Biomedical subjects

L L Jackson

Publications and source records attributed to L L Jackson.

At least 19 recordsLinked to original sources

PubMed2001

Epicuticular hydrocarbon variation in Drosophila mojavensis cluster species.

Epicuticular hydrocarbon variation was investigated among the three species of the Drosophila mojavensis cluster (D. mojavensis, D. arizonae, and D. navojoa) within the large D. repleta group. Because these hydrocarbons serve as contact pheromones in adult D. mojavensis, the chemical characteristics and differences in hydrocarbon profiles in populations of these three sibling species were further investigated. Twenty-seven hydrocarbon components with chain lengths ranging from C28 to C40, including n-alkanes, methyl-branched alkanes, n-alkenes, methyl-branched alkenes, and alkadienes were observed. Hydrocarbon profiles among the three species reared on different cactus hosts were easily aligned with previously identified components in D. mojavensis. Male and female D. navojoa possessed a 31-methyldotricont-6-ene absent in both D. arizonae and D. mojavensis, while lacking the 8,24-tritricontadiene present in these two species. D. navojoa adults had far less 2-methyloctacosane than these sibling species, but the significance of this difference was obscured by the degree of variation among populations in amounts of this hydrocarbon. Mainland and Baja California populations of D. mojavensis were fixed for differences in the amounts 8,24-tritricontadiene, 9,25-pentatricontadiene, and 9,27-heptatricontadiene, consistent with all previous studies. Amounts of 18 of the 27 hydrocarbon components were greater in flies reared on Opuntia cactus. Canonical discriminant function analysis resolved all three species into distinct, nonoverlapping groups, suggesting that epicuticular hydrocarbon profiles are species-specific in the D. mojavensis cluster. Based on the amounts of interpopulation variation in hydrocarbon profiles in these three species, we hypothesize that epicuticular hydrocarbon differences may evolve early during the formation of new species.

Adaptation, Physiological↗

PubMed2001

Non-fatal occupational injuries and illnesses treated in hospital emergency departments in the United States.

OBJECTIVES: To estimate the number and rate of occupational injuries and illnesses treated in hospital emergency departments and to characterize the nature, event, and source of injury and illness. SETTING: Twenty four hour emergency departments in hospitals in the United States. METHODS: Surveillance for occupational injuries and illnesses was conducted in a national probability based sample of hospital emergency departments through the National Electronic Injury Surveillance System (NEISS). Worker demographics, nature of injury and disposition, and incident circumstances were abstracted from emergency department medical records, typically within 24-72 hours of treatment. RESULTS: Approximately 3.6 million occupational injuries and illnesses were treated in emergency departments in 1998. Younger workers, particularly males, continue to have the highest rates of work related injuries. Together, lacerations, punctures, amputations, and avulsions represented one fourth of the emergency department treated injuries, mostly to hand and fingers. Sprains and strains, largely to the trunk, also accounted for one fourth of the injuries. The three leading injury events were contact with objects, bodily reactions and exertions, and falls. CONCLUSIONS: Despite apparent decreases in rates, youth continue to have a high burden of injury in the workplace. However, three fourths of all emergency department treated injuries occur to workers 20-44 years of age. Emergency department surveillance is particularly amenable to capture of young worker injuries and provides a wealth of injury details to guide prevention efforts--efforts that will likely reduce occupational injuries as these workers age. Emergency department surveillance also provides injury estimates with few demographic or employer constraints, other than the medical venue used.

Accidents, Occupational↗

PubMed1999

Analysis of the doublesex female protein in Drosophila melanogaster: role on sexual differentiation and behavior and dependence on intersex.

doublesex (dsx) is unusual among the known sex-determination genes of Drosophila melanogaster in that functional homologs are found in distantly related species. In flies, dsx occupies a position near the bottom of the sex determination hierarchy. It is expressed in male- and female-specific forms and these proteins function as sex-specific transcription factors. In the studies reported here, we have ectopically expressed the female Dsx protein (Dsx(F)) from a constitutive promoter and examined its regulatory activities independent of other upstream factors involved in female sex determination. We show that it functions as a positive regulator of female differentiation and a negative regulator of male differentiation. As predicted by the DNA-binding properties of the Dsx protein, Dsx(F) and Dsx(M) compete with each other for the regulation of target genes. In addition to directing sex-specific differentiation, Dsx(F) plays an important role in sexual behavior. Wild-type males ectopically expressing Dsx(F) are actively courted by other males. This acquisition of feminine sex appeal is likely due to the induction of female pheromones by Dsx(F). More extreme behavioral abnormalities are observed when Dsx(F) is ectopically expressed in dsx(-) XY animals; these animals are not only courted by, but also copulate with, wild-type males. Finally, we provide evidence that intersex is required for the feminizing activities of Dsx(F) and that it is not regulated by the sex-specific splicing cascade.

Animals↗

PubMed1999

Free-field audiogram of the Japanese macaque (Macaca fuscata).

The audiograms of three Japanese macaques and seven humans were determined in a free-field environment using loudspeakers. The monkeys and humans were tested using tones ranging from 8 Hz to 40 kHz and 4 Hz to 22.4 kHz, respectively. At a level of 60 dB sound pressure level the monkeys were able to hear tones extending from 28 Hz to 37 kHz with their best sensitivity of 1 dB occurring at 4 kHz. The human 60-dB hearing range extended from 31 Hz to 17.6 kHz with a best sensitivity of -10 dB at 2 and 4 kHz. These results indicate that the Japanese macaque has low-frequency hearing equal to that of humans and better than that indicated by previous audiograms obtained using headphones.

Acoustics↗

PubMed1997

Audiogram of the fox squirrel (Sciurus niger).

The behavioral audiograms of 2 fox squirrels (Sciurus niger) were determined with a conditioned avoidance procedure. The squirrels were able to hear tones ranging from 113 Hz to 49 kHz at a level of 60 dB sound-pressure level or less, with their best sensitivity of 1 dB occurring at 8 kHz. Their ability to hear frequencies below 150 Hz indicates that they have good low-frequency hearing, as do the 2 other members of the squirrel family (black-tailed and white-tailed prairie dogs) for which audiograms are available. This suggests that the ancestral sciurid may also have had good low-frequency hearing.

Animals↗

PubMed1997

Ultrasonographic pregnancy detection and inhalation anesthesia in the gray short-tailed opossum (Monodelphis domestica).

Female gray short-tailed opossums (Monodelphis domestica) with known breeding dates were anesthetized with isoflurane for ultrasonographic pregnancy detection. Beginning on gestational day 9, gravid females could be identified using a 9-MHz mechanical sector-scanning transducer equipped with a standoff pad. Fluid-filled vesicles 3 to 4 mm in diameter were seen within the thick-walled uteri on gestational days 9 and 10. Visualization revealed loss of individual vesicles, with replacement by thick, irregular uterine walls and some free luminal fluid by gestational days 12 and 13. On the basis of subsequent birth of pups, sonographic diagnosis of pregnancy was accurate in 27 of 28 oppossums examined.

Anesthesia, Inhalation↗

PubMed1996

Elimination of n-butylated hydroxytoluene methylation during fatty acid analysis by gas chromatography.

An improved method for fatty acids analysis with optimum recovery of highly polyunsaturated fatty acids methyl esters in biological systems is presented. The method is based on transesterification of phospholipid and triacylglycerols to fatty acid methyl esters using a commercially available reagent, Methyl-Prep II. Without proper precautions, as much as 50% of n-butylated hydroxytoluene (BHT) added to prevent oxidation of polyunsaturated fatty acids, could be methylated during the transesterification step. Methylated BHT elutes close to 14:0 (myristic acid) and no longer functions as an antioxidant, but the modified conditions virtually eliminate the methylation of BHT. Sample extraction and methylation was completed in 30 min at room temperature. A chelator (diethylenetriamine-pentaacetic acid; DTPA) is also added to prevent peroxidation of metal catalyzed free radical chain reactions. The standard deviations of the major fatty acids from multiple human plasma samples prepared on different days were less than 5%. The recovery of arachidonic acid, 20:4, from plasma was improved using the new method, and the recovery for docosahexaenoic acid, 22:6, spiked to human plasma was found to be 99%.

Butylated Hydroxytoluene↗

PubMed1994

Fatty acid elongation in the biosynthesis of (Z)-10-heptadecen-2-one and 2-tridecanone in ejaculatory bulb microsomes of Drosophila buzzatii.

A fatty acid chain elongation process is involved in incorporation of saturated and unsaturated fatty acyl-CoA esters into 2-tridecanone and (Z)-10-heptadecen-2-one by Drosophila buzzatii. The microsomal fraction from mature male ejaculatory bulbs is chain-length specific and requires malonyl-CoA (or acetyl-CoA, if acetyl-CoA carboxylase were present) for the chain elongation step to 2-ketones. Decarboxylation of the proposed intermediate beta-ketoacid results in 2-ketone biosynthesis. Incubation of the microsomes with the acetyl-CoA carboxylase inhibitor avidin indicated that acetyl-CoA carboxylase was present in the microsomal preparations; however, washing of the microsomal preparation removed the acetyl-CoA carboxylase activity. Fatty acyl-CoA esters were also chain elongated to produce fatty acids two and four carbons longer, suggesting that the enzymes for normal fatty acid chain elongation are also present in the microsomal fraction from ejaculatory bulbs. How much, if any, of this fatty acid chain elongation system is used for 2-ketone biosynthesis is yet to be determined.

Animals↗

PubMed1993

Tocotrienol and fatty acid composition of barley oil and their effects on lipid metabolism.

Barley oil was extracted with hexane from the grain of a high oil waxy hull-less barley. Twelve male broiler chicks were fed corn-based diets with either 10% barley oil, 10% corn oil or 10% margarine ad libitum for ten days. Total plasma cholesterol concentration of the chicks fed barley oil was 34% lower (p < 0.05) than that of the chicks fed margarine. Plasma low density lipoprotein cholesterol concentration of chicks fed barley oil was 53% and 59% lower (p < 0.05) than those of chicks fed corn oil and margarine, respectively. Plasma high density lipoprotein cholesterol and triglyceride concentration of the barley oil group were similar to those of the margarine but higher (p < 0.05) than those of the corn oil group. Chicks fed the barley oil gained more (p < 0.05) body weight than those fed the corn oil and margarine. Barley oil had an effect in suppression of TC and LDLC in chicks compared to margarine. Barley oil suppressed LDLC but not HDLC in chicks compared to corn oil. A greater weight gain of the chicks fed barley oil suggested that these chicks had normally functioning digestion and absorption. alpha-Tocotrienol and gamma-tocotrienol content of the barley oil were 24 and 17 times greater, respectively, than those observed in the corn oil, while the same fractions were not detectable in the margarine. Polyunsaturated fatty acid content of the barley oil was more than threefold that of margarine. These data suggest that alpha-tocotrienol and polyunsaturated fatty acids are hypocholesterolemic components in barley oil.

Animal Feed↗

PubMed1991

Surgical treatment of uterine torsion in a llama (Lama glama).

A multiparous llama was presented because of failure to proceed into the second stage of labor. Clockwise uterine torsion and a live fetus were identified by rectal and vaginal examinations. A cesarean operation was elected because of the prolonged first stage of labor and lack of cervical dilatation. Anesthesia was induced with a 10% guaifenesin solution administered intravenously via a pressurized pump followed by intubation and maintenance with 2% halothane. A ventral midline surgical approach exposed the uterus and the fetus was removed through a uterotomy. The placenta was manually stripped from the myometrial edges of the incision and the margins were oversewn using a continuous interlocking pattern. The uterus was then closed using a continuous Utrecht pattern and the uterus rotated 180 degrees back to its normal anatomical position. The abdomen was closed in 3 layers. Recovery of the llama was uneventful with the male cria able to nurse 6 hours post-operatively. Placental expulsion occurred approximately 48 hours after fetal removal.

Anesthesia, Intravenous↗

PubMed1989

Effects of epidural administration of xylazine or lidocaine on bovine uterine motility and perineal analgesia.

The objective of this study was to evaluate and compare the effects of caudal epidural (sacral-coccygeal interspace) administration of xylazine or lidocaine on uterine motility and perineal analgesia in the cow. Six Holstein cows (7 d post estrus) were assigned to one of three treatment groups: control (5 ml saline); lidocaine (0.2 mg/kg, 2% solution); and xylazine (0.06 mg/kg suspended in 5 ml saline), with each cow randomly assigned to each treatment over a period of three estrous cycles. Uterine motility, perineal analgesia, electrocardiography, and overt signs of sedation were recorded. Data were collected at 10-min intervals starting 10 min before treatment and continuing until 60 min post treatment. At 60 min post treatment, oxytocin (20 USP units) was administered i.v. to serve as a positive control for uterine motility. In the xylazine group, uterine motility significantly (P < 0.05) increased at 20 min post treatment, peaked at 30 min, and gradually decreased to non-significant levels at 50 min post treatment when compared with the lidocaine and control groups. Additionally, xylazine produced a higher degree and longer duration of perineal analgesia than lidocaine. Systemically, epidural xylazine produced signs of sedation, salivation, vocalization and bradycardia. Ataxia was also observed in the xylazine-treated group which may have been induced through a local and/or systemic effect. The individual properties of xylazine and lidocaine should be taken into consideration when performing an obstetrical procedure requiring the use of an epidural analgesic agent, and they should be utilized to benefit the clinician in performing the procedure.

Journal Article↗

PubMed1988

Hormonal regulation of preputial gland function in male Microtus montanus, the montane vole.

1. Preputial gland function in male Microtus montanus is androgen-dependent, both in terms of preputial weights and in the production of a series of lipids which are present in M. montanus and absent from Microtus pennsylvanicus. 2. Production of these species-typical lipids is decreased but not eliminated in castrates, as well as in adrenalectomized castrates treated with corticosterone. Therefore, in the total absence of androgens, a low level of these lipids is still produced. 3. 5 alpha-dihydrotestosterone and 17 beta-estradiol enanthate have limited effects on maintenance of preputial weight, suggesting that testosterone itself is the active steroid in the preputial gland of this species.

Adrenalectomy↗

PubMed1986

Oral pentobarbital intoxication in a bitch.

Pentobarbital intoxication in a 5-year-old female Samoyed was confirmed by the finding of a high concentration of the drug in serum. The dog apparently had consumed one of her pups, which had been euthanatized the day before with a 26% sodium pentobarbital solution. She was admitted in a condition consistent with light general anesthesia. The dog recovered after gastric lavage supportive therapy, and the administration of an alkalinizing solution to hasten drug excretion. This case demonstrates the hazards associated with indiscriminate disposal of carcasses containing large amounts of euthanasia solution.

Absorption↗

PubMed1986

Molecular cloning of mouse placental lactogen cDNA.

We have isolated a cDNA clone for the 23-kDa mouse placental lactogen II (mPL-II) from a phage lambda gt11 expression library containing cDNA synthesized from BALB/c placental RNA. Translation in vitro of placental mRNA selected by hybridization to the mPL-II cDNA clones yields a 26-kDa polypeptide that is the size of the expected precursor protein and that is immunoprecipitated with anti-mPL-II antiserum. The mPL-II cDNA clones hybridize to a 1.0-kilobase placental-specific mRNA. This mRNA, found in the fetal portion of the placenta, appears as early as day 10 of gestation and increases to a maximal level by day 12. The mPL-II cDNA nucleotide sequence has been determined. This sequence contains an open reading frame encoding a polypeptide of 222 amino acids with the amino-terminal 31 amino acids forming the signal sequence for secretion. The predicted secreted protein has 51% amino acid homology with mouse prolactin.

Amino Acid Sequence↗

PubMed1983

Phytoestrogen from Pinus ponderosa assayed by competitive binding with 17beta-estradiol to mouse uterine cytosol.

Ponderosa pine needle extracts contained a phytoestrogen that competed with 17beta-estradiol for specific binding to mouse uterine cytosol. Phytoestrogen was separated from the initial aqueous extract by acetone fractionation and eluted from a polyvinylpyrrolidone column with 90% methanol. Forty microg/ml was determined as the concentration of most purified phytoestrogen displacing 50% of 17beta-estradiol (15 pg/ml) from the estrogen specific binding sites of the mouse uterine cytosol. Intraperitoneal administration of 200 microg (0.3 g needle equivalents) of the phytoestrogen was equal in activity to 10 ng of 17beta-estradiol in a 24 hour uterine growth assay in immature mice. The phytoestrogen was retained in dialysis tubing with a 14,000 molecular weight cutoff and displayed an ultraviolet absorbance maximum at 208 nm, void of any phenolic chromophores. Phytoestrogen was being evaluated as a contributory factor in Ponderosa pine needle-induced abortion observed in range cattle.

Journal Article↗

PubMed1983

Chemical composition and biological functions of Listeria monocytogenes cell wall preparations.

A crude Listeria cell wall fraction, a purified fraction (PF) with demonstrated biological activity, as well as a third fraction of base-hydrolyzed PF (BHPF) were analyzed for chemical composition and activities not previously described. Listeria cell wall fraction and PF contained significant quantities of lipid, whereas BHPF was lipid depleted. Fatty acid compositions were typical of gram-positive bacteria. PF and BHPF were depleted in protein. Alanine, glutamic acid, diaminopimelic acid, glucosamine, and muramic acid were found in all fractions, in enhanced concentration in PF and BHPF, and with molar ratios typical of bacterial peptidoglycans. Major neutral sugars were rhamnose, ribose, ribitol, and glucose. The concentrations of rhamnose, ribose, and glucose were increased in BHPF. Differences in chemical composition of the fractions reflected differences in their biological activities: Listeria cell wall fraction induced resistance to Listeria infection, whereas PF did not. Mitogenic and adjuvant activities were demonstrated for Listeria cell wall fraction and PF but were lost in BHPF. BHPF retained the ability to induce macrophage-mediated tumoricidal activity and decrease resistance to Listeria infection.

Adjuvants, Immunologic↗

PubMed1983

Lipoteichoic acid from Listeria monocytogenes.

A lipoteichoic acid (LTA) was extracted from Listeria monocytogenes (serotype 1) by phenol-water partition and isolated by gel-filtration chromatography. The LTA exhibited amphiphilic properties by changes in gel-filtration mobility in the presence of detergent buffers and after mild base hydrolysis. In a hemagglutination assay, Listeria LTA bound antibody prepared against a known LTA from Streptococcus spp. Listeria LTA inhibited the binding of anti-LTA antibody to a Lactobacillus LTA in a hemagglutination inhibition assay. The Listeria LTA contained glucose, galactose, fatty acids, glycerol, and phosphate with molar ratios of 0.05, 0.07, 0.21, 0.94, and 1.0 to phosphate, respectively. Adjacent glycerols were linked between the C-1 and C-3 positions by phosphodiesters (structural type 1). The average chain length was 19 +/- 2 (standard deviation) glycerol-phosphate repeating units. Approximately one glycosyl side chain was present per LTA molecule. The side chain was a galactose-containing disaccharide. The lipid portion of the LTA was a galactose- and glucose-containing glycolipid which may have been a phosphoglycolipid, but the structure was not confirmed. Major fatty acids of LTA and the glycolipid were 17:anteiso, 15:anteiso, 16:iso, 16:n, and 18:n. L. monocytogenes contained cell wall products typical of gram-positive bacteria which is in contrast to the reports by others of the presence of lipopolysaccharides from L. monocytogenes.

Animals↗

PubMed1982

Pathological effects of pine needle ingestion in pregnant mice.

Consumption of Ponderosa pine (Pinus ponderosa) needles causes reproductive dysfunction in mice during early and late gestation. Consumption during early gestation results in considerable embryotoxicity which is not a result of starvation. Temporary loss of coordination and lethargy are observed in the females. Consumption of the pine needle diet results in a weight loss which persists throughout gestation. Feeding the pine needle diet from the tenth day of gestation results in spleen atrophy observable by day twelve and adrenal hypertrophy by day thirteen. The adrenal hypertrophy is characterized by an increase in the medullary component of the gland from the normal 12% medulla present on day ten to approximately 35% medulla present in the glands of those females surviving past day fourteen. Few fetal deaths are observed prior to day fifteen but the incidence of fetal death reaches 80% by day sixteen of gestation. If the dead fetuses are not aborted, maternal death follows fetal death by approximately two days; however, if the dead fetuses are aborted the females survive.

Animals↗