Search PubMed⌕ Search

Biomedical subjects

M M Harris

Publications and source records attributed to M M Harris.

30 records · Page 2Linked to original sources
PubMed1985

Mutagenicity of drinking water detected by the Tradescantia micronucleus test.

Spring Lake reservoir of Macomb, Illinois, is a typical model of the drinking water supply of some midwestern towns of the United States. Water samples collected periodically in 1980 and 1981 from this lake were tested for mutagenicity using the Tradescantia micronucleus (Trad-MCN) test, a highly sensitive mutagen-detecting bioassay. Water samples from 1981 were also analyzed chemically. The micronucleus (MCN) frequency peaked (12-14 MCN/100 tetrads) in mid-July in both years, as compared with the average frequency (5 MCN/100 tetrads) of the base-line control that was maintained in nutrient solution (prepared with distilled water and pure chemicals). Drinking water from the tap was tested in parallel with lake water, and its mutagenicity tended to fluctuate with the mutagenicity of the lake water.

Cell Nucleus↗
PubMed1985

Platelet activation and secretion associated with emotional stress.

Platelets are believed to play a role in the pathogenesis of atherosclerosis and of the vascular obstruction that causes the acute complications of coronary artery disease. Since specific behavioral patterns appear to be related to the development of coronary artery disease and since emotional stress may predispose an individual to acute cardiovascular ischemia, it was hypothesized that platelet activation by catecholamines might be involved in these events. To study emotional stress, plasma samples were obtained from 61 senior medical residents immediately before they were to speak in public. There were significant increases in the plasma concentrations of the platelet-secreted proteins platelet factor 4 and beta-thromboglobulin and epinephrine and norepinephrine immediately before speaking, which demonstrates that platelet activation and secretion occur in association with this type of emotional stress. Four trials were carried out to study the mechanism for this observed platelet secretion: (1) phenoxybenzamine, (2) propranolol, (3) 650 mg aspirin, and (4) 80 mg aspirin were given several hours before the public speaking engagement. Neither phenoxybenzamine nor propranolol in doses that blocked the hemodynamic effects of alpha 1- and beta 1-adrenergic stimulation modified platelet secretion. Aspirin also did not block platelet secretion, which suggests that platelets were not being stimulated through a cyclooxygenase-dependent pathway. This study provides direct evidence of platelet secretion in vivo in association with emotional stress, and underscores the potential importance of platelet activation and secretion in the acute events that occur in patients with vascular disease.

Adult↗
PubMed1983

Tradescantia-Micronucleus (Trad-MCN) test on the genotoxicity of malathion.

The Tradescantia-Micronucleus (Trad-MCN) bioassay was utilized to determine the genotoxicity of Malathion, a common insecticide. Four different treatment procedures were applied: a) absorption of Malathion/water mixture (with or without DMSO and/or S-9) through the stem, b) spraying a Malathion/water mixture onto the plant cuttings in enclosed chambers, c) spraying a Malathion/water mixture on an open population of plants in the greenhouse, and d) absorption of Malathion fumes through the leaves and buds. Most treatments were administered for 6 hr, followed by a 24-hr recovery time. Slides were prepared from the samples and scored for micronucleus (MCN) frequencies. Results of 16 experiments indicated that the genotoxicity of liquid Malathion absorbed through the stem was very low and often masked by high toxicity, causing dead cells in the stem, leaves, and meiocytes. Malathion spray at the dosage of 0.435% in an enclosed chamber or on an open population of plants yielded negative responses. Malathion fumes at dosages of 0.15-0.25% induced significantly higher (0.05) MCN frequencies above the controls and altered the nuclear structure to form unequal sized nuclei and multiple breaks in each of the four cells of a tetrads. It also caused degeneration of nuclei, "protrusions on nuclei," and inhibition of cell growth. Higher dosages (above 0.25%) were toxic.

Animals↗
PubMed1980

A non-surgical method of reducing drooling in cerebral-palsied children.

A programme is described which aimed to reduce drooling volume in groups of cerebral-palsied children. The programme, which lasted one year, required the children to wear chin cups and to attend special 'anti-drooling' classes. The over-all reduction in volume of drooling was 73 per cent.

Adolescent↗
PubMedDate not supplied

Tradescantia-Micronucleus (Trad-MCN) tests on 140 health-related agents.

The Tradescantia-Micronucleus (Trad-MCN) test is a simple short-term bioassay for various gaseous and liquid forms of chemical agents, and physical agents such as radiation. 140 agents, directly or indirectly related to human health, were screened for their mutagenicity. Plant cuttings of young inflorescences, in which the pollen mother cells undergo various stages of meiosis, were maintained in nutrient solution for experimentation. Treatments were made either by absorption of the soluble agents through the stem, by diffusion of gaseous agents through the leaves and buds, by exposure to internal/external radiation or by in situ exposure to air pollutants. Micronuclei formed from damaged chromosomes served as the indicators of mutagenicity. Results of 140 agents tested are listed in 9 different categories. (1) Carcinogens/mutagens, (2) common beverages, (3) common chemicals, (4) drugs, (5) pesticides, (6) common household chemicals, (7) radiation and radioisotopes, (8) in situ monitoring, (9) complex environmental mixtures. Out of 140 agents tested, 52 showed positive, 20 showed borderline positive responses and 5 showed strong toxicity. Test results of 41 agents in the present study showed 67% congruity with Ames test results found in the literature.

Beverages↗
PubMedDate not supplied

Treatment of shivering after epidural lidocaine.

The effectiveness of intravenous meperidine and warm local anesthetic for prevention of postanesthetic shivering was evaluated in urology patients undergoing epidural blockade for extracorporeal shockwave lithotripsy. When administered before the blockade, meperidine, 12.5 mg or 25 mg, was not significantly better than saline placebo for preventing postepidural shivering. Changes in the concentrations of catecholamines or lidocaine did not result in differences between patients who shivered and those who did not shiver. In a second experiment, patients receiving body-temperature or room-temperature epidural lidocaine did not differ with respect to the incidence of postanesthetic shivering, onset of sensory blockade, or core temperature during a 30-minute observation period. The authors concluded that neither meperidine, in doses employed, nor body-temperature lidocaine prevents shivering after epidural blockade. This shivering appears to be different from that observed during emergence from general anesthesia.

Anesthesia, Epidural↗