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Biomedical subjects

J J Johnston

Publications and source records attributed to J J Johnston.

At least 19 recordsLinked to original sources
PubMed2006

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.

Animals↗
PubMed2006

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.

Animals↗
PubMed2005

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.

Administration, Oral↗
PubMed2004

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.

Animals↗
PubMed2004

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.

Alleles↗
PubMed2004

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.

Animals↗
PubMed2002

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.

Acetaminophen↗
PubMed2001

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.

Animals↗
PubMed2001

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.

Animals↗
PubMed2001

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.

Animals↗
PubMed2001

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.

Carcinogens↗
PubMed2001

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.

Agriculture↗
PubMed2000

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.

Adult↗
PubMed2000

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.

Amino Acid Sequence↗
PubMed2000

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.

Accidental Falls↗
PubMed2000

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.

Animals↗