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Biomedical subjects

B Gray

Publications and source records attributed to B Gray.

At least 91 records · Page 5Linked to original sources
PubMed1986

Supine exercise testing in the selection of suprainguinal versus infrainguinal bypass in patients with multisegmental arterial occlusive disease.

Proper assessment of aortoiliac disease requires hemodynamic evaluation during lower extremity vasodilatation. Two tests that meet this criterion, intraarterial papaverine injection and supine exercise of the lower extremities, were compared in 35 extremities of 27 patients. Hemodynamic improvement as measured postoperatively was used as the standard for comparison. Ergometer and papaverine tests were 100 percent and 94 percent accurate, respectively, had sensitivities of 100 percent and 100 percent, specificities of 100 percent and 93 percent, positive predictive values of 100 percent and 75 percent, and negative predictive values of 100 percent and 100 percent. The lower accuracy rate for the papaverine test was the result of two borderline (false-positive) examinations. The ergometer test is more accurate but less applicable than the papaverine test. Routine papaverine testing with adjunctive ergometer testing is a highly accurate method of assessing the hemodynamic significance of aortoiliac disease.

Aorta, Abdominal↗
PubMed1986

Effect of quantitated stenoses on arterial sound spectrum analysis.

Spectral analysis of carotid Doppler signals has been shown to be accurate in determining the degree of carotid artery stenosis when compared with arteriography. Since the Doppler angle and the amount of gain used during measurement may affect results, an in vitro study was performed measuring peak frequency, mode frequency, and percent window at various Doppler angles and gains to determine if these latter factors could affect results of the test. A spectrum analyzer with an 8 MHz continuous-wave Doppler probe was utilized. Seven cross-sectional area stenoses (0 to 100 percent) were applied to an undiseased bifurcated cadaver artery which was suspended in a saline bath and placed in a pulsatile circulatory system. At each stenosis, peak frequency, mode frequency, and percent window were measured at three Doppler angles (45 degrees, 60 degrees, and 75 degrees) at a constant gain and at three different gains (low, medium, and high) at a constant Doppler angle of 60 degrees. Arterial pressure was measured distal to the stenoses. Critical stenoses were present at greater than 82 percent area reduction. At a Doppler angle of 60 degrees and medium gain, correlation coefficients between percentage of stenosis and peak frequency, mode frequency, and percent window were 0.9520, 0.8369, and -0.9861, respectively. However, peak frequency and mode frequency actually decreased at stenotic areas of more than 82 percent and were similar to frequencies seen at stenotic areas of 61 percent. Peak frequency significantly decreased as Doppler angle increased, so there was an even greater overlap of peak frequency values at larger angles. Percent window did not appear to be affected by Doppler angle. At an angle of 60 degrees and different gains, there appeared to be very little overlap of percent window values between any stenoses. Peak frequency and mode frequency did not appear to be affected by gain. This study demonstrates an excellent correlation between percentage of stenosis and peak frequency and percent window. However, peak frequency was significantly affected by changes in Doppler angle and did not differentiate subcritical (61 percent) from critical (96 percent) stenoses. Percent window, however, was not significantly affected by Doppler angle or gain and was able to differentiate between all degrees of stenosis.

Arterial Occlusive Diseases↗
PubMed1986

The influence of topical anaesthetic agent at bronchoalveolar lavage upon cellular yield and identification and upon macrophage function.

The influence of cocaine and lignocaine as local anaesthetic agent upon the results obtained at bronchoalveolar lavage was investigated. No differences were found. A functional activity of macrophages was assessed when the cells were stored in lavage fluid. A time-dependent decrease occurred which was related to lack of nutrients rather than the anaesthetic concentration.

Bronchi↗
PubMed1986

Difference in structure between type b and nontypable Haemophilus influenzae populations.

The extent of chromosomal genetic variability and the genetic structure of Haemophilus influenzae populations was analyzed. A total of 119 isolates from humans in Göteborg, Sweden, and Birmingham, Ala., and 16 strains from a type culture collection were characterized for capsular type, biotype, outer membrane protein profile, and enzyme electrophoretic type (ET). The results of this study indicate that the bacteria identified as H. influenzae are a genetically extremely variable array of organisms. For the six enzymes studied, the estimated mean genetic diversity was 0.57 (approximately 20% higher than the corresponding estimate for Escherichia coli). Two lines of evidence indicate that despite its ability to recombine by transformation, H. influenzae maintains a largely clonal population structure. Although there is considerable potential for generating different genotypes, there were only 88 distinct ETs among the 135 strains, and isolates of the same ET and biotype were recovered at frequencies greater than would be anticipated at random. This evidence for a clonal population structure holds for uncapsulated as well as capsulated strains. However, these data also suggest that the stability of H. influenzae clones (clone persistence time) may be less than that of the nontransforming species E. coli. The ET data indicate that there is somewhat less variability among H. influenzae strains that express the same capsular antigens, biotype, and outer membrane proteins than among randomly chosen isolates. Nevertheless, there is substantial genetic variation among isolates within each of these classes and combinations thereof. There is also variation in these typing characteristics among strains of the same ET. These observations and those on genetic variability and population structures have implications for the characterization of H. influenzae isolates in clinical and epidemiological studies.

Bacterial Outer Membrane Proteins↗
PubMed1985

The role of carotid duplex scanning in surgical decision making.

Eighty-one patients suspected of having cerebrovascular disease had 157 carotid arterial systems studied by both duplex ultrasonography and contrast arteriography to better define the role of carotid duplex scanning in the surgical decision-making process. These studies were reviewed in a blinded fashion in conjunction with history and physical examination data by two surgeons, one operating on only symptomatic lesions, the other operating on both symptomatic and asymptomatic lesions. Results were analyzed to ascertain if there was agreement regarding decisions for carotid endarterectomy based on scan findings compared with decisions based on arteriographic findings. Scans were also compared with arteriograms and data were analyzed by decision matrix analysis. The accuracy of duplex scanning in relation to arteriography was 81% for detection of disease, 90% for the detection of ulceration, 83% for the detection of a critical stenosis, and 99% for the detection of total arterial occlusion. There was agreement between the two studies regarding the need for carotid surgery in 91% and 89% of carotid arteries, according to surgeons A and B, respectively. Regardless of the surgeons' indications for carotid endarterectomy, duplex ultrasonography provides sufficient information for proper surgical decision making in a high percentage of patients. The accuracy of duplex scanning and the risks of contrast arteriography suggest a possible future role for the routine use of duplex ultrasonography with selective utilization of arteriography in the surgical decision-making process in patients being evaluated for cerebrovascular occlusive disease.

Adult↗
PubMed1984

Is femoral pulse palpation accurate in assessing the hemodynamic significance of aortoiliac occlusive disease?

Palpation of the common femoral artery pulse has been the mainstay in the clinical assessment of the significance of aortoiliac disease for deciding whether to perform a suprainguinal versus an infrainguinal bypass. This study was performed to assess the accuracy of clinical pulse palpation in comparison to intraarterial pressure measurements of 31 common femoral arteries in 21 patients. Pulse palpation was graded as to the presence (abnormal) or absence (normal) of hemodynamically significant aortoiliac occlusive disease while at rest. A femorobrachial index of less than 0.9 was considered hemodynamically significant. Data were analyzed by decision matrix analysis. Results demonstrated pulse palpation to be 100 percent sensitive, 54 percent specific, and 61 percent accurate. The negative predictive value of normal pulse to palpation was 100 percent, but the positive predictive value for an abnormal pulse to palpation was only 29 percent. Even though pulse palpation should remain an integral part in the clinical assessment of the peripheral vascular tree, it should be used with caution in the clinical decision-making process.

Aortic Diseases↗
PubMed1984

Preferences for salivary odor cues by female hamsters.

There is a growing body of data which indicates that saliva may function as a chemosignal in mammals. The salience of this cue in hamsters is investigated. Twelve females were tested in a four-choice olfactorium to determine whether the subjects could differentiate and demonstrate a preference for salivary cues as a function of the dominance status of the stimulus donors and the subjects estrous state. Clear differences in responding were found for estrous as opposed to diestrous females. Estrous females detected and exhibited a preference for male stimuli on the basis of entry and approach measures. Subjects were also found to exhibit sniffing preferences for male odors and possible an avoidance of female odors relative to the saline control. Estrous females appeared to be unable to distinguish between dominant and subordinate males.

Animals↗
PubMed1984

Aortofemoral or femoropopliteal revascularization? A prospective evaluation of the papaverine test.

Proper selection of suprainguinal vs. infrainguinal arterial revascularization in patients with multilevel disease requires hemodynamic assessment. In such patients hemodynamic evaluation of the aortoiliac system cannot be made accurately with either arteriography or current noninvasive techniques. One hundred six lower extremities underwent preoperative triplane arteriography, measurement of Doppler-derived segmental blood pressures, measurement of common femoral intra-arterial pressure, and intra-arterial injection (30 mg) of the vasodilator papaverine hydrochloride prior to arterial bypass. Common femoral intra-arterial pressure was monitored continuously before and after papaverine injection. The resting femoral/brachial pressure index (FBI) and the maximum change in this index (% delta FBI) following papaverine injection were calculated. To be considered improved postoperatively, claudicants required an increase in treadmill walking time of greater than or equal to 50%, whereas patients operated on for limb salvage required an increase in the thigh/brachial pressure index (TBI) of greater than or equal to 0.15 for suprainguinal revascularizations and an increase of TBI to greater than or equal to 0.9 for infrainguinal revascularizations. In the first 41 extremities (phase I), receiver operator characteristic analysis revealed a % delta FBI greater than or equal to 15% to be optimal in the detection of hemodynamically significant aortoiliac disease. In phase II (65 limbs) this discriminant value for % delta FBI was assessed prospectively. In phase I, in which the choice of supra- vs. infrainguinal bypass was determined arteriographically, only 80% of the extremities were improved; in phase II, in which supra- vs. infrainguinal bypass was determined by the papaverine test, 98% of extremities were improved (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1983

Cigarette smoking and bladder cancer: an epidemiological inquiry in West Yorkshire.

Results are given of a case-control study on bladder cancer in West Yorkshire. The aim of the study was to assess what risks exist for cigarette smoking in the United Kingdom and also to investigate if a dose response effect was present. The study shows for the first time in the United Kingdom a positive but weak relationship between cigarette smoking and bladder cancer. Close examination of the data with regard to this effect shows that a complex set of relationships result when the quantity smoked and the period of smoking are taken into account. A dose response effect is weakly demonstrated when a medium quantity of cigarettes are smoked but it is not present at all in those who smoked most cigarettes for the longest periods. No risk appears to exist for those who have smoked only filter cigarettes. The results are contrasted with similar studies and the significance of the observations are discussed.

Age Factors↗
PubMed1983

Effect of vitamin A acid on homeostasis and differentiation of epidermal cells cultured on collagen.

Cultured guinea pig epidermal cells were treated with vitamin A acid (VA;2, 5, 10 micrograms/ml) and controlled by autoradiography and histochemical method. Cells attached to the bottom of the plates were counted and their number correlated with the number of cells sloughed off into the medium (A/D ratio). VA reduced the size of multilayered cell colonies, favoured cell spreading and accelerated confluence. It altered the mode of shedding since the cells sloughed off into the medium as isolated cells rather than cell complexes, as in untreated controls. It increased the A/D ratio in early cell cultures and decreased the A/D ratio in late cell culture. The higher the concentration of VA, the earlier and more prominent was the decrease of the A/D ratio. Low concentration of VA (2micrograms/ml) given once at seeding favoured the formation of keratohyalin and cornified envelopes whereas high concentration (5, 10micrograms/ml) given continuously prevented their formation and caused mucoid vacuolar degeneration of single cells. VA inhibited complete keratinization in all cases, but appeared to allow pre-keratinization, particularly at low concentrations. The results indicate that VA controls epidermal homeostasis in vitro by its influence on both proliferation and shedding. Its effect on the markers of differentiation is heterogeneous since it prevented keratinization in every case, but induced keratohyalin formation under certain conditions.

Animals↗
PubMed1983

Hemodynamic evaluation of the aortoiliac system based on pharmacologic vasodilatation.

Selection of the appropriate vascular reconstructive procedure in patients with multisegment disease requires the differentiation of aortoiliac from femoropopliteal occlusive disease and the detection of subcritical stenoses in the aortoiliac segment. Triplane arteriography and common femoral intra-arterial papaverine injection (30 mg) were done in 43 lower extremities in patients who subsequently had arterial bypass. The percent diameter stenosis was measured on the arteriograms and common femoral intra-arterial pressure was continuously monitored before and after papaverine injection. A resting femoral/brachial pressure index (FBI) was obtained and the percent decrease in this index (% delta FBI) was calculated using the maximum decrease in FBI following injection. Regression analysis revealed a significant correlation between % delta FBI and percent aortoiliac stenosis (r = 0.5446, P less than 0.005). In relation to clinical course, receiver-operator characteristic curve analysis revealed a % delta FBI of greater than or equal to 0.15 to be optimal in the detection of hemodynamically significant aortoiliac stenoses. When compared to clinical course, this % delta FBI was 88% sensitive, 100% specific, and 95% accurate. However, when analyzed with arteriography as the standard (50% stenosis), the same % delta FBI was only 70% sensitive, 100% specific, and 86% accurate. All limbs with a % delta FBI of 0.15 or greater improved following aortoiliac revascularization; 21% of these limbs had a normal preoperative resting FBI. No patient with a % delta FBI lower than 0.15 had improvement following aortoiliac revascularization. All limbs that had infrainguinal bypass had normal FBIs and % delta FBIs before bypass. After operation 90% of these limbs improved. Overall, this technique correctly predicted the clinical course in 95% of the limbs tested.

Aortic Diseases↗
PubMed1982

Increased penile perfusion and reversal of vasculogenic impotence following femoro-femoral bypass.

This study assessed the effect of femoro-femoral bypass on penile perfusion and impotence. Twelve patients with femoro-femoral grafts had Doppler pressure measurements and penile/brachial indices (PBI) recorded at both dorsal penile arteries, first with the graft open and then with the inflow portion of the graft temporarily occluded by manual external compression. Doppler pressure measurements and PBI did not change significantly in the dorsal penile artery on the donor (inflow) side of the graft when the graft was temporarily occluded. Patients who were potent both pre- and postoperatively (n = 5) had no significant change in pressure or PBI on the recipient (outflow) side of the graft with graft occlusion. In those patients who experienced reversal of impotence following bypass (n = 4) the mean dorsal penile artery pressure on the recipient side decreased from 101 mmHg with the graft open to 30 mmHg with the graft occluded (P less than 0.05). Review of arteriograms revealed that patients most likely to experience increases in penile perfusion have either (a) recipient side common iliac artery occlusion and a patent internal iliac system which is perfused in a retrograde fashion or (b) recipient side proximal internal iliac occlusion with well-developed collateral circulation between the profunda femoris and the distal internal iliac arterial systems. Femoro-femoral bypass can increase penile perfusion and alleviate vasculogenic impotence in selected patients.

Adult↗
PubMed1982

Identification of a major heparin-precipitable protein in human serum and its relationship to cystic fibrosis.

Heparin binding to serum proteins and their subsequent precipitation is reportedly increased in cystic fibrosis (CF). We have confirmed this finding for CF patients over the age of 12 [11.34 +/- 2.42 mg/ml precipitated protein for normals (n = 19) versus 17.46 +/- 4.60 mg/ml for CF patients (n = 37), P less than 0.001; 0.629 +/- 0.098 mg/ml precipitated heparin for normals versus 0.789 +/- 0.206 for CF patients, P less than 0.01]. We have also shown that patients with a variety of pulmonary diseases unrelated to CF do not show this effect. When the amounts of protein and heparin precipitated are compared with the amount of IgG found in the whole serum sample, the correlation coefficients (protein r = 0.77; heparin, 0.74; n = 81) are significant at a level of P less than 0.001. In addition, the report that young CF patients exhibit hypogammaglobulinemia prompted us to examine serum samples from CF patients and age-matched controls under the age of 12. No differences were found. To investigate the molecular basis for this effect, sera from patients with CF and from age-matched controls were precipitated with 50 mg% heparin at pH 5.57. Pellets resolubilized in 8 M urea were fractionated on DEAE-Sephadex and analyzed by double-immunodiffusion, SDS-PAGE, immunoelectrophoresis, and radial immunodiffusion. IgG constituted 55-56% of the eluted protein. When serum from all donors was fractionated by Staph A-Sepharose into IgG and non-IgG fractions, 85-89% of heparin precipitable protein was in the IgG fraction.

Adolescent↗
PubMed1982

Utility of wide and narrow blood pressure cuffs in the hemodynamic assessment of aortoiliac occlusive disease.

One hundred lower extremities were evaluated by measurement of common femoral intra-arterial pressure and high-thigh Doppler-derived segmental pressures using wide and narrow blood pressure cuffs to assess the accuracy of high-thigh pressures in the evaluation of aortoiliac disease. Sixty-four extremities were also studied by arteriography. The results were analyzed using the common femoral intra-arterial pressure as the standard. The accuracy was poor for both the wide (52%) and narrow (73%) cuff techniques. No significant differences between the two techniques were evident in regard to the incidence of false positive (wide cuff, 75%; narrow cuff, 65%) and false negative (wide cuff, 3%; narrow cuff, 8%) tests. Superficial femoral artery disease was found to be responsible for all false positive tests using the narrow cuff technique (20 of 20) and all but one of the false positive tests using the wide cuff technique (34 of 35). These data indicate that segmental high-thigh pressures are useful primarily as a screening technique (low false negative rate) to exclude hemodynamically significant aortoiliac occlusive disease at rest.

Aortic Diseases↗