Wnt signalling in murine postnatal mammary gland development

The mammary gland undergoes numerous developmental processes postnatally, from the elongation of the ductal tree-like structure to pregnancy-induced lobulo-alveolar development. Mammary epithelial stem cells have been suggested to be central to the control of enormous tissue expansion and remodelling during phases of mammary development. The Wnt signalling pathway plays a critical role in these biological steps and is suggested to be involved in the maintenance of the stem cell population. This review provides insight into recent findings on the activity of Wnt signalling during ductal and lobular mammary development and discusses the potential interplay between Wnt signals and mammary stem cells in mice.

Cyclopropenylidene carbene ligands in palladium catalysed coupling reactions: carbene ligand rotation and application to the Stille reaction

Reaction of [Pd(PPh(3))(4)] with 1,1-dichloro-2,3-diarylcyclopropenes gives complexes of the type cis-[PdCl(2)(PPh(3))(C(3)(Ar)(2))] (Ar = Ph 5, Mes 6). Reaction of [Pd(dba)(2)] with 1,1-dichloro-2,3-diarylcyclopropenes in benzene gave the corresponding binuclear palladium complexes trans-[PdCl(2)(C(3)(Ar)(2))](2) (Ar = Ph 7, p-(OMe)C(6)H(4)8, p-(F)C(6)H(4)9). Alternatively, when the reactions were performed in acetonitrile, the complexes trans-[PdCl(2)(NCMe)(C(3)(Ar)(2))] (Ar = Ph 10, p-(OMe)C(6)H(4)11 and p-(F)C(6)H(4)) 12) were isolated. Addition of phosphine ligands to the binuclear palladium complex 7 or acetonitrile adducts 11 and 12 gave complexes of the type cis-[PdCl(2)(PR(3))(C(3)(Ar)(2))] (Ar = Ph, R = Cy 13, Ar = p-(OMe)C(6)H(4), R = Ph 14, Ar = p-(F)C(6)H(4), R = Ph 15). Crystal structures of complexes 6·3.25CHCl(3), 10, 11·H(2)O and 12-15 are reported. DFT calculations of complexes 10-12 indicate the barrier to rotation about the carbene-palladium bond is very low, suggesting limited double bond character in these species. Complexes 5-9 were tested for catalytic activity in C-C coupling (Mizoroki-Heck, Suzuki-Miyaura and, for the first time, Stille reactions) and C-N coupling (Buchwald-Hartwig amination) showing excellent conversion with moderate to high selectivity.

The effects of aviation-style non-technical skills training on technical performance and outcome in the operating theatre

Unintended harm to patients in operating theatres is common. Correlations have been demonstrated between teamwork skills and error rates in theatres. This was a single-institution uncontrolled before-after study of the effects of "non-technical" skills training on attitudes, teamwork, technical performance and clinical outcome in laparoscopic cholecystectomy (LC) and carotid endarterectomy (CEA) operations. The setting was the theatre suite of a UK teaching hospital. Attitudes were measured using the Safety Attitudes Questionnaire (SAQ). Teamwork was scored using the Oxford Non-Technical Skills (NOTECHS) method. Operative technical errors (OTEs), non-operative procedural errors (NOPEs), complications, operating time and length of hospital stay (LOS) were recorded. A 9 h classroom non-technical skills course based on aviation "Crew Resource Management" (CRM) was offered to all staff, followed by 3 months of twice-weekly coaching from CRM experts. Forty-eight procedures (26 LC and 22 CEA) were studied before intervention, and 55 (32 and 23) afterwards. Non-technical skills and attitudes improved after training (NOTECHS increase 37.0 to 38.7, t = -2.35, p = 0.021, SAQ teamwork climate increase 64.1 to 69.2, t = -2.95, p = 0.007). OTEs declined from 1.73 to 0.98 (u = 1071, p = 0.009), and NOPEs from 8.48 to 5.16 per operation (t = 4.383, p<0.001). These effects were stronger in the LC group than in CEA procedures. The operating time was unchanged, and a non-significant reduction in LOS was observed. Non-technical skills training improved technical performance in theatre, but the effects varied between teams. Considerable cultural resistance to adoption was encountered, particularly among medical staff. Debriefing and challenging authority seemed more difficult to introduce than other parts of the training. Further studies are needed to define the optimal training package, explain variable responses and confirm clinical benefit.

Should we continue screening rhesus D positive women for the development of atypical antibodies in late pregnancy?

OBJECTIVE

The purpose of this study was to calculate the incidence of the new development of atypical antibodies (other than anti-rhesus D) in women attending for antenatal care, and to assess the clinical impact and cost-effectiveness of a second test to detect these antibodies.

METHOD

A three-year retrospective analysis was undertaken to calculate the number of rhesus positive women who developed new antibodies in the last trimester of pregnancy.

RESULTS

Of 13,143 rhesus positive women, 20 (0.15%) developed new antibodies; fetal outcome was not compromised in any of these cases.

CONCLUSION

Repeat testing in late pregnancy would appear an unnecessary expense in our population.

The influence of non-technical performance on technical outcome in laparoscopic cholecystectomy

INTRODUCTION

Evidence from other professions suggests that training in teamwork and general cognitive abilities, collectively described as non-technical skills, may reduce accidents and errors. The relationship between non-technical teamwork skills and technical errors was studied using a behavioural marker system validated in aviation and adapted for use in surgery.

METHOD

26 elective laparoscopic cholecystectomies were observed. Simultaneous assessments were made of surgical technical errors, by observation clinical human reliability assessment (OCHRA) task analysis, and non-technical performance, using the surgical NOTECHS behavioural marker system. NOTECHS assesses four categories: (1) leadership and management, (2) teamwork cooperation, (3) problem-solving and decision-making, (4) situation awareness. Each subteam (nurses, surgeons and anaesthetists) was scored separately on each of the four dimensions. Two observers - one surgical trainee and one human factors expert - were used to assess intra-rater reliability.

RESULTS

The mean NOTECHS team score was 35.5 (95% C.I. +/- 1.88). The mean subteam scores for surgeons, anaesthetists and nurses were 13.3 (95% C.I. +/- 0.64), 11.4 (95% C.I. +/- 1.05), and 10.8 (95% C.I. +/- 0.87), respectively, with a significant difference between surgeons and anaesthetists (U = 197, p = 0.009), and surgeons and nurses (U = 0.134, p <or= 0.001). Inter-rater reliability was found to be strong (alpha = 0.88). There were between zero and six technical errors per operation, with a mean of 2.62 (95% C.I. +/- 0.55), which were negatively correlated with the surgeons situational awareness scores (rho = -0.718, p < 0.001).

CONCLUSIONS

Non-technical skills are an important component of surgical skill, particularly in relation to the development and maintenance of a surgeon's situational awareness. Experience from other industries suggests that it may be possible to improve the ability of surgeons to manage their own situation awareness, through training, intraoperative briefings and intraoperative workload management. In the future, it may be possible to use non-technical performance as a surrogate measure for technical performance, either for early identification of surgical difficulties, or as a method of evaluation by which non-surgically trained observers.

Identification of systems failures in successful paediatric cardiac surgery

Patient safety will benefit from an approach to human error that examines systemic causes, rather than blames individuals. This study describes a direct observation methodology, based on a threat and error model, prospectively to identify types and sources of systems failures in paediatric cardiac surgery. Of substantive interest were the range, frequency and types of failures that could be identified and whether minor failures could accumulate to form more serious events, as has been the case in other industries. Check lists, notes and video recordings were employed to observe 24 successful operations. A total of 366 failures were recorded. Coordination and communication problems, equipment problems, a relaxed safety culture, patient-related problems and perfusion-related problems were most frequent, with a smaller number of skill, knowledge and decision-making failures. Longer and more risky operations were likely to generate a greater number of minor failures than shorter and lower risk operations, and in seven higher-risk cases frequently occurring minor failures accumulated to threaten the safety of the patient. Non-technical errors were more prevalent than technical errors and task threats were the most prevalent systemic source of error. Adverse events in surgery are likely to be associated with a number of recurring and prospectively identifiable errors. These may be co-incident and cumulative human errors predisposed by threats embedded in the system, rather than due to individual incompetence or negligence. Prospectively identifying and reducing these recurrent failures would lead to improved surgical standards and enhanced patient safety.

Modifying the specificity of an RNA backbone contact

The interaction between the MS2 bacteriophage coat protein homodimer and its cognate RNA hairpin is facilitated by 21 different RNA-protein contacts. In one of these contacts, the 2'-hydroxyl group at ribose -5 of the RNA acts as a hydrogen bond donor to Glu63 in one subunit of the protein. Previous experiments showed that substitution of ribose -5 with deoxyribose resulted in a 24-fold decrease in binding affinity between RNA and protein. Using a protein where the two MS2 monomers were fused to increase stability, the contribution of this contact to the overall binding affinity was investigated by site-directed mutagenesis. When Glu63 was substituted with glutamine, aspartate, or alanine, the binding affinity of the hairpin for the protein was weakened by 12 to 100-fold, similar to that observed with deoxyribose at position -5. However, the specificity of the three mutant proteins for RNAs with various modifications at the 2'-position of ribose -5 differed dramatically. While the Glu63Asp protein resembled the wild-type protein in preferring the 2'-hydroxyl group over a proton or a bulky 2'-substituent, both the Glu63Ala and Glu63Gln proteins preferred bulky 2'-substituents over the 2'-hydroxyl group by more than 100-fold. These experiments emphasize the ease with which the specificity of a protein-nucleic acid interaction can be changed at thermodynamically important sites.

Accurate case finding using linked electronic clinical and administrative data at a children's hospital

To link hospital administrative data and an electronic medical record at a children's hospital in order to identify children with cancer admitted for fever and neutropenia. Hospital administrative data concerning 13,374 inpatient and outpatient encounters were validated against and linked to clinical data stored in an electronic medical record. Queries of the linked databases identified children with fever and neutropenia. Sensitivity and specificity of the experimental case-finding strategy were determined and compared to a control case-finding strategy utilizing administrative data alone. Linking of the clinical record to the administrative record was achieved in 233 (99%) of the 235 records. Of 1680 data elements reviewed from the administrative data that were also potentially available in the clinical data system, 1679 (99.9%) were verified in the electronic medical record. The experimental strategy for case finding had a sensitivity of 73.1% (95% CI: 58.1, 88.3), specificity 99.6% (95% CI: 99.1, 100). If only administrative data such as diagnosis-related group and hospital service were used for case finding, both the sensitivity (P < 0.01) and specificity (P < 0.01) were significantly lower. Linking a children's hospital administrative data system with clinical data is feasible and can be utilized for specific case finding for a common and costly condition in children.

Wnt/Shh interactions regulate ectodermal boundary formation during mammalian tooth development

Interactions between the Wnt (wingless) and hedgehog signaling pathways were first described as playing a role in establishing boundaries between ectodermal cells in Drosophila segmentation. During the initiation of mammalian tooth development, boundaries that distinguish oral from dental ectoderm must be formed to correctly position the sites of tooth formation. We describe a reciprocal relationship between the expression of Wnt-7b in presumptive oral ectoderm and Shh in presumptive dental ectoderm in mouse embryos that mark boundaries between these cells with different developmental fates. By using a murine retrovirus to ectopically express Wnt-7b in presumptive dental ectoderm in mandibular arch explants, we show that Shh expression in the ectoderm and Ptc expression in the underlying ectomesenchyme are down-regulated, and tooth development is subsequently arrested. This suggests that Wnt-7b acts to repress Shh expression in oral ectoderm, thus maintaining the boundaries between oral and dental ectodermal cells. Implantation of beads soaked in Shh protein into Wnt-7b-infected explants resulted in complete rescue of tooth development, confirming that the repressive action of Wnt-7b specifically affects Shh signaling.

A test of the model to predict unusually stable RNA hairpin loop stability

To investigate the accuracy of a model [Giese et al., 1998, Biochemistry37:1094-1100 and Mathews et al., 1999, JMol Biol 288:911-940] that predicts the stability of RNA hairpin loops, optical melting studies were conducted on sets of hairpins previously determined to have unusually stable thermodynamic parameters. Included were the tetraloops GNRA and UNCG (where N is any nucleotide and R is a purine), hexaloops with UU first mismatches, and the hairpin loop of the iron responsive element, CAGUGC. The experimental values for the GNRA loops are in excellent agreement (deltaG degrees 37 within 0.2 kcal/mol and melting temperature (TM) within 4 degrees C) with the values predicted by the model. When the UNCG hairpin loops are treated as tetraloops, and a bonus of 0.8 kcal/mol included in the prediction to account for the extra stable first mismatch (UG), the measured and predicted values are also in good agreement (deltaG degrees 37 within 0.7 kcal/mol and TM within 3 degrees C). Six hairpins with unusually stable UU first mismatches also gave good agreement with the predictions (deltaG degrees 37 within 0.5 kcal/mol and TM within 8 degrees C), except for hairpins closed by wobble base pairs. For these hairpins, exclusion of the additional stabilization term for UU first mismatches improved the prediction (AG degrees 37 within 0.1 kcal/mol and TM within 3 degrees C). Hairpins with the iron-responsive element loop were not predicted well by the model, as measured deltaG degrees 37 values were at least 1 kcal/mol greater than predicted.

Stability of RNA hairpins closed by wobble base pairs

Thermodynamic parameters are reported for hairpin formation in 1 M NaCl by RNA sequences of the type GGXANmAYCC, where XY is the wobble base pair, GU or UG, and the underlined loop sequences are three to eight nucleotides. A nearest-neighbor analysis indicates the free energy of loop formation is dependent upon loop size and closing base pair. Hairpin loops closed by UG base pairs are on average 1.3 kcal/mol less stable than hairpins closed by GU base pairs. The hairpin loops closed by UG have approximately the same stability as hairpin loops closed by AU/UA base pairs, while the loops closed by GU are approximately 0.7 kcal/mol more stable than hairpins loops closed by GC/CG base pairs. These results, combined with the model previously developed [Serra et al. (1997) Biochemistry 36, 4844] to predict the stability for hairpin loops closed by Watson-Crick base pairs, allow for the following model to predict the stability of hairpin loops: delta G degree 37L(n) = delta G degree 37iL(n) + delta G degree 37mm + 0.6 (if closed by AU, UA, or UB) - 0.7 (if closed by GU) - 0.7 (if first mismatch is GA or UU except for loops closed by GU). Here, delta G degree 37iL(n) is the free energy increment for initiating a loop of n nucleotides with a CG or GC pair, and delta G degree 37mm is the free energy for the interaction of the first mismatch with the closing base pair. For hairpin loops of n = 4-9, delta G037iL(n) is 4.9, 5.0, 5.0, 5.0, 4.9, and 5.5 kcal/mol, respectively. For hairpin loops of n = 3, delta G degree 37L(3) = +4.8 + 0.6 (if closed by AU, UA, or UG) kcal/mol. Thermodynamic parameters for hairpin formation in 1 M NaCl for 13 naturally occurring RNA hairpin sequences closed by wobble base pairs are reported. The model provides good agreement for both TM and delta G degree 37 for most hairpins studied. Thermodynamic values for five terminal mismatches adjacent to wobble base pairs are also reported.

HGF/SF: a potent cytokine for mammary growth, morphogenesis and development

The mammary gland is a renewing tissue in which morphogenetic processes and differentiation occur cyclically during the menstrual cycle, pregnancy and lactation. These events have been shown to be dependent upon epithelial-mesenchymal interactions. Studies of the effects of individual factors, their cellular source and their target cell populations in the different developmental stages of the mammary gland are greatly facilitated by the accessibility of this organ and the application of new techniques that allow purification of the major epithelial and stromal components of this tissue. Here we demonstrate that HGF/SF and its cellular receptor, c-met, are expressed and regulated temporally during mouse mammary development and differentiation. We show that human and mouse mammary fibroblasts produce HGF/SF and that HGF/SF is not only mitogenic but morphogenic and motogenic for both human and mouse mammary epithelial cells. We have found that human luminal and myoepithelial cells express c-met differentially and that HGF/SF has different effects on these two mammary epithelial cell populations. HGF/SF is mitogenic for luminal cells but not myoepithelial cells, and morphogenic to myoepithelial cells but not luminal cells. This is discussed in the context of the proliferative compartments in the normal mammary gland and the potential role of the myoepithelial cells to act as the skeleton for ductal development.

Sexual behavior, communication, and chlamydial infections among college women

The sexual practices, partner communication patterns, and prevalence of chlamydial infection were determined in a sample of college women. Specific inclusion criteria were used to screen 146 participants. The presence of a mucopurulent cervical discharge was the only criterion significantly associated with infection. Only 12% of the sample used condoms alone or in combination with another birth control method, and only 31% of the women discussed with their partner their own or their partner's sexual history. Thirty-eight percent of the sample reported a history of one to four episodes of a sexually transmitted disease, and 21% of the women stated they had had two or more sexual partners within the past 6 months. Health providers, counselors, and women themselves must address this health issue with more assertive behavior and communication skills.

Anti-emetic profile of a non-peptide neurokinin NK1 receptor antagonist, CP-99,994, in ferrets

In the ferret, 5-HT3 receptor antagonists are effective in controlling emesis produced by cytotoxic agents or radiation. To investigate the possibility that substance P has a role, as well as 5-HT, in the emetic reflex pathway, we have examined the anti-emetic effects of a NK1 receptor antagonist (racemic CP-99,994) in the ferret. Racemic CP-99,994 was effective against a range of emetogens, comprising cytotoxic drugs, radiation, morphine, ipecacuanha and copper sulphate.

[Anesthetic gases, the ozone layer and the greenhouse effect. How harmful are the anesthetic emissions for the global environment?]

During the last decade, world society has acknowledged the harmful effects on the environment of the greenhouse effect and of depletion of the ozone layer, caused by industrial emissions of man-made compounds. Ozone depletion is caused mainly by chlorine compounds or nitrogen oxides released by degradation in the stratosphere. The greenhouse effect is caused by increased trapping of terrestrial heat radiation. Degradation of the anaesthetic vapours halothane, enflurane and isoflurane releases chlorine, and nitrous oxide degradation produces reactive nitrogen oxides. Nitrous oxide in particular, but also the vapours, absorb terrestrial radiation. The total discharge of anaesthetic vapours contributes to less than 0.01% of the total atmospheric chlorine load, and the annual Norwegian release of approximately two tons accounts for 0.2% of the world total. It is estimated that the total amount of nitrous oxide released from anaesthetics accounts for 0.05% of the greenhouse effect, while annual Norwegian emissions of nitrous oxide (less than 160 tons) comprise 0.2-0.4% of world total. Because of their favourable clinical properties and their modest contribution to ozone depletion and the greenhouse effect, medical use of inhalational anaesthetic agents should not be banned. However, low flow anaesthetic techniques should be employed, in order to reduce their negative impacts on the atmosphere.