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Biomedical subjects

J B Rowe

Publications and source records attributed to J B Rowe.

At least 19 recordsLinked to original sources
PubMed2002

Active maintenance in prefrontal area 46 creates distractor-resistant memory.

How does the brain maintain information in working memory while challenged by incoming distractions? Using functional magnetic resonance imaging (fMRI), we measured human brain activity during the memory delay of a spatial working memory task with distraction. We found that, in the prefrontal cortex (PFC), the magnitude of activity sustained throughout the memory delay was significantly higher on correct trials than it was on error trials. By contrast, the magnitude of sustained activity in posterior areas did not differ between correct and error trials. The correlation of activity between posterior areas was, however, associated with correct memory performance after distraction. On the basis of these findings, we propose that memory representations gain resistance against distraction during a period of active maintenance within working memory. This may be mediated by interactions between prefrontal and posterior areas.

Adult↗
PubMed2001

Working memory for location and time: activity in prefrontal area 46 relates to selection rather than maintenance in memory.

The role of the dorsal prefrontal cortex in working memory remains controversial. Influential proposals include a role in the maintenance of domain-specific information, and the processes of executive functions on remembered information. We used event-related functional magnetic resonance imaging to demonstrate a functional dissociation within prefrontal cortex in terms of the components of complex working memory tasks. The maintenance in working memory of spatial locations and their temporal order was associated with activation of area 8 and intraparietal cortex. In contrast, the selection of one location, according to its order, was associated with a distinct frontoparietal network, including dorsolateral prefrontal area 46, ventrolateral prefrontal cortex and anterior cingulate cortex and medial parietal cortex. The different contributions of these areas to selection are considered in the light of recent electrophysiological and lesion studies. We suggest a general role of the dorsolateral prefrontal area 46 in attentional selection, including selection from within working memory.

Adult↗
PubMed2001

Imaging the mental components of a planning task.

The Tower of London task (TOL) has been widely used to assess the ability to plan. We used H(2)O(15)-positron emission tomography to isolate some of the cognitive components of the task. Ten male volunteers were scanned twice in each of six conditions. In two conditions (plan) the subjects had to plan the best solution to TOL problems. In two other conditions (plan-control) the subjects were required to generate four moves without being constrained by a goal. In plan and plan-control tasks the subjects either planned the moves and then executed them (MOVE conditions) or imagined the necessary moves (IMAGINE conditions). The plan and plan-control tasks were matched for the working memory load and "initial thinking time". A visuomotor control task and rest served as baseline conditions. Performance on the plan tasks, in contrast to the baseline conditions, was associated with activation in the dorsal prefrontal cortex, premotor and parietal cortex, and cerebellum. Performance of the plan-control tasks was associated with activation of the same areas. Contrasting the plan with the plan-control tasks revealed no residual activation in the prefrontal cortex. These data show that the activity of the dorsolateral prefrontal cortex on the TOL can be accounted for by the components of generating, selecting and/or remembering mental moves. The task of relating the moves to the goal involves a comparison with a representation of the goal in posterior association areas. We did not find evidence that activation of the dorsal prefrontal cortex is specifically related to the evaluation of a path towards a specified goal, a key component of planning.

Adult↗
PubMed2001

Antibody response in sheep following immunization with Streptococcus bovis in different adjuvants.

Recent studies have shown that immunization with Streptococcus bovis using Freund's complete adjuvant (FCA) may confer protection against lactic acidosis in sheep. The major objective of this study was to compare the antibody responses to S. bovis in a practically acceptable adjuvant (Freund's incomplete adjuvant (FIA); QuilA; dextran sulphate (Dex); Imject Alum; or Gerbu) and in FCA. Thirty-five sheep were randomly allocated to 7 treatment groups. Six groups were immunized with S. bovis in an adjuvant; the other group served as the non-immunization control. The primary immunization was administered intramuscularly on day 0. followed by a booster injection on day 28. Immunization with FCA induced the highest saliva and serum antibody responses. The saliva antibody concentrations in the FIA and QuilA groups were significantly higher than those in the Alum, Dex and Gerbu groups (p < 0.01). The serum antibody concentration in the FIA group was significantly higher than those in the QuilA, Alum. Dex and Gerbu groups (p < 0.01). Immunization enhanced the antibody level in faeces (p < 0.05), but there was no significant difference between the different adjuvant groups (p > 0.05). Seven and 14 days following booster immunization, the saliva antibody levels induced by QuilA and/or FIA were comparable with the level stimulated by FCA (p > 0.05). There was a strongly positive correlation (R2 = 0.770, p < 0.01) between the antibody concentrations in salival and serum. Compared with the controls, a higher faecal dry matter content was observed in the animals immunized with either FCA or QuilA. The change in faecal dry matter content was positively associated with the faecal antibody concentration (R2 = 0.441, p < 0.05). These results indicate that FIA and QuilA were effective at inducing high levels of antibody responses to S. bovis, and suggest that either Freund's incomplete adjuvant or QuilA may be useful for preparing a practically acceptable vaccine against lactic acidosis.

Adjuvants, Immunologic↗
PubMed2000

The prefrontal cortex: response selection or maintenance within working memory?

It is controversial whether the dorsolateral prefrontal cortex is involved in the maintenance of items in working memory or in the selection of responses. We used event-related functional magnetic resonance imaging to study the performance of a spatial working memory task by humans. We distinguished the maintenance of spatial items from the selection of an item from memory to guide a response. Selection, but not maintenance, was associated with activation of prefrontal area 46 of the dorsal lateral prefrontal cortex. In contrast, maintenance was associated with activation of prefrontal area 8 and the intraparietal cortex. The results support a role for the dorsal prefrontal cortex in the selection of representations. This accounts for the fact that this area is activated both when subjects select between items on working memory tasks and when they freely select between movements on tasks of willed action.

Animals↗
PubMed2000

Immunization with a Streptococcus bovis vaccine administered by different routes against lactic acidosis in sheep.

Streptococcus bovis is an important lactic acid bacterium in the rumen, which contributes to the development of lactic acidosis. This study was designed to test the efficacy of immunization with S. bovis primed either intramuscularly (i.m.) or intraperitoneally (i.p. ) against lactic acidosis. Forty-five wethers were allocated to three treatment groups. Two groups were injected with a S. bovis vaccine by either the i.m. or i.p. route for primary immunization; both groups were further immunized by the same route(s) (oral and/or i.m.) for boosters. The third group was not immunized (control). Antibody concentrations were measured in saliva prior to and following animals being fed a grain diet, and also in the rumen fluid, before the animals were suddenly introduced to a grain diet. The average antibody concentration in the animals of the i.m. group was higher than the i.p. group (P< 0.05). The antibody concentration in the rumen fluid of immunized sheep was higher than the control animals (P< 0.01). The difference in the rumen fluid antibody concentration between the i.m. and i.p. groups was not statistically significant (P> 0.05). In the i.m. group, there was a significantly greater feed intake, higher rumen pH, lower diarrhoea scores, and less increase in blood packed cell volume following grain feeding than in the animals of the control group. The severity of diarrhoea and the increase of blood packed cell volume in the animals of the i. p. group were also less than in the animals of the control group. The results suggest that the risk of lactic acidosis can be reduced by immunization against S. bovis, and that the immunization primed i. m. is more effective than the immunization primed i.p.

Acidosis, Lactic↗
PubMed2000

Effects of various adjuvants on efficacy of a vaccine against Streptococcus bovis and Lactobacillus spp in cattle.

OBJECTIVE: To determine efficacy of vaccines incorporating QuilA, alum, dextran combined with mineral oil, or Freund adjuvant for immunization of feedlot cattle against Streptococcus bovis and Lactobacillus spp. ANIMALS: 24 steers housed under feedlot conditions. PROCEDURE: Steers were randomly assigned to 4 experimental groups and a control group. Animals in experimental groups were inoculated on days 0 and 26 with vaccines containing Freund adjuvant (FCA), QuilA, dextran combined with mineral oil (Dex), or alum as adjuvant. Serum anti-S bovis and anti-Lactobacillus IgG concentrations were measured, along with fecal pH, ruminal fluid pH, and number of S bovis and Lactobacillus spp in ruminal fluid. RESULTS: Throughout the study, serum anti-S bovis and anti-Lactobacillus IgG concentrations for animals in the Dex, QuilA, and alum groups were similar to or significantly higher than concentrations for animals in the FCA group. Serum anti-S bovis and anti-Lactobacillus IgG concentrations were significantly increased on days 26 through 75 in all 4 experimental groups, and there was a linear relationship between anti-S bovis and anti-Lactobacillus IgG concentrations. For animals in the QuilA and Dex groups, mean pH of feces throughout the period of experiment were significantly higher and numbers of S bovis and Lactobacillus spp in ruminal fluid on day 47 were significantly lower than values for control cattle. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that immunization of feedlot steers against S bovis and Lactobacillus spp with vaccines incorporating Freund adjuvant, QuilA, dextran, or alum as an adjuvant effectively induced high, long-lasting serum anti-S bovis and anti-Lactobacillus IgG concentrations. Of the adjuvants tested, dextran may be the most effective.

Adjuvants, Immunologic↗
PubMed1999

Long-term effects of short-term provision of protein-enriched diets on resistance to nematode infection, and live-weight gain and wool growth in sheep.

Weaner sheep that had been hand-fed on diets containing increasing concentrations of protein for a 9-week period (when uninfected, or infected with Haemonchus contortus) were studied during the next 69 weeks when put on to pasture as a single, unsupplemented flock. During the 9-week period, groups of 12 sheep (six infected, six uninfected) were offered one of five iso-energetic (9.0 MJ kg(-1)) diets containing 10, 13, 16, 19 or 22% crude protein. All sheep were treated with anthelmintic at the end of the 9 weeks and then put out to pasture for 69 weeks, where they were all subject to the same environmental variables including nematode larval challenge. During the grazing period, animals that had previously received the higher protein diets consistently had higher live-weight gain and wool production, higher antibody responses to both H. contortus and Trichostrongylus colubriformis antigenic challenge in vitro, and lower faecal nematode egg counts than did the lambs previously offered the lower protein diets. Faecal egg counts of the grazing sheep that had been artificially infected with H. contortus while being hand-fed were similar to those of the uninfected sheep and there was no interaction between previous infection and dietary protein concentration. We conclude that short periods of enhanced post-weaning nutrition can have long-term and perhaps life-long effects on production.

Animals↗
PubMed1999

The impact of brain imaging technology on our understanding of motor function and dysfunction.

Brain imaging techniques have demonstrated functional specialisation of multiple areas within the motor system. They have also defined the patterns of interactions between these regions during normal motor function and in motor disorders. Functional imaging makes visible the changes in cortical activity that take place over time during motor functions, from the activations a fraction of a second before voluntary action to cortical neuronal plasticity several weeks after injury. Recently, the functional abnormalities underlying various acquired and developmental motor disorders have been described, as well as the effects of therapeutic intervention.

Brain↗
PubMed1999

Immunisation against lactic acidosis in cattle.

The present study was designed to investigate the efficacy of control of lactic acidosis by immunisation against lactic acid-producing bacteria, Streptococcus bovis and Lactobacillus. Ten steers were allocated to two treatment groups. One group was immunised with a vaccine containing S. bovis (strain Sb-5) and Lactobacillus (LB-27) cells, and the other was a non-immunised control group. The vaccine, using Freund's complete adjuvant for primary immunisation and Freund's incomplete adjuvant for boosters, was administered intramuscularly. After primary immunisation, boosters were given at 2 to 4 week intervals. Both anti- S. bovis and anti- Lactobacillus IgG levels in saliva increased significantly (P < 0.01) after the 1st booster which were lower (P < 0.05) than the IgG levels after the 2nd and 3rd boosters, but were not significantly different (P > 0.05) from the IgG levels prior to a grain challenge (after the 4th booster). There were positive correlations between the anti- S.bovis and anti- Lactobacillus IgG in serum and saliva. Compared with the control group, steers in the immunised group had higher (P < 0.05) feed intakes, lower (P < 0.05) rumen concentrations of lactate and lower numbers of S. bovis and Lactobacillus. Three of the control animals were withdrawn from the grain challenge due to their rumen pH persisting below 5.2, while only one animal in the immunised group was withdrawn. These results suggest that the risk of lactic acidosis can be reduced by immunisation against S. bovis and Lactobacillus.

Acidosis, Lactic↗
PubMed1999

Immunological cross-reactivity between the vaccine and other isolates of Streptococcus bovis and Lactobacillus.

Recent studies have showed that immunisation with Streptococcus bovis (Sb-5) and Lactobacillus (LB-27) may confer protection against lactic acidosis in sheep and cattle. The present study was designed to determine the degree of immunological cross-reactivity between Sb-5 and eight other strains of Streptococcus bovis; and between LB-27 and four other isolates of Lactobacillus. The cross-reactivity index (CRI, a low CRI indicates a high degree of immunological cross-reactivity) ranged from 7.3 to 56.1% between the strains of S. bovis (the encapsulated strains with CRIs ranging from 7.3 to 12.4%). For isolates of Lactobacillus the CRIs ranged from 11.5 to 72.2%. The results indicate that all the isolates tested have a certain degree of immunological homology with Sb-5 and LB-27, and suggest that the vaccine may cross-react with a large number of strains of S. bovis and Lactobacillus which may cause lactic acidosis. As most of the S. bovis strains in the rumen are encapsulated, the high degree of homology between Sb-5 and encapsulated S. bovis strains further suggests that the vaccine containing Sb-5 may be effective against a wide range of strains of S. bovis in sheep and cattle.

Animals↗
PubMed1999

Effects of feeding virginiamycin and sodium bicarbonate to grazing lactating dairy cows.

The effects of virginiamycin, an agent active against Gram-positive lactic acid-producing bacteria, and NaHCO3 on ruminal and fecal pH, rumen volatile fatty acid proportions, blood metabolites, and milk production and composition were assessed. This study was conducted over 28 d and involved 71 dairy cows that grazed predominantly ryegrass, oats, and clover, and that were fed 10 kg of concentrate pellets/d per head. The pellets contained (per kilogram) no dietary additive, 30 mg of virginiamycin, 20 g of NaHCO3, or 30 mg of virginiamycin and 20 g of NaHCO3 on a DM basis. Ruminal pH tended to be higher in cows fed pellets containing virginiamycin (7.0 vs. 6.9; SED = 0.16). The results of in vitro incubation of ruminal fluid with glucose found the potential for L-lactic acid accumulation in ruminal fluid to be significantly lower in cows fed virginiamycin (15.5 vs. 35.3 mmol/L; SED = 2.98). Cows fed virginiamycin had significantly higher fecal pH (6.72 vs. 6.57; SED = 0.08) and produced more milk (23.94 vs. 23.32 kg/d) and more lactose than those not fed virginiamycin. No effects of NaHCO3 on fecal pH, in vitro potential for L-lactic acid accumulation in ruminal fluid, or milk production were observed, but ruminal pH tended to be higher and ruminal acetate proportion was greater for cows fed NaHCO3. Milk fat and milk protein percentage did not differ significantly as a result of dietary treatment. These data suggest that the inclusion of virginiamycin in the diet will reduce L-lactic acid accumulation in ruminal fluid and increase fecal pH in grazing dairy cattle fed concentrate supplements.

Animal Feed↗
PubMed1998

Protein supplementation improves the performance of parasitised sheep fed a straw-based diet.

A study was made of the benefits of protein supplementation for parasitised and non-parasitised lambs. Sixty, 5-month-old crossbred wether lambs were placed in individual pens indoors for 9 weeks. Half of the animals were experimentally dosed with 1500 Haemonchus contortus larvae per head per week and were fed ad libitum and the other half were worm-free, pair-fed controls. Diets were formulated to be iso-energetic (9.0 MJ of calculated metabolisable energy per kg dry matter) with five levels of protein (10, 13, 16, 19 and 22% crude protein). These diets were based on oaten chaff, with barley, cotton-seed meal, urea and mineral mix (except for the 22% crude protein diet which did not contain barley). Dietary crude protein content increased live-weight gain, feed intake, rumen fluid ammonia-N, packed cell volume, eosinophil counts and antibody responses to H. contortus L3 antigen and decreased faecal worm egg counts significantly. Infection did not significantly affect packed cell volume of animals on diets with 16, 19 and 22% crude protein content. We conclude that extra dietary protein can prevent the adverse effects of H. contortus infection on animal production.

Ammonia↗
PubMed1998

Behavioural changes in stabled horses given nontherapeutic levels of virginiamycin.

Abnormal behaviour commonly develops in intensively managed horses. A possible cause is the change in diet occurring when the horse is stabled. An experiment was performed to examine this possibility by manipulating the diet with the feed supplement virginiamycin, as Founderguard. During 4 weeks, 18 horses were fed diets ranging from hay alone to concentrate plus hay in the ratio of 3:1. The rations of half the horses given concentrate were supplemented with Founderguard. Horses eating high concentrate rations displayed abnormal oral behaviours at a higher frequency than those eating only hay. The incidence of these behaviours was reduced when diets were supplemented with Founderguard. The drop in faecal pH of animals on concentrate diets was also reduced by Founderguard. Animals on concentrate diets had an average of 21 kg less gut fill post mortem. Dietary supplementation with virginiamycin as Founderguard apparently lessens some behavioural problems associated with management of stabled horses and the intake of grain. It may allow concentrate to be fed at higher levels than customary without adverse behavioural side effects. The suggested mechanism for the improved behaviour due to Founderguard supplementation is reduced fermentative acidosis in the hindgut.

Animal Feed↗
PubMed1996

The effect of a history of conduct disorder in adult major depression.

This paper examines the impact of a history of conduct disorder on major depression in adulthood, including its symptomatology, comorbidity and response to tricyclic antidepressants. 103 subjects with DSM-III-R major depression were assessed for DSM-III-R axis I and II comorbidity, severity of depression, social functioning, general psychiatric symptomatology, early familial environment and family psychiatric history. 18 patients (17%) had a history of conduct disorder, 32 (31%) were subthreshold, and 53 (51%) had no childhood symptoms of conduct disorder. Depressed adults with a history of conduct disorder had significantly higher lifetime alcohol and drug dependence and virtually all (17/18, 94%) met criteria for a personality disorder. Despite this, the current episode of depression did not differ in severity, symptoms or response to treatment except that those with a history of conduct disorder were more likely to be agitated when depressed. The authors conclude that a history of conduct disorder is depressed patients predicts the presence of adult personality disorders and psychoactive substance dependence. In most other ways, depressed subjects with a history of conduct disorder were similar to other subjects.

Adolescent↗
PubMed1989

Lupins and energy-yielding nutrients in ewes. II. Responses in ovulation rate in ewes to increased availability of glucose, acetate and amino acids.

An experiment, using a total of 320 Merino ewes, over two successive breeding seasons was conducted to investigate the separate effects of energy-yielding and protein-yielding nutrients on ovulation rate in sheep. The available energy-yielding or protein-yielding nutrients in the blood of sheep fed a maintenance pelleted ration were increased by either intravenous infusions of metabolites (acetate, glucose or acetate + glucose), feeding lupin grain, modification of the pattern of rumen fermentation to increase propionate production using the ionophore, lasalocid, or by feeding of ruminally undegradable protein (formaldehyde-treated casein). All treatments were given for 9 days prior to and including expected time of ovulation. Ovulation rates were measured by laparoscopy. In the first season (the 1984 experiment) when the effects of lupin grain, glucose + acetate and formaldehyde-treated casein were compared, ovulation rates were increased significantly in the group fed lupin (29%, P less than 0.001) and the group infused with glucose + acetate (24%, P less than 0.01). There was an apparent (17%) but statistically non-significant increase in the group fed casein. In comparisons between lupin grain, glucose, acetate, glucose + acetate, formaldehyde-treated casein and lasalocid in the 1985 experiment there were similar significant increases in ovulation rates in the groups fed lupin, and those infused with glucose or glucose + acetate (approximately 25%, P less than 0.001). The increase in the group infused with acetate was lower at 14% (P less than 0.05) and the increases of 7% in the groups fed casein or lasalocid were not significant.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetates↗
PubMed1988

The effect of haemonchosis and blood loss into the abomasum on digestion in sheep.

1. An experiment was conducted to determine the effect of the abomasal parasite, Haemonchus contortus, on the pattern of digestion and nutrient utilization in Merino sheep. There were three groups of sheep: infected with H. contortus (300 larvae/kg live weight) (n 5), sham-infected by transferring blood from the jugular vein to the abomasum, and uninfected (control) sheep (n 9) which were fed daily rations equal to amounts consumed by 'paired' animals in the two other treatment groups. A diet containing (g/kg): lucerne (medicago sativa) chaff 490, oat chaff 480, ground limestone 10, urea 10, and sodium chloride 10, was given in equal amounts at 3-h intervals. 2. Continuous intrarumen infusions (8 d) of chromium and ytterbium were made in order to measure the flow of digesta through the rumen, duodenum and ileum with 15NH4Cl included in the infusate for the final 3 d. The loss of blood into the gastrointestinal tract was measured using 51Cr-labelled erythrocytes and the rate of irreversible loss of plasma urea was measured with reference to a single intravenous injection of [14C]urea. Samples of rumen fluid were taken for analysis of volatile fatty acid (VFA) concentrations. 3. The infected and sham-infected sheep developed severe anaemia during the period over which digestion and metabolism measurements were made (packed cell volume 0.118 (SE 0.0042) and 0.146 (SE 0.0073) respectively). The corresponding rates of blood loss into the gastrointestinal tracts were 253 (SE 23) and 145 (SE 17) ml/d. 4. The proportions of VFA in rumen fluid were altered (P less than 0.05) in the infected group with a decrease in the ratio, acetate: propionate (control 3.28, infected 2.58, standard error of difference (SED) 0.21). There was also an increase in rumen fluid outflow rate (P less than 0.01) from 4.05 litres/d in the control group to 5.53 litres/d in the infected group (SED 0.43). Water intake was higher (P less than 0.05) in the infected than in the control animals (2.25 and 5. There was a decrease (P less than 0.05) in apparent digestion of organic 5. There was a decrease (P less than 0.05) in apparent digestion of organic matter in the forestomachs of infected sheep (0.32 compared with 0.39 in the control, SED 0.02). There was also a decrease (P less than 0.05) in the apparent digestion of organic matter across the whole digestive tract (0.65 control, 0.61 infected, SED 0.013).(ABSTRACT TRUNCATED AT 400 WORDS)

Abomasum↗