shoulder rotator strength assessment. The Medline, CINAHL, and Central databases were searched for relevant studies up to July 2020. Absolute reliability was determined by test–retest studies presenting standard error of measurement (SEM%) and/or minimal detectable change (MDC%) expressed as percentage of the mean. Studies considering intra-class correlation coefficient (ICC) between IDs and HHDs were considered for concurrent validity. The risk of bias and the methodological quality were evaluated according to COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN). Thirteen studies were included in the meta-analysis. Shoulder internal rotator strength assessment MDC% was 0.78%, 95% confidence interval (CI) −5.21 to 3.66, while shoulder external rotators MDC% was 3.29%, CI −2.69 to 9.27. ICC between devices was 0.94, CI (0.91 to 0.96) for shoulder internal rotators and 0.92, IC (0.88 to 0.97) for shoulder external rotators. Very high correlation was found for shoulder rotator torque assessment between HHDs and IDs. The COSMIN checklist classified the selected studies as adequate and inadequate.

International Child Care Practices Study: infant sleeping environment

BACKGROUND

The International Child Care Practices Study (ICCPS) has collected descriptive data from 21 centres in 17 countries. In this report, data are presented on the infant sleeping environment with the main focus being sudden infant death syndrome (SIDS) risk factors (bedsharing and infant using a pillow) and protective factors (infant sharing a room with adult) that are not yet well established in the literature.

METHODS

Using a standardised protocol, parents of infants were surveyed at birth by interview and at 3 months of age mainly by postal questionnaire. Centres were grouped according to geographic location. Also indicated was the level of SIDS awareness in the community, i.e. whether any campaigns or messages to "reduce the risks of SIDS" were available at the time of the survey.

RESULTS

Birth interview data were available for 5488 individual families and 4656 (85%) returned questionnaires at 3 months. Rates of bedsharing varied considerably (2-88%) and it appeared to be more common in the samples with a lower awareness of SIDS, but not necessarily a high SIDS rate. Countries with higher rates of bedsharing appeared to have a greater proportion of infants bedsharing for a longer duration (>5 h). Rates of room sharing varied (58-100%) with some of the lowest rates noted in centres with a higher awareness of SIDS. Rates of pillow use ranged from 4% to 95%.

CONCLUSIONS

It is likely that methods of bedsharing differ cross-culturally, and although further details were sought on different bedsharing practices, it was not possible to build up a composite picture of "typical" bedsharing practices in these different communities. These data highlight interesting patterns in child care in these diverse populations. Although these results should not be used to imply that any particular child care practice either increases or decreases the risk of SIDS, these findings should help to inject caution into the process of developing SIDS prevention campaigns for non-Western cultures.

[Female physicians: work and family]

One hundred female physicians were surveyed to describe features of their family, social and academic lives and obstetric history. Most outstanding findings were that 8% of women were divorced or separated, a trend to have few children and a mean day's work of 9.2 hour. Sixteen percent of women had a history of premature delivery and 22% premature labour symptoms (higher than the frequency found in the general population). Mean age at first childbirth was 26 years, significantly higher than the average of the general population (22.8 years). Prenatal leave was partially or not used by 50% of women, while postnatal leave was not benefitted by 12%. Breast feeding had a mean lapse of 3.8 months (shorter than advised). Sixty seven percent of women found scarce the length of time devoted to their children and 67% felt satisfied with their mate relationship. Fifty three percent performed 4 or more spare time activities a month and 55% declared to be satisfied with their professional performance. A mean of 0.89 scientific papers/year/woman were published or presented to meeting. Thirty percent believed that their professional work had a negative impact on their family life.

[Unwanted children: incidence and characteristics among puerperal women in a hospital of Santiago]

A scoring instrument to detect unwanted newborns was applied to 556 living-in women at a Santiago urban hospital in december 1987. Based upon previous research a scoring instrument including 10 items was designed and applied within 24 hours following delivery. According to the total score each newborn was classified as wanted (W), unwanted (U) or doubtful situation: 37.6% of children were born to unwed mothers. In a total of 556 children 4.5% (n = 25) were classified as U, 91.4% as W (n = 508) and 4.1% as doubtful (n = 23). Comparing U and W children the former had mothers with poorer education, higher frequency of bad relationships with their partners as well as higher proportion of three or more previous deliveries and late beginning of prenatal care (significant). On the other hand no significant differences were detected in age distribution of the mothers or their socio-economic level. The applicability of this scoring system and the magnitude and importance of the problem are analyzed and discussed. The need for further research on the natural history of the sequence unwanted pregnancy-unwanted child is stressed.

Pharmacokinetics and bioavailability of a controlled release amoxicillin formulation

The pharmacokinetics and bioavailability of an in vitro controlled release amoxicillin formulation were studied in nine healthy volunteers, in comparison with an intravenous injection and a conventional tablet. The experiment was designed in a crossover fashion. The volunteers received the three formulations on separate occasions. The antibiotic was measured in plasma using a microbiological method. The absolute bioavailability of the two solid dosage forms was estimated comparing non-compartmental parameters. The results indicated that there was no correlation between the in vitro dissolution rate and the pharmacokinetic behavior in the body.

Studies on aminoacyl tRNA synthetases and transfer RNA in living Xenopus laevis oocytes

The microinjection of transfer RNA into amphibian oocytes permits one to study under in vivo conditions the reactions that affect this important macromolecule. A comparative study has been carried out between the in vivo and in vitro specificity of the aminoacylation reacton. The results obtained show that modifications of the tRNA structure affect aminoacyl-tRNA synthetase recognition in the same fashion in both conditions. The in vivo aminoacylation was not affected by the presence of puromycin (0.5mM) or cycloheximide (0.1 mM) which completely inhibited oocyte protein synthesis. An interesting difference was obtained between the in vivo and in vitro aminoacylation of tRNA with regards to temperature requirements. While the in vivo reaction was optimal at 25 degrees and was totally inhibited at 37 degrees, the in vitro was optimal, at the latter temperature. The inhibition of the in vivo reaction at 37 degrees was not due to inactivation of the enzyme. The transfer of the amino acid moiety to nascent proteins was studied by measuring the transfer of radioactivity from injected (14C) phenylalanyl-tRNA into hot trichloroacetic acid precipitable material. It was found that 30% or more of the amino acid became incorporated into oocyte proteins and that this incorporation was due to direct transfer from the aminoacyl-tRNA and was inhibited by puromycin and cycloheximide.