Accreting protoplanets in the LkCa 15 transition disk.

Exoplanet detections have revolutionized astronomy, offering new insights into solar system architecture and planet demographics. While nearly 1,900 exoplanets have now been discovered and confirmed, none are still in the process of formation. Transition disks, protoplanetary disks with inner clearings best explained by the influence of accreting planets, are natural laboratories for the study of planet formation. Some transition disks show evidence for the presence of young planets in the form of disk asymmetries or infrared sources detected within their clearings, as in the case of LkCa 15 (refs 8, 9). Attempts to observe directly signatures of accretion onto protoplanets have hitherto proven unsuccessful. Here we report adaptive optics observations of LkCa 15 that probe within the disk clearing. With accurate source positions over multiple epochs spanning 2009-2015, we infer the presence of multiple companions on Keplerian orbits. We directly detect Hα emission from the innermost companion, LkCa 15 b, evincing hot (about 10,000 kelvin) gas falling deep into the potential well of an accreting protoplanet.

Water vapour and hydrogen in the terrestrial-planet-forming region of a protoplanetary disk.

Planetary systems (ours included) formed in disks of dust and gas around young stars. Disks are an integral part of the star and planet formation process, and knowledge of the distribution and temperature of inner-disk material is crucial for understanding terrestrial planet formation, giant planet migration, and accretion onto the central star. Although the inner regions of protoplanetary disks in nearby star-forming regions subtend only a few nano-radians, near-infrared interferometry has recently enabled the spatial resolution of these terrestrial zones. Most observations have probed only dust, which typically dominates the near-infrared emission. Here I report spectrally dispersed near-infrared interferometric observations that probe the gas (which dominates the mass and dynamics of the inner disk), in addition to the dust, within one astronomical unit (1 au, the Sun-Earth distance) of the young star MWC 480. I resolve gas, including water vapour and atomic hydrogen, interior to the edge of the dust disk; this contrasts with results of previous spectrally dispersed interferometry observations. Interactions of this accreting gas with migrating planets may lead to short-period exoplanets like those detected around main-sequence stars. The observed water vapour is probably produced by the sublimation of migrating icy bodies, and provides a potential reservoir of water for terrestrial planets.

Rare incidence of cholecystocolonic fistula and robotic-assisted surgical management.

We present a patient who was found to have a cholecystocolonic fistula during robotic cholecystectomy. The patient initially presented with Non-ST-elevation myocardial infarction (NSTEMI) and biliary obstruction. A delayed cholecystectomy was performed robotically after managing his Coronary Artery Disease (CAD) and relief of his biliary obstruction with endoscopic retrograde cholangiopancreatography (ERCP). Intraoperatively, a cholecystocolonic fistula, was found. This case report aims to highlight intraoperative management of the fistula and review the existing literature.

Sperm-dependent parthenogens delay the spatial expansion of their sexual hosts.

It has been known for long time that asexual organisms may affect the distribution of sexual taxa. In fact, such phenomenon is inherent in the concept of geographical parthenogenesis. On the other hand, it was generally hypothesized that sperm-dependent asexuals may not exercise the same effect on related sexual population, due to their dependence upon them as sperm-donors. Recently, however, it became clear that sperm-dependent asexuals may directly or indirectly affect the distribution of their sperm-hosts, but rather in a small scale. No study addressed the large-scale biogeographic effect of the coexistence of such asexuals with the sexual species. In our study we were interested in the effect of sexual-asexual coexistence on the speed of spatial expansion of the whole complex. We expand previously published Lotka-Volterra model of the coexistence of sexual and gynogenetic forms of spined loach (Cobitis; Teleostei) hybrid complex by diffusion. We show that presence of sperm-dependent parthenogens is likely to negatively affect the spatial expansion of sexuals, and hence the whole complex, compared to pure sexual population. Given that most of the known sperm-dependent asexual complexes are distributed in areas prone to climate-induced colonization/extinction events, we conclude that such mechanism may be an important agent in determining the biogeography of sexual taxa and therefore requires further attention including empirical tests.

A limited number of Caenorhabditis elegans genes are readily mutable to dominant, temperature-sensitive maternal-effect embryonic lethality.

Dominant gain-of-function mutations can give unique insights into the study of gene function. In addition, gain-of-function mutations, unlike loss-of-function alleles, are not biased against the identification of genetically redundant loci. To identify novel genetic functions active during Caenorhabditis elegans embryogenesis, we have collected a set of dominant temperature-sensitive maternal-effect embryonic lethal mutations. In a previous screen, we isolated eight such mutations, distributed among six genes. In the present study, we describe eight new dominant mutations that identify only three additional genes, yielding a total of 16 dominant mutations found in nine genes. Therefore, it appears that a limited number of C. elegans genes mutate to this phenotype at appreciable frequencies. Five of the genes that we identified by dominant mutations have loss-of-function alleles. Two of these genes may lack loss-of-function phenotypes, indicating that they are nonessential and so may represent redundant loci. Loss-of-function mutations of three other genes are associated with recessive lethality, indicating nonredundancy.

Insights into the development of polycystic ovary syndrome (PCOS) from studies of prenatally androgenized female rhesus monkeys.

The developmental pathophysiology of polycystic ovary syndrome (PCOS) is unknown. However, prenatally androgenized female rhesus monkeys exhibit ovarian and endocrinological features that mimic those found in women with PCOS. Thus, prenatal androgen excess may provide an etiology for hyperandrogenism and anovulation in adulthood.

Timing of prenatal androgen excess determines differential impairment in insulin secretion and action in adult female rhesus monkeys.

This study determined whether timing of prenatal androgen excess resulted in differential impairment of insulin-glucose homeostasis in adult female rhesus monkeys. Ten female rhesus monkeys exposed to testosterone propionate starting on gestational day 40 (early treated), 9 females exposed to testosterone propionate starting between gestational days 100-115 (late treated), and 15 control females were studied. The modified minimal model was used to examine various measures derived from an i.v. glucose tolerance test, with regression analysis performed between these variables and body mass index. In addition, the disposition index (DI) and the hyperbolic relationship between insulin sensitivity (S(I)) and acute insulin response to glucose were examined. Early treated females demonstrated impaired pancreatic beta-cell function, as shown by diminished DI and decreased percentile ranking for the hyperbolic relationship between S(I) and acute insulin response to glucose. In contrast, late treated females exhibited both an increase in DI and a negative relationship between body mass index and S(I). These results suggest that prenatal androgen excess in female rhesus monkeys, regardless of gestational timing, perturbs insulin-glucose homeodynamics, with androgen excess in early and late gestation impairing pancreatic beta-cell function and altering insulin sensitivity, respectively.

Anticoagulant activity of Hirulog, a direct thrombin inhibitor, in humans.

Hirulog (BG8967) is a direct thrombin inhibitor built by rational design using the protein hirudin as a model (Maraganore et al. [1990]; Biochemistry 29: 7095-101). In order to evaluate the therapeutic potential for hirulog in the management of thrombotic disease, the tolerability and anticoagulant activity of the agent were examined in a study of human volunteers. In a randomized, placebo-controlled study (n = .54), the intravenous infusion of hirulog over 15 min showed a rapid, dose-dependent prolongation of activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). There was a corresponding dose-dependent increase in plasma hirulog levels. The peptide was rapidly cleared with a half-life of 36 min and a total body clearance rate for the peptide of 0.43 l kg-1 h-1. Similar activity was observed following subcutaneous injection but with sustained pharmacodynamic and pharmacokinetic behavior. There was a significant correlation between pharmacokinetic and pharmacodynamic variables for both intravenous (r = 0.8, p < 0.001) and subcutaneous administration (r = 0.7, p = 0.002). To evaluate the possible interactions of aspirin on the tolerability and anticoagulant activity of intravenous hirulog, a cross-over design was employed in eight subjects. Aspirin administration did not modify the peptide's activity. At the administered dose of 0.6 mg kg-1 h-1 for 2 h, hirulog infusion prolonged APTT from 230 to 260% baseline. The infusion of hirulog in subjects who had received aspirin was not associated with any significant changes in the template bleeding time.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal exposure of female rhesus monkeys to testosterone propionate increases serum luteinizing hormone levels in adulthood.

OBJECTIVE: To determine whether prenatal androgenization of the developing primate hypothalamohypophyseal unit induces irreversible changes in LH secretion. DESIGN: Prospective nonrandomized study. SETTING: An academic research environment. ANIMALS: Forty-one adult ovulatory female rhesus monkeys. INTERVENTION(S): Seventeen female rhesus monkeys exposed prenatally to testosterone propionate (female pseudohermaphrodites) and 24 normal females underwent blood sampling over two ovulatory menstrual cycles. MAIN OUTCOME MEASURE(S): Serum FSH, LH, E2, and T were determined by RIA; P was determined by enzyme immunoassay. Serum bioactive LH was measured by mouse Leydig cell bioassay. RESULT(S): Tonic immunoactive LH hypersecretion and normal FSH release occurred in female pseudohermaphrodites compared with normal females. Periovulatory immunoactive LH and FSH secretion was similar in both female types, whereas a relative increase in the amount of circulating bioactive LH to immunoactive LH was found at midcycle in female pseudohermaphrodites versus normal females. The length of the follicular phase was unaffected by prenatal androgen exposure, but the slopes of serum T and E2 concentrations versus follicular phase cycle day were significantly lower in female pseudohermaphrodites than normal females. Luteal phase length and P secretion were comparable in both types of females. CONCLUSION(S): Androgen exposure during primate neural differentiation may alter permanently the pattern of LH secretion in the presence of cyclic gonadotropin release.

Insulin action during variable hyperglycemic-hyperinsulinemic infusions in hyperandrogenic anovulatory patients and healthy women.

OBJECTIVE: To determine whether 3-month GnRH analogue (GnRH-a) administration to hyperandrogenic anovulatory patients and healthy women affects glucose utilization or endogenous glucose production (EGP) in the postabsorptive state and during variable hyperglycemic-hyperinsulinemic infusions. DESIGN: Prospective, nonrandomized study. SETTING: Academic research environment. PATIENT(S): Twelve hyperandrogenic anovulatory patients and 11 healthy women matched by body mass index and waist to hip circumference ratio. INTERVENTION(S): Variable hyperglycemic-hyperinsulinemic infusions replicated physiological increases in circulating glucose and insulin levels before and after 3-month GnRH-a administration. MAIN OUTCOME MEASURE(S): Glucose utilization and EGP. RESULT(S): In the postabsorptive state, plasma glucose and insulin levels, glucose utilization, and EGP were similar in hyperandrogenic patients and healthy women. During variable hyperglycemic-hyperinsulinemic infusions, glucose use increased and EGP decreased to similar degrees in both groups of women. Three-month GnRH-a administration to hyperandrogenic patients and healthy women did not affect plasma glucose and insulin levels, glucose utilization and EGP in the postabsorptive state, or glucose utilization and EGP during variable hyperglycemic-hyperinsulinemic infusions. CONCLUSION(S): Glucose use and EGP in the postabsorptive state and during variable hyperglycemic-hyperinsulinemic infusions are similar in hyperandrogenic anovulatory patients and healthy women of similar body fat distribution and are unaffected by 3-month GnRH-a administration.

Pituitary desensitization to gonadotropin-releasing hormone increases abdominal adiposity in hyperandrogenic anovulatory women.

OBJECTIVE: To determine whether hyperandrogenism in anovulatory women affects body fat distribution. DESIGN: Prospective nonrandomized study. SETTING: An academic research environment. PATIENT(S): Ten hyperandrogenic anovulatory patients and 10 healthy women matched by body mass index. INTERVENTION(S): Regional body fat analysis was performed before and after 3 months of GnRH analogue (GnRH-a) therapy. MAIN OUTCOME MEASURE(S): Body fat distribution was measured by waist-to-hip circumference ratio, single-slice computed tomography imaging (L2-3 interspace), and total body dual-energy x-ray absorptiometry. RESULT(S): Weight, body mass index, waist-to-hip circumference ratio, total body and leg fat mass, and subcutaneous adipose area were unaffected by the presence of hyperandrogenism or the use of GnRH-a therapy. Basal abdominal fat mass, abdomen-to-leg fat mass ratio, visceral adipose area, and total visceral adipose volume were comparable in both study groups. The abdominal fat mass increased in both groups during GnRH-a therapy, whereas the abdomen-to-leg fat mass ratio rose significantly only in the hyperandrogenic patients. During GnRH-a therapy, the hyperandrogenic patients demonstrated a significant increase in visceral adipose area compared with the healthy women so that total visceral adipose volume increased significantly in the former but not the latter. CONCLUSION(S): Three months of GnRH-a administration preferentially increased abdominal fat, as measured by single-slice computed tomography imaging and total body dual-energy x-ray absorptiometry, in hyperandrogenic anovulatory women.

The good ol' days is now: trends in operative experience of general surgical residents over 25 years.

To define the changing trends in operative experience of general surgery residents, the records of all residents completing our training program from 1964-1987 were reviewed. Except for a slight decline in operative experience in head and neck and gastric surgery, the experience in other primary component procedures either remained stable (major breast, esophagus, intestine, colon, pancreas, spleen and endocrine) or increased (minor breast, anorectal, hernia, biliary, vascular and trauma). A rich experience in secondary component procedures was maintained in thoracic, pediatric and plastic surgery, all of which are services within the department of surgery. A relatively low but stable experience in gynecology, neurosurgery, orthopaedics and urology has been reported, which did not change when these disciplines became separate departments. Finally, there has been a dramatic increase in endoscopic procedures performed in the surgery department despite the presence of endoscopic services in other departments. It is believed that such an institutional review of surgical resident caseload over time will be of help not only to program directors but also to accrediting and certifying organizations concerned with surgical training programs and their graduates.

The relationship between command hallucinations and violence.

OBJECTIVE: The purpose of this study was to describe the relationship between command hallucinations and violent behavior. METHODS: One hundred and three psychiatric inpatients completed measures of command hallucinations, other psychotic symptoms, violent behavior, and social desirability response biases. RESULTS: Thirty percent of the patients reported having had command hallucinations to harm others during the last year, and 22 percent of the patients reported they complied with such commands. Logistic regression analyses suggested that patients who experienced command hallucinations to harm others were more than twice as likely to be violent, even when the analysis controlled for demographic variables, history of substance abuse, and social desirability response biases. CONCLUSIONS: The results support the clinical utility of asking about command hallucinations when assessing the risk of violence in patients with major mental disorders.

Instructional and information technology initiatives: the potential for delivery.

An attempt has been made to discuss some of the issues and opportunities which lie ahead as dental educators, their institutions, and our national associations prepare for the expected growth in the instructional and informational technologies that curriculum reform and technological advances will promote. The issues stem from a perceived need to collectively deliver products, as well as discuss issues, within our associations. While most national professional associations are well equipped to focus on questions of policy rather than the production of specific products, I believe there is a real potential for the successful pursuit of both within dental education.

Dental students' perceptions of the difficulty of faculty positions.

How undergraduate dental students at Dalhousie University perceive various aspects of the positions held by faculty members was determined by responses on a 20-item questionnaire. Comparisons of item responses by students' class year, age group, marital status, sex, and perceived class standing generally produced a similar rank order of questionnaire items. Students perceived faculty positions that involved a high degree of administrative responsibility as being more difficult than preclinical instruction and part-time faculty positions. Research was perceived by students to be of low importance to faculty. It is important to consider the various perceptions that students hold regarding faculty positions if changes are planned to improve the teaching environment. A wide divergence between the perception held by faculty and students regarding the difficulties of a faculty position may hinder optimum student-faculty relationships.

Changes and challenges in Canadian dental faculties.

Canadian dental faculty were surveyed to determine changing career interests, sources of satisfaction, and professional development needs. The respondents indicated a desire to change the proportion of time allocated to their major responsibilities in ways that could create serious problems for dental faculties, i.e. more time on research, with less time on teaching and administration. While most reported teaching as a source of satisfaction and happiness, relatively few reported it as recognized and rewarded. The different status accorded to teachers, clinicians, and researchers, as reflected in the division of workload and rewards have created dissatisfaction among faculty, perhaps contributing to the fact that over 50 percent of respondents reported considering leaving academia. Faculties of Dentistry must determine what is required to reestablish a productive and enjoyable balance among their roles as teacher, researcher, and clinician and to determine what type of environment will best support the development of today's dental academics and tomorrow's dentists.

The student survey of problems in the academic environment in Canadian dental faculties.

A survey of problems related to stress encountered by 1,255 Canadian dental students was conducted. Substantial experience with problems was reported infrequently, although most students were affected negatively by at least one problem. Most difficulties concerned students' doubts about harnessing their efforts and abilities to master large amounts of material, which, of necessity, reduced their opportunity to pursue other interests. Few demographic features predicted the level of students' problems, although there was an indication that those who perceived themselves above average academically reported fewer problems.

The computer-based oral health record: an essential tool for cross-provider quality management.

A more efficient and detailed exchange of information between the various professionals who provide healthcare for an individual patient could have a strong positive impact on both quality assurance and patient health. This paper examines many of the issues relevant to cross-provider communication and quality assurance mechanisms in the computer-based oral health record.