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Biomedical subjects

Peter Black

Publications and source records attributed to Peter Black.

13 recordsLinked to original sources
PubMed2006

Trends in major cardiovascular risk factors in Auckland, New Zealand: 1982 to 2002-2003.

AIM: To describe recent trends in cardiovascular risk factors between 1982 and 2002-2003 in Auckland, New Zealand. METHODS: Data on non-Maori and non-Pacific adults aged 35-74 years were derived from four population-based surveys carried out in 1982, 1986-88, 1993-94, and 2002-3 using similar protocols. RESULTS: Systolic blood pressure levels continue to decline since the 1982 survey, together with a reduction in the proportion of people with raised blood pressure who were untreated. The downwards trend in cigarette smoking observed between 1982 and 1993-94 appears to have halted. Serum total cholesterol declined from 6.18 mmol/L in 1982 to 5.62 mmol/L in 2002-3 in men; and from 6.26 mmol/L in 1982 to 5.37 mmol/L in 2002-3 in women. HDL-cholesterol levels continued to rise over this time period. Use of lipid lowering medications increased from 0% in the 1982 and 1986-88 studies to 1.3% in men and 2.6% in women in the 1993-4 survey, and to 6.3% in men and 2.7% in women in the 2002-3 survey. The age-standardised mean body mass index increased from 25.6 (25.4-25.8) kg/m2 in 1982 to 27.2 (26.9-27.6) kg/m2 in 2002-3 in men; and from 24.5 (24.2-24.9) kg/m2 in 1982 to 26.6 (26.2-27.0) kg/m2 in women in 2002-3. The prevalence of overweight and obese people increased from 52.8% (49.7-55.9) to 70.9% (67.7-74.1) in men and from 36.5% (32.5-40.5) to 57.0% (53.4-60.6) in women. CONCLUSIONS: Trends in systolic blood pressure, raised blood pressure, serum cholesterol, HDL-cholesterol levels, and use of antihypertensive and cholesterol-lowering drug use in non-Maori and non-Pacific adult Aucklanders between 1982 to 2002-04 have been favourable. However, these favourable trends were, in part, counterbalanced by less favourable trends in body mass index, obesity, and cigarette-smoking. These findings suggest that the decline in cardiovascular mortality rates in New Zealand over the past 35 years may not be sustained.

Adult↗
PubMed2006

Blood pressure prevalences and levels for a multicultural population in Auckland, New Zealand: results from the Diabetes, Heart and Health Survey 2002/2003.

AIMS: To estimate ethnic-specific raised blood pressure (RBP) prevalences, blood pressure levels, and associations of systolic blood pressure (SBP) in the Auckland region. METHODS: A cross-sectional survey of adults aged between 35-74 years in the Auckland region. There were 1006 Maori, 996 Pacific people (mostly of Samoan, Tongan, Niuean, or Cook Islands origin), and 2021 Others (mainly Europeans). RESULTS: Approximately 1 in 3 Maori and Pacific people had RBP (defined arbitrarily as greater than and equal to 140/90 mmHg or on blood pressure-lowering treatment), compared to 1 in 5 Others. The prevalences of RBP (adjusted for age and gender) were: Maori 37%, Pacific people 38%, and Others 22%. Maori and Pacific people had higher average systolic and diastolic blood pressure levels than Others (adjusted for age and gender). This difference became non-significant when adjusted for body mass index (BMI). SBP was (on average) higher for: male gender, increased age, increased BMI, no tertiary education, high pulse rate, high cholesterol, high triglycerides, those on current blood pressure-lowering medication. SBP was (on average) lower for current cigarette smokers. CONCLUSION: Average blood pressure levels and the prevalences of RBP were higher in Pacific people and Maori compared to Others. BMI was identified as the major modifiable factor.

Adult↗
PubMed2006

Viable malignant germ cell tumor in the postchemotherapy retroperitoneal lymph node dissection specimen: can it be predicted using clinical parameters?

BACKGROUND: The presence of viable tumor in the surgical specimen after postchemotherapy retroperitoneal lymph node dissection (PC-RPLND) is associated with an increased risk of disease progression. The objective of this study was to determine whether the presence of viable tumor in the surgical specimen could be predicted. METHODS: Between 1980 and 2003, 236 patients underwent PC-RPLND for clinical Stage IIA or III nonseminomatous germ cell tumors (NSGCT). The authors retrospectively reviewed the medical records of those patients for pertinent clinical and treatment-related outcomes. A multivariate logistic regression analysis was used to evaluate whether clinical parameters were capable of predicting the presence of viable tumor in the surgical specimen. RESULTS: International Germ Cell Consensus Classification (IGCCC) risk categories could be assigned to 218 patients, with 101 patients in the good-risk category, 32 patients in the intermediate-risk category, and 85 patients in the poor-risk category. The incidence of viable tumor in the good-risk, intermediate-risk, and poor-risk categories was similar (17.8%, 15.6%, and 15.3%, respectively); however, the risk categories predicted disease-specific and recurrence-free survival (P = .022 and P < .0001, respectively). On multivariate analysis, an elevated serum alpha-fetoprotein (AFP) level prior to PC-RPLND (P = .05) and the size of the retroperitoneal mass on pathology review (P = .02) were predictive of viable tumor in the surgical specimen. CONCLUSIONS: Although IGCCC risk categories were correlated with disease-related outcomes, the risk groups had similar incidences of viable tumor. Elevated serum AFP levels prior to surgery and the size of the retroperitoneal mass in the resected specimen may help to predict viable tumor in the PC-RPLND specimen.

Adult↗
PubMed2005

Stereotactic radiotherapy for vestibular schwannomas: favorable outcome with minimal toxicity.

OBJECTIVE: To determine the outcome and toxicity in patients with vestibular schwannomas treated with conventionally fractionated stereotactic radiotherapy (SRT) and to identify prognostic factors that are predictive of outcome. METHODS: Between 1992 and 2001, 70 patients with vestibular schwannomas were treated with linear accelerator-based SRT in our institutions. Eleven patients had neurofibromatosis Type II (NF2). The median age was 53 years (range, 17-82 yrs). The median tumor volume was 2.4 cm3 (range, 0.05-21.1 cm3). The indications for SRT were distributed as follows: 47% newly diagnosed, 31% progressive tumors after watchful waiting, 3% adjuvant postoperative radiation, and 19% recurrent tumors after surgical resection. The median dose was 54 Gy in 1.8 Gy per fraction, prescribed to 95% of the isodose line. Relocatable stereotactic frames were used for daily treatments. The median follow-up was 45.3 months. RESULTS: Tumor recurrence was defined as progressive enlargement of tumor on follow-up magnetic resonance imaging studies. One patient had a tumor recurrence at 38 months after SRT. The actuarial tumor control rates were 100 and 98% at 3 and 5 years, respectively. Three patients with a median tumor volume of 16.2 cm3 required surgical resection for persistent or increasing symptoms at a median of 37 months. The actuarial freedom from resection rates were 98 and 92% at 3 and 5 years, respectively. In multivariate analysis, tumor volume at time of treatment was predictive for neurosurgical intervention (surgical resection or shunt placement) after SRT (P = 0.001). The 3- and 5-year actuarial rates of freedom from any neurosurgical intervention were 100 and 97% for patients with tumor volume less than 8 cm3 and 74 and 47% respectively for patients with tumor of at least 8 cm3 (P < 0.0001). The 3-year actuarial rates of facial and trigeminal nerve preservation were 99 and 96%, respectively. Surgery before SRT was predictive of posttreatment trigeminal neuropathy. The 3-year actuarial rates of freedom from trigeminal neuropathy were 86 and 98% for patients with and without previous resection, respectively (P = 0.04). There was no difference in tumor control and cranial nerve function preservation rates seen in NF2 patients compared with non-NF2 patients. No second primary cancer or malignant transformation was observed. CONCLUSION: SRT in the conventionally fractionated approach results in a very favorable outcome with minimal toxicity, with results comparable to those of the best of the radiosurgery series. Patients with large tumors are more likely to undergo neurosurgical interventions after SRT. Patients who have undergone previous surgery are at increased risk of developing trigeminal neuropathy.

Adolescent↗
PubMed2004

Perfusion MRI of U87 brain tumors in a mouse model.

Continuous arterial spin labeling (CASL) was used to obtain an index of cerebral blood flow (ICBF) in the normal mouse brain and in an orthotopic mouse model of human U87 high-grade glioma at 8.5 T. Under the assumption of a constant tissue:blood partition coefficient for water in different tissues, the mean ICBF (n = 14) was found to be 50 +/- 9 mL/100g/min for tumor core and 209 +/- 11 mL/100g/min for normal tissue. The apparent T(1) (T(1app)) was 2.01 +/- 0.06 sec for tumor core and 1.66 +/- 0.03 sec for normal tissue. The ICBF and the T(1app) values were significantly different (P < 0.001) between these two regions. The detailed changes of ICBF and T(1app) in the transition from the tumor core through the tumor periphery to surrounding tissue were studied. Immunohistochemistry indicated that tumor vascularity was not uniform, with microvessel density highest in normal brain and the tissue surrounding the tumor and lowest in the tumor core. The large difference in ICBF between the tumor core and normal tissue suggests that this index might be useful for the assessment of the efficacy of antiangiogenic therapy.

Animals↗
PubMed2004

Quantification of water diffusion and relaxation times of human U87 tumors in a mouse model.

Assessing the potential of anti-cancer agents can be greatly facilitated by applying MRI methods to investigations with animal models. Quantitative diffusion imaging, T1, and T2 measurements may offer valuable information for understanding properties of the tumor and for evaluating new therapeutic approaches. The human U87 high-grade glial tumor is widely used for cancer investigations in orthotopic murine models. The physiological features of this model at the cellular and sub-cellular level have not, however, been well characterized by MRI. In this study, we measured the diffusion, T1 and T2 characteristics of water in the human U87 tumor at 8.5 T in an orthotopic murine model in vivo and analyzed their detailed changes in the transition from the tumor core through the tumor periphery, and out to surrounding tissue using custom developed radial profile analysis software. For the tumor bearing mice (n = 10), the mean average apparent diffusion coefficient (ADC) of the tumor core was 1.03 +/- 0.02 ( x 10(-3) mm2/s), while in the contralateral normal brain it was 0.73 +/- 0.03 ( x 10(-3) mm2/s). The mean T1 in tumor was 2.03 +/- 0.08 s and in normal brain tissue was 1.64 +/- 0.06 s. The mean T(2) in tumor was 0.062 +/- 0.002 s and in normal brain tissue was 0.048 +/- 0.001 s. The mean ADC, T1 and T2 of the tumor compared to normal tissue were significantly different (p < 0.005).

Animals↗
PubMed2004

Comparison of rofecoxib and a multidose oxycodone/ acetaminophen regimen for the treatment of acute pain following oral surgery: a randomized controlled trial.

OBJECTIVE: To compare the efficacy of a single dose of rofecoxib 50 mg with a single dose of oxycodone/acetaminophen 10/650 mg over 6 h as well as with a multidose regimen of oxycodone/acetaminophen 10/650 mg followed by oxycodone/acetaminophen 5/325 mg over 24 h. RESEARCH DESIGN AND METHODS: In this double-blind, randomized, two-phase study, patients with moderate to severe pain after surgical extraction of >or= 2 third molars, including one mandibular impaction, were treated with rofecoxib 50 mg, oxycodone/acetaminophen 10/650 mg (singledose phase) followed by 5/325 mg every 6h as needed (multidose phase), or placebo. Patients rated their pain relief and intensity at 18 time points over 24 h. Efficacy was measured over 6 and 24 h by total pain relief (TOPAR), sum of pain intensity difference (SPID), and patient global assessment of response to therapy (PGART). Primary endpoint for the single dose comparison was TOPAR over 6 h; SPID was the key 24-h endpoint. Onset of analgesic effect, peak analgesic single dose of oxycodone/acetaminophen. effect, and duration of analgesic effect were also evaluated. Adverse experiences were recorded. RESULTS: 271 patients were randomized to treatment with rofecoxib (n = 121), oxycodone/acetaminophen (n = 120), or placebo (n = 30). For the single dose comparison, rofecoxib-treated patients achieved pain relief at least as effective as oxycodone/acetaminophentreated patients as assessed by TOPAR6 (12.9 vs 11.3, 95% CI on difference = [-0.1, 3.2], p = 0.059). Patients also rated a single dose of rofecoxib as at least as effective as multidose oxycodone/acetaminophen over 24 h on SPID24 (21.9 vs 18.1, 95% CI on difference = [-1.0, 8.8], p = 0.122). Patients treated with oxycodone/ acetaminophen had a shorter time to onset of analgesia than patients treated with rofecoxib (24 vs 35 min, p < 0.05). Patients in the active treatment groups achieved similar peak effects during the single-dose phase. Individuals treated with rofecoxib demonstrated a longer duration of analgesic effect than those treated with a Patients on active treatment demonstrated better efficacy than patients on placebo on these prespecified endpoints (p < 0.001 for both comparisons). Fewer rofecoxib than oxycodone/acetaminophen patients experienced adverse events (47.9 vs 75.8%, p < 0.001), including nausea (19.0 vs 42.5%, p < 0.001), vomiting (9.9 vs 24.2%, p < 0.01), and dizziness (7.4 vs 31.7%, p < 0.001). CONCLUSION: Patients treated with a single dose of rofecoxib 50 mg achieved an overall analgesic effect at least as effective as patients treated with a single-dose of oxycodone/acetaminophen 10/650 mg over 6 h and multidose oxycodone/acetaminophen over 24 h, with fewer adverse experiences of nausea (p < 0.001), vomiting (p < 0.01), and dizziness (p < 0.001).

Acetaminophen↗
PubMed2002

Ibuprofen arginate provides effective relief from postoperative dental pain with a more rapid onset of action than ibuprofen.

Ibuprofen is a safe and effective analgesic, but some formulations have a slow onset of action. Ibuprofen arginate is a rapidly absorbed salt designed to promote more rapid onset of analgesia. A clinical trial was conducted in 226 patients with postoperative dental pain to assess the analgesic efficacy and speed of onset of the arginine salt of ibuprofen compared with one of the commercially available forms of ibuprofen. Patients were administered a single dose of either ibuprofen arginate (200 mg or 400 mg), ibuprofen (200 mg or 400 mg), or placebo in this double-blind, randomized trial. To determine the onset of action of the study medication patients were required to note time to "any" pain relief and then time to "meaningful" pain relief, using the two-stopwatch method. Pain intensity and relief were assessed using traditional categorical scales over a 6-h period. Meaningful pain relief was achieved in 42 min and 24 min for ibuprofen arginate 200 mg and 400 mg, respectively, compared with 50 min and 48 min for ibuprofen 200 mg and 400 mg, respectively ( P<0.05). The results for the measurements of analgesic effectiveness [sum of pain intensity difference, total pain relief (TOTPAR), peak pain relief and overall evaluation of treatment] all showed that both doses of ibuprofen arginate and both doses of ibuprofen were significantly better than placebo and both 200-mg and 400-mg ibuprofen arginate doses were significantly better than ibuprofen 200 mg for peak pain relief. Mean plasma ibuprofen concentrations at 30 min and 60 min, respectively, were: ibuprofen arginine 200 mg, 13.9 micro g/ml and 15.7 micro g/ml; ibuprofen arginine 400 mg, 29.5 micro g/ml and 29.3 micro g/ml; ibuprofen 200 mg 2.5 micro g/ml and 5 micro g/ml; ibuprofen 400 mg, 2.3 micro g/ml and 7.4 micro g/ml. ( P<0.05). Adverse event profiles were similar across treatment groups. These results overall suggest that ibuprofen arginate when taken at doses equivalent to commercially available ibuprofen formulations produces analgesia that is faster in onset.

Adult↗
PubMed2002

Refluxing ureterointestinal anastomosis for continent cutaneous urinary diversion.

PURPOSE: We question the statement that anti-refluxing ureteral implantation is mandatory in low pressure, high capacity reservoirs. In a series of patients with ureteral obstruction after implantation with an anti-refluxing submucosal tunnel reimplantation was performed as a direct ureter-pouch anastomosis. The same technique was used for primary anastomosis in a later group of patients as the method of choice for ileocolic and colonic continent urinary diversion. MATERIALS AND METHODS: Direct ureteral reimplantation was performed in 10 patients in whom a total of 19 obstructed renal units were associated with an ileocolic reservoir. The retroperitoneal supracostal approach was used to avoid complications caused by repeat laparotomy. The ileocecal reservoir was opened superior and the obstructed ureter was identified and reimplanted via a buttonhole. The same technique was used for primary anastomosis in 20 patients (40 renal units), in whom the ureter was implanted in an ileocecal (10) or colonic (10) pouch. RESULTS: Postoperatively complications did not develop in any patient. Radiography of the pouch postoperatively showed renal reflux in only 1 renal unit. In the group with reimplanted ureters median followup was 81 months (range 10 to 120). Of the 19 obstructed ureters 14 returned to normal, while 5 showed persistent grade I dilatation. Median followup in patients with primary direct ureteral anastomosis was 20 months (range 2 to 36). Of the 22 preoperatively dilated systems 20 returned to normal and none of the 18 nondilated systems was obstructed. CONCLUSIONS: Direct ureter-pouch reimplantation proved to be simple and safe. When performed primarily for continent urinary diversion, the anastomosis was anti-refluxing in pouches with high capacity and low pressure. The advantage of this technique is the low risk of ureteral obstruction and subsequent deterioration in kidney function.

Anastomosis, Surgical↗
PubMed2002

A randomized, double-blind, placebo-controlled comparison of the analgesic efficacy, onset of action, and tolerability of ibuprofen arginate and ibuprofen in postoperative dental pain.

BACKGROUND: Because of its enhanced pharmacokinetic characteristics, ibuprofen arginate might be expected to provide faster pain relief than standard ibuprofen formulations in patients experiencing acute pain. OBJECTIVE: This study assessed the analgesic efficacy, speed of onset, and tolerability of ibuprofen arginate compared with a commercially available form of ibuprofen in patients with postoperative dental pain. METHODS: Patients were randomized to receive ibuprofen arginate 200 or 400 mg, ibuprofen 200 or 400 mg, or placebo in this multicenter, double-blind, double-dummy, parallel-group trial. Patients were observed for 6 hours after administration of a single dose of study medication. A repeated-dose, open-label phase followed. Pain intensity and pain relief were measured using traditional verbal descriptor scales; onset of analgesia was assessed using 2 stopwatches to measure the time to achievement of specific pain relief criteria. RESULTS: A total of 498 patients (219 men, 279 women; mean age, 21.5 years) participated in this study. Baseline pain was moderate in 388 patients (78%) and severe in 110 patients (22%). Meaningful pain relief was reached after a median of 29 and 28 minutes with ibuprofen arginate 200 and 400 mg, respectively, and after 52 and 44 minutes with ibuprofen 200 and 400 mg, respectively (all, P < 0.05). The percentages of patients who achieved meaningful pain relief within the first hour after treatment were 77.6% and 83.7% for ibuprofen arginate 200 and 400 mg, respectively, 61.0% and 63.0% for ibuprofen 200 and 400 mg, respectively, and 39.8% for placebo. The differences between ibuprofen arginate and ibuprofen were statistically significant (both doses, P < 0.05). Significantly greater numbers of patients achieved meaningful pain relief with ibuprofen arginate 400 mg compared with placebo from 20 minutes through 6 hours and with ibuprofen arginate 200 mg from 30 minutes through 6 hours (P < 0.05). Compared with placebo, a greater number of patients achieved meaningful pain relief with ibuprofen 400 mg from 45 minutes through 6 hours; with ibuprofen 200 mg. the corresponding interval was from I through 6 hours. After the first hour, pain reduction was similar for the similar doses of the 2 ibuprofen preparations. Median remedication times with both doses of ibuprofen arginate were similar to those with both doses of ibuprofen, ranging from 4.0 to 5.2 hours. Adverse-event profiles were similar between the 2 active medications. CONCLUSIONS: Ibuprofen arginate was effective in this population of patients experiencing moderate to severe pain after surgical extraction of > or = 1 impacted third molar, with 16 to 24 minutes' faster time to meaningful pain relief than with ibuprofen. The 2 formulations had similar tolerability profiles.

Adult↗
PubMed2002

Minimalist approach: functional mapping.

The ability to accurately map functional cortex both preoperatively and intraoperatively is an important neurosurgical challenge for the next decade. The central concept of preoperative mapping is to superimpose blood flow and electrical activation data on a three-dimensional matrix created by MR imaging and image processing. The gold standard, at present, is direct cortical stimulation, which can identify primary motor, sensory, speech, and visual cortices. Cortical mapping can be performed intraoperatively or through implanted subdural electrodes at the bedside. The tasks for the next decade include the validation of these preoperative techniques (fMRI, MEG, TMS, EP): 1. Correlation of direct cortical stimulation with advanced perioperative stimulation/monitoring systems, in a wide variety of cases. In addition, extension of these applications into intraoperative imaging systems like the GE Signa unit should also be envisaged. 2. Evaluation of how various pathologies such as AVMs, well-circumscribed tumors, and infiltrative tumors affect the data obtained by these techniques. 3. Expansion of mapping to areas outside the primary motor and sensory cortices, including those referred to as "associative" and to higher functions collectively termed as "cognition."

Brain↗