Search PubMed⌕ Search

Biomedical subjects

Robert J Petrella

Publications and source records attributed to Robert J Petrella.

At least 19 recordsLinked to original sources
PubMed2007

Prevalence, treatment, and control of hypertension in primary care: gaps, trends, and opportunities.

Since most cases of hypertension are managed in family practice, estimates of the prevalence, treatment, and control in the primary care population are needed to adequately address the burden of hypertension in Canada as it has in other countries. The authors used a large primary care research database to determine the prevalence of hypertension between 2000 and 2003. Blood pressure recordings were used to estimate the rates of prevalence, treatment, and control of hypertension for the overall population and for important subgroups. The prevalence of hypertension was 17.3%, most patients had untreated hypertension (68.6%), and only 15.8% had blood pressure treated and controlled. Higher rates of treatment and control were observed among older adults, those with type II diabetes, and those with a previous myocardial infarction. Odds of achieving target blood pressure were significantly better when combination therapy vs monotherapy was used. The prevalence of hypertension in primary care is high and most patients remain untreated; however, increased risk appears to lead to better treatment and control.

Adolescent↗
PubMed2006

Improving management of musculoskeletal disorders in primary care: the Joint Adventures Program.

Musculoskeletal disorders represent a large and growing clinical challenge to primary care clinicians. Unfortunately, there appears to be a gap in current training and continuing education to meet this challenge. We used script concordance within a continuing medical education program entitled "Joint Adventures" to assist family physicians to acquire the knowledge, skills, and tools they need to improve their management of musculoskeletal disorders. Program workshops were coordinated through a national continuing education program of the College of Family Physicians of Canada. A group of 54 experts in musculoskeletal disorders including family physicians, rheumatologists, and orthopedists developed cases for six areas of management that were identified by family physicians during a needs survey delivered at a national scientific congress in primary care. Script concordance methodology was used in the Joint Adventures workshop to address knowledge gaps or lack of group consensus in the six areas including (1) diagnosis of osteoarthritis, (2) treatment and management of osteoarthritis, (3) treatment and management of rheumatoid arthritis, (4) diagnosis and treatment of back pain, (5) diagnosis and treatment of fibromyalgia and diagnosis, and (6) treatment of shoulder pain. Each workshop session included 5-30 family physicians, a specialist expert, and a family physician facilitator. Before each session, a group needs assessment was conducted to identify which one or two of the six cases would be used. Perceived knowledge and skill acquisition, self-assessed change in practice, and satisfaction with the program were measured at the conclusion of each session and again at 3 months post program. All programs were delivered from March 2003 to September 2005. Six hundred and fifty family physicians from across Canada completed the program. In general, participants reached concordance with each case. Measures of knowledge and skill acquisition and self-assessed change in practice were significantly improved with high rates of program satisfaction. The Joint Adventures program provided family physicians with knowledge and skills that changed their care of musculoskeletal disorders. This was achieved using consensus that was sensitive to local needs. Further use should be evaluated in other areas of medical practice as well.

Canada↗
PubMed2006

Cerebral and muscle tissue oxygenation in acute hypoxic ventilatory response test.

Eight men were exposed to progressive isocapnic hypoxia for 10 min to test the hypothesis that (i) cerebral and muscle tissue would follow similar deoxygenation profiles during an acute hypoxic ventilatory response (AHVR) test; and (ii) strong cerebrovascular responsiveness to hypoxia would be related to attenuated cerebral deoxygenation. End-tidal O(2) concentration was reduced from normoxia (approximately 102 mmHg) to approximately 45 mmHg while arterial oxygen saturation (SpO2 %) declined from 98+/-1% to 77+/-7% (P<0.001). Near-infrared spectroscopy (NIRS)-derived local cerebral tissue (frontal lobe) deoxyhemoglobin increased 5.55+/-2.22 microM, while oxyhemoglobin and tissue oxygenation index decreased 2.57+/-1.99 microM and 6.2+/-3.4%, respectively (all P<0.001). In muscle (m. vastus lateralis) the NIRS changes from the initial normoxic level were non-significant. Cerebral blood velocity (V(mean), transcranial Doppler) in the middle cerebral artery increased from 53.4+/-10.4 to 60.6+/-11.6 cms(-1) (P<0.001). In relation to the decline in SpO2 % the mean rate of increase of V(mean) and AHVR were 0.33+/-0.19 cms(-1)%(-1) and 0.52+/-0.20l min(-1)%(-1), respectively. We conclude that cerebral, but not muscle, tissue shows changes reflecting a greater deoxygenation during acute hypoxia. However, the changes in NIRS parameters were not related to cerebrovascular responsiveness or ventilatory chemosensitivity during graded hypoxia.

Acute Disease↗
PubMed2006

Do patients receive recommended treatment of osteoporosis following hip fracture in primary care?

BACKGROUND: Osteoporosis results in fractures and treatment of osteoporosis has been shown to reduce risk of fracture particularly in those who have had a history of fracture. METHODS: A prospective study was conducted using patients admitted to a hip fracture rehabilitation program at a large referral center to evaluate the use of treatments recommended for secondary prevention of osteoporotic fracture between September 1, 2001 and September 30, 2003. The frequency of medication use for the treatment of osteoporosis including estrogen replacement therapy, bisphosponates, calcitonin, calcium and vitamin D therapy was determined on admission, at 6 weeks post discharge and one year following discharge. All patients were discharged to the care of their family physician. All family physicians in the referral region received a copy of the Canadian Consensus recommendations for osteoporosis management 1-3 months prior to the study. RESULTS: During the study period, 174 patients were enrolled and 121 completed all assessments. Fifty-seven family physicians were identified as caring for 1 or more of the study patients. Only 7 patients had previous BMD, only 5 patients had previously been prescribed a bisphosponate and 14 patients were taking calcium and/or vitamin D. All patients were prescribed 2500 mg calcium, 400 IU vitamin D and 5 mg residronate daily during rehabilitation and at discharge.Following discharge, a significant improvement was seen in all clinical indices of functional mobility, including the functional independence measure (FIM), walking distance, fear of falling score (FFS), and the Berg balance score (BBS). At six weeks a significant (p < 0.01) decrease in calcium and vitamin D use was observed. All patients remained compliant with residronate therapy. At twelve months 71 patients remained on residronate (p < 0.01), 10 were now taking alternate bisphosphonate therapy and few were taking calcium and/or vitamin D (p < 0.001). FIM, FFS and Berg scores were significantly decreased from discharge (p < 0.001) while walking distance was unchanged. CONCLUSION: Few patients admitted for hip fracture had previously taken recommended osteoporosis therapy including bisphosphonates. While compliance with Canadian Consensus recommendations was observed at six weeks, this was not the case at twelve months post hip fracture rehabilitation. Interventions to improve not only the detection and treatment of osteoporosis but also the ongoing treatment and management post-fracture need to be developed and implemented.

Aftercare↗
PubMed2006

Efficacy and safety of coadministered amlodipine and atorvastatin in patients with hypertension and dyslipidemia: results of the AVALON trial.

The AVALON study was a randomized, multicenter trial to assess the efficacy and safety of coadministered amlodipine and atorvastatin in patients with hypertension and dyslipidemia. Phase one was an 8-week, double-blind, double-dummy, placebo-controlled period whereby patients received amlodipine 5 mg, atorvastatin 10 mg, amlodipine 5 mg and atorvastatin 10 mg, or placebo. Thereafter, all patients received single-blind amlodipine 5 mg and atorvastatin 10 mg for 8-weeks, followed by 12 weeks of open-label treatment where doses could be titrated to improve low-density lipoprotein cholesterol and blood pressure control. A total of 847 patients entered the double-blind phase. At Week 8, 45% of the patients receiving amlodipine 5 mg and atorvastatin 10 mg reached both their blood pressure and low-density lipoprotein cholesterol goals, compared with 8.3% with amlodipine (p < 0.001), 28.6% with atorvastatin (p < 0.001), and 3.5% with placebo. At 28 weeks, 67.1% of patients coadministered amlodipine and atorvastatin (mean doses, 7.6 mg and 28.4 mg, respectively) achieved both targets. Framingham estimated 10-year risk of coronary heart disease declined from baseline levels of 15.1% to 6.9% at Week 28. Following coadministered treatment, the adverse events reported were similar to either agent alone. Concomitant administration of amlodipine and atorvastatin is an effective and well tolerated treatment for coexisting hypertension and dyslipidemia.

Adolescent↗
PubMed2006

A prospective, randomized, double-blind, placebo controlled study to evaluate the efficacy of intraarticular hyaluronic acid for osteoarthritis of the knee.

OBJECTIVE: To assess the efficacy of intraarticular (IA) injections of hyaluronic acid (HA) compared to placebo in patients with osteoarthritis (OA) of the knee; and to assess patient satisfaction with treatment relative to placebo, and whether there is a difference between a series of 3 versus 6 consecutive IA injections. METHODS: We conducted a randomized, double-blind, placebo controlled, 2-arm parallel design trial of 106 patients with radiologically confirmed knee OA. Two-milliliter IA injections using 20 mg/ml HA sodium salt or saline placebo were administered once weekly over 3 weeks (HA and placebo groups), followed by once weekly IA injection with 2.0 ml (20 mg/ml) HA for a further 3 consecutive weeks. The primary efficacy assessment included Western Ontario and McMaster Universities osteoarthritis index (WOMAC) score for knee pain (Week 3 score). Secondary efficacy assessments included WOMAC scores for knee pain at Weeks 6 and 12 (followup), as well as WOMAC stiffness, physical function and quality of life scores, visual analog scale (VAS) scores for pain at rest and following walking and stepping activity, range of knee joint motion, and global patient satisfaction with treatment and quality of life using the SF-36. RESULTS: After 3 weeks of study treatment, both treatment groups showed improvements in knee function, the HA group showing a greater improvement compared to placebo in WOMAC knee pain score (p < 0.01). The HA group showed greater (p < 0.05) improvement in the overall WOMAC score and VAS pain following walking and stepping activity at Week 3. Results from all other secondary efficacy assessments at Weeks 6 and 12 including patient satisfaction were similar and were not statistically significant between treatment groups, and there were no significant differences between groups for adverse events. CONCLUSION: Intraarticular HA was superior to placebo in improving knee pain and function, with no difference between 3 or 6 consecutive injections for the primary efficacy assessment.

Aged↗
PubMed2005

Awareness and misconception of hypertension in Canada: results of a national survey.

BACKGROUND: The Canadian Heart Health Surveys were the last Canadian population-based physical measures surveys (conducted between 1988 and 1992) that determined that hypertension in Canada was poorly managed. Hypertension was undetected in almost one-half of all hypertensive Canadians surveyed, and only 13% of those with hypertension were treated and controlled to recommended blood pressure targets. The reasons for poor control are likely multifactorial; however, a lack of public awareness and understanding of hypertension may contribute to the epidemic of uncontrolled hypertension in Canada. METHODS: A national telephone survey was conducted comprising 1001 randomly selected men and women older than 40 years of age to determine the level of public awareness, understanding and misconception of hypertension in Canada. The survey was balanced for region, age and sex. RESULTS: Thirty-four per cent of respondents had been diagnosed with high blood pressure or hypertension by a health care professional, but only 58% of respondents had ever discussed their blood pressure with a physician, and only 44% were able to identify their own blood pressure or differentiate blood pressure levels considered to be above or below recommended targets. Overall, respondents had a poor understanding of the consequences of high blood pressure or hypertension. The majority were unaware of the association between hypertension and heart disease (80%), heart attack (66%), kidney disease (98%), damage to blood vessels (95%) and premature death (74%). Respondents also had limited knowledge of lifestyle issues affecting hypertension, despite 44% indicating that they were overweight and 18% identifying themselves as smokers. Almost two-thirds (63%) thought hypertension had clearly identifiable signs or symptoms, although they believed that hypertension was not a serious medical condition. Most respondents (59%) falsely believed that they would not develop hypertension and 38% thought that they would be able to control hypertension without the aid of a physician if they did have hypertension. CONCLUSIONS: While hypertension-related complications are preventable, lack of public awareness and misconceptions about hypertension and hypertensive complications are common and may, in part, be associated with ongoing inadequate Canadian awareness, treatment and control rates for hypertension. Increasing public awareness of hypertension using public education and health provider strategies should be a high national health priority.

Adult↗
PubMed2005

Electrostatic energies and forces computed without explicit interparticle interactions: a linear time complexity formulation.

A rapid method for the calculation of the electrostatic energy of a system without a cutoff is described in which the computational time grows linearly with the number of particles or charges. The inverse of the distance is approximated as a polynomial, which is then transformed into a function whose terms involve individual particles, instead of particle pairs, by a partitioning of the double sum. In this way, the electrostatic energy that is determined by the interparticle interactions is obtained without explicit calculation of these interactions. For systems of positive charges positioned on a face-centered cubic lattice, the calculation of the energy by the new method is shown to be faster than the calculation of the exact energy, in many cases by an order of magnitude, and to be accurate to within 1-2%. The application of this method to increase the accuracy of conventional truncation-based calculations in condensed-phase systems is also demonstrated by combining the approximated long-range electrostatic interactions with the exact short-range interactions in a "hybrid" calculation. For a 20-A sphere of water molecules, the forces are shown to be six times as accurate using this hybrid method as those calculated with conventional truncation of the electrostatic energy function at 12 A. This is accomplished with a slight increase in speed, and with a sevenfold increase in speed relative to the exact all-pair calculation. Structures minimized with the hybrid function are shown to be closer to structures minimized with an exact all-pair electrostatic energy function than are those minimized with a conventional 13-A cutoff-based electrostatic energy function. Comparison of the energies and forces calculated with the exact method illustrate that the absolute errors obtained with standard truncation can be very large. The extension of the current method to other pairwise functions as well as to multibody functions, is described.

Algorithms↗
PubMed2005

Impact of a social marketing media campaign on public awareness of hypertension.

BACKGROUND: Barriers to high blood pressure (BP) awareness and control are exacerbated by poor knowledge of the consequences and uncertainty regarding how to and who should direct care. We developed a social marketing hypertension awareness program to determine baseline awareness, knowledge, and treatment behavior, and then studied the impact of a targeted, media intervention among randomly surveyed adults at risk in a representative urban community compared to a control community immediately and 6 months after the intervention. METHODS: The program consisted of three random-digit telephone surveys conducted in two mid-sized Ontario cities to determine high BP awareness, knowledge, and treatment behavior. Using baseline knowledge and attitudes toward high BP in both communities, a social marketing awareness strategy and mass media intervention campaign incorporating television, radio, print, direct to patient, and interactive techniques was developed and implemented in the test city only. Both test and control cities were resurveyed immediately after and at 6 months post-media intervention to detect change and decay. RESULTS: A sample of 6873 men and women more than 35 years old who were aware of their high BP demonstrated a high prevalence of high BP in the general population ( approximately 34% in both communities). At baseline this population had poor knowledge of their own BP numbers and poor understanding of the diseases related to high BP. Although few considered high BP a health concern, they had good understanding of lifestyle interventions for high BP prevention and control. The number of the respondents who claimed to have high BP increased immediately after intervention in the test city (38%; P < .02), whereas the number of respondents who were treated and uncontrolled decreased (P < .05) compared to control. There was a significant increase in patients' knowledge of consequences and in their perception that they were most responsible for high BP control in the test city (P < .005) compared to control. At 6 months, no further changes were observed in those claiming to have high BP in either city, whereas decay to baseline in those treated but not controlled and those claiming responsibility for their BP control was observed in the test city. No changes were observed in the control city accept for an increase from baseline to 6 months in the percentage claiming to be treated but uncontrolled. We were unable to determine whether the increase in number treated but uncontrolled was due to a higher treatment rate, similar treatment rate but more patients being uncontrolled, or a combination of these scenarios. CONCLUSIONS: High BP is very prevalent in adults and knowledge of lifestyle options for management is encouraging. In the short-term, although our media awareness program increased the number of respondents claiming to have high BP and patient self-efficacy for BP control, this was not maintained. We did not change knowledge of consequences or importantly, the health importance of BP control among those at risk. Hence, in addition to a mass media campaign, attention should be focused on dissemination of awareness knowledge information through medical professionals at the point of care.

Adult↗
PubMed2005

Hyaluronic acid for the treatment of knee osteoarthritis: long-term outcomes from a naturalistic primary care experience.

OBJECTIVE: Intraarticular hyaluronic acid is indicated for patients with osteoarthritis of the knee. However, clinical experience, especially efficacy and adverse events, with repeated injection series in the long term are limited. DESIGN: Patients were referred to a large primary care center for management of osteoarthritis of the knee. All were naive to intraarticular hyaluronic acid therapy and met our entry criteria, including resting visual analog scale pain of > 45 mm, radiographic confirmation of unilateral knee grade 1-3 osteoarthritis, and willingness to receive intraarticular therapy. Patients received a three-intraarticular injection series with Suplasyn (10 mg/ml, 2-ml injection) over 3 wks. Patients were instructed to return for consideration of repeat injection series based on their perception of pain restricting daily activity and a resumption of severity similar to their initial presentation. This prospective naturalistic cohort was followed for 6.7 yrs. Patients completed baseline assessment of rest and walking visual analog scale pain (primary efficacy variable), completed a 5-point categorical global satisfaction score, and recorded adverse events and concomitant therapeutic modality use at each study visit. Patients returned for consideration of a repeat injection series based on their perception of symptom severity and were eligible if their resting visual analog scale pain was > 45 mm. The three-injection series and data collection were repeated, and again, patients were given similar instructions regarding consideration of a third injection series. RESULTS: Of 897 referral patients, 537 (mean age, 68 +/- 8 yrs; mean duration of symptoms, 7.4 +/- 4.1 yrs) met our criteria, and only 21 patients did not return for a second injection series. The mean time between first and second series was 27 +/- 7 wks. The change in walking visual analog scale pain was significantly improved from baseline after the first series (81.3%, P < 0.001) and second series (86.7%, P < 0.0001). Similarly, resting visual analog scale pain was significantly decreased from baseline after the first (P < 0.001) and second (P < 0.001) series, and patient satisfaction was significantly improved with each injection series (P < 0.03 and P < 0.01). Very few adverse events were recorded and were limited to local pain and swelling. Use of concomitant therapeutic modalities at presentation for a second injection series included: nonsteroidal anti-inflammatory drugs/cyclooxygenase-2 medications (37%), acetaminophen (31%), oral nutraceuticals (12%), and physical therapy and bracing (12%). CONCLUSIONS: Intraarticular hyaluronic acid injections were highly effective in improving resting and walking pain in patients with osteoarthritis of the knee on a first and a second treatment series. Duration of symptom control was about 6 mos, and the therapy was highly satisfactory to patients and was associated with very few local adverse events and limited use of concomitant therapeutic modalities. These data support the potential role of intraarticular hyaluronic acid as an effective long-term therapeutic option for patients with osteoarthritis of the knee.

Adjuvants, Immunologic↗
PubMed2004

Longitudinal changes in aerobic power in older men and women.

The purpose of this study was to describe the longitudinal (10 yr) decline in aerobic power [maximal O(2) uptake (Vo(2 max))] and anaerobic threshold [ventilatory threshold (T(Ve))] of older adults living independently in the community. Ten years after initial testing, 62 subjects (34 men, mean age 73.5 +/- 6.4 yr; 28 women, 72.1 +/- 5.3 yr) achieved Vo(2 max) criteria during treadmill walking tests to the limit of tolerance, with T(Ve) determined in a subset of 45. Vo(2 max) in men showed a rate of decline of -0.43 ml.kg(-1).min(-1).yr(-1), and the decline in Vo(2 max) was consequent to a lowered maximal heart rate with no change in the maximum O(2) pulse. The women showed a slower rate of decline of Vo(2 max) of -0.19.ml.kg(-1).min(-1).yr(-1) (P < 0.05), again with a lowered HR(max) and unchanged O(2) pulse. In this sample, lean body mass was not changed over the 10-yr period. Changes in Vo(2 max) were not significantly related to physical activity scores. T(Ve) showed a nonsignificant decline in both men and women. Groupings of young-old (65-72 yr at follow-up) vs. old-old (73-90 yr at follow-up) were examined. In men, there were no differences in the rate of Vo(2 max) decline. The young-old women showed a significant decline in Vo(2 max), whereas old-old women, initially at a Vo(2 max) of 19.4 +/- 3.1 ml.kg(-1).min(-1), showed no loss in Vo(2 max). The longitudinal data, vs. cross-sectional analysis, showed a greater decline for men but similar estimates of the rates of change in women. Thus the 10-yr longitudinal study of the cohort of community-dwelling older adults who remained healthy, ambulatory, and independent showed a 14% decline in Vo(2 max) in men, and a smaller decline of 7% in women, with the oldest women showing little change over the 10-yr period.

Aged↗
PubMed2004

The role of carbon-donor hydrogen bonds in stabilizing tryptophan conformations.

Although most side-chain torsion angles correspond to low-energy rotameric positions, deviations occur with significant frequency. One striking example arises in Trp residues, which have an important role in stabilizing protein structures because of their size and mixed hydrophobic/hydrophilic character. Ten percent of Trp side-chains have unexplained conformations with chi(2) near 0 degrees instead of the expected 90 degrees. The current work is a structural and energetic analysis of these conformations. It is shown that many Trp residues with these orientations are stabilized by three-center carbon-donor hydrogen bonds of the form C-H...X...H-C, where X is a polar hydrogen-bond acceptor in the environment of the side-chain. The bridging hydrogen bonds occur both within the Trp side-chain and between the side-chain and the local protein backbone. Free energy maps of an isolated Trp residue in an explicit water environment show a minimum corresponding to the off-rotamer peak observed in the crystallographic data. Bridging carbon-donor hydrogen bonds are also shown to stabilize on-rotamer Trp conformations, and similar bridging hydrogen bonds also stabilize some off-rotamer Asp conformations. The present results suggest a previously unrecognized role for three-center carbon-donor hydrogen bonds in protein structures and support the view that the off-rotamer Trp side-chain orientations are real rather than artifacts of crystallographic refinements. Certain of the off-rotamer Trp conformations appear to have a functional role.

Aspartic Acid↗
PubMed2004

Effect of rehabilitation on hip and knee proprioception in older adults after hip fracture: a pilot study.

OBJECTIVE: Impaired proprioception may predispose patients with hip fracture to increased risk of future disability. The purpose of the study was to determine the effect of rehabilitation on proprioceptive changes in both the hip and knee joints of patients after hip fracture. DESIGN: Data were collected on 30 patients with hip fracture (mean age, 79.6 +/- 6.7 yrs) who attended physical and occupational therapy sessions five times per week during a rehabilitation hospital stay of 24.8 +/- 8.1 days. Proprioception was assessed with an electrogoniometer within 48 hrs of admission to and discharge from the rehabilitation unit. The passive-to-active reproduction of joint angle technique determined absolute angular error in non-weight-bearing positions at 15, 30, and 60 degrees of hip flexion and knee extension in both injured and noninjured sides. RESULTS: Absolute angular error decreased significantly (P < 0.05) from admission (5.3 +/- 2.6 degrees, 4.1+/- 3.1 degrees) to discharge (3.0 +/- 2.3 degrees, 2.8 +/- 3.1 degrees) in hip flexion and knee extension, respectively, on the injured side. Absolute angular error was significantly less (P < 0.05) at 15 degrees compared with 30 and 60 degrees of hip flexion at admission and discharge on the injured side. CONCLUSIONS: Hip and knee joint proprioception significantly improved in the injured side after the rehabilitation program. This may be an important outcome regarding future disability in this population.

Aged↗
PubMed2004

Lifestyle management for type 2 diabetes. Are family physicians ready and willing?

OBJECTIVE: To determine practices and perceptions of family physicians regarding lifestyle interventions to prevent and manage type 2 diabetes (T2D). DESIGN: Confidential mailed survey. SETTING: Canadian family practices. PARTICIPANTS: Random, stratified sample of 1499 respondents to the 2001 National Family Physician Workforce Survey. MAIN OUTCOME MEASURES: Physicians' self-reported practice patterns and perceptions of lifestyle counseling for patients at risk for, and diagnosed with, T2D. RESULTS: Response rate was 53% (749/1410). Respondents frequently asked patients at risk for, or diagnosed with, T2D about physical activity and weight loss, but far fewer provided written advice, particularly about physical activity. Respondents thought counseling with such interventions as generic patient handouts was preferable to more intensive lifestyle management strategies, such as appointments to provide stage-matched counseling on physical activity. Most respondents thought family physicians should perform lifestyle interventions but realized they are confounded by such barriers as patients' lack of interest and limited referral resources. CONCLUSION: Family physicians keen to implement lifestyle interventions for T2D are hampered by barriers and use of ineffective strategies.

Adult↗
PubMed2003

An improved method for nonbonded list generation: rapid determination of near-neighbor pairs.

Generation of the list of near-neighbor pairs of atoms not bonded to each other is a key feature of many programs for calculating the energy and energy derivatives for large molecules. Because this step can take a significant amount of CPU time, more efficient nonbonded list generation can speed up the energy calculations. In this article, a novel nonbonded list generation algorithm, BYCC, is introduced. It combines certain features of other algorithms and achieves more rapid nonbonded list generation; a factor of approximately 2.5 for a molecule of 5000 atoms with a cutoff in the 10 A range is obtained on Hewlett-Packard (HP) and Alpha processors, without greatly increasing memory requirements.

Algorithms↗
PubMed2003

Muscle fiber number in the biceps brachii muscle of young and old men.

We have compared the number of muscle fibers in the biceps brachii muscle (BB) of six old men (82.3 +/- 4.3 years) and six young men (21.2 +/- 1.9 years). Muscle fiber number was estimated by dividing the maximal area of the BB, determined with magnetic resonance imaging, by the mean fiber area of the BB determined in a muscle biopsy. The percentage of type II fibers in the BB ( approximately 60%) and the type I fiber area were not different between the groups. The BB area (-26%), type II fiber area (-24%), mean fiber area (-20%), and maximal voluntary contraction strength (MVC) of the elbow flexor muscles (-27%) were lower in the old than young group. However, the estimated number of muscle fibers was not significantly different between the young (253000) and old (234000) men. Consequently, the smaller BB area of the old men could be explained primarily by a smaller type II fiber size. These findings suggest that old age is not associated with a reduced number of muscle fibers in the BB. The relative contribution of a reduction in fiber number to age-related muscle atrophy may be muscle-dependent.

Adult↗