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Biomedical subjects

J Meadows

Publications and source records attributed to J Meadows.

47 records · Page 3Linked to original sources
PubMed1986

Uric acid protects membranes and linolenic acid from ozone-induced oxidation.

Aqueous preparations of linolenic acid, bovine serum albumin, and bovine erythrocyte membrane fragments were bubbled with ozone in the presence or absence of uric acid. Ozonation of the membrane fragments or the bovine serum albumin did not result in protein degradation. After 15 min of ozonation, the absorbance of the thiobarbituric acid-reactive material increased by 0.34 in the linolenic acid preparation and by 0.08 in the suspension of membrane fragments. In the presence of uric acid, these changes in absorbance were reduced to 0.14 for the fatty acid and to 0.01 for the membrane fragments. This result indicates that uric acid protects lipids from ozone-induced oxidation.

Animals↗
PubMed1986

Uric acid protection of nucleobases from ozone-induced degradation.

Uric acid has been proposed to be an important antioxidant and free radical scavenger in humans. Of the purine and pyrimidine compounds examined in this study, uric acid showed the greatest susceptibility to ozone-induced degradation. The parent compounds, purine and pyrimidine, were more resistant to ozonation than were the nucleobases. When the degradation of OH-substituted purines was examined, it was found that the more OH groups on the purine ring, the more readily the purine was degraded. Urea and allantoin were identified as degradation products of uric acid. The relative rates of nucleobase degradation in the presence and absence of uric acid were compared. Uric acid protected thymine, guanine, and uracil from degradation by ozone. In this system uric acid was found to protect the nucleobases as effectively as reduced glutathione.

Antioxidants↗
PubMed1985

Scintigraphic dissociation of reticuloendothelial and hepatocyte function in chronic vitamin A hepatotoxicity.

A discordant hepatic uptake between Tc-99m sulfur colloid and Ga-67 citrate has occurred in an adult patient with hepatotoxicity due to hypervitaminosis A. The authors believe this is a scintigraphic phenomenon related to the characteristics of the radiopharmaceuticals used and does not necessarily represent a true dissociation of various cellular functions of the liver.

Chemical and Drug Induced Liver Injury↗
PubMed1982

Screening examination of the larynx and pharynx during upper gastrointestinal panendoscopy.

With the flexible fiberoptic esophagogastroduodenoscopes now in use, the larynx and posterior pharynx can be easily viewed during routine upper gastrointestinal endoscopy. Screening laryngeal-pharyngeal examinations were carried out during 1120 upper gastrointestinal endoscopies. Mean additional examination time was 30 sec. Thirty-nine laryngeal lesions were detected, mostly variants of chronic laryngitis. Two patients had leukoplakia, one of whom on subsequent biopsy revealed squamous cell cancer. The brief additional endoscopic time may result in the detection of early curable neoplasms. Thus a screening laryngeal-pharyngeal examination should be part of each upper gastrointestinal endoscopic examination.

Carcinoma, Squamous Cell↗
PubMed1980

Oesophagitis--a complication of inhaled steroid therapy.

The hazards of steroid therapy, both inhaled and oral, in the asthmatic patient are well recognized. The following case report presents an unusual complication of steroid therapy, namely, that of a concomitant Candida and Herpes simplex oesophagitis occurring in a steroid-dependent 15-year-old asthmatic who had been maintained on inhaled beclomethasone for approximately 15 monts. Oesophagoscopy revealed a 'cottage cheese' appearance of the distal oesophagus. Cultures of the biopsy specimens obtained during oesophagoscopy grew Candida and Herpes simplex virus. Lymphocyte stimulation studies were consistent with a primary cellular response, although the neutralizing antibody titres to the Herpes simplex virus were initially high and remained stable throughout the illness and convalescent period. The patient responded well to oral nystatin therapy and developed no evidence of disseminated herpes. Eleven months after the initial episode, the patient's oropharynx cultured Herpes simplex virus but not Candida. Doctors who care for asthmatic patients need to be aware of the possibility of a herpetic as well as a candidal oesophagitis as a significant complication of inhaled steroid therapy.

Administration, Intranasal↗
PubMedDate not supplied

The application of shear and extensional viscosity measurements to assess the potential of hylan in viscosupplementation.

The shear and extensional viscosity characteristics have been compared for hyaluronan and two samples of a cross-linked derivative, hylan, of different molecular weights. While shear thinning behavior was observed for all systems in shear flow, strain thickening was observed in extensional flow for the relatively dilute systems. However, there was a progressive transition to shear thinning behavior as the polymer concentration was increased. It is evident from the results that the shear flow techniques alone provide an incomplete picture of the rheological properties of these materials and that extensional flow characteristics are potentially dominant. For example, at relatively high deformation rates of 500 s-1 and above, our results show that the extensional viscosities of aqueous solutions of the various polymers are at least two orders of magnitude greater than their corresponding shear flow viscosities. The incremental differences in viscosity with concentration increased with increasing molecular mass of the polymers and were greater in extensional flow than shear flow. These results demonstrate that the dynamic network structure formed by the higher molecular mass hylans offer potentially better physical and mechanical properties for viscosupplementation of diseased osteoarthritis joints compared with the parent hyaluronan.

Humans↗
PubMedDate not supplied

Regional specialization in the eye of the sphingid moth Manduca sexta: blue sensitivity of the ventral retina.

The compound eye of the tobacco hornworm moth Manduca sexta contains green-, blue-, and ultraviolet-sensitive photoreceptors. Electroretinogram spectral-sensitivity measurements were recorded from different regions of the retina in order to broadly map the distribution of the three receptor types. The relative contribution of the three receptors to spectral-sensitivity curves was estimated by fitting theoretical curves based on the absorption spectra of the three rhodopsins. This analysis indicated that the dorsal retina is green and ultraviolet dichromatic, with green-sensitive cells greatly predominating. The ventral retina is trichromatic with a substantial population of blue- and ultraviolet-sensitive receptors. We previously showed that flower visitation for nectar feeding is mediated mainly by blue-sensitive cells. Their localization in the ventral retina seems an appropriate adaptation of the receptor mosaic, since the moths hover above flowers as they feed.

Animals↗
PubMedDate not supplied

Lithium mania: play and learn.

The authors describe an instructional game, Lithium Mania, which they developed to assist in teaching psychiatric clients who were taking lithium about their medication. This game can be used in a formal or recreational setting. The goal of learning made fun was to increase compliance and decrease recidivism.

Games, Experimental↗
PubMedDate not supplied

Why do antenatal attenders decide to have the HIV antibody test?

The aim of the study was to investigate factors influencing the parturient woman's decision to accept or decline the HIV antibody test in the antenatal clinic. Eighty-eight women attending an antenatal clinic, in a central London hospital, for an appointment at 28-32 weeks of pregnancy were given a structured face to face interview. Results indicated that 36% (n = 32) had elected to be tested. Reasons for declining included assumption of no risk, being in a stable relationship, not wanting to think about HIV when pregnant and not wanting to know if HIV positive. Reasons for accepting included fears for health of the baby and fears for own health. 52% (n = 46) had discussed the test with their partner, most of whom had agreed with the woman's decision or left the decision to her. Only 31% of the women were aware they had been automatically tested for syphilis. Knowledge about vertical transmission was poor. Anxiety levels of those tested and those not tested were not significantly different nor did either group differ over time. The groups did not differ on demographic variables, transmission knowledge or perceived likelihood of infection. Most women elected not to be tested and reasons around the decision are very individualistic and varied. HIV testing does not appear to cause anxiety when it is offered on a voluntary basis. Knowledge of routine testing and of vertical transmission is poor and should be the focus of health education intervention.

AIDS Serodiagnosis↗
PubMedDate not supplied

Preoperative HIV antibody testing: the views of surgeons and patients.

Fifty surgeons and 72 preoperative patients in 2 central London hospitals were asked their views on preoperative HIV antibody testing, who is at risk of HIV infection and HIV test counseling. A substantial proportion of both surgeons and preoperative patients, 48% and 54% respectively, supported compulsory HIV antibody testing without patient consent. They believed this should occur as a routine practice prior to surgery. However, surgeons and patients differed in the preoperative patients to be considered for such testing. All surgeons advocating compulsory testing believed that it was only necessary for those patients belonging to high risk groups whilst preoperative patients believed that all patients should be HIV tested prior to surgery. Surgeons and patients also differed in their views on who was at risk of HIV infection. Surgeons believed those at risk to be members of identifiable risk groups whilst patients believed everyone was at risk, especially those engaging in high risk behaviours. Finally, when asked which health professionals they thought should be involved in HIV test counselling, both surgeons and patients agreed that hospital doctors, including surgeons themselves, should take on the responsibility of test counselling. The implications of this and routine HIV antibody testing are discussed.

AIDS Serodiagnosis↗