Why do cytotoxic T lymphocytes fail to eliminate hepatitis C virus? Lessons from studies using major histocompatibility complex class I peptide tetramers

Hepatitis C virus (HCV) infection is a major public health problem, affecting an estimated 3% of the world's population, and over 10% in some countries. Infection in most cases becomes persistent, and can lead to hepatic inflammation, fibrosis and liver failure. The T lymphocyte reponse, in particular that mediated by cytotoxic T lymphocytes (CTLs), is likely to be involved in determining the outcome of infection, although its overall role is not clear. The use of major histocompatibility complex (MHC) class I peptide tetrameric complexes (tetramers) to study antiviral CTL responses has revolutionized our approach to the study of human infection. We have used a panel of MHC class I tetramers to analyse immune responses in HCV-infected individuals at various stages of disease. We find that the CTL response against HCV is vigorous in its early phases but dwindles over time both in terms of lymphocyte number and function. A number of potential explanations for this 'CTL failure' are discussed.

Tomographic imaging of foam

The morphology of three-dimensional foams is of interest to physicists, engineers, and mathematicians. It is desired to image the 3-dimensional structure of the foam. Many different techniques have been used to image the foam, including magnetic resonance imaging, and short-focal length lenses. We use a camera and apply tomographic algorithms to accurately image a set of bubbles. We correct for the distortion of a curved plexiglas container using ray-tracing.

Positioning of patients with severe traumatic brain injury: research-based practice

Traumatic brain injuries (TBIs) are the most common disabling injuries in the United States, accounting for 44% of all deaths due to trauma. Once inflicted, primary cerebral injury is immutable and irreversible. Consequently, initial critical care of TBI patients focuses on prevention of secondary cerebral injury through the treatment of intracranial hypertension, systemic resuscitation, and multisystem stabilization. Relationships exist between therapeutic positioning, multisystemic stability, and prevention of secondary cerebral injury in severe TBI. A critical review and synthesis of current research literature on multisystem responses to positioning led to development of clinical recommendations based on currently available evidence and generated best practices for positioning patients with severe TBI.

Nursing scripts and the organizational influences on critical thinking: report of a study of neonatal nurses' clinical reasoning

During 1995-1997 a study was undertaken to explore the extent to which theoretical knowledge acquired through a distance education programme in neonatal nursing was brought to bear in the real-world clinical reasoning of course participants. The study utilized a think aloud technique and included both concurrent (on-the-job) and retrospective verbal reports at 0, 6 and 12 months into the programme. Participants (n=4) were also interviewed individually on completion of the study. Results indicated that important inconsistencies existed between participants' theoretical knowledge and their practice; they also pointed to some organizational influences on these theory-practice inconsistencies. Script (or schema) theory provided a useful explanatory framework for these results. The paper includes a brief description of data collection and analysis techniques; its main emphasis, however, is on these theory-practice inconsistencies and their explanation in terms of the nature and acquisition of nursing practice scripts. The implications of nursing scripts for the promotion of critical thinking and evidence-based practice are discussed.

A comparison of teaching strategies for integrating information technology into clinical nursing education

As health care becomes more information-intensive and diverse, there is a need to integrate information technology (IT) into clinical education. Little is known, however, about how to design instructional strategies for integrating information technology into clinical nursing education. This article outlines the instructional strategies used by faculty in five nursing programs who taught students to use a point-of-care information technology system. The article also reports students' computer acceptance and summarizes IT clinical teaching recommendations.

HLA B*5701 is highly associated with restriction of virus replication in a subgroup of HIV-infected long term nonprogressors

A unique cohort of HIV-1-infected long term nonprogressors (LTNP) with normal CD4(+) T cell counts and <50 copies/ml of plasma were prospectively recruited for study. HLA typing revealed a dramatic association between the HLA B*5701 class I allele and nonprogressive infection [85% (11 of 13) vs. 9.5% (19 of 200) in progressors; P < 0. 001]. Antigen-specific CD8(+) T cells were enumerated by flow cytometric detection of intracellular IFN-gamma in response to HIV antigens and HLA B*57-gag tetramer staining. No quantitative differences in the total HIV-specific CD8(+) T cell responses were observed between B*57(+) LTNP and five B*57(+) progressors (P = 0.4). Although similar frequencies of peptide specific CD8(+) T cells were also found, the gag-specific CD8(+) T cell response in the LTNP group was highly focused on peptides previously shown to be B*57-restricted. These findings indicate that, within this phenotypically and genotypically distinct cohort, a host immune factor is highly associated with restriction of virus replication and nonprogressive disease. They also strongly suggest a mechanism of virus specific immunity that directly operates through the B*5701 molecule. Further characterization of qualitative differences in the virus-specific responses that distinguish HLA B*57(+) LTNP from progressors may ultimately define mechanisms of effective immune mediated restriction of virus replication.

Evaluating the role of physical and radiographic examinations in assessing bullet tract termination for gunshot victims

Knowledge of the path of a bullet and how it terminates is critical for expeditious assessment and optimal management of patients with gunshot wounds. To assess the accuracy of physical examination and X-rays in these patients, a prospective study was undertaken for all gunshot victims seen for a 1-year period on a single trauma service. The paramedics and trauma surgeons' physical examinations were evaluated for whether a bullet tract could be accurately categorized as 1) through and through, 2) graze, 3) palpable under dermis, or 4) retained (ie, not palpable). The impact of X-rays was assessed with regard to how it affected the trauma surgeons' categorization. A total of 78 patients were seen with a total of 120 bullet tracts. Seventy-seven per cent were injured by assault, and 64 per cent were shot with a 9-mm or .38-caliber handgun. Twenty of 60 (33%) bullet tracts on the torso terminated with a missile that was palpable under dermis, but only 2 of 10 neck (20%), 1 of 28 extremity (4%), and 1 of 22 head/face (5%) did so. Paramedics evaluated 15 torso bullet tracts that ended palpable under dermis, of which they detected 5 (33%). Upon initial examination, the trauma surgeon detected 11 of 20 torso bullet tracts that ended palpable under dermis (55%), and detected 14 of the 20 after X-rays were done (70%). Overall, obtaining X-rays changed the categorization for 15 of 111 bullet tracts (13%). We conclude that bullet tracts on the torso result in a subcutaneously palpable bullet one-third of the time, much more frequently than in other body regions. Paramedics only detect one-third of subcutaneously palpable missiles on the torso. X-rays change the categorization of bullet tracts infrequently. We recommend that a careful examination of the skin of the torso to detect palpable missiles be incorporated into the secondary survey of patients with wounds to that body region.

A two-year, double-blind comparison of estrogen-androgen and conjugated estrogens in surgically menopausal women. Effects on bone mineral density, symptoms and lipid profiles

OBJECTIVE

To compare the effects of two doses of conjugated equine estrogen (CEE) and two of esterified estrogen plus methyltestosterone (E + A) in surgically menopausal women.

STUDY DESIGN

A two-year, parallel-group, double-blind study of 311 women who were randomly assigned to one of four regimens: (1) CEE, 0.625 mg/d; (2) CEE, 1.25 mg/d; (3) esterified estrogens, 0.625 mg, + methyltestosterone, 1.25 mg/d; or (4) esterified estrogens, 1.25, + methyltestosterone, 2.5 mg/d. Study parameters were symptoms, lipids, bone mineral density, side effects and safety.

RESULTS

All treatments prevented loss of bone in the spine and hip. The higher E + A dose increased spine and hip BMD more than other treatments (P < .002). All treatments improved menopausal symptoms, with non-significantly greater improvements in well-being and sexual interest in the E + A groups. Similar and significant decreases in low-density lipoprotein were observed in all groups, but high-density lipoprotein and triglycerides were increased only in the unopposed estrogen groups (P < .05). Hirsutism was uncommon and similar in all groups at two years. Discontinuation rates and reasons for withdrawal from the study were similar in both groups. No clinically significant side effects or laboratory test abnormalities were seen.

CONCLUSION

As compared to estrogen alone, E + A significantly improved BMD and was well tolerated in surgically menopausal women.

The Canadian Study of Cardiac Transplantation. Atherosclerosis. Investigators of the CASCADE Study

OBJECTIVES

To describe risk factors associated with the development of transplantation coronary artery disease (TCAD).

DESIGN

A retrospective study of the Canadian experience.

PATIENTS

Seven hundred and nineteen patients with follow-up of at least 12 months following transplantation and a minimum of one coronary angiogram were analyzed.

RESULTS

Two hundred and fourteen patients (30%) developed angiographic evidence of TCAD during an average follow-up of 50+/-25 months. Actuarial freedom rate from TCAD averaged 60%, and survival averaged 85% five years following transplantation. Abnormal coronary angiograms increased from 11% to 40% between the first and the fifth year following transplantation. The Cox multivariate final model showed that recipients of donor hearts of 50 years and older (RR 4.35, 95% CI 2.32 to 8.15), patients with two or more episodes of acute rejection (RR 1.56, 95% CI 1.11 to 2.21) and patients with a diagnosis of ischemic cardiomyopathy before transplantation (RR 1.38, 95% CI 1.03 to 1.84) were at higher risk of TCAD. The same risk factors also had a significant effect on survival, although patients who were administered a hepatic hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor during follow-up had a higher survival rate (95% versus 85%, P=0.01) five years following heart transplantation.

CONCLUSIONS

Recipients of hearts from older donors, patients with an ischemic heart disease before transplantation and those with several episodes of acute rejection are at increased risk for TCAD. Patients who are administered an HMG-CoA reductase inhibitor during follow-up have a higher survival rate five years following transplantation.

A polymorphism in the regulatory region of the CC-chemokine receptor 5 gene influences perinatal transmission of human immunodeficiency virus type 1 to African-American infants

There are natural mutations in the coding and noncoding regions of the human immunodeficiency virus type 1 (HIV-1) CC-chemokine coreceptor 5 (CCR5) and in the related CCR2 protein (the CCR2-64I mutation). Individuals homozygous for the CCR5-Delta32 allele, which prevents CCR5 expression, strongly resist HIV-1 infection. Several genetic polymorphisms have been identified within the CCR5 5' regulatory region, some of which influence the rate of disease progression in adult AIDS study cohorts. We genotyped 1,442 infants (1,235 uninfected and 207 HIV-1 infected) for five CCR5 and CCR2 polymorphisms: CCR5-59353-T/C, CCR5-59356-C/T CCR5-59402-A/G, CCR5-Delta32, and CCR2-64I. The clinical significance of each genotype was assessed by measuring whether it influenced the rate of perinatal HIV-1 transmission among 667 AZT-untreated mother-infant pairs (554 uninfected and 113 HIV-1 infected). We found that the mutant CCR5-59356-T allele is relatively common in African-Americans (20.6% allele frequency among 552 infants) and rare in Caucasians and Hispanics (3.4 and 5.6% of 174 and 458 infants, respectively; P < 0.001). There were 38 infants homozygous for CCR5-59356-T, of whom 35 were African-Americans. Among the African-American infants in the AZT-untreated group, there was a highly significant increase in HIV-1 transmission to infants with two mutant CCR5-59356-T alleles (47.6% of 21), compared to those with no or one mutant allele (13.4 to 14.1% of 187 and 71, respectively; P < 0.001). The increased relative risk was 5.9 (95% confidence interval, 2.3 to 15.3; P < 0.001). The frequency of the CCR5-59356-T mutation varies between population groups in the United States, a low frequency occurring in Caucasians and a higher frequency occurring in African-Americans. Homozygosity for CCR5-59356-T is strongly associated with an increased rate of perinatal HIV-1 transmission.

Identification of a new recipient in the Sydney Blood Bank Cohort: a long-term HIV type 1-infected seroindeterminate individual

We have reported previously a cohort of long-term survivors of HIV-1 infection, known as the Sydney Blood Bank Cohort, who received HIV-1-positive blood from a common infected donor. A new recipient, C135, has been identified. This recipient became infected after receiving blood donated during the presumed time of seroconversion of the donor in February 1981. C135 has been infected for more than 18 years without signs of disease progression. The virus load in this recipient has remained below the detectable level (<20 RNA copies/ml of plasma) and repeated Western blot analyses have given an indeterminate result. By booster PCR techniques we have demonstrated that this individual is infected with HIV-1 and have characterized the viral nef and nef/LTR region sequences present. The strain of HIV-1 identified contains deletions of 88 bp from the nef alone region and a total of 139 bp deleted from the nef/LTR overlap and LTR regions. The LTR contains three wild-type Sp1 transcription factor-binding sites, the 3' wildtype NF-kappaB site, and a duplicated Sp1 and NF-kappaB region. A truncated Nef protein of only 19 amino acids is encoded. The deletions and rearrangements in the nef gene and LTR sequences are characteristic of Sydney Blood Bank Cohort strains of virus. The identification of C135 increases the Sydney Blood Bank Cohort size to nine individuals and represents a rare example of a genuine, long-term HIV-1 infection accompanied by indeterminate anti-HIV-1 serology.

The overactive bladder: neuropharmacological basis of clinical management

The overactive bladder continues to pose a major challenge to clinicians treating lower urinary tract disorders, not least because our understanding of the pathogenesis of detrusor overactivity is still relatively limited. However, progress in understanding the basis of the overactive bladder is moving steadily forward, accompanied by a growing number of different forms of treatment. New pharmacological treatments and variations in the mode of delivery of older agents offer hope of efficacy with fewer side-effects. Neuromodulation is also offering a viable alternative to surgery in patients unresponsive to medical treatment.

Rapid radiation events in the family Ursidae indicated by likelihood phylogenetic estimation from multiple fragments of mtDNA

The bear family (Ursidae) presents a number of phylogenetic ambiguities as the evolutionary relationships of the six youngest members (ursine bears) are largely unresolved. Recent mitochondrial DNA analyses have produced conflicting results with respect to the phylogeny of ursine bears. In an attempt to resolve these issues, we obtained 1916 nucleotides of mitochondrial DNA sequence data from six gene segments for all eight bear species and conducted maximum likelihood and maximum parsimony analyses on all fragments separately and combined. All six single-region gene trees gave different phylogenetic estimates; however, only for control region data was this significantly incongruent with the results from the combined data. The optimal phylogeny for the combined data set suggests that the giant panda is most basal followed by the spectacled bear. The sloth bear is the basal ursine bear, and there is weak support for a sister taxon relationship of the American and Asiatic black bears. The sun bear is sister taxon to the youngest clade containing brown bears and polar bears. Statistical analyses of alternate hypotheses revealed a lack of strong support for many of the relationships. We suggest that the difficulties surrounding the resolution of the evolutionary relationships of the Ursidae are linked to the existence of sequential rapid radiation events in bear evolution. Thus, unresolved branching orders during these time periods may represent an accurate representation of the evolutionary history of bear species.

In rats, odor-induced Fos in the olfactory pathways depends on the phase of the circadian clock

We used immunostaining for Fos to study the effect of circadian clock phase on odor-induced neuronal activation in the olfactory system in rats. Brief presentation of cedar odor to rats housed in constant darkness stimulated Fos expression in the main olfactory bulb, anterior olfactory nucleus, piriform cortex, and several other odor-responsive structures, both in the subjective day and subjective night phases of the cycle. Fos expression in response to odor, but not basal expression, was greatly enhanced in the subjective night in all structures examined. These findings are consistent with the idea that odor-induced neuronal activation in the olfactory pathways is modulated by the phase of the circadian clock.

Evaluation of consumer drug information databases

OBJECTIVES

To evaluate prescription drug information contained in six consumer drug information databases available on CD-ROM, and to make health care professionals aware of the information provided, so that they may appropriately recommend these databases for use by their patients.

DESIGN

Observational study of six consumer drug information databases: The Corner Drug Store, Home Medical Advisor, Mayo Clinic Family Pharmacist, Medical Drug Reference, Mosby's Medical Encyclopedia, and PharmAssist.

SETTING

Not applicable.

PATIENTS OR OTHER PARTICIPANTS

Not applicable.

INTERVENTIONS

Information on 20 frequently prescribed drugs was evaluated in each database. The databases were ranked using a point-scale system based on primary and secondary assessment criteria.

MAIN OUTCOME MEASURES

For the primary assessment, 20 categories of information based on those included in the 1998 edition of the USP DI Volume II, Advice for the Patient: Drug Information in Lay Language were evaluated for each of the 20 drugs, and each database could earn up to 400 points (for example, 1 point was awarded if the database mentioned a drug's mechanism of action). For the secondary assessment, the inclusion of 8 additional features that could enhance the utility of the databases was evaluated (for example, 1 point was awarded if the database contained a picture of the drug), and each database could earn up to 8 points.

RESULTS

The results of the primary and secondary assessments, listed in order of highest to lowest number of points earned, are as follows: Primary assessment--Mayo Clinic Family Pharmacist (379), Medical Drug Reference (251), PharmAssist (176), Home Medical Advisor (113.5), The Corner Drug Store (98), and Mosby's Medical Encyclopedia (18.5); secondary assessment--The Mayo Clinic Family Pharmacist (8), The Corner Drug Store (5), Mosby's Medical Encyclopedia (5), Home Medical Advisor (4), Medical Drug Reference (4), and PharmAssist (3).

CONCLUSION

The Mayo Clinic Family Pharmacist was the most accurate and complete source of prescription drug information based on the USP DI Volume II and would be an appropriate database for health care professionals to recommend to patients.

Cytokine production in rhesus monkeys infected with Plasmodium coatneyi

Plasmodium coatneyi infection in rhesus monkeys has been used as a model for studying human malaria. Cytokine production in this model, however, has so far not been examined. In this study, four rhesus monkeys were infected with P. coatneyi, with another four animals serving as uninfected controls. Blood samples were taken for the determination of daily parasitemia, and cytokine and prostaglandin E2 (PGE2) levels at days 0, 3, 5, 7, and 10. All inoculated animals became infected, with synchronized appearance of ring-stage parasites. Infected monkeys had increased plasma levels of proinflammatory cytokines (interleukin-1beta, interferon-gamma, and tumor necrosis factor-alpha) during the late stage of the infection. They also had increased production of ciliary neurotrophic factor. In conjunction with the production of proinflammatory cytokines, infected monkeys also had gradual increases in the production of PGE2. A continued definition of the P. coatneyi/rhesus monkey animal model should be useful for the elucidation of the immunopathogenesis of human malaria.

Vitamin A deficiency phrynoderma: due to malabsorption and inadequate diet

We describe a patient with vitamin A deficiency phrynoderma caused by a combination of inadequate dietary intake of vitamin A and beta-carotene and malabsorption secondary to primary visceral myopathy and total colectomy.

Spinal cord injury research: review and synthesis

This article provides a substantive review and synthesis of major areas of emphasis in spinal cord injury (SCI) research. Comprehensive examination of the current status and future implications for SCI research includes consideration of investigations from the following arenas: epidemiology, functional classification and prediction, neurophysiologic testing, models of injury and recovery, psychosocial considerations, surgical strategies, animal laboratory research, economic implications, life expectancy, complication rates, gender differences, pharmacological management, and prevention. Synthesis of these research conclusions from a broad spectrum of laboratory, clinical, and scientific domains provides opportunity for improving SCI prevention, treatment, and adaptation.