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Biomedical subjects

J B Ryan

Publications and source records attributed to J B Ryan.

At least 19 recordsLinked to original sources
PubMed2000

Descriptive spatial analysis of the epidemic of bovine spongiform encephalopathy in Great Britain to June 1997.

This was a spatial analysis of the epidemic of bovine spongiform encephalopathy (BSE) in Great Britain, based on agricultural census data collected between 1986 and 1996 and BSE case data collected up to June 1997. Kernel smoothing techniques were used to plot the distribution of BSE-positive cattle holdings per 100 holdings per square kilometre and the distribution of confirmed BSE cases per 100 head of cattle per square kilometre. In the early stages of the epidemic reported BSE cases were scattered widely throughout Great Britain, with no clearly identifiable focus. By June 1997, a statistically significant cluster of BSE-positive holdings was identifiable in the eastern part of the South west region of England. During the epidemic the highest densities of confirmed BSE cases per 100 cattle per square kilometre occurred in the greater part of the South west region of England and within Dyfed in the south west of Wales. In Wales, a small number of holdings experienced large numbers of confirmed BSE cases. In the South west region of England a large number of holdings experienced small numbers of confirmed cases. By June 1997, the distribution of BSE-positive holdings across Great Britain was largely determined by factors that influenced the amount of recycled infectious material they were exposed to.

Animals↗
PubMed2000

Temporal aspects of the epidemic of bovine spongiform encephalopathy in Great Britain: individual animal-associated risk factors for the disease.

The objectives of this study were first to determine the cumulative incidence of bovine spongiform encephalopathy (BSE) in the British cattle population from July 1986 to June 1997, secondly, to identify individual animal-associated risk factors that influenced the age of onset of clinical signs in confirmed BSE cases, and, thirdly, to assess the effectiveness of the measures introduced to control BSE during the epidemic. The analyses were based on the population of British cattle at risk, derived from agricultural census data collected between 1986 and 1996, and BSE case data collected up to June 30, 1997. The unit of interest was individual adult cattle recorded on annual agricultural censuses between June 1986 and June 1996. Univariate and multivariate survival analysis techniques were used to characterise the age of onset of clinical signs. In total 167,366 cases of BSE were diagnosed in Great Britain up to June 30, 1997. The cumulative incidence of BSE between July 1986 and June 1997 was 1.10 (95 per cent confidence interval [CI] 1.09 to 1.10) cases per 100 adult cattle at risk. Cattle from the South east, South west and Eastern regions of England had 4.26 to 5.96 (95 per cent CI 4.15 to 6.14) times as great a monthly hazard of being confirmed with BSE as cattle from Scotland. Compared with cattle born before June 1985, those born between July 1987 and June 1988 had 22.5 (95 per cent CI 22.1 to 22.8) times the monthly hazard of being confirmed with BSE, whereas those born in the 12 months after July 1988 had only 7.39 (95 per cent CI 7.24 to 7.54) times the monthly hazard of being confirmed with BSE. This reduction in hazard was directly attributable to the ban on the use of ruminant protein as a feed instituted in July 1988. Successive cohorts from 1989 to 1991 experienced further reductions in the hazard of experiencing BSE. The additional decrease in hazard observed for the 1990 cohort may be attributed to the effect of the Specified Bovine Offal ban instituted in September 1990.

Animals↗
PubMed2000

Temporal aspects of the epidemic of bovine spongiform encephalopathy in Great Britain: holding-associated risk factors for the disease.

The objectives of this study were first to describe the pattern of the epidemic of bovine spongiform encephalopathy (BSE) in Great Britain in terms of the temporal change in the proportion of all cattle holdings that had experienced at least one confirmed case of BSE to June 30, 1997, and secondly to identify risk factors that influenced the date of onset of a holding's first confirmed BSE case. The analyses were based on the population of British cattle at risk, derived from agricultural census data collected between 1986 and 1996, and the BSE case data collected up to June 30, 1997. The unit of interest was the cattle holding and included all those recorded at least once on annual agricultural censuses conducted between June 30, 1986, and June 30, 1996. The outcome of interest was the date on which clinical signs were recorded in a holding's first confirmed case of BSE, termed the BSE onset date. Univariate and multivariate survival analysis techniques were used to describe the temporal pattern of the epidemic. The BSE epidemic in Great Britain started in November 1986, with the majority of affected holdings having their BSE onset date after February 1992. After adjusting for the effect of the size and type of holding, holdings in the south of England (specifically those in the Eastern, South east and South west regions) had 2.22 to 2.43 (95 per cent confidence interval [CI] 2.07 to 2.58) times as great a monthly hazard of having a BSE index case as holdings in Scotland. After adjusting for the effect of region and type of holding, holdings with more than 53 adult cattle had 5.91 (95 per cent CI 5.62 to 6.21) times as great a monthly hazard of having a BSE index case as holdings with seven to 21 adult cattle. Dairy holdings had 3.06 (95 per cent CI 2.96 to 3.16) times as great a monthly hazard of having a BSE index case as beef suckler holdings. These analyses show that there were different rates of onset in different regions and in holdings of different sizes and types, that the epidemic was propagated most strongly in the south of the country, and that the growth of the epidemic followed essentially the same pattern in each region of the country, with modest temporal lags between them. The control measures imposed in 1988 and 1990 brought the expansion of the epidemic under control, although the rate of progress was slowed by those regions where the effectiveness of the control methods took some time to take full effect.

Animals↗
PubMed1998

Factors contributing to delayed extremity amputation in burn patients.

BACKGROUND: Previous series of traumatic amputations have noted that delay in amputation results in prolonged hospital stay and delayed rehabilitation. A series of major extremity amputations after burn injury was analyzed to identify the frequency of delayed amputation and to identify factors resulting in the delay. METHODS: Chart review of burn admissions between January of 1991 and December of 1995. RESULTS: Twenty-eight patients underwent a total of 44 major extremity amputations. Thirty-five amputations in 22 patients were performed by postburn day 16 (mean 4.3). Nine amputations in six patients were delayed beyond postburn day 26 (mean, 48.3). Delayed amputations occurred in the subgroups of deep thermal burns with extensive necrosis and thermal burns complicated by infections. Early amputation was associated with a 13.6% mortality rate, delayed amputation with a 50% mortality rate. CONCLUSION: There is a bimodal distribution of time to amputation determined by mechanism of injury, severity of burn, and infectious complications. Earlier identification of nonsalvageable limbs may decrease infectious complications and improve the chances of patient survival.

Adult↗
PubMed1998

Braced for impact: reducing military paratroopers' ankle sprains using outside-the-boot braces.

BACKGROUND: Ankle injuries account for 30 to 60% of all parachuting injuries. This study was designed to determine if outside-the-boot ankle braces could reduce ankle sprains during Army paratrooper training. METHODS: The randomized trial involved 777 volunteers from the U.S. Army Airborne School, Fort Benning, Ga. Of this group, 745 completed all study requirements (369 brace-wearers and 376 non-brace-wearers). Each volunteer made five parachute jumps, for a total of 3,674 jumps. RESULTS: The incidence of inversion ankle sprains was 1.9% in non-brace-wearers and 0.3% in brace-wearers (risk ratio, 6.9; p = 0.04). Other injuries appeared unaffected by the brace. Overall, 5.3% of the non-brace group and 4.6% of the brace group experienced at least one injury. The risk ratio for injured individuals was 1.2:1 (non-brace to brace groups; p = 0.65). CONCLUSION: Inversion ankle sprains during parachute training can be significantly reduced by using an outside-the-boot ankle brace, with no increase in risk for other injuries.

Adult↗
PubMed1998

Combating silent PPOs.

A silent PPO is a contracting entity that negotiates discounts with providers but sells access to the discounts to other, nonrelated parties after services are provided to individuals covered by the nonrelated parties' insurance policies. Healthcare financial managers should be alert to the presence of silent PPOs when entering into contract negotiations. To combat silent PPOs, a two-pronged approach--prevention and detection--is advisable. Factors to consider include appropriate contract language stating that all clients with access to the discounts have a contract with the PPO, presence of the PPO's logo on a patient's insurance card, and the PPO's willingness to limit the number of providers in its network. Warning signs that indicate the presence of a silent PPO include a high volume of retroactive reclassifications, single employers taking discounts from multiple PPO networks, or payments for services provided to single individuals coming from multiple PPO networks.

Contract Services↗
PubMed1997

A cohort study to examine maternally-associated risk factors for bovine spongiform encephalopathy.

This long-term cohort study, initiated in July 1989, was designed to examine maternally-associated risk factors for bovine spongiform encephalopathy (BSE), forming part of the epidemiological research programme to assess the risks of non-feedborne transmission of BSE. In this study, the incidence of BSE in offspring of cows which developed clinical signs of BSE is compared with that in offspring, born in the same calving season and herd, of cows which had reached at least six years of age and had not developed BSE. All offspring were allowed to live to seven years of age. The results indicate a statistically significant risk difference between the two cohorts of 9.7 per cent and a relative risk of 3.2 for offspring of cows which developed clinical BSE. However, there is some evidence that this enhanced risk for offspring of BSE cases declined the later the offspring was born, but was increased the later the offspring was born in relation to the stage of the incubation period of the dam. The results presented cannot distinguish between a genetic component and true maternal transmission or a combination of both risks, but they do not indicate either that the BSE epidemic will be unduly prolonged or that the future incidence of BSE in Great Britain will increase significantly.

Animals↗
PubMed1997

Risk of BSE from the import of cattle from the United Kingdom into countries of the European Union.

This study assesses quantitatively the risk that other countries, in particular those within the European Union, have incurred by importing cattle from the United Kingdom during the period before or shortly after the ban on the import of live breeding stock was introduced in 1989. It does this by assessing the probability that animals imported from the UK in a certain year would have become a detected BSE case, had they not been exported. Using the annual incidence rates available for separate birth cohorts and a given culling rate, a cumulative incidence for each birth cohort was calculated. These figures were then combined with the numbers of live breeding cattle imported from the UK into the other countries of the EU, to give an import-related risk index for each country, assuming that their culling rates were similar to that in Great Britain. The countries could thus be categorised in terms of the number of cases of BSE they might have expected.

Animals↗
PubMed1997

Viscoelastic characteristics of muscle: passive stretching versus muscular contractions.

This study compared the effects of repeated contractions and repeated passive stretches on the viscoelastic properties of muscle. The tibialis anterior (TA) muscles of eight anesthetized male New Zealand white rabbits were studied. In each rabbit, one hindlimb was randomly assigned to the repeated muscular contraction group (CON) and the contralateral hindlimb to the repeated passive stretch group (STRETCH). The passive tension at neutral length was measured in all muscles before and after both repeated muscular contractions or repeated passive stretches. In the CON hindlimb, the peroneal nerve was stimulated with a nerve stimulator for 1 s, and the resulting contractile force was measured. Stimulations were repeated every 10 s for a total of 10 contractions. In the STRETCH hindlimb, the TA was stretched from its shortest in vivo length to its maximum in vivo length 10 times at 20 cm x min-1. The maximum force generated during the first contraction in the CON group averaged 21.74 +/- 1.41 N, with a subsequent reduction with each muscle contraction to 13.66 +/- 0.81 N by the tenth contraction. The average peak tensile force in the STRETCH group was 17.39 +/- 2.61 N for the first passive stretch, decreasing to 13.57 +/- 1.84 by the tenth stretch. After repeated muscular contractions in the CON hindlimbs, the passive tension at neutral length decreased from 0.88 +/- 0.22 N to 0.42 +/- 0.08 N. After repeated passive stretches in the STRETCH hindlimbs, the passive tension at neutral length decreased from 1.16 +/- 0.17 N to 0.67 +/- 0.09 N. The percentage decreases in passive tension between the CON and STRETCH groups were not statistically significant (P = 0.24). The results show that stretching and contracting both result in tissue relaxation of the muscle-tendon unit. This finding may be a result of changes in the viscous elements of the connective tissue secondary to the forces generated by either stretches or contractions. This study suggests that well controlled isometric muscular contractions may result in decreased passive tension in a muscle at neutral length, a finding that one normally associates with passive stretching.

Animals↗
PubMed1997

Four techniques for managing the risk of capitation contracts.

Organizations that provide managed care must manage four major cost drivers if they are to achieve financial success under capitation. These cost drivers-number of lives covered, service frequency, service intensity, and cost per unit of service-represent risk factors that can be minimized using several insurance risk management strategies: bearing risk, sharing risk, transferring risk, and undertaking risk-reduction activities. No one strategy will be sufficient to ensure success under capitation; contracting organizations, therefore, should use a portfolio of strategies to manage risk.

Capitation Fee↗
PubMed1997

Degree of integration can influence organizational economic decisions.

When healthcare providers join to form contracting organizations to negotiate managed care contracts, the resulting organizations can be characterized by their degree of integration: tightly integrated (ie, a single bottom line) or loosely integrated (ie, economic independence of each affiliated entity is preserved). Tightly integrated organizations generally are more attractive to payers and better able to optimize returns on their managed care contracts.

Capitation Fee↗
PubMed1997

Men and women in optometry. II. Attitudes toward career and family.

BACKGROUND: Optometry has experienced a dramatic upward shift in the percentage of women entering the profession during the past 20 years. Our survey assessed the mechanisms for sustaining balance in professional and personal roles used by women optometrists and how these mechanisms may differ from those of their male colleagues. METHODS: A survey questionnaire was mailed to a large nationwide random sample of optometrists, composed of equal numbers of men and women. RESULTS: Data were analyzed from 353 men and 358 women; margin of error was +4%. Most of the respondents indicated they derived personal satisfaction from their career. A majority of both groups did not indicate that lack of time for their career was a source of frustration. However, significantly more women than men indicated some frustration in pursuing those activities that lead to career advancement. There were significant differences in response patterns of men and women about the effect of family, child care, and household work on their careers. CONCLUSIONS: Both men and women optometrists are satisfied with their careers and neither group feels compelled to choose between career and family. Optometrists do not fit into one pattern, but instead make individualized career choices on the basis of needs.

Attitude of Health Personnel↗
PubMed1996

Transmission dynamics and epidemiology of BSE in British cattle.

A comprehensive analysis of the bovine spongiform encephalopathy (BSE) epidemic in cattle in Great Britain assesses past, present and future patterns in the incidence of infection and disease, and allows a critical appraisal of different culling policies for eradication of the disease.

Age Factors↗
PubMed1996

Effects of postmortem freezing on tensile failure properties of rabbit extensor digitorum longus muscle tendon complex.

The tensile failures of extensor digitorum longus muscle tendon units from 16 male New Zealand White rabbits were studied in the fresh state (less than 30 minutes after death) and in the frozen/thawed state (frozen at -80 degrees C for 28 days and then warmed to 38 degrees C). Frozen/thawed extensor digitorum longus muscle tendon units had significantly lower values for load to failure (p < 0.01), energy absorbed to failure (p < 0.01), and strain at failure (p < 0.01), and they tended to fail at a different anatomic location (p < 0.01) (broadly at the fascia-muscle interface as compared with horizontally at the musculotendinous junction) than fresh units. The results of this study suggest that freezing muscle tendon units significantly alters their tensile failure characteristics.

Animals↗
PubMed1996

Partner risk: the hidden threat of capitated provider networks.

As provider networks align risk-sharing incentives, they must avoid partner risks that could pose a threat to the network. Partner risk results when actions taken by one or more partners in a network threaten to adversely affect other partners in the network. Such risk can arise from the way partners manage cost drivers under capitation or through passing risk to one another.

Capitation Fee↗