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Biomedical subjects

R C Peck

Publications and source records attributed to R C Peck.

18 recordsLinked to original sources
PubMed1997

Estimating the exposure and fatal crash rates of suspended/revoked and unlicensed drivers in California.

There have been a number of studies conducted during the past three decades which show that most suspended/revoked (S/R) drivers violate their license action and continue to drive during their period of disqualification. Traffic safety researchers also suspect that S/R drivers are overinvolved in traffic crashes, but this is difficult to demonstrate because of the lack of good data on their prevalence among all road users. This paper applies the quasi-induced exposure method to fatal crash data obtained from the National Highway Traffic Safety Administration's Fatal Accident Reporting System, to generate exposure and crash rate estimates for S/R drivers in California. The results show exposure rates of 8.8% and 3.3% for suspended/revoked and unlicensed drivers, respectively, and that, compared to validly licensed drivers, the former are overinvolved in fatal crashes by a factor of 3.7:1, and the latter 4.9:1. These findings provide support for efforts to better control S/R and unlicensed drivers. The paper also discusses serious limitations to using quasi-induced exposure to estimate the numbers of such drivers on California roads, and concludes that it is not suited to this task.

Accidents, Traffic↗
PubMed1997

The impact of mail contact strategy on the effectiveness of driver license withdrawal.

The California Department of Motor Vehicles currently uses first-class mail to notify drivers of a suspension or revocation of their driving privilege. The served drivers are instructed to sign and return the order and any driver's license to the department, thereby establishing proof of the driver's knowledge of the order. The establishment of proof is considered essential in the prosecution of drivers cited for operating a motor vehicle while under a suspension or revocation (California Vehicle Code Section 14601). However, past research indicates that a majority of drivers fail to comply with the order. In an attempt to increase proof rates, the present study developed and evaluated a number of mailing strategies for various categories of suspensions and revocations. Among the mailing factors evaluated were (1) use of certified mail, (2) use of a follow-up contact, (3) use of a postage paid return envelope and (4) masking the Department of Motor Vehicles return address of the certified mail action notice. The results indicate that there are significant differences between the type of mail contact employed as well as between the different categories of suspension or revocation reason. The most effective strategies (certified mail, return receipt requested) resulted in proof rates of approximately 60-70% compared to approximately 25% for the current first-class mailing procedure. An analysis of subsequent driving records indicated that certified mail also increased the percentage of convictions which were prosecuted as 14601 violations, while decreasing the total number of entries (convictions and accidents) accumulated during suspension or revocation.

Automobile Driving↗
PubMed1994

Psychometric and biographical correlates of drunk-driving recidivism and treatment program compliance.

The primary objective of this study was to assess the extent to which drunk-driving (DUI) recidivism and DUI treatment program compliance could be predicted from psychometric, biographical, drinking history and prior-driving-record variables. These analyses were performed on data from 7,316 DUI offenders initially collected in Sacramento County, California, from September 1977 through January 1981. For most analyses, the recidivism measure was a composite of major convictions (DUI, reckless, hit-and-run), nighttime (6 PM-6 AM) and alcohol-related accidents during the 4-year interval following treatment assignment. The prediction of recidivism was highly significant for both the construct sample and the 25% cross-validation sample. The predictive accuracy was low, however, as evidenced by multiple Rs of < .30. The predicted rates of recidivism generated for each individual by the regression equation were cross tabulated by other criteria of interest, including total accidents and total injury and fatal accidents. Offenders at high risk of recidivating had substantially higher rates of accidents. The results indicate that reasonably accurate prediction of recidivism is only possible for discriminating between offenders at the extremes of the recidivism expectancy distribution. The above approach was also used to isolate factors predictive of program compliance (successfully completing treatment). In all cases, the prediction of compliance was highly statistically significant. In general, compliance was much more predictable than was subsequent DUI recidivism. Those offenders having a high probability of being noncompliant were much more likely to recidivate and have accidents than were those with favorable compliance expectancies.

Accidents, Traffic↗
PubMed1991

The long-term traffic safety impact of a pilot alcohol abuse treatment as an alternative to license suspensions.

During the 4-year period following a repeat driving under the influence (DUI) conviction, participants in 12-month treatment programs had worse overall traffic safety records than did recipients of license suspensions. The results from a series of analyses using repeated measures analysis of covariance showed that, in comparison with license-suspension recipients: (i) participants had significantly higher rates (70%) of nonalcohol-related accidents and convictions, (ii) participants had a significantly lower rate (9%) of alcohol-related convictions, but no difference was found on alcohol-related accidents, and (iii) participants had a significantly higher rate (30%) of total accidents (p less than .05). These results suggest that the use of license-suspension waiver as an incentive to participate in a drinking driver program had a negative impact on traffic safety. The predicted reductions in alcohol-related accidents among program participants did not occur, and reductions in nonalcohol-related accidents, which could have been achieved with license suspensions, were sacrificed. It was recommended that some other alternative besides license-suspension waivers be used as an inducement for repeat DUI offenders to participate in treatment.

Accidents, Traffic↗
PubMed1991

Recognition of cholinergic agonists by the muscarinic receptor. 2. Pilocarpine.

The conformational potential energy surface of the muscarinic agonist pilocarpine is studied by molecular mechanics (MMP2) and by semiempirical (AM1) and ab initio self-consistent-field (SCF) calculations. Six minima were located, two of which correspond to the known X-ray structures of pilocarpine. Possible active conformations of pilocarpine are inferred from the potential energy surfaces used in conjunction with the proposed active conformation of muscarine previously obtained from a theoretical model.

Models, Molecular↗
PubMed1984

Cardioprotective effects of enalapril in acute myocardial ischemia.

Enalapril, a new potent orally active angiotensin-converting enzyme inhibitor, was studied in cats subjected to acute myocardial ischemia. Enalapril, administered intravenously (2 mg/kg, plus 2 mg/kg/h) 30 min after ligation of the left coronary artery, significantly reduced the pressure-rate index, an indicator of myocardial oxygen demand. This was confirmed in isolated cat papillary muscles where enalapril reduced contractile force by 5-10%. During myocardial ischemia, enalapril reversed the elevated S-T segment of the electrocardiogram toward normal 2 h after the onset of ischemia. Moreover, enalapril significantly blunted the increases in circulating creatine kinase (CK) activity, as well as significantly prevented the loss in myocardial CK activity. These changes correlated with reduced myocardial loss of compounds containing free amino-nitrogen. Enalapril effectively acted as a converting enzyme inhibitor over the 5-hour course of the observation period. However, enalapril also acted as an angiotensin antagonist in isolated coronary arteries, a finding that may help explain its efficacy in myocardial ischemia. Enalapril did not appear to stabilize the membranes of cat liver lysosomes, and thus probably does not protect the ischemic myocardium by lysosomal stabilization.

Acute Disease↗
PubMed1982

Protective actions of dexamethasone in acute cerebral ischemia.

The effects of glucocorticoids on cerebral integrity during cerebral ischemia (CI) are not clear. We induced CI in rabbits by occlusion of the left external carotid artery and injection of sodium arachidonate (NaAr) in the left internal carotid artery. We investigated the effect of dexamethasone (DEXA) on NaAr--induced CI. We examined four groups: a) Sham CI, b) CI, c) CI + Dopamine (80 micrograms/kg/min), and d) CI + Dopamine + DEXA (6 mg/kg). The EEG was recorded over the hemisphere injected with NaAr. After 240 min of observation, the brain was sampled to measure water content and to examine the cerebral vasculature microscopically. The dose of NaAr was similar in all ischemic groups (ie, 0.45 to 0.50 mg). In both CI, and CI + Dopamine groups, the EEG became flat in all 13 rabbits. Moreover, the water content of the left hemisphere increased (P less than 0.01 vs Sham CI), but that of the right side only slightly. In the CI + Dopamine + DEXA group, only one rabbit out of seven showed a flat EEG. Water content of the left side increased slightly and that of the right side not at all. Microscopic examination of the brain showed obstruction of cerebral arterioles in the left hemisphere in rabbits given NaAr. Thus, DEXA protects the brain from edema induced by NaAr, when blood pressure is maintained by dopamine. This is associated with preservation of cerebral electrical activity. However, dopamine alone was unable to preserve the EEG or protect against edema formation during cerebral ischemia.

Acute Disease↗
PubMed1981

Protective effect of nifedipine in the hypoxic perfused cat liver.

The effects of the calcium antagonist nifedipine on isolated perfused cat livers were studied during 150 min of normoxic or hypoxic perfusion with Krebs-Henseleit solution. Hypoxic livers perfused with the nifedipine vehicle exhibited significantly higher increases in perfusion pressure, perfusate lactate dehydrogenase and cathepsin D activities, as well as amino-nitrogen concentrations compared to the control normoxic group. In contrast, the nifedipine + hypoxia group showed no significant difference in any of these variables from the control livers. Nifedipine (0.3 microgram/ml) protected the liver during hypoxia and that this protection may have stemmed from its inhibition of Ca++ influx which has been linked in irreversible cell death.

Animals↗
PubMed1981

Mechanism of protection against arachidonate induced sudden death by glucocorticoid.

Dexamethasone at a dose of 6 mg.kg-1 given to rabbits for three days prior to challenge with sodium arachidonate (2 mg.kg-1) intravenously, improved survival from 0% to 90% (p less than 0.01). Dexamethasone, given for shorter periods prior to arachidonate injection resulted in survival rates from 17% to 40%. In dexamethasone (3 days) treated rabbits, plasma thromboxane B2 concentrations were only increased by 30% compared with increases of 950% in untreated rabbits (p less than 0.001). Dexamethasone treated rabbits did not exhibit pulmonary thrombosis as did untreated rabbits given arachidonate. However, platelet rich plasma from both control and treated rabbits was aggregated by 0.2 mM arachidonate in vitro. The mechanism of the protective effect of dexamethasone appears to be related to induction of enzymes or stimulation of clearance of injected arachidonic acid, since steroid treated rabbits cleared labeled arachidonic acid more rapidly than untreated rabbits.

Animals↗
PubMed1981

Biphasic actions of chlorpromazine and mepacrine on modulation of hepatic cell injury in the perfused cat liver.

The effect of chlorpromazine (CPZ) and mepacrine on hypoxic liver cell damage was studied using an isolated perfused cat liver preparation. High concentrations of CPZ (10(-4) M) significantly augmented the hypoxic leakage of the lysosomal enzyme, cathepsin D, and the cytoplasmic enzyme, lactate dehydrogenase (LDH) into the perfusate. The per cent free cathepsin D activity of hepatic tissue was significantly higher in the 10(-4) M CPZ treated groups (87%) than in the vehicle group (65%). CPZ at a concentration of 10(-6) M also possessed a detrimental effect on hypoxic liver integrity but to a lesser extent compared to 10(-4) M. In contrast, low concentrations of CPZ (10(-7) M) showed a protective effect during hypoxia (i.e., significantly lower perfusate cathepsin D activity and per cent free cathepsin D activity) compared to livers receiving only the vehicle. Mepacrine, another phospholipase A2 inhibitor, showed no significant effect on hypoxic liver damage at concentration of 10(-6) and 5 x 10(-5) M. CPZ has a biphasic action on liver integrity during hypoxia, low concentrations being protective and high concentrations are deleterious. Mepacrine had no significant effect in the hypoxic liver.

Amines↗