Equilibrium unfolding of dimeric desulfoferrodoxin involves a monomeric intermediate: iron cofactors dissociate after polypeptide unfolding

Here we report the conformational stability of homodimeric desulfoferrodoxin (dfx) from Desulfovibrio desulfuricans (ATCC 27774). The dimer is formed by two dfx monomers linked through beta-strand interactions in two domains; in addition, each monomer contains two different iron centers: one Fe-(S-Cys)(4) center and one Fe-[S-Cys+(N-His)(4)] center. The dissociation constant for dfx was determined to be 1 microM (DeltaG = 34 kJ/mol of dimer) from the concentration dependence of aromatic residue emission. Upon addition of the chemical denaturant guanidine hydrochloride (GuHCl) to dfx, a reversible fluorescence change occurred at 2-3 M GuHCl. This transition was dependent upon protein concentration, in accord with a dimer to monomer reaction [DeltaG(H(2)O) = 46 kJ/mol of dimer]. The secondary structure did not disappear, according to far-UV circular dichroism (CD), until 6 M GuHCl was added; this transition was reversible (for incubation times of < 1 h) and independent of dfx concentration [DeltaG(H(2)O) = 50 kJ/mol of monomer]. Thus, dfx equilibrium unfolding is at least three-state, involving a monomeric intermediate with native-like secondary structure. Only after complete polypeptide unfolding (and incubation times of > 1 h) did the iron centers dissociate, as monitored by disappearance of ligand-to-metal charge transfer absorption, fluorescence of an iron indicator, and reactivity of cysteines to Ellman's reagent. Iron dissociation took place over several hours and resulted in an irreversibly denatured dfx. It appears as if the presence of the iron centers, the amino acid composition, and, to a lesser extent, the dimeric structure are factors that aid in facilitating dfx's unusually high thermodynamic stability for a mesophilic protein.

Lipid-lowering interventions in managed care settings

Effective screening, treatment, and follow-up of patients with elevated serum lipid levels is important because of the very strong association between this condition and coronary heart disease (CHD). Screening of patients with and without CHD for hyperlipidemia is not generally carried out properly by managed care organizations (MCOs) or in other settings. Primary and secondary prevention are inadequate in most patients with this condition; even in patients who are treated, lipid-lowering therapy is often not used to its full potential. These trends have been confirmed by findings in the first of a three-phase hyperlipidemia outcomes management program carried out at 27 US MCOs. The efficacy of lipid-lowering therapy can be enhanced by physician education and comprehensive, integrated quality improvement programs. The cost-effectiveness of such treatment can be improved by individualizing both drug and dose to achieve National Cholesterol Education Program goals at the lowest drug acquisition cost. The quality improvement program described and others like it have the potential to reduce the morbidity and mortality associated with CHD while decreasing the huge economic burden associated with this disease. Several such programs have been undertaken at MCOs, some with more success than others. Interventions and assessments of the type planned in phases 2 and 3 of this program can help to reduce the cost of lipid-lowering therapy without compromising cholesterol goal achievement.

Differences in the intracellular accumulation of HIV protease inhibitors in vitro and the effect of active transport

OBJECTIVES

To investigate the intracellular accumulation of HIV protease inhibitors (PI) and to assess the effect of active transport on this accumulation.

METHODS

CEM cells were incubated with a PI for 18 h and the intracellular concentration determined using cell number and radioactivity. The effect of active transport was investigated using cells expressing P-glycoprotein (CEM(VBL)) and cells expressing multidrug resistance-associated protein 1 (MRP1; CEM(E1000)). Incubations were also carried out at 4 degrees C and in the presence of 2-deoxyglucose plus rotenone to examine the effect of inhibiting active transport.

RESULTS

Nelfinavir (NFV) accumulated to the greatest extent (> 80-fold) followed by saquinavir (SQV; approximately 30-fold), ritonavir (RTV; 3-7-fold) and finally indinavir (IDV; extracellular equivalent to intracellular). In CEM(VBL) cells there was a significant reduction in the intracellular accumulation of NFV, SQV and RTV and in CEM(E1000) cells there was reduced accumulation of SQV and RTV. Inhibition of active transport processes caused a reduction in SQV and RTV accumulation but had no effect on IDV accumulation in all cell types. NFV accumulation was increased in CEM(VBL) cells as a result of inhibition of active transport.

CONCLUSIONS

Marked differences can be detected in the intracellular accumulation of HIV PI drugs in vitro. Both P-glycoprotein and MRP1 may play a role in limiting the intracellular concentration of the PI and active influx mechanisms may contribute to drug accumulation.

Social-cognitive processes in preschool boys with and without oppositional defiant disorder

The social-cognitive characteristics of 88 preschool boys with Oppositional Defiant Disorder (ODD) and 80 nondisruptive boys were assessed 3 times over a 2-year period. Three questions were addressed: (1) Do social-cognitive processes (encoding, attribution, problem solving, and response evaluation) distinguish clinic-referred preschool boys from peers without behavior problems? (2) What is the relation between preschoolers' social-cognitive processes and observed problem behavior? (3) Are the social-cognitive processes of clinic boys with ODD influenced by comorbidity with Attention Deficit Hyperactivity Disorder (ADHD)? Boys were presented hypothetical, peer-oriented social dilemmas to resolve. At all 3 assessments, clinic boys were twice as likely as were comparison group boys to generate aggressive solutions. Relative to comparison boys, clinic boys' encoding of social information was less accurate. The groups did not differ in their attributions or response evaluations. Verbal IQ and language skills were modestly correlated with problem solving and encoding. Within the clinic group, social-cognitive processes were not affected by ADHD comorbidity and they showed little relation to later diagnostic status or severity of behavior problems.

Use of pulsed-field gel electrophoresis and flagellin gene typing in identifying clonal groups of Campylobacter jejuni and Campylobacter coli in farm and clinical environments

Although campylobacters have been isolated from a wide range of animal hosts, the association between campylobacters isolated from humans and animals in the farm environment is unclear. We used flagellin gene typing and pulsed-field gel electrophoresis (PFGE) to investigate the genetic diversity among isolates from animals (cattle, sheep, and turkey) in farm environments and sporadic cases of campylobacteriosis in the same geographical area. Forty-eight combined fla types were seen among the 315 Campylobacter isolates studied. Six were found in isolates from all four hosts and represented 50% of the total number of isolates. Seventy-one different SmaI PFGE macrorestriction profiles (mrps) were observed, with 86% of isolates assigned to one of 29 different mrps. Fifty-seven isolates from diverse hosts, times, and sources had an identical SmaI mrp and combined fla type. Conversely, a number of genotypes were unique to a particular host. We provide molecular evidence which suggests a link between campylobacters in the farm environment with those causing disease in the community.

The effects of UVB and temperature on the survival of natural populations and pure cultures of Campylobacter jejuni, Camp. coli, Camp. lari and urease-positive thermophilic campylobacters (UPTC) in surface waters

AIMS

To determine whether diurnal and seasonal variations in campylobacters in surface waters result from the effects of temperature and u.v. radiation, and whether natural populations of Campylobacter lari and urease-positive thermophilic campylobacters (UPTC) from birds survive better in surface waters than Camp. jejuni from sewage.

METHODS AND RESULTS

Natural populations of Camp. lari and UPTC in sea water, and Camp. jejuni in river water, were exposed to artificial sunlight (equivalent to a sunny day in June). Both populations became non-culturable within 30 min, with T90s of 15 min and 25 min, respectively. Cultures of Camp. jejuni became non-culturable within 40 min and those of Camp. coli, Camp. lari and UPTC, within 60 min. In darkness, survival was temperature-dependent. Natural populations took 12 h at 37 degrees C and 5 days at 4 degrees C to become non-culturable in sea water, and slightly less in river water. Cultures of Camp. lari and UPTCs survived for significantly longer than Camp. jejuni and Camp. coli. Loss of culturability for all isolates was most rapid at 37 degrees C and slowest at 4 degrees C. Newly isolated strains from sea water and river water behaved in an almost identical manner to NCTC strains.

CONCLUSION

Campylobacter lari and UPTCs survive for longer in surface waters than Camp. jejuni and Camp. coli, particularly in the dark. Low Campylobacter numbers in coastal waters in the summer, especially in the afternoon, are due to the combined effects of higher temperatures and higher levels of u.v. radiation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Campylobacter lari and UPTCs from birds predominate in bathing waters in Morecambe Bay because they are better able to survive; they also originate from closer to the shore than Camp. jejuni and Camp. coli in sewage effluent, which survive poorly and die before the incoming tide reaches the shore. The predominance of Camp. jejuni in river water results from its dominance of the inputs and not from its ability to survive.

Evaluation of normal and large sphygmomanometer cuffs using the Omron 705CP

Sphygmomanometers are usually sold with a single cuff though some are supplied with a short cuff as standard and offer a longer one for larger arms. However, data on the differences in measurements taken with different cuffs applied to different sized arms are conflicting and this study set out to investigate the difference between those taken with 'normal' and 'large' cuffs in arms 28 cm or more in circumference. We avoided observer error by using a semi-automatic digital sphygmomanometer, the Omron 705CP. The 22 subjects employed were selected from one general practice as having a range of previous office blood pressures and a variety of arm sizes above 28 cm in circumference. Omron 'normal' and 'large' cuffs were used alternately, taking five blood pressures with each to a total of 30 readings per patient, resulting in 660 readings, 330 with each cuff. There were mean systolic/diastolic differences of 2.7/3.8 (s.d.s 4.7/2.8) for all subjects. These were greater in the normotensive. When divided into two groups with systolic blood pressures below and equal to or above 140 mm Hg, differences were -1.9/3.0 to 7.1/4.7. From the results of the study, we recommend that large cuffs should be used for all patients with an arm circumference of 28 cm or above but the Omron large cuff still requires formal validation.

Enteric parasitosis in northern Thailand dairy heifers and heifer calves

A cross-sectional study was designed to: (1) determine the prevalences of enteric parasitic infections in dairy heifers and heifer calves (Bos taurus) in northern Thailand, and (2) determine the risk factors associated with the observed prevalences of infection. A stratified random sample of 87 farms was selected for study, and fecal and blood samples were collected from 439 out of 450 heifers and heifer calves from these farms. Fecal samples were processed by floatation and modified Benedek sedimentation methods, and then examined microscopically for the presence of enteric parasitic ova. Complete blood counts typically were within the reference range (done using standard methods). The overall prevalence for enteric parasites in heifers and heifer calves was 54%; most were of trematodes (41%) and nematodes (26%). Risk-factors analysis at the farm level yielded no significant results. Increased age significantly increased the odds of enteric parasite infection (OR=1.02, 95% CI 1.01-1.04).

Developing a unified language for children's nurses, children and their families in the United Kingdom

This paper presents a taxonomy of Infant, Child and Adolescent (ICA) nursing diagnoses and clinical outcomes that has been developed with the co-operation of nurses caring for children in the United Kingdom. Three focus group interviews were conducted in one acute care NHS trust in London (referred to as the host trust in this paper) in 1998/99, in which participants were asked to consider nursing and family factors relevant for identifying and providing care. A total of 28 ICA diagnoses, including definitions, defining characteristics and outcomes, were identified for clinical testing and included in the ICA taxonomy. The ICA diagnostic labels and outcomes for care were further tested for their relevance for clinical practice in a Delphi Survey carried out in 1999 and their use in clinical practice began in 1999. This research augments the findings from an initial Delphi survey carried out in 1993 and case study research in 1996. The previous research initiated the development of a unified language for children's nurses, children and their families, to aid communication and decision-making. Implications of this and future research for clinical practice, nationally and internationally, are also discussed.

Effect of alpha1-acid glycoprotein on the intracellular accumulation of the HIV protease inhibitors saquinavir, ritonavir and indinavir in vitro

AIMS

Since alpha1-acid glycoprotein (AGP) levels may be raised during HIV infection, we have examined in vitro the effect of increasing the concentration of AGP on the intracellular accumulation of the HIV protease inhibitors saquinavir (SQV), ritonavir (RTV) and indinavir (IDV).

METHODS

U937 cells (5 x 10(6) cells in 5 ml RPMI growth medium) were incubated at 37 degrees C for 18 h with [14C]-SQV (0.1 microCi), [3H]-RTV and [3H]-IDV (0.135 microCi) to a final concentration of 1 microM in the presence of 0, 0.5 and 2.0 mg x ml(-1) AGP. Following extraction in 60% methanol the intracellular drug concentration was determined by liquid scintillation counting.

RESULTS

Binding to AGP (2.0 mg x ml(-1)) reduced the mean intracellular concentration of SQV from 31.5 microM to 7.4 microM (P < 0.0001; 95% CI 19.4-28.8). RTV concentration was also reduced (8.8 microM to 1.6 microM; P < 0.0001; 95% CI 5.4-9.0) as was the concentration of IDV (3.0 microM to 1.5 microM; P < 0.0001; 95% CI 1.1-1.9).

CONCLUSIONS

Reduced intracellular protease inhibitor concentrations in the presence of increasing concentrations of AGP will certainly impact on the antiviral activity in vitro. However, since protease inhibitors are high clearance drugs, free drug concentration will likely remain unaffected in the presence of elevated AGP during chronic oral dosing although there will be an increase in total plasma drug concentration.

Evidence for placental abnormality as the major cause of mortality in first-trimester somatic cell cloned bovine fetuses

The production of cloned animals is, at present, an inefficient process. This study focused on the fetal losses that occur between Days 30-90 of gestation. Fetal and placental characteristics were studied from Days 30-90 of gestation using transrectal ultrasonography, maternal pregnancy specific protein b (PSPb) levels, and postslaughter collection of fetal tissue. Pregnancy rates at Day 30 were similar for recipient cows carrying nuclear transfer (NT) and control embryos (45% [54/120] vs. 58% [11/19]), although multiple NT embryos were often transferred into recipients. From Days 30-90, 82% of NT fetuses died, whereas all control pregnancies remained viable. Crown-rump (CR) length was less in those fetuses that were destined to die before Day 90, but no significant difference was found between the CR lengths of NT and control fetuses that survived to Day 90. Maternal PSPb levels at Days 30 and 50 of gestation were not predictive of fetal survival to Day 90. The placentas of six cloned and four control (in vivo or in vitro fertilized) bovine pregnancies were compared between Days 35 and 60 of gestation. Two cloned placentas showed rudimentary development, as indicated by flat, cuboidal trophoblastic epithelium and reduced vascularization, whereas two others possessed a reduced number of barely discernable cotyledonary areas. The remaining two cloned placentas were similar to the controls, although one contained hemorrhagic cotyledons. Poor viability of cloned fetuses during Days 35-60 was associated with either rudimentary or marginal chorioallantoic development. Our findings suggest that future research should focus on factors that promote placental and vascular growth and on fetomaternal interactions that promote placental attachment and villous formation.

Environmental Accountability: Who's Kidding Whom?

International declarations and charters have been produced to encourage and support higher education institutions (HEIs) to address their environmental responsibilities. This paper discusses the results of a critical examination of a range of international HEIs that have signed the global environmental Talloires Declaration. It also assesses the Talloires Secretariat (University Leaders for a Sustainable Future, ULSF) and the extent to which this has been a primary stimulus. An international survey was undertaken and the results presented in a discursive format in order to highlight key driving forces, barriers, and opportunities for environmental responsibility in HEIs. Analysis reveals that they occur on two distinct and evolving levels: the macro national framework level and the micro institutional framework level. Survey responses revealed that none of the HEIs have an embedded institutional environmental culture and most did not have all the micro institutional mechanisms in place for an integrated university-wide environmental response. Many of the institutional barriers to environmental responsibility occurred as a result of this lack of strategy. The most significant institutional opportunity cited was enthusiastic individuals, particularly those at senior management or directorate level, and these individuals were found to be a key driving force. Results also showed that environmental reporting along the lines developed by the private sector is a flexible mechanism that can stimulate progress internally and externally and can be cost effectively disseminated via the World Wide Web. Moreover the survey results indicate that ULSF is not currently a primary stimulus for institution wide action.

Prevalence of headaches in football players

BACKGROUND

Football coaches and team physicians rely heavily on players' reports of symptoms in deciding whether a player may return to the game after sustaining head trauma. The decision is made difficult by the wide variety of associated symptoms, some of which (e.g., headache is among the most common) may or may not be associated with serious head injury. More information is needed about the clinical significance of football-related headache.

METHODS

To assess the frequency of headache associated with playing football, we analyzed responses to our questionnaire asking about incidence, frequency, and outcome of football-related headache from 443 football players (320 from college, 123 from high school).

RESULTS

Eighty-five percent of respondents reported previous headache related to hitting in football. Asked specifically about their most recent game, 21% of respondents reported having had headache during that game. Of players who had headache, only 19% informed the team physician, trainer, or coach, and only 6% were removed from the game. Twenty-seven percent of respondents reported previous diagnosis of cerebral concussion by medical personnel. Defensive backs (25%), defensive linemen (19%), and offensive linemen (18%) were most likely to have headache, related to hitting.

CONCLUSIONS

Our data confirm that posttraumatic headache is commonly associated with football participation and often goes unreported. Given that the most serious complications of head injuries (e.g., second-impact syndrome) occur infrequently, headache as an isolated symptom lacks specificity in predicting such complications in football players. Therefore, unless it persists or is accompanied by additional symptoms, headache alone may not reliably suggest the need to remove players from the game.

Structure-based design and synthesis of phosphinate isosteres of phosphotyrosine for incorporation in Grb2-SH2 domain inhibitors. Part 2

A series of novel phosphinates, derived from 4-phosphonomethylphenylalanine, are described as isosteres of phosphotyrosine. Benzyl (or alkyl) phosphinomethylphenylalanine derivatives were prepared by alkylation of an amino acid P-H phosphinate.

Dialogues in the exam room: medical interviewing by resident family physicians

BACKGROUND

Limited information exists about the application of the biopsychosocial model in medical practice. This study expanded our knowledge about the extent to which psychosocial content is included in medical interviews conducted by resident family physicians.

METHODS

Interviews of 180 patients conducted by six second-year family practice residents were audiotaped and transcribed. Physician statements were analyzed and coded as social talk, physician-centered statements, patient-centered statements, and discussion of patient affect, family, health promotion, and patient education.

RESULTS

The proportion of interviews in which specific physician interactions occurred were physician-centered statements: 100%, patient-centered statements: 66%, dealing with patient affect: 18%, information about family: 61%, initiation of health promotion: 33%, and initiation of patient education: 46%. Discussions of patient opinion/perception, patient affect, family information, and health promotion occurred most commonly during well-care visits and with female patients.

CONCLUSIONS

In this sample of residents, providers extended the interview beyond a purely biomedical focus. However, the psychosocial focus often was brief and applied inconsistently across patients.

Accuracy of cyclosporin measurements made in capillary blood samples obtained by skin puncture

International consensus guidelines suggest that cyclosporin should be measured in whole blood. In some instances it may be advantageous to collect capillary blood, by a finger or ear prick method. However, drug concentrations in skin-puncture blood may not necessarily correlate with those measured in venous blood. This study compared cyclosporin concentrations in blood collected from the fingertip or earlobe with blood collected by standard venipuncture. Patient preference for each of the blood collection methods was also assessed. Specimens were obtained from organ transplant patients receiving cyclosporin, using each of the three methods: venipuncture, finger prick, and earlobe prick. The samples were assayed using a specific radioimmunoassay and the results were compared. In the 102 sets of samples collected, the mean difference (+/- standard deviation) in cyclosporin concentration between finger prick and venipuncture and ear prick and venipuncture was 2.6% (+/- 9.5%) and 2.7% (+/- 12.1%), respectively, while the comparable median (IQR) differences were 1.9% (-3.4% to +6.6%) and -1.1% (-2.8% to +7.2%), respectively. A high degree of correlation was observed between finger prick and venipuncture or ear prick and venipuncture or ear prick and finger prick (r2 > 0.86). Of the three methods of blood collection, finger prick was the patients' preferred method (P < 0.01). These data suggest that capillary blood collected by skin puncture is suitable for use in cyclosporin blood monitoring and acceptable to patients.

Consumed with worry: 'unsafe' alcohol consumption and self-reported problem drinking in England

Using data from the 1994 Health Survey for England, logistic multivariate multilevel modelling techniques are used to investigate the simultaneous effect of individual demographic characteristics and socio-structural factors on self-reported problem drinking as revealed by CAGE scores and 'unsafe' levels of alcohol consumption. Whilst the influence of key socio-structural variables is broadly similar for both unsafe alcohol consumption and high CAGE scores, there are notable exceptions when results are examined by tenure group: those in the rented sector are more likely to be problem drinkers as revealed by CAGE, but less likely to consume 'unsafe' amounts of alcohol. Both dimensions of drinking behaviour are influenced by the consumption patterns of others in the household, with both likelihoods increasing as the average consumption of others in the household rises. After taking into account individual compositional variables, the research indicates that there is very little evidence for geographical variation remaining in these two dimensions of drinking behaviour. It is found that the proportion of the population whose drinking behaviour may be classed as (potentially) problematic via the CAGE responses is substantially less than the proportion consuming above recommended 'safe' levels. The research concludes, however, that the two measures are broadly similar in their relationship to social and structural variables. Tenure provides an exception to this conclusion and indicates a continuing need to take account of housing circumstances in developing an understanding of drinking behaviour.

Impact of synthetic pyrethroid-sheep dip on the indigenous microflora of animal slurries

The chemical constituents of sheep dip in the UK are currently changing from organophosphate-based to synthetic pyrethroid-based insecticides. As a result, changes are also being made to the methods of disposal of these chemicals in the environment, such that pyrethroid sheep dips must now be diluted in animal slurry or water. To date, there is a lack of quantitative information on the impact of the insecticide on the indigenous microflora of animal slurries. This paper investigated the impact of Bayticol (synthetic pyrethroid sheep dip) over a range of concentrations on selected populations of bacteria within animal slurry. It was found that, with increasing pesticide concentration, there was up to a four orders of magnitude increase in the numbers of faecal coliforms and pathogens, such as putative Salmonella spp. These findings have implications for the disposal of sheep dip-amended animal slurries to land from several aspects: (i) the longevity of putative pathogens in the field may require re-evaluation of the time required before the return of grazing livestock to a slurry-amended field; (ii) the potential for the transfer of pathogenic bacteria and faecal coliforms into human and animal foodchains, and (iii) the increased potential for faecal coliforms being washed into streams, rivers and coastal bathing waters.

Interaction of the U3-55k protein with U3 snoRNA is mediated by the box B/C motif of U3 and the WD repeats of U3-55k

U3 small nucleolar RNA (snoRNA) is a member of the Box C/D family of snoRNAs which functions in ribosomal RNA processing. U3-55k is a protein that has been found to interact with U3 but not other members of the Box C/D snoRNA family. We have found that interaction of the U3-55k protein with U3 RNA in vivo is mediated by the conserved Box B/C motif which is unique to U3 snoRNA. Mutation of Box B and Box C, but not of other conserved sequence elements, disrupted interaction of U3-55k with U3 RNA. Furthermore, a fragment of U3 containing only these two conserved elements was bound by U3-55k in vivo. RNA binding assays performed in vitro indicate that Box C may be the primary determinant of the interaction. We have cloned the cDNA encoding the Xenopus laevis U3-55k protein and find strong homology to the human sequence, including six WD repeats. Deletion of WD repeats or sequences near the C-terminus of U3-55k resulted in loss of association with U3 RNA and also loss of localization of U3-55k to the nucleolus, suggesting that protein-protein interactions contribute to the localization and RNA binding of U3-55k in vivo.