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Biomedical subjects

E A Ross

Publications and source records attributed to E A Ross.

At least 37 records · Page 2Linked to original sources
PubMed1995

Removal of iron dextran by hemodialysis: an in vitro study.

Intravenous iron dextran is frequently prescribed for iron-deficient hemodialysis patients, a practice that has increased during the erythropoietin era. Whether iron dextran is removed by hemodialysis has been a concern, especially for high permeability membranes. The purpose of this in vitro study was to measure iron dextran clearance by nine different hemodialyzers (Fresenius F3, F8, and F80B; Baxter CF25, CA150, CA210, and CT190; Toray BK2.1P; and Hospal Filtral 16) representing six types of membranes (polysulfone, cuprophane, cellulose acetate, cellulose triacetate, polymethylmethacrylate, and polyacrylonitrile) and including membranes considered high efficiency and high flux. Clearances were assessed using a closed-loop, fixed-volume reservoir model. Absolute drug removal also was determined over the 30-minute experiments. Iron dextran clearance did not exceed 25 mL/min, and clearances also were minimal after a single automated reuse with glutaraldehyde sterilant. A maximum of 8% of iron dextran was removed during the experiment. We conclude that iron dextran clearance by the nine hemodialyzers studied was small or too low to be detected in this sensitive in vitro dialysis system and that adjusting dosing schedules is not needed.

Hemodialysis Solutions↗
PubMed1995

Polymorphisms within the atrial natriuretic peptide gene in essential hypertension.

OBJECTIVE: To investigate polymorphisms in the atrial natriuretic peptide gene of African Americans at intron two (Hpall) and exon three (Scal). RESULTS: The allele frequency of the Hpall mutation was 25% in the hypertensive group (n =60) compared with only 3.4% in normotensive individuals (n = 44, P < 0.0001). The genotype heterozygote for the present mutation was much more common among those with hypertension (50 versus 6.8%, P < 0.0001). The groups were no different for the Scal site alone, although the two mutations were present together more often in the hypertensive group. The Hpall mutation was associated with hypertension in this typically salt-sensitive population.

Adult↗
PubMed1995

Polymorphism of the angiotensin I converting enzyme gene in essential hypertensive patients.

Insertion/deletion (I/D) polymorphism of the angiotensin I converting enzyme (ACE) gene has been associated with ischemic heart disease and hypertension. The D allele reportedly correlates with myocardial infarction and it has been suggested that it may serve as the basis of population-based risk assessment. Similarly, determining whether there is an ACE allele pattern associated with hypertension could be useful in developing screening strategies. Previous reports have not shown consistent findings in Caucasian and Japanese population groups, some having a predominance of the I allele. Although African Americans have the highest prevalence of hypertension in the world, their ACE gene polymorphism frequencies have not been clearly defined. We studied the allele and genotype frequencies in this group, consisting of 133 essential hypertensive subjects, and compared their findings with those reported from normotensive African Americans and from other racial groups. The black patients had a different allele distribution than the other populations in that the D was more common than the I allele, occurring at a rate of 59.7%. The most common genotype was DD and it was present in 42.5% of the hypertensive subjects in contrast to the ID genotype which was the most commonly reported genotype in normotensive individuals. The genotype pattern (frequencies of II, ID, DD) was significantly different (p < 0.005, 2 df) from Japanese and Caucasian (Scotland and Australia) populations. There was no common allele or genotype distribution amongst these diverse hypertensive groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Elevated plasma lipoprotein(a) levels and hypoalbuminemia in peritoneal dialysis patients.

Plasma lipoprotein(a), Lp(a), is strongly and independently associated with atherosclerosis, and levels are elevated in hemodialysis (HD) patients and in some studies of those on peritoneal dialysis (PD). We hypothesized that protein losses and hypoalbuminemia could stimulate hepatic Lp(a) synthesis, and this effect would be accentuated in PD patients with malnutrition. The PD subjects (n = 24) had higher plasma Lp(a) levels than those (n = 10) on HD (median 34.4 vs 21.0 mg/dl, p < 0.05), and values exceed normal in 62.5% vs 20% of the subjects (p < 0.03), respectively. The serum albumin levels inversely correlated with concentrations of Lp(a) and apolipoprotein B, as well as the apolipoprotein B/AI ratio. In conclusion, plasma Lp(a) concentrations are frequently elevated in PD as well as HD patients. Measuring Lp(a) levels is useful in identifying patients at increased atherogenic risk, which may not be reflected in routine lipid profiles. The negative correlation between plasma Lp(a) and albumin levels suggests that the latter may be linked pathophysiologically to hepatic Lp(a) production. The association of hypoalbuminemia with higher Lp(a) values is of particular concern because malnutrition frequently occurs in PD patients.

Adult↗
PubMed1994

Mast cell phagocytosis of FimH-expressing enterobacteria.

Most studies of mast cells have been directed at their role in the pathophysiology of IgE-mediated allergic reactions with little recognition of their participation in bacterial infections. We report that mast cells can specifically bind FimH, a mannose-binding subunit on type 1 fimbriae expressed by Escherichia coli and other enterobacteria. This interaction triggers mast cell phagocytosis and killing of the bacteria within vacuoles and through the release of superoxide anions. Also, in view of the fact that mast cells have the capacity to release inflammatory mediators and are particularly abundant in the skin, mucosal surfaces, and around blood vessels, we suggest that these cells play an important role in host defense against microbial infection.

Adhesins, Escherichia coli↗
PubMed1994

Receptivity of African-American men to prostate cancer screening.

OBJECTIVE: The lifetime risk of prostate cancer among African-American men is two times higher than that of white men. Mortality from the disease is almost three times greater in African-Americans than in whites. This study assesses the receptivity of older (fifty to seventy-four years of age) African-American men (n = 86) in Chicago to periodic (annual and semiannual) prostate cancer screening. METHODS: A telephone survey conducted in January and February 1993, was used to collect data on subject sociodemographic background and medical history and to gather information on knowledge, attitudes, and beliefs about prostate cancer and screening. Univariate and multivariate analyses were carried out to identify factors associated with subject receptivity to annual and semiannual screening. RESULTS: Logistic regression analyses revealed that receptivity to annual and semiannual (every six months) examination is strongly associated with the degree to which screening is perceived as a salient and coherent (i.e., important, effective, and convenient) preventive health behavior. An additional factor independently associated with willingness to go through semiannual screening was subjects' awareness that African-American men are at increased risk for prostate cancer compared to white men. CONCLUSIONS: Findings from this study suggest that African-American men are willing to undergo prostate screening and are more receptive to annual than semiannual screening. Participation in screening may be facilitated by the provision of health education messages that emphasize the salience and coherence of early detection and elevated population risk.

Black or African American↗
PubMed1994

Analysis of two variants of the angiotensinogen gene in essential hypertensive African-Americans.

Two mutations (T174M and M235T) in the angiotensinogen gene have been reported to be associated with hypertension. This study examines the frequency of these mutations among African-American hypertensive patients (n = 109). The allele frequency of the T174M mutation was 4.6% and the frequency of the M235T mutation was 86.7%. The genotypic frequencies agreed with the conditioned Hardy-Weinberg predictions based on allele frequencies. The homozygote wild-type genotype at the T174 site was more frequent than the mutation and occurred at a rate of 91.7%. Conversely, the homozygote for the mutation at the M235 site was more frequent and occurred at a rate of 75.2%. Mutation frequencies for T174M and M235T in this African-American population differ from those previously reported from a white hypertensive population (P = .0058 and P = .0001, respectively). In summary, the representation of the angiotensinogen allele frequencies differ among hypertensive populations.

Adult↗
PubMed1994

Frequencies of the angiotensinogen gene and angiotensin I converting enzyme (ACE) gene polymorphisms in African Americans.

The purpose of the present study was to characterize three polymorphisms within the renin-angiotensin-aldosterone system in an African American population. A new mispairing primer polymerase chain reaction (PCR) was developed to identify two polymorphisms (T174M, M235T) in the angiotensinogen gene. A previously described PCR method was used to identify an insertion (I)/deletion (D) polymorphism in the angiotensin I converting enzyme (ACE) gene. Forty healthy, unrelated African Americans participated. The T174M mutation occurs less frequently (5.0%) than the M235T mutation (87.5%). The ACE D polymorphism occurs at a higher rate (70%) than the I. The data reveals that the two angiotensinogen mutation allele frequencies occur at similar rates regardless of the ACE gene allele. There appears to be no association between the mutations, indicating the loci are not linked.

Alleles↗
PubMed1993

Increased reverse cholesterol transport in athletes.

Proposed mechanisms for the cardioprotective benefits of exercise include decreased lipid deposition and increased reverse cholesterol transport (RCT). RCT involves the efflux of tissue free cholesterol into high-density lipoprotein (HDL) particles, esterification by lecithin:cholesterol acyltransferase (LCAT), transfer to other lipoproteins by cholesterol ester transfer proteins (CETP), and liver excretion. We tested the hypothesis that RCT is enhanced in athletes and that this can occur without large increases in plasma HDL cholesterol (HDL-C) mass levels. Fasting venous blood was drawn from 13 sedentary men and 11 athletes exercising at the rate of 5,185 +/- 501 kcal/wk. Compared with controls, athletes had similar age, body mass index (BMI), HDL-C (P > .1) and apolipoprotein (apo) A-1 (P > .5) levels, and lower low-density lipoprotein cholesterol (LDL-C) (P < .05) and apo B (P < .03) levels. The net mass of free cholesterol transported (NMCT) out of cultured human fibroblasts into the athletes' serum was greater than that for controls (25.5 +/- 8.0 v 7.1 +/- 2.6 micrograms/mL/h, P = .048). The efflux component of this transport correlated with HDL-C and apo A-1 levels and was similar between groups (P = .24), suggesting that athletes' antiatherogenic NMCT findings were due to decreased cholesterol influx into the cells. Athletes had increased plasma LCAT (20.3 +/- 2.1 v 13.9 +/- 1.5 micrograms/mL/h, P = .028) and CETP activities (69.7 +/- 4.5 v 21.5 +/- 4.8%/mL/h, P < .001). The NMCT positively correlated with CETP and LCAT activities and inversely with apo B levels and the cardiac risk ratio apo B/A-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Adherence to continuous screening for colorectal neoplasia.

Continuous screening is defined as the periodic provision of an opportunity for diagnostic testing to a population of individuals who are asymptomatic and at increased risk for disease. If screening is offered periodically irrespective of response to an earlier screening invitation, this situation may be referred to as serial screening. When continuous screening is made available only to individuals who had tested previously, population member response is referred to as repeat screening. This study assessed adherence to serial- and repeat-colorectal cancer screening among older adult members of an independent practice association-type health maintenance organization (HMO) in two consecutive rounds of screening. In the first screening round, fecal occult blood tests (FOBTs) were sent to 1,565 subjects who were randomly assigned to receive usual care or behavioral interventions intended to encourage testing. Overall, 647 (41%) subjects completed and returned their tests. In the second screening round, FOBTs were mailed again to all subjects; however, the interventions were discontinued. Logistic regression analysis results shows that first-round testing was a significant independent predictor of serial adherence for subjects older than 65 years of age (odds ratio[OR] = 10.8) and those younger than 65 years of age (OR = 10.9); and a significant negative association between exposure to first-round intervention and serial adherence (OR = 0.5) was found among younger subjects. Among first-round adherers, age was significantly and positively related to repeat adherence (OR = 1.6). However, exposure to first-round intervention and having an abnormal FOBT result were significantly and negatively associated with repeat adherence (OR = 0.5 and OR = 0.4, respectively). The results of this study reported here indicate that previous screening is a strong predictor of serial adherence, and special efforts may be required to achieve high levels of serial and repeat adherence among younger adults. Additional research is needed to understand why persons with abnormal screening test results are unlikely to engage in repeat screening.

Age Factors↗
PubMed1993

Screening for colorectal neoplasia: physicians' adherence to complete diagnostic evaluation.

This prospective study was done in a health maintenance organization colorectal cancer screening program to determine whether 166 persons found to have abnormal fecal occult blood test results typically underwent complete diagnostic evaluation (i.e., either colonoscopy or barium enema x-ray plus flexible sigmoidoscopy). Chart audit data show that 137 (82%) subjects contacted a physician to discuss follow-up. A complete diagnostic evaluation was recommended to only 52 (38%) patients who talked with a physician. Forty-two (81%) patients who were advised to get a complete diagnostic evaluation actually complied. Significant differences in clinical findings were observed for patients who did and did not have a complete diagnostic evaluation.

Colorectal Neoplasms↗
PubMed1992

Axial myopia in eyes with optic nerve hypoplasia.

Given that abnormal visual experience during post natal development interferes with emmetropization, we proposed that eyes with hypoplastic optic nerves were predisposed to the development of refractive errors. Six of 14 patients with unilateral optic nerve hypoplasia and 5 of 22 patients with bilateral involvement had at least 4 D of myopia. Nine of the 11 patients with asymmetric bilateral involvement had relative myopia in the eye with the more abnormal optic nerve; none of the patients with symmetric bilateral involvement had a significant interocular refractive difference. Analysis of axial length measurements obtained in 10 of the 11 patients with high myopia showed a significant increase in total axial length. The presumed normal eye of patients with unilateral involvement was significantly smaller than the mean value for age-adjusted normals. We suspect that visual input to the central nervous system is one of the feedback signals involved in the regulation of ocular growth.

Adolescent↗
PubMed1992

Prevalence and mortality rate of congestive heart failure in the United States.

OBJECTIVES: The study was designed to determine the prevalence and mortality rate of congestive heart failure in noninstitutionalized men and women in the U.S. BACKGROUND: Congestive heart failure is a serious condition with significant morbidity and mortality. Earlier epidemiologic descriptions of congestive heart failure were constructed from small surveys, limited data, hospital records or death certificates. No nationally representative data from noninstitutionalized persons have been examined. METHODS: Data collected from the National Health and Nutrition Examination Survey (NHANES-I, 1971 to 1975) were used to determine the prevalence of heart failure on the basis of both self-reporting and a clinical definition. Mortality data were derived from the NHANES-I Epidemiologic Follow-up Study (1982 to 1986). RESULTS: The prevalence of self-reported congestive heart failure approximates 1.1% of the noninstitutionalized U.S. adult population; the prevalence of congestive heart failure based on clinical criteria is 2%. These estimates suggest that between 1 and 2 million adults are affected. Mortality at 10 and 15 years for those persons with congestive heart failure increases in graded fashion with advancing age, with men more likely to die than women. In the group greater than or equal to 55 years old, the 15-year total mortality rate was 39.1% for women and 71.8% for men. CONCLUSIONS: Congestive heart failure is a common problem in the U.S., with significant prevalence and mortality, both of which increase with advancing age. As the population of the U.S. becomes older, the health care impact of congestive heart failure will probably grow.

Adult↗
PubMed1992

Effects of ascorbic acid and pyridoxine supplementation on oxalate metabolism in peritoneal dialysis patients.

We studied the effect of vitamin C and B6 supplementation on oxalate metabolism in seven patients receiving chronic peritoneal dialysis therapy. The study was divided into three phases, each lasting 4 weeks. Plasma oxalate, total ascorbic acid, and pyridoxal-5'-phosphate (PLP) were measured at the end of each phase. Twenty-four-hour urinary excretion and dialysate removal rates of oxalate were also obtained. At the end of phase I (supplement-free period), plasma oxalate levels were markedly elevated at 47.6 +/- 7.1 mumol/L (437 +/- 66 micrograms/dL) (normal, 3.4 +/- 0.4 mumol/L [30.3 +/- 1.6 micrograms/dL]). Plasma total ascorbic acid levels were 62 +/- 6 mumol/L (1.0 +/- 0.1 mg/dL) (normal, 45 to 57 mumol/L [0.8 to 1.0 mg/dL]), while plasma PLP levels were markedly reduced to 24 +/- 5 nmol/L (normal, 40 to 80 nmol/L). Daily supplements of 0.57 mmol (100 mg) ascorbic acid orally (phase II) resulted in a 19% increase in the plasma oxalate levels to 57.8 +/- 6.1 mumol/L (520 +/- 55 micrograms/dL) (P less than 0.03), with a concomitant 60% increase in the plasma ascorbate levels (91 +/- 6 mumol/L [1.6 +/- 0.1 mg/dL], P less than 0.01). Plasma PLP values remained low. Finally, during phase III (0.57 mmol or 100 mg ascorbic acid plus 59.6 mumol or 10 mg pyridoxine HCI orally daily), plasma oxalate levels declined by 17% to 47.9 +/- 5.2 mumol/L (431 +/- 47 micrograms/dL) (P greater than 0.05 v phase II).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Ascorbic acid supplements in patients receiving chronic peritoneal dialysis.

Ascorbic acid supplements are commonly prescribed to patients with end-stage renal disease receiving peritoneal dialysis. To establish the need for ascorbic acid supplements, we evaluated seven chronic peritoneal dialysis patients during a supplement-free (phase I) period, and while receiving oral ascorbic acid (0.57 mmol/d [100 mg/d]) (phase II). Because of a proposed interaction with vitamin B6, patients were additionally supplemented with pyridoxine HCl (59.6 mumol/d [10 mg/d]) (phase III). Plasma levels and dialysate removal rates of total ascorbic acid and plasma pyridoxal-5-phosphate (PLP) were measured at the end of each phase. During phase I, plasma ascorbic acid levels (normal, 45 to 57 mumol/L [0.8 to 1.0 mg/dL]) declined slightly from 74 +/- 11 mumol/L (1.3 +/- 0.2 mg/dL) to 62 +/- 11 mumol/L (1.1 +/- 0.2 mg/dL) (P less than 0.02) at the end of the third week, and then remained stable to the end of the fourth week. Plasma ascorbic acid levels were no different in patients with or without residual renal function. With the addition of vitamin C supplements, plasma ascorbic acid levels increased by 45% of the baseline value at the end of phases II (P less than 0.001). The dialysate removal rate of ascorbic acid was 0.28 +/- 0.03 mmol/d (50 +/- 6 mg/d) at the end of phase I, and increased by 57% of the baseline value at the end of phases II (P less than 0.001). However, the peritoneal clearance of ascorbic acid remained unchanged during all phases the study. Pyridoxine depletion or repletion had no effect on plasma ascorbic acid levels (P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Behavioral interventions to increase adherence in colorectal cancer screening.

This investigation was a randomized controlled trial to determine the impact of health education interventions on the return of mailed fecal occult blood (FOB) tests (FOBT adherence) in a colorectal cancer screening program. The study sample included 2,201 men and women aged 50 to 74 years who were members of an Independent Practice Association (IPA)-type health maintenance organization (HMO). Subjects were randomly assigned to a "usual care" Control Group (advance letter, screening kit, reminder letter), and Treatment Groups 1 (usual care + reminder call), 2 (usual care + self-held screening booklet + reminder call), or 3 (usual care + self-held screening booklet + instruction call + reminder call). Bivariate analysis revealed significant differences in adherence (P less than .001) across study groups: Control Group (27%), Group 1 (37%), Group 2 (37%), Group 3 (48%). In addition, a significant positive association between age and adherence (P less than .001) was found. Logistic regression analysis revealed an interaction between sex and treatment. Adherence among men in all treatment groups increased significantly (P less than .0001) in relation to Control Group males. Men in Group 3 also were more likely to adhere than those in Group 2 (P less than .01) or Group 1 (P less than .01). Among women, adherence was significantly higher in Group 3 than in Group 2 (P less than .03), Group 1 (P less than .025), or the Control Group (P = .0008). The primary reason cited for nonadherence was perceived inconvenience of the FOB testing procedure.

Aged↗