A study of self-care among Irish doctors

Little is known about the self care employed by Irish doctors, though studies in other countries suggest this is likely to be less than ideal. In this study 76 doctors; general practitioner trainees, general practitioners and hospital consultants, completed a questionnaire on their self management of illness. High levels of self-prescribing and referral were discovered. The implications for the health of doctors in Ireland and the need for an occupational health service for doctors are discussed.

The dependence of chemical exchange on boundary selection in a fibronectin type III domain from human tenascin

The third fibronectin type III domain from human tenascin adopts a compact beta-sandwich fold. Its boundaries were originally selected to encode a 90-residue domain (TNfn31-90). We conclude that the dynamic properties of TNfn3 are more accurately represented when the C terminus is extended by the two naturally succeeding residues. Longitudinal (R1) and transverse (R2) 15N relaxation rates, and ¿1H-15N¿ NOE enhancements at pH 4.9 and 300 K are presented for TNfn31-90 and TNfn31-92, the extended form, at two field strengths (11.74 and 14.10 T). Nearly identical results confirm their similar motional properties over a broad range of timescales. However, a number of residues near the C terminus in TNfn31-90 exhibit elevated transverse relaxation rates and broadened signals in 1H-15N HSQC spectra. Explicit rates of chemical exchange for five residues in TNfn31-90 were determined by measuring transverse relaxation rates in a series of CPMG experiments with spin-echo refocusing delays increasing from 311 to 1436 micros. Calculated exchange rates average 1000(+/-311) s-1, with individual uncertainties near 20%. Homonuclear TOCSY experiments collected between pH 4 and 7 reveal the coincident titration of two acidic clusters in TNfn31-90 at pH 5. 64(+/-0.47). The repulsive electrostatic interaction of the C-terminal carboxylate with one of these clusters may promote chemical exchange in the shorter domain. Additionally, NOE and chemical shift data suggest hydrogen bond formation between the added residues and adjacent loops. The data affirm the importance of judiciously selecting domain boundaries prior to the characterization of molecular properties.

HIV/AIDS patients' perspectives on adhering to regimens containing protease inhibitors

OBJECTIVE

To gather qualitative data regarding HIV/AIDS patients' perspectives about HIV-1 protease inhibitors (PIs), and about their experiences taking and adhering to regimens containing PIs.

DESIGN

Six focus groups of persons under care for HIV were conducted between September and November 1996 regarding participants' knowledge, awareness, experiences when taking, and adherence to antiretroviral regimens containing PIs. An identical discussion guide was used to facilitate all six groups. Focus group proceedings were audiotaped, transcribed, coded for themes, and analyzed qualitatively.

SETTING

HIV/AIDS practices of three teaching hospitals and two community health centers.

PATIENTS/PARTICIPANTS

Fifty-six patients with HIV disease: 28 men and 28 women.

MEASUREMENTS AND MAIN RESULTS

Knowledge and positive impressions of PIs were prevalent among this diverse group of persons with HIV, and did not differ by race/ethnicity or gender. Most knew that these were new, potent medications for treating HIV/AIDS. Networks of persons with HIV and medical providers were the most important information sources. Those taking PIs were aware that adherence to the regimen is important, and most were using special strategies to maximize their own adherence, but expressed considerable frustration about the central role these medication regimens had assumed in their life. A subset who did not believe they would adhere to these regimens had declined treatment with them. Motivating factors for taking and adhering to these complex regimens were improving CD4 counts and viral loads and the patient-provider relationship.

CONCLUSIONS

Among those with HIV/AIDS, awareness of PIs and their effectiveness is substantial, owing to the impact of informal networks and medical providers. This early positive "reputation" of PIs may enhance motivation for adherence. Those who are taking PIs invest substantial effort adhering to these complex regimens, but resent the need to make medications the focus of their lives.

Binding of insulin-like growth factor (IGF)-binding protein-5 to smooth-muscle cell extracellular matrix is a major determinant of the cellular response to IGF-I

Insulin-like growth factor-binding protein-5 (IGFBP-5) has been shown to bind to fibroblast extracellular matrix (ECM). Extracellular matrix binding of IGFBP-5 leads to a decrease in its affinity for insulin-like growth factor-I (IGF-I), which allows IGF-I to better equilibrate with IGF receptors. When the amount of IGFBP-5 that is bound to ECM is increased by exogenous addition, IGF-I's effect on fibroblast growth is enhanced. In this study we identified the specific basic residues in IGFBP-5 that mediate its binding to porcine smooth-muscle cell (pSMC) ECM. An IGFBP-5 mutant containing alterations of basic residues at positions 211, 214, 217, and 218 had the greatest reduction in ECM binding, although three other mutants, R214A, R207A/K211N, and K202A/R206N/R207A, also had major decreases. In contrast, three other mutants, R201A/K202N/R206N/R208A, and K217N/R218A and K211N, had only minimal reductions in ECM binding. This suggested that residues R207 and R214 were the most important for binding, whereas alterations in K211 and R218, which align near them, had minimal effects. To determine the effect of a reduction in ECM binding on the cellular replication response to IGF-I, pSMCs were transfected with the mutant cDNAs that encoded the forms of IGFBPs with the greatest changes in ECM binding. The ECM content of IGFBP-5 from cultures expressing the K211N, R214A, R217A/R218A, and K202A/R206N/R207A mutants was reduced by 79.6 and 71.7%, respectively, compared with cells expressing the wild-type protein. In contrast, abundance of the R201A/K202N/R206N/R208A mutant was reduced by only 14%. Cells expressing the two mutants with reduced ECM binding had decreased DNA synthesis responses to IGF-I, but the cells expressing the R201A/K202N/R206N/R208A mutant responded well to IGF-I. The findings suggest that specific basic amino acids at positions 207 and 214 mediate the binding of IGFBP-5 to pSMC/ECM. Smooth-muscle cells that constitutively express the mutants that bind weakly to ECM are less responsive to IGF-I, suggesting that ECM binding of IGFBP-5 is an important variable that determines cellular responsiveness.

The effect of boundary selection on the stability and folding of the third fibronectin type III domain from human tenascin

Correct selection of domain boundaries is critical for structural analysis of single domains from multimodular proteins. Folding and stability studies of the third fibronectin type III domain from human tenascin (TNfn31-90) have shown that it is moderately stable (Delta G(D-N)(H2O) approximately 5 kcal mol-1) and folds with two-state kinetics. In an attempt to stabilize the protein, five domains were constructed with different combinations of extensions to the N- and C-termini. Thermal denaturation studies show that a specific two amino acid (Gly-Leu) extension at the C-terminus is primarily responsible for a significant increase in stability. The Delta Delta G(D-N)(H2O) of the Gly-Leu extension (TNfn3(1-92)) is 2.7 +/- 0.3 kcal mol-1. Refolding kinetics do not differ significantly, but unfolding is slowed 40-fold. Mutation of leucine 92 to alanine does not affect stability, indicating that the stability of the extension does not come from the packing of the leucine side chain. Hydrogen exchange data suggest that the extension adds new hydrogen bonds and strengthens existing hydrogen bonds in the C-terminal interaction with the A-B and E-F loops. Removal of a very small number of hydrogen bonds substantially increases the unfolding rate, a phenomenon which may be important in stress-relaxation of FNIII-containing muscle proteins such as titin. These experiments demonstrate the importance of a small number of additional long-range interactions in the overall formation of a compact independently folding beta-sheet module.

Physical assault in New Zealand: the experience of 21 year old men and women in a community sample

AIM

To obtain epidemiological information on physical assault in a high risk group of New Zealanders.

METHOD

Rates of physical assault in the preceding twelve months were ascertained by interview in a cohort of 21 year old, Dunedin-born men (n = 482) and women (n = 462).

RESULTS

Forty-five percent of the men and one quarter of the women reported at least one physical assault, either completed, attempted or threatened. A small proportion of these received medical treatment. Most serious assaults were by a perpetrator who was thought to have been drinking alcohol. Most assaults on men were by strangers but partners carried out more assaults against women, especially those receiving medical treatment. One quarter of all assaults on women were by other women, compared to 15% of the assaults on men. Differences between patterns of assaults on women and on men are discussed.

CONCLUSION

It is important for doctors to be aware of the widespread occurrence of interpersonal violence in New Zealand and its underreporting.

Characterisation of urea-denatured states of an immunoglobulin superfamily domain by heteronuclear NMR

The structural and dynamic properties of an immunoglobulin superfamily domain (IgSF), Ig 18', have been characterised by NMR at 285 K, in the presence of 4.2 M and 6.0 M urea, respectively. Analysis of chemical shift deviations, 3JHNHalpha coupling constants, sequential NOE pattern, and 15N relaxation data reveals that although the two urea-denatured states are highly disordered, some local turn-like residual structures do exist. Moreover, some distinct differences between the properties of the two denatured states are observed. In 4.2 M urea-denatured Ig 18', regions 80-83 and 86-92 adopt turn-like conformations, furthermore, region 84-93 is involved in slow exchange processes that occur on a micro- to millisecond time-scale. In the 6.0 M urea-denatured state, these turn-like conformations are less occupied, and chemical exchange processes in region 84-93 are largely reduced. In contrast, region 32-36 has persistent turn-like structures in both urea-denatured states. Some correlation between the spectral density function at 0 frequency, Jeff(0), for the urea-denatured states and the secondary structure elements of the folded state have been observed. Except for the terminal regions, residues corresponding to beta-strands have higher Jeff(0) values compared to residues corresponding to loops. The characterisation and comparison of the two urea-denatured states highlight residues that possess properties that may be crucial for the initiation of folding of this domain.

SQUID detected NMR and NQR. Superconducting Quantum Interference Device

The dc Superconducting QUantum Interference Device (SQUID) is a sensitive detector of magnetic flux, with a typical flux noise of the order 1 muphi0 Hz(-1/2) at liquid helium temperatures. Here phi0 = h/2e is the flux quantum. In our NMR or NQR spectrometer, a niobium wire coil wrapped around the sample is coupled to a thin film superconducting coil deposited on the SQUID to form a flux transformer. With this untuned input circuit the SQUID measures the flux, rather than the rate of change of flux, and thus retains its high sensitivity down to arbitrarily low frequencies. This feature is exploited in a cw spectrometer that monitors the change in the static magnetization of a sample induced by radio frequency irradiation. Examples of this technique are the detection of NQR in 27Al in sapphire and 11B in boron nitride, and a level crossing technique to enhance the signal of 14N in peptides. Research is now focused on a SQUID-based spectrometer for pulsed NQR and NMR, which has a bandwidth of 0-5 MHz. This spectrometer is used with spin-echo techniques to measure the NQR longitudinal and transverse relaxation times of 14N in NH4ClO4, 63+/-6 ms and 22+/-2 ms, respectively. With the aid of two-frequency pulses to excite the 359 kHz and 714 kHz resonances in ruby simultaneously, it is possible to obtain a two-dimensional NQR spectrum. As a third example, the pulsed spectrometer is used to study NMR spectrum of 129Xe after polariza-tion with optically pumped Rb. The NMR line can be detected at frequencies as low as 200 Hz. At fields below about 2 mT the longitudinal relaxation time saturates at about 2000 s. Two recent experiments in other laboratories have extended these pulsed NMR techniques to higher temperatures and smaller samples. In the first, images were obtained of mineral oil floating on water at room temperature. In the second, a SQUID configured as a thin film gradiometer was used to detect NMR in a 50 microm particle of 195Pt at 6 mT and 4.2 K.

Screening for cognitive impairment in general practice: toward a consensus

We considered whether general practitioners should examine all older patients over a certain age for cognitive impairment in screening for early dementia. We invited presentations from key experts, selectively reviewed the literature, and developed a consensus statement. The efficacy of and benefits from unselective use of cognitive testing and informant questionnaires for detecting early dementia in older patients attending general practice are limited. Positive predictive values of cognitive screening for dementia are less than 50%, even for older patient populations. Higher values may be obtained by testing patients who have a relevant history of cognitive or functional decline. Whatever procedures are adopted for screening older general practice attenders for cognitive impairment or early dementia, investigation is still required into the relative merits of different health professionals performing the screening, the positive and negative effects on patients and their families, and the cost-benefit ratio. The majority view of workshop participants was that cognitive testing should occur for older patients when there is a reason to suspect dementia. Testing may occur in an individual considered to be at risk because of an informant history of cognitive or functional decline, clinical observation, or, sometimes, very old age. No single instrument for cognitive screening is suitable for global use. Screening programs must be supported by training and supplemented by education for professionals and families in management of dementia.

Folding intermediates of wild-type and mutants of barnase. II. Correlation of changes in equilibrium amide exchange kinetics with the population of the folding intermediate

There is an unanswered question from previous studies of 1H/2H-exchange of amide protons of barnase. Under certain conditions, there is a relatively abrupt change from EX2 towards EX1 kinetics as the temperature is slightly increased. The change in kinetics for different mutants is not directly related to their changes in stability. We have measured the stability of the folding intermediate of barnase (I) in 2H2O under a variety of conditions and calculated its population at different temperatures. The change in kinetics correlates with the change in the population of the folding intermediate. At higher temperatures and pH, the free energy of I becomes higher than that of the denatured state, D, and the kinetics becomes EX1. The data fit a simple kinetic scheme. Such changes in kinetics may be used to detect the presence of intermediates in the folding reaction at equilibrium in native conditions, but cannot distinguish whether they are on or off-pathway.

Hydrogen exchange and protein folding

Amide hydrogen-deuterium exchange is a sensitive probe of the structure, stability and dynamics of proteins. The significant increase in the number of small, model proteins that have been studied has allowed a better understanding of the structural fluctuations that lead to hydrogen exchange. Recent technical advances enable the methodology to be applied to the study of protein-protein interactions in much larger, more complex systems.

Maintaining safe oxygen levels in semiclosed underwater breathing apparatus

Semiclosed circuit underwater breathing apparatus (UBAs) are far more conserving of limited gas supplies than either steady-flow, open circuit or demand, open circuit systems. Semiclosed systems recirculate most of the diver's breathing gases, while injecting only a small percentage of the total circuit flow with a fresh makeup supply. The fresh, injected gas supply delivers the necessary makeup to compensate for the oxygen that the diver consumes during each pass through the lungs. This gas-conserving feature makes the utility for semiclosed UBAs for long-duration, deep diving applications more practical than either of the open circuit designs. However, although more gas conservative, these systems maintain variable oxygen levels during a dive that can fluctuate widely with changes in the diver's activity level, depth of the dive, makeup gas composition, or variations in the total circuit volume. It is essential that the oxygen levels in the circuit always remain within physiologically safe limits; neither too low to avoid the onset of hypoxia, nor too high to risk oxygen toxicity. This article presents an analytical assessment of the oxygen levels in semiclosed UBAs. This model allows the designers of semiclosed circuits to predict the effects of UBA circuit volumes, makeup gas compositions, injection rates for the makeup gas, diver depths, and initial circuit oxygen levels on the time-dependent levels of oxygen in these circuits. By using this analytical tool, judicious selection of these design variables can result in the most efficient utilization of the fresh gas supply carried by the diver, and ensure the safe operation of these UBA designs.

Characterization of residual structure in the thermally denatured state of barnase by simulation and experiment: description of the folding pathway

Residual structure in the denatured state of a protein may contain clues about the early events in folding. We have simulated by molecular dynamics the denatured state of barnase, which has been studied by NMR spectroscopy. An ensemble of 10(4) structures was generated after 2 ns of unfolding and following for a further 2 ns. The ensemble was heterogeneous, but there was nonrandom, residual structure with persistent interactions. Helical structure in the C-terminal portion of helix alpha1 (residues 13-17) and in helix alpha2 as well as a turn and nonnative hydrophobic clustering between beta3 and beta4 were observed, consistent with NMR data. In addition, there were tertiary contacts between residues in alpha1 and the C-terminal portion of the beta-sheet. The simulated structures allow the rudimentary NMR data to be fleshed out. The consistency between simulation and experiment inspires confidence in the methods. A description of the folding pathway of barnase from the denatured to the native state can be constructed by combining the simulation with experimental data from phi value analysis and NMR.

Well-being at the end of life: Part 1. A research agenda for psychosocial and spiritual aspects of care from the patient's perspective

This article reviews the scientific literature concerning psychosocial and spiritual aspects of palliative care for the patient with cancer. It discusses 4 separate areas: the continuum of care, communication, spiritual and psychological issues, and psychotherapeutic and behavioural management of physical symptoms. Most of the research could be classified as fundamental according to the Cancer Control Framework of the National Cancer Institute of Canada. In some areas, even fundamental research was lacking. There is a need for clearer and more relevant definitions of the desired outcomes of interventions and also for the development of appropriate quantitative and qualitative methods. We must determine which interventions can be initiated earlier in the disease trajectory and can provide benefit at the palliative phase. Given the burden of suffering that palliative care aims to address, relatively little research in this area has been conducted.

High bicarbonate dialysate in haemodialysis patients: effects on acidosis and nutritional status

BACKGROUND

Metabolic acidosis adversely affects both protein and bone metabolism in patients with chronic renal failure, and could also affect morbidity and mortality. This trial aimed to investigate the effects of different dialysate bicarbonate concentrations on control of acid base balance, and nutritional status.

METHODS

Forty-six stable haemodialysis patients were dialysed using LowBic. (30 mmol/l) or HighBic. (40 mmol/l) bicarbonate dialysate in a single blind double crossover trial, of two consecutive six-month periods. Blood gas analysis, anthropometric indices and dialysis dose were measured, in addition to biochemical indices.

RESULTS

Predialysis 'arterial' plasma pH values were significantly higher when using the HighBic. dialysate (LowBic. 7.38 +/- 0.05, HighBic. 7.43 +/- 0.04, P < 0.001), as was predialysis serum total CO2 at all times during the study (P < 0.01). Kt/V, (LowBic. 1.27 +/- 0.19, HighBic. 1.27 +/- 0.25), urea generation rates (UGR) (LowBic. 1.99 +/- 0.77, HighBic. 1.92 +/- 0.77 mmol/min), and normalized protein catabolic rate (NPCR) (LowBic. 1.04 +/- 0.26, HighBic. 0.99 +/- 0.28 g/kg/day) did not differ, and values of parathroid hormone (PTH) were comparable. Triceps skinfold thickness (TSF) showed a significant change (LowBic. 14.8 +/- 6.9-11.8 +/- 5.5, HighBic. 14.9 +/- 6.3-15.8 +/- 6.4 mm, P < 0.05) which was reversed following dialysate change (HighBic. 11.8 +/- 5.5-13.3 +/- 7.2, LowBic. 15.8 +/- 6.4-13.8 +/- 6.7 mm, P < 0.05). No differences in mid upper arm circumference were found.

CONCLUSIONS

Bicarbonate dialysate concentrations of 40 mmol/l were safe, well tolerated, and produced better control of acidosis, with an increase in TSF, compared to a bicarbonate concentration of 30 mmol/l.

Relationship between dose, distance and time in Sonic Hedgehog-mediated regulation of anteroposterior polarity in the chick limb

Anteroposterior polarity in the vertebrate limb is thought to be regulated in response to signals derived from a specialized region of distal posterior mesenchyme, the zone of polarizing activity. Sonic Hedgehog (Shh) is expressed in the zone of polarizing activity and appears to mediate the action of the zone of polarizing activity. Here we have manipulated Shh signal in the limb to assess whether it acts as a long-range signal to directly pattern all the digits. Firstly, we demonstrate that alterations in digit development are dependent upon the dose of Shh applied. DiI-labeling experiments indicate that cells giving rise to the extra digits lie within a 300 microm radius of a Shh bead and that the most posterior digits come from cells that lie very close to the bead. A response to Shh involves a 12–16 hour period in which no irreversible changes in digit pattern occur. Increasing the time of exposure to Shh leads to specification of additional digits, firstly digit 2, then 3, then 4. Cell marking experiments demonstrate that cells giving rise to posterior digits are first specified as anterior digits and later adopt a more posterior character. To monitor the direct range of Shh signalling, we developed sensitive assays for localizing Shh by attaching alkaline phosphatase to Shh and introducing cells expressing these forms into the limb bud. These experiments demonstrate that long-range diffusion across the anteroposterior axis of the limb is possible. However, despite a dramatic difference in their diffusibility in the limb mesenchyme, the two forms of alkaline phosphatase-tagged Shh proteins share similar polarizing activity. Moreover, Shh-N (aminoterminal peptide of Shh)-coated beads and Shh-expressing cells also exhibit similar patterning activity despite a significant difference in the diffusibility of Shh from these two sources. Finally, we demonstrate that when Shh-N is attached to an integral membrane protein, cells transfected with this anchored signal also induce mirror-image pattern duplications in a dose-dependent fashion similar to the zone of polarizing activity itself. These data suggest that it is unlikely that Shh itself signals digit formation at a distance. Beads soaked in Shh-N do not induce Shh in anterior limb mesenchyme ruling out direct propagation of a Shh signal. However, Shh induces dose-dependent expression of Bmp genes in anterior mesenchyme at the start of the promotion phase. Taken together, these results argue that the dose-dependent effects of Shh in the regulation of anteroposterior pattern in the limb may be mediated by some other signal(s). BMPs are plausible candidates.