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Biomedical subjects

R D Walker

Publications and source records attributed to R D Walker.

At least 19 recordsLinked to original sources
PubMed2000

Influence of upper- and lower-limb exercise training on cardiovascular function and walking distances in patients with intermittent claudication.

PURPOSE: The effects of upper-limb (arm cranking) and lower-limb (leg cranking) exercise training on walking distances in patients with intermittent claudication was assessed. METHODS: Sixty-seven patients (33 to 82 years old) with moderate to severe intermittent claudication were recruited, and the maximum power generated during incremental upper- and lower-limb ergometry tests was determined, as were pain-free and maximum walking distances (by using a shuttle walk test). Patients were randomly assigned to an upper-limb training group (n = 26) or a lower-limb training group (n = 26). An additional untrained group (n = 15) was recruited on an ad hoc basis in parallel with the main trial by using identical inclusion criteria. This group was subsequently shown to possess a similar demographic distribution to the two exercise groups. Supervised training sessions were held twice weekly for 6 weeks. RESULTS: Both training programs significantly improved the maximum power generated during the incremental upper- and lower-limb ergometry tests (P <. 001), which may reflect an increase in central cardiovascular function that was independent of the training mode. More importantly, pain-free and maximum walking distances also improved in both training groups (P <.001). The improvements in the training groups were similar; there were no changes in the untrained control group. These findings suggest that the symptomatic improvement after upper-limb exercise training may result, in part, from systemic cardiovascular effects rather than localized metabolic or hemodynamic changes. CONCLUSION: Carefully prescribed upper-limb exercise training can evoke a rapid symptomatic improvement in patients with claudication, while avoiding the physical discomfort experienced when performing lower-limb weight-bearing exercise.

Adult↗
PubMed2000

Lactational and subsequent reproductive responses of lactating sows to dietary lysine (protein) concentration.

Gilts (n = 208) were used to evaluate the effect of lysine (protein) intake over three parities on lactation and subsequent reproductive performance. Sows were assigned randomly to one of five experimental diets at each farrowing. The five corn-soybean mealbased lactation diets contained increasing concentrations of total lysine (.60, .85, 1.10, 1.35, and 1.60%) and CP (14.67, 18.15, 21.60, 25.26, and 28.82%). Other amino acids were provided at a minimum of 105% of the NRC (1988) ratio to the lysine requirement. Sows had ad libitum access to their assigned diets from parturition until weaning (19.5+/-.2 d postpartum). All sows were fed a common gestation diet (14% CP and .68% lysine) from weaning to next farrowing. Litter size was standardized by d 3 postpartum to 10 pigs in parity 1 and 11 pigs in parity 2 and 3. Increasing dietary lysine (protein) linearly decreased (P<.05) voluntary feed intake of parity 1 (from 5.4 to 4.6 kg/d), 2 (from 6.5 to 5.8 kg/d), and 3 sows (from 6.8 to 6.2 kg/d). With the increase of dietary lysine (protein) concentration during lactation, litter weight gain responded quadratically (P<.05) in all three parities. Maximal litter ADG was 2.06, 2.36, and 2.49 kg/d in parities 1, 2, and 3, respectively, which occurred at about 44, 55, and 56 g/d of lysine intake for parity 1, 2, and 3 sows, respectively. Increasing dietary lysine (protein) had no effect (P>.1) on sow weight change, weaning-to-estrus interval, and farrowing rate in all three parities and no effect on backfat change in parity 2 and 3, but tended to increase backfat loss linearly (P<.1) in parity 1. A linear decrease of second litter size (total born, from 11.7 to 10.1, P<.1; born alive, from 11.0 to 8.9, P<.01) was observed when dietary lysine (protein) increased during the first lactation. Lysine (protein) intake during the second lactation had a quadratic effect on third litter size (P<.05; total born: 13.3, 11.2, 11.6, 11.9, and 13.6; born alive: 11.8, 10.1, 10.3, 11.2, and 12.4). However, fourth litter size was not influenced by lysine (protein) intake during the third lactation. These results suggest that the lysine (protein) requirement for subsequent reproduction is not higher than that for milk production. Parity influences the lysine (protein) requirement for lactating sows and the response of subsequent litter size to previous lactation lysine (protein) intake.

Animals↗
PubMed1999

Relationships among seminal culture, seminal white blood cells, and the percentage of primary sperm abnormalities in bulls evaluated prior to the breeding season.

Semen samples from 100 beef breed bulls were evaluated for sperm morphology (phased contrast microscopy), seminal white blood cells, and the presence of potential reproductive pathogens. Eligibility required visualization of the glans penis throughout semen collection. Based on clinical spermiograms, bulls were grouped into normal, marginal, or unsatisfactory morphology classifications. The 3 experimental groups were similar in age and scrotal circumference and differed significantly in the percentage of primary sperm abnormalities. Most semen samples (94%) contained one or more potential reproductive pathogens (Hemophilus somnus. Mycoplasma bovigenitalium, Arcanobacterium pyogenes and Ureaplasma diversum). No significant relationship could be demonstrated between primary abnormalities and the assigned culture score. Our experimental results suggest that clinicians should interpret clinical semen culture results with great care. No significant relationship could be demonstrated between primary abnormalities and assigned white blood cell (WBC) score, although, only 1% of the samples was scored >5 WBC per high power field. The use of seminal WBC score may be valid adjunct to routine semen evaluation when that threshold is the basis for clinical decisions.

Actinomycetaceae↗
PubMed1999

Time-averaged mean velocity for volumetric blood flow measurements: an in vitro model validation study using physiological femoral artery flow waveforms.

This study assesses the accuracy of the volume flow measurement of the ATL HDI 3000 duplex ultrasound scanner using a model of the femoral arterial circulation. The beam profile of the transducer was measured, and used to identify regions of the beam where there may be poor insonation characteristics. The flow measurement accuracy was not found to be influenced by the vessel depth between 1.0 cm and 8.0 cm in a 0.7 cm diameter vessel. Overall accuracy was 3%+/-9%. Vessels in excess of 0.9 cm produced larger errors. In the model system, pulse rates between 60 bpm and 120 bpm had no significant effect on the measurement accuracy (p > 0.01). The results of this study suggest that accurate measurements of femoral arterial blood flow are possible. Further work will be required to assess the accuracy of the technique in vivo.

Blood Flow Velocity↗
PubMed1999

Characterization of Escherichia coli isolated from healthy dogs.

Five month old dogs from a Midwestern research kennel occasionally developed bloody diarrhea after shipment to other facilities. As previous diagnostic efforts failed to reveal any potential pathogens in feces from normal and diarrheic dogs, Escherichia coli was investigated for select virulence properties that may contribute to the occurrence of bloody diarrhea. Fecal swabs from 52 healthy dogs were examined for E. coli. Two hundred and sixty E. coli-like colonies were screened by PCR for the attaching and effacing (eae) gene, Shiga toxin (stx) genes, and the heat-stable enterotoxin type A (sta) gene. One hundred forty two of the 260 E. coli-like colonies (54.6%) from 43 dogs were eae or sta positive; and 60 of the eae and/or sta positive isolates were examined further. Among the 60 isolates, 23 (38.3%) possessed the eae gene, 32 (53.3%) possessed the sta gene, and five (8.3%) possessed both eae and sta genes (eae+/sta+). Of the 60 isolates, six sta+ and one eae+/sta+ isolates were hemolytic. When examined in the suckling mouse assay, five of six sta+ isolates and three of four eae+/sta+ isolates gave gut-to-remaining carcass ratios > or =0.083, indicating expression of heat-stable enterotoxin. These enterotoxin-producing isolates belonged to serogroups O42, O170, and O-negative.

Animals↗
PubMed1999

Inhalant use among urban American Indian youth.

AIMS: To assess the prevalence of inhalant use among urban American Indian youth and to examine differences between inhalant users and non-users. DESIGN: Baseline (T1) self-report questionnaires completed in 5th-6th grade and at seven annual follow-up assessments (T2-T8). SETTINGS: Seattle metropolitan area. PARTICIPANTS: Two hundred and twenty-four Indian youth. MEASUREMENTS: Youth-completed measures of substance use, ethnic self-identity, involvement in traditional Indian activities, family conflict, family history of alcoholism, peer and sibling deviance, self-esteem, delinquency, aggression, anxiety, depression, sensation seeking, conduct disorder and alcohol dependence. FINDINGS: Lifetime inhalant use was reported by 12.3% of adolescents. At T1, inhalant users had significantly lower perceived self-worth and average annual household incomes and significantly greater density of familial alcoholism and expression of aggressive and delinquent conduct than non-users. Aggressive behavior was the most important T1 predictor of inhalant use. Lifetime conduct and alcohol dependence disorders were 3.3 and 2.6 times more prevalent among inhalant users than non-users at T5. Inhalant users had more extensive deviant peer networks, were more sensation-seeking, and evidenced lower perceived self-worth than non-users at T8. CONCLUSIONS: Inhalant use was less prevalent in this particular sample of urban Indian adolescents than in most studies of reservation Indian youth. As with other studies of inhalant abuse, aggressive and delinquent males of low SES and low-perceived self-worth with family histories of alcohol dependence, were at highest risk for inhalant use.

Administration, Inhalation↗
PubMed1999

Latex vessels with customized compliance for use in arterial flow models.

The physical characteristics of the arterial wall exert a major influence over blood flow patterns and the pulse wave velocity is strongly affected by the elasticity of the vessel. We have developed a technique for manufacturing latex tubing which has physical characteristics similar to those of human arteries. Tubes were produced by painting a plastic rod of diameter 7 x 10(-3) m (the internal diameter of the superficial femoral artery) with liquid latex. The number of coats applied controlled the thickness, and hence the elasticity of the resulting tube. Values of compliance and pulse wave velocity were similar to those observed in vivo. The tubing was tested in a model of the femoral arterial circulation and the typical triphasic arterial now was seen. The mean flow in the vessels was also analysed, and found to be higher for the more elastic vessels, supporting existing mathematical theories and qualitative physiological data. These vessels provide a reliable method of producing physiologically accurate test segments for use in a range of arterial flow models.

Artificial Organs↗
PubMed1999

Methicillin-resistant Staphylococcus aureus outbreak in a veterinary teaching hospital: potential human-to-animal transmission.

During a 13-month period, 11 equine patients visiting a veterinary teaching hospital for various diagnostic and surgical procedures developed postprocedural infections from which methicillin (oxacillin)-resistant Staphylococcus aureus (MRSA) strains were isolated. The S. aureus isolates were identified by conventional methods that included Gram staining, tests for colonial morphology, tests for clumping factor, and tests for coagulase and urease activities and were also tested with the API STAPH IDENT system. Antimicrobial susceptibility tests were performed by the disk diffusion method. The biochemical profile and antibiogram of each isolate suggested that the isolates may have come from a common source. Because MRSA strains are very uncommon animal isolates but are rather common human isolates, a nasal swab specimen for culture was collected voluntarily from five persons associated with equine surgery and recovery in an attempt to identify a possible source of the organisms. MRSA strains were isolated from three of the five people, with one person found to be colonized with two biotypes of MRSA. The MRSA isolates from the people appeared to be identical to the isolates from horses. Further study of the isolates included SmaI and EagI macrorestriction analysis by pulsed-field gel electrophoresis conducted in two different laboratories. The results indicated that both the equine and human isolates were members of a very closely related group which appear to have originated from a common source. On the basis of the pattern associated with the infection, it is speculated that the members of the Veterinary Teaching Hospital staff were the primary source of the infection, although the specific mode of transmission is unclear.

Animals↗
PubMed1999

Effects of formalin on bacterial growth in mink feed, feed consumption and reproductive performance of adult mink, and growth of mink kits.

Feed that is typically used on commercial mink ranches is an ideal environment for bacterial growth because of the raw animal by-products used as ingredients. Recently, formaldehyde was approved for use as an antimicrobial agent in poultry feed. Experiments in our laboratory were carried out to investigate the effects of incorporating different concentrations of formalin into the feed of mink on the growth of gram-negative and gram-positive bacteria. Feed containing 0, 550 or 1100 ppm formalin was kept refrigerated for up to 7 d and the number of colony forming units of gram-negative and gram-positive bacteria derived from the feed was determined each day. Colony forming units in the formalin-treated feed were significantly fewer than colony forming units in untreated feed. In the second trial, feed containing the same concentrations of formalin was maintained at 30 C for 24 h and cultured bacterial colonies were counted at 0, 12 or 24 h of feed incubation. Both concentrations of formalin were effective in significantly reducing the number of colony forming units. A feed consumption trial determined if mink (Mustela vison) preferred formalin-treated feed to non-treated feed kept refrigerated for up to 7 d. Consumption of feed treated with 1100 ppm formalin was significantly lower than consumption of the non-treated feed on d 1, 2, 4 and 5, but body weight was not affected. A long-term feeding trial determined the effects of formalin on mink reproduction, early growth of offspring and quality of fur. Mink were fed formalin at concentrations of 0, 550 or 1100 ppm for approximately 140 d beginning 1 mo prior to mating until kits were weaned at 6 w of age. Mating success was not affected by consumption of formalin-treated diets, but kit survival at birth was adversely affected in mink consuming 1100 ppm formalin. Hemoglobin concentration, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin were significantly decreased in 6-w-old kits, but there were no significant differences in any of these parameters between the kits exposed to 0 and 550 ppm formalin. In a second phase, some kits and their dams were continued on their respective dietary treatments from weaning through pelting (approximately 220 and 320 d, respectively). At pelting, hematocrits and hemoglobin concentrations for the kits fed 1100 ppm formalin were significantly less compared to the control and 550 ppm formalin groups. There were no significant differences in body weights among female kits or adult female mink. The body weights of male kits in the 1100 ppm formalin group became significantly less than the body weights of male kits in the control and 550 ppm formalin groups as the trial progressed. The quality of fur was highest for mink in the control group and lowest for mink in the 1100 ppm formalin group. While dietary 1100 and 550 ppm formalin were effective in suppressing bacterial growth in the feed of mink, the deleterious effects of 1100 ppm formalin on kit survival, hematologic parameters, body weight, and quality of fur preclude formalin use at this concentration.

Animal Feed↗
PubMed1998

Listeriosis.

Listeria monocytogenes is ubiquitous in nature and is part of the normal flora of the distal portion of the intestinal tract of numerous animal species. Listeriosis is an emerging food borne disease that is responsible for approximately 1,700 cases of human illness each year and 650 deaths. Listeria is the cause of three main disease entities in animals and humans: neural, visceral, and reproductive. Clinical signs associated with the three forms are discussed along with diagnosis, therapy, prevention, and control.

Animals↗
PubMed1998

Effect of smoking cessation counseling on recovery from alcoholism: findings from a randomized community intervention trial.

AIMS: To assess the effects of a smoking cessation program for recovering alcoholics on use of alcohol, tobacco and illicit drugs after discharge from residential treatment. DESIGN AND SETTING: A randomized community intervention trial design was employed in which 12 residential drug treatment centers in Iowa, Kansas and Nebraska were matched and then randomly assigned to the intervention or control condition. PARTICIPANTS: Approximately 50 adult residents (inpatients) from each site were followed for 12 months after treatment discharge. INTERVENTION: Participating residents in the six intervention centers received a 4-part, individually tailored, smoking cessation program while those in the six control sites received usual care. FINDINGS: Both moderate and heavy drinking rates were reduced in the intervention group. Intervention site participants were significantly more likely than controls to report alcohol abstinence at both the 6-month (OR = 1.59, 95%CI: 1.09-2.35) and 12-month assessment (OR = 1.84, 95%CI: 1.28-2.92). Illicit drug use rates were comparable. Effect of the intervention on tobacco quit rates was not statistically significant. CONCLUSIONS: Counseling alcoholics in treatment to quit smoking does not jeopardize the alcohol recovery process. However, low-intensity tobacco interventions are unlikely to yield high tobacco quit rates.

Adult↗
PubMed1998

Evaluation of a computerized antimicrobial susceptibility system with bacteria isolated from animals.

The BIOMIC is a computerized system used to calculate the minimal inhibitory concentration (MIC) of an antimicrobial agent from a zone of inhibition generated by a disk diffusion test. This system was developed using bacterial pathogens of human origin. This study investigated the use of the BIOMIC system for determining MICs for bacterial pathogens from animals. The MICs generated by the BIOMIC system were compared with the MICs generated using a broth microdilution testing method. A total of 663 drug-organism combinations was tested. These combinations included 3 species of gram-positive bacteria, 5 species of gram-negative bacteria, and the antimicrobial agents ampicillin, gentamicin, cephalothin, ciprofloxacin, enrofloxacin, trimethoprim/sulfamethoxazole, tetracycline, and erythromycin. Overall, the MICs generated by the BIOMIC system correlated with the broth microdilution MICs for 72% of the total drug-organism combinations tested. The Pseudomonas aeruginosa strains tested showed the highest agreement between the 2 systems, with 100% for all antibacterial agents tested, whereas Pasteurella haemolytica, Pasteurella multocida, and enterococci showed the least agreement (76%, 57%, and 47%, respectively). Among these organisms, trimethoprim-sulfa showed the least agreement (31%) and ciprofloxacin showed the greatest (91%). These results indicate that the BIOMIC system could be a useful tool in veterinary medicine for producing quantitative antimicrobial susceptibility results. However, it is currently unreliable for some drug-bacteria combinations. This discrepancy possibly could be corrected by modification of the software using data points generated by a large-scale study.

Animals↗
PubMed1998

Outcome of a controlled trial of the effectiveness of intensive case management for chronic public inebriates.

OBJECTIVE: The objective of this study was to test whether an intensive case management intervention would be effective with a group of homeless chronic public inebriate clients. The primary goals of the case management were to improve the financial and residential stability of the clients and to reduce their use of alcohol. METHOD: Subjects (N = 298, 81% male) were interviewed at baseline, randomly assigned to treatment and control conditions and given follow-up interviews at 6-month intervals for 2 years. Case management services were provided for the duration of the project. Follow-up rates for the first three interviews averaged 82%. RESULTS: Repeated measures MANCOVAs showed significant group differences favoring the case-managed group in all three areas targeted by the intervention: total income from public sources, nights spent in "own place" out of the previous 60 nights and days drinking out of the previous 30 days. The results held whether the three variables were analyzed jointly or separately and for alternative measures of drinking and homelessness. Although statistically significant, the group differences are generally not large. CONCLUSIONS: The results indicate that case management had a beneficial effect on the clients receiving it. This effect may have been the result of an increase in services received by the case-managed clients.

Adult↗
PubMed1998

Recombinant bovine interleukin-2 and dry cow therapy: efficacy to cure and prevent intramammary infections, safety, and effect on gestation.

Cows from eight commercial dairies were randomly assigned to intrammamary infusions of cephapirin or cephapirin plus interleukin-2 at the end of lactation. During the first phase of the trial, interleukin-2 was administered to 159 cows at a dose of 1 mg per gland by intracisternal infusion immediately after 300 mg of cephapirin were administered. One hundred sixty-one cows received infusions of a placebo (phosphate-buffered saline; PBS) immediately after cephapirin. In the second phase of the trial, 70 cows received 2 mg of interleukin-2 per gland, and 78 cows received the placebo. Cows were observed daily by the participating farmer for 72 h after infusion and also during routine feeding and care during the dry period and at calving. Potential side effects from udder infusions, particularly gross abnormalities of the udder and signs of systemic side effects were monitored. During the first phase, cure rates for intramammary infections caused by Staphylococcus aureus that were present at the end of lactation were 33.3% for quarters treated with cephapirin and 53.6% for quarters treated with cephapirin and interleukin-2. Cure rates did not differ between treatment groups for all other pathogens or during the second phase of the trial. The incidence of new intramammary infections during the dry period was not affected by intramammary infusion of interleukin-2. Eighteen of 229 (7.9%) cows treated with interleukin-2 aborted within 49 d of treatment compared with 4 of 239 (1.7%) cows treated with PBS. Eleven of the 18 (61.1%) abortions by cows treated with interleukin-2 occurred 3 to 7 d after infusion; none of the abortions by cows treated with PBS occurred until wk 7 after infusion.

Abortion, Veterinary↗