Nickel in ambient particulate matter and respiratory or cardiovascular outcomes: A critical review

Exposure to ambient particulate matter (PM) has been associated with respiratory and cardiovascular outcomes, and nickel has been more frequently associated with these outcomes than other metal constituents of ambient PM. Because of this, we evaluated whether the evidence to date supports causal relationships between exposure to nickel in ambient PM and respiratory or cardiovascular outcomes. We critically reviewed 38 studies in human populations published between 2012 and 2022. Although a large variety of respiratory and cardiovascular outcomes were examined, data were sparse for many. As a result, we focused our evaluation on seven respiratory outcomes and three cardiovascular outcomes that were each examined in ≥3 studies. Of these health outcomes, exposure to nickel in ambient PM has been statistically significantly associated with respiratory mortality, respiratory emergency hospital visits, asthma, lung function (i.e., forced expiratory volume in 1 s, forced vital capacity), cardiovascular mortality, and ischemic heart disease mortality. Studies of the health outcomes of focus are subject to multiple methodological limitations, primarily ecological fallacy (short-term exposure studies), exposure measurement error, confounding, model misspecification, and multiple comparisons issue. While some statistically significant associations were reported, they were not strong, precise, or consistent. Statistically significant findings for long-term exposure to nickel in PM were largely reported in studies that could not establish temporality, despite their cohort study design. Statistically significant findings for short-term exposure to nickel in PM were largely reported in studies that could establish temporality, although this cannot inform causal inference at the individual level due to the aggregate level data used. The biological plausibility of the associations is only supported at high concentrations not relevant to ambient exposures. Overall, the literature to date does not provide adequate support for a causal relationship between nickel in ambient PM and respiratory or cardiovascular outcomes.

Considerations towards the better integration of epidemiology into quantitative risk assessment

Environmental epidemiology has proven critical to study various associations between environmental exposures and adverse human health effects. However, there is a perception that it often does not sufficiently inform quantitative risk assessment. To help address this concern, in 2017, the Health and Environmental Sciences Institute initiated a project engaging the epidemiology, exposure science, and risk assessment communities with tripartite representation from government agencies, industry, and academia, in a dialogue on the use of environmental epidemiology for quantitative risk assessment and public health decision making. As part of this project, four meetings attended by experts in epidemiology, exposure science, toxicology, statistics, and risk assessment, as well as one additional meeting engaging funding agencies, were organized to explore incentives and barriers to realizing the full potential of epidemiological data in quantitative risk assessment. A set of questions was shared with workshop participants prior to the meetings, and two case studies were used to support the discussion. Five key ideas emerged from these meetings as areas of desired improvement to ensure that human data can more consistently become an integral part of quantitative risk assessment: 1) reducing confirmation and publication bias, 2) increasing communication with funding agencies to raise awareness of research needs, 3) developing alternative funding channels targeted to support quantitative risk assessment, 4) making data available for reuse and analysis, and 5) developing cross-disciplinary and cross-sectoral interactions, collaborations, and training. We explored and integrated these themes into a roadmap illustrating the need for a multi-stakeholder effort to ensure that epidemiological data can fully contribute to the quantitative evaluation of human health risks, and to build confidence in a reliable decision-making process that leverages the totality of scientific evidence.

Research on COVID-19 and air pollution: A path towards advancing exposure science

The COVID-19 pandemic has resulted in an extraordinary incidence of morbidity and mortality, with almost 6 million deaths worldwide at the time of this writing (https://covid19.who.int/). There has been a pressing need for research that would shed light on factors - especially modifiable factors - that could reduce risks to human health. At least several hundred studies addressing the complex relationships among transmission of SARS-CoV-2, air pollution, and human health have been published. However, these investigations are limited by available and consistent data. The project goal was to seek input into opportunities to improve and fund exposure research on the confluence of air pollution and infectious agents such as SARS-CoV-2. Thirty-two scientists with expertise in exposure science, epidemiology, risk assessment, infectious diseases, and/or air pollution responded to the outreach for information. Most of the respondents expressed value in developing a set of common definitions regarding the extent and type of public health lockdown. Traffic and smoking ranked high as important sources of air pollution warranting source-specific research (in contrast with assessing overall ambient level exposures). Numerous important socioeconomic factors were also identified. Participants offered a wide array of inputs on what they considered to be essential studies to improve our understanding of exposures. These ranged from detailed mechanistic studies to improved air quality monitoring studies and prospective cohort studies. Overall, many respondents indicated that these issues require more research and better study design. As an exercise to solicit opinions, important concepts were brought forth that provide opportunities for scientific collaboration and for consideration for funding prioritization. Further conversations on these concepts are needed to advance our thinking on how to design research that moves us past the documented limitations in the current body of research and prepares us for the next pandemic.

Curating the Evidence About COVID-19 for Frontline Public Health and Clinical Care: The Novel Coronavirus Research Compendium

The public health crisis created by the COVID-19 pandemic has spurred a deluge of scientific research aimed at informing the public health and medical response to the pandemic. However, early in the pandemic, those working in frontline public health and clinical care had insufficient time to parse the rapidly evolving evidence and use it for decision-making. Academics in public health and medicine were well-placed to translate the evidence for use by frontline clinicians and public health practitioners. The Novel Coronavirus Research Compendium (NCRC), a group of >60 faculty and trainees across the United States, formed in March 2020 with the goal to quickly triage and review the large volume of preprints and peer-reviewed publications on SARS-CoV-2 and COVID-19 and summarize the most important, novel evidence to inform pandemic response. From April 6 through December 31, 2020, NCRC teams screened 54 192 peer-reviewed articles and preprints, of which 527 were selected for review and uploaded to the NCRC website for public consumption. Most articles were peer-reviewed publications (n = 395, 75.0%), published in 102 journals; 25.1% (n = 132) of articles reviewed were preprints. The NCRC is a successful model of how academics translate scientific knowledge for practitioners and help build capacity for this work among students. This approach could be used for health problems beyond COVID-19, but the effort is resource intensive and may not be sustainable in the long term.

Trends in heroin use and injection drug use among high school students in five urban school districts in the US (2005-2017)

Background. We describe the prevalence of and changes in heroin use and injection drug use (IDU) among high school students in five large, urban school districts in the US (2005-2017); nearly three-fourths of the students were Black and/or Hispanic/Latino.Methods. Data are from the Centers for Disease Control and Prevention's "Youth Risk Behavior Survey" program, which includes biennial surveys in urban school districts. We pooled data across districts and survey years, and then generated weighted prevalence estimates (and 95% CIs) for any lifetime heroin use and IDU. Joinpoint regression modeling was used to estimate changes in prevalence over the study period.Results. Biennial prevalence estimates (2005-2017) for heroin use and IDU were above 1.8% for all seven timepoints. In 2017, prevalence of heroin use and IDU were 2.9% and 2.5%, respectively. Both heroin use and IDU were higher among boys than girls. There were statistically significant increases in heroin use and IDU among girls from 2005-2009, whereas changes over time were stable among boys.Conclusions. High school students in large, urban school districts may have higher rates of heroin use and IDU than US high school students in general, and there is little evidence of increases since 2009. This study suggests that adolescence may be a critical period for initiation of heroin use among adolescents in large urban school districts, the majority of whom are Black and/or Latino.Supplemental data for this article is available online at https://doi.org/10.1080/15332640.2021.1992327 .

Curating and translating the evidence about SARS-CoV-2 and COVID-19 for frontline public health and clinical care: The Novel Coronavirus Research Compendium (NCRC)

The public health crisis created by the SARS-CoV-2 pandemic has spurred a deluge of scientific research aimed at informing public health and medical response to the COVID-19 pandemic. However, those working in frontline public health and clinical care had insufficient time to parse the rapidly evolving evidence and use it for decision making. Academics in public health and medicine were well-placed to translate the evidence for use by frontline clinicians and public health practitioners. The Novel Coronavirus Research Compendium (NCRC), a group of >50 faculty and trainees, began in March 2020 with the goal to quickly triage and review the large volume of preprints and peer-reviewed publications on SARS-CoV-2 and COVID-19, and to summarize the most important, novel evidence to inform pandemic response. From April 6, 2020 through January 1, 2021, 54,192 papers and preprints were screened by NCRC teams and 527 were selected for review and uploaded to the NCRC website for public consumption. The majority of papers reviewed were peer-reviewed publications (n=395, 75%), published in 102 journals; 25% (n=132) of papers reviewed were of preprints. The NCRC is a successful model of how academics can support practitioners by translating scientific knowledge into action and help to build capacity among students for this work. This approach could be used for health problems beyond COVID-19, but the effort is resource intensive and may not be sustainable over the long term.

Comparative performance of five commercially available serologic assays to detect antibodies to SARS-CoV-2 and identify individuals with high neutralizing titers

Accurate serological assays to detect antibodies to SARS-CoV-2 are needed to characterize the epidemiology of SARS-CoV-2 infection and identify potential candidates for COVID-19 convalescent plasma (CCP) donation. This study compared the performance of commercial enzyme immunoassays (EIAs) to detect IgG or total antibodies to SARS-CoV-2 and neutralizing antibodies (nAb). The diagnostic accuracy of five commercially available EIAs (Abbott, Euroimmun, EDI, ImmunoDiagnostics, and Roche) to detect IgG or total antibodies to SARS-CoV-2 was evaluated from cross-sectional samples of potential CCP donors that had prior molecular confirmation of SARS-CoV-2 infection for sensitivity (n=214) and pre-pandemic emergency department patients for specificity (n=1,102). Of the 214 potential CCP donors, all were sampled >14 days since symptom onset and only a minority had been hospitalized due to COVID-19 (n=16 [7.5%]); 140 potential CCP donors were tested by all five EIAs and a microneutralization assay. When performed according to the manufacturers' protocol to detect IgG or total antibodies to SARS-CoV-2, the sensitivity of each EIA ranged from 76.4% to 93.9%, and the specificity of each EIA ranged from 87.0% to 99.6%. Using a nAb titer cutoff of ≥160 as the reference positive test (n=140 CCP donors), the empirical area under receiver operating curve of each EIA ranged from 0.66 (Roche) to 0.90 (Euroimmun). Commercial EIAs with high diagnostic accuracy to detect SARS-CoV-2 antibodies did not necessarily have high diagnostic accuracy to detect high nAbs. Some but not all commercial EIAs may be useful in the identification of individuals with high nAbs in convalescent individuals.

Variation in False-Negative Rate of Reverse Transcriptase Polymerase Chain Reaction-Based SARS-CoV-2 Tests by Time Since Exposure

BACKGROUND

Tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) based on reverse transcriptase polymerase chain reaction (RT-PCR) are being used to rule out infection among high-risk persons, such as exposed inpatients and health care workers. It is critical to understand how the predictive value of the test varies with time from exposure and symptom onset to avoid being falsely reassured by negative test results.

OBJECTIVE

To estimate the false-negative rate by day since infection.

DESIGN

Literature review and pooled analysis.

SETTING

7 previously published studies providing data on RT-PCR performance by time since symptom onset or SARS-CoV-2 exposure using samples from the upper respiratory tract (n = 1330).

PATIENTS

A mix of inpatients and outpatients with SARS-CoV-2 infection.

MEASUREMENTS

A Bayesian hierarchical model was fitted to estimate the false-negative rate by day since exposure and symptom onset.

RESULTS

Over the 4 days of infection before the typical time of symptom onset (day 5), the probability of a false-negative result in an infected person decreases from 100% (95% CI, 100% to 100%) on day 1 to 67% (CI, 27% to 94%) on day 4. On the day of symptom onset, the median false-negative rate was 38% (CI, 18% to 65%). This decreased to 20% (CI, 12% to 30%) on day 8 (3 days after symptom onset) then began to increase again, from 21% (CI, 13% to 31%) on day 9 to 66% (CI, 54% to 77%) on day 21.

LIMITATION

Imprecise estimates due to heterogeneity in the design of studies on which results were based.

CONCLUSION

Care must be taken in interpreting RT-PCR tests for SARS-CoV-2 infection-particularly early in the course of infection-when using these results as a basis for removing precautions intended to prevent onward transmission. If clinical suspicion is high, infection should not be ruled out on the basis of RT-PCR alone, and the clinical and epidemiologic situation should be carefully considered.

PRIMARY FUNDING SOURCE

National Institute of Allergy and Infectious Diseases, Johns Hopkins Health System, and U.S. Centers for Disease Control and Prevention.

Antibody avidity-based approach to estimate population-level incidence of hepatitis C

BACKGROUND & AIMS

Accurate HCV incidence estimates are critical for monitoring progress towards HCV elimination goals, including an 80% reduction in HCV incidence by 2030. Moreover, incidence estimates can help guide prevention and treatment programming, particularly in the context of the US opioid epidemic.

METHODS

An inexpensive, Genedia-based HCV IgG antibody avidity assay was evaluated as a platform to estimate cross-sectional, population-level primary HCV incidence using 1,840 HCV antibody and RNA-positive samples from 875 individuals enrolled in 5 cohort studies in the US and India. Using samples collected <2 years following HCV seroconversion, the mean duration of recent infection (MDRI) was calculated by fitting a maximum likelihood binomial regression model to the probability of appearing recent. Among samples collected ≥2 years post-HCV seroconversion, an individual-level false recent ratio (FRR) was calculated by estimating the probability of appearing recent using an exact binomial test. Factors associated with falsely appearing recent among samples collected ≥2 years post seroconversion were determined by Poisson regression with generalized estimating equations and robust variance estimators.

RESULTS

An avidity index cut-off of <40% resulted in an MDRI of 113 days (95% CI 84-146), and FRRs of 0.4% (95% CI 0.0-1.2), 4.6% (95% CI 2.2-8.3), and 9.5% (95% CI 3.6-19.6) among individuals who were HIV-uninfected, HIV-infected, and HIV-infected with a CD4 count <200/μl, respectively. No variation was seen between HCV genotypes 1 and 3. In hypothetical scenarios of high-risk settings, a sample size of <1,000 individuals could reliably estimate primary HCV incidence.

CONCLUSIONS

This cross-sectional approach can estimate primary HCV incidence for the most common genotypes. This tool can serve as a valuable resource for program and policy planners seeking to monitor and reduce HCV burden.

LAY SUMMARY

Determining the rate of new hepatitis C virus (HCV) infections in a population is critical to monitoring progress toward HCV elimination and to appropriately guide control efforts. However, since HCV infections are most often initially asymptomatic, it is difficult to estimate the rate of new HCV infections without following HCV-uninfected people over time and repeatedly testing them for HCV infection. Here, we present a novel, resource-efficient method to estimate the rate of new HCV infections in a population using data from a single timepoint.

Prevalence of Hepatitis B and Hepatitis D Virus Infections in the United States, 2011-2016

Among adults in the 2011-2016 National Health and Nutrition Examination Survey (NHANES), the estimated prevalence of hepatitis B surface antigen (HBsAg) was 0.36% overall and 3.4% in non-Hispanic Asians. Among adult HBsAg carriers, 42% had antibodies to hepatitis delta virus (anti-HDV). Routine anti-HDV testing should be considered for HBsAg carriers.

Adolescent Anabolic-Androgenic Steroid Use in Association with Other Drug Use, Injection Drug Use, and Team Sport Participation

Introduction

The majority of epidemiologic research on adolescent non-medical anabolic-androgenic steroid (AAS) use was conducted in the 1990s and early 2000s, indicating a need to update evidence for the modern era. We aim to understand the prevalence of AAS use among US adolescents and assess associations between AAS use, sports participation, other drug use, and injection drug use (IDU).

Methods

Using data from the 2017 National Youth Risk Behavior Survey, we estimated the prevalence of AAS use and tested for associations between AAS use, sports participation, and drug use, overall and by sex.

Results

The prevalence of AAS use was 2.98%. The prevalence among boys (3.46%) was higher than among girls (2.41%). AAS use was high among youth with lifetime heroin use (64.41%) and IDU (64.42%). There was no association between AAS and team sport participation (p=0.61).

Conclusions

Our results indicate that adolescent AAS use is an aspect of polysubstance use rather than a substance used solely for performance enhancement in sports. Research with adolescents should be mindful of the overlap of heroin and AAS use among youth with IDU.

Diversity of hepatitis C virus infection among HIV-infected people who inject drugs in India

The availability of generic direct acting antivirals (DAAs) for hepatitis C virus (HCV) treatment has prompted many low-and-middle-income countries to launch HCV elimination programs. Because the efficacy of some of these generic DAAs varies by HCV viral subtype, information on subtype distribution can contribute important information to these elimination programs. We conducted a cross-sectional serosurvey to characterize HCV subtype diversity among HIV positive people who inject drugs (PWID) across 14 cities in India. Of 801 HIV positive PWID sampled, 639 tested HCV antibody positive (78.9%). Among 105 samples sequenced, genotype 3 (58.1%) was the most commonly observed followed by genotype 1 (36.2%) and genotype 6 (5.7%). Of the genotype 3 infections, 65% were subtype 3a and 35% were subtype 3b. Of the genotype 1 infections, 94% were subtype 1a and 6% were subtype 1b. All genotype 6 samples were subtype 6n. There was some variability in genotype diversity depending on geographic region and PWID epidemic stage with greater diversity observed in older PWID epidemics. One sequence, HY018, did not cluster with any known reference sequences in phylogenetic analysis. Nearly 80% of HIV infected PWID across India are co-infected with HCV, and subtype prevalence and genetic diversity varied by region and PWID epidemic stage. HCV elimination programs in India will need to consider HCV subtype.

Hepatitis E Virus Seroprevalence and Correlates of Anti-HEV IgG Antibodies in the Rakai District, Uganda

A cross-sectional study was conducted of 500 human immunodeficiency virus (HIV)-infected adults frequency matched on age, sex, and community to 500 HIV-uninfected individuals in the Rakai District, Uganda to evaluate seroprevalence of anti-hepatitis E virus (HEV) IgG antibodies. HEV seroprevalence was 47%, and 1 HIV-infected individual was actively infected with a genotype 3 virus. Using modified Poisson regression, male sex (prevalence ratios [PR] = 1.247; 95% confidence interval [CI], 1.071-1.450) and chronic hepatitis B virus infection (PR = 1.377; 95% CI, 1.090-1.738) were associated with HEV seroprevalence. HIV infection status (PR = 0.973; 95% CI, 0.852-1.111) was not associated with HEV seroprevalence. These data suggest there is a large burden of prior exposure to HEV in rural Uganda.

Limited Coverage of Hepatitis C Virus Testing in the United States, 2013-2017

In the US household population, hepatitis C virus testing coverage marginally increased between 2013 and 2017 among persons born between 1966 and 1994 (13.2% to 16.8%) and persons born between 1945 and 1965 (12.3% to 17.3%). Testing coverage remains limited and sociodemographic disparities were observed in both populations.

Chronic Eosinophilic Dermatitis Associated with Persistent Feline Herpes Virus Infection in Cheetahs (Acinonyx jubatus)

A chronic ulcerative and eosinophilic dermatitis occurred in 20 captive cheetahs ( Acinonyx jubatus) with persistent feline herpes virus 1 (FHV1) infection. Affected animals had erythematous, ulcerated plaques primarily on the face and forelegs in sites of contact with lachrymal and salivary secretions. The dermatitis was characterized by dense infiltrates of eosinophils and plasma cells and pseudoepitheliomatous hyperplasia. Rare keratinocytes within the lesions had nuclei with marginated chromatin and small eosinophilic inclusions composed of herpes virus nucleocapsids. Virus isolated from lesions was confirmed to be FHV1. Lesions persisted and progressed unless removed by cryoexcision. The occurrence of this unusual reaction to FHV1 in approximately 5% of captive North American cheetahs suggests a species propensity for a Th2-dominant response to herpes virus infection. This atypical immune reaction may indicate a heritable trait or modulation of the immune response by other factors such as chronic stress.

Use of Hepatitis C Virus (HCV) Immunoglobulin G Antibody Avidity as a Biomarker to Estimate the Population-Level Incidence of HCV Infection

BACKGROUND

Sensitive methods are needed to estimate the population-level incidence of hepatitis C virus (HCV) infection.

METHODS

We developed an HCV immunoglobulin G (IgG) antibody avidity assay by modifying the Ortho 3.0 HCV enzyme-linked immunoassay and tested 997 serum or plasma samples from 568 people who inject drugs enrolled in prospective cohort studies. Avidity-based testing algorithms were evaluated by their (1) mean duration of recent infection (MDRI), defined as the average time an individual is identified as having been recently infected, according to a given algorithm; (2) false-recent rate, defined as the proportion of samples collected >2 years after HCV seroconversion that were misclassified as recent; (3) sample sizes needed to estimate incidence; and (4) power to detect a reduction in incidence between serial cross-sectional surveys.

RESULTS

A multiassay algorithm (defined as an avidity index of <30%, followed by HCV viremia detection) had an MDRI of 147 days (95% confidence interval [CI], 125-195 days), and the false-recent rates were 0.7% (95% CI, .2%-1.8%) and 7.6% (95% CI, 4.2%-12.3%) among human immunodeficiency virus (HIV)-negative and HIV-positive persons, respectively. In various simulated high-risk populations, this algorithm required <1000 individuals to estimate incidence (relative standard error, 30%) and had >80% power to detect a 50% reduction in incidence.

CONCLUSIONS

Avidity-based algorithms have the capacity to accurately estimate HCV infection incidence and rapidly assess the impact of public health efforts among high-risk populations. Efforts to optimize this method should be prioritized.

Human papillomavirus detection and comorbidity: critical issues in selection of patients with oropharyngeal cancer for treatment De-escalation trials

BACKGROUND

The presence of human papillomavirus (HPV)-infection in oropharyngeal squamous cell carcinoma (OPSCC) is a major determinant in prognostic risk modeling. However, most risk models are based on clinical trials which only include a selected patient population. The clinical significance of HPV and other prognostic factors in patients with OPSCC remains to be evaluated in a large, unselected cohort, which also includes patients with stage I/II disease and patients with severe comorbidity.

PATIENTS AND METHODS

All patients diagnosed with OPSCC in 2000-2006 in two Dutch university hospitals were included. The presence of an oncogenic HPV infection was determined by p16-immunostaining, followed by a high-risk HPV general primer 5+/6+ DNA PCR on the p16-positive cases. Cox regression analysis was carried out to compare survival rates between HPV-positive and HPV-negative patients and a prognostic model was generated by recursive partitioning.

RESULTS

In total, 163 of 841 (19.4%) tumors were HPV-positive. Patients with HPV-positive OPSCC had a more favorable overall survival [73.5% versus 40.9% after 5 years; P < 0.001; hazard ratio = 0.34, 95% confidence interval (CI) 0.25-0.48] compared with patients with HPV-negative OPSCC. Patients with p16-positive but HPV DNA-negative tumors showed a significantly less favorable survival than patients with p16-positive and HPV DNA-positive tumors (P < 0.001). A prognostic model was developed in which patients were classified into three risk groups according to HPV status, nodal stage and comorbidity. [Harrell's concordance index of 0.68 (95% CI 0.65-0.71)].

CONCLUSIONS

Tumor HPV status is a strong and independent prognostic factor for survival among patients with OPSCC. A prognostic risk model was proposed, based on our large, unselected cohort of patients with HPV status, comorbidity and nodal stage being the important prognostic factors. In addition, this study emphasizes the importance of performing an HPV DNA-specific test besides p16-immunostaining.

An evaluation of the GlideScope®, a new video laryngoscope for difficult airways

BACKGROUND AND OBJECTIVES

The GlideScope is a new video laryngoscope. The aim of our study was to assess its use compared to a Macintosh blade in airway scenarios on the Airman airway simulator. The scenarios were: 'normal' or resting state of the manikin, pharyngeal obstruction, cervical rigidity and tongue oedema.

METHODS

Thirty anaesthetists from the Christchurch Anaesthetic Department attempted to pass a bougie or stylet through the vocal cords of the manikin with a size 3 Macintosh blade, then the GlideScope. View at laryngoscopy, ease of 'intubation' and whether they thought the GlideScope would be useful in clinical practice were recorded.

RESULTS

Forty three percent (P = 0.02) found an improved view with the GlideScope in the pharyngeal obstruction scenario. In the other scenarios there was no significant difference in view. Reportage of ease of intubation showed no statistical difference in any scenarios. However, 93% of anaesthetists considered having the GlideScope would be useful if faced clinically with one or more of the studied scenarios.

CONCLUSIONS

The GlideScope improved the view in one of three difficult airway situations when used by anaesthetists with no formal training in its use. No single airway device offers a solution to all scenarios, however, we consider that the GlideScope is a useful addition to the range of difficult airway devices available.

Acute effects of peritoneal dialysis on hemodynamics

OBJECTIVES

To investigate the acute hemodynamic effects of peritoneal dialysis (PD) using the noninvasive Portapres technique [TNO Biomedical Instrumentation (TNO BMI); Amsterdam, The Netherlands].

DESIGN AND METHODS

Blood pressure was measured in 21 consecutive patients on continuous ambulatory PD during a standard peritoneal permeability analysis (SPA). Blood pressure, stroke volume, cardiac output, and total peripheral resistance were recorded and calculated using continuous finger pressure recordings with Portapres and Modelflow software (TNO BMI). The SPA consists of four phases: (1) drainage of night dwell dialysate, (2) instillation of a rinsing solution (1.36% glucose), (3) drainage of rinsing solution, and (4) instillation of the test solution (3.86% glucose to which dextran 70 has been added).

RESULTS

Both systolic blood pressure (SBP) (7 +/- 9 mmHg, p < 0.005) and diastolic blood pressure (DBP) (5 +/- 6 mmHg, p < 0.01) increased during phase 2. Systolic BP and DBP increased further during phase 4 (SBP 8 +/- 14 mmHg, p < 0.05; DBP 6 +/- 8 mmHg, p < 0.005). These BP increases were caused by a rise in total peripheral resistance of 10% +/- 18% (p< 0.05) during phase 1, and 15% +/- 21% (p < 0.005) during phase 2.

CONCLUSIONS

Instillation and dwell of a dialysis solution during PD causes a rise in blood pressure. This is caused by an increase in total peripheral resistance. Factors influencing total peripheral resistance could be a direct mechanical effect of dialysate on mesenteric resistance vessels or a temperature-related effect.

Pyrokinin neuropeptides in a crustacean. Isolation and identification in the white shrimp Penaeus vannamei

Identification of substances able to elicit physiological or behavioural processes that are related to reproduction would greatly contribute to the domestication of commercially important crustaceans that do not reproduce easily in captivity. Crustaceans are thought to release urine signals used for chemical communication involved in courtship behaviour. In contrast to insects, very little is known about the endocrinological processes underlying this phenomenon. Therefore, an extract of 3500 central nervous systems of female white shrimp Penaeus vannamei was screened for myotropic activity in order to purify pyrokinin-like peptides that belong to the pyrokinin/PBAN neuropeptide family. Members of this family regulate reproductive processes in insects, including pheromone biosynthesis. Purification of these pyrokinins was achieved by a combination of reversed-phase and normal-phase chromatography. Subsequent characterization by mass spectrometry, Edman degradation and peptide synthesis resulted in the elucidation of two novel peptides. Pev-PK 1 has the primary sequence DFAFSPRL-NH(2) and a second peptide (Pev-PK 2) is characterized as the nonapeptide ADFAFNPRL-NH(2). Pev-PK 1 contains the typical FXPRL-NH(2) (X = G, S, T or V) C-terminal sequence that characterizes members of the versatile pyrokinin/PBAN family. Pev-PK 2 displays an Asn residue at the variable X position of the core pyrokinin sequence. These crustacean pyrokinins are the first to be found in a noninsect. The synthetic peptides display myotropic activity on the Leucophaea maderae as well as on the Astacus leptodactylus hindgut.

Silent ischaemia and hypertension

For many years now, silent ischaemia has been recognized as a distinct clinical entity, and its relevance in different patient groups has been established. However, a number of basic questions have not been answered. In explaining the pathophysiology of silent ischaemia, factors affecting both the demand and the supply side are now being recognized. With the exception of certain well-defined groups, it is not clear why some patients are mostly symptomatic, while other patients are predominantly asymptomatic. There appear to be many factors influencing the ischaemic pain threshold. Studies investigating the prevalence of silent ischaemia show a remarkably high prevalence of silent ischaemia in different patient groups. Patients with hypertension but without coronary artery disease form a specific and vulnerable high-risk population that is particularly prone to silent ischaemia. Since changes at the macrovascular level are not responsible, various factors negatively influencing either cardiac supply or demand have been investigated. A reduced coronary reserve is central in explaining the increased prevalence of silent ischaemia in hypertensives. Left ventricular hypertrophy renders meaningful detection of ST segment changes difficult, but a possible solution dealing with this problem is offered by applying more stringent criteria in terms of minimal ST depression in the definition of ischaemia. The treatment of silent ischaemia is largely the same as for angina pectoris, but whether therapy should be directed at elimination of all ischaemic episodes or only of symptomatic episodes depends on further prospective work addressing this question.

The kinin peptide family in invertebrates

Kinins comprise a family of peptides that were first found in the central nervous system of insects and recently also in mollusks and crustaceans. After the isolation of the first members of the kinin family, the leukokinins from Leucophaea maderae, leukokinin-related peptides were found in the cricket Acheta domesticus and the locust Locusta migratoria, all through their ability to induce Leucophaea maderae hindgut contraction. Subsequently, kinins were found in the mosquitoes Culex salinarius and Aedes aegypti and in the earworm Helicoverpa zea. The first noninsect member of this family was isolated from a mollusk, the pond snail Lymnaea stagnalis. Most recently our group has isolated the first kinins from crustaceans. Six kinins were isolated from the white shrimp Penaeus vannamei. To date, 35 members of this family have been isolated. The first relatively small family of insect kinins has grown into an expanding and rather large family with members in insects, crustaceans, and mollusks. In this paper we discuss the kinin family in terms of method of isolation, structure, in vitro and in vivo activity, distribution, receptors, and signal transduction. We will compare the crustacean and insect members of the kinin family, using the data available on crustacea.

What should doctors wear in the accident and emergency department? Patients' perception

In many accident and emergency (A&E) departments doctors still wear white coats or their ordinary clothes, rather than a type of uniform, which, should it become contaminated, can be changed easily for a clean uniform. Before a change of clothing to a uniform could be considered in an inner-city A&E department, a study was carried out to assess the public's perception towards different styles of dress. Three hundred and twenty-nine questionnaires were returned by minor injury patients requiring a radiograph. The study was carried out over 3 weeks in January 1993. Each week a different style of dress was worn: week 1--white coats, week 2--normal clothing and week 3--theatre greens. The majority of patients thought that style of dress was important but did not alter their attitude towards the A&E medical staff. Therefore, there is no reason why doctors should not wear a more appropriate uniform that can be changed easily when contaminated.

A randomised double-blind study of interpleural analgesia after cholecystectomy

Continuous interpleural analgesia provided by 4 hourly injections of 20 ml bupivacaine 0.5% with adrenaline 5 micrograms/ml was compared with placebo in a randomised, double-blind study after cholecystectomy. All patients self-administered intravenous morphine using a patient-controlled analgesia device. There was a highly significant difference in mean morphine consumption between the groups (72 mg as compared with 22 mg). Visual analogue pain scores tended to be lower in the bupivacaine group throughout and this was significant at 2 hours. Respiratory function measurements were not significantly different between the groups. The mean peak venous plasma bupivacaine concentration after the sixth dose was 3.03 micrograms/ml and no symptoms suggestive of local anaesthetic toxicity occurred. It is concluded that this regimen can provide effective and continuous analgesia after cholecystectomy and that combined administration of interpleural bupivacaine and systemic morphine is more effective than morphine alone in the immediate postoperative period. The doses of bupivacaine required for optimal use of the technique lead to significant total plasma bupivacaine concentrations within 24 hours.

Structure-activity studies on narcotic antagonists. 2. N-substituted ethyl 3-(m- or p-hydroxyphenyl) nipecotates

A number of N-substituted ethyl 3-(n- or p-hydroxyphenyl)nipecotates were synthesized to evaluate the role of a m- or p-hydroxy substituted beta-phenethylamine moiety in narcotic antagonist action. Ethyl m- or p-methoxy-phenylcyanoacetate was alkylated with 1-bromo-3-chloropropane. The resultant chloronitriles were hydrogenated (Raney Ni) to amines and cyclized to yield the N-substituted ethyl 3-(m- or p-methoxyphenyl)nipecotates. These were N-benzylated, O-demethylated using BBr3, N-debenzylated, and then N-alkylated. The following N-substituted derivatives were prepared: methyl, allyl, cyclopropylmethyl, and n-propyl. No significant morphine-like analgesic activity was found in mice by the tail-flick method. The acetic writhing assay showed several compounds to possess analgesic activity. N-n-Propyl and N-(cyclopropylmethyl) m-hydroxy derivatives were marginally active antagonists by the mouse tail-flick method. Surprisingly, the N-methyl m-hydroxy derivative, 11m, was found to be an antagonist.