County-wide assessments of Illinois white-tailed deer (Odocoileus virginianus) prion protein gene variation using improved primers and potential implications for management

Chronic wasting disease (CWD) is a fatal, highly infectious prion disease that affects captive and wild cervids. Chronic wasting disease is the only known transmissible spongiform encephalopathy affecting free-ranging wildlife. In CWD-positive deer, some haplotypes of the prion protein gene PRNP are detected at lower frequencies as compared to CWD-negative deer, as are some variants of the prion protein PrP. Here, we examined wild, hunter-harvested CWD-negative white-tailed deer (Odocoileus virginianus) to determine whether there were geographical or temporal differences in the PRNP haplotypes, PRNP diplotypes, PrP proteoforms, and in the proportion of deer with at least one protective haplotype. We sampled 96-100 hunter-harvested deer per county at two time points in the Illinois counties of Jo Daviess, LaSalle, and Winnebago, chosen based on their geographic locations and known occurrence of CWD. The entire coding region of PRNP was sequenced, with haplotypes, diplotypes, and PrP proteoforms inferred. Across time, in Winnebago there was a significant increase in PrP proteoform F (p = 0.034), which is associated with a lower vulnerability to CWD. In every county, there was an increase over time in the frequency of deer carrying at least one protective haplotype to CWD, with a significant increase (p = 0.02) in the Jo Daviess County CWD infected region. We also found that primer combination was important as there was an 18.7% difference in the number of the deer identified as homozygous depending on primer usage. Current Illinois state management practices continue to remove CWD infected deer from locally infected areas helping to keep CWD prevalence low. Nonetheless, continued research on spatial and temporal changes in PRNP haplotypes, PrP proteoforms, and levels of deer vulnerability among Illinois deer will be important for the management of CWD within the state of Illinois and beyond.

Shedding and stability of CWD prion seeding activity in cervid feces

CWD is an emergent prion disease that now affects cervid species on three continents. CWD is efficiently spread in wild and captive populations, likely through both direct animal contact and environmental contamination. Here, by longitudinally assaying in feces of CWD-exposed white-tailed deer by RT-QuIC, we demonstrate fecal shedding of prion seeding activity months before onset of clinical symptoms and continuing throughout the disease course. We also examine the impact of simulated environmental conditions such as repeated freeze-thaw cycles and desiccation on fecal prion seeding activity. We found that while multiple (n = 7) freeze-thaw cycles substantially decreased fecal seeding activity, desiccation had little to no effect on seeding activity. Finally, we examined whether RT-QuIC testing of landscape fecal deposits could distinguish two premises with substantial known CWD prevalence from one in which no CWD-infected animals had been detected. In the above pilot study, this distinction was possible. We conclude that fecal shedding of CWD prions occurs over much of the disease course, that environmental factors influence prion seeding activity, and that it is feasible to detect fecal prion contamination using RT-QuIC.

Estimating relative CWD susceptibility and disease progression in farmed white-tailed deer with rare PRNP alleles

Chronic wasting disease is a prion disease affecting both free-ranging and farmed cervids in North America and Scandinavia. A range of cervid species have been found to be susceptible, each with variations in the gene for the normal prion protein, PRNP, reportedly influencing both disease susceptibility and progression in the respective hosts. Despite the finding of several different PRNP alleles in white-tailed deer, the majority of past research has focused on two of the more common alleles identified-the 96G and 96S alleles. In the present study, we evaluate both infection status and disease stage in nearly 2100 farmed deer depopulated in the United States and Canada, including 714 CWD-positive deer and correlate our findings with PRNP genotype, including the more rare 95H, 116G, and 226K alleles. We found significant differences in either likelihood of being found infected or disease stage (and in many cases both) at the time of depopulation in all genotypes present, relative to the most common 96GG genotype. Despite high prevalence in many of the herds examined, infection was not found in several of the reported genotypes. These findings suggest that additional research is necessary to more properly define the role that these genotypes may play in managing CWD in both farmed and free-ranging white-tailed deer, with consideration for factors including relative fitness levels, incubation periods, and the kinetics of shedding in animals with these rare genotypes.

Detection of CWD in cervids by RT-QuIC assay of third eyelids

The diagnosis of chronic wasting disease (CWD) relies on demonstration of the disease-associated misfolded CWD prion protein (PrP^CWD) in brain or retropharyngeal lymph node tissue by immunodetection methods, e.g. ELISA and immunohistochemistry (IHC). The success of these methods relies on a quality sample of tissues, which requires both anatomical knowledge and considerable dissection to collect. As the prevalence of CWD continues to increase globally, the development of fast and cost-effective methods to detect the disease is vital to facilitate CWD detection and surveillance. To address these issues, we have evaluated third eyelids from CWD-infected deer and elk using real-time quaking induced conversion (RT-QuIC). We identified prion seeding activity in third eyelids in 24 of 25 (96%) CWD-infected white-tailed deer (Odocoileus virginianus). We detected RT-QuIC positivity in the third eyelid as early as 1 month after experimental CWD exposure. In addition, we identified prion seeding activity in third eyelids of 18 of 25 (72%) naturally exposed asymptomatic CWD-positive rocky mountain elk (Cervus canadensis nelson). We compared CWD detection by RT-QuIC and IHC in third eyelid, retropharyngeal lymph node, and brain in 10 deer in early symptomatic stage of disease. IHC detected PrP^CWD deposition in third eyelid lymphoid follicles in 5 of 10 deer (50%) whereas third eyelids of all 10 animals were positive by RT-QuIC. This difference reflected in part a lower requirement for lymphoid follicle presence for seeding activity detection by RT-QuIC. In conclusion, RT-QuIC analysis of the third eyelid, an easily accessed tissue, has potential to advance CWD detection and testing compliance.

Design, implementation, and interpretation of amplification studies for prion detection

Amplification assays for transmissible spongiform encephalopathies have been in development for close to 15 years, with critical implications for the postmortem and antemortem diagnosis of human and animal prion diseases. Little has been published regarding the structured development, implementation and interpretation of experiments making use of protein misfolding cyclic amplification (PMCA) and real time quaking-induced conversion (RT-QuIC), and our goal with this Perspectives manuscript is to offer a framework which might allow for more efficient expansion of pilot studies into diagnostic trials in both human and animal subjects. This framework is made up of approaches common to diagnostic medicine, including a thorough understanding of analytical and diagnostic sensitivity and specificity, an a priori development of amplification strategy, and an effective experimental design. It is our hope that a structured framework for prion amplification assays will benefit not only experiments seeking to sensitively detect naturally-occurring cases of prion diseases and describe the pathogenesis of TSEs, but ultimately assist with future endeavors seeking to use these methods more broadly for other protein misfolding disorders, including Alzheimer's and Parkinson's disease.

Chronic wasting disease management in ranched elk using rectal biopsy testing

Chronic wasting disease (CWD) is a transmissible spongiform encephalopathy (TSE) affecting members of the cervid species, and is one of the few TSEs with an expanding geographic range. Diagnostic limitations, efficient transmission, and the movement of infected animals are important contributing factors in the ongoing spread of disease. Managing CWD in affected populations has proven difficult, relying on population reduction in the case of wild deer and elk, or quarantine and depopulation in farmed cervids. In the present study, we evaluated the effectiveness of managing endemic CWD in a closed elk herd using antemortem sampling combined with both conventional and experimental diagnostic testing, and selective, targeted culling of infected animals. We hypothesized that the real-time quaking-induced conversion (RT-QuIC) assay, a developing amplification assay, would offer greater detection capabilities over immunohistochemistry (IHC) in the identification of infected animals using recto-anal mucosa associated lymphoid tissue (RAMALT). We further sought to develop a better understanding of CWD epidemiology in elk with various PRNP alleles, and predicted that CWD prevalence would decrease with targeted culling. We found that RT-QuIC identified significantly more CWD-positive animals than IHC using RAMALT tissues (121 vs. 86, respectively, out of 553 unique animals), and that longstanding disease presence was associated with an increasing frequency of less susceptible PRNP alleles. Prevalence of CWD increased significantly over the first two years of the study, implying that refinements in our management strategy are necessary to reduce the prevalence of CWD in this herd.

Estimating chronic wasting disease susceptibility in cervids using real-time quaking-induced conversion

In mammals, susceptibility to prion infection is primarily modulated by the host's cellular prion protein (PrP^C) sequence. In the sheep scrapie model, a graded scale of susceptibility has been established both in vivo and in vitro based on PrP^C amino acids 136, 154 and 171, leading to global breeding programmes to reduce the prevalence of scrapie in sheep. Chronic wasting disease (CWD) resistance in cervids is often characterized as decreased prevalence and/or protracted disease progression in individuals with specific alleles; at present, no PrP^C allele conferring absolute resistance in cervids has been identified. To model the susceptibility of various naturally occurring and hypothetical cervid PrP^C alleles in vitro, we compared the amplification rates and amyloid extension efficiencies of eight distinct CWD isolates in recombinant cervid PrP^C substrates using real-time quaking-induced conversion. We hypothesized that the in vitro conversion characteristics of these isolates in cervid substrates would correlate to in vivo susceptibility - permitting susceptibility prediction for the rare alleles found in nature. We also predicted that hypothetical alleles with multiple resistance-associated codons would be more resistant to in vitro conversion than natural alleles with a single resistant codon. Our studies demonstrate that in vitro conversion metrics align with in vivo susceptibility, and that alleles with multiple amino acid substitutions, each influencing resistance independently, do not necessarily contribute additively to conversion resistance. Importantly, we found that the naturally occurring whitetail deer QGAK substrate exhibited the slowest amplification rate among those evaluated, suggesting that further investigation of this allele and its resistance in vivo is warranted.

Evolution of Diagnostic Tests for Chronic Wasting Disease, a Naturally Occurring Prion Disease of Cervids

Since chronic wasting disease (CWD) was first identified nearly 50 years ago in a captive mule deer herd in the Rocky Mountains of the United States, it has slowly spread across North America through the natural and anthropogenic movement of cervids and their carcasses. As the endemic areas have expanded, so has the need for rapid, sensitive, and cost effective diagnostic tests—especially those which take advantage of samples collected antemortem. Over the past two decades, strategies have evolved from the recognition of microscopic spongiform pathology and associated immunohistochemical staining of the misfolded prion protein to enzyme-linked immunoassays capable of detecting the abnormal prion conformer in postmortem samples. In a history that parallels the diagnosis of more conventional infectious agents, both qualitative and real-time amplification assays have recently been developed to detect minute quantities of misfolded prions in a range of biological and environmental samples. With these more sensitive and semi-quantitative approaches has come a greater understanding of the pathogenesis and epidemiology of this disease in the native host. Because the molecular pathogenesis of prion protein misfolding is broadly analogous to the misfolding of other pathogenic proteins, including Aβ and α-synuclein, efforts are currently underway to apply these in vitro amplification techniques towards the diagnosis of Alzheimer’s disease, Parkinson’s disease, and other proteinopathies. Chronic wasting disease—once a rare disease of Colorado mule deer—now represents one of the most prevalent prion diseases, and should serve as a model for the continued development and implementation of novel diagnostic strategies for protein misfolding disorders in the natural host.

Detection of chronic wasting disease prion seeding activity in deer and elk feces by real-time quaking-induced conversion

Chronic wasting disease (CWD) is an emergent prion disease affecting cervid species in North America, Canada, South Korea, and recently, Norway. Detection of CWD has been advanced by techniques that rely on amplification of low levels of prion amyloid to a detectable level. However, the increased sensitivity of amplification assays is often compromised by inhibitors and/or activators in complex biologic samples including body fluids, excreta, or the environment. Here, we adapt real-time quaking-induced conversion conditions to specifically detect CWD prions in fecal samples from both experimentally infected deer and naturally infected elk and estimate environmental contamination. The results have application to detection, surveillance and management of CWD, and potentially to other protein-misfolding diseases.

Use of a Multiplex Polymerase Chain Reaction to Rapidly Differentiate Neospora Caninum from Toxoplasma Gondii in an Adult Dog with Necrotizing Myocarditis and Myocardial Infarct

This report describes a 3-year-old male castrated Mastiff dog that died unexpectedly with locally extensive, acute, necrotizing myocarditis and myocardial infarction. Intralesional protozoal tachyzoites in the affected myocardium were confirmed to be Neospora caninum by a novel multiplex polymerase chain reaction (PCR) and immunohistochemistry. Protozoal organisms were not identified in other tissues by histology, immunohistochemistry, or PCR. The multiplex PCR assay was used to quickly provide preliminary results on fresh myocardium to differentiate N. caninum and Toxoplasma gondii. Neosporosis is an uncommon cause of myocarditis in adult dogs and differential diagnoses for myocarditis in this population of dogs are reviewed.

Limited amplification of chronic wasting disease prions in the peripheral tissues of intracerebrally inoculated cattle

Chronic wasting disease (CWD) is a fatal neurodegenerative disease, classified as a prion disease or transmissible spongiform encephalopathy (TSE) similar to bovine spongiform encephalopathy (BSE). Cervids affected by CWD accumulate an abnormal protease-resistant prion protein throughout the central nervous system (CNS), as well as in both lymphatic and excretory tissues - an aspect of prion disease pathogenesis not observed in cattle with BSE. Using seeded amplification through real-time quaking-induced conversion, we investigated whether the bovine host or prion agent was responsible for this aspect of TSE pathogenesis. We blindly examined numerous central and peripheral tissues from cattle inoculated with CWD for prion seeding activity. Seeded amplification was readily detected in the CNS, though rarely observed in peripheral tissues, with a limited distribution similar to that of BSE prions in cattle. This seems to indicate that prion peripheralization in cattle is a host-driven characteristic of TSE infection.

Quantitative assessment of prion infectivity in tissues and body fluids by real-time quaking-induced conversion

Prions are amyloid-forming proteins that cause transmissible spongiform encephalopathies through a process involving the templated conversion of the normal cellular prion protein (PrP(C)) to a pathogenic misfolded conformation. Templated conversion has been modelled in several in vitro assays, including serial protein misfolding amplification, amyloid seeding and real-time quaking-induced conversion (RT-QuIC). As RT-QuIC measures formation of amyloid fibrils in real-time, it can be used to estimate the rate of seeded conversion. Here, we used samples from deer infected with chronic wasting disease (CWD) in RT-QuIC to show that serial dilution of prion seed was linearly related to the rate of amyloid formation over a range of 10(-3) to 10(-8) µg. We then used an amyloid formation rate standard curve derived from a bioassayed reference sample (CWD+ brain homogenate) to estimate the prion seed concentration and infectivity in tissues, body fluids and excreta. Using these methods, we estimated that urine and saliva from CWD-infected deer both contained 1-5 LD50 per 10 ml. Thus, over the 1-2 year course of an infection, a substantial environmental reservoir of CWD prion contamination accumulates.

Chronic wasting disease of cervids: current knowledge and future perspectives

A naturally occurring transmissible spongiform encephalopathy (TSE) of mule deer was first reported in Colorado and Wyoming in 1967 and has since spread to other members of the cervid family in 22 states, 2 Canadian provinces, and the Republic of Korea. Chronic wasting disease (CWD), caused by exposure to an abnormally folded isoform of the cellular prion protein, is characterized by progressive neurological disease in susceptible natural and experimental hosts and is ultimately fatal. CWD is thought to be transmitted horizontally in excreta and through contaminated environments, features common to scrapie of sheep, though rare among TSEs. Evolving detection methods have revealed multiple strains of CWD and with continued development may lead to an effective antemortem test. Managing the spread of CWD, through the development of a vaccine or environmental cleanup strategies, is an active area of interest. As such, CWD represents a unique challenge in the study of prion diseases.

Prion-seeding activity in cerebrospinal fluid of deer with chronic wasting disease

Transmissible spongiform encephalopathies (TSEs), or prion diseases, are a uniformly fatal family of neurodegenerative diseases in mammals that includes chronic wasting disease (CWD) of cervids. The early and ante-mortem identification of TSE-infected individuals using conventional western blotting or immunohistochemistry (IHC) has proven difficult, as the levels of infectious prions in readily obtainable samples, including blood and bodily fluids, are typically beyond the limits of detection. The development of amplification-based seeding assays has been instrumental in the detection of low levels of infectious prions in clinical samples. In the present study, we evaluated the cerebrospinal fluid (CSF) of CWD-exposed (n=44) and naïve (n=4) deer (n=48 total) for CWD prions (PrP^d) using two amplification assays: serial protein misfolding cyclic amplification with polytetrafluoroethylene beads (sPMCAb) and real-time quaking induced conversion (RT-QuIC) employing a truncated Syrian hamster recombinant protein substrate. Samples were evaluated blindly in parallel with appropriate positive and negative controls. Results from amplification assays were compared to one another and to obex immunohistochemistry, and were correlated to available clinical histories including CWD inoculum source (e.g. saliva, blood), genotype, survival period, and duration of clinical signs. We found that both sPMCAb and RT-QuIC were capable of amplifying CWD prions from cervid CSF, and results correlated well with one another. Prion seeding activity in either assay was observed in approximately 50% of deer with PrP^d detected by IHC in the obex region of the brain. Important predictors of amplification included duration of clinical signs and time of first tonsil biopsy positive results, and ultimately the levels of PrP^d identified in the obex by IHC. Based on our findings, we expect that both sPMCAb and RT-QuIC may prove to be useful detection assays for the detection of prions in CSF.

Rapid antemortem detection of CWD prions in deer saliva

Chronic wasting disease (CWD) is an efficiently transmitted prion disease of cervids, now identified in 22 United States, 2 Canadian provinces and Korea. One hallmark of CWD is the shedding of infectious prions in saliva, as demonstrated by bioassay in deer. It is also clear that the concentration of prions in saliva, blood, urine and feces is much lower than in the nervous system or lymphoid tissues. Rapid in vitro detection of CWD (and other) prions in body fluids and excreta has been problematic due to the sensitivity limits of direct assays (western blotting, ELISA) and the presence of inhibitors in these complex biological materials that hamper detection. Here we use real-time quaking induced conversion (RT-QuIC) to demonstrate CWD prions in both diluted and prion-enriched saliva samples from asymptomatic and symptomatic white-tailed deer. CWD prions were detected in 14 of 24 (58.3%) diluted saliva samples from CWD-exposed white-tailed deer, including 9 of 14 asymptomatic animals (64.2%). In addition, a phosphotungstic acid enrichment enhanced the RT-QuIC assay sensitivity, enabling detection in 19 of 24 (79.1%) of the above saliva samples. Bioassay in Tg[CerPrP] mice confirmed the presence of infectious prions in 2 of 2 RT-QuIC-positive saliva samples so examined. The modified RT-QuIC analysis described represents a non-invasive, rapid ante-mortem detection of prions in complex biologic fluids, excreta, or environmental samples as well as a tool for exploring prion trafficking, peripheralization, and dissemination.

Mother to offspring transmission of chronic wasting disease in reeves' muntjac deer

The horizontal transmission of prion diseases has been well characterized in bovine spongiform encephalopathy (BSE), chronic wasting disease (CWD) of deer and elk and scrapie of sheep, and has been regarded as the primary mode of transmission. Few studies have monitored the possibility of vertical transmission occurring within an infected mother during pregnancy. To study the potential for and pathway of vertical transmission of CWD in the native cervid species, we used a small cervid model-the polyestrous breeding, indoor maintainable, Reeves' muntjac deer-and determined that the susceptibility and pathogenesis of CWD in these deer reproduce that in native mule and white-tailed deer. Moreover, we demonstrate here that CWD prions are transmitted from doe to fawn. Maternal CWD infection also appears to result in lower percentage of live birth offspring. In addition, evolving evidence from protein misfolding cyclic amplification (PMCA) assays on fetal tissues suggest that covert prion infection occurs in utero. Overall, our findings demonstrate that transmission of prions from mother to offspring can occur, and may be underestimated for all prion diseases.

Sensitivity of protein misfolding cyclic amplification versus immunohistochemistry in ante-mortem detection of chronic wasting disease

As the only prion disease affecting free-ranging animals, ante-mortem identification of affected cervids has become paramount in understanding chronic wasting disease (CWD) pathogenesis, prevalence and control of horizontal or vertical transmission. To seek maximal sensitivity in ante-mortem detection of CWD infection, this study used paired tonsil biopsy samples collected at various time points from 48 CWD-exposed cervids to compare blinded serial protein misfolding cyclic amplification (sPMCA) with the assay long considered the 'gold standard' for CWD detection, immunohistochemistry (IHC). sPMCA-negative controls (34 % of the samples evaluated) included tissues from mock-inoculated animals and unspiked negative controls, all of which tested negative throughout the course of the study. It was found that sPMCA on tonsil biopsies detected CWD infection significantly earlier (2.78 months, 95 % confidence interval 2.40-3.15) than conventional IHC. Interestingly, a correlation was observed between early detection by sPMCA and host PRNP genotype. These findings demonstrate that in vitro-amplification assays provide enhanced sensitivity and advanced detection of CWD infection in the peripheral tissues of cervids, with a potential role for spike or substrate genotype in sPMCA amplification efficiency.

Detection of sub-clinical CWD infection in conventional test-negative deer long after oral exposure to urine and feces from CWD+ deer

Background

Chronic wasting disease (CWD) of cervids is a prion disease distinguished by high levels of transmissibility, wherein bodily fluids and excretions are thought to play an important role. Using cervid bioassay and established CWD detection methods, we have previously identified infectious prions in saliva and blood but not urine or feces of CWD+ donors. More recently, we identified very low concentrations of CWD prions in urine of deer by cervid PrP transgenic (Tg[CerPrP]) mouse bioassay and serial protein misfolding cyclic amplification (sPMCA). This finding led us to examine further our initial cervid bioassay experiments using sPMCA.

Objectives

We sought to investigate whether conventional test-negative deer, previously exposed orally to urine and feces from CWD+ sources, may be harboring low level CWD infection not evident in the 19 month observation period. We further attempted to determine the peripheral PrP^CWD distribution in these animals.

Methods

Various neural and lymphoid tissues from conventional test-negative deer were reanalyzed for CWD prions by sPMCA and cervid transgenic mouse bioassay in parallel with appropriate tissue-matched positive and negative controls.

Results

PrP^CWD was detected in the tissues of orally exposed deer by both sPMCA and Tg[CerPrP] mouse bioassay; each assay revealed very low levels of CWD prions previously undetectable by western blot, ELISA, or IHC. Serial PMCA analysis of individual tissues identified that obex alone was positive in 4 of 5 urine/feces exposed deer. PrP^CWD was amplified from both lymphoid and neural tissues of positive control deer but not from identical tissues of negative control deer.

Discussion

Detection of subclinical infection in deer orally exposed to urine and feces (1) suggests that a prolonged subclinical state can exist, necessitating observation periods in excess of two years to detect CWD infection, and (2) illustrates the sensitive and specific application of sPMCA in the diagnosis of low-level prion infection. Based on these results, it is possible that low doses of prions, e.g. following oral exposure to urine and saliva of CWD-infected deer, bypass significant amplification in the LRS, perhaps utilizing a neural conduit between the alimentary tract and CNS, as has been demonstrated in some other prion diseases.

Detection of CWD prions in urine and saliva of deer by transgenic mouse bioassay

Chronic wasting disease (CWD) is a prion disease affecting captive and free-ranging cervids (e.g. deer, elk, and moose). The mechanisms of CWD transmission are poorly understood, though bodily fluids are thought to play an important role. Here we report the presence of infectious prions in the urine and saliva of deer with chronic wasting disease (CWD). Prion infectivity was detected by bioassay of concentrated, dialyzed urine and saliva in transgenic mice expressing the cervid PrP gene (Tg[CerPrP] mice). In addition, PrP^CWD was detected in pooled and concentrated urine by protein misfolding cyclic amplification (PMCA). The concentration of abnormal prion protein in bodily fluids was very low, as indicated by: undetectable PrP^CWD levels by traditional assays (western blot, ELISA) and prolonged incubation periods and incomplete TSE attack rates in inoculated Tg(CerPrP) mice (373^±3days in 2 of 9 urine-inoculated mice and 342^±109 days in 8 of 9 saliva-inoculated mice). These findings help extend our understanding of CWD prion shedding and transmission and portend the detection of infectious prions in body fluids in other prion infections.

Corneal ulceration associated with naturally occurring canine herpesvirus-1 infection in two adult dogs

CASE DESCRIPTION

An 8-year-old Labrador Retriever with diabetes mellitus in which bilateral phacoemulsification had been performed 3 weeks earlier was evaluated for acute onset of blepharospasm, and a 7-year-old Miniature Schnauzer with chronic immune-mediated thrombocytopenia was reevaluated for keratoconjunctivitis sicca that had been diagnosed 4 weeks earlier.

CLINICAL FINDINGS

Dendritic corneal ulcerations were detected in both dogs. Canine herpesvirus-1 (CHV-1) was isolated from corneal swab specimens obtained during the initial evaluation of each dog and during recheck examinations performed until the ulcerations were healed. Canine herpesvirus-1 serum neutralization titers were detected in both dogs. Results of virus isolation from oropharyngeal and genital swab specimens were negative for both dogs. The isolated viruses were identified as CHV-1 via immunofluorescence, transmission electron microscopy, PCR assay, and gene sequencing. Negative controls for PCR assay and virus isolation included conjunctival swab specimens from 50 dogs without extraocular disease and corneal swab specimens from 50 dogs with corneal ulcers, respectively.

TREATMENT AND OUTCOME

Lesions resolved in both dogs after topical administration of idoxuridine or trifluridine and discontinuation of topically administered immunosuppressive medications.

CLINICAL RELEVANCE

To the authors' knowledge, this is the first report of corneal ulcerations associated with naturally occurring CHV-1 infection and may represent local ocular recrudescence of latent CHV-1 infection. The viruses isolated were identified as CHV-1, and the morphology, antigenicity, and genotype were similar to those for CHV-1 isolates obtained from a puppy that died from systemic CHV-1 infection.

Polymerase chain reaction screening for DNA viruses in paraffin-embedded brains from dogs with necrotizing meningoencephalitis, necrotizing leukoencephalitis, and granulomatous meningoencephalitis

The objective of this investigation was to determine whether or not herpesvirus (herpes-), adenovirus (adeno-), or canine parvovirus DNA is present in the brains of dogs with necrotizing meningoencephalitis (NME), necrotizing leukoencephalitis (NLE), and granulomatous meningoencephalitis (GME). Paraffin-embedded brain specimens from 12 histopathologically confirmed dogs with NME, 3 with NLE, and 7 with GME were screened for viral DNA with degenerate herpes- and adenovirus polymerase chain reaction (PCR) and a canine parvovirus-specific PCR. Positive-control specimens included genomic viral DNA and paraffin-embedded tissues from dogs with confirmed herpes-, adeno-, or canine parvovirus infections. Herpes-, adeno-, or canine parvovirus DNA was amplified by PCR from the corresponding positive-control specimens. Negative controls included 7 dogs with various brain disorders and produced no viral amplicons. The 22 dogs with NME, NLE, and GME were negative for viral DNA. Additional studies testing for other viruses or inherited genetic mutations are warranted to gain insight into the etiologies of NME, NLE, and GME. We discuss potential etiologies and provide a clinical and histopathologic overview of these common canine encephalitides.

Use of a multiplex polymerase chain reaction assay in the antemortem diagnosis of toxoplasmosis and neosporosis in the central nervous system of cats and dogs

OBJECTIVE

To develop a multiplex polymerase chain reaction (PCR) assay for the detection of Toxoplasma gondii and Neospora caninum DNA in canine and feline biological samples. SAMPLE POPULATION; Biological samples from 7 cats with systemic (n = 4) or CNS (3) toxoplasmosis, 6 dogs with neospora- or toxoplasma-associated encephalitis, and 11 animals with nonprotozoal disease.

PROCEDURE

Primers for T gondii, N caninum, and the canine ferritin gene (dogs) or feline histone 3.3 gene (cats) were combined in a single PCR assay. The DNA was extracted from paraffin-embedded brain tissue, CSF, or skeletal muscle. The PCR products with positive results were cloned, and sequence identity was confirmed.

RESULTS

Of 7 cats and 4 dogs with immunohistochemical or serologic evidence of toxoplasmosis, PCR results were positive for all cats and 3 dogs for T gondii, and positive for T gondii and N caninum for 1 dog. Another dog had negative PCR results for both parasites. Of 2 dogs with immunohistochemical or serologic evidence of neosporosis, PCR results were positive for 1 for N caninum and positive for the other for T gondii. All negative-control samples yielded negative results for T gondii and N caninum on the PCR assay.

CONCLUSIONS AND CLINICAL RELEVANCE

Standard tests for toxoplasmosis or neosporosis associated with the CNS rely on serologic, histologic, or immunohistochemical analysis and can be difficult to interpret. The multiplex PCR assay with built-in control reactions could be a complementary clinical tool for the antemortem diagnosis of toxoplasmosis or neosporosis associated with the CNS.

Polymerase chain reaction (PCR) amplification of parvoviral DNA from the brains of dogs and cats with cerebellar hypoplasia

Cerebellar hypoplasia in cats is caused most commonly by an in utero or perinatal infection with feline panleukopenia virus (parvovirus). Cerebellar hypoplasia has been reported infrequently in dogs, but no viral etiology has been identified to date. DNA was extracted from archival, paraffin-embedded, cerebellar tissue from 8 cats and from 2 canine littermates with cerebellar hypoplasia, 2 canine littermates with cerebellar cortical abiotrophy, 6 dogs with congenital cerebellar vermal defects, 1 dog with congenital hydranencephaly, and 15 dogs and cats with various encephalitdes. The DNA extracted from each cerebellum was subject to polymerase chain reaction (PCR) amplification by 3 primer pairs specific for parvovirus DNA. Sequence analysis of PCR products from each of the 8 cats and 2 dogs with cerebellar hypoplasia confirmed their identity with parvoviral DNA. The 6 dogs with cerebellar vermal defects, 2 dogs with cortical abiotrophy, 1 dog with congenital hydranencephaly, and all control samples were PCR negative for parvovirus. Parvoviral structural proteins were not identified by immunohistochemistry in either dog with cerebellar hypoplasia. This study shows that parvoviral DNA can be amplified from feline and canine archival brain tissue and that cerebellar hypoplasia in dogs might be associated with in utero parvovirus infection.

A cross-sectional study of IGF-I determinants in women

Evidence is accumulating that elevated circulating insulin-like growth factor I (IGF-I) is related to increased cancer risk. The identification of hormonal, reproductive and lifestyle characteristics influencing its synthesis and bioavailability is of particular interest. Data from 400 women, who served as controls in two case-control studies nested within the same prospective cohort study, were combined. IGF-I, IGF-binding proteins 1, 2 and 3 (IGFBP-1, -2, -3) and insulin were measured in serum samples from all subjects and cotinine in 186 samples. Age appears to be the most important determinant of total IGF-I levels in women. Anthropometric measures, such as body mass index (BMI) or waist-to-hip ratio (WHR) do not seem to influence total IGF-I concentrations in peripheral blood, but may modulate IGF-I bioavailability through insulin-dependent changes in IGFBP-1 and -2 concentrations. Age at menarche, phase of the menstrual cycle at blood draw, parity, menopause, past oral contraceptive or hormone replacement therapy use, and tobacco smoking do not appear to exert an independent effect on IGF-I and its binding proteins. There was some suggestion that regular physical activity may increase total IGF-I and that women with positive family history of breast cancer might have higher IGF-I levels than those without such diagnosis in their relatives.

A prospective study of insulin-like growth factor-I, IGF-binding proteins-1, -2 and -3 and lung cancer risk in women

Insulin-like growth factor-I (IGF-I) has mitogenic and anti-apoptotic properties and has been implicated in the development of breast, colorectum, prostate and lung cancer. IGF binding proteins (IGFBPs) are not only carrier proteins for IGFs but also hold a central position in IGF ligand-receptor interactions through influences on the bioavailability and distribution of IGFs in the extracellular environment. A case-control study nested within the New York University Women's Health Study Cohort included 93 women diagnosed with lung cancer at least 6 months after recruitment into the study. Two controls (n = 186) were matched to each case on age, date of blood sampling, menopausal status, day of menstrual cycle and questionnaire data of smoking status at the time of blood donation. Serum IGF-I, IGFBP-1, -2 and -3, insulin and cotinine were measured. Mean serum levels of IGF-I, IGFBP-1, -2 and -3 were not significantly different between the case and control groups. Univariate logistic regression analyses showed no association of lung cancer risk with serum levels of IGF-I or any of the IGFBPs. These results remained virtually the same in multivariate analyses, including adjustment for cotinine, time since last meal, BMI, IGF-I or IGFBP-3, respectively. Exclusion of cases diagnosed within 3 years of recruitment in the cohort, or restriction of the analyses to adenocarcinomas only, did not alter these results. Our study does not offer evidence in support of an association between prediagnostic serum levels of IGF-I or IGFBP-1, -2 and -3 and lung cancer risk in women.

Acute respiratory response to prolonged, moderate levels of sidestream tobacco smoke

Environmental tobacco smoke (ETS) is a significant component of indoor air pollution yet the acute upper respiratory response has not been well studied. The goal of this study was to determine the response of healthy subjects to moderate levels of sidestream tobacco smoke (SS). Twenty-three subjects were challenged on 2 separate days to clean air or SS (2 h, 15 ppm carbon monoxide, at rest). Subjects completed symptom questionnaires, posterior rhinomanometry, and body plethysmography. Average total and differential cell counts and albumin concentration were determined on nasal lavage samples. The urinary cotinine: creatinine ratio was used as a biomarker of exposure. Following SS exposure, irritant and rhinitis symptoms increased, nasal resistance rose from 4.9+/-0.4 to 6.3+/-0.6 cm H2O/L/s and specific airway conductance decreased from 0.14+/-0.01 to 0.13+/-0.01 cm H2O(-1) s(-1). Total cell counts, neutrophils, and albumin were unchanged. An increased nasal congestive response did not correlate with an increased cotinine: creatinine ratio. A history of ETS rhinitis did not predict an increased group response to smoke, but individuals with the largest physiologic and inflammatory response were historically ETS sensitive. In summary, healthy normal subjects demonstrate nasal congestion with exposure to moderate levels of SS without evidence of increased nasal vascular permeability.

Factors modifying exposure to environmental tobacco smoke in children (Athens, Greece)

The aim of the study was to investigate individual, family, and environmental factors which may modify exposure of children to environmental tobacco smoke (ETS). A total of 2,108 children of both genders, aged up to 14 years old, were enrolled in the study. Parents of the children provided information concerning several factors that may affect exposure to ETS. Cotinine-to-creatinine ratios in spot urine samples were measured for each child. These values were logtransformed and regressed on a series of exposure variables. Among children, 73 percent were exposed to ETS generated by at least one smoker in the household. Exposure to ETS was affected by the following factors: cigarettes smoked by parents while the child was at home (increase by 37 percent per 10 cigarettes daily, 95 percent confidence interval [CI] = 32-43 percent); precautions taken by parents (no cf yes, increase by 38 percent, CI = 24-54 percent); child's age (decrease by nine percent per year, CI = -11-8 percent); gender (male lower than female by 13 percent, CI = -21-3 percent); day of the week (Monday cf Tuesday-through-Sunday, increase by 28 percent, CI = 14-44 percent); floor surface area (decrease by nine percent per 20 m2, CI = -14-5 percent); heating (central cf non-central decrease by 14 percent, CI = -25-2 percent); maternal education (decrease by nine percent per five years, CI = -18-0 percent); paternal education (decrease by seven percent per five years, CI = -15-2 percent). It is concluded that several household-related factors affect exposure to ETS and that this exposure can be reduced by about one-third by simple precautions taken by smoking parents.

Do the nonsmoking daughters of smokers tend to marry smokers? Implications for epidemiological research on environmental tobacco smoke: the IARC collaborative study

The IARC collaborative study on exposure to environmental tobacco smoke (ETS) involved collecting interview data and biochemical indicators of exposure from 1369 nonsmoking women in 13 centers in 10 countries. Information on childhood and adulthood exposure to other people's smoke and duration of this exposure from both parents and spouse was gathered at the interview. Of the 900 women whose husbands smoked (current or exsmokers), 71.3% had one or both parents who smoked (predominantly the father), whereas among the 277 women married to never-smokers, only 60.3% had at least one parent who smoked. The odds ratio for the daughter of a smoker to marry a smoker was, therefore, 1.64 (95% confidence interval = 1.24-2.17; P > 0.001), and there was an exposure-response relation between the number of years of childhood exposure to ETS from the parents and the likelihood of being married to a smoker. These results show that nonsmoking women married to smokers are more likely to have been exposed to tobacco pollution during their whole life. Because the duration of exposure is known to be important in the genesis of lung cancer, some of the excess risk of lung cancer in nonsmoking women married to smokers may be due exposure to ETS from parents during childhood.

Effects of alcohol and prescription and over-the-counter drug use on liver enzyme profiles

Liver function tests are commonly ordered during routine checkups or in an effort to identify the cause of underlying disease. Elevated liver enzymes usually indicate a disease or an insult to the liver, the main causes of which can be hepatitis (caused by virus infection or chemical exposures) or cirrhosis of the liver due to alcohol abuse. Results from the Metropolitan Life Insurance Testing Laboratory confirm national data showing a slow rise in the percentage of "free-living" persons with elevated liver enzymes. The percentage of "abnormal" results increased despite unchanged analytic methods or quality control measures during the data gathering period. In addition, the proportions of abnormal enzyme levels have increased while U.S. per capita alcohol consumption has decreased and sales of over-the-counter medications that elevate liver enzymes have increased. Thus, it is increasingly more difficult to determine the true cause of elevated liver enzymes. As more Americans self-medicate and as more prescription drugs become available over-the-counter, which can have subtle or overt effects on liver enzyme secretion, the causes for abnormal enzyme levels will remain difficult to interpret. Continued monitoring of liver enzyme levels and the prevalence of drug and alcohol use are necessary to determine if the noted rise in abnormal levels is associated with increased morbidity or adverse outcome.

Validity of urinary biomarkers of exposure to tobacco smoke following prolonged storage

BACKGROUND

The utility of using biomarkers of smoking in epidemiological studies depends not only on the validity and precision of the laboratory procedure but often on the long-term stability of the analytes of interest in stored biological samples.

METHODS

We retrieved urine samples collected in 1976-1977 from women included in a cohort study in Utrecht and for whom information on smoking status was available. Creatinine and thiocyanate were measured in 1976-1977 on fresh samples. Cotinine and creatinine were analysed in 1988 on urine stored at -20 degrees C.

RESULTS

Measurements of creatinine more than 10 years apart showed a correlation of 0.95 and equal means. Cotinine measurements made in 1988 allowed a clear separation of smokers and non-smokers (sensitivity 92%, specificity 100%), suggesting that concentrations retained their discriminant value even after 10 years of storage.

CONCLUSION

These results emphasize the possibilities offered by long-term storage, under proper conditions, of biological samples for subsequent determination of analytes which may emerge as the study progresses.

Misclassification of smoking status among women in relation to exposure to environmental tobacco smoke

In studies of the health effects of exposure to environmental tobacco smoke (ETS), misclassification of active smokers has the potential to bias the estimates of disease risk. Biochemical validation of exposure to ETS can provide objective evidence of current smoking status in epidemiological studies. Intrinsic to this effort is the establishment of appropriate cut-off points for the measurements of tobacco biomarkers. Within a collaborative study on ETS co-ordinated by the International Agency for Research on Cancer, questionnaire data and urine samples were collected from 1,369 women at 13 centres in 10 countries. Forty seven of these women had urine cotinine levels above 50 ng.mg-1 creatinine, a level used to discriminate smokers from nonsmokers in previous studies. The distributions of the subjects across cotinine values and self-reported exposure to ETS was consistent with the association, at one extreme, of moderate cotinine levels (50-150 ng.mg-1) with very high exposure to ETS, and, at the other extreme, of very high cotinine levels indicating actual use of nicotine-containing products in women with low ETS exposure. Using the cut-off point of 150 ng.mg-1, only 1.5% of the alleged nonsmokers were reclassified as current light smokers. Potential bias due to smoker misclassification is very unlikely to be responsible for the increased health risks observed in epidemiological studies on ETS.

Cholesterol screening in a community health promotion program: epidemiologic results from a biracial population

The prevalence and interrelationship of high blood cholesterol levels with other cardiovascular disease risk factors were studied in a biracial suburb of New York City. Participants in community-based screenings to determine blood cholesterol levels have been predominantly white women in older age groups, highly educated and nonsmokers. To reach a more representative segment of a local population and promote healthy lifestyle behaviors, cholesterol screenings were conducted within an ongoing health promotion program in Mount Vernon, NY. Plasma cholesterol levels were determined for 5,011 participants, including 2,308 whites and 1,778 blacks. Of the men, 29 percent had high cholesterol levels; among women, it was 27 percent. Of the men with high levels, half had levels greater than 200 milligrams per deciliter, as did 55 percent of the women. After statistical adjustments were made for age and other risk factors for high blood cholesterol, mean cholesterol levels were higher for whites than blacks. The level for white men was 204 milligrams per deciliter; for women, 212. For black men, the level was 199 milligrams per deciliter; for women, 208, P < .10. Hispanic men had levels of 199, P < .10. The levels for Hispanic women (203 milligrams per deciliter) were significantly lower than that of white women. Among whites who smoked more than 1 pack of cigarettes per day, mean cholesterol levels were 11 milligrams per deciliter higher than for those who never smoked or were light smokers (0, 1-20 cigarettes per day, P < .10). There were too few who smoked more than 1 pack to test this association adequately among blacks. The mean cholesterol levels for hypertensive black men were 10 milligrams per deciliter greater than for black men with normal blood pressure (P<.10).

Environmental tobacco smoke exposure as determined by cotinine in black and white young adults: the CARDIA Study

Biologic markers have provided a direct method for assessing exposure to environmental tobacco smoke (ETS) and yet few studies have used these techniques to document exposure in general samples of nonsmokers. Exposure to ETS was assessed by serum cotinine and self-report in 3300 nonsmoking participants in the CARDIA study. Nonsmoking status was validated by a cotinine level of < 14 ng/ml. Twenty-eight percent of the 18- to 30-year-olds were exposed to ETS as determined by a detectable serum cotinine level (2-13 ng/ml); prevalence of exposure was higher among blacks than whites (32% vs 24%, P < 0.001). Similarly, ETS exposure as defined by self-report (hours/week) was higher in blacks, particularly for exposure in the home and in other small areas. Multivariate predictors of cotinine-determined exposure included reported exposure, male gender, lower education, past smoking history, and spending time with smokers. Only among current users of marijuana, 20% of the sample, was the black race found to be an independent predictor of exposure. The prevalence of ETS exposure is higher in blacks than whites, as documented by self-report and confirmed by serum cotinine levels. Other correlates of exposure include demographic factors and factors which may be surrogate measures of exposure.

Measuring exposure to environmental tobacco smoke in studies of acute health effects

The relations among three methods of measuring exposure to environmental tobacco smoke, questionnaires, urinary cotinine, and a passive monitor for ambient nicotine, were investigated in a study of 48 children in Minnesota in 1989. Subjects were all under 2 years of age and did not attend day care. Passive nicotine monitors were placed in the activity room and the child's bedroom for 1 week, urine samples were collected at the beginning and end of the week for cotinine analysis, and a detailed questionnaire concerning cigarette smoking was administered at the end of the week. These same measures were obtained weekly for 8 weeks for 22 of the children. Among households with smokers, concentrations of ambient nicotine and urinary cotinine were lowest when the father smoked, intermediate when the mother smoked, and highest when both parents smoked. Activity room concentrations were highly correlated with both urinary cotinine (r = 0.81) and the total number of cigarettes smoked in the house (r = 0.86). Regression equations indicated that knowing who smoked in the house was a more important predictor of ambient nicotine than knowing the amount smoked. Both urinary cotinine and ambient nicotine demonstrated variability over time, although ambient nicotine was less variable. In addition, 100% of possible ambient nicotine samples were collected in contrast to 80% of urine samples. The results of the study suggest that both urinary cotinine and ambient nicotine provide better information about the exposure of young children to environmental tobacco smoke than questionnaire data alone, and that ambient nicotine may be the more useful in this population based on its greater stability and ease of collection.

The interaction of sociological and biological factors in adolescent cigarette smoking

This article considers the interaction of social and biological factors in the context of adolescent cigarette smoking. Parent and peer smoking are the sociological variables and testosterone is the biological indicator. The subjects are 212 males and females 12-14 years of age. The findings support the interaction model, suggesting that both sociological and biological factors are necessary for understanding adolescent smoking.

Passive smoking and middle ear effusion among children in day care

One hundred thirty-two children who attended a research day-care center were studied to determine whether passive tobacco smoke exposure was associated with an increased rate of otitis media with effusion or with an increased number of days with otitis media with effusion during the first 3 years of life. Based on preliminary studies, a serum cotinine concentration of greater than or equal to 2.5 ng/mL was considered indicative of exposure to tobacco smoke. Otitis media with effusion was diagnosed using pneumatic otoscopy by nurse practitioners and pediatricians who reviewed the children's health status each weekday. The 87 children with serum cotinine concentrations greater than or equal to 2.5 ng/mL had a 38% higher rate of new episodes of otitis media with effusion during the first 3 years of life than the 45 children with lower or undetectable serum cotinine concentrations (incidence density ratio = 1.38, 95% confidence interval 1.21 to 1.56). The average duration of an episode of otitis media with effusion was 28 days in the children with elevated cotinine concentrations and 19 days in the children with lower cotinine concentrations (P less than .01). It is estimated that 8% of the cases of otitis media with effusion in this population and 17.6% of the days with otitis media with effusion may be attributable to exposure to tobacco smoke.

A cholesterol reduction demonstration project: results from a challenge between two cities

A competition was conducted between Jackson, MS and Lansing, MI to reduce blood cholesterol levels among self-selected individuals who were generally at high risk for elevated coronary heart disease. Baseline plasma cholesterol levels were measured and risk factor data were recorded for 13,710 participants in Jackson and 6,719 in Lansing (6.8% and 5.1% of the total populations, respectively). A six month educational campaign was conducted in both cities which included nutritional seminars, television shows, newspaper advertisements etc. From Jackson, 6,244 participants returned for the follow-up screening, and 2,404 from Lansing (46% and 36%). Subjects who reported changes in their diets had an average cholesterol reduction of 19 mg/dl (9%) in Jackson, and 2 mg/dl (1%) in Lansing (after adjustment for sex, baseline level, and age, P less than 0.01). In Lansing, participants were less likely to have college degrees, and were more likely to have participated because of concern with previously determined elevated cholesterol levels than Jackson participants.

Misclassification of smoking status in the CARDIA study: a comparison of self-report with serum cotinine levels

BACKGROUND

Although widely used in epidemiological studies, self-report has been shown to underestimate the prevalence of cigarette smoking in some populations.

METHODS

In the CARDIA study, self-report of cigarette smoking was validated against a biochemical marker of nicotine uptake, serum cotinine.

RESULTS

The prevalence of smoking was slightly lower when defined by self-report (30.9%) than when defined by cotinine levels equal to or greater than 14 ng/mL (32.2%, P less than .05). The misclassification rate (proportion of reported nonsmokers with cotinine levels of at least 14 ng/mL) was 4.2% and was significantly higher among subjects who were Black, had a high school education or less, or were reported former smokers. Possible reasons for misclassification include reporting error, environmental tobacco smoke, and an inappropriate cutoff point for delineation of smoking status. Using self-report as the gold standard, the cotinine cutoff points that maximized sensitivity and specificity were 14, 9, and 15 ng/mL for all, White, and Black subjects, respectively. The misclassification rate remained significantly higher in Black than in White subjects using these race-specific criteria.

CONCLUSIONS

Misclassification of cigarette smoking by self-report was low in these young adults; however, within certain race/education groups, self-report may underestimate smoking prevalence by up to 4%.

Passive smoking during the first year of life

BACKGROUND AND PURPOSE

A description of passive smoking during the first year of life might assist planning preventive efforts.

METHODS

Changes in the ecology of passive smoking were investigated in a sample of infants in central North Carolina followed from birth to one year of age.

RESULTS

The prevalence of tobacco smoke absorption, indicated by excretion of cotinine, increased from 53 percent to 77 percent (95% CI of difference: 14, 35) during the first year of life. Most infants (92 percent) excreting cotinine at three weeks of age were also excreting it at one year. Moreover, 61 percent of infants not excreting cotinine at age three weeks were excreting it at one year. This increase reflected an increased exposure to household and, particularly, nonhousehold sources of smoke; the proportion of infants exposed to nonhousehold smokers increased from 14 percent to 36 percent.

CONCLUSIONS

These findings suggest that prevention of the onset of passive smoking should begin very early.

Diet and serum lipids in vegan vegetarians: a model for risk reduction

The lipid levels and dietary habits of 31 Seventh-Day Adventist vegan vegetarians (aged 5 to 46 years) who consume no animal products were assessed. Mean serum total cholesterol (3.4 mmol/L), low-density-lipoprotein cholesterol (1.8 mmol/L), and triglyceride (0.8 mmol/L) levels were lower than expected values derived from the Lipid Research Clinics Population Studies prevalence data. Mean high-density-lipoprotein cholesterol (1.3 mmol/L) was comparable to expected values. Analysis of quantitative food frequency data showed that vegans had a significantly lower daily intake of total energy, percentage of energy from fat (31% vs 38%), total fat, saturated fat, monounsaturated fatty acids, cholesterol, and protein and a significantly higher intake of fiber than a sample of matched omnivore controls. Vegans' food intake was also compared with expected values, matched for sex and age, derived from the second National Health and Nutrition Examination Survey and Continuing Survey of Food Intakes by Individuals 24-hour recall data. The vegan diet was characterized by increased consumption of almonds, cashews, and their nut butters; dried fruits; citrus fruits; soy milk; and greens. We conclude from the present study that a strict vegan diet, which is typically very low in saturated fat and dietary cholesterol and high in fiber, can help children and adults maintain or achieve desirable blood lipid levels.

Cigarette smoking and plasma cholesterol

Plasma cholesterol levels were determined for 51,723 participants of community-based cholesterol screenings in 10 United States cities during 1988. Among white adult men and women under the age of 60 without other cardiovascular disease risk factors, a dose-response relationship was found between the number of cigarettes smoked per day and increasing levels of plasma cholesterol. In men aged 18 to 60 years, average plasma cholesterol increased by 0.33 mg/dl for each cigarette smoked (p less than 0.001); in women aged 31 to 50 years, average plasma cholesterol increased by 0.48 mg/dl for each cigarette smoked (p less than 0.001). Plasma cholesterol levels among ex-smokers were found to be similar to those of nonsmokers. No association between cigarette smoking and levels of plasma cholesterol was observed in men and women over age 60. Possible mechanisms for this observed relationship include an antiestrogenic effect of cigarette smoking that makes the observation more noticeable in younger female cohorts, enhanced lipolysis that increases levels of plasma free fatty acids, or differences in dietary intake between smokers and nonsmokers.

Dietary patterns of female nonsmokers with and without exposure to environmental tobacco smoke

The relationship of passive smoking to diet was examined in 82 female nonsmokers who provided a quantitative diet history in 1986. Exposure to environmental tobacco smoke (ETS) was assessed by urinary cotinine measurement. Mean values for each dietary variable, adjusted for age, ethnicity, education, and last week's ethanol intake, were compared among unexposed women and women with low or high ETS exposure. Linear relationships with amount of ETS exposure were also sought. Intakes of beta-carotene and cholesterol were found to be inversely related to ETS exposure. Since these nutrients have been associated with lung cancer risk, they are potential confounders of the passive-smoking/lung-cancer relationship. Although we estimate the confounding effect of these dietary factors to be modest, they should be measured carefully in future studies of this relationship.

Exposure of nonsmoking women to environmental tobacco smoke: a 10-country collaborative study

The interpretation and interpretability of epidemiologic studies of environmental tobacco smoke (ETS) depend largely on the validity of self-reported exposure. To investigate to what extent questionnaires can indicate exposure levels to ETS, an international study was conducted in 13 centers located in 10 countries, and 1,369 nonsmoking women were interviewed. The present paper describes the results of the analysis of self-reported recent exposure to ETS from any source in relation to urinary concentrations of cotinine. Of the total, 19.7 percent of the subjects had nondetectable cotinine levels, the median value was 6 ng/mg, and the cut-point of the highest decile was 24 ng/mg. The proportion of subjects misreporting their active smoking habit was estimated at between 1.9 and 3.4 percent, depending on whether cut-points of 50 or 100 ng/mg creatinine were used. Large and statistically significant differences were observed between centers, with the lowest values in Honolulu, Shanghai, and Chandigarh, and the highest in Trieste, Los Angeles, and Athens. Mean cotinine/creatinine levels showed a clear linear increase from the group of women not exposed either at home or at work, to the group of those exposed both at home and at work. Values were significantly higher for women exposed to ETS from the husband but not at work, than for those exposed at work but not from the husband. The results of linear regression analysis indicated that duration of exposure and number of cigarettes to which the subject reported being exposed were strongly related to urinary cotinine. ETS exposure from the husband was best measured by the number of cigarettes, while exposure at work was more strongly related to duration of exposure. After adjustment of number of cigarettes for volume of indoor places, a similar increase in cotinine (5 ng/mg) was predicted by the exposure to 7.2 cigarettes/8 h/40 m3 from the husband and 17.9 cigarettes/8 h/40 m3 at work. The results indicate that, when appropriately questioned, nonsmoking women can provide a reasonably accurate description of ETS exposure. Assessment of individual exposure to ETS should focus on daily duration and volume of indoor places where exposure occurred.

Racial differences in serum cotinine levels among smokers in the Coronary Artery Risk Development in (Young) Adults study

Cotinine was measured in the serum of nearly all 5,115 18-30 year old, Black and White, men and women participating in the Coronary Artery Risk Development in (Young) Adults Study, 30 percent of whom reported current cigarette smoking. Ninety-five percent of the reported smokers had serum cotinine levels indicative of smoking (greater than 13 ng/ml). The median cotinine level was higher in Black than White smokers (221 ng/ml versus 170 ng/ml; 95 percent CI for difference: 34, 65) in spite of the fact that estimated daily nicotine exposure and serum thiocyanate were higher in Whites. The difference persisted after controlling for number of cigarettes, nicotine content, frequency of inhalation, weekly sidestream smoke exposure, age, gender, and education. A reporting bias and nicotine intake were ruled out as explanations for the racial difference suggesting that the metabolism of nicotine or the excretion of cotinine may differ by race. Racial differences in cotinine levels may provide clues to the reasons for the observed lower cessation rates and higher rates of some smoking-related cancers in Blacks.

Population characteristics and cigarette yield as determinants of smoke exposure

Relationships of population characteristics, smoking history, and cigarette yield with smoke exposure as measured by peripheral blood concentrations of thiocyanate, carboxyhemoglobin, nicotine and cotinine were sought in 170 male smokers. This population of smokers had significant elevations of serum thiocyanate, blood carboxyhemoglobin and plasma nicotine and cotinine concentrations as compared with an equal number of age- and sex-matched nonsmokers and these concentrations correlated significantly with past 24-hour cigarette consumption. Although the nicotine yield of the cigarette correlated significantly with plasma cotinine and marginally with plasma nicotine, the reduction in plasma nicotine and cotinine was not proportionate to the reduced yield of the cigarettes, suggesting that smokers partially compensate for the lower yields of their cigarettes. Blood levels of carboxyhemoglobin, nicotine and cotinine were also significantly associated with the weight of the subjects, presumably due to the relationship between weight and the volume of distribution. Univariate and multiple regression analyses provided evidence that coffee and alcohol consumption and years smoked also may be important determinants of smoke exposure.

Puffing topography as a determinant of smoke exposure

Puffing topography variables were measured in a well-characterized, male population smoking their own brand of cigarette. Of the puffing topography variables, interpuff interval appeared to be the primary determinant of blood concentrations of smoke constituents: however, preliminary data in a homogeneous population according to the nicotine yield of their cigarette suggest that total puff volume per cigarette may also be a significant determinant of blood levels of smoke constituents. Smokers of low nicotine yield cigarettes partially compensated for these lower yields by increasing the total volume puffed per cigarette. Observed differences in puffing topography associated with increased daily cigarette consumption and cumulative smoking history were consistent with a higher smoke exposure per cigarette. Further, although both alcohol and coffee consumption are associated with present and cumulative smoking history, coffee consumption is uniquely associated with differences in puffing topography consistent with a higher smoke exposure per cigarette. However, by multiple regression analyses, neither coffee nor alcohol consumption histories added significantly to the prediction of blood concentrations of smoke constituents over that obtained by smoking history and puffing topography.

Use of smokeless tobacco in a group of professional baseball players

This paper describes the smokeless tobacco use practices and oral health problems of members of a minor league professional baseball team. Seventeen of 25 ball-players reported current use of smokeless tobacco. Gingival recession and lesions in the oral mucosa were more common in smokeless tobacco users than nonusers. Reported use of smokeless tobacco was greater during baseball season than in the off-season. Of the 19 current and past users, 15 reported first using smokeless tobacco after entering professional baseball. To discourage the use of smokeless tobacco by professional athletes, teams should stop accepting free samples and do a better job educating players about health consequences associated with use.