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Biomedical subjects

R D Walker

Publications and source records attributed to R D Walker.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1998

Comparison of sonicated albumin enhanced sonography to fluoroscopic and radionuclide voiding cystography for detecting vesicoureteral reflux.

PURPOSE: We compared sonicated albumin enhanced sonography to fluoroscopic and radionuclide voiding cystography for detecting vesicoureteral reflux. MATERIALS AND METHODS: After obtaining informed consent we enrolled in our study 20 patients with known or suspected vesicoureteral reflux and no contraindications to intravesical sonicated albumin. All patients underwent albumin enhanced sonography, following which 10 patients each underwent radionuclide and fluoroscopic voiding cystography. Reflux was graded by the observing radiologist and urologist. RESULTS: In 10 patients albumin enhanced sonography demonstrated reflux in 6 of the 7 (83%) ureters in which radionuclide cystography identified reflux. In 2 patients ultrasound studies were inadequate due to excessive movement during the procedure, and the patients were classified as unevaluable. In the remaining 10 patients 12 of 20 ureters (60%) were equal in the absence or presence of and degree of reflux on enhanced sonography and voiding cystourethrography. In 6 ureters voiding cystourethrography detected reflux more readily or revealed a higher grade of reflux. Two ureters had a higher reflux grade on enhanced sonography. No adverse effects were associated with intravesical sonicated albumin. CONCLUSIONS: In experienced hands sonicated albumin enhanced sonography is safe for evaluating vesicoureteral reflux. It provides the simultaneous evaluation of renal contours, parenchyma and size in addition to bladder visualization. This new technique may prove to be useful as a followup study in patients with previously documented reflux or as a primary study for sibling screening.

Adolescent↗
PubMed1997

Homozygosity and linkage-disequilibrium mapping of the urofacial (Ochoa) syndrome gene to a 1-cM interval on chromosome 10q23-q24.

The urofacial (Ochoa) syndrome (UFS) is a rare autosomal recessive disease characterized by congenital obstructive uropathy and abnormal facial expression. The patients present with enuresis, urinary-tract infection, hydronephrosis, and voiding dysfunctions as a result of neurogenic bladders. To map the UFS gene, a genome screen using a combination of homozygosity-mapping and DNA-pooling strategies was performed in 20 selected patients, one patient pool, and three control pools (unaffected relatives). After analyses of 36 randomly chosen markers, D10S677 was identified as being linked to and associated with UFS, as suggested by a significant excess of homozygosity in patients compared with that in unaffected relatives (P < 10(-6)), as well as by the allelic-frequency differences between the patient pool and control pools. Ten additional markers flanking D10S677 and covering a 22-cM region then were analyzed to fine-map the UFS gene by use of haplotype (linkage disequilibrium) analysis. All 31 patients were found to be homozygous for two closely linked markers (D10S1726 and D10S198) located approximately 5 cM telomeric to D10S677, whereas only 12% of the unaffected relatives were homozygous for both markers (P < 10(-19)). Several patients are heterozygous at two markers immediately flanking D10S1726/D10S198, one on the centromeric side (D10S1433) and the other on the telomeric side (D10S603). These recombinational events place the UFS gene near D10S1726/D10S198 and within a 1-cM interval defined by D10S1433 and D10S603 on chromosome 10q23-q24.

Chromosome Mapping↗
PubMed1997

Otitis media in preweaned Holstein dairy calves in Michigan due to Mycoplasma bovis.

Mycoplasma bovis was isolated from the tympanic bullae of dairy calves with an exudative otitis media. The history, clinical signs, gross and histologic lesions, and bacteriologic findings are described for 5 preweaned Holstein calves with otitis media from a 600-cow dairy in Michigan. Clinical findings consisted of unilateral or bilateral ear droop, epiphora, head tilt, and recumbency in severely affected calves. Postmortem examination revealed unilateral or bilateral fibrinosuppurative to caseous exudate in the tympanic bullae. Histologically, a marked fibrinosuppurative to caseous exudate filled the tympanic air spaces. The partially ulcerated tympanic mucosa was markedly thickened with mononuclear cell infiltration and proliferation of fibrous connective tissue. Bone remodeling and periosteal hyperostosis were present in some osseous septa. Mycoplasma bovis was isolated from the tympanic bullae of all 5 calves and from the lungs of 2 calves and the frontal sinus of 1 calf. Mycoplasma bovis was isolated at > 100,000 colony forming units/ml from the bulk milk tank of the farm of origin. The isolation of M. bovis from the bulk milk tank, indicating subclinical mycoplasmal mastitis coupled with the feeding of waste milk from mastitic cows to calves is suggestive of a possible source of the infection resulting in otitis media in preweaned dairy calves.

Animals↗
PubMed1997

Cloninger's tridimensional theory of personality and psychopathology: applications to substance use disorders.

OBJECTIVE: To evaluate studies that applied Cloninger's tridimensional theory of personality to substance abusers. METHODS: Medline and PsychInfo data bases were searched for studies published between 1986 and mid-1995 that used the Tridimensional Personality Questionnaire (TPQ). A supplemental manual search was conducted to identify additional evaluations of the tridimensional theory. Reports were reviewed if they included substance abusers or related tridimensional traits to substance use measures. RESULTS: Factor analyses did not consistently support the tridimensionality of the TPQ. Novelty Seeking (NS) traits distinguished alcoholics from nonalcoholics, Type B and Type 2 alcoholics from their Type A and Type 1 counterparts, smokers from nonsmokers, and individuals (substance abusers and nonabusers) with and without antisocial personality disorder (ASPD). Tridimensional traits independently predicted early onset alcohol abuse and serious delinquency in studies that did not employ the TPQ and were significantly associated with concurrent substance abuse among adolescents. Most studies that compared nonalcoholic youth with positive and negative family histories of alcoholism reported nonsignificant TPQ differences or very small effects. Few alcoholics, cigarette smokers or sons of alcoholics displayed Type 1 (low novelty seeking, high harm avoidance, high reward dependence) or Type 2 (high novelty seeking, low harm avoidance, low reward dependence) TPQ profiles, but rarely were levels of tridimensional traits determined by reference to established norms. CONCLUSIONS: NS predicts early onset alcohol abuse and criminality and discriminates alcoholics exhibiting antisocial behavior and persons with ASPD from their nonantisocial counterparts. Findings for the Harm Avoidance (HA) and Reward Dependence TPQ subscales are much less consistent. Some support for the role of elevated HA in intensity of substance use has been adduced. At present, the utility of the TPQ for prevention or clinical purposes is not well established.

Adolescent↗
PubMed1997

Evaluation of milk chocolate product as a substitute for whey in pig starter diets.

Four experiments were conducted to study the effects of substituting milk chocolate product MCP) for dried whey (DW) on growth performance of starter pigs. In Exp. 1 (4 wk) and 2 (5 wk), 440 pigs (age, 25 d) were assigned to one of four diets: 1) 0% DW + 0% MCP, 2) 20% DW + 0% MCP, 3) 10% DW + 10% MCP, or 4) 0% DW + 20% MCP. Linear reductions (P < .06) in ADG, ADFI, and gain/feed (G/ F) were detected as MCP increased. Replacement of DW with 10% MCP had little effect on ADG or ADFI in Exp. 1, but it reduced them in Exp. 2. In Exp. 3(5 wk), 192 pigs (age, 20 d) were fed one of four complex diets: 1) 15% DW + 0% MCP, 2) 10% DW + 5% MCP, 3) 5% DW + 10% MCP, or 4) 0% DW + 15% MCP. As MCP increased, ADG and ADFI decreased linearly (P < .01), but growth performance was similar between pigs fed the 0 and 5% MCP diets. Experiment 4 was a 14-d preference trial in which the four diets from Exp. 3 and 270 pigs (age, 24 d) were used to make three comparisons: a) diet 1 vs diet 2, b) diet 1 vs diet 3, and c) diet 1 vs diet 4. Pigs consumed between 65 and 77% of their total feed intake as MCP-containing diets (P < .01). In summary, MCP could replace DW at a dietary level of 5% without reducing pig performance, but MCP at dietary levels of 10% or more reduced pig performance. Pigs strongly preferred MCP over DW.

Animals↗
PubMed1996

Essential and reactive alcoholism: a review.

Methodological characteristics and substantive findings of investigations of essential and reactive alcoholics were reviewed. The data base was comprised of approximately 12 studies published between 1951-1992, most of which employed small samples of hospitalized male alcoholics. Psychometric properties of the Essential-Reactive Alcoholism Questionnaire, the instrument generally used to assess the essential-reactive dimensions, rarely were examined. The weight of the evidence suggests that essential alcoholics have earlier onset and greater severity of alcoholism, lower levels of occupational and educational achievement, more interpersonal conflict, fewer long-term friendships, more antisocial attitudes and conduct, greater density of familial alcoholism, more impaired neuropsychological functioning, and lower resting blood pressure than do reactive alcoholics. Research is needed to assess the prognostic utility of the essential-reactive typology and the degree to which the distinction may facilitate patient-treatment matching.

Alcoholism↗
PubMed1996

Characterization of Escherichia coli isolated from foals.

Serotype, biotype, antibiogram, hemolysin production, fimbrial hemagglutinins, select toxin genes (STb, STaP, LT, slt1 and slt2) and the attaching effacing (eae) gene were determined for 99 foal strains of E. coli. E. coli from diarrheic and normal foals could not be distinguished by serotype, biotype, or antibiogram. Differences (P < or = 0.05) were observed in hemolysin production (11.5% vs 0%) and the expression of mannose-resistant hemagglutinins (23% vs 13%) among E. coli from diarrheic and healthy foals, respectively. Three of the E. coli strains from diarrheic foals were positive with probes for slt genes and one was positive for STb and LT genes. One strain from a healthy foal possessed the STb gene. As determined by the polymerase chain reaction, 8 strains possessed the eae gene. Seven of the 8 strains were from diarrheic foals and one eae-positive strain was from a healthy foal. The slt-positive strains did not possess eae genes and the eae-positive strains did not possess slt genes. These results indicate that enterotoxigenic strains of E. coli are not implicated in any substantial degree in sporadic foal diarrhea. However, the identification of slt-positive and eae-positive strains in foal feces indicate the presence of potentially virulent strains among foals.

Animals↗
PubMed1996

Experimental inoculation of foals and pigs with an enterotoxigenic E. coli isolated from a foal.

Hemolytic E. coli strain 807-13, O149:NM:K88(STb+, LT+), was isolated from the feces of a neonatal diarrheic foal. E. coli 807-13 was examined for adhesion to brush border membranes (BBM) from foals, adult horses and pigs, and its pathogenicity was assessed in neonatal foals and pigs. E. coli 807-13 did not adhere to equine BBM but adhered to pig BBM. It did not cause diarrhea nor did it colonize the intestinal epithelium of 3 colostrum-deprived and 3 suckled foals challenged at 24 h of age. Acute ulcerative gastritis and acute suppurative gastritis were observed in 2 colostrum-deprived challenged foals, and acute neutrophilic enteritis was observed in 1 colostrum-deprived and in 1 suckled challenged foal. No similar histopathologic lesions were detected in the control foals. Both gnotobiotic and suckled pigs developed diarrhea after challenge exposure to E. coli 807-13 and the intestinal epithelium of the pigs was colonized. Histopathologic evidence of gastritis and enteritis among the foals indicated some complicity of E. coli 807-13 in foal enteric disease.

Animals↗
PubMed1996

Predictors of tobacco quit attempts among recovering alcoholics.

Reported here are findings from a randomized community intervention trial that followed 90 recovering alcoholic smokers for 6 months. Because the brief (10-min) study intervention had no effect on tobacco use, intervention and control participants were pooled to identify predictors of attempts to quit smoking that may inform clinical practice. During the first 6 months after discharge from residential alcohol treatment, 31% of all participants reported having quit smoking for 48 hrs or longer. Demographic and drug use history variables did not predict quit attempts, but two baseline tobacco use variables did, specifically the Fagerstrom Test for Nicotine Dependence and stage of readiness to quit smoking, p < .01. Participants with high or very high nicotine dependence scores were significantly less likely than those with moderate or low scores to attempt smoking cessation. Compared to those in precontemplation at baseline, those in the preparation stage of readiness to change were about 12 times more likely to make a serious quit attempt.

Adolescent↗
PubMed1996

Treatment of pediatric urolithiasis between 1984 and 1994.

PURPOSE: We report our experience with the management of pediatric urolithiasis during a 10-year period. Our aim was to assess the impact of new technology in the treatment of pediatric urolithiasis. MATERIALS AND METHODS: We retrospectively reviewed the records of all patients up to age 18 years in whom urolithiasis was treated from 1984 to 1994. In 37 cases 24-hour urine collections were available for metabolic evaluation. RESULTS: A total of 100 pediatric patients was treated for urolithiasis. Mean followup was 36 months. A total of 79 patients underwent 115 procedures for symptomatic urolithiasis and 21 were treated nonoperatively. In 42 patients structural anomalies of the urinary tract required additional management. Metabolic abnormalities in 48 patients included hypercalciuria in 19, defined as greater than 4 mg./kg./24 hours calcium by 24-hour urine collection. Only 24 of the 100 patients had no identifiable predisposing factors. Procedures included shock wave lithotripsy in 42 cases, basket extraction with or without ureteroscopy in 20, percutaneous nephrostolithotomy in 11 and litholapaxy in 12. Open surgery included cystolithotomy in 10 cases and other forms of open lithotomy in 15. Thus, open surgical removal was necessary in 1 of 5 cases. CONCLUSIONS: Compared to the traditional mode of stone treatment, fewer patients required open surgery. Our results indicate that a comprehensive approach to the care of pediatric patients with urolithiasis requires attention to metabolic and structural abnormalities.

Adolescent↗
PubMed1996

Management of the failed pyeloplasty.

PURPOSE: We present our experience with repeat surgery for persistent ureteropelvic junction obstruction. MATERIALS AND METHODS: We retrospectively reviewed the records of patients who underwent pyeloplasty for ureteropelvic junction obstruction between 1984 and 1994, focusing on those who underwent repeat surgery for persistent ureteropelvic junction obstruction after initial pyeloplasty. RESULTS: During the 10-year period 127 pyeloplasties were done by a single surgeon (R. D. W.). Three cases of persistent ureteropelvic junction obstruction occurred in this primary pyeloplasty series (success rate 97.6%). During the same period 9 other patients were referred to us from elsewhere for persistent ureteropelvic junction obstruction after initial pyeloplasty (total 12 patients). Ten patients underwent repeat pyeloplasty with a postoperative stent in place. Two patients needed nephrectomy at the initial repeat procedure and 1 of the 10 repeat pyeloplasty patients ultimately underwent nephrectomy. Six patients who had recurrent ureteropelvic junction obstruction were younger than 6 months at the time of the original pyeloplasty. Excessive urinary drainage was noted in 2 of our 3 cases of failed pyeloplasty. Thus, in 9 patients satisfactory resolution of obstruction was achieved by repeat pyeloplasty (salvage rate 75%). CONCLUSIONS: Persistent ureteropelvic junction obstruction is an uncommon complication after pyeloplasty. Infants who undergo pyeloplasty may be more prone to persistent obstruction after pyeloplasty. Prolonged urinary drainage seems to be a harbinger of persistent ureteropelvic junction obstruction. Careful repeat pyeloplasty with attention to preservation of the blood supply and meticulous watertight anastomosis led to satisfactory resolution of ureteropelvic junction obstruction in 75% of the cases.

Adolescent↗