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Biomedical subjects

W A Anderson

Publications and source records attributed to W A Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1994

Antimicrobial activity of bark extracts of Bridelia ferruginea (Euphorbiaceae).

Water and ethanol extracts of Bridelia ferruginea were examined for phytochemical and antimicrobial properties. The extracts, which were tested at a final concentration of 5 mg/ml, produced in vitro antimicrobial activities in assays against hospital strains of Staphylococcus aureus, Candida albicans, Staphylococcus epidermidis, Escherichia coli, Streptococcus lactis, Proteus vulgaris, Proteus mirabilis, Streptococcus pyogenes and Klebsiella sp. The zones of inhibition produced by the extracts in agar diffusion assays against the test micro-organisms ranged from 4 to 20 mm, while the chloramphenicol antibiotic control produced zones that measured 15-36 mm. Preliminary phytochemical analysis of the plant extracts showed the presence of phenols and tannins. Sesquiterpenes, anthroquinones, and saponins were not detected in the extracts. The Gram-negative bacteria appeared to be more susceptible (4-20 mm) to the antimicrobial effect of the extracts than the Gram-positive organisms (4-18 mm).

Anti-Bacterial Agents↗
PubMed1994

Coronary artery bypass grafting after pneumonectomy.

Coronary artery bypass grafting was carried out in a 61-year-old man 42 years after he had undergone right pneumonectomy. At the time of operation, the heart was displaced into the right hemithorax, which required modification of the operative techniques. Despite poor pulmonary function tests results preoperatively, the patient had an uneventful postoperative course. The success in this patient may be attributed to careful preoperative preparation, flexibility in the choice of techniques for establishment of cardiopulmonary bypass and coronary artery bypass grafting, and careful attention to perioperative fluid management.

Coronary Artery Bypass↗
PubMed1994

Application of a log-logistic model to describe the survival of Yersinia enterocolitica at sub-optimal pH and temperature.

A log-logistic model previously used to describe the thermal inactivation of microorganisms has been applied to predict accurately the survival of Yersinia enterocolitica under conditions of sub-optimal temperatures (0-23 degrees C) and growth inhibitory pH values for a number of different acidulants. Predictions from the model were also compared to observed survival times of Y. enterocolitica in mayonnaise and were found to be in excellent agreement. However in yoghurt the model overestimated survival of this organism at both 20 and 4 degrees C but would 'fail safe' if used for predictive purposes. The discrepancy in yoghurt is discussed.

Food Microbiology↗
PubMed1994

The impact of aprotinin on coronary artery bypass graft patency.

STUDY DESIGN: Aprotinin has recently been shown to reduce postoperative bleeding and transfusion requirements associated with coronary artery bypass grafting. One concern with its use, however, is that it may have a deleterious effect on graft patency because it promotes hemostasis. Forty-seven patients undergoing coronary artery bypass. Forty-seven patients undergoing coronary artery bypass grafting were enrolled in a prospective, randomized double-blind trial of aprotinin to determine the effect of this agent on postoperative bleeding, transfusion requirements, renal function, and graft patency. The study group was comprised of the 32 patients who underwent technically adequate ultrafast CT scans 6 to 8 weeks postoperatively to determine graft patency. Sixteen patients received aprotinin (aprotinin group) and 16 received placebo (control group). RESULTS: Demographic and operative descriptors were comparable between groups. Postoperative mediastinal and chest tube drainage in the aprotinin group was significantly less than that in the control group (722 vs 1,540 mL; p = 0.0006) and the mean blood transfusion requirements were less, but this did not reach significance (125 vs 297 mL; p = 0.42). Analysis of graft patency by patients revealed that 5 patients in the aprotinin group (31%) had at least one occluded graft, while none of the patients in the control group had an occluded graft (p = 0.04). Analysis by graft revealed that 38 of 43 grafts placed in the aprotinin group were patent, while all 38 grafts placed in the placebo group were patent (88.4 vs 100%; p = 0.057). There was no difference in the incidence of myocardial infarction, renal dysfunction or hematologic indexes at discharge between the groups, or evidence of other thrombotic complications. CONCLUSION: We conclude that high-dose aprotinin is effective in reducing hemorrhage after coronary artery bypass grafting. However, its routine use should be approached cautiously due to its possible adverse effects on graft patency.

Aged↗
PubMed1994

Acute beneficial effect of Fluosol-DA on urinary excretion of stroma-free hemoglobin in the isolated rat kidney.

In a timed study over 75 min, divided into 5 15-min periods, experimental perfusions of isolated rat kidneys using Krebs-Ringer bicarbonate (KRB) containing 3.5% (uncrosslinked) stroma-free hemoglobin (SFH) plus 3.5% of the perfluorochemical Fluosol-DA were found to excrete only 13% as much total hemoglobin (Hb) as control perfusions using KRB containing 7% SFH alone (controls). The glomerular filtration rate was the same for experimentals and controls in 3 periods, and slightly higher in the experimentals in 2 periods. However, urine flow was found to be significantly decreased in all 5 periods for the experimentals relative to the controls. These effects can be explained by reabsorption of glomerular filtrate containing Hb by endocytosis of renal tubular cells.

Animals↗
PubMed1994

Protooncogene, growth factor, growth factor receptor, and estrogen and progesterone receptor gene expression in the immature rat uterus after treatment with estrogen and tamoxifen.

The mechanism(s) by which estrogen regulates cell growth in target cells and the cascade of biochemical changes associated with growth have not yet been fully determined. Equally undetermined is an understanding of the mechanism(s) by which tamoxifen blocks estrogen-regulated growth. This study, therefore, attempts to define and correlate the physiological processes in the rat uterus following estrogen and tamoxifen administration with temporal events manifested by mRNA expression of protooncogenes (m-myc, c-ras, c-fos, c-jun), growth factors and/or inhibins (IGF-1, IGF-2, IGF-2 Exon 1 and Exon 2), EGF, TGFB-1, -2, -3), growth factor or inhibin receptors (EGFr, TGFB-2r, TGFB-3r), and estrogen-induced differentiative proteins including estrogen receptor (ER), progesterone receptor (PR). In this study, mRNA was isolated from hormone and antagonist-treated rat uteri at 0', 15', 30', 1 h, 6 h, 24 h, 48 h and 72 h. Expression studies were analysed by dot/Northern blot hybridization with cDNA or oligonucleotide probes for the RNAs mentioned above. Nuclear runoff transcriptional assays were also performed. Our data suggest that fos, myc, ras and jun protooncogenes were expressed from 15' to 48 h after treatment with either estrogen or tamoxifen. Tamoxifen treatment resulted in diminished expression, but incomplete inhibition of the protooncogene mRNAs. Estrogen treatment resulted in rapid elevation of both EGF and EGFr mRNA levels, both of which were suppressed after tamoxifen treatment. Tamoxifen may exert its antiestrogenic effects by inhibiting EGF and EGFr, and myc protooncogene activity on the one hand, and by overexpression of the TGFB isotypes and their receptors on the other hand. With the proliferation cycle short circuited, tamoxifen-treated cells hypertrophied and differentiated to terminal cells by 24-48 h. Working hypotheses for the mechanisms of action of estrogen and tamoxifen are presented based on our data.

Animals↗
PubMed1994

Estrogen induced peroxidase secretion from the endometrial epithelium: a possible function for the luminal enzyme.

Estrogen induced peroxidase (EIP) activity revealed as a diaminobenzidine-H2O2 product in electron micrographs is apparent within cisternae of the RER and in large dilated apical vesicles, of which only a few have been seen to open into the uterine lumen. EIP activity is infrequently present in the trans cisternae of the rather diminutive Golgi complex in uterine epithelial cells from 12-72 h after treatment with estrogen. EIP activity is, however, prominent on the surface of microvilli of epithelial cells and as deposits in the lumen. Desalted uterine fluid (72 h) isolated by rotofor (Biorad) and analysed on isoelectric focusing gels that were stained with the diaminobenzidine-H2O2 reaction, reveal the existence of at least 6 peroxidase isoelectric variants with isoelectric points between pI 3.5 and pI 5.0. In similar preparations doubly-stained by diaminobenzidine-H2O2 and silver, peroxidase positive bands are enhanced, along with other isoelectric variants in the acidic pI range. In SDS-PAGE preparations, five prominent proteins ranging from 29-115 kD are present in 72 h uterine fluid. Luminal EIP coats the surface microvilli of the reproductive tract cells, and of viable spermatozoa incubated in uterine fluid. Peroxidase coated bacteria appear to be in the process of decay, and enzyme activity is present on the surface of most spermatozoa. It is not yet determined if EIP has bactericidal, spermicidal or capacitation functions.

Animals↗
PubMed1994

Early and late-phase events after valve replacement with the St. Jude Medical prosthesis in 1200 patients.

From May 1982 to August 1991, 1200 patients underwent valve replacement with the St. Jude Medical (St. Jude Medical, Inc., St. Paul, Minn.) valve: 615 men (51%) and 585 women, mean age 58 years. Preoperatively, 830 patients (69%) were in functional class III or IV. A total of 611 patients (51%) had the aortic valve replaced, 490 (41%) the mitral valve, 2 (0.2%) the tricuspid valve, and 97 (8%) multiple valves. There were 81 hospital deaths (6.8%). Risk factors included older age (p = 0.0001), female gender (p = 0.02), higher preoperative left ventricular end-diastolic pressure (p = 0.05), previous cardiac operation (p = 0.003), longer aortic crossclamp time (p = 0.0001), and longer cardiopulmonary bypass time (p = 0.0001). Follow-up was 98% complete (3153 patient-years). There were 152 late deaths; 32 (21%) were considered valve-related: six thromboembolism, four valve thrombosis, five anticoagulant-related hemorrhage, eight prosthetic valve endocarditis, one paravalvular leak, and seven sudden death. The 5-year actuarial survival was 75%. Risk factors for late death included older age (p = 0.03), lower preoperative ejection fraction (p = 0.005), longer aortic crossclamp time (p = 0.001), longer cardiopulmonary bypass time (p = 0.0001), previous cardiac operation (p = 0.02), and higher preoperative functional class (p = 0.0001). Actuarial freedom at 5 years from major thromboembolic events and anticoagulant-related hemorrhage was 97% and 95%, respectively. This value for valve thrombosis was 99%, for reoperation 96%, for prosthetic valve endocarditis 98%, and for paravalvular leak 96%. Actuarial freedom from all valve-related events and valve-related death at 5 years was 74% and 94%, respectively. We conclude that the low incidence of valve-related events and low mortality supports the continued use of the St. Jude Medical valve.

Actuarial Analysis↗
PubMed1993

Chronic type A aortic dissection: an unusual complication of cocaine inhalation.

Acute aortic pathology temporally related to cocaine inhalation may lead to frank rupture or acute aortic dissection. This is a report of an unusual case of a 43-year-old man who presented 9 weeks after experiencing a tearing sensation in his chest while smoking cocaine. The diagnosis was chronic type A aortic dissection with 4+ aortic insufficiency. The successful surgical management included resuspension of the aortic valve and placement of a Dacron tube graft in the ascending aorta such that flow was maintained distally in both the true and false lumens.

Administration, Inhalation↗
PubMed1993

Management of an innominate artery aneurysm during an open heart operation.

A 76-year-old woman was found to have a 4 x 2.5-cm saccular aneurysm at the origin of the innominate artery at the time of a reoperative open heart operation. The operative procedure was modified to include repair of the aneurysm with a Dacron patch. During the period of innominate artery occlusion, the patient was cooled to 25 degrees C and the mean arterial pressure was maintained at 90 mm Hg to maximize cerebral protection.

Aged↗
PubMed1993

Valve-related events and valve-related mortality in 340 mitral valve repairs. A late phase follow-up study.

To assess the early and late valve-related events, 340 consecutive patients undergoing mitral valve repair from 1969 to 1988 were evaluated. Follow-up was complete, with a mean of 7.5% years and range from 2 to 22 years (cumulative 2456 patient-years). There were 221 (65%) female patients. Rheumatic valvular disease was present in 246 (68%) patients. The remaining patients had ischemic or congenital valve disease, floppy valve or infective endocarditis. At surgery, 47% of the patients had pure mitral incompetence, 43% had mixed mitral stenosis and incompetence and 10% had predominant mitral stenosis. Seventy-three percent of the patients were in functional class III or IV. Twelve percent had had prior heart surgery. Concomitant valve procedures including coronary revascularization were performed in 62.3%. There were 23 hospital deaths (6.8%) but only 3 of these (0.8%) were valve-related in patients who died at reoperation for valve repair failure. There were 4 other early repair failures who survived early reoperation. Of the 317 hospital survivors, there were 127 late deaths, and an actuarial survival of 44 +/- 3.7% (70% CL) at 14 years. Of these, 13 were valve-related or 0.5% patient-year. Late events included thromboembolism (TE) 1% patient-year, anticoagulant bleeding 0.4% patient-year, infective endocarditis (IE) 0.2% patient-year and late reoperation for mitral valve repair failure in 63 patients or 2.8% patient-year. At the late follow-up, 88% of the hospital survivors were in functional class I or II.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1992

Factors affecting mitral valve reoperation in 317 survivors after mitral valve reconstruction.

From a very heterogeneous group of 340 patients undergoing mitral valve reconstruction from 1969 through 1988, 313 hospital survivors were analyzed for factors affecting the occurrence of reoperative mitral valve procedures related to native mitral valve dysfunction. Follow-up was 100% and extended from 1 year to 20 years (mean follow-up, 7.2 years). Sixty-three patients (18.5% of the 340) required mitral valve reoperation at a mean postoperative interval of 6 years (range, 1 to 15 years). Incremental risk factors analyzed for the event late mitral valve failure included age, sex, preoperative New York Heart Association class, cause of valvular disease, pathophysiology of the mitral valve, previous mitral valve operation, mitral valve pathology, and estimation of mitral valve function at operation after repair. Mitral valve pathophysiology affected the actuarial freedom from mitral valve replacement (p = 0.023 [log-rank]). Actuarial freedom from mitral valve reoperation was 90% at 5 years and 80% at 8 years in patients who had either pure mitral regurgitation or isolated mitral stenosis compared with 80% and 72% at 5 and 10 years, respectively, in patients who had mixed mitral stenosis and regurgitation (p = 0.023). Patients undergoing late reoperation were younger (51.7 +/- 1.56 years [+/- the standard error of the mean]) than those not having reoperation (p less than 0.0003). Durability of the repair was less in patients with rheumatic heart disease (p less than 0.025) and greater in patients with ischemic heart disease (p less than 0.004). Seventy-three percent of patients undergoing reoperation had concomitant operations compared with 68% of those not having reoperation (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Cryopreserved allograft veins as alternative coronary artery bypass conduits: early phase results.

Traditional autologous conduits are sometimes unavailable or unsuitable to permit total revascularization during coronary artery bypass grafting. In these patients the results of using nonautologous alternative conduits has been disappointing. Encouraged by the excellent long-term results seen with cryopreserved allograft valves, a clinical protocol was developed to evaluate the use of a commercially cryopreserved allograft saphenous vein (CPV). Our protocol consisted of using CPV when left internal mammary arteries and autologous saphenous vein grafts were unavailable or unsuitable for complete revascularization. Blood group (ABO) typed CPVs were thawed and implanted as required using standard surgical techniques. From December 1989 through June 1991, 19 of 1,602 patients who underwent coronary revascularization had CPVs implanted (1.2%). There were no operative deaths. An attempt was made to evaluate the patency of all grafts with coronary arteriography or ultrafast computed tomographic scans. Fourteen patients were available for patency evaluation. Patency rate in the 14 patients studied at a mean of 7 +/- 2 months (range, 2 to 16 months) were: internal mammary artery, 93% (14/15); saphenous vein graft, 80% (4/5); and CPV, 41% (7/17). The patency of the CPV was significantly less than the patency rate for the saphenous vein and internal mammary artery (p = 0.004). We conclude that the short-term patency rate of CPVs is inferior to that of autologous vessels. Due to its poor patency, we recommend that CPV should only be used when no other autologous conduit is available.

Aged↗
PubMed1992

Amelioration of nephrotoxicity associated with synthetic oxygen transport media.

Use of synthetic oxygen transport media offers the potential advantages of reducing requirements for coadministration of blood products and oxygen at the scene of mass casualty situations. Previous studies have shown perfusions of isolated kidneys with stroma-free hemoglobin (SFH) to be physiological while those with Fluosol-DA (20% FDA) have been associated with low glomerular filtration rate, urinary flow rate, and fractional reabsorption of sodium and potassium (FrNa+ and FrK+). In the present studies, perfusions with SFH/FDA mixtures showed normal glomerular filtration rate, a 50% lower urinary flow rate, and FrNa+ values 3% to 5% higher than SFH controls. Compared with 20% FDA perfusions, nephrotoxic effects of SFH/FDA combinations were moderate. Compared with SFH/FDA mixtures, perfusion with 20% FDA showed lower urinary flow and glomerular filtration rates. Ultrastructural assessment of glomerular filter revealed that FDA emulsion particles were adherent to epithelial podocytes. We conclude that resuscitation with a mixture of SFH and FDA may ameliorate the previously reported nephrotoxicity associated with the use of FDA alone.

Animals↗
PubMed1992

NCAA institutionally based drug testing: do our athletes know the rules of this game?

One aspect of the current drug-testing controversy that has gone relatively unexamined concerns the extent to which student-athletes are fully informed of the testing procedures employed by their institution. College athletes (N = 2,282) participating at 11 NCAA-affiliated institutions nationwide were surveyed as to their awareness of their school's drug-testing program. Results indicate athletes have numerous misconceptions regarding the drug testing to which they may be subjected. Over one-third of the athletes attending "testing" institutions were oblivious to the fact their school was engaged in drug-testing, and more than 70% were unable to correctly identify their school's drug-testing protocol. Implications of such ignorance are discussed.

Adult↗
PubMed1991

Modulation of sympathetic activity by brain neuropeptide Y in cardiac hypertrophy.

Several observations now support the view that the sympathetic system actively participates in the development of cardiac hypertrophy. Since norepinephrine (NE)-containing neurons involved in cardiovascular regulation in the brain are known to coexist with neuropeptide Y (NPY), it is possible that a functional interaction between NPY and NE exists centrally. In an effort to clarify whether or not central catecholamine systems are modulated by NPY soon after imposing an increased pressure overload on the heart, male Sprague-Dawley rats underwent aortic constriction and were examined 14 days later. Rats were anesthetized and subjected to microdialysis sampling by stereotaxically implanting a probe into the caudal ventrolateral medulla (A1). Perfusate was collected after a 1-hour stabilization period, purified, and analyzed for interstitial concentrations of NE and other catecholamines using high-performance liquid chromatography with an electrochemical detector. Extracellular NE concentrations in the A1 area were found to be decreased. These results were associated with increased rate of change in the specific activity of NE (NE turnover) in heart, indicating increased sympathetic activity and an increased left ventricular weight. Also, infusion of NPY (10(-9) mol/L) by microdialysis in the A1 area resulted in the reduction of NE concentration; epinephrine and dopamine levels were also decreased. In contrast, methionine-enkephalin, another neuropeptide, had no effect on the extracellular catecholamine concentrations in the A1 area. Since neurons of the A1 group project almost exclusively to forebrain structures inhibiting sympathetic activity, it is concluded that decreases of NE and other catecholamines in afferent pathways regulating the caudal ventrolateral medulla may lead to an enhanced sympathetic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗