The SufE protein and the SufBCD complex enhance SufS cysteine desulfurase activity as part of a sulfur transfer pathway for Fe-S cluster assembly in Escherichia coli

The sufABCDSE operon of the Gram-negative bacterium Escherichia coli is induced by oxidative stress and iron deprivation. To examine the biochemical roles of the Suf proteins, we purified all of the proteins and assayed their effect on SufS cysteine desulfurase activity. Here we report that the SufE protein can stimulate the cysteine desulfurase activity of the SufS enzyme up to 8-fold and accepts sulfane sulfur from SufS. This sulfur transfer process from SufS to SufE is sheltered from the environment based on its resistance to added reductants and on the analysis of available crystal structures of the proteins. We also found that the SufB, SufC, and SufD proteins associate in a stable complex and that, in the presence of SufE, the SufBCD complex further stimulates SufS activity up to 32-fold. Thus, the SufE protein and the SufBCD complex act synergistically to modulate the cysteine desulfurase activity of SufS. We propose that this sulfur transfer mechanism may be important for limiting sulfide release during oxidative stress conditions in vivo.

Staphylococcus lugdunensis vertebral osteomyelitis

We report a case of vertebral osteomyelitis due to the coagulase-negative staphylococcus, Staphylococcus lugdunensis. This is only the second such case reported in the literature in an immunocompetent host. When the patient's lumbar spine inflammatory mass was drained, the coagulase-negative staphylococcus obtained was discarded as a likely contaminant. We discuss the situation when coagulase-negative staphylococci require further identification and look at the unique features of S. lugdunensis. Isolation of S. lugdunensis is usually significant, and the organism should not be discarded as a contaminant without careful consideration.

The Redox Domain of the Yap1p Transcription Factor Contains Two Disulfide Bonds

The subcellular localization of the Saccharomyces cerevisiae transcription factor Yap1p is regulated by oxidation and reduction. We purified Yap1p from yeast and characterized its properties in vitro. Electrophoretic mobility shift assays showed that the purified protein can specifically bind the TRX2 target promoter. Yap1p was purified under reducing conditions, but removal of reducing agents resulted in the formation of an oxidized Yap1p species with properties similar to in vivo oxidized Yap1p. MALDI-TOF mass spectrometry analysis revealed that the oxidized form of Yap1p contains two disulfide bonds between C303-C598 and C310-C629. A stable domain of approximately 15 kDa was detected upon limited proteolysis of oxidized but not reduced Yap1p. This Yap1p protease resistant domain was purified, and MALDI-TOF mass spectrometry analysis showed that it was comprised of two separate cysteine-containing peptides of Yap1p. These peptides are separated by 250 amino acids and are joined by the C303-C598 and C310-C629 disulfide bonds. Taken together, these data suggest that the domain that controls Yap1p subcellular localization is modular and contains a redox center comprised of four cysteine residues.

Ribozymes and siRNA for the treatment of diseases of the nervous system

Recent advances in our understanding of RNA biology have focused attention on the potential of developing RNA-based strategies to treat human disease. Naturally occurring catalytic RNA molecules (ribozymes), their synthetic DNA counterparts (deoxyribozymes or DNAzymes), as well as the exciting, emerging technology of small interfering RNA which utilizes the highly conserved cellular RNA interference pathway, are being developed for therapeutic gene silencing purposes. The challenges for the application of this technology to neurological disease will be to identify appropriate disease targets, and to optimize the function, and particularly delivery of these RNA-based therapeutic molecules within the complex environment of the nervous system. This review will assess the potential of these RNA-based therapeutic strategies and the challenges ahead in their application to the treatment of neurological disease.

Conformational dimorphism and transmembrane orientation of prion protein residues 110-136 in bicelles

A fragment corresponding to the putative membrane-associating domain of the prion protein (residues 110-136) was analyzed in phospholipid bicelles. Prion(110-136) associated with bicelles and exhibited a lipid- and pH-dependent conformational dimorphism between unstructured (pH 4.5) and alpha-helical (pH 7.5). Mutational analysis indicated that the charge state of a single histidine residue was largely responsible for the dimorphism. Amide-lipid NOEs and amide-water chemical exchange measurements revealed that the helical conformation of prion(110-136) spanned the bilayer, and were corroborated by solid-state deuterium NMR experiments indicating that the helical axis rested at a 16 degrees angle with respect to the bilayer normal.

Sociodemographic characteristics associated with medical appointment adherence among HIV-seropositive patients seeking treatment in a county outpatient facility

BACKGROUND

Adherence is a major problem facing HIV-seropositive patients. Low adherence has been associated with faster disease progression as well as development of drug-resistant strains of HIV. Thus it is critical to understand factors associated with treatment compliance. This study examined the independent contributions of disease severity, age, gender, household income, homelessness, ethnicity, and sexual orientation on appointment adherence.

METHODS

Participants (n = 671) scheduled for appointments in an outpatient county treatment facility for HIV-related medical care completed demographic questionnaires and clinic staff collected appointment attendance data.

RESULTS

Multiple regression analyses indicated that patients diagnosed with AIDS, older in age, and receiving a higher income were more likely to keep medical appointments. Additionally, African American ethnicity and identifying as heterosexual were associated with missing scheduled medical appointments.

CONCLUSIONS

These data suggest that cultural and sociodemographic characteristics influence patients' adherence to outpatient services. Implications for interventions aimed at increasing medical adherence are discussed.

Comparison of efficacy of ginger with various antimotion sickness drugs

Ginger and several other medications were compared with scopolamine and d-amphetamine for effectiveness in prevention of motion sickness.

METHODS

Double-blind techniques were used. The subjects were given the medications two hours before they were rotated in a chair making head movements until a symptom total short of vomiting was reached. Standardized N.A.S.A. techniques were used for speed of rotation and end-point of motion sickness.

RESULTS

The three doses of ginger were all at the placebo level of efficacy. Amitriptyline, ethopropazine and trihexyphenidyl increased the tolerated head movements but the increase was not statistically significant. Significant levels of protection were produced by dimenhydrinate, promethazine, scopolamine and d-amphetamine. Protection was further increased by combination of these latter drugs with d-amphetamine. Efficacy was greatest as the dose was increased.

CONCLUSIONS

The medication of choice in this study was scopolamine 0.6 mg with d-amphetamine 10 mg. This combination provided good protection with acceptable side effects.

Phase specific analysis of herpes zoster associated pain data: a new statistical approach

Herpes zoster or shingles is a frequent occurrence in both elderly individuals and immunocompromised hosts. The pain associated with herpes zoster is the most debilitating complication of the disease. It can be described as acute pain and post-herpetic neuralgia or zoster associated pain (ZAP). The latter definition encompasses pain from the onset of disease through its resolution and provides a convenient analytic tool for evaluation of antiviral therapy. A heuristic examination of ZAP historical data suggests the existence of three phases of pain resolution: the acute, subacute and chronic phases. The subacute and chronic phases comprise the post-herpetic neuralgia (PHN) stage. Common analytic methods, such as a Kaplan-Meier survival function or a Cox's model, have been used to assess the pain. However, such approaches do not adequately allow for phase comparison. Notably, in the clinical trial setting the comparison of specific treatment effects on the latter stages of pain are of the greatest medical relevance since this is the most debilitating phase of the illness. In order to incorporate the phase-specific information in the modelling of time to cessation of ZAP, we assumed the hazard function was a stepwise constant. Utilizing the full likelihood function, we obtained the maximum likelihood estimate for the transition times (that is, change-points), and other parameters of medical importance. The standard error of the change-point estimates were obtained through a bootstrapping method. The asymptotic properties of the parameter estimates are also discussed. Hence, the rates of pain resolution across all phases can be examined in order to precisely define the existence of multiple phases. In addition, the covariates effect can be examined across phases and populations, thereby allowing us to translate potential efficacy of a standard therapy to different populations. These results can be utilized in the design of clinical trials or in targeting the outcome for a specific phase while controlling for the effect of other variables.

Declining clinical autopsy rates versus increasing medicolegal autopsy rates in Halifax, Nova Scotia

The downward trend in the rate of clinical autopsies has been extensively documented in the literature. This decline is of concern when the benefits of the clinical autopsy are considered. In contrast, the rate of medicolegal autopsies has not been studied in such detail. What little reference there is to medicolegal autopsy rates suggests an absence of the same downward trend. A retrospective review of autopsy data over a 13-year period from the Queen Elizabeth II Health Sciences Centre in Halifax, Nova Scotia, and from the Office of the Chief Medical Examiner of Nova Scotia was conducted. This review showed a difference between the rates of clinical and medicolegal autopsies for the metro Halifax area. The clinical autopsy rate was consistently less than 30% and declined to 15% in 1999, while the medicolegal autopsy rate was consistently greater than 40% and rose to 62% in 1999. The literature proposes many reasons for the decline in the clinical autopsy rate, but none for this difference between rates. The explanation proposed here is the changing and currently uncertain purpose of the clinical autopsy versus the clear, and consistent over time, purpose of the medicolegal autopsy.

Comparative safety of teicoplanin and vancomycin

Although modern preparations of vancomycin are associated with a lower incidence of adverse events than the early preparations, a number of clinically significant problems remain. Consequently monitoring of serum concentrations is required. In a meta-analysis of comparative trials adverse events were significantly less likely to occur with teicoplanin (13.9%) than with vancomycin (21.9%) (P = 0.0003). This was particularly significant when nephrotoxicity was considered: 4.8% vs. 10.7%, for teicoplanin and vancomycin, respectively (P = 0.0005). Red man syndrome, which may be due to histamine release, occurs after rapid infusion of vancomycin but is very rare following teicoplanin administration. In USA trials, thrombocytopenia was more commonly seen with teicoplanin administration but this was almost exclusively in patients receiving much larger doses than are now recommended. The lower rate of adverse events supports the choice of teicoplanin over vancomycin in treating infections where the two antibiotics have similar efficacy.

Two mechanisms of K(+)-dependent potentiation in Kv2.1 potassium channels

Elevation of external [K(+)] potentiates outward K(+) current through several voltage-gated K(+) channels. This increase in current magnitude is paradoxical in that it occurs despite a significant decrease in driving force. We have investigated the mechanisms involved in K(+)-dependent current potentiation in the Kv2.1 K(+) channel. With holding potentials of -120 to -150 mV, which completely removed channels from the voltage-sensitive inactivated state, elevation of external [K(+)] up to 10 mM produced a concentration-dependent increase in outward current magnitude. In the absence of inactivation, currents were maximally potentiated by 38%. At more positive holding potentials, which produced steady-state inactivation, K(+)-dependent potentiation was enhanced. The additional K(+)-dependent potentiation (above 38%) at more positive holding potentials was precisely equal to a K(+)-dependent reduction in steady-state inactivation. Mutation of two lysine residues in the outer vestibule of Kv2.1 (K356 and K382), to smaller, uncharged residues (glycine and valine, respectively), completely abolished K(+)-dependent potentiation that was not associated with inactivation. These mutations did not influence steady-state inactivation or the K(+)-dependent potentiation due to reduction in steady-state inactivation. These results demonstrate that K(+)-dependent potentiation can be completely accounted for by two independent mechanisms: one that involved the outer vestibule lysines and one that involved K(+)-dependent removal of channels from the inactivated state. Previous studies demonstrated that the outer vestibule of Kv2.1 can be in at least two conformations, depending on the occupancy of the selectivity filter by K(+) (Immke, D., M. Wood, L. Kiss, and S. J. Korn. 1999. J. Gen. Physiol. 113:819-836; Immke, D., and S. J. Korn. 2000. J. Gen. Physiol. 115:509-518). This change in conformation was functionally defined by a change in TEA sensitivity. Similar to the K(+)-dependent change in TEA sensitivity, the lysine-dependent potentiation depended primarily (>90%) on Lys-356 and was enhanced by lowering initial K(+) occupancy of the pore. Furthermore, the K(+)-dependent changes in current magnitude and TEA sensitivity were highly correlated. These results suggest that the previously described K(+)-dependent change in outer vestibule conformation underlies the lysine-sensitive, K(+)-dependent potentiation mechanism.

HRT to prevent cardiovascular disease. What studies show, how to advise patients

How should you advise postmenopausal patients who are considering estrogen therapy? Do the potential cardiovascular benefits outweigh the risks? Does hormone therapy improve the cardiovascular risk profile in women with established coronary artery disease? In this article, Drs Wood and Cox help clarify the current clinical data for and against hormone replacement therapy for prevention of cardiovascular disease. In addition, they discuss current treatment recommendations and future directions in hormone therapy.

Preface

Although the clinical presentation and the treatment of lower urinary tract infection (UTI) have changed little in the 60 to 70 years of the 'antibiotic era', uropathogenic bacteria have not been slow to respond to the selecting pressure of antimicrobials. This is because such infections are common. Approximately 3% of all consultations made to general practitioners are for symptoms of UTI and approximately 12-20% of all antibiotic prescriptions are for this indication. Between one-quarter and one-half of all women experience a UTI at some time. The problem, therefore, is a considerable one and warrants reevaluation. This supplement is based upon papers presented at a meeting held in March 2000 in Vienna, Austria and sponsored by Leo Pharmaceutical Laboratories. It draws together the current views on the diagnosis and the treatment of UTIs at a time when the disease-causing microorganisms are most certainly changing. Antibiotic resistance to commonly used agents, such as trimethoprim and ampicillin, often now exceeds 30-50%. The clinician may be tempted to choose an agent such as a fluoroquinolone for the treatment of this disease, yet it is known that fluoroquinolone resistance can develop rapidly. Views on the length of treatment have also changed over the years and a 3 day regimen is usually now advocated. Pivmecillinam, which is hydrolysed to mecillinam after absorption, has a novel mode of action, rapid bacterial cell penetration and lower affinity for common beta-lactamases. Its spectrum of activity and good safety profile make it an ideal candidate for the treatment of this common condition. Experience in several countries over many years confirms this assessment and it may be time to reconsider the potential role of pivmecillinam in the treatment of UTIs. The Editors would like to thank Inge Boe and Paul Menday of Leo Laboratories for their untiring support and assistance in the preparation of this supplement.

Health promotion and senior women with limited incomes

Health promotion is increasingly being recognized as making an important contribution to the well-being of Canada's seniors. Most research relating to this topic, however, has focused on middle-income senior men and women. An exploratory study using ethnographic methods was conducted to explore and describe the health promotion experience of senior women living on limited incomes. Interviews with a total of 11 urban senior women living on limited incomes were analyzed. A major finding of this study was that the women utilized a wide variety of "ways of living" that are presented in the model, Health Promotion as Self Nurturance. Health promotion was perceived to be influenced by living on a limited income by most participants; however, 3 of the participants believed that their health status and income level were unrelated. Findings are discussed and implications for community health nurses are offered.

Restoration of a normal reproductive lifespan after grafting of cryopreserved mouse ovaries

Fresh and frozen ovaries from 10 day old C57BL/6J-Gpi-1(a) mice were grafted orthotopically into ovariectomized B6CBF1 (homozygous Gpi-1(b)) recipients. The recipients were mated with B6CBF1 males. The birth and size of each litter was recorded. The electrophoretic variant of glucose phosphate isomerase was determined for each neonate. Twelve of 13 recipients of fresh ovary and 10 of 12 recipients of frozen ovary were fertile. Of these, 10 (fresh) and eight (frozen) had litters derived from the ovarian grafts only, or from the graft and native ovary. The breeding characteristics of recipients of fresh and frozen grafts were similar. The reproductive lifespan of the recipients of fresh (6.2 litters) and frozen (8.4 litters) grafts was similar to that of unoperated C57BL/6-Gpi-1(a) control females mated with B6CBF1 males (6.3 litters). Litter size was similar in recipients of grafted ovaries (fresh, 5.4 pups/litter; frozen, 6.3 pups/litter) and C57BL/6-Gpi-1(a) females (6.3 pups/litter). The results suggest that cryopreservation per se does not affect the long-term viability of ovarian tissue and provides an option for storing female germ cells. This is the first unequivocal demonstration that a normal reproductive lifespan can be restored by orthotopic grafting of frozen ovary.

The prevalence and ecology of the haematozoan parasites of European blackbirds, Turdus merula

The prevalence and ecology of the haematozoan parasites of a rural population of European blackbirds, Turdus merula, were investigated. Parasites belonging to eight species from four genera (Leucocytozoon, Plasmodium, Haemoproteus, and Trypanosoma) were identified. Prevalence was high: 83% of adults and 80% of juveniles were infected by at least one species of haematozoa, but no parasites were detected in 8-day-old nestlings. There were no sex differences in infection rates and only Plasmodium infection varied with age among adult blackbirds. Haemo proteus infections increased and Plasmodium infections decreased through the sampling period (January to July), but infections with other haematozoa showed no seasonal change. Haemoproteus and Plasmodium were negatively associated with each other, even during the period when infections by both genera were frequent in the study population.

Prokinetic effects of erythromycin after antimotion sickness drugs

Motion sickness and the antimotion sickness drugs scopolamine (SCP) and promethazine (PMZ) inhibit gastric emptying (GE). This study was conducted to determine if erythromycin would exert its well-known prokinetic effects in normal and motion-sick subjects given antimotion sickness drugs. Fifteen fasted volunteers (11 males, 4 females) participated in the study. In control tests, 8 subjects were given intramuscular (i.m.) saline (SAL, 0.5 ml), SCP (0.1 mg), or PMZ (25 mg). GE of liquid (300 ml) containing 1 mCi of Tc 99m diethylenetriaminepentaacetic acid (DTPA) was measured by sequential gastric scintigraphy 30 minutes after i.m. treatments. In other tests, GE was measured in 8 subjects after each i.m. treatment, followed 10 minutes later by 200 mg of erythromycin ethylsuccinate (ESS) suspension given orally. In a third group of tests, 7 subjects received an i.m. treatment, oral EES 10 minutes later, and were then brought to an advanced level of motion sickness short of vomiting. To induce motion sickness, blindfolded subjects made timed head movements while seated in a rotating chair. GE was measured immediately after rotation. GE half-life, rate constant, area under the curve (AUC), and lag time were calculated using conventional mathematical methods for analyzing exponential rate processes. GE parameters calculated for normal and motion-sick subjects given antimotion sickness drugs and EES were compared with those from subjects given i.m. treatments (control) only. In normal subjects, EES significantly (p < 0.05) increased the GE rate constant for all i.m. treatments and reduced the AUC for SAL, SCP, and PMZ by 49% (p < 0.05), 44% (p < 0.05), and 69% (p < 0.01), respectively. In motion-sick subjects, lag time was significantly (p < 0.05) increased, and the rate constant and AUC values were unchanged from control for all i.m. treatments. The authors conclude that oral EES reverses the gastrostatic actions of the antimotion sickness drugs but does not affect the inhibition of gastric emptying associated with motion sickness. The results suggest that motion sickness and antimotion sickness drugs reduce GE through different mechanisms.

Solution structure of the smallest cofactor-active fragment of thrombomodulin

A glycosylated fragment of thrombomodulin containing two epidermal growth factor-like domains (TMEGF45) was analyzed by NMR. The 4th-domains structure of this two-domain fragment is similar to that of the individual domain previously determined. The 5th-domain, which has uncrossed disulfide bonds, is not as well determined in the two-domain fragment than the individual domain previously solved. The flexibility of the 5th-domain is consistent with low heteronuclear NOEs. In the individual 5th-domain, Met 388 was disordered, and key thrombin binding residues formed a hydrophobic core. By contrast, in TMEGF45, Met 388 is in the 5th-domain core, positioned by Phe 376 from the 4th-domain. As a result, key thrombin binding residues that were in the core of the individual domain are expelled. Upon thrombin binding, chemical shifts of two residues in the 4th-domain, the three interdomain linker residues, and nearly all of the 5th-domain are perturbed. Thus, TMEGF45 binds thrombin by an induced fit mechanism involving a flexible 5th-domain.

Humoral immune responses to adenovirus vectors in the brain

We have investigated the humoral immune response to E1-deleted adenovirus vectors encoding the lacZ gene introduced into the brains of mice. Injection of these non-replicating vectors into the brain induced systemic antibody production to adenovirus vectors in dose dependent manner. Apparent antibody production to beta-galactosidase, the product of the lacZ gene, was detected later than anti-adenovirus antibody. Neutralizing antibody was not detected. This study demonstrates that E1-deleted adenovirus vectors injected into the brain trigger humoral immune responses to the adenovirus and its gene products, but they are not sufficient to block the infection of cells by adenovirus upon repeat injection.

Prevention of the dystrophic phenotype in dystrophin/utrophin-deficient muscle following adenovirus-mediated transfer of a utrophin minigene

Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disorder caused by the lack of a subsarcolemmal protein, dystrophin. We have previously shown that the dystrophin-related protein, utrophin is able to compensate for the lack of dystrophin in the mdx mouse, the mouse model for DMD. Here, we explore whether utrophin delivered to the limb muscle of dystrophin/utrophin-deficient double knockout (dko) neonatal mice can protect the muscle from subsequent dystrophic damage. Utrophin delivery may avoid the potential problems of an immune response associated with the delivery of dystrophin to a previously dystrophin-deficient host. Dko muscle (tibialis anterior) was injected with a first generation recombinant adenovirus containing a utrophin minigene. Up to 95% of the fibres continued expressing the minigene 30 days after injection. Expression of utrophin caused a marked reduction from 80% centrally nucleated fibres (CNFs) in the uninjected dko TA to 12% in the injected dko TA. Within the region of the TA expressing the utrophin minigene, a significant decrease in the prevelance of necrosis was noted. These results demonstrate that the utrophin minigene delivered using an adenoviral vector is able to afford protection to the dystrophin/utrophin-deficient muscle of the dko mouse. Gene Therapy (2000) 7, 201-204.

Chemotherapy for gram-positive nosocomial sepsis

Over recent years gram-positive bacterial pathogens have become dominant in many forms of nosocomial infections. The principal pathogens in severe infections are Staphylococcus aureus and enterococci. The utility of the traditional antibiotics used for nosocomial sepsis, particularly beta-lactam agents, has been severely compromised by the spread of resistance and there was, often, no therapeutic alternative to the glycopeptide antibiotics, vancomycin and teicoplanin, for empirical (and often also the specific) therapy of infections caused by methicillin-resistant S. aureus (MRSA) and Enterococcus spp. This reliance on glycopeptides, however, is now also threatened by acquired resistance. Vancomycin-resistant enterococci (VRE), particularly E. faecium, have become a therapeutic problem in many European cities and are now endemic in some hospital wards. The recent reports from several continents of MRSA with reduced glycopeptide-susceptibility (GISA) is of grave concern. New agents are needed to meet these threats and several classes of compounds are under development. One class is the streptogramins and the combination of quinupristin/dalfopristin (Synercid) is nearing licensing. Clinical trials and a compassionate use programme have already shown it to have considerable promise for the treatment of the most problematic forms of gram-positive nosocomial sepsis, including MRSA and vancomycin-resistant E. faecium infections that had failed therapy with other antibiotics.