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Biomedical subjects

L A Toth

Publications and source records attributed to L A Toth.

At least 55 records · Page 3Linked to original sources
PubMed1992

Modulation of sleep by cortisone in normal and bacterially infected rabbits.

Infectious disease is known to alter both sleep patterns and hydrocortisone (cortisol) concentrations in rabbits. Moreover, the sleep-altering effects of microbial infections are likely to be mediated via endogenous immune modulators whose actions are attenuated by glucocorticoids. To evaluate the relationships between sleep and glucocorticoids during infectious disease, the effects of cortisone administration (20 mg/kg, im) on sleep were examined before and after inoculation of rabbits with Staphylococcus aureus or Escherichia coli. When administered alone, cortisone did not alter the amount of time spent in slow-wave sleep (SWS) but did reduce electroencephalographic (EEG) slow-wave amplitudes during SWS, the number of bouts of SWS and the amount of time spent in rapid-eye-movement sleep. The duration of individual bouts of SWS was increased after cortisone treatment. Bacterially infected rabbits developed biphasic changes in sleep patterns that were characterized by an initial increase and a subsequent decrease both in SWS time and in EEG slow-wave amplitudes during sleep. Cortisone treatment attenuated these effects in S. aureus-inoculated rabbits. In contrast, cortisone treatment did not alter the initial phase of enhanced sleep in E. coli-inoculated rabbits but did attenuate the subsequent sleep suppression. These data indicate that glucocorticoid administration is associated with an attenuated sleep response in bacterially inoculated rabbits.

Animals↗
PubMed1992

Serum amylase activity and calcium and magnesium concentrations in young cattle grazing fescue and Bermuda grass pastures.

The study reported here was part of a long-term investigation of the effects of genotype on growth, reproduction, and metabolism in cattle grazing common Bermuda grass and endophyte-infected fescue pastures. In June 1990, blood samples were collected from the tail vein of yearling heifers and steers (Angus [AA], Brahman [BB], and their reciprocal crosses [AB, BA], n = 97). Serum amylase activity was assayed enzymatically; serum Ca and Mg concentrations were determined by atomic absorption spectrophotometry. The effects of endophyte-infected fescue depended on genotype (P less than 0.001). In yearlings having at least 1 Angus parent (AA, AB, BA), grazing endophyte-infected fescue was associated with higher serum amylase activity than was grazing Bermuda grass. But serum amylase activities of BB yearlings consuming either forage were similar. Moreover, for either forage, substantial differences were related to genotype (P less than 0.007) and gender (P less than 0.05). Angus yearlings had higher serum amylase activity than did Brahman yearlings; AB and BA yearlings had intermediate values. Heifers had higher amylase activity than did steers. The relationship among serum values of amylase, Ca, and Mg depended on forage. Yearlings consuming endophyte-infected fescue and having at least 1 Angus parent had a moderate negative correlation between serum amylase activity and Ca concentration (r = -0.53; P less than 0.0005); that is, in calves of genotypes with increased amylase activity while consuming endophyte-infected fescue (AA, AB, BA), the higher the amylase activity, the lower the serum Ca concentration. However, in yearlings consuming Bermuda grass, serum amylase and Ca values were not correlated.(ABSTRACT TRUNCATED AT 250 WORDS)

Amylases↗
PubMed1991

Pathophysiologic correlates of experimental trypanosomiasis in rabbits.

Rabbits inoculated subcutaneously with Trypanosoma brucei brucei developed parasitemia, fever, and reduced food and water intake within 4 to 6 days postinoculation. Subsequent alterations in clinicopathologic parameters included anemia and increased circulating nucleated red blood cells, fibrinogenemia, hypertriglyceridemia, and hyperproteinemia. Transient alterations in the numbers of neutrophils and lymphocytes were detected sporadically; however, leukocytosis was not a characteristic of this chronic infectious condition in rabbits.

Anemia↗
PubMed1990

Lymphocytic leukemia and lymphosarcoma in a rabbit.

Lymphocytic leukemia and lymphosarcoma were diagnosed in a rabbit with lethargy, emaciation, and pallor. The diagnosis was made on the bases of results of hematologic analysis, cytologic evaluation of a bone marrow specimen, and histologic examination. The lymphosarcoma was identified to be of T-cell origin. Leukemia is rarely diagnosed in rabbits, although lymphosarcoma is fairly common in this species.

Animals↗
PubMed1990

Somnogenic, pyrogenic, and hematologic effects of bacterial peptidoglycan.

Bacterial infections and certain muramyl peptides elicit a variety of pathophysiological effects including increases in body temperature and slow-wave sleep. Bacterial cell wall peptidoglycan is composed of muramyl peptides. To investigate the ability of isolated bacterial cell walls to enhance slow-wave sleep, rabbits were injected intravenously with cell walls isolated from Staphylococcus aureus or with soluble peptidoglycan prepared from Neisseria gonorrhoeae. These injections increased slow-wave sleep, electroencephalographic delta-wave amplitudes, and body temperature, reduced rapid-eye-movement sleep, and induced neutrophilia and lymphopenia. The somnogenic and pyrogenic effects of S. aureus cell walls developed within 1 h and persisted throughout the recording period. Injections of N. gonorrhoeae peptidoglycan induced similar effects but of larger magnitude and shorter duration. We conclude that peptidoglycan is a bacterial component that mediates the increased sleep observed during infectious disease.

Animals↗
PubMed1990

Somnogenic, pyrogenic, and hematologic effects of experimental pasteurellosis in rabbits.

Previous work has demonstrated that intravenous inoculation of rabbits with various microorganisms induces complex time-dependent alterations in sleep as well as other pathophysiological effects typically associated with infectious disease. To evaluate the effects of bacterial challenge that more closely resembles naturally developing disease, we inoculated rabbits with Pasteurella multocida, a common pathogen of this species, using routes of administration that mimic normal routes of exposure. Biphasic sleep alterations characterized initially by enhanced slow-wave sleep and later by decreased slow-wave sleep occurred after intravenous, intramuscular, subcutaneous, or intranasal inoculation. Rapid-eye-movement sleep was inhibited for most of the 48-h period after inoculation. Inoculation by all four routes also induced fever and qualitatively similar hematologic changes. However, the magnitude and specific temporal patterns of both somnogenic changes and other pathophysiological effects varied with the route of inoculation.

Administration, Intranasal↗
PubMed1990

Physiological stabilization of rabbits after shipping.

Significant physiological variations that could influence experimental outcomes have been described in laboratory animals following shipping. The objective of the present study was to monitor a variety of physiologic parameters in rabbits after shipping, and to evaluate the time necessary for stabilization of these variables in the new environment. Data indicate that rabbits develop anorexia, hyperglycemia, neutrophilia, lymphopenia and elevated plasma cortisol concentrations immediately after shipping. Most of these effects abate within 2 days after arrival, suggesting that a minimum stabilization period of 48 hours after shipping is advisable prior to use of rabbits in experimental paradigms.

Aircraft↗
PubMed1989

Hematologic effects of exposure to three infective agents in rabbits.

Infectious disease is typically accompanied by changes in the number and types of circulating leukocytes. To examine the effects of infectious challenge on the distribution of rabbit WBC, rabbits were inoculated IV with Streptococcus pyogenes, Escherichia coli, or Candida albicans. Blood was collected prior to and every 6 to 12 hours after inoculation for 48 hours. Infectious challenge did not substantially alter total WBC counts, but did cause neutrophilia and lymphopenia for 6 to 48 hours after inoculation. Similar patterns of leukocyte distribution were observed in rabbits with naturally developing clinical problems. Thus, high total WBC counts may not be a common characteristic of acute infectious conditions in rabbits, but differential distributions of various leukocyte populations can provide useful markers of disease in this species.

Animals↗
PubMed1989

Effects of microbial challenge on sleep in rabbits.

Rabbits challenged with viable Staphylococcus aureus exhibit marked time-dependent changes in sleep patterns. To examine the generality of this observation, we monitored sleep patterns for 24 h before and for 48 h after intravenous inoculation of rabbits with Streptococcus pyogenes, Escherichia coli, or Candida albicans. All three agents produced complex time-dependent changes in sleep. Inoculation with S. pyogenes or C. albicans increased the time spent in slow-wave sleep (SWS) during h 4-20 after challenge. Electroencephalographic delta wave amplitudes (DWA) increased during h 4-8 after injection, but decreased during h 24-38 after inoculation. Altered sleep patterns were not observed when similar doses of heat-killed organisms were administered. In contrast, inoculation with E. coli produced a large increase in both SWS time and DWA for the first 2-4 h after inoculation. DWA then decreased from 6 to 32 h after inoculation. Similar effects occurred when heat-killed E. coli were administered. Rapid eye movement sleep was reduced by all three agents. These data demonstrate that altered sleep patterns occur in response to infectious challenge in rabbits, and that these changes are related to the type of infectious organism involved.

Animals↗
PubMed1989

An evaluation of distress following intraperitoneal immunization with Freund's adjuvant in mice.

Intraperitoneal immunization with Freund's adjuvant is frequently used to stimulate antibody production in mice. To evaluate the clinical and pathological effects of this technique, mice were immunized intraperitoneally with complete Freund's adjuvant and albumin, and the injection repeated 3-4 weeks later using incomplete Freund's adjuvant. This regimen induced a mean antibody titer against albumin of 1:280 within 7 days after booster immunization and increased the abdominal width, abdominal circumference and spleen weights of immunized animals. Food intake and body weight decreased after immunization, but returned to control levels within 1-2 weeks. Open-field activity was not affected. Neutrophilia, eosinophilia and monocytosis were present 7 days after immunization and persisted for the duration of the study. Gross and histopathological lesions included multiple granulomatous abdominal adhesions and lymphoid hyperplasia. Thus, intraperitoneal immunization with Freund's adjuvant and albumin produced some adverse effects in the animal (weight loss, neutrophilia and granulomatous peritonitis). However, the animals did not appear to be severely or chronically impaired, since food intake, body weight and locomotor activity were within normal limits for most of the post-immunization period.

Analysis of Variance↗
PubMed1988

Alteration of sleep in rabbits by Staphylococcus aureus infection.

Abundant evidence suggests that sleep might be altered during infectious disease, although the relationship between sleep and infectious disease has never been examined systematically. To address this issue, we determined the effects of Staphylococcus aureus infection on rabbit sleep. Rabbits inoculated intravenously with S. aureus demonstrated the expected physiological changes consistent with a state of infectious disease (e.g., lymphopenia, neutrophilia, and fever), as well as time-dependent changes in sleep patterns. The sleep changes were characterized initially by increases in (i) the time spent in slow-wave sleep, (ii) the electroencephalographic slow-wave amplitudes during slow-wave sleep, and (iii) the duration of individual bouts of slow-wave sleep. At 20 to 36 h after inoculation, sleep responses fell to levels below corresponding control values for 6 to 12 h. At 6 to 10 h after inoculation, rapid-eye-movement sleep was suppressed and remained at low levels throughout the remainder of the 48-h recording period. These effects of bacterial infection on sleep were attenuated by antibiotic (cephalothin) therapy. Inoculation with killed bacteria produced similar changes in sleep and other physiological parameters, although significantly higher numbers of organisms were required to produce equivalent responses. We postulate that changes in sleep may represent an adaptive response of the host to infectious disease.

Animals↗
PubMed1987

Factors influencing the recovery of dopamine sulfate in the assay of phenol sulfotransferase.

Phenol sulfotransferase activity is often measured by incubating dopamine with a source of the enzyme and the sulfate donor 35S-3'-phosphoadensine-5'-phosphosulfate and then separating the product, 35S-dopamine sulfate, from the substrates using precipitation with barium hydroxide and zinc sulfate. Using dopamine sulfate standards and high performance liquid chromatography with dual-electrode electrochemical detection, we investigated the effects of several parameters on product recovery obtained with this procedure. Amounts of precipitants needed to produce maximal sample-to-blank ratios were determined using crude enzyme preparations from rat brain and human platelets incubated under conditions generating approximately 3 nM dopamine sulfate. Under these conditions, recovery of 3H-DAS standards was 70-80%. Increasing either the concentration of dopamine sulfate or the amounts of precipitants used resulted in concentration-dependent decreases in dopamine sulfate recovery. These data indicate that the recovery of product in this assay may vary with assay conditions, and should be carefully monitored and optimized. Caution should be exercised when using substrates other than dopamine in this assay procedure, since similar factors might also contribute to variable recovery of other products.

Animals↗
PubMed1987

Pharmacological characterization of dopamine sulfoconjugation by human platelets.

Human platelets accumulate dopamine (DA) from the incubation medium in vitro and convert a significant percentage of the accumulated DA to dopamine sulfate (DAS). Platelet content of both DA and DAS increased linearly with incubation time and tissue concentration. Increasing the concentration of DA in the incubation medium also increased platelet content of both DA and DAS. However, after prolonged incubation times or in the presence of high concentrations of DA, the percentage conversion of DA to DAS decreased; this decrease was reversed at least partially by incubation in the presence of sodium sulfate, suggesting that sulfate availability may limit sulfoconjugation under some conditions. Incubation with fluoxetine produced a concentration-dependent decrease in both DA and DAS content of the platelets. In contrast, the agent 2,6-dichloro-4-nitrophenol, an inhibitor of the enzyme phenol sulfotransferase, did not interfere with DA uptake, but did inhibit DAS formation in a concentration-dependent manner. These studies suggest that the human platelet may represent a useful model system for the study of factors regulating DA sulfoconjugation.

Adult↗
PubMed1986

Dopamine sulfate formation and phenol sulfotransferase activity in dog and human platelets.

High performance liquid chromatography with radioactive flow detection was used to examine the accumulation and sulfoconjugation of dopamine by human and dog platelets. Platelets from both species accumulated similar amounts of dopamine from the incubation medium, but only human platelets were found to convert 3H-dopamine to 3-H-dopamine sulfate. This difference between the two species was associated with a relative absence of phenol sulfotransferase activity in dog platelets as compared to human platelets. Dog platelets did not appear to contain an inhibitor of phenol sulfotransferase activity. Despite the apparent difference in the ability of platelets to form dopamine sulfate, conc concentrations of dopamine-3-O-sulfate and dopamine-4-O-sulfate were similar in dog and human plasma. These data suggest that platelets may represent a potential source of at least some of the dopamine sulfate found in human plasma, but not in dog plasma.

Animals↗