Mapping structural variants to rare disease genes using long-read whole genome sequencing and trait-relevant polygenic scores

Recent studies have revealed the pervasive landscape of rare structural variants (rSVs) present in human genomes. rSVs can have extreme effects on the expression of proximal genes and, in a rare disease context, have been implicated in patient cases where no diagnostic single nucleotide variant (SNV) was found. Approaches for integrating rSVs to date have focused on targeted approaches in known Mendelian rare disease genes. This approach is intractable for rare diseases with many causal loci or patients with complex, multi-phenotype syndromes. We hypothesized that integrating trait-relevant polygenic scores (PGS) would provide a substantial reduction in the number of candidate disease genes in which to assess rSV effects. We further implemented a method for ranking PGS genes to define a set of core/key genes where a rSV has the potential to exert relatively larger effects on disease risk. Among a subset of patients enrolled in the Genomic Answers for Kids (GA4K) rare disease program (N=497), we used PacBio HiFi long-read whole genome sequencing (lrWGS) to identify rSVs intersecting genes in trait-relevant PGSs. Illustrating our approach in Autism (N=54 cases), we identified 1,827 deletions, 158 duplications, 619 insertions, and 14 inversions overlapping putative core/key PGS genes. Additionally, by integrating genomic constraint annotations from gnomAD, we observed that rare duplications overlapping putative core/key PGS genes were frequently in higher constraint regions compared to controls (P = 2×10-04). This difference was not observed in the lowest-ranked gene set (P = 0.18). Overall, our study provides a framework for the annotation of long-read rSVs from lrWGS data and prioritization of disease-linked genomic regions for downstream functional validation of rSV impacts. To enable reuse by other researchers, we have made SV allele frequencies and gene associations freely available.

Complex trait associations in rare diseases and impacts on Mendelian variant interpretation

Emerging evidence implicates common genetic variation - aggregated into polygenic scores (PGS) - impacting the onset and phenotypic presentation of rare diseases. In this study, we quantified individual polygenic liability for 1,151 previously published PGS in a cohort of 2,374 probands enrolled in the Genomic Answers for Kids (GA4K) rare disease study, revealing widespread associations between rare disease phenotypes and PGSs for common complex diseases and traits, blood protein levels, and brain and other organ morphological measurements. We observed increased polygenic burden in probands with variants of unknown significance (VUS) compared to unaffected carrier parents. We further observed an enrichment in overlap between diagnostic and candidate rare disease genes and large-effect PGS genes. Overall, our study supports and expands on previous findings of complex trait associations in rare disease phenotypes and provides a framework for identifying novel candidate rare disease genes and in understanding variable penetrance of candidate Mendelian disease variants.

Direct haplotype-resolved 5-base HiFi sequencing for genome-wide profiling of hypermethylation outliers in a rare disease cohort

Long-read HiFi genome sequencing allows for accurate detection and direct phasing of single nucleotide variants, indels, and structural variants. Recent algorithmic development enables simultaneous detection of CpG methylation for analysis of regulatory element activity directly in HiFi reads. We present a comprehensive haplotype resolved 5-base HiFi genome sequencing dataset from a rare disease cohort of 276 samples in 152 families to identify rare (~0.5%) hypermethylation events. We find that 80% of these events are allele-specific and predicted to cause loss of regulatory element activity. We demonstrate heritability of extreme hypermethylation including rare cis variants associated with short (~200 bp) and large hypermethylation events (>1 kb), respectively. We identify repeat expansions in proximal promoters predicting allelic gene silencing via hypermethylation and demonstrate allelic transcriptional events downstream. On average 30-40 rare hypermethylation tiles overlap rare disease genes per patient, providing indications for variation prioritization including a previously undiagnosed pathogenic allele in DIP2B causing global developmental delay. We propose that use of HiFi genome sequencing in unsolved rare disease cases will allow detection of unconventional diseases alleles due to loss of regulatory element activity.

Insurance denials and diagnostic rates in a pediatric genomic research cohort

PURPOSE

This study aimed to assess the amount and types of clinical genetic testing denied by insurance and the rate of diagnostic and candidate genetic findings identified through research in patients who faced insurance denials.

METHODS

Analysis consisted of review of insurance denials in 801 patients enrolled in a pediatric genomic research repository with either no previous genetic testing or previous negative genetic testing result identified through cross-referencing with insurance prior-authorizations in patient medical records. Patients and denials were also categorized by type of insurance coverage. Diagnostic findings and candidate genetic findings in these groups were determined through review of our internal variant database and patient charts.

RESULTS

Of the 801 patients analyzed, 147 had insurance prior-authorization denials on record (18.3%). Exome sequencing and microarray were the most frequently denied genetic tests. Private insurance was significantly more likely to deny testing than public insurance (odds ratio = 2.03 [95% CI = 1.38-2.99] P = .0003). Of the 147 patients with insurance denials, 53.7% had at least 1 diagnostic or candidate finding and 10.9% specifically had a clinically diagnostic finding. Fifty percent of patients with clinically diagnostic results had immediate medical management changes (5.4% of all patients experiencing denials).

CONCLUSION

Many patients face a major barrier to genetic testing in the form of lack of insurance coverage. A number of these patients have clinically diagnostic findings with medical management implications that would not have been identified without access to research testing. These findings support re-evaluation of insurance carriers' coverage policies.

Genomic answers for children: Dynamic analyses of >1000 pediatric rare disease genomes

PURPOSE

This study aimed to provide comprehensive diagnostic and candidate analyses in a pediatric rare disease cohort through the Genomic Answers for Kids program.

METHODS

Extensive analyses of 960 families with suspected genetic disorders included short-read exome sequencing and short-read genome sequencing (srGS); PacBio HiFi long-read genome sequencing (HiFi-GS); variant calling for single nucleotide variants (SNV), structural variant (SV), and repeat variants; and machine-learning variant prioritization. Structured phenotypes, prioritized variants, and pedigrees were stored in PhenoTips database, with data sharing through controlled access the database of Genotypes and Phenotypes.

RESULTS

Diagnostic rates ranged from 11% in patients with prior negative genetic testing to 34.5% in naive patients. Incorporating SVs from genome sequencing added up to 13% of new diagnoses in previously unsolved cases. HiFi-GS yielded increased discovery rate with >4-fold more rare coding SVs compared with srGS. Variants and genes of unknown significance remain the most common finding (58% of nondiagnostic cases).

CONCLUSION

Computational prioritization is efficient for diagnostic SNVs. Thorough identification of non-SNVs remains challenging and is partly mitigated using HiFi-GS sequencing. Importantly, community research is supported by sharing real-time data to accelerate gene validation and by providing HiFi variant (SNV/SV) resources from >1000 human alleles to facilitate implementation of new sequencing platforms for rare disease diagnoses.

Single-cell analysis of human adipose tissue identifies depot and disease specific cell types

The complex relationship between metabolic disease risk and body fat distribution in humans involves cellular characteristics which are specific to body fat compartments. Here we show depot-specific differences in the stromal vascual fraction of visceral and subcutaneous adipose tissue by performing single-cell RNA sequencing of tissue specimen from obese individuals. We characterize multiple immune cells, endothelial cells, fibroblasts, adipose and hematopoietic stem cell progenitors. Subpopulations of adipose-resident immune cells are metabolically active and associated with metabolic disease status and those include a population of potential dysfunctional CD8+ T cells expressing metallothioneins. We identify multiple types of adipocyte progenitors that are common across depots, including a subtype enriched in individuals with type 2 diabetes. Depot-specific analysis reveals a class of adipocyte progenitors unique to visceral adipose tissue, which shares common features with beige preadipocytes. Our human single-cell transcriptome atlas across fat depots provides a resource to dissect functional genomics of metabolic disease.

Disclosure of cardiac variants of uncertain significance results in an exome cohort

This study examined the impact of disclosing subclassifications of genetic variants of uncertain significance (VUS) on behavioral intentions. We studied return of VUS results to 79 individuals with a cardiomyopathy-associated VUS, subclassified into VUS-high or VUS-low. Primary outcomes were perceived risk (absolute and comparative), perceived severity, perceived value of information, self-efficacy, decision regret, and behavioral intentions to share results and change behaviors. There was no significant difference between the 2 subclasses in overall behavioral intentions (t = 0.023, P = .982) and each of the individual items on the behavioral intentions scale; absolute (t = -1.138, P = .259) or comparative (t = -0.463, P = .645) risk perceptions; perceived value of information (t = 0.582, P = .563) and self-efficacy (t = -0.733, P = .466). Decision regret was significantly different (t = 2.148, P = .035), with VUS-low (mean = 17.24, SD = 16.08) reporting greater regret. Combining the subclasses, perceived value of information was the strongest predictor of behavioral intentions (β = 0.524, P < .001). Participants generally understood the meaning of a genetic VUS result classification and reported satisfaction with result disclosure. No differences in behavioral intentions were found, but differences in decision regret suggest participants distinguish subclasses of VUS results. The perceived value of VUS may motivate recipients to pursue health-related behaviors.

Carcass orientation and drip time affect potential surface water carryover for broiler carcasses subjected to a post-chill water dip or spray1

To estimate the potential for residual antimicrobial solution carryover, surface water accumulation and loss was measured on post-chill carcasses that were either dipped or sprayed with water. For all experiments, broilers were slaughtered, soft or hard scalded, defeathered, and eviscerated. Carcasses were immersion chilled, allowed to drip, and post-chill carcass weight (CW) recorded. For water dip treatment, carcasses were dipped for 0.5 min in water and hung by a wing (n = 33) or a leg (n = 30) and CW recorded at 0, 0.5, 1, 2, and 5 min post-dip. For water spray treatment, individual carcasses were hung by either the wings (n = 35) or legs (n = 34) from a shackle suspended from a scale. Water was sprayed at 80 psi and post-spray CW recorded. Initial water accumulation (0 min) for dipped carcasses was not significantly different (P > 0.05) for carcasses hung by the leg (101.0 g) or wing (108.8 g). Following the 5 min drip time, 31 g of water remained on the carcasses hung by the leg and only 10 g on carcasses hung by the wing (P < 0.05). When carcasses were sprayed with water, initial water accumulation (0 min) was 62 g for carcasses hung by the legs and 60 g for carcasses hung by the wings (P > 0.05). Following the 5 min drip time, 1 g or no water remained on the sprayed carcasses (P > 0.05). Carcasses that were dipped and hung by a leg for 5 min retained significantly more water (31 g) than carcasses that were dipped and hung by a wing (10 g) or sprayed carcasses hung either way (0.3 g) (P < 0.05). Post-chill water dip resulted in significantly higher initial carcass water accumulation than spraying (105 g vs. 61 g, P < 0.05). Carcass orientation during dripping only affected the amount of retained water for dipped carcasses. Dipped carcasses hung by a leg have the highest potential for residual carcass antimicrobial solution carryover and sprayed carcasses hung by either orientation have the lowest potential for residual antimicrobial solution carryover.

Effect of Method of Delivering Nicarbazin to Mallards on Plasma 4,4′-Dinitrocarbanilide Levels and Reproduction

Nicarbazin (NCZ), a coccidiostat used in the poultry industry, has been developed as a contraceptive for resident Canada geese. We tested the efficacy of NCZ as a contraceptive using mallards (Anas platyrhynchos) as a model for Canada geese. Nicarbazin-treated corn was fed ad libitum for 14 d at 0, 750, 1,000, or 1,500 ppm. Plasma and egg levels of 4,4'-dinitrocarbanilide (DNC), the active anticoccidial component of NCZ, differed among treatment groups in a dose-response relationship, but plasma levels did not differ between sexes. Nicarbazin caused a decrease in egg weight, but there was no effect of NCZ on the numbers of eggs laid per female per day. Nicarbazin did not significantly impact bird health. An additional trial tested the effect of the method of NCZ delivery on plasma DNC levels. Mallards were given NCZ daily for 12 d either by gavage with a corn oil suspension, gavage with a water suspension, peroral administration of a capsule, or feeding 500 mg of NCZ/kg of pelleted feed ad libitum. The method of delivery significantly affected plasma DNC levels, with the highest levels in the corn oil suspension group and the lowest levels in the pelleted feed group. This is likely due to decreased availability of NCZ in a pellet compared with gavage with a suspension or capsule. Mallards receiving 34.2 mg of NCZ/kg of BW when fed cracked corn coated with NCZ daily for 14 d had higher plasma DNC levels than those obtained by liquid gavage, capsule, or pelleted NCZ feed. For maximum effect in the field, NCZ should be coated onto corn. A higher concentration of NCZ is needed in pelleted feed to obtain comparable plasma DNC levels to allow for the decreased absorption of DNC.

Evaluation of nicarbazin as a potential waterfowl contraceptive using mallards as a model

Contraception may provide a useful nonlethal management tool to reduce wild bird populations. We tested the efficacy of nicarbazin (NCZ) as a contraceptive for waterfowl and assessed health effects of NCZ, using domestic mallards (Anas platyrhynchos) as a model for Canada geese (Branta canadensis). Mallards were given gelatin capsules containing 0, 8.5, 17.0, or 33.75 mg of NCZ/kg of BW perorally once daily for 14 d. Fecal 4,4'-dinitrocarbanilide (DNC) and fluorescein were evaluated as potential markers of plasma and egg DNC levels. Plasma, egg, and fecal DNC levels differed among treatment groups in a dose response relationship. There were no significant effects on the numbers of eggs laid per female per day, proportion of fertile eggs, proportion of eggs hatching, or egg yolk mottling. Hatchability was 0.55 +/- 0.1 in the control group compared with 0.26 +/- 0.1 in the 33.75 mg/kg of BW group. Degeneration of the vitelline membrane was evident at all treatment levels; severity was dose-related and greater in the outer vitelline membrane than the inner vitelline membrane. No significant health effects were observed for birds treated with NCZ. The heterophil:lymphocyte ratio was elevated during the treatment and posttreatment periods in all groups, indicating birds were experiencing stress due to handling. Fecal DNC levels did not correlate well with plasma DNC levels, likely due to NCZ being administered as a bolus dose rather than being fed ad libitum. Fluorescein correlated well with plasma DNC levels during the treatment period and can therefore be used successfully as a noninvasive marker to determine the approximate amount of NCZ a bird is consuming. As a contraceptive, NCZ likely would have minimal adverse health effects on the target animal, although field studies with the species of interest need to be conducted. Further research using higher NCZ levels needs to be conducted to determine whether NCZ can inhibit reproduction in waterfowl.

Evaluation and significance of tetracycline stability in rabies vaccine baits

Tetracycline is widely used as a biomarker for bait consumption by wildlife; tetracycline is incorporated into bones and teeth and can be detected by fluorescence microscopy several weeks postconsumption. During 2003, the United States Department of Agriculture distributed more than 10 million tetracycline-containing rabies-vaccine baits to control the spread of wildlife vectored rabies to humans, pets, and livestock. To estimate the percentage of target species consuming the baits, raccoons and skunks were collected in baited areas and teeth were analyzed for the presence of the biomarker. Several incidents of low biomarker detection rates prompted an investigation of the stability of the biomarker in the baits. Baits were collected at several points along the manufacturing and distribution chain. Baits were analyzed for free and polymer-bound tetracycline and the less active isomer epitetracycline. Results indicated that a portion of the tetracycline was converted to epitetracycline. Additionally, significant quantities of both compounds were trapped in the polymer, which is homogeneously distributed throughout the bait. The results of this study suggest that approximately 40% of the target quantity of tetracycline was unavailable for absorption. This situation could contribute to low biomarker detection rates and suggests that formulation modification should be considered.

Effectiveness of twenty, twenty-five diazacholesterol, avian gonadotropin-releasing hormone, and chicken riboflavin carrier protein for inhibiting reproduction in Coturnix quail

Contraception may provide a useful nonlethal management tool when it is desirable to reduce populations of birds. We tested the efficacy of 20,25 diazacholesterol, and immunization with avian gonadotropin-releasing hormone (AGnRH-I) and chicken riboflavin carrier protein (cRCP) as contraceptives and investigated their modes of action in Coturnix quail (Coturnix coturnix japonica). Females that were paired with males treated with 20,25 diazacholesterol produced lower percentages of eggs that were fertile and hatched. Females treated with 20,25 diazacholesterol and paired with control males laid fewer eggs, and lower percentages of their eggs were fertile and hatched. Treatment with 20,25 diazacholesterol reduced testosterone levels in males and progesterone levels in females. Nonesterified cholesterol levels were reduced, whereas desmosterol levels increased in birds treated with 20,25 diazacholesterol. Treatment with AGnRH-I and cRCP immunocontraceptive vaccines did not decrease average egg production and hatchability or hormone levels, but this failure might have been due to the vaccination protocol. If registered, wildlife managers may be able to use 20,25 diazacholesterol when other methods, such as lethal control, are undesirable for reducing damage caused by specific breeding behaviors such as the building of nests.

Microsatellite Variation in Red-Winged Blackbirds (Agelaius phoeniceus)

Territorial male red-winged blackbirds from five locations in the United States and Canada were genotyped using a suite of six microsatellite loci. Each population possessed unique alleles, but numbers of alleles per locus (range = 7.3-8.8) and expected multilocus heterozygosities (range = 0.76-0.80) were similar in all populations. Significant overall allele frequency differences were detected between some population pairs, and some pairwise Fst values were significant (but small). However, Fst among populations, although significant, was also small (0.009). Despite revealing low levels of population structure, the high multilocus polymorphism indicates these loci will be valuable in the genetic analysis of behavior and reproductive strategies in this species.

Discordant PKU phenotype in one family due to disparate genotypes and a novel mutation

Classical phenylketonuria (PKU) and mild hyperphenylalaninaemia (MHP) are two ends of the broad diagnostic spectrum in phenylalanine hydroxylase (PAH) deficiency. We have analysed a family in which classical PKU, MHP and a normal phenotype occurred in family members with different mutations. Sequence analysis revealed three mutations segregating in the family. The individual with classical PKU had two previously reported deleterious mutations. A third novel mutation was identified in the other two individuals. This report demonstrates that when discordant phenotypes occur in a family, without protein loading or phenylalanine tolerance test, complete analysis of the PAH gene may be performed in order to support the diagnosis and assist in accurate genetic counselling and patient management.

Risk assessment of an acetaminophen baiting program for chemical control of brown tree snakes on Guam: evaluation of baits, snake residues, and potential primary and secondary hazards

The brown tree snake (Boiga irregularis) is a significant ecological, agricultural, and economic pest on Guam. Acetaminophen has recently been identified as a promising snake toxicant. Subsequent experimentation has shown that acetaminophen-mouse baits are readily consumed by and acutely toxic to browntree snakes. Before implementing an island-wide acetaminophen-mouse baiting program for the reducton of brown tree snake populations,the potential risks to nontarget wildlife must be evaluated. Quantification of nontarget hazards by comparing potential exposure levels to toxicity values suggested a significant level of concern for rodents, cats, pigs, and birds. For these species, subsequent calculations and field and laboratory experiments, which quantified acetaminophen consumption under field conditions, indicated that acetaminophen consumption was minimal. These results indicate that the advantages of using acetaminophen to reduce brown tree snake populations on Guam outweigh the minimal risks to nontarget feral and wildlife species.

Novel field sampling procedure for the determination of methiocarb residues in surface waters from rice fields

Methiocarb was extracted from surface water samples collected at experimental rice field sites in Louisiana and Texas. The sampling system consisted of a single-stage 90-mm Empore extraction disk unit equipped with a battery-powered vacuum pump. After extraction, the C-18 extraction disks were stored in an inert atmosphere at -10 degrees C and shipped overnight to the laboratory. The disks were extracted with methanol and the extracts analyzed by reversed-phase high-performance liquid chromatography with a methanol/water mobile phase. Methiocarb was detected by ultraviolet absorption at 223 nm and quantified with the use of calibration standards. Recoveries from control surface water samples fortified at 5.0, 10, 50, and 100 ng/mL methiocarb averaged 92 +/- 7%. A method limit of detection for methiocarb in rice field surface water was estimated to be 0.23 ng/mL at 223 nm.

Determination of cabergoline by electrospray ionization tandem mass spectrometry: picogram detection via column focusing sample introduction

An electrospray ionization tandem mass spectrometric method was developed for low-picogram detection of an ergot alkaloid, cabergoline, in coyote plasma extracts. Cabergoline is under investigation as an abortifacient in canid species. Central to the successful development of this method was the ability to introduce relatively large sample volumes into the mass spectrometer. This was achieved by focusing the analyte on a conventional high-performance liquid chromatography guard column prior to elution into the spectrometer. Volumes up to at least 900 microL could be injected onto the guard column using a 100% aqueous mobile phase. Cabergoline retained on the column was eluted as a discreet band into the mass spectrometer by the rapid addition of methanol (30%) to the mobile phase. As compared to flow injection sample introduction, the ability to inject larger sample volumes led to a greatly lowered detection limit. Using this technique and a modification of a previously reported extraction procedure, cabergoline could be determined in coyote plasma at concentrations as low as 9 pg of cabergoline/mL of plasma.

Determination of 4,4'-dinitrocarbanilide (DNC), the active component of the antifertility agent nicarbazin, in chicken, duck, and goose plasma

4,4'-Dinitrocarbanilide (DNC) was extracted from chicken, duck, and goose plasma and isolated by reversed-phase high-performance liquid chromatography. DNC was detected by ultraviolet absorbance at 347 nm and quantified by comparison to a calibration standard. Recovery data were determined by analyzing DNC-fortified control plasma. The mean recovery of DNC in fortified chicken plasma samples was 99.7 +/- 1.9% for 0.18 and 9.1 ppm DNC, and in fortified duck and goose plasma samples was 99.5 +/- 4.9% and 101.4 +/- 4.5%, respectively, for 0.18, 9.1, and 18 ppm DNC.

Analysis of pesticide gas cartridges

Charcoal and sodium nitrate, the active ingredients in pesticide gas cartridges, are quantified via carbon analysis and ion chromatography, respectively. Linearity was excellent (R(2) > 0.995) over a range consisting of 50-150% of the target concentration for both ingredients. The coefficient of variation for the replicate analyses of gas cartridges over multiple days was <4% for both analytes. Using the results from the analysis of two batches of gas cartridges, theoretical populations were modeled and used to determine practical sampling strategies to support a quality control program for a gas cartridge manufacturing operation. This modeling indicates that the analysis of three cartridges from each of five different lots would produce mean values for both active ingredients that are within 5% of the true mean >99% of the time.

Solid phase extraction gas chromatography/electron capture detector method for the determination of organochlorine pesticides in wildlife whole blood

A gas chromatographic method for the analysis of 10 organochlorine pesticides in 0.5 mL of whole blood is described. Sample preparation involved an ethyl ether and hexane extraction, followed by a silica solid phase extraction cleanup. The pesticides are quantified by gas chromatography/electron capture detection. Method limits of detection ranged from 1.1 to 5.2 microg/L. The mean and standard deviation for the recovery of 10 pesticides was 97.9 +/- 5.5%. Recoveries from whole blood were comparable to recoveries from plasma. This indicates that the preparation of plasma is unnecessary for the quantification of organochlorine pesticides in blood. This approach is particularly useful as a nonlethal approach for monitoring pesticide contamination in small animals for which the volume of blood is limiting.

Determination of DiazaCon in quail feed and quail serum by ion pair reversed-phase chromatography

Liquid chromatographic (LC) methods were developed for quantitating the potential avian contraceptive DiazaCon in quail feed and serum. DiazaCon was extracted from ground quail feed with basic n-butyl chloride. The n-butyl chloride extract was evaporated to dryness. The DiazaCon residues were dissolved in an aqueous methanolic ion pairing solution and quantitated by LC at 206 nm. Avian sera was combined with an equal volume of a pH 4 aqueous solution of ion pairing reagent and filtered to remove interfering proteins. DiazaCon was quantitated by LC. Mean recoveries for 500 and 2000 ppm fortified feed were 89.1 and 91.0%, respectively. The mean recovery for sera fortified at 5 levels ranging from 35 to 2000 ppm was 84.9%. Method limits of detection were approximately 14 and 13 ppm for feed and sera, respectively.

A prospective study of back belts for prevention of back pain and injury

CONTEXT

Despite scientific uncertainties about effectiveness, wearing back belts in the hopes of preventing costly and disabling low back injury in employees is becoming common in the workplace.

OBJECTIVE

To evaluate the effectiveness of using back belts in reducing back injury claims and low back pain.

DESIGN AND SETTING

Prospective cohort study. From April 1996 through April 1998, we identified material-handling employees in 160 new retail merchandise stores (89 required back belt use; 71 had voluntary back belt use) in 30 states (from New Hampshire to Michigan in the north and from Florida to Texas in the south); data collection ended December 1998, median follow-up was 6(1/2) months.

PARTICIPANTS

A referred sample of 13,873 material handling employees provided 9377 baseline interviews and 6311 (67%) follow-up interviews; 206 (1.4%) refused baseline interview.

MAIN OUTCOME MEASURES

Incidence rate of material-handling back injury workers' compensation claims and 6-month incidence rate of self-reported low back pain.

RESULTS

Neither frequent back belt use nor a belt-requirement store policy was significantly associated with back injury claim rates or self-reported back pain. Rate ratios comparing back injury claims of those who reported wearing back belts usually every day and once or twice a week vs those who reported wearing belts never or once or twice a month were 1.22 (95% confidence interval [CI], 0.87-1.70) and 0.95 (95% CI, 0.56-1.59), respectively. The respective odds ratios for low back pain incidence were 0.97 (95% CI, 0.83-1.13) and 0.92 (95% CI, 0.73-1.16).

CONCLUSIONS

In the largest prospective cohort study of back belt use, adjusted for multiple individual risk factors, neither frequent back belt use nor a store policy that required belt use was associated with reduced incidence of back injury claims or low back pain. JAMA. 2000;284:2727-2732.

A novel nemaline myopathy in the Amish caused by a mutation in troponin T1

The nemaline myopathies are characterized by weakness and eosinophilic, rodlike (nemaline) inclusions in muscle fibers. Amish nemaline myopathy is a form of nemaline myopathy common among the Old Order Amish. In the first months of life, affected infants have tremors with hypotonia and mild contractures of the shoulders and hips. Progressive worsening of the proximal contractures, weakness, and a pectus carinatum deformity develop before the children die of respiratory insufficiency, usually in the second year. The disorder has an incidence of approximately 1 in 500 among the Amish, and it is inherited in an autosomal recessive pattern. Using a genealogy database, automated pedigree software, and linkage analysis of DNA samples from four sibships, we identified an approximately 2-cM interval on chromosome 19q13.4 that was homozygous in all affected individuals. The gene for the sarcomeric thin-filament protein, slow skeletal muscle troponin T (TNNT1), maps to this interval and was sequenced. We identified a stop codon in exon 11, predicted to truncate the protein at amino acid 179, which segregates with the disease. We conclude that Amish nemaline myopathy is a distinct, heritable, myopathic disorder caused by a mutation in TNNT1.

Determination of whole-body rotenone residues in the brown tree snake (Boiga irregularis)

The brown tree snake (Boiga irregularis) is an introduced pest in Guam, responsible for extensive agricultural damage, the extinction of several bird species, and severe and frequent electrical power outages. Rotenone, a naturally occurring pesticide, has been investigated as a possible chemical control agent. An analytical method was developed to assess whole body rotenone residues ranging in concentration from 0.035 to 250 microg g(-)(1) in snakes. The method employed ethyl acetate extraction of 2 g samples of cryogenically frozen, pulverized snakes, followed by silica and Florisil solid-phase extraction cleanup. Extract analysis was performed using a high-performance liquid chromatography system employing a cyanopropyl analytical column. Tissues fortified to concentrations of 0.035, 4.82, and 250 microg g(-)(1) yielded analyte recoveries of 85.1, 85.6, and 83.5%, respectively. The linear response of rotenone standard solutions was assessed from 0. 025 to 0.25 microg mL(-)(1) (r(2) = 0.9968) and from 0.250 to 125 microg mL(-)(1) (r(2) = 0.9999). The method was simple, rugged, and reliable.

Development and testing of seven new synthetic coyote attractants

Available evidence indicates that effective coyote attractants are blends of volatile substances. Typically, attractants are a combination of biological substances such as fermented glandular materials, urines, and rotted meats. Although effective, these attractants have several distinct disadvantages. Among these is the possibility that they are unnecessarily complex and variable and, thus, difficult to replicate from one batch to the next. Although attractants containing a few reagent grade materials are available, the chemicals selected and their concentrations are not derived from actual attractants. For this reason, commercially available coyote attractants were analyzed with the intention of developing relatively simple synthetic alternatives. Purge and trap headspace analysis with gas chromatography/mass selective detection was employed to identify the volatile components of known conventional and synthetic attractants. All identified compounds were grouped according to chemical functionality, and one compound from each functional group was chosen to represent the group. Using only these representative compounds, seven synthetic attractants were formulated. Bioassays with captive coyotes (Canis latrans) were conducted to compare behavioral responses elicited by the seven new attractants, a currently available synthetic attractant, and a control. The results indicated that the attractants elicited significantly different behavioral profiles.

Expanded analysis of injury mortality among unionized construction workers

BACKGROUND

To evaluate the utility of expanding the number and precision of injury categories used in previous occupational mortality studies, this study reanalyzed data from four previous studies of unionized construction workers (construction laborers, ironworkers, sheet metal workers, and operating engineers), by expanding the number of injury categories from 6 to 33.

METHODS

Proportionate mortality ratios (PMRs) were computed using the distribution of deaths from the National Occupational Mortality Surveillance System, a mortality surveillance system from 28 states, as a comparison. A blue collar comparison group was also used in additional analyses to adjust for socioeconomic and other factors.

RESULTS

This reanalysis identified significantly elevated PMRs in at least one of the four worker groups for falls, motor vehicle crashes, machinery incidents, electrocutions, being struck by falling objects, being struck by flying objects, explosions, suffocation, and water transport incidents. Limiting the comparison population to deaths among blue collar workers did not change the results substantially.

CONCLUSIONS

This study demonstrates that increasing the precision of categories of death from injury routinely used in mortality studies will provide improved information to guide prevention. Am. J. Ind. Med. 37:364-373, 2000. Published 2000 Wiley-Liss, Inc.

Fatal occupational injuries associated with forklifts, United States, 1980-1994

BACKGROUND

This paper describes deaths of American workers involving forklifts during the 15-year period from January 1, 1980 to December 31, 1994.

METHODS

Death certificate data were obtained from the National Institute for Occupational Safety and Health's (NIOSH's) National Traumatic Occupational Fatality (NTOF) surveillance system. The narrative fields on the death certificate were searched for keywords indicating that a powered industrial vehicle (PIV) or forklift was involved in the death. This study examined the circumstances of the forklift-related deaths, the nature of the injury, and the decedent's age, gender, race, occupation, and industry. Average annual employment data from the Bureau of the Census were used to calculate civilian fatality rates by age, gender, industry, and occupation.

RESULTS

A total of 1,021 deaths were identified. The average age of the fatally injured worker was 38 years; the 1,021 forklift-related deaths resulted in a total of 27,505 years of productive life lost. The three most common circumstances of the fatalities were forklift overturns (22%), pedestrian struck by forklifts (20%), and worker crushed by forklift (16%). The greatest proportion of the fatalities (37%) occurred to workers in Manufacturing, followed by Transportation, Communication, and Public Utilities, (TCPU), (17%), Construction (16%), Wholesale Trade (8%), and Agriculture, Forestry, and Fishing (AFF) (7%). The highest forklift-related fatality rates per ten million workers occurred among transport operatives (34.0) and laborers (32.0).

CONCLUSIONS

Many of the fatalities resulting from forklift "overturns" might have been prevented if the operator had been restrained with a lap/shoulder belt. Careful consideration should be given to separating pedestrian and forklift traffic, and restricting the use of forklifts near time clocks, exits, and other areas where large numbers of pedestrians pass through an area in a short time. Additionally, systematic traffic control, including rules for pedestrian and forklift traffic, will be necessary to reduce the enormous injury and death toll associated with forklifts. Am. J. Ind. Med. 36:504-512, 1999. Published 1999 Wiley-Liss, Inc.

Determination of propionylpromazine hydrochloride in formulation matrixes using reversed-phase ion-pair small bore liquid chromatography

Propionylpromazine hydrochloride (PPZHCl) has been investigated for use with leghold traps to reduce the amount of self-inflicted trauma experienced by animals restrained by these traps. Three types of PPZHCl formulations made with Karo dark syrup, K-Y Jelly, and Vaseline were used in 2 types of tranquilizer trap devices (TTDs). A reversed-phase ion-pair liquid chromatography (LC) method using a small bore C18 column was used to: (1) determine the purity of the PPZHCl material used in these formulations, and (2) to determine the resulting PPZHCl content of each formulation. Analyte quantitation was done using UV absorption at 280 nm. Regression analysis of calibration standard solutions indicated a linear and directly proportional relationship between analyte response and PPZHCl concentration over the range evaluated. Recovery data from: (1) Vaseline formulations containing 38.8, 16.2, and 8.78% PPZHCl were 104, 92.9, and 90.2%, respectively, (2) Karo dark syrup formulations containing 26.5, 18.1, and 10.3% PPZHCl were 97.7, 99.3, and 106%, respectively, and (3) K-Y Jelly formulations containing 33.0, 23.5, and 13.4% PPZHCl were 100, 99.4, and 88.7%, respectively. The relative standard deviation (RSD) values from triplicate analysis of these formulations ranged from 0.7 to 6.7%. The PPZHCl content from 9 manufactured TTDs, 3 for each formulation type, were analyzed in triplicate and produced RSD values ranging from 0.7-6.8%. These results indicate that the formulation extraction presented could be used to evaluate the PPZHCl content in TTDs prior to field use. The use of a small bore LC column reduced the amount of solvents consumed and hazardous waste generated, compared to sample analysis that uses a more conventional analytical LC column.

Stabilization of the avicide 3-chloro-p-toluidine as the beta-cyclodextrin adduct

Stabilization of the avicide 3-chloro-p-toluidine (CPTH) on rice baits by pseudo latex polymeric coating and beta-cyclodextin inclusion was investigated. When CPTH-treated rice baits were exposed to sunlight, the CPTH formed colored compounds, which exacerbated problems with bait acceptance and efficacy. Fluidized bed coating with controlled-release polymeric psuedo latexes (RS, RL, NE) reduced CPTH loss but did not eliminate color formation. Enteric pseudo latex coatings (CAP and 4110) gave mixed results. Coating 4110 reduced CPTH loss but still allowed color formation, whereas CAP allowed more CPTH loss than any other coating as well as increased color formation. Inclusion in beta-cyclodextrin (molar ratio 1:1) led to enhanced retention of CPTH and minimal color formation. The CPT/beta-cyclodextrin adduct increased retention of CPTH from 43 to 70% upon simulated weathering. The retention was independent of the adhesives used for attachment.

Quantitation of pyrethrum residues in brown tree snakes

A reversed-phase solid-phase extraction-gas chromatography (SPE-GC)-electron capture detection method is developed to quantitate individual rethrin residues in pyrethrum-exposed brown tree snakes. Aliquots (6 g) of homogenized snake tissue are extracted with 10 mL acetonitrile. The rethrins are recovered from the acetonitrile extract and concentrated using C8 SPE. The rethrins are eluted from the SPE column with pentane, evaporated to near dryness, and reconstituted to 1 mL with 1-propanol. Individual rethrins are quantitated using GC analysis of the 1-propanol solution. Method limits of detection for rethrins range from 0.63 to 6.51 ng/g. The mean recovery for all rethrins is 70.8% with a standard deviation of 5.7%. This method is used to successfully quantitate incurred rethrin residues in pyrethrum-exposed brown tree snakes.

Reversed-phase ion-pair liquid chromatographic determination of chlorophacinone and diphacinone in steam-rolled oat baits and steam-rolled oat/wax baits

A reversed-phase ion-pair liquid chromatographic (LC) method was developed for analysis of steam-rolled oat (SRO) baits fortified with either chlorophacinone or diphacinone. Baits were prepared with and without paraffin wax. Chlorophacinone or diphacinone was extracted from wax-free SRO baits with 5 mM tetrabutylammonium phosphate methanolic ion-pairing solution. Wax baits were initially extracted with petroleum ether and then cleaned up by liquid extraction into methanolic ion-pairing solution containing 20% water. SRO extracts were analyzed with reversed-phase ion-pair LC. Chlorophacinone and diphacinone were quantified by UV absorption at 325 nm. Recoveries from SRO fortified with chlorophacinone at 25 and 150 micrograms/g were 90.7 and 90.8%, respectively, whereas for diphacinone at the same levels, recoveries were 93.5 and 92.3%, respectively. Recoveries from wax baits fortified at 25 and 75 micrograms/g chlorophacinone were 98.5 and 100%, respectively, whereas for diphacinone at the same levels, recoveries were 93.6 and 98.0%, respectively. Method limits of detection for chlorophacinone and diphacinone in SRO baits were estimated to be 1.0 and 0.76 micrograms/g, respectively. Method limits of detection for chlorophacinone and diphacinone in wax baits were estimated to be 4.2 and 2.8 micrograms/g, respectively.

Reversed-Phase Ion-Pair High-Performance Liquid Chromatographic Quantitation of Difethialone Residues in Whole-Body Rodents with Solid-Phase Extraction Cleanup

A reversed-phase ion-pair high-performance liquid chromatographic method was developed for the determination of difethialone residues in laboratory rats (Rattus norvegicus). Difethialone was extracted from rat tissue with chloroform/acetone/formic acid. The extracts were cleaned up by a solid-phase extraction (SPE) procedure using both silica and aminopropyl SPE sorbents, concentrated, and analyzed by reversed-phase ion-pair high-performance liquid chromatography. Difethialone was quantitated via ultraviolet absorbance at 262 nm. A surrogate compound, brodifacoum, was used to correct for method performance. The mean surrogate-corrected recoveries for whole ground rodent fortified at 0.2, 1.0, and 20 µg/g difethialone were 92.3 +/- 7.7, 84.8 +/- 6.6, and 90.2 +/- 3.1%, respectively. The method limit of detection was 0.054 µg/g.

Solid-phase extraction method for the quantitative analysis of organochlorine pesticides in wildlife urine

A gas chromatographic method for the analysis of nine organochlorine pesticides in wildlife urine is described. Reversed-phase solid-phase extraction is utilized to extract the organochlorine pesticides from urine. The pesticides are recovered by elution with hexane-ethyl ether (1:1) and quantified by gas chromatography with electron-capture detection. Method detection limits range from 1.4 to 2.7 micrograms/L. Mean recoveries for all pesticides are 90.6%.

Design and conduct of occupational injury intervention studies: a review of evaluation strategies

Occupational injuries continue to exact a great toll on American workers and their employers--the physical and financial costs are enormous. However, in the current political climate, few employers or regulatory agencies will implement injury prevention interventions without specific evidence of their effectiveness. This paper reviews the literature on the design, conduct, and evaluation of occupational injury interventions. Our review suggests that randomized controlled trials are rare and also notes that the quasi-experimental studies in the literature often use the weakest designs. We recommend a hierarchical approach to evaluating occupational injury interventions--beginning with qualitative studies, following up with simple quasi-experimental designs using historical controls, continuing with more elaborate quasi-experimental designs comparing different firms' experience, and, when necessary, implementing randomized controlled trials.

Two new oral chemical biomarkers for coyotes

Pentachlorobenzene (PeCB) and 1,2,3,4-tetrachlorobenzene (TeCB) were evaluated as oral chemical biomarkers when administered to coyotes (Canis latrans) during the period of 31 January to 10 August 1994. Three coyotes each received 100 mg of PeCB and three received 100 mg of TeCB, each in a mineral oil formulation. Three additional coyotes received only the mineral oil carrier. Muscle and adipose tissues, blood serum, and fecal samples were evaluated by capillary gas chromatography with electron capture detection for 120 days following administration. Residues of PeCB were detected in serum, feces, and adipose and muscle tissues for 120 days post-treatment; TeCB residues were detected in feces and serum at 1 and 8 days post-treatment and in adipose tissue at 30 days post-treatment. Residues of TeCB were not detected in muscle tissue at any point in the study.

Renal abnormalities and an altered inflammatory response in mice lacking cyclooxygenase II

Prostaglandins have wide-ranging effects in the body and are thought to be important mediators of inflammation. Cyclooxygenase (COX) plays a key regulatory role in prostaglandin synthesis, and occurs in both constitutive (COX-1) and inducible (COX-2) isoforms. COX-1 is thought to provide cytoprotective effects, whereas COX-2 is both inducible and the major isoform of inflammatory cells. Reduction of prostaglandin production by inhibition of cyclooxygenases appears to be the main mechanism of action of most non-steroidal anti-inflammatory drugs (NSAIDS). Here we present an animal model of COX-2 deficiency that was generated by gene targeting. Defects in null mice correlating with reduced viability included renal alterations, characteristic of renal dysplasia (100% penetrance), and cardiac fibrosis (50% penetrance). Female Cox-2-/- mice were infertile. COX-2 deficiency failed to alter inflammatory responses in several standard models, but striking mitigation of endotoxin-induced hepatocellular cytotoxicity was observed.

Occupational injury and stress

A literature search was conducted to identify studies that measured the relationship between stress and occupational injury. Studies that provided a quantitative measure of stress and occupational injury and a quantitative assessment of the relationship between these two factors were selected for this review. Twenty studies were identified, and all had P values of less than .05 or odds ratios ranging from .3 to 4.6. Twelve of 17 measures had odds ratios greater than 1.0. Several factors limit the generalizability of these results, however, and these include methodological differences in the assessment of stress and injury, study design, and limited representation of occupations.

Comparison of reversed-phase and ion-pair chromatography for the determination of strychnine in animal tissues

Ion-pair and reversed-phase high-performance liquid chromatography (HPLC) were evaluated for quantification of strychnine in mountain beaver tissues. Retention time shifts hindered strychnine quantification with both HPLC systems. Co-extracted free fatty acids released during storage formed ion-pairs with strychnine, resulting in increased retention by reversed-phase HPLC. Competition with co-extracted basic compounds is likely responsible for the decreased retention of strychnine by ion-pair HPLC. Following an acid-base clean-up, optimal results were obtained with reversed-phase HPLC. Ion-pair chromatography was then used for qualitative confirmation of strychnine residues.

Interleukin-8 receptor beta. The role of the carboxyl terminus in signal transduction

Two interleukin-8 (IL-8) receptors, alpha and beta, have been identified and cloned. Both receptors are thought to transduce signals by coupling to GTP-binding proteins. The aim of this study is to determine whether the carboxyl terminus (C') of IL-8 receptor beta (IL-8R beta) is involved in signaling in response to IL-8. We have constructed a number of IL-8R beta genes that encode truncated forms of the IL-8R beta. The deletions consisted of amino acids 349-355, 336-355, 325-355, and 317-355 (termed beta 2, beta 3, beta 4, and beta 5, respectively). 293 human embryonic kidney cells were transfected with the wild type IL-8R beta (beta 1) and with these mutants. Cells transfected with the mutated receptors expressed the receptors and bound IL-8 with the same high affinity as cells transfected with the wild type receptor. The capacity of the mutated receptors to convey functional signals was evaluated by comparing the chemotaxis index of cells expressing the C'-truncated receptors to the index of cells expressing the wild type receptor. The results indicate that while cells expressing beta 1, beta 2, beta 3, and beta 4 were chemoattracted in response to IL-8, cells expressing beta 5 did not migrate in response to IL-8 stimulation. Therefore, the data suggest that amino acids 317-324 are involved in signaling by IL-8R beta.

Social support for smoking cessation and abstinence: the Lung Health Study. Lung Health Study Research Group

This article evaluates the relationship of social support to smoking cessation and continued abstinence of 3923 men and women with mild to moderate airway obstruction in the Lung Health Study. At both the end of a 12-week group program and after 1 year, men but not women who were supported in quitting were more likely to be successful. Married status facilitated quitting but was less strongly related to long-term abstinence. Participants supported by an ex-smoker who had attended the group program with them were very likely not smoking after 1 year (men, 74.7%; women, 72.4%). Participants supported by a smoker were less than half as likely to have achieved abstinence after 1 year but still had cessation rates greater than 30%. The nature of these relationships has implications for the distinction between women and men in studies of social support and for intervention strategies. Support people should be included in cessation intervention programs. Spouse involvement, however, is more evidently useful for men than for women.

Effectiveness of behavioral safety belt interventions

A wide variety of approaches have been developed to promote safety belt use. This paper evaluates the relationship of types of behavioral safety belt programs to short- and long-term safety belt use rates. Five types of programs were examined: Law, Incentive, Education, Monitoring, and Prompt. Programs were generally effective in increasing use rates, with a median increase of 17.0% (95% CI = 13.4%, 20.1%). Program type differentially affected use rates, with Law and Incentive producing the highest increase in rates. Length of intervention and number of interventions within one program were not significantly related to use rates. Immediately after intervention ended, safety belt use declined but soon stabilized, with rates remaining significantly higher than baseline.

The efficacy of training for occupational injury control

Fifty years after reports that training enhances workplace safety began to appear in the literature, training continues to be considered a practical approach to injury prevention. However, data suggest that workplace training is not commonplace. Studies of the effectiveness of training are reviewed, and successful components of training programs are described.

Design and results of the initial intervention program for the Lung Health Study. The Lung Health Study Research Group

BACKGROUND

The design and results of the initial intervention program of the Lung Health Study are presented for 3,923 male and female participants. One of the major aims of this clinical trial was to achieve smoking cessation early in the study and to provide intensive follow-up procedures for maintaining abstinence. In addition, compliance with use of aerosolized inhalers (either placebo or active bronchodilator) would be necessary in order to achieve the trial goal of improved pulmonary function.

RESULTS

Eighty-eight percent of the special intervention participants attended the 4-month follow-up visit. Forty-six percent reported not smoking from quit day through the visit, and an additional 13% had stopped smoking at the end of 4 months, although they had not achieved abstinence since quit day. The aerosol inhaler compliance was self-reported at 81% at the 4-month visit. Validating the self-reports by weighing canisters reduced the "good" compliance rates to 66%.

CONCLUSIONS

The intensive behavioral program was effective in achieving high initial rates of smoking cessation and inhaler compliance. Use of nicotine gum appeared to be an effective adjunct to the multicomponent behavioral program. Smoking status does appear to be related to inhaler compliance among both men and women participants.

Structure and expression of neutrophil gelatinase cDNA. Identity with type IV collagenase from HT1080 cells

Neutrophils synthesize and store intracellularly a 92-kDa type IV collagenase (gelatinase), the primary structure of which is unknown. We designed a primer based on the highly conserved cysteine-switch region of metalloproteinases and employed the polymerase chain reaction to generate a probe of the human neutrophil gelatinase (HNG) gene. This probe was used to clone the cDNA encoding HNG by screening a chronic granulocytic leukemia cDNA library. In vitro translation of the cDNA-derived HNG mRNA yielded a major product of 78 kDa and smaller autolytically activated or degraded products, all of which were recognized by anti-HNG antibody. The HNG cDNA sequence is nearly identical to that encoding a 92-kDa gelatinase secreted by HT1080 cells. In addition, primer extension and S1 analysis reveal that the above two gelatinase transcripts have similar initiation sites. The HNG cDNA hybridized to a 2.8-kilobase mRNA from chronic granulocytic leukemia cells. HNG mRNA expression was absent from uninduced HL60 cells and from HL60 cells induced to granulocytic maturation with Me2SO. However, unlike other neutrophil secondary granule genes, HNG mRNA was detected in HL60 cells induced to monocytic maturation with 12-O-tetradecanoylphorbol 13-acetate. This suggests that the HNG gene may be subject to differential control pathways in two related but distinct hematopoietic lineages.

Correlation of messenger RNA levels with protein defects in specific granule deficiency

Neutrophil specific granule deficiency (SGD) is a rare congenital disorder of unknown cause associated with an impaired inflammatory response and an absence of neutrophil secondary granules. Reduced levels of several neutrophil proteins have led to the suggestion that the defect may lie at the level of transcription, a hypothesis that is supported by abnormally low levels of lactoferrin message in the bone marrow of two SGD patients. We have examined the level of seven granule protein RNAs in one SGD patient and have compared them with reported protein levels. We have found the RNA levels for all of these genes to be reduced in proportion to the decreased levels of their respective proteins. These data further support the hypothesis that the reduced protein levels reflect a defect in transcriptional control.