PubMed Health⌕ Search

Biomedical subjects

J L Robertson

Publications and source records attributed to J L Robertson.

At least 19 recordsLinked to original sources
PubMed1998

Benzo[a]pyrene-induced hypocellularity of the pronephros in tilapia (Oreochromis niloticus) is accompanied by alterations in stromal and parenchymal cells and by enhanced immune cell apoptosis.

Numerous reports indicate that carcinogenic polycyclic aromatic hydrocarbons (PAH) are mammalian immunotoxicants. These environmental contaminants are widely distributed in both freshwater and costal marine ecosystems where they have been found to bioaccumulate in aquatic species, yet limited information exists regarding potential adverse effects of specific PAH on fish immune function. In the present report, Oreochromis niloticus fish (tilapia) were exposed by intraperitoneal injection to 5, 25, or 50 mg/kg of the PAH, benzo[a]pyrene (B[a]P). Histopathologic evaluation of the primary hematopoietic compartment of fish, the pronephros, demonstrated increased vacuolation of both stromal and parenchymal cells, reduction of lymphoid elements, and immune cell apoptosis. Total pronephros cell counts were diminished in a dose-dependent manner by the chemical exposure. The oxidative metabolic burst in phorbol myristate acetate (PMA)-simulated macrophages isolated from the pronephros was significantly inhibited by B[a]P, but only at the highest dose level employed. The phagocytic capacity of pronephros macrophages was not altered by the chemical treatment.

Animals↗
PubMed1998

A toxicity study of eltenac, a nonsteroidal anti-inflammatory drug, in horses.

A double-blind study was performed, in horses, to determine the potential toxic effects of the nonsteroidal anti-inflammatory drug, eltenac(4-[(2,6-dichlorophenyl) amino]-3-thiopheneacetic acid). Four treatment groups of six horses were formed. The drug was injected intravenously, once daily, at a dose level of 0.5 mg/kg, 1.5 mg/kg or 2.5 mg/kg for 15 days. A control group was injected with sterile saline solution. Horses were monitored for changes in appetite, physical examinations, biochemical evaluations and gastroscopic examinations. Complete post-mortem examinations were also performed. A few glandular gastric ulcers, mild in severity, developed in seven animals during the treatment period. This occurred more often in horses treated with high doses of eltenac (P = 0.02). A dose-dependent change of white blood cell (WBC) count and neutrophil count was noted. Total protein, albumin and globulin levels had dose-dependent decreases. One horse in the high dose group (2.5 mg/kg) developed ventral ooedema as well as hypoproteinaemia. Gross post-mortem and histological examination did not reveal any signs of drug related gastrointestinal, renal or hepatic abnormalities. Toxic effects of eltenac given intravenously were greatest in horses treated with 2.5 mg/kg of the compound for 15 days compared to other groups.

Aniline Compounds↗
PubMed1997

Interactions of recombinant and wild-type baculoviruses with classical insecticides and pyrethroid-resistant tobacco budworm (Lepidoptera: Noctuidae).

In tests with neonate Heliothis virescens (F.), we characterized interactions of all combinations of a recombinant Autographa californica (Speyer) nuclear polyhedrosis virus (AcAaIT) that expresses an insect-selective neurotoxin (AaIT) and wild-type AcNPV when combined with low concentrations of several conventional insecticides. All combinations of the recombinant virus AcAaIT and insecticides showed a positive interaction (decrease in the median lethal time (LT50) compared with the LT50 for either component alone). A type II pyrethroid (cypermethrin, which modifies currents of sodium channels) and a carbamate (methomyl, an inhibitor of acetylcholinesterase) were synergistic in combination with AcAaIT. Other insecticides also showed a positive interaction when tested in combination with the recombinant virus, but joint activity was slightly antagonistic (i.e., less than predicted activity when combined) with wild-type AcNPV. We also characterized the effectiveness of AcAaIT against pyrethroid-resistant H. virescens larvae. Our results show that a resistant strain of H. virescens is more sensitive to the recombinant virus compared with a susceptible strain. Results of these studies should be useful in planning of future field trials to increase the effectiveness of nuclear polyhedrosis viruses and to manage resistance to pyrethroids and other insecticides.

Animals↗
PubMed1997

Effects of temperature on hematologic and serum biochemical profiles of hybrid striped bass (Morone chrysops x Morone saxatilis).

OBJECTIVE: To investigate the effect of water temperature on hematologic and biochemical analytes in hybrid striped bass. ANIMALS: Hybrid striped bass (reciprocal cross: female Morone chrysops x male M saxatilis) maintained in 2,000-L tanks with undergravel filters. PROCEDURE: Fish were acclimated to 10, 18, 24, and 29 C water for 6 weeks prior to sample collection. Hematologic and serum biochemical profiles were then determined. Values were compared among the various temperatures, and with reference intervals previously determined. RESULTS: Most values were within or slightly outside the established reference intervals. The following analytes deviated notably from the reference interval: leukocyte, lymphocyte, and monocyte counts were lower than the reference intervals at 10 C; glucose values were lower at 10 and 18 C; calcium values were higher at 10 and 18 C; and total protein, albumin, globulin, and chloride values were higher at 29 C. CONCLUSION: Separate reference intervals should be developed for analytes which, because of temperature, deviate notably from the reference interval. Modifications of the established reference intervals, by including fish from varied temperatures, should allow use of one reference interval for analytes, with only slight variation attributable to temperature. CLINICAL RELEVANCE: Determining the effects of temperature on the hematologic and biochemical values helps develop clinical pathology as a diagnostic tool in fish.

Acclimatization↗
PubMed1997

Effects of ammonia and nitrate concentration on hematologic and serum biochemical profiles of hybrid striped bass (Morone chrysops x Morone saxatilis).

OBJECTIVE: To investigate the effects of poor water quality on hematologic and biochemical analytes in hybrid striped bass. ANIMALS: Hybrid striped bass (reciprocal cross: female Morone chrysops x male M saxatilis) maintained in 2,000-L tanks with undergravel filters. PROCEDURE: Fish were acclimated to high ammonia (0.15 mg/L) and nitrate (200 mg/L) concentrations for 6 weeks prior to sample collection. Hematologic and biochemical profiles were determined for these fish and for fish kept under normal conditions (control). Comparisons were made among the 3 water qualities and with reference intervals determined previously. RESULTS: Significant differences in hematologic and biochemical analytes were observed between fish in the various groups; however, most of the values were within established reference intervals. All values from fish in the high ammonia concentration tank were either within the reference interval or not significantly different from control values. Fish from the high nitrate concentration tank had higher serum creatinine values and lower chloride values than did control fish, and both analytes were substantially outside the reference intervals. CONCLUSION: High ammonia concentration of 0.15 mg/L did not affect any of the blood analytes measured. The hypercreatininemia and hypochloremia observed in fish from the 200 mg of nitrate/ml tank were considered to be pathologic changes associated with the high nitrate concentration. CLINICAL RELEVANCE: Determining the effects of water quality on hematologic and biochemical values helps to develop clinical pathology as a diagnostic tool in fish.

Alkaline Phosphatase↗
PubMed1996

The effect of temperature and water quality on antibody response to Aeromonas salmonicida in sunshine bass (Morone chrysops x Morone saxatilis).

The kinetics of the antibody response to Aeromonas salmonicida were determined in sunshine bass (hybrid striped bass: female Morone chrysops X male Morone saxatilis) acclimated to 10, 18, 24, 29 degrees C, and to 0.15 mg 1(-1) un-ionized ammonia and 200 mg 1(-1) nitrate levels. Temperature and water quality factors affected the immune response of sunshine bass. Temperatures of 10 degrees C and 18 degrees C decreased the magnitude and delayed the time of the antibody response to A. salmonicida. The antibody response was not affected at 29 degrees C, which is above the optimal temperature for sunshine bass. Elevated un-ionized ammonia concentrations of 0.15 mg 1(-1) also did not affect the antibody response. Elevated nitrate levels of 200 mg 1(-1), however, decreased the antibody response to the same extent as 18 degrees C water.

Aeromonas↗
PubMed1996

Genetic relatedness of North American populations of Tomicus piniperda (Coleoptera:Scolytidae).

We used DNA fingerprinting by random amplified polymorphic (RAPD) DNA and electrophoretic characterization of esterase isozymes to investigate the genetic relatedness of North American populations of the exotic bark beetle Tomicus piniperda (L.). Cluster analyses of genetic distances among populations identified the Illinois population as an outlier population with mean genetic distances to other populations averaging 0.895 (where complete dissimilarity = 2), compared with genetic distance averages of 0.595 among populations excluding Illinois. When genetic distance means and geographical distance between populations were compared, the results suggested that T. piniperda populations in the United States were established separately in Illinois near Lake Michigan and in Ohio along Lake Erie. Molecular markers indicated that insects derived from the 2 founder groups were interbreeding in contiguous regions in western Indiana.

Animals↗
PubMed1996

Comparison of hematologic reference intervals between culture system and type of hybrid striped bass.

OBJECTIVE: To determine and compare hematologic reference intervals for hybrid striped bass from different culture systems and for 2 types of hybrid. DESIGN: Observational comparison study. ANIMALS: Clinically normal sunshine bass (reciprocal hybrid striped bass, female Morone chrysops X male M saxatilis) raised in high-density recirculating systems, sunshine bass raised in tanks with biofilters, and palmetto bass (original hybrid striped bass, female M saxatilis X male M chrysops) raised in tanks with biofilters. PROCEDURES: Hematologic reference intervals were determined for fish from the different production systems, following the National Committee for Clinical Laboratory Standards guidelines. Reference intervals from the 3 groups were compared. RESULTS: Reference intervals were significantly different between sunshine bass in the 2 culture systems and between sunshine and palmetto bass. Many of the differences were slight, but notable differences were observed. Sunshine bass in recirculating systems had higher total leukocyte, lymphocyte, neutrophil, and monocyte counts than did either hybrid in tanks. Palmetto bass had a greater number of neutrophils than monocytes, whereas sunshine bass had more monocytes than neutrophils. Additionally, palmetto bass had a lower PCV and hemoglobin value than did either group of sunshine bass. CONCLUSIONS: Separate reference intervals should be developed for hybrid striped bass in different culture systems and for different types of hybrids. CLINICAL RELEVANCE: Determining reference intervals for hybrid striped bass provides a tool to assess the health status of these fish.

Animals↗
PubMed1996

Blood biochemical reference intervals for sunshine bass (Morone chrysops x Morone saxatilis) in three culture systems.

OBJECTIVE: To determine and compare biochemical reference intervals for sunshine bass (hybrid striped bass) from 3 culture systems. DESIGN: Observational comparison study. ANIMALS: Clinically normal sunshine bass (reciprocal hybrid striped bass, female Morone chrysops x male M saxatilis raised in high-density recirculating systems (80 g/L), low-density tanks (5 g/L) with biofilters, and cages (70 g/L) in a fresh water pond. PROCEDURE: Biochemical reference intervals were determined for fish from the different production systems following the National Committee for Clinical Laboratory Standards guidelines. Reference intervals from the 3 groups were compared. RESULTS: Reference intervals were significantly different between sunshine bass in the various culture systems. Though most of the differences in reference intervals were minor, fish in the high-density recirculating system had higher concentrations of total protein, albumin, globulin, creatinine, and phosphorus, and lower chloride values. There were no significant differences in glucose concentrations among the 3 groups of fish, and no differences in cortisol concentrations between fish in tanks and cages. CONCLUSIONS: Separate reference intervals should be developed for hybrid striped bass in different culture systems. CLINICAL RELEVANCE: Determining biochemical reference intervals for hybrid striped bass provides a tool to assess the health status of these fish.

Alkaline Phosphatase↗
PubMed1993

Plasma total and lipoprotein cholesterol, liver cholesterol and fecal cholesterol excretion in hamsters fed fiber diets.

The effect of dietary fibers on plasma lipids, liver cholesterol and fecal cholesterol excretion was investigated in hamsters. Male 9- to 11-wk-old Golden-Syrian hamsters (n = 155) were fed a purified hypercholesterolemic diet (0.1% cholesterol, 10% fat) for 5 wk to elevate plasma lipid concentrations. Sixteen animals with elevated plasma total cholesterol were randomly assigned to each treatment group: control, oat bran, guar gum, cellulose, xylan and terminal groups. After 4 wk of fiber diet consumption, the plasma total cholesterol concentrations were significantly decreased in the oat bran, guar gum and xylan groups (16, 12 and 15%, respectively) (P < 0.05). Plasma HDL cholesterol concentration was significantly decreased only in the guar gum group (12%) (P < 0.05). The combined plasma VLDL+LDL cholesterol concentrations were significantly lowered by the oat bran, xylan and cellulose diets (38, 34 and 40%, respectively) (P < 0.05). After 4 wk of control diet consumption, the liver cholesterol concentration quadrupled to 10.6 mumol cholesterol/g liver (P < 0.05). After 4 wk of consumption of the treatment diets, liver cholesterol was further increased (P < 0.05) only in the cellulose group, to 14.5 mumol cholesterol/g liver. The total fecal cholesterol excretion was the highest (P < 0.05) in the oat bran group. In the present study, oat bran, guar gum and xylan were effective hypocholesterolemic agents in hamsters.

Animals↗
PubMed1992

Investigation of glomerular lesions in dogs with acute experimentally induced Ehrlichia canis infection.

Six male Beagles were inoculated with Ehrlichia canis. Transient proteinuria was confirmed during the acute phase of infection by serial determination of urinary protein-to-creatinine ratio. Peak urine protein loss, consisting principally of albumin, was observed 2.5 to 3.5 weeks after inoculation. Renal biopsy specimens were obtained before inoculation, during peak proteinuria, and 10 weeks after inoculation when proteinuria had resolved. Renal tissue was evaluated by use of light, immunofluorescent, and electron microscopy to correlate specific glomerular lesions with development of proteinuria. Histologic examination revealed perivenular and interstitial infiltrates of lymphocytes and plasma cells localized principally to the renal cortex. Glomerular lesions were minimal to absent. Immunofluorescent staining revealed moderate to marked deposition of anti-canine IgG and IgM in the glomerular tufts and mesangium. Depositions of anti-canine complement factor C3 were not observed. Immunofluorescent staining persisted 10 weeks after inoculation, despite resolution of proteinuria, and probably represented passive trapping of immunoglobulins. Ultrastructural examination revealed fusion of podocyte processes that coincided with development of proteinuria. Electron-dense deposits or changes in the basement membrane were not observed. Morphometric measurements of average podocyte process length and percentage of coverage of basement membrane by podocyte processes were used to quantify the degree of process fusion. Both measurements increased significantly (P < 0.05) during peak proteinuria, and returned to preinoculation values when proteinuria had resolved 10 weeks after E canis inoculation. These findings indicated possible minimal-change glomerulopathy, rather than immune-complex glomerulonephritis, during acute E canis infection and could explain transient proteinuria without histologic evidence of glomerular disease.

Animals↗
PubMed1991

Hepatoencephalopathy and hypocalcemia in a miniature horse mare.

A pregnant, miniature horse mare had clinical signs of hepatoencephalopathy and concurrent hypocalcemia. The signs included dullness, inappetence, blindness, head pressing, weakness, muscle fasiculations, uveitis, and urinary incontinence. Hepatic dysfunction and hypocalcemia were confirmed by serum biochemical analysis. The mare was treated successfully with a continuous infusion of Ringer solution, calcium gluconate, dextrose, B-complex vitamins, sodium ampicillin, and flunixin meglumine; topical administration of ophthalmic ointments; and decompression of the urinary bladder. Histologic examination of a liver biopsy specimen revealed acute hepatic necrosis, which likely was associated with administration of a vaccine of equine origin 2 months earlier.

Animals↗
PubMed1991

The presence of platelet-activating factor-like activity in human spermatozoa.

Evidence is provided for the existence of platelet-activating factor (PAF)-like activity in the lipid extracts of human spermatozoa. The PAF content of human spermatozoa based on [3H]-serotonin release from washed rabbit platelets was noted to be 1.45 pmol/10(8) sperm cells in highly purified motile spermatozoa. No PAF activity was associated with the seminal fluid. Platelet-activating factor content of spermatozoa may be related to its fertility potential.

Animals↗
PubMed1991

Effect of temperature on the toxicities of ten pyrethroids to German cockroach (Dictyoptera: Blattellidae).

Of 10 pyrethroids tested by topical application of male German cockroaches, Blattella germanica (L.), d-phenothrin was the least toxic at 19, 26, or 31 degrees C. lambda-cyhalothrin was most toxic. Pyrethroids with the alpha-cyano moiety (fluvalinate, fenvalerate, cypermethrin, esfenvalerate, tralomethrin, cyfluthrin, and lambda-cyhalothrin) were more toxic than those without this functional group (d-phenothrin, resmethrin, and permethrin). At LC50, toxicity was negatively related to temperature. Temperature-toxicity responses of five of seven alpha-cyano pyrethroids were parallel, possibly indicating qualitatively identical but quantitatively different levels of detoxification enzymes.

Animals↗
PubMed1990

An examination of the influence of the epithelium on contractile responses to peptidoleukotrienes and blockade by ICI 204,219 in isolated guinea pig trachea and human intralobar airways.

The influence of the epithelium on antagonism by ICI 204,219 of contractile responses to peptide leukotriene (LT) agonists was examined in guinea pig tracheal and human bronchial rings. The -log molar KB values for ICI 204,219 were found to be independent of the epithelium in both tissues. Even though uninfluenced by the epithelium, the -log molar KB values for ICI 204,219 were about 10-fold smaller in human airways than in guinea pig trachea. Removal of the epithelium from guinea pig trachea resulted in small leftward shifts of the concentration-response curves to LTC4 and LTD4 and rightward shifts of the concentration-response curves to LTE4 when examined in the presence of indomethacin. The potentiation of LTC4 and LTD4 by epithelium removal was not seen in the presence of inhibitors of the transformation of LTC4 to LTD4 and LTD4 to LTE4. The influence of the epithelium on responses to LTE4 remained in the presence of these metabolic inhibitors. The lipoxygenase inhibitors nordihydroguaiaretic acid, B755C, Rev 5901 and AA861 antagonized responses to LTE4 in the presence, but not in the absence of epithelium. In human airways, epithelium removal resulted in a small leftward shift of the concentration-response curve to LTD4 whereas responses to LTC4 and LTE4 were unaltered. This effect was not observed in the presence of indomethacin, relating it to reduced release of cyclooxygenase products. These data suggest that contractile responses of guinea pig trachea to LTE4 are modulated by LTE4-induced release of 5-lipoxygenase product(s) only when the epithelium is present.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗