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Biomedical subjects

P L Roberts

Publications and source records attributed to P L Roberts.

At least 19 recordsLinked to original sources
PubMed2007

Effect of manufacturing process parameters on virus inactivation by dry heat treatment at 80 degrees C in factor VIII.

BACKGROUND AND OBJECTIVES: Dry heat treatment at 80 degrees C for 72 h is used as a virus inactivation step for some coagulation factor concentrates such as Bio Products Laboratory's (BPL) factor VIII 8Y. In the current study, the effect of this process has been tested on a range of viruses. In addition the effect of various manufacturing process parameters on virus inactivation has been investigated. MATERIALS AND METHODS: Samples of product intermediate were obtained from manufacturing, spiked with virus and subjected to freeze drying and dry heat treatment. Virus inactivation was determined by infectivity assay. RESULTS: Freeze drying followed by dry heat treatment was effective for inactivating a wide range of enveloped and nonenveloped viruses. Sucrose or protein concentration had no effect on virus inactivation. Product presentation or the interruption of heat treatment also had no effect. The inactivation of some of the viruses was greater at higher residual water content but under such conditions the stability of the product was reduced. CONCLUSION: This virus inactivation step was effective for a wide range of viruses and over the range of process conditions encountered in manufacturing. This demonstrates the robustness of this process step.

Decontamination↗
PubMed2005

Vascular pedicle ligation techniques during laparoscopic colectomy. A prospective randomized trial.

BACKGROUND: A variety of devices are available for pedicle ligation during laparoscopic colectomy including vascular staplers, clips, and electrothermal bipolar vessel-sealing devices. This study assesses their speed, reliability, and cost to guide surgeons in their choice for intracorporeal pedicle ligation. METHODS: A prospective randomized study comparing laparoscopic vascular staplers and disposable clip appliers (S/C) with the LigaSure Atlas (LIG) was performed during elective right, left, and total colectomy. Cases were stratified by procedure. Failure was defined as any bleeding after proper pedicle ligation. RESULTS: The study included 48 S/C patients and 52 LIG patients with no differences in demographics, diagnosis, procedure, number of vessels ligated per procedure, or operative time. Failure occurred for 14 (9.2%) of the 152 vessels ligated in the S/C group, as compared with 5 (3%) of the 169 vessels ligated in the LIG group (p = 0.02). The median blood loss associated with device failure was 50 ml (range, 20-50 ml) in S/C group, as compared with 100 ml (range 25-800 ml) in the LIG group (p = 0.054). Major blood loss attributable to device failure and surgeon error occurred in only one LIG case. The mean cost per case of vessel ligation was significantly less in the LIG group (317 dollars +/- 0 dollars vs 400 dollars +/- 112 dollars; p < 0.001). The cost differences were greatest for total colectomy (LIG = 317 dollars +/- 0 dollars vs S/C = 565 dollars +/- 67 dollars; p = 0.002). CONCLUSION: Device failure, although more common in the S/C group, does not result in significant blood loss. The LigaSure Atlas is more cost effective during laparoscopic colectomy, especially total colectomy, and may allow the surgeon more versatility in its application.

Adult↗
PubMed2005

Hand-assisted laparoscopic sigmoid colectomy: helping hand or hindrance?

BACKGROUND: Hand-assisted laparoscopic colectomy has been introduced as an alternative to the standard laparoscopic technique, but it has not yet been established whether it offers the same benefits. Therefore, we compared the outcome of patients undergoing hand-assisted laparoscopic sigmoid resection (HALSR) to that of those undergoing laparoscopic sigmoid resection (LSR). METHODS: The study population comprised a sequential series of consecutive patients undergoing elective laparoscopic sigmoid/left colectomy. Values are reported as mean (range). RESULTS: There were 85 LSR patients and 66 HALSR patients, with no differences in patient demographics or diagnoses. There were slight differences in operative time favoring HALSR (LSR 205 min (90-380) vs HALSR 189 min (120-290); p = 0.07), and the extraction incision was larger in the HALSR group (LSR 6.2 cm (3-25) vs HALSR 8.1 cm (7-12); p < 0.01). There was no difference in time for return of bowel function (LSR 2.8 days (1-15) vs HALSR 2.5 days (1-8); p = 0.31) or length of hospital stay (LSR 5.0 days (2-17) vs HALSR 5.2 days (3-22); p = 0.73). Complications were similar in the two groups (LSR 23% vs HALSR 21%), but there were fewer conversions in the hand-assisted group (HALSR 0% vs LSR 13%; p < 0.01). CONCLUSIONS: Hand-assisted laparoscopic sigmoid resection yields the same outcomes as standard laparoscopic techniques, but with fewer conversions. Hand-assistance is a helpful innovation that may expand the application of laparoscopic colectomy.

Adult↗
PubMed2003

Effect of manufacturing process parameters on virus inactivation by solvent-detergent treatment in a high-purity factor IX concentrate.

BACKGROUND AND OBJECTIVES: Treatment with solvent-detergent is widely used for ensuring the virus safety of plasma products. Laboratory studies have shown this procedure to be effective for inactivating enveloped viruses under manufacturing conditions. In the present study, the effect of different manufacturing process parameters on virus inactivation by treatment with polysorbate 80 and tri-n-butyl phosphate were investigated for a high-purity factor IX concentrate in order to evaluate the robustness of this step. MATERIALS AND METHODS: Samples of factor IX intermediate were obtained, virus was added and the kinetics of virus inactivation followed during incubation. The effect of altering the conditions on virus inactivation was tested. RESULTS: Solvent-detergent treatment was confirmed to effectively inactivate, i.e. by > or = 5 log, a wide range of representative enveloped viruses under standard conditions. Virus inactivation was consistently effective in a number of different manufacturing batches. Of the parameters tested, only solvent-detergent concentration and temperature significantly effected virus inactivation. CONCLUSIONS: The robustness of the solvent-detergent step for virus inactivation has been confirmed. Using the data generated, appropriate limits can be set for this manufacturing process step.

Detergents↗
PubMed2001

Patient-initiated treatment of uncomplicated recurrent urinary tract infections in young women.

BACKGROUND: Recurrent urinary tract infections (UTIs) are a common outpatient problem, resulting in frequent office visits and often requiring the use of prophylactic antimicrobial agents. Patient-initiated treatment of recurrent UTIs may decrease antimicrobial use and improve patient convenience. OBJECTIVE: To determine the safety and feasibility of patient-initiated treatment of recurrent UTIs. DESIGN: Uncontrolled, prospective clinical trial. SETTING: University-based primary health care clinic. PARTICIPANTS: Women at least 18 years of age with a history of recurrent UTIs and no recent pregnancy, hypertension, diabetes, or renal disease. INTERVENTION: After self-diagnosing UTI on the basis of symptoms, participating women initiated therapy with ofloxacin or levofloxacin. MEASUREMENTS: Accuracy of self-diagnosis determined by evidence of a definite (culture-positive) or probable (sterile pyuria and no alternative diagnosis) UTI on pretherapy urinalysis and culture. Women with a self-diagnosis of UTI that was not microbiologically confirmed were evaluated for alternative diagnoses. Post-therapy interviews and urine cultures were used to assess clinical and microbiological cure rates, adverse events, and patient satisfaction. RESULTS: 88 of 172 women self-diagnosed a total of 172 UTIs. Laboratory evaluation showed a uropathogen in 144 cases (84%), sterile pyuria in 19 cases (11%), and no pyuria or bacteriuria in 9 cases (5%). Clinical and microbiological cures occurred in 92% and 96%, respectively, of culture-confirmed episodes. No serious adverse events occurred. CONCLUSION: Adherent women can accurately self-diagnose and self-treat recurrent UTIs.

Adult↗
PubMed2001

Long-term outcomes of the ileal pouch anal anastomosis: the association of bowel function and quality of life 5 years after surgery.

INTRODUCTION: Previous studies have reported that mean health related quality of life (HRQL) levels generally attain normalcy following construction of an ileal pouch anal anastomosis (IPAA). It appears inconsistent, however, that these normal HRQL levels are achieved while bowel function (BF) scores generally remain statistically worse than "normal" (e.g., 4-8 stools/day, possible anal leakage, diaper usage). To investigate this inconsistency, the current study attempts to determine if any statistical associations are present between HRQL and BF, specifically in the long term. Multivariate regression analyses are performed using each of 8 individual HRQL domains against the full model of BF characteristics. METHODS: All patients more than 5 years status post an ileal pouch anal anastomosis (IPAA) procedure for familial adenomatous polyposis (FAP) at a single institution were studied. FAP was chosen because patients are routinely asymptomatic preoperatively. BF (e.g., stool frequency, anal leakage) and HRQL (using the 8 health domains of the SF-36) were assessed by patient interview. Student's t tests and full model multivariate regression analyses were used to analyze associations between BF and HRQL. RESULTS: The sample included 25 patients (14 male). Mean age was 39 years, mean follow-up time was 11 years. Although mean scores for the 8 individual HRQL domains were not statistically different from the general United States population, regression analyses of the different domains did demonstrate significant associations with varying levels of BF. While controlling for age and gender, the analyses show that the physical function domain is improved with the ability to pass flatus independent of stool, and physical role and mental health domains are improved with decreased stool frequency. The social function domain is improved with increased stool retention time, while the perception of general health is improved with less diaper usage and less sexual dysfunction. CONCLUSIONS: This study shows that a statistically significant association between HRQL levels and BF is present. Of the numerous BF characteristics tested, five appear to be of greater importance with regard to certain HRQL domains. This finding may have clinical implications concerning pouch construction and surgical technique. Methodologically, this study demonstrates that merely using mean levels to describe HRQL may not elucidate meaningful relationships between important clinical outcomes, such as function and HRQL.

Adenomatous Polyposis Coli↗
PubMed2000

A prospective study of asymptomatic bacteriuria in sexually active young women.

BACKGROUND: Asymptomatic bacteriuria is common in young women, but little is known about its pathogenesis, natural history, risk factors, and temporal association with symptomatic urinary tract infection. METHODS: We prospectively evaluated 796 sexually active, nonpregnant women from 18 through 40 years of age over a period of six months for the occurrence of asymptomatic bacteriuria (defined as at least 10(5) colony-forming units of urinary tract pathogens per milliliter). The women were patients at either a university student health center or a health maintenance organization. Periodic urine cultures were taken, daily diaries were kept, and regularly scheduled interviews were performed. Escherichia coli strains were tested for hemolysin, the papG genotype, and the ribosomal RNA type. RESULTS: The prevalence of asymptomatic bacteriuria (the proportion of urine cultures with bacteriuria in asymptomatic women) was 5 percent (95 percent confidence interval, 4 percent to 6 percent) among women in the university group and 6 percent (95 percent confidence interval, 5 percent to 8 percent) among women in the health-maintenance-organization group. Persistent asymptomatic bacteriuria with the same E. coli strain was rare. Symptomatic urinary tract infection developed within one week after 8 percent of occasions on which a culture showed asymptomatic bacteriuria, as compared with 1 percent of occasions when asymptomatic bacteriuria was not found (P<0.001). Asymptomatic bacteriuria was associated with the same risk factors as for symptomatic urinary tract infection, particularly the use of a diaphragm plus spermicide and sexual intercourse. CONCLUSIONS: Asymptomatic bacteriuria in young women is common but rarely persists. It is a strong predictor of subsequent symptomatic urinary tract infection.

Adolescent↗
PubMed2000

Risk factors for recurrent urinary tract infection in young women.

To define host factors associated with an increased risk of recurrent urinary tract infection (RUTI), a case-control study was conducted in 2 populations: university women and health maintenance organization enrollees. Case patients were 229 women 18-30 years old with RUTIs; control subjects were 253 randomly selected women with no RUTI history. In a multivariate model, independent risk factors for RUTI included recent 1-month intercourse frequency (odds ratio [OR], 5.8; 95% confidence interval [CI], 3.1-10.6 for 4-8 episodes), 12-month spermicide use (OR, 1.8; 95% CI, 1.1-2.9), and new sex partner during the past year (OR, 1.9; 95% CI, 1.2-3.2). Two newly identified risk factors were age at first urinary tract infection (UTI) </=15 years (OR, 3.9; 95% CI, 1.9-8.0) and UTI history in the mother (OR, 2.3; 95% CI, 1.5-3.7). Blood group and secretor phenotype were not associated with RUTI. In young women, risk factors for sporadic UTI are also risk factors for recurrence. Two predictors suggest that genetic/long-term environmental exposures also predispose to RUTI.

Adolescent↗
PubMed2000

Comparison of the inactivation of canine and bovine parvovirus by freeze-drying and dry-heat treatment in two high purity factor VIII concentrates.

The inactivation of bovine parvovirus (BPV) and canine parvovirus (CPV) by freeze-drying and terminal dry-heat treatment at 80 degrees C for 72 h has been investigated in two high purity factor VIII concentrates. In one product, CPV was slightly more resistant to freeze-drying compared to BPV, i.e. 0.7 vs. 1.4 log. However, BPV was substantially more resistant to heat-treatment compared to CPV, i.e. 1.3 vs. > 3.1 log inactivation after 72 h at 80 degrees C. In a second product, CPV was also slightly more resistant to freeze-drying than BPV, i.e. 0.2 vs. 1.3 log inactivation. However, heat-treatment gave essentially similar inactivation for both viruses, i.e. 2.8-3.4 log after 72 h at 80 degrees C. In conclusion, the resistance of these parvovirus models is dependent both on the type of virus and on the specific product involved.

Animals↗
PubMed2000

Does better functional result equate with better quality of life? Implications for surgical treatment in familial adenomatous polyposis.

PURPOSE: The main impetus for a patient with familial adenomatous polyposis to choose colectomy with ileorectal anastomosis over ileal pouch-anal anastomosis is the better functional result. However, does better functional result necessarily translate into better overall quality of life? Previous studies of other diseases have demonstrated no such correlation. This study was performed to determine whether any relationship exists between functional result and quality of life in patients with familial adenomatous polyposis after ileorectal anastomosis and ileal pouch-anal anastomosis. METHODS: All patients with familial adenomatous polyposis who underwent colectomy with ileorectal anastomosis or proctocolectomy with ileal pouch-anal anastomosis from 1980 to 1998 were studied. Functional data were obtained by questionnaire. Health-related quality of life was assessed by two validated instruments, the SF-36 Physical and Mental Health Summary Scales and the SF-36 Health Survey, which measure physical and mental functioning and eight separate health-quality dimensions, including health perception, physical and social functioning, physical and emotional role limitations, mental health, bodily pain, and energy or fatigue. RESULTS: Data were obtained in 44 of 68 patients, 14 with ileorectal anastomosis and 30 with ileal pouch-anal anastomosis. No differences were demonstrated between the two groups for patient age, mean follow-up time, and mean patient age at operation. Functional results were worse for the ileal pouch-anal anastomosis group vs. the ileorectal anastomosis group in number of bowel movements per day (7.5 vs. 5.2; P < 0.05), leakage (43 vs. 0 percent; P < 0.01), pad usage (17 vs. 0 percent; P < 0.01), perianal skin problems (33 vs. 7 percent; P < 0.01), food avoidance (80 vs. 43 percent; P < 0.01), and inability to distinguish gas (37 vs. 7 percent; P < 0.01). Results of the health-related quality-of-life surveys, however, demonstrated no difference between the ileal pouch-anal anastomosis and ileorectal anastomosis groups. The Physical and Mental summary scales for the ileal pouch-anal anastomosis and ileorectal anastomosis groups were not significantly different (Physical Health Scale, 50.3 vs. 50.9; Mental Health Scale, 51.7 vs. 49.6), and none of the eight dimensions of the SF-36 health survey demonstrated statistical differences between the ileal pouch-anal anastomosis and ileorectal anastomosis groups. CONCLUSION: Better functional results were not equated with better quality of life in this pilot study. Although patients with the ileorectal anastomosis have better functional results than those with ileal pouch-anal anastomosis, the measured health-related quality of life as determined by a validated generic health-related quality-of-life instrument is the same for both groups. These results suggest that all patients with familial adenomatous polyposis might be optimally treated with an ileal pouch-anal anastomosis. More importantly, this study suggests that health-related quality of life should play a greater role in the evaluation of care and treatment in colon rectal surgery.

Adenomatous Polyposis Coli↗
PubMed2000

Effects of contraceptive method on the vaginal microbial flora: a prospective evaluation.

A prospective evaluation of 331 university women who were initiating use of oral contraceptive pills (OCPs), a cervical cap, diaphragm-spermicide, or other spermicidal methods was done to assess the effects of commonly used contraceptive methods on the vaginal flora. Vaginal introital cultures were performed at baseline and then weekly for 1 month. The prevalence of Escherichia coli vaginal colonization and of abnormal vaginal Gram stain scores (Nugent criteria) increased significantly among women using a cervical cap or diaphragm-spermicide but not among women using OCPs. Women with E. coli colonization were significantly more likely to have an abnormal Nugent score and an absence of lactobacilli. In a multivariate model, use of spermicidal contraception in the preceding week was associated with an abnormal Nugent score and with colonization with E. coli, Enterococcus species, and anaerobic gram-negative rods. Thus, spermicidal methods of contraception are associated with alterations of the vaginal microflora that consequently may predispose women to genitourinary infections.

Adolescent↗
PubMed1998

Functional results after perineal complications of ileal pouch-anal anastomosis.

PURPOSE: This study investigated the functional significance of perineal complications after ileal pouch-anal anastomosis. METHODS: Review of a prospective registry of 628 patients was undertaken. Bowel function was assessed by detailed functional questionnaire. Statistical analyses were performed using chi-squared and Fisher's exact probability tests. RESULTS: Of 628 patients, 153 (24.4 percent) had 171 perineal complications. The 277 control patients had no complications. Complications included 66 (10.5 percent) anastomotic strictures, 28 (4.5 percent) anastomotic separations, 36 (5.7 percent) pouch fistulas, 41 (6.5 percent) episodes of pelvic sepsis, and 18 (2.9 percent) patients with multiple complications. After these complications were addressed, the pouch failure rate was low (10 percent); in 90 percent of patients, the pouch could be salvaged. Most pouch failures were the result of pouch fistulas, and most occurred in patients ultimately diagnosed with Crohn's disease. Functional results after cure of these perineal complications revealed no significant functional differences between control patients and those cured of anastomotic separations, anastomotic strictures, and pouch fistulas. Only a few minor differences were demonstrated in function after an episode of pelvic sepsis. The major deterioration in function occurred after treatment for multiple perineal complications. CONCLUSIONS: An appreciable number of perineal complications occur after ileal pouch-anal anastomosis. Pouch-perineal fistulas are associated with the highest pouch failure rate. The majority of these fistulas occur in patients ultimately diagnosed with Crohn's disease or indeterminate colitis. Although there is no substitute for good technique and sound clinical judgment in the success of ileal pouch-anal anastomosis, if perineal complications are successfully treated, functional outcome is equivalent to that in patients without perineal complications.

Anastomosis, Surgical↗
PubMed1998

Fatigue rate index as a new measurement of external sphincter function.

PURPOSE: Assessment of sustained voluntary contraction of the external sphincter is helpful in evaluating the patient who has a defecation disorder on presentation. A new index of external sphincter function is described. METHOD: A prospective registry of patients referred for computerized anal manometry using standard protocols was reviewed. Patients were grouped by primary symptoms; those with overlapping complaints were excluded. The rate of fatigue, defined as the change in stationary squeeze over a 40-second period of voluntary contraction, was calculated by linear regression analysis. Fatigue rate index, a calculated measure of time necessary for the external sphincter to become completely fatigued, was determined to permit comparison of external sphincter fatigue in patients with different complaints. RESULTS: Twenty-six healthy volunteers (15 women; mean age, 45 years), 33 patients with a primary complaint of anal seepage (13 women; mean age, 53 years), 75 patients with gross incontinence (61 women; mean age, 53 years), and 49 patients with severe constipation (41 women; mean age, 45 years) were evaluated. Mean resting and squeeze pressures were 55 mmHg and 107 mmHg for volunteers, 37 mmHg and 97 mmHg for patients with seepage, 30 mmHg and 49 mmHg for incontinent patients, and 56 mmHg and 93 mmHg for constipated patients. Pudendal neuropathy, as evidenced by a prolonged pudendal nerve terminal motor latency (> 2.4 ms), was identified in 13 percent of volunteers, 32 percent of patients with seepage, 54 percent of incontinent patients, and 38 percent of constipated patients. Mean fatigue rate index was 3.3 minutes for volunteers, 2.3 minutes for seepage patients, 1.5 minutes for incontinent patients, and 2.8 minutes for constipated patients. Compared with volunteers and patients with seepage, the incontinent patients had a significantly shorter fatigue rate index (P < 0.05; Student's t-test), which was independent of the variations in resting pressure (P < 0.05; two-way analysis of variance). CONCLUSION: The external anal sphincter is normally subject to fatigue. Patients with worsening degrees of incontinence have a predictably lower fatigue rate index. Fatigue rate index is a simple measure of external sphincter integrity, which may be used in assessment of sphincter function and future treatment protocols.

Anal Canal↗
PubMed1998

Inverse association of H2O2-producing lactobacilli and vaginal Escherichia coli colonization in women with recurrent urinary tract infections.

Women with recurrent urinary tract infection (UTI) often demonstrate persistent vaginal colonization with Escherichia coli. Since strains of lactobacilli that produce hydrogen peroxide inhibit the growth of E. coli, the absence of these strains may predispose to E. coli colonization and to UTI. To test this hypothesis, vaginal introital cultures were obtained from 140 women, 65 with recurrent UTI (case-patients) and 75 without (controls). Vaginal E. coli colonization was significantly more frequent in case-patients than controls (35% vs. 11%; P < .001) and in women without H2O2-positive lactobacilli than in women with (odds ratio [OR], 4.0; P = .01). Spermicide use was associated with greater risk of vaginal E. coli colonization (OR, 12.5; P < .001) and with absence of H2O2-positive lactobacilli (OR, 2.9; P = .04). The inverse association between H2O2-positive lactobacilli and vaginal E. coli colonization remained in case-patients after controlling for spermicide use (OR, 6.5; P = .02). Thus, absence of H2O2-positive lactobacilli may be important in the pathogenesis of recurrent UTI by facilitating E. coli introital colonization.

Adult↗
PubMed1997

Evolutionary changes in the pathologic diagnosis after the ileoanal pouch procedure.

PURPOSE: Inadequate initial differentiation between ulcerative colitis and Crohn's disease may lead to a diagnosis of indeterminate colitis. Construction of an ileoanal pouch in these patients may result in significant morbidity and pouch failure when the ultimate diagnosis is Crohn's disease. METHOD: We prospectively studied 543 patients with idiopathic inflammatory bowel disease to determine whether a patient's pathologic diagnosis changed with time and how it affected outcome. RESULTS: Preoperative diagnosis was ulcerative colitis in 499 patients, indeterminate colitis in 42 patients, and Crohn's disease in 2 patients. Prior colectomy was performed in 58 percent of patients with ulcerative colitis and in all patients with indeterminate colitis and Crohn's disease. Postoperatively, the diagnosis changed in 20 patients with ulcerative colitis (13 to indeterminate colitis, 7 to Crohn's disease). Another two patients with indeterminate colitis showed evidence of Crohn's disease in the resected rectal specimen. As patients were followed up, an additional 13 patients were found to have Crohn's disease (5 indeterminate colitis, 8 ulcerative colitis). With the current diagnosis, perineal complications and pouch failure occurred, respectively, in 23 and in 2 percent of patients with ulcerative colitis, in 44 and in 12 percent of patients with indeterminate colitis, and in 63 and in 37 percent of patients with Crohn's disease. Pathologic diagnosis was altered in 35 patients (6 percent) overall, with a 12-fold increase in the diagnosis of Crohn's disease. Only 3 percent of patients with ulcerative colitis compared with 13 percent of patients with indeterminate colitis had a change in diagnosis to Crohn's disease (P = 0.006; Fisher's exact test). CONCLUSION: Pouch-related complications, eventual pouch failure, and discovery of underlying Crohn's disease occurred in a significant number of patients with a diagnosis of indeterminate colitis. Until more accurate diagnostic differentiation is available, caution is advised in recommending the ileoanal pouch procedure to patients with indeterminate colitis.

Adolescent↗