Biomedical subjects

Robert Parkes

Publications and source records attributed to Robert Parkes.

7 recordsLinked to original sources

PubMed2006

High prevalence of masked hypertension in treated hypertensive patients with type 2 diabetes mellitus.

This study was undertaken to determine whether self-measured home blood pressure (BP) readings were comparable to clinic visit BP readings in hypertensive type II diabetic patients. We measured the BP of 27 hypertensive patients at home and during the clinic visits over a three week period. The BP readings were analyzed using a mixed linear model with mean daytime ambulatory measure as a covariate. We found that, although there was no significant difference in the mean systolic BP between home and clinic readings (0.6 mm Hg), the mean home BP readings were significantly higher (difference = 6.8 mm p < 0.0006). The proportion of masked hypertension, defined as elevated home systolic or diastolic BP (or both) values despite normal clinic visit BP values, was 40.7%. Three diastolic and one systolic BP measurement at home achieved a reliability coefficient of 0.8. Self-measurement of BP gave highly reliable readings when they were compared with blind readings taken by a trained professional using a mercury sphygmomanometer. We conclude that self-measured BP at home identifies a high prevalence of masked hypertension in treated hypertensive type 2 diabetic patients and that it represents a valuable management adjunct to ensure maximum benefit from antihypertensive drug therapy.

Aged↗

PubMed2005

TP53 mutations and outcome in osteosarcoma: a prospective, multicenter study.

PURPOSE: Mutations of the TP53 gene have been associated with resistance to chemotherapy as well as poor prognosis in many different malignancies. This is the first prospective study of the prognostic value of somatic TP53 mutations in patients with newly diagnosed extremity osteosarcoma. PATIENTS AND METHODS: One hundred ninety-six patients with high-grade, nonmetastatic osteosarcoma of the extremities were enrolled from seven tertiary care institutions and observed prospectively for tumor recurrence (median follow-up duration, 44 months). All patients received neoadjuvant or adjuvant chemotherapy and surgery. Tumors were analyzed for the presence of TP53 mutations by polymerase chain reaction single-strand conformation polymorphism analysis and direct DNA sequencing. The association of the status of the TP53 gene with the risk of systemic recurrence was examined using survival analyses with traditional and histologic markers as prognostic factors. RESULTS: Patient age was the only factor that varied with TP53 gene status (P = .05). No relationship was identified between TP53 status and systemic relapse (relative risk, 1.24; P = .41). Analyses based on missense or nonsense mutations gave similar results (P > .10). In multivariate analysis, large (> 9 cm) tumor size (relative risk, 1.9; P = .006) and poor histologic response (< or = 90% necrosis) to chemotherapy (relative risk, 2.14; P = .02) were the only significant independent predictors of systemic outcome. CONCLUSION: We found no evidence that TP53 mutations predict for development of metastases in patients with high-grade osteosarcoma. Identification of other genes that influence chemotherapy response and clinical outcome in osteosarcoma is needed to facilitate further improvements in patient outcomes.

Adolescent↗

PubMed2003

Developmental changes in left and right ventricular diastolic filling patterns in mice.

Developmental changes in left and right ventricular diastolic filling patterns were determined noninvasively in isoflurane-anesthetized outbred ICR mice. Blood velocities in the mitral and tricuspid orifices were recorded in 16 embryos at days 14.5 (E14.5) and 17.5 of gestation (E17.5) using an ultrasound biomicroscope and also serially in three groups of postnatal mice aged 1-7 days (n = 23), 1-4 wk (n = 18), and 4-12 wk (n = 27) using 20-MHz pulsed Doppler. Postnatal body weight increased rapidly to 8 wk. Heart rate increased rapidly from approximately 180 beats/min at E14.5 to approximately 380 beats/min at 1 wk after birth and then more gradually to plateau at approximately 450 beats/min after 4 wk. Ventricular filling was quantified using the ratio of peak velocity of early ventricular filling due to active relaxation (E wave) to that of the late ventricular filling caused by atrial contraction (A wave) (peak E/A ratio) and the ratio of the peak E velocity to total time-velocity integral of E and A waves (peak E/total TVI ratio). Both ventricles had similar diastolic filling patterns in embryos (peak E/A ratio of 0.28 +/- 0.02 for mitral flow and 0.27 +/- 0.02 for tricuspid flow at E14.5). After birth, mitral peak E/A increased to >1 between the third and fifth day, continued to increase to 2.25 +/- 0.25 at approximately 3 wk, and then remained stable. The tricuspid peak E/A ratio increased much less but stabilized at the same age (increased to 0.79 +/- 0.03 at 3 wk). The peak E/total TVI ratio showed similar left-right differences and changes with development. Age-related changes were largely due to increases in peak E velocity. The results suggest that diastolic function matures approximately 3 wk postnatally, presumably in association with maturation of ventricular recoil and relaxation mechanisms.

Anesthesia↗

PubMed2003

Balloon angioplasty or medical therapy for hypertensive patients with atherosclerotic renal artery stenosis? A meta-analysis of randomized controlled trials.

PURPOSE: The optimal treatment for hypertensive patients with atherosclerotic renal artery stenosis is controversial. We performed a meta-analysis comparing the effects of balloon angioplasty and medical therapy in these patients. METHODS: We searched MEDLINE, EMBASE, the Science Citation Index, the Cochrane Controlled Trials Registry, and reference lists. Authors of published trials were contacted. RESULTS: We identified three trials involving a total of 210 patients with moderate-to-severe (> or = 50%) unilateral or bilateral atherosclerotic renal artery stenosis and poorly controlled hypertension who were followed for at least 3 months after intervention. Balloon angioplasty was significantly more effective in reducing blood pressure than was medical therapy; the weighted mean difference between the two treatments was -7 mm Hg (95% confidence interval [CI]: -12 to -1 mm Hg) for systolic blood pressure and -3 mm Hg (95% CI: -6 to -1 mm Hg) for diastolic blood pressure. There was no consistent difference in changes in renal function. Patients treated with balloon angioplasty were more likely to have patent renal arteries after 12 months (52% vs. 19%; odds ratio [OR] = 4.2; 95% CI: 1.8 to 9.8), used fewer antihypertensive medications, and appeared to have fewer major cardiovascular and renovascular complications (OR = 0.27; 95% CI: 0.06 to 1.23; P = 0.09). CONCLUSION: Balloon angioplasty has a modest but significant effect on blood pressure and should be considered for patients with atherosclerotic renal artery stenosis and poorly controlled hypertension. There is no evidence supporting its use in improving or preserving renal function, although none of the trials were designed to address this issue.

Adult↗

PubMed2002

Reconstructive surgery for failed ileal pouch-anal anastomosis: a viable surgical option with acceptable results.

PURPOSE: Salvage procedures for failed ileal pouch-anal anastomoses frequently require total reconstruction with a combined abdominal and perineal approach. The aim of this study was to determine the indications for surgery and the outcomes in this group of patients. METHODS: All patients who underwent combined abdominal and perineal ileal pouch-anal anastomosis reconstruction at the Mount Sinai Hospital between 1982 and 2000 were reviewed. Data were collected prospectively in the inflammatory bowel disease database. RESULTS: Sixty-three reconstructive procedures were performed in 57 patients, with a mean age of 33.9 (+/-10.4) years at the time of reconstruction. There were 14 males. The mean follow-up was 69.1 months. The initial indication for ileal pouch-anal anastomosis was ulcerative colitis in 98 percent. The primary indication for reconstruction was pouch-vaginal fistula in 21 patients, long outlet in 14, pelvic sepsis in 14, ileoanal anastomotic stricture in 5, pouch-perineal fistula in 2, and chronic pouchitis in 1. The mean operative time was four hours (+/-1.1), the average blood loss was 500 mL (+/-400), and the average length of stay was 10.3 days (+/-4.6). All patients had a diverting ileostomy. Forty-two (73.6 percent) of the patients have a functioning pouch. Seven (12.3 percent) patients have had their pouch excised. The ileostomy has not yet been closed in 8 (14 percent) patients; 3 of these patients are awaiting closure, whereas the remaining 5 have a permanently defunctioning ileostomy. Eighty-nine percent have ten or fewer bowel movements per day. No patients are incontinent of stool during the day, whereas two patients are incontinent at night. Seventeen percent complain of frequent urgency. Despite this, more than 80 percent rate their physical and psychological health as good to excellent. CONCLUSION: Reconstructive pouch surgery has a high success rate in experienced hands. The functional results in those whose pouch is in use are good.

Adult↗

PubMed2002

Risk of small bowel obstruction after the ileal pouch-anal anastomosis.

OBJECTIVE: To determine the incidence of small bowel obstruction (SBO), to identify risk factors for its development, and to determine the most common sites of adhesions causing SBO in patients undergoing ileal pouch-anal anastomosis (IPAA). METHODS: All patients undergoing IPAA at Mount Sinai Hospital were included. Data were obtained from the institution's database, patient charts, and a mailed questionnaire. SBO was based on clinical, radiologic, and surgical findings. Early SBO was defined as a hospital stay greater than 10 or 14 days because of delayed bowel function, or need for reoperation or readmission for SBO within 30 days. All patients readmitted after 30 days with a discharge diagnosis of SBO were considered to have late SBO. RESULTS: Between 1981 and 1999, 1,178 patients underwent IPAA (664 men, 514 women; mean age 40.7 years). A total of 351 episodes of SBO were documented in 272 (23%) patients during a mean follow-up of 8.7 years (mean 1.29 episodes/patient). Fifty-four patients had more than one SBO. One hundred fifty-four (44%) of the SBOs occurred in the first 30 days; 197 (56%) were late SBOs. The cumulative risk of SBO was 8.7% at 30 days, 18.1% at 1 year, 26.7% at 5 years, and 31.4% at 10 years. The need for surgery for SBO was 0.8% at 30 days, 2.7% at 1 year, 6.7% at 5 years, and 7.5% at 10 years. In patients requiring laparotomy, the obstruction was most commonly due to pelvic adhesions (32%), followed by adhesions at the ileostomy closure site (21%). A multivariate analysis showed that when only late SBOs were considered, performance of a diverting ileostomy and pouch reconstruction both led to a significantly higher risk of SBO. CONCLUSIONS: The risk of SBO after IPAA is high, although most do not require surgical intervention. Thus, strategies that reduce the risk of adhesions are warranted in this group of patients to improve patient outcome and decrease healthcare costs.

Adult↗

PubMed2002

Risk factors for low bone density in Crohn's disease.

Osteopenia and osteoporosis are prevalent in patients with Crohn's disease (CD). We conducted a cross-sectional study on consecutive patients with CD to assess the prevalence and factors associated with low bone mass density (BMD). One hundred sixty-eight patients with CD were evaluated. Baseline demographics, medical and surgical history, calcium intake, physical activity, steroid use, Harvey Bradshaw Index, blood and urine tests, and dual-energy X-ray absorptiometry were obtained. Sixty-seven (40%) and seventy-five (45%) patients had osteopenia of the femur and spine, respectively. Ten to 11% of patients had osteoporosis. Of the 40 patients who never used steroids, 19 (48%) had osteopenia of the femur and 12 (30%) of the spine. Significant associations were found between BMD and age, body mass index, and serum magnesium. Lifetime steroid use was a weaker predictor of bone loss. Duration of disease did not correlate with BMD when adjusted for age. At follow-up at a mean of 2 years, BMD declined in the femur but not the spine. However, those with ongoing steroid use had lower spine BMD. A significant number of patients with CD have osteopenia. Age was the most important predictor of bone loss. Significant proportion of steroid naive patients had osteopenia, which implies that mechanisms other than steroid use are also involved in bone loss in CD. Disease activity, systemic inflammation, and hormonal and genetic factors may all be important determinants of bone loss in CD.

Absorptiometry, Photon↗