First Detection of Acinetobacter baumannii in Pediculus humanus capitis from Latin America

Several studies have documented the presence of Acinetobacter baumannii, a known multi-drug-resistant pathogen, in the human head louse, Pediculus humanus capitis. Since no reports from countries in Latin America have been published, the aim of the present study was to determine whether A. baumannii was present in head lice specimens collected in this geographic region. Head lice specimens from Argentina, Colombia, and Honduras were analyzed. PCR assays were performed to confirm the specimens' species and to investigate whether the DNA of A. baumannii was present. The products of the latter were sequenced to confirm bacterial identity. Altogether, 122 pools of head lice were analyzed, of which two (1.64%) were positive for A. baumannii's DNA. The positive head lice had been collected at the poorest study site in Honduras. The remaining specimens were negative. This study is the first to report the presence of A. baumannii in human head lice from Latin America. Further investigations are required to elucidate whether these ectoparasites can serve as natural reservoirs or even effectively transmit A. baumannii to humans.

Race- and sex-based variation in industry research and general payments to medical oncologists in the United States

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Background: Industry partnerships offer financial incentives, prestige, and can facilitate career advancement in oncology. However, not all physicians may have equal access to these opportunities. We hypothesized that physicians who are underrepresented in the medical oncology workforce based on race, ethnicity, and gender receive less industry funding. Methods: All US medical oncologists (MOs) who received ≥1 industry research payment between 2016 and 2020 according to the Open Payments database were included in this retrospective study. Information extracted from Open Payments included MO’s name, institution, research payments (i.e. funding for a research project where the physician is a Principle Investigator), and general payments (i.e. fees not associated with research, such as consulting and travel fees). Additional web searches were conducted using institutional websites, NPPES NPI registry, LinkedIn, Doximity, Scopus, and NIH RePORTER to determine each MO’s race, ethnicity, sex, academic rank, degrees, h-index, institutional NIH research funding rank, and individual receipt of NIH funding. Log-linear regression was performed to identify associations of both industry and general payment data. Results: Of 7,542 physicians meeting inclusion criteria, 69% were male, 65% White, 29% Asian, 2% Black, and 4% Hispanic, which is comparable to the American Medical Association Physician Masterfile figures for MO. The median sum research payment and general payment was $134,857 and $11,537 per physician respectively. Significantly higher mean research payments were associated with an MS (+72%; P = 0.003) or PhD degree (+30%; P = 0.009), h-index (+3%; P < 0.001), top 50 institution rank by NIH funding (+44%; P < 0.001), and associate professor rank (+95%; P < 0.001). Significantly lower mean research payment were observed for Black physicians (-36%; P = 0.022) and those with non-academic affiliation (-47%; P < 0.001). No significant association was observed between sex and research payment. Significantly higher mean general payments were associated with male sex (+46%; P < 0.001), MS degree (+171%; P < 0.001), h-index (+2%; P < 0.001), and Asian race (+72%; P < 0.001). Significantly lower mean general payments were associated with an affiliation with a non-academic practice (-31%; P = 0.012). Conclusions: Black physicians received smaller sums of industry research payments compared to White physicians. Female sex was associated with decreased general payments compared to male sex. Further exploring the underlying mechanisms determining access to industry payments may help facilitate greater equity and inclusivity in oncology.

First evidence of the mutations associated with pyrethroid resistance in head lice (Phthiraptera: Pediculidae) from Honduras

Background

The human head louse, Pediculus humanus capitis, is a cosmopolitan blood-sucking ectoparasite affecting mostly schoolchildren in both developed and developing countries. In Honduras, chemical pediculicides are the first line of treatment, with permethrin as their main active ingredient. Despite the extended use of these products, there is currently no research investigating insecticide resistance in Honduran head lice. In head lice, the most common mechanism is knockdown resistance (kdr), which is the result of two point mutations and the associated amino acid substitutions, T917I and L920F, within the voltage-sensitive sodium channel (VSSC).

Methods

Genomic DNA was extracted from 83 head lice collected in the localities of San Buenaventura and La Hicaca, Honduras. Polymerase chain reaction (PCR) was used to amplify a 332-bp fragment of the VSSC gene that contains a site affected by C/T mutation which results in a T917I amino acid substitution on each human head louse genomic DNA fragments.

Results

The C/T non-synonymous mutation which results in the T917I kdr amino acid substitution was detected in both head lice populations at frequencies ranging between 0.45–0.5. Globally, the frequency of this substitution was 0.47. Of these, 5 (6.1%) were homozygous susceptible and 78 (93.9%) were heterozygotes. The kdr-resistant homozygote (RR) was not detected in the studied populations. Thus, 93.9% of the head lice collected in Honduras harbored only one T917I allele. Exact test for the Hardy-Weinberg equilibrium for both localities showed that genotype frequencies differed significantly from expectation. In addition, San Buenaventura and La Hicaca populations had an inbreeding coefficient (F_is) < 0, suggesting an excess of heterozygotes.

Conclusions

To our knowledge, this is the first study showing the presence of the C/T mutation responsible of the T917I kdr allele associated with pyrethroid resistance in P. h. capitis from Honduras. The PCR-restriction fragment length polymorphism (RFLP) employed here has demonstrated to be a reliable, economic, and reproducible assay that can be used to accurately genotype individual head lice for the mutation encoding the resistance-conferring T917I amino acid substitution. This highlights the necessity of proactive resistance management programmes designed to detect pyrethroid mutations before they become established within populations of head lice.

Knowledge of Australian primary education providers towards dental avulsion injuries: a cross-sectional study

BACKGROUND/AIM

The aim of this study was to evaluate the knowledge of school professionals regarding the emergency management of dental avulsion.

METHODS

This cross-sectional study utilised a self-administered, pilot-tested questionnaire for school staff from primary schools. Descriptive statistics were used for the analysis - the prevalence and univariate associations between a categorical outcome and the variables under consideration, were evaluated using Pearson's Chi-squared test.

RESULTS

This survey yielded a response rate of 43.5% (n = 313). Approximately 60% of participants held valid first-aid certificates and 23% had received avulsion advice previously. Over 80% of participants expressed an unwillingness to replant an avulsed tooth, and over 90% believed that there should be greater awareness in this area. This unwillingness to replant was influenced by respondents' age (x2 = 8.13 df = 3, P = 0.043) and receiving advice previously (x2 = 13.15, df = 1, P < 0.001). Under-preparedness was related to years of experience (x2 = 15.03, df = 5, P = 0.010), first-aid training (x2 = 6.41, df = 1, P = 0.011) and receiving advice previously (x2 = 43.47, df = 1, P < 0.001). It was also evident that first-aid training positively influenced appropriate dental referral in the management pathway (x2 = 10.49, df = 1, P = 0.001).

CONCLUSION

This study suggests that there is an inadequate level of knowledge on the appropriate management of dental avulsion injuries amongst primary school professionals in Australia.

Restricting oxygen supply to the prospective dorsal side does not reverse axis polarity in embryos of Xenopus laevis

During the first cell cycle, the prospective dorsal side of the embryo of Xenopus laevis becomes enriched in mitochondria relative to the ventral side. This differential distribution of mitochondria persists throughout early development, but it is not known if it is of functional significance, since there do not appear to be dorsal-ventral differences in metabolic rate. However, the unilateral anaerobiosis experiments of Landström and Løvtrup do suggest a role for energy metabolism in determining axis polarity. These experiments apparently show that restricting oxygen supply to the prospective dorsal side causes a reversal of dorsal-ventral axis polarity. We have reinvestigated this point using cell-marking techniques. We find that although gastrulation is initiated at the open end of the tube, the polarity of neural plate development is unaffected. Thus, definitive dorsal-ventral polarity is not affected by the experimental treatment, and it is unlikely that gradients of energy metabolism have a role in specifying axis polarity in X. laevis.

Male offspring production by asexual Potamopyrgus antipodarum, a New Zealand snail

As only females contribute directly to population growth, sexual females investing equally in sons and daughters experience a two-fold cost relative to asexuals producing only daughters. Typically, researchers have focused on benefits of sex that can counter this 'cost of males' and thus explain its predominance. Here, we instead ask whether asexuals might also pay a cost of males by quantifying the rate of son production in 45 experimental populations ('lineages') founded by obligately asexual female Potamopyrgus antipodarum. This New Zealand snail is a powerful model for studying sex because phenotypically similar sexual and asexual forms often coexist, allowing direct comparisons between sexuals and asexuals. After 2 years of culture, 23 of the 45 lineages had produced males, demonstrating that asexual P. antipodarum can make sons. We used maximum-likelihood analysis of a model of male production in which only some lineages can produce males to estimate that ~50% of lineages have the ability to produce males and that ~5% of the offspring of male-producing lineages are male. Lineages producing males in the first year of the experiment were more likely to make males in the second, suggesting that some asexual lineages might pay a cost of males relative to other asexual lineages. Finally, we used a simple deterministic model of population dynamics to evaluate how male production affects the rate of invasion of an asexual lineage into a sexual population, and found that the estimated rate of male production by asexual P. antipodarum is too low to influence invasion dynamics.

Myotonic dystrophy--a multigene disorder

Myotonic dystrophy (DM1) is the most common form of adult muscular dystrophy with an estimated incidence of 1/8000 births. The mutation responsible for this condition is an expanded CTG repeat within the 3' untranslated region of the protein kinase gene DMPK. Strong nucleosome positioning signals created by this expanded repeat cause a reduction in gene expression within the region. This "field effect" is further confounded by the retention of DMPK expansion containing transcripts, which acquire a toxic gain of function. Thus, the various manifestations exhibited by DM1 patients can be explained as a result of gene silencing, nuclear retention and sequestration of nuclear factors by the CUG containing transcript.

A self-calibrating phase-shifting algorithm based on the natural demodulation of two-dimensional fringe patterns

A new method of estimating the phase-shift between interferograms is introduced. The method is based on a recently introduced two-dimensional Fourier-Hilbert demodulation technique. Three or more interferogram frames in an arbitrary sequence are required. The first stage of the algorithm calculates frame differences to remove the fringe pattern offset; allowing increased fringe modulation. The second stage is spatial demodulation to estimate the analytic image for each frame difference. The third stage robustly estimates the inter-frame phase-shifts and then uses the generalised phase-shifting algorithm of Lai and Yatagai to extract the offset, the modulation and the phase exactly. Initial simulations of the method indicate that high accuracy phase estimates are obtainable even in the presence of closed or discontinuous fringe patterns.

In vivo co-localisation of MBNL protein with DMPK expanded-repeat transcripts

Myotonic dystrophy (DM1) is the most common form of adult muscular dystrophy and is inherited as an autosomal dominant trait. The genetic basis of DM1 is the expansion of a CTG repeat in the 3' untranslated region of a protein kinase gene (DMPK). The molecular mechanism by which this expanded repeat produces the pathophysiology of DM1 remains unknown. Transcripts from the expanded allele accumulate as foci in the nucleus of DM1 cells and it has been suggested that these transcript foci sequester cellular proteins that are required for normal nuclear function. We have investigated the role of three RNA-binding proteins, CUG-BP, hnRNP C and MBNL, as possible sequestered factors. Using a combination of indirect immunofluorescence to detect endogenous proteins and overexpression of proteins with green fluorescent protein (GFP) tags we have shown that CUG-BP and hnRNP C do not co-localise with expanded repeat foci in DM1 cell lines. However, GFP-tagged MBNL does itself form foci in DM1 cell lines and co-localises with the foci of expanded repeat transcripts. GFP-tagged MBNL does not appear as foci in non-DM1 cell lines. This work provides further support for the involvement of MBNL in DM1.

Three-dimensional Analysis of Laser Scanning Confocal Microscope Sections Reveals an Array of Microtubules in the Cleavage Furrow of Sea Urchin Eggs

Our recent observation that microtubules (MTs) are required for completion of division (abscission) led us to analyze MT organization during cytokinesis. Although many studies of MTs in sea urchin eggs have been done, computer-aided analysis of optical sections described herein reveals a new MT assemblage, which we call furrow MTs. This assemblage comprises bundles of MTs that lie in the cleavage furrow. Furrow MTs become apparent when the furrow has progressed approximately one-third of the way through the egg and persist to abscission. Furrow MTs are 8-24-&mgr;m long and arc across the base of the cleavage furrow. Acetylated tubulin is localized primarily in the furrow suggesting a distinct MT population. Three-dimensional analysis of optical sections suggests that furrow MTs are spatially distinct from midbody and astral MTs.

Ventral cell rearrangements contribute to anterior-posterior axis lengthening between neurula and tailbud stages in Xenopus laevis

Studies of morphogenesis in early Xenopus embryos have focused primarily on gastrulation and neurulation. Immediately following these stages is another period of intense morphogenetic activity, the neurula-to-tailbud transition. During this period the embryo is transformed from the spherical shape of the early stages into the long, thin shape of the tailbud stages. While gastrulation and neurulation depend largely on active cell rearrangement and cell shape changes in dorsal tissues, we find that the neurula-to-tailbud transition depends in part on activities of ventral cells. Ventral explants of neurula lengthen autonomously as much as the ventral sides of intact embryos, while dorsal explants lengthen less than the dorsal sides of intact embryos. Analyses of cell division, cell shapes, and cell rearrangement by transplantation of labeled cells and by time lapse recordings in live intact embryos concur that cell rearrangements in ventral mesoderm and ectoderm contribute to the autonomous anterior-posterior axis lengthening of ventral explants between neurula and tailbud stages.

Microtubules are required for completion of cytokinesis in sea urchin eggs

Completion of cytokinesis, abscission, has been studied little despite the intensive studies of the onset and contractile mechanism of the earlier phases of division. It has been well documented that microtubule (MT) disruption before furrow stimulation prevents furrowing, while MT disruption after furrow stimulation allows division to proceed. We have confirmed those findings using the MT inhibitors, nocodazole and demecolcine. In addition, we have found that MT disruption after furrow stimulation but before completion of division prevents abscission as evidenced by the observation that prospective daughter cells in MT-disrupted eggs maintain electrical continuity. Continued observation of eggs revealed that the furrow in MT-disrupted eggs did not result in abscission, but rather held steady until the time when controls underwent second cleavage, at which point the furrows regressed. These findings extend the recent reports that MTs are required for completion of division in mammalian tissue culture cells and frog eggs, to invertebrates, suggesting a common mechanism of abscission for animal cells.

Development of a yeast-based assay system for monitoring microsatellite instability

Simple sequence repeats (microsatellites) are found in all eukaryotic genomes. Instabilities within these sequences have been associated with several human disorders including Huntington's chorea and myotonic dystrophy. Further studies have identified links between microsatellite instability, faulty mismatch repair and certain human cancers, in particular a form of hereditary colorectal cancer. The assay system described here consists of a congenic set of yeast strains mutated in DNA replication and mismatch repair genes and assay plasmids with which it is possible to measure differences in microsatellite stability in the range of 5-850-fold. The development of this technology will allow monitoring of environmental and dietary influences on the genomic stability in the context of human disease.

Metal binding to the HIV nucleocapsid peptide

Co(II) and Zn(II) binding constants have been measured for binding to the HIV-1 nucleocapsid N-terminal metal binding domain (residues 1-18), using competition titration methods and monitoring Co(II) binding by visible absorbance spectroscopy. Enthalpies for binding were directly measured by isothermal titration colorimetry. The results are compared with recent studies of related systems, including a study of Zn(II) binding by the full length protein.

Requirement for microtubules in new membrane formation during cytokinesis of Xenopus embryos

In cleaving Xenopus eggs, exposure to nocodazole or cold shock prevents the addition of new plasma membrane to the cleavage plane and causes furrows to recede, suggesting a specific role for microtubules in cytokinesis. Whole-mount confocal immunocytochemistry reveals a ring of radially arranged, acetylated microtubule bundles at the base of all advancing cleavage furrows, from the first cleavage through the midblastula stage. We hypothesize that this novel microtubular structure is involved in transporting maternal stores of membrane in the subcortex to a site of membrane addition near the leading edge of the furrow.

Five newly established oesophageal carcinoma cell lines: phenotypic and immunological characterization

The derivation of permanent cell lines from 40 resected oesophageal carcinomas has been attempted. Five long-term lines have been established from three adenocarcinomas, one mixed carcinoma and one squamous carcinoma. Molecular and cellular analyses have been carried out on the lines and clones derived from them. Karyotype analysis indicates genetic variation among the clones. HLA-A, -B and -C is expressed constitutively, but not HLA-DR. ICAM-1-expressing phenotypes may have arisen during adaptation to long-term culture. All lines are capable of response to interferon-gamma (IFN-gamma) and all produce transforming growth factor beta 1 (TGF-beta 1). Two lines are resistant to the inhibitory growth effects of the latter, possibly contributing to malignancy. It is anticipated that these lines, originating from histologically different carcinomas, will provide a valuable, continuous resource for the investigation and treatment of these aggressive tumours.

Regulative development of Xenopus laevis in microgravity

To test whether gravity is required for normal amphibian development, Xenopus laevis females were induced to ovulate aboard the orbiting Space Shuttle. Eggs were fertilized in vitro, and although early embryonic stages showed some abnormalities, the embryos were able to regulate and produce nearly normal larvae. These results demonstrate for the first time that a vertebrate can ovulate in the virtual absence of gravity, and that the eggs can develop to a free-living stage.

Emotional and cardiovascular responses to adults' angry behavior and to challenging tasks in children of hypertensive and normotensive parents

Cardiovascular, overt-motor, and verbal-reported responses to interadult emotional expressions, including anger, and to challenging task situations were examined in a sample of 49 10-14-year-old children of hypertensive (EH) and normotensive parents (NT). Sons of EH parents showed greater systolic blood pressure reactivity to interadult anger and to the digit span task than sons of NT parents. A consistent pattern was not found for girls. Marital distress and overt maternal anger expression predicted verbal-reported and overt-motor responses to interadult anger. Family history of EH and sex did not predict these responses. Implications include (a) heightened systolic blood pressure response to stress may be found in sons of EH parents before they are diagnosed to have EH disorders, (b) relations between family history of EH and cardiovascular response may be sex moderated, and (c) vulnerability to stress may be related to specific familial histories and backgrounds.

Competence and stress in school children: the moderating effects of individual and family qualities

This study examined the associations of stress exposure to various aspects of school-based competence in a normative sample of 205 children aged 8-13. Potential moderators of these relations, including child attributes of sex and IQ and environmental attributes of socioeconomic status (SES) and family qualities, were also studied. Stress exposure was indexed by a life event questionnaire. Competence was assessed by teacher ratings, peer assessments and school record data. Family attributes were derived from a set of rating scales completed by interviewers after 6 hours of interviews with a parent. Results suggest that the relations of stress exposure to competence vary as a function of individual differences as well as the competence criterion. Disadvantaged children, with lower IQ and SES, and less positive family qualities, were generally less competent and more likely to be disruptive at high stress levels. Advantaged children were more competent, and with stress positively engaged in school, but were not likely to be disruptive. Boys were less socially competent than girls and, when stress was high, appeared to be less protected by positive family qualities. Causal hypotheses for future research in this area are discussed.