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Biomedical subjects

C Bishop

Publications and source records attributed to C Bishop.

At least 37 records · Page 2Linked to original sources
PubMed1997

The alerting effects of short and long naps in narcoleptic, sleep deprived, and alert individuals.

Eleven narcoleptic patients and 22 age- and gender-matched normal controls participated in a study to determine the alerting effects of differing nap lengths. All narcoleptic patients had been previously diagnosed [mean sleep latency on the multiple sleep latency test (MSLT) < or = 5 minutes with two or more sleep-onset rapid eye movement periods (SOREMPs)]. Healthy, normal subjects with a mean sleep latency on the screening MSLT > or = 8 minutes were randomly assigned to one of two groups (i.e. sleep-deprived and alert). All subjects completed two experimental night and days with at least 5 days between sessions. On the evening prior to each experimental day, narcoleptic and alert subjects spent 8 hours in bed and sleep-deprived subjects spent 0 hours in bed. The following day, all subjects underwent one of two napping conditions, 15 or 120 minutes in bed. Both naps were terminated at noon. Every subject underwent both conditions and the order of conditions was counterbalanced. From 1215 to 1355 hours all subjects underwent a modified MSLT. At 1500 hours, the subjects had a 1-hour nap. The results showed that the 120-minute nap condition was more beneficial than the 15-minute nap. Narcoleptic and sleep deprived subjects were shown to have comparable levels of sleepiness on the modified MSLT. However, a differential response pattern on their latency to sleep was noted on the 1-hour nap. Sleep-deprived subjects were shown to be differentially more alert following a 120-minute nap opportunity. In contrast, for narcoleptic patients the beneficial effects of the nap were lost when tested 3 hours later. These results show that narcoleptic patients benefit from a longer nap but that these benefits are short-lived.

Adult↗
PubMed1997

The sleep/wake habits of patients diagnosed as having obstructive sleep apnea.

STUDY OBJECTIVE: To determine the sleep/wake habits of patients diagnosed as having obstructive sleep apnea (ie, respiratory event index [REI] > or = 5). DESIGN: Case series with prospective data collection to determine the relationship among sleepiness, REI, and sleep/wake habits. Patients were grouped according to their multiple sleep latency test (MSLT) results (< or = 5 and > 5) and REI (mild REI < or = 20; moderate REI > 20 but < or = 60; and severe REI > 60). SETTING: An American Sleep Disorders Association-accredited sleep laboratory. PATIENTS: Three hundred ninety (325 male, 65 female) consecutive patients seen between June 1993 and January 1995 for evaluation of sleep apnea. This included a sleep, medical, and psychiatric evaluation followed by a physical examination. Sleep histories and sleep/wake habits were recorded by a physician trained in sleep medicine. Polysomnographic evaluation consisted of a nocturnal clinical polysomnogram (CPSG) and an MSLT on the following day. Of 390 patients, 268 completed polysomnographic evaluation (CPSG and MSLT). MEASUREMENTS AND RESULTS: Sleepy (MSLT < or = 5) patients with mild (REI < or = 20) and moderate apnea (REI > 20 < or = 60) reported spending significantly less time in bed than sleepy patients with severe apnea (REI > 60). Those with severe apnea (REI > 60) reported napping significantly more and experienced a more severe disruption of their routine daily activities because of sleepiness when compared with mild and moderate OSA patients. CONCLUSIONS: These data suggest that sleep habits have an important modulatory effect on the level of sleepiness and this effect is lost as the severity of sleep-disordered breathing increases.

Aging↗
PubMed1997

The effects of predetermined payment rates for Medicare home healthcare.

OBJECTIVE: To assess the effects of an alternative method of paying home health agencies for services to Medicare beneficiaries, based on a demonstration program. DATA SOURCES/STUDY SETTING: Primary and secondary data collected on participating home health agencies in five states and their patients during the three-year demonstration period. Primary data included patient surveys at discharge and six months later, and two rounds of interviews with executive staff of the agencies. Secondary data included agencies' Medicare cost reports, quality assurance reviews, Medicare claims data, demonstration claims data, demonstration patient intake forms, and plan of treatment forms. STUDY DESIGN: The 47 agencies volunteering to participate in the demonstration were each randomly assigned to the treatment or control group. Treatment group agencies were paid a predetermined rate based on their inflation-adjusted cost per visit during the year preceding the demonstration; control group agencies were paid under Medicare's conventional cost reimbursement method. Demonstration impacts were estimated by comparing outcomes for the two groups of agencies and their respective patients, using regression models to control for any remaining differences. PRINCIPAL FINDINGS: Agencies paid under prospective rate setting were slightly better at holding per-visit cost increases below inflation than were control group agencies. The change in payment method had no effect on agencies' volume of Medicare visits or quality of care, nor on patients' use of Medicare services or other formal or informal care services. CONCLUSION: Changing from cost-based reimbursement to predetermined payment rates for Medicare home healthcare visits would not lead to large savings for the Medicare program, but would not increase costs to Medicare or adversely affect patients or their caregivers.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1997

A hidden complication of out-patient arteriography.

Rapid progression of arterial disease may occur between out-patient diagnostic arteriography and therapeutic angioplasty. We have studied the incidence of this complication in our institution. Sixty-seven consecutive out-patient arteriograms were assessed. Thirty-four patients were re-admitted for angioplasty within a median interval of 4 weeks (range 5 days-3 months). We compared immediate pre-angioplasty arteriograms with the out-patient images. Twenty-five pairs of films showed disease progression. Three patients showed new disease, one remote from the site of the arterial lesion and two in the opposite limb. Six patients showed marked progression of the original disease. The policy of delayed treatment after out-patient arteriography may require reconsideration in the light of our complication rate of 18%.

Aged↗
PubMed1996

Nocturnal sleep latencies among alert, alert-deprived and sleepy subjects.

Twenty-seven healthy, asymptomatic subjects participated in a study to determine repeated nocturnal sleep latencies as a function of level of daytime sleepiness. Subjects were screened polysomnographically and were determined to be free of any sleep pathology. Nine subjects had a screening multiple sleep latency test (MSLT) of < or = 5 min and 18 had a MSLT of > or = 10 min. Subjects were assigned to 3 groups, sleepy (MSLT < or = 5 min), alert, and alert sleep-deprived groups (MSLT > or = 10 min). Repeated nocturnal latencies to sleep were determined at 2300, 0110, 0310 and 0510 h on 2 nights with at least 5 days between nights. The results showed a main effect of group on the repeated nocturnal sleep latencies. Post-hoc tests demonstrated longer repeated nocturnal latencies among alert subjects compared to the sleepy and alert sleep-deprived subjects. The latter two groups had comparable sleep latencies. A significant main effect of time of night was also shown. The 0510 h latency was significantly shorter than the latencies at 2300 and 0110 h. The 0310 h latency was significantly shorter than the 0110 h latency and comparable to the 2300 and 0510 h latency. Significant correlations were found between daytime MSLT, repeated nocturnal sleep latencies, and nocturnal sleep time. These results show systematic differences in repeated nocturnal sleep latencies among sleep and alert subjects and extend the already described characteristics of these subjects by comparing them to a group of alert sleep-deprived subjects.

Adult↗
PubMed1996

The significance of increased 111indium platelet accumulation at post-angioplasty sites.

We assessed prospectively the significance of 111indium labelled platelet accumulation following angioplasty procedures in 12 patients (9 femoral angioplasties (2 laser, 1 atherectomy) and 3 iliac stents). Autologous 111indium labelled platelets were re-injected immediately after angioplasty. Radioactivity was measured over treated and reference sites, by single probe and gamma camera, and expressed as a radioactivity ratio (RR). All patients had duplex ultrasound assessment and occlusions were confirmed by arteriography. RR was always raised after angioplasty. Three patients who had acute occlusions showed markedly raised average RRs (significant at 99% ANOVA). RR was not raised after laser assisted angioplasty, however, our numbers were small. 111Indium platelet radioactivity did not predict subsequent occlusion after angioplasty but effectively detected existing acute post-angioplasty occlusions.

Angiography↗
PubMed1996

Non-invasive assessment of arterial stenoses in angioplasty surveillance: a comparison with angiography.

OBJECTIVES: Comparison of non-invasive arterial measurements with angiography and their use for angioplasty surveillance. DESIGN: Prospective assessments of arterial stenoses in patients undergoing angioplasty in a 9 month surveillance period. MATERIALS: Fifty consecutive patients undergoing angioplasty. METHODS: (i) One hundred and thirty-one sets of clinical assessments, ankle brachial Doppler pressure indices and colour Duplex velocities and diameters were compared to time-matched angiographic diameter stenosis. (ii) Fifty patients undergoing femoropopliteal angioplasty (32 stenoses and 18 occlusions) were studied with ankle branchial Doppler pressure indices and colour Duplex and angiography during a 9 month surveillance period. RESULTS: (i) Symptoms, pulses, resting ABPI, and exercise ABPI showed no useful correlation with angiography. Duplex velocity ratio and Duplex diameters showed correlation and agreement with angiography respectively. (ii) On surveillance, restenosis was universal but not always clinically significant. Angioplasty caused a rapid improvement in ABPI and imaging studies which worsened at later times. ABPI did not predict clinical failure however, Duplex and angiography predicted all clinical failures. CONCLUSIONS: Restenosis should be assessed with imaging of the angioplasty site during angioplasty surveillance.

Adult↗
PubMed1996

Inhibition of intimal hyperplasia in balloon injured arteries with adjunctive phthalocyanine sensitised photodynamic therapy.

OBJECTIVES: We investigated the effects of Photodynamic therapy (PDT) using Aluminium disulphonated phthalocyanine (AlS2Pc) on experimental intimal hyperplasia (FCIH). MATERIALS AND METHODS: (a) Pharmacokinetics: Normal rats were injected with Als2Pc and carotid artery fluorescence was measured. (b) Normal artery PDT: Sensitised rats underwent carotid artery laser irradiation (50J/cm2, 675nm) and were assessed after 3 and 14 days and 1-6 months. (c) PDT: Rats underwent standard carotid artery balloon injury immediately prior to PDT and arteries were assessed at 2 to 26 weeks, together with laser, AlS2Pc, and untreated controls. CHIEF OUTCOME MEASURES: (a) Fluorescence intensity in different arterial layers. (b) Medial smooth muscle cell counts per high power field (light microscopic). (c) Percentage amount of FCIH (area of intimal hyperplasia) as a ratio of the IEL (area enclosed by the internal elastic lamina). RESULTS: (a) AlS2Pc fluorescence intensity increased with increasing dosage, with maximal fluorescence in the arterial media at 30 min. (b) PDT produced medial cell depletion at 3 days and persisted over 6 months without loss of vessel integrity. (c) PDT completely inhibited FCIH at 2 and 4 weeks. This was partial at 6 to 26 weeks (51% of untreated level). PDT inhibition of FCIH was significantly greater than in any of the control groups. p < 0.0001. Mann-Whitney Test. CONCLUSION: Adjunctive AlS2Pc sensitised photodynamic therapy inhibits experimental intimal hyperplasia, by causing medial smooth muscle cell depletion. This offers a new approach to the management of angioplasty restenosis in patients.

Angioplasty, Balloon↗
PubMed1996

Auditory awakening thresholds in sleepy and alert individuals.

Twenty-seven healthy men and women with regular sleep-wake habits (and no habitual napping) participated in a study to determine the relation between auditory awakening thresholds (AAT) and multiple sleep latency test (MSLT) scores. Subjects were free of any sleep complaints and were screened polysomnographically. Nine subjects had a screening MSLT of < or = 5 minutes (sleepy group), and 18 subjects had an MSLT of > or = 10 minutes. Subjects were assigned to three groups: a sleepy group, alert group and an alert sleep-deprived group. Subjects underwent 2 nights of AAT testing with at least 5 days in between each study night. AATs were determined at 0100, 0300, 0500 and 0730 hours. There were a total of 209 available AAT determinations, with a comparable number of trials across the groups. Because 68% of AAT determinations were done out of stage 2 non-rapid eye movement (NREM) sleep, the thrust of the analysis was based on the results of this stage of sleep. The AATs were averaged across the two experimental nights. Trials 1 and 2 (first half of the night) and 3 and 4 (second half of the night) were averaged for each subject. There was no main effect of group on AATs. However, there was a significant main effect of time and a significant group by time interaction. The former indicated an overall decline in AATs across the night. More importantly, the three groups had comparable AAT levels during the first half of the night:. Sleepy and alert-deprived subjects, however, failed to show a decline in AATs, whereas the alert group showed a significant decline in the second half of the night. This differential rate of decline in AATs is suggested to be related to the differences in sleep homeostasis among alert and sleepy individuals.

Acoustic Stimulation↗
PubMed1996

The frequency of multiple sleep onset REM periods among subjects with no excessive daytime sleepiness.

The multiple sleep latency test (MSLT) is a valuable tool in the assessment of excessive daytime sleepiness (EDS). Additionally, multiple sleep onset rapid eye movement periods (SOREMPs) are a frequent occurrence in patients with narcolepsy. To date, however, few studies have evaluated the frequency of SOREMPs in a population of healthy control subjects. Subjects participating in a variety of sleep studies were screened with a nocturnal clinical polysomnogram, followed by the MSLT. Subjects were required to be drug free and have no sleep-related symptoms or medical or psychiatric conditions. Of the 139 subjects who were screened, 24 (17%) had two or more SOREMPs. These individuals were more likely to be male, younger, and sleepier than those with one or zero SOREMPs. The etiology of two or more SOREMPs in healthy controls was not apparent from the clinical or polysomnographic evaluation. Although it is possible that these findings are early signs of narcolepsy, subjects reported being free of any sleep-related complaints. Further investigations into the determinants of multiple SOREMPs and their reliability among asymptomatic populations are warranted.

Adult↗
PubMed1995

Photodynamic therapy of normal and balloon-injured rat carotid arteries using 5-amino-levulinic acid.

BACKGROUND: Although the management of atherosclerotic disease by the use of balloon angioplasty is widespread, the treatment is limited by restenosis in 30% to 50% of cases. Fibrocellular intimal hyperplasia, the main cause of restenosis, arises from proliferation and migration of medial smooth muscle cells (SMC) into the intimal layer. Factors leading to intimal hyperplasia are incompletely understood, and drugs have universally failed to influence clinical restenosis. Photodynamic therapy (PDT), the light activation of photosensitizing drugs to generate cytotoxic mediators, may have potential as prophylaxis for intimal hyperplasia. 5-Amino-levulinic acid-induced protoporphyrin IX (ALA-PPIX), a naturally occurring porphyrin precursor, and its product, -PPIX, offers a novel method of sensitization for PDT. We have investigated the pharmacokinetics of ALA in arteries and the effects of ALA-PPIX-sensitized PDT on normal and balloon-injured arteries. METHODS AND RESULTS: ALA (20 to 200 mg/kg) was injected into healthy rats, and PPIX fluorescence was measured in the carotid arteries. In a second group of rats, the exposed carotid artery was laser illuminated (50 J/cm2, 630 nm) 30 to 90 minutes after sensitization. Three and 14 days after PDT, histological sections from treated arteries were analyzed by light microscopy. Subsequently, two new groups of rats underwent PDT (ALA, 100 mg/kg; laser, 50 J/cm2, 630 nm [at 60 to 90 minutes]). The left carotid arteries underwent balloon angioplasty by intraluminal passage of a Fogarty FG2 catheter immediately before irradiation. These rats were killed at 14 and 28 days together with laser-only, ALA-only, and untreated control rats. The arteries were perfusion-fixed in vivo. ALA-PPIX induced arterial media fluorescence in a dose-dependent manner. In the normal arteries, PDT produced a dose-dependent cellular depletion in the treated arterial segment at 3 days, and this was complete with 100 and 200 mg/kg of ALA. At 14 days, the media remained acellular, although the endothelial lining had regenerated. In the balloon-injured arteries, PDT produced complete inhibition of intimal hyperplasia at both 14 and 28 days (0%). This was significantly greater than that produced by any of the control rats (34% to 69% and 37% to 66% at the two times, respectively). Significance was at 99% using ANOVA and Fisher's PLSD test. No hemorrhage, thrombosis, or aneurysm formation was seen. CONCLUSIONS: ALA-PPIX-sensitized PDT applied at the time of angioplasty effectively inhibits experimental intimal hyperplasia development in rats. This may offer a new approach to the management of angioplasty restenosis in patients.

Aminolevulinic Acid↗
PubMed1995

Aortic root replacement and extraanatomic bypass for interrupted aortic arch in an adult.

We describe an unusual case of interrupted aortic arch, aneurysmal ascending aorta, and aortic regurgitation in a 24-year-old man. He presented with general malaise, weakness of his legs, and hypertension. A single-stage operation was performed in which the aortic root was replaced with concomitant extraanatomic bypass of the interrupted segment of the aortic arch. He made a full recovery and has returned to work.

Adult↗
PubMed1995

A systematic approach to health surveillance in the workplace.

This paper reviews the range of health surveillance activities which can be utilized in the workplace by occupational health professionals for assessing fitness for work and contributing to the prevention of occupational illness and promotion of good health. The systematic approach described categorizes health surveillance procedures into occupational or non-occupational, risk-based or unfocused, and as primary, secondary or tertiary preventive measures. All categories of health surveillance are currently being practised to some extent, but the type of surveillance may not match the needs of the workplace in some situation. In order to aid health professionals in deciding which procedures should be implemented, recommendations based on an assessment of health risks are made. The key proposal is to establish a minimum level of periodic health surveillance for all workers based on a targeted lifestyle health risk assessment and a structured health questionnaire. Additional procedures can then be added sequentially as appropriate to manage any health risks in the workplace. The role of the unfocused periodic general medical examination is discussed in the context of the systematic approach and allows occupational professionals to critically appraise its usefulness.

Health Promotion↗
PubMed1995

Physiological modelling of oxygen consumption in birds during flight

This study combines data on changes in cardiovascular variables with body mass (Mb) and with exercise intensity to model the oxygen supply available to birds during flight. Its main purpose is to provide a framework for identifying the factors involved in limiting aerobic power input to birds during flight and to suggest which cardiovascular variables are the most likely to have been influenced by natural selection when considering both allometric and adaptive variation. It is argued that natural selection has acted on heart rate (fh) and cardiac stroke volume (Vs), so that the difference in the arteriovenous oxygen content (CaO2-Cv¯O2) in birds, both at rest and during flight, is independent of Mb. Therefore, the Mb exponent for oxygen consumption (V(dot)O2) during flight can be estimated from measurements of heart rate and stroke volume. Stroke volume is likely to be directly proportional to heart mass (Mh) and, using empirical data, values for the Mb coefficients and exponents of various cardiovascular variables are estimated. It is concluded that, as found for mammals, fh is the main adaptive variable when considering allometric variation, although Mh also shows a slight scaling effect. Relative Mh is likely to be the most important when considering adaptive specialisations. The Fick equation may be represented as: (V(dot)O2)Mbz = (fh)Mbw x (Vs)Mbx x (CaO2 - Cv¯O2)Mby , where w, x, y, z are the body mass exponents for each variable and the terms in parentheses represent the Mb coefficients. Utilising this formula and data from the literature, the scaling of minimum V(dot)O2 during flight for bird species with a 'high aerobic capacity' (excluding hummingbirds) is calculated to be: 166Mb0.77&plusmn;0.09 = 574Mb-0.19&plusmn;0.02 x 3.48Mb0.96&plusmn;0.02 x 0.083Mb0.00&plusmn;0.05 , and for hummingbirds (considered separately owing to their unique wing kinematics) it is: 314Mb0.90&plusmn;0.22 = 617Mb-0.10&plusmn;0.06 x 6.13Mb1.00&plusmn;0.11 x 0.083Mb0.00&plusmn;0.05 . These results are largely dependent on the cardiovascular values obtained from pigeons flying near to the minimum power speed of 10 m s-1, but would appear to provide realistic values. Both the measured and the estimated V(dot)O2 for hummingbirds appear to scale with a larger Mb exponent than that for all other birds, and it is suggested that this is as a result of the larger Mb exponent for flight muscle mass as the larger species of hummingbirds try to maintain hovering performance. It is proposed that estimated V(dot)O2 for birds during flight, which is based on Mh in combination with estimates of fh and CaO2-Cv¯O2, gives an indirect measure of relative aerobic power input and, when corrected for the estimated scaling influences of the mechano-chemical conversion efficiency and lift generation with respect to Mb, may be a useful indicator of the relative capacity of the muscle to sustain power output and lift production during flight.

Journal Article↗
PubMed1995

Cystic fibrosis mutations among African Americans in the southeastern United States.

Since the cloning of the cystic fibrosis (CF) gene and the identification of delta F508, the most common CF mutation, screening the general population for CF has been vigorously debated. Adding to the controversy is the question of whether screening should be offered to African Americans, whose incidence of CF (1/17,000) is much lower than that of whites (1/2500). We tested for five common mutations (delta F508, G551D, G542X, R553X, and N1303K) in order to determine the frequency of common mutations in African Americans with CF from the southeastern United States. delta F508 was found on 50% of CF chromosomes; 46% of CF mutations were undetermined mutations. Our data indicate that at the current detection rate, the sensitivity of CF screening in African Americans would be appreciably lower than that of whites, and thus their inclusion in screening programs probably would not be warranted.

Black People↗