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Biomedical subjects

H Taylor

Publications and source records attributed to H Taylor.

At least 199 records · Page 11Linked to original sources
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Plant antimutagenic agents, 2. Flavonoids.

A number of known prenylated flavonoids were isolated from Psoralea corylifolia using an assay procedure based on inhibition of the mutagenic action of 2-aminoanthracene on Salmonella typhimurium (T-98). All of these compounds were toxic rather than antimutagenic or desmutagenic. Bakuchiol [17], a known prenylated phenolic terpene, was also isolated; its activity was not due to toxicity. Biochanin A [4], a known isoflavone, was similarly isolated from Cicer arientinum and was active and nontoxic. Some of the above flavonoids were studied for inhibition of the mutagenicity of several different mutagens with results depending upon the structure of the flavonoid and the mutagen.

Anthracenes↗
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Plant antimutagenic agents, 3. Coumarins.

Several coumarins were isolated from crude plant extracts by means of an antimutagenic assay procedure. These coumarins included psoralen from Psoralea corylifolia and imperatorin and osthol from Selinum monniere. Studies of structure-activity relationships of these and several other available coumarins were carried out with four mutagens. All of the coumarins were nontoxic and in particular showed high activity in the inhibition of the mutagenicity of benzo[a]pyrene.

Benzo(a)pyrene↗
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Plant antimutagenic agents, 4. Isolation and structure elucidation of maesol, an inactive constituent of Maesa spp.

Maesol, a novel dimeric phenol, was isolated from seeds of Maesa montana and Maesa indica. Maesol was shown to have the formula C28H42O4 with structure 1, a dimeric, symmetrical 1,12-bis(3,3'-dihydroxy-4,4'-dimethyl-5,5'-dimethoxyphenyl)dodecane. It is the first compound with such structure to be isolated from plant material. Structure elucidation was based largely on 1H- and 13C-nmr techniques and comparison with a known synthetic isomeric dimer 3. Although crude extracts showed strong inhibition of 2-aminoanthracene activity against Salmonella typhimurium (T-98), the pure compound was inactive when tested for inhibition of the mutagenic activity of several mutagens.

2-Acetylaminofluorene↗
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Plant antimutagenic agents, 5. Isolation and structure of two new isoflavones, fremontin and fremontone from Psorothamnus fremontii.

Two new isoflavones, fremontin and fremontone, were isolated from roots of Psorothamnus fremontii (Fabaceae), a desert plant. Compound 1 has the structure 5'-(alpha, alpha-dimethylallyl)-5,7,2',4'-tetrahydroxyisoflavone; compound 2 is similar but also contains the 3'-(gamma,gamma-dimethylallyl) substituent. The alpha,alpha-dimethylallyl substituent is rarely observed, and the combination of the alpha,alpha- and gamma,gamma-dimethylallyl substituents is unprecedented. Both 1 and 2 were nontoxic toward Salmonella typhimurium and were both highly active in the inhibition of mutagenicity of ethyl methanesulfonate (EMS) at all concentrations tested. Compound 2 was more active than 1 in the inhibition of mutagenicity of 2-aminoanthracene (2AN) and acetylaminofluorene (AAF) toward S. typhimurium.

Animals↗
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Plant antimutagens, 6. Intricatin and intricatinol, new antimutagenic homoisoflavonoids from Hoffmanosseggia intricata.

Intricatin [1] and intricatinol [2] are new homoisoflavonoids isolated from a desert plant Hoffmanosseggia intricata, which was collected in Baja California, Mexico. The structures of the compounds were elucidated using a variety of spectroscopic techniques. The structure of 1 was shown to be 7,4'-dimethoxy-8-hydroxyhomoisoflavone, and 2 was shown to be 4'-methoxy-7,8-dihydroxyhomoisoflavone. Both compounds 1 and 2 displayed activity in the inhibition of the mutagenicity of 2AN toward Salmonella typhimurium (T98). Compound 2 was much more active than 1 in the case of the inhibition of the mutagenicity of AAF toward S. typhimurium (T98) and the inhibition of EMS towards S. typhimurium (T100). Compounds 1 and 2 are the first examples of antimutagenic activity in homoisoflavones.

Animals↗
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Plant antimutagenic agents, 7. Structure and antimutagenic properties of cymobarbatol and 4-isocymobarbatol, new cymopols from green alga (Cymopolia barbata).

Two new compounds, cymobarbatol and 4-isocymobarbatol, were isolated from the marine alga Cymopolia barbata. The complete structures and absolute stereochemistries of these compounds were elucidated by a variety of spectroscopic techniques and X-ray crystallography. Both compounds were found to be nontoxic over a broad concentration range to Salmonella typhimurium strains T-98 and T-100. Both compounds exhibited strong inhibition of the mutagenicity of 2-aminoanthracene and ethyl methanesulfonate toward, respectively, the T-98 strain plus a metabolic activator and T-100.

Benzopyrans↗
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Surface engineering of artificial heart valve disks using nanostructured thin films deposited by chemical vapour deposition and sol-gel methods.

Pyrolytic carbon (PyC) is widely used in manufacturing commercial artificial heart valve disks (HVD). Although PyC is commonly used in HVD, it is not the best material for this application since its blood compatibility is not ideal for prolonged clinical use. As a result thrombosis often occurs and the patients are required to take anti-coagulation drugs on a regular basis in order to minimize the formation of thrombosis. However, anti-coagulation therapy gives rise to some detrimental side effects in patients. Therefore, it is extremely urgent that newer and more technically advanced materials with better surface and bulk properties are developed. In this paper, we report the mechanical properties of PyC-HVD, i.e. strength, wear resistance and coefficient of friction. The strength of the material was assessed using Brinell indentation tests. Furthermore, wear resistance and coefficient of friction values were obtained from pin-on-disk testing. The micro-structural properties of PyC were characterized using XRD, Raman spectroscopy and SEM analysis. Also in this paper we report the preparation of freestanding nanocrystalline diamond films (FSND) using the time-modulated chemical vapour deposition (TMCVD) process. Furthermore, the sol-gel technique was used to uniformly coat PyC-HVD with dense, nanocrystalline-titanium oxide (nc-TiO2) coatings. The as-grown nc-TiO2 coatings were characterized for microstructure using SEM and XRD analysis.

Biomedical Engineering↗
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The Psychophysiological Investigations of Myocardial Ischemia (PIMI) study: objective, methods, and variability of measures.

OBJECTIVE: This study evaluated physiological, neuroendocrine, and psychological status and functioning of patients with coronary artery disease in order to clarify their role in the expression of symptoms during myocardial ischemia (MI), and to establish repeatability of responses to mental stress. Design and methods of the study are presented. METHODS: One hundred ninety-six coronary artery disease patients were examined during physical and mental stress tests in four hospitals. Eligibility criteria included narrowing of at least 50% in the diameter of at least one major coronary artery or verified history of myocardial infarction, and evidence of ischemia on an exercise treadmill test. Psychological, biochemical, and autonomic function data were obtained before, during, and after exposure to mental and exercise stressors during 2 or 3 half-days of testing. Ventricular function was assessed by radionuclide ventriculography, and daily ischemia by ambulatory electrocardiography. Sixty patients returned for a short-term mental stress repeatability study. Twenty-nine individuals presumed to be free of coronary disease were also examined to establish reference values for cardiac responses to mental stress. RESULTS: Study participants were 41 to 80 years of age; 83 (42%) had a history of MI, 6 (3%) of congestive heart failure, and 163 (83%) of chest pain; 170 (87%) were men; and 90 (46%) had ischemia accompanied by angina during exercise treadmill testing. Ischemia during ambulatory monitoring was found in 35 of 90 (39%) patients with and 48 of 106 (45%) patients without angina during exercise-provoked ischemia. Intraobserver variability of ejection fraction changes during bicycle exercise and two mental stress tests (Speech and Stroop) was good (kappa = 1.0, .90, and .76, respectively; percent agreement = 100, 97.5, and 93.8%, respectively). Variability of assessed wall motion abnormalities during bicycle exercise was better (kappa, agreement = 85%) than during Speech or Stroop kappa and .57, percent agreement = 70% and 82.5%, respectively). CONCLUSIONS: Study design, quality control data, and baseline characteristics of patients enrolled for a clinical study of symptomatic and asymptomatic myocardial ischemia are described. Lower repeatability of reading wall motion abnormalities during mental stress than during exercise may be due to smaller effects on wall motion and lack of an indicator for peak mental stress.

Adult↗
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The new medical marketplace: physicians' views.

The transformation of the medical marketplace has major implications for the physician workforce. Findings are reported here from national surveys of physicians, hospitals, health maintenance organizations (HMOs), preferred provider organizations (PPOs), and medical group practices conducted in 1995 to measure the impact of those changes. Physicians in higher HMO penetration states were more likely to report serious problems with several aspects of medical practice and patient care and were more likely to perceived oversupply in their specialty areas and changes in their practice arrangements. Some divergence is noted in views of supply between physicians and those that employ them. The majority of physicians would still recommend medicine and their specialty as a career.

Attitude of Health Personnel↗
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Volume reduction of arm lymphoedema.

Most of the volume reduction in an 11-day course of compression bandaging for severe cancer-related arm lymphoedema appeared to occur in the first few days. This study therefore compared the volume loss during days 1-4 with 5-11. Fifteen consecutive courses of bandaging were studied. Arm volume was estimated on days 1, 5 and 11. The volume reduction during days 1-4 was compared with days 5-11 using the Wilcoxan Ranked Pairs Test. Seventy nine per cent of the total median volume reduction occurred during days 1-4. The difference between the two periods was highly significant (p < 0.001). The duration of compression bandaging has therefore been reduced to 4 days for severe cancer-related arm lymphoedema in this clinic.

Bandages↗
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Physicians' responses to their changing environment.

The loss of physician autonomy, the changing shape of physicians' practices, and efforts to control the cost of health care have left American physicians increasingly dissatisfied with the U.S. health care system. A survey of 300 office and hospital-based physicians shows 59 percent favor reform of the U.S. system; only 31 percent favor retaining the current system. Doctors face increased competition for patients (the supply of physicians has increased three times faster than the population), reduced autonomy because of intervention by government and other third party payers, pressure from patients to provide unnecessary care including expensive new technology, and increased cost containment. Yet a majority of physicians believe the causes of rising health care costs are patient demand for services and the current medical malpractice system. A minority (23 percent) blame hospitals and physicians for rising costs.

Attitude of Health Personnel↗
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Rochester, New York: a model for health reform.

The 50-year-old health care experiment conducted in Rochester, New York, has yielded encouraging results. The policies implemented there include coverage by a single payer, community rating, a spending cap, encouraged use of HMOs, and general cooperation among providers, employers, insurers, and the area's one million residents. Surveys of those residents and local employers indicate that they are more satisfied with Rochester's health system than the rest of Americans are with the U.S. system.

Attitude to Health↗
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Plantar approach for excision of bilateral soft tissue masses in a child.

A painful soft tissue mass of the plantar aspect of both feet, in a 5-year-old child, is presented. Plantar incisions are ideal in specific cases as long as the surgeon adheres to certain principles, as outlined in this manuscript. A discussion of lipomas is also presented. Optimum exposure is the key to total eradication of soft tissue lesions and to proper maintenance of wound healing. Location of the lesion presented warranted use of the plantar approach. Minimal hypertrophy of the plantar scar was achieved, as well as few symptoms by the patient.

Child, Preschool↗
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Isolated unilateral gaze palsy.

A case of an isolated unilateral horizontal gaze paralysis is presented. The abnormality has remained static and in isolation for more than three years. A review of the benign causes of pontine gaze palsies is presented. The unique features of this case is the fact that the gaze paralysis is unilateral and unassociated with any other neurologic or systemic abnormality.

Child, Preschool↗