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Biomedical subjects

J K Ross

Publications and source records attributed to J K Ross.

At least 19 recordsLinked to original sources
PubMed1999

Atlas-axis facet asymmetry. Implications in manual palpation.

STUDY DESIGN: A basic study of six human cervical spines, documenting displacement with applied forces mimicking palpation. OBJECTIVES: To assess the issues of motion palpation of joint restrictions and the inferred link to disease. SUMMARY OF BACKGROUND DATA: Although several investigators have suggested that the issue of asymmetry and normal-abnormal function should be assessed, data are unavailable. METHODS: Atlas-axis specimens were harvested from six cadavers, cleaned of ligamentous and muscle tissue, and potted and secured with dental plaster. Forces (5-25 N) were applied along the mediolateral axis, and the corresponding displacement along three orthogonal axes were documented with infrared diodes and the Optotrak camera system (Northern Digital, Waterloo, Ontario, Canada). Specimen geometry and asymmetry were documented with plain radiographic film and a gimbal apparatus. RESULTS: Each of the six specimens displayed different behavior and differing degrees of asymmetry (e.g., facet inclination 17-35 degrees) so that each was analyzed as a case study. Asymmetrical and discontinuous force-displacement correlations were linked to anatomic asymmetry that appeared to be of natural occurrence. CONCLUSIONS: Asymmetrical joint geometry is common and causes asymmetrical joint dynamics. Thus, a clinician attempting to palpate vertebral motion would be misled by assuming that perceived restricted joint motion universally represented a finding potentially amenable to manipulation. For spine palpation to be a valid indicator for manipulation, the clinician applying it must first be able to differentiate between asymmetrical motion caused by vertebral fixation and that caused by asymmetrical joint anatomy.

Aged↗
PubMed1999

Tricuspid valve replacement: bioprostheses are preferable.

BACKGROUND AND AIM OF THE STUDY: Tricuspid valve replacement (TVR) is rarely undertaken, most surgeons preferring to use conservative tricuspid valve procedures. Thus, limited data are available in patients following TVR. The purpose of this study was to analyze the early and late results in 87 patients (52 tissue valves, 35 mechanical prostheses) who underwent TVR between January 1973 and September 1996. METHODS: The patient group comprised 74 (85%) females and 13 (15%) males; mean (+/- SD) age was 59.4 +/- 12.8 years; range: 15 to 81 years). Forty-four patients (51%) had undergone at least one previous cardiac operation. There were 19 (23%) isolated TVRs, 43 (49%) triple valve replacements, and 25 (29%) double valve replacements. Total cumulative follow up was 707 patient-years (pt-yr) (tissue valves 393 pt-yr, mechanical valves 314 pt-yr); mean follow up was 8.1 years (range: 0 to 23.6 years). RESULTS: The early (30-day) mortality rate was 10.3% (n = 9; tissue 7, mechanical 2, p = 0.28). Logistic regression identified prolonged cardiopulmonary bypass time (p <0.03) and advanced NYHA functional class (p <0.007) as risk factors for operative death. No risk factors were significant on multiple logistic regression analysis. Mean (+/- SEM) survival rate was 68 +/-5.3% (n = 50) at 5 years, 52 +/- 5.9% (n = 36) at 10 years, 35 +/- 6% (n = 20) at 15 years, and 16 +/- 5.3% (n = 7) at 20 years. Freedom from tricuspid valve reoperation at 5, 10 and 15 years was 93 +/- 3.3% (n = 46), 83 +/- 5.8% (n = 33) and 71 +/- 2.8% (n = 17) respectively. Eleven patients required tricuspid valve reoperation: six mechanical valves (five for prosthetic valve thrombosis and one for mechanical failure secondary to pannus ingrowth), and five tissue valves (two for prosthetic valve endocarditis and three for prosthetic valve degeneration). Freedom from reoperation at 5, 10 and 15 years for tissue prostheses was 97 +/- 2.5%, 89 +/- 6.3% and it was 70 +/- 12%, and 86 +/- 7.4%, 74 +/- 9.9% and 68 +/-11% for mechanical prostheses. The mechanical prostheses required reoperation earlier after the initial surgery. CONCLUSIONS: We recommend the use of a bioprosthesis in the tricuspid position because of its initial durability and low reoperation rate.

Adolescent↗
PubMed1999

Twenty-year follow-up of aortic valve replacement with antibiotic sterilized homografts in 200 patients.

The aim of this study was to determine long-term results from one unit of subcoronary homograft aortic valve replacement (AVR) using the same sterilization and preservation techniques in each case. Between 1973 and 1983, 200 patients underwent AVR using an unstented homograft previously sterilized in antibiotics and preserved at 4 degrees C. Surviving patients were monitored for a minimum of 15 years to the end of 1998. Mean age was 50.0+/-14 (1 standard deviation) years; 121 patients were men (60.5%). Mean patient follow-up time was 15.6+/-6.7 years, with a total follow-up time of 3,115 patient years. Follow-up was 95.6% complete. There were three early deaths (1.5%). At autopsy, the homograft was anatomically normal and in a satisfactory position. Kaplan-Meier survival, including early death, was 81.2%+/-2.8% (1 standard error) at 10 years, 68.1%+/-3.4% at 15 years, and 58.0%+/-3.7% at 20 years. Repeat AVR was undertaken in 74 patients, giving a freedom from reoperation for any reason of 86.5%+/-2.6%, 69.6%+/-3.8%, and 38.8%+/-5.3% at 10, 15, and 20 years, respectively. Freedom from structural valve degeneration at 10, 15, and 20 years was 81.1%+/-2.9%, 61.7%+/-3.9%, and 31.2%+/-4.7%, respectively. Freedom from endocarditis at 10, 15, and 20 years was 98.7%+/-0.9%, 96.0%+/-1.8%, and 94.6%,+/-2.3%, respectively. Homograft AVR with an antibiotic-sterilized valve stored at 4 degrees C and implanted in the subcoronary position offers low operative mortality and good long-term outcome for patients.

Antibiotic Prophylaxis↗
PubMed1996

Long-term results of valve replacement using antibiotic-sterilised homografts in the aortic position.

OBJECTIVE: Antibiotic-sterilised homograft valves stored at 4 degrees C have been implanted in the subcoronary position in this unit since 1973. This study was undertaken in order to assess the long-term function of these valves. METHODS: All 249 patients undergoing homograft aortic valve replacement (AVR) at the Wessex Cardiothoracic Centre between April 1973 and December 1994 were studied. Homograft valve sizes ranged from 15 mm to 28 mm internal diameter, 202 (81.1%) varying between 18 mm and 22 mm. The mean patient follow-up was 12.4 years with a total follow-up of 3096 patient-years. There were six early deaths (2.4%). RESULTS: On actuarial analysis, survival was 78.5+/-2.7% (1SE) at 10 years, 65.7+/-3.3% at 15 years and 55.0+/-3.9% at 20 years. The freedom from redo AVR was 87.9+/-2.4% at 10 years, 71.7 +/-3.8% at 15 years and 49.7+/-5.6% at 20 years. The freedom from structural degeneration was 85.6+/-2.5% at 10 years, 63.6+/-4.0% at 15 years and 41.9+/-6.4% at 20 years. On multivariate analysis the risk of valve failure was significantly higher in younger patients (P<0.0001) and in those who underwent aortic root tailoring (P = 0.024). The freedom from endocarditis was 98.4+/-0.9% at 10 years, 96.2+/-1.6% at 15 years and 95.1+/-1.9% at 20 years. Of the 249 patients, 218 had an isolated homograft AVR and were not anticoagulated. In this group there were two possible thromboembolic events. CONCLUSION: As well as the established haemodynamic benefits, this study has shown that homograft AVR with antibiotic-sterilised 4 degrees C stored homograft valves implanted in the subcoronary position, offers good long-term results.

Adolescent↗
PubMed1995

Biological valves beyond fifteen years: the Wessex experience.

Between 1975 and 1979, 443 biological valves (298 Carpentier-Edwards, 134 homograft, and 11 Hancock valves) were implanted in 415 patients (age, 16 to 77 years; mean, 59 years) with an operative mortality of 2.9%. Total follow-up was 4,248 patient-years. Overall event-free survival was 60% +/- 1.5% (standard deviation) at 10 years and 29% +/- 1.4% at 15 years. Ten-year and 15-year event-free survival were 72% +/- 3.4% and 41% +/- 3.3% for aortic homografts, 62% +/- 3% and 33% +/- 2.8% for isolated aortic xenografts, and 43% +/- 3.5% and 14% +/- 3.0% for isolated mitral xenografts. Freedom from structural valve degeneration was 87% +/- 1.3% and 63% +/- 2.5% for all patients at 10 and 15 years, respectively, 86% +/- 2.7% and 58% +/- 4.1% for aortic homografts, 93% +/- 1.8% and 76% +/- 5.1% for aortic xenografts, and 75% +/- 4.0% and 47% +/- 7.4% for mitral xenografts. Of the 110 remaining patients, echocardiography was performed in 61 patients (23 aortic xenograft, 24 aortic homograft, 9 mitral xenograft, and 5 tricuspid xenograft) between 14 and 17 years after implantation. An early diastolic murmur was heard in 57% of all aortic valve replacements (AVRs) 62.5% of homograft AVRs, and 52% of xenograft AVRs. Echocardiographically, aortic regurgitation was detected in 79%, 83%, and 74% of all AVRs, homografts, and xenografts, respectively. Aortic stenosis was present clinically in 11% of all AVRs, 4% of homograft AVRs, and 17% of xenograft AVRs.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1995

Night-shift work in Antarctica: sleep characteristics and bright light treatment.

Changes in sleep parameters during and after night-shift and the effects of bright white (2500-3000 1x) and dim red (> 500 1x) light treatment on re adaptation after night-shift during winter were studied in 14 men on the British Antarctic Survey Base of Halley (75 degrees south). Subjects kept daily sleep diaries and mood ratings from one week before to three weeks after night-shift and received either full-spectrum white or dim red light treatment from 1100 to 1300 h daily during the first week after night-shift. Plasma melatonin (for 24 h at the end of weeks 1, 2 and 4), and urinary 6-sulfatoxymelatonin (aMT6s, for 48 h weekly) were measured. A significant (MANOVA; p < 0.05) improvement in sleep was seen during night shift (latency and duration) and with bright light treatment (latency). Melatonin and aMT6s rhythms delayed by 7-8 h during night-shift. The white light group readapted slowly, apparently by phase delay, as assessed by aMT6s measurement. The red light group readapted slightly, but significantly (ANOVA, p < 0.01) faster than the white light group.

Adaptation, Psychological↗
PubMed1994

Dietary fiber values for various breads are higher using enzymatic analysis rather than detergent analysis.

OBJECTIVE: To compare the dietary fiber content of breads commonly eaten in Georgia, Michigan, Nevada, and Vermont. DESIGN: Dietary fiber content was determined according to neutral detergent fiber (NDF) plus pectin values and enzymatic gravimetric fiber values. White, whole-wheat, 100% stone-ground whole-wheat, cracked-wheat, and Roman Meal breads were analyzed for hemicellulose, cellulose, lignin, total NDF, pectin, and enzymatic gravimetric total fiber. STATISTICAL ANALYSES PERFORMED: Analysis of variance was used to determine significant F tests, and individual means were compared using Duncan's multiple range test. RESULTS: The 100% stone-ground whole-wheat bread had the most total fiber and fiber components followed by whole-wheat, Roman Meal, cracked-wheat, and white bread, except for pectin, of which Roman Meal had the most. The enzymatic gravimetric method of determining total fiber gave significantly (P < .0001) greater dietary fiber values than the values obtained by analyzing NDF plus pectin. These values ranged from 153% to 370% higher; however, there was a high degree of correlation (r = .95) between the methods. CONCLUSIONS: When recommending types of breads, dietitians should be aware of added ingredients that influence fiber values. When using published fiber values, dietitians should consider the technique used to quantify the fiber content.

Bread↗
PubMed1993

Late functional results after surgical closure of acquired ventricular septal defect.

To assess the longer term outlook for patients who have undergone surgery for acquired (postinfarction) ventricular septal defect, we interviewed and studied 60 survivors from a single regional cardiac center between 3 and 144 months after the operation. Including the patients who died within 1 month of the operation, the 5-, 10-, and 14-year survivals (with standard errors) were 69% (65% to 74%), 50% (44% to 57%), and 37% (27% to 46%). Eighty-two percent of patients were in New York Heart Association class I or II. Ten patients (17%) had a persisting but not hemodynamically significant ventricular septal defect. Mean left ventricular ejection fraction was reduced at 0.39 (standard deviation 0.15), but this did not correlate with either New York Heart Association class or exercise tolerance. Twenty-eight patients (47%) had asymptomatic arrhythmias (17 with ventricular premature beats). Angina and other medical problems were not prevalent.

Aged↗
PubMed1990

Reoperation for recurrent angina after aortocoronary bypass surgery.

One hundred reoperations were performed on 93 patients of a total of 2287 patients who underwent initial coronary artery bypass surgery (CABG) between September 1972 and August 1988. The mean age of the 84 males and 9 females was 55.5 years (range 31-75 years). All patients prior to reoperation had severe angina and were judged to be in NYHA class III or class IV. Late graft failure alone or in combination with progressive atherosclerosis accounted for more than 60% of the cases requiring reoperation. The early mortality for reoperation was 1% compared with 1.4% for initial CABG. Perioperative myocardial infarction was recorded as a complication in 3.2% of cases at initial operation compared with 1% at reoperation. Symptomatic improvement occurred in 89.1% of cases after reoperation and almost 60% became entirely asymptomatic (mean follow-up interval 17 months).

Adult↗
PubMed1990

Dietary and hormonal evaluation of men at different risks for prostate cancer: fiber intake, excretion, and composition, with in vitro evidence for an association between steroid hormones and specific fiber components.

Dietary fiber intake and fecal fiber excretion were investigated in 53 Seventh-day Adventist men: 18 nonvegetarians (NVs), 20 lactoovovegetarians (LOVs), and 15 vegans (Vs). Three-day composite diets and stools were analyzed for neutral detergent fiber (NDF), hemicellulose, cellulose, lignin, and pectin. In vitro binding of estrone (E1), estradiol-17 beta (E2), and testosterone (T) to a water-insoluble fiber fraction obtained from these diets was correlated with the intake of specific dietary fiber components. Vs consumed and excreted significantly more of all fiber components than did LOVs or NVs. LOVs consumed more of all fiber components (except cellulose) than did omnivores and excreted more NDF, hemicellulose, and cellulose. Dietary lignin was positively correlated with T binding in the V group. There were significant relationships for all groups combined between lignin and water-insoluble fiber binding of E1, E2, and T. Further study is needed to clarify relationships between fiber components, steroid-hormone metabolism, and risk of prostate cancer.

Adult↗
PubMed1990

Dietary and hormonal evaluation of men at different risks for prostate cancer: plasma and fecal hormone-nutrient interrelationships.

Relationships between dietary nutrients and plasma and fecal estrone, estradiol-17 beta, testosterone, and plasma prolactin concentrations were studied in young Seventh-day Adventist men: 18 nonvegetarians (NVs), 20 lactoovovegetarians (LOVs), and 15 vegans (V). Blood samples and 3-d dietary records were obtained. Contemporaneously collected diet composites and stool samples were analyzed for fiber. Vs and LOVs consumed significantly more fiber than did the omnivores, whereas NVs and LOVs consumed more saturated fatty acids than did Vs. Although plasma steroid-hormone status did not differ, Vs had significantly higher fecal estrogen concentrations than did NVs or LOVs. Plasma prolactin concentrations were significantly higher in NVs and LOVs than in Vs. Significant relationships were observed for the combined groups between dietary and fecal fiber components and fecal, but not plasma, steroid hormones. For the combined groups, prolactin concentrations were positively correlated with saturated fatty acid intake. Further research on the effects of dietary nutrients on endocrine homeostasis in other age groups is warranted.

Adult↗
PubMed1990

Surgical treatment for infarct-related ventricular septal defects. Improved early results combined with analysis of late functional status.

A total of 101 patients (mean age 64.9 years) underwent surgical correction of postinfarction ventricular septal defect at this institution over a 15-year period (1973 to 1988). The overall early mortality rate was 20.8%, although the most recent experience with 36 patients (January 1987 to October 1988) has seen this decline to 11.1%. Factors found to influence early death significantly, when analyzed univariately, were as follows: (1) site of infarction (anterior 12.1%, inferior 32.6%, p = 0.02); (2) time interval between infarction and operation (less than 1 week 34.1%, greater than 1 week 10.5%, p = 0.008); (3) cardiogenic shock (present 38.1%, absent 8.5%, p = 0.001). Nonsignificant variables included preoperative renal function, age, and concomitant coronary artery bypass, although older age (greater than 65 years) became significant when examined in a multivariate fashion. Of the 80 hospital survivors, eight were subsequently found to have a recurrent or residual defect necessitating reoperation, with survival in seven. Late follow-up is 99% complete and reveals an actuarial survival rate for 100 patients of 71.1% at 5 years (95% confidence interval 60.6 to 80.0), and 40.0% at 10 years (95% confidence interval 21.7 to 58.4). A significant recent change in policy of not using coronary angiography in patients with a ventricular septal defect caused by anterior wall infarction has not resulted in any increase in either the early mortality or in the late prevalence of angina. The functional status of 38 surviving patients has been analyzed by a graded treadmill exercise protocol, whereas left ventricular functional assessment was by nuclear scan with additional information on mitral valve function by echocardiogram. Color Doppler flow mapping has been used to determine the presence of a residual defect. Most late survivors have limited exercise tolerance related to both cardiac and noncardiac factors. Left ventricular function is moderately impaired (mean ejection fraction = 0.39). However, many patients are elderly and have adapted to their residual symptoms without significant changes in life-style.

Age Factors↗
PubMed1989

Surgical treatment of the ascending aorta. Fourteen years' experience with 83 patients.

Between December 1972 and December 1986, 83 patients with aneurysmal disease (n = 37) or dissection (n = 46) involving the ascending aorta underwent a variety of operations, including composite value-graft repairs (n = 39), separated replacements of the aortic valve and ascending aorta (n = 18), resuspension and graft replacement of the ascending aorta (n = 9), graft replacement of the ascending aorta only (n = 8), homograft root replacement (n = 3), aortic valve replacement with aortorrhaphy (n = 3), aotorrhaphy alone (n = 2), and use of a sutureless intraluminal prosthesis (n = 1). The inclusion method was used in nine patients. The hospital mortality rate was 10% for patients with annuloaortic ectasia, 21% (70% confidence interval 13% to 30%) for acute dissection, and 18% (70% confidence interval 14% to 22%) for the entire group. Logistic regression analysis showed age and cumulative bypass time to be significant for hospital death. The estimated 5-year survival rates are 69.5% +/- 7.2% and 67.0% +/- 9.0% and 10-year estimates are 34.6% +/- 10.6% and 61.4% +/- 9.8% for dissection and aneurysm, respectively. Patient survival was related to differing pathology and type of operation, and log-rank testing showed no differences at the 5% level. Attrition (17 late deaths) was mostly due to left ventricular dysfunction, myocardial infarction, or aneurysmal disease in ungrafted aorta. Actuarial freedom from thromboembolism in patients with prosthetic valves is 92.0% +/- 4.0% and 83.5% +/- 6.8% at 5 and 10 years. Freedom from all late graft and cardiac complications is 72.5% +/- 9.1% and 48.8% +/- 13.1% at 5 and 10 years for aneurysmal disease and 79.1% +/- 7.3% and 67.3% +/- 9.9% at 5 and 10 years for dissection. Reoperation in nine patients was required for pseudoaneurysms (n = 3), other aortic aneurysms (n = 3), persistent aortic regurgitation (n = 1), and obsolescent valve prosthesis (n = 2). Thus hospital mortality does not seem to be significantly related to the type of operation used for pathologic conditions of the ascending aorta unless cumulative bypass time exceeds about 2 hours. Many nonfatal late complications are associated with a prosthetic valve, but late death is due primarily to cardiac causes and residual disease in other parts of the aorta.

Aortic Dissection↗