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Biomedical subjects

M J Stillman

Publications and source records attributed to M J Stillman.

70 records · Page 4Linked to original sources
PubMed1977

Electron-paramagnetic-resonance studies on a photochemically produced species of horseradish peroxidase compound I.

Strong electron-paramagnetic-resonance signals in the g = 2.00 region were detected after irradiation of horseradish peroxidase Compound I at temperatures of 10 and 100 K. These signals establish the presence of new free-radical species in the peroxidase system. The new species are interpreted in terms of a haem-photosensitized oxidation of the protein's peptide groups close to the Compound I radical site. On warming to room temperature, the radicals decayed irreversibly to a species having a weak asymmetric electron-paramagnetic-resonance signal at 100 K, which could still be observed after incubation at room temperature for more than 1 h.

Cold Temperature↗
PubMed1976

Low temperature magnetic circular dichroism spectra of met- and myoglobin derivatives.

1. Low temperature magnetic circular dichroism spectra of high and low spin derivatives of metmyoglobin and myoglobin have been measured in the Soret and high wavelength regions. 2. The large difference in intensity of the Soret magnetic circular dichroism bands suggest that a correlation exists between the signal intensity and spin state of the heme-iron. 3. From a comparison of the high and low spin sepctra of the myoglobin derivatives it is concluded that oxymyoglobin contains between 10 and 20% of a ferrous high spin component below 100 degrees K.

Animals↗
PubMed1975

Photochemical reactions of horseradish peroxidase compounds I and II at room temperature and 13 degrees K.

Some photochemical reactions of horseradish peroxidase compounds I and II (HRP-I and HRP-II, respectively) have been studied by electronic absorption spectroscopy over the temperature range 297 degrees K-10 degrees K. In glassy matrices below 80 degrees K HRP-I is rapidly converted to hrp-ii when irradiated with low power white light. The native enzyme and HRP-II are not photochemically active at these temperatures with low power irradiation. At room temperature the spontaneous decay of both HRP-I and HRP-II is catalyzed by irradiation with white light. It is shown that the photolysis is dependent upon light in the region 450-320 nm. It is concluded that the HRP-I and HRP-II conformations are closely related with only a low transition energy in the presence of electrons generated by the light. The conversion of HRP-II to HRP is accompanied by large conformational changes and so is inhibited at low temperatures.

Freezing↗
PubMedDate not supplied

Narcolepsy. Signs, symptoms, differential diagnosis, and management.

Narcolepsy is a chronic neurologic disorder characterized by excessive daytime sleepiness and cataplexy and less often by hypnagogic hallucinations and sleep paralysis. While patients report excessive daytime sleepiness and cataplexy as the more frequent symptoms of this condition, excessive daytime sleepiness is generally believed to be the most debilitating. Narcolepsy often is undiagnosed or misdiagnosed for a variety of reasons. Although confirmation of an initial diagnosis requires monitoring of physiologic variables conducted at a sleep center by specialists, the primary care physician has a critical role in the identification and management of this incurable affliction. This article provides recommendations for the diagnosis and management of narcolepsy. The cataplexy associated with narcolepsy can be managed with tricyclic antidepressants. The excessive sleepiness is managed with stimulants but newer agents, such as modafinil, which will be marketed as Provigil, and selegiline hydrochloride, with fewer adverse effects and less abuse potential, may offer means of promoting daytime wakefulness. Groups such as the National Sleep Foundation, Washington, DC, and the Narcolepsy Network, Cincinnati, Ohio, can provide patients with needed support and information.

Diagnosis, Differential↗
PubMedDate not supplied

The role of exercise in rehabilitation for patients with end-stage renal disease.

End-stage renal disease (ESRD) is a major health problem in the United States. Many patients with ESRD experience a decline in physical functioning as a result of the disease process and its associated sequelae. Cardiovascular changes, anemia, and skeletal muscle weakness contribute significantly to this decreased capacity, leading, in many instances, to a primarily sedentary lifestyle. Studies conducted on the effectiveness of exercise training for patients with ESRD reveal numerous physiological and psychological benefits, particularly when training is continued for several months. However, the number of structured exercise programs available as part of a rehabilitation program for ESRD patients is limited. This article provides an overview of the role of exercise for patients with renal disease, and a case study illustrates how nurses, in collaboration with the interdisciplinary team, can be effective in preventing continued deconditioning and in maintaining a more positive outlook in patients with ESRD.

Adult↗
PubMedDate not supplied

Tyrosine administration prevents hypoxia-induced decrements in learning and memory.

Exposure to hypobaric hypoxia rapidly produces decrements in learning and memory. Tyrosine, a neurotransmitter precursor, has beneficial behavioral effects when administered to animals and humans exposed to various acute stressors. To determine whether tyrosine would protect rats from the adverse effects of hypobaric hypoxia on spatial reference and working memory, it was administered to 27 male Fischer 344 rats tested in the Morris water maze. Rats were tested starting at 2 and 6 h of an 8 h exposure to a simulated altitude of 5950 m (19,500 ft) or sea level. Tyrosine or placebo was administered 1/2 h prior to each testing session (400 mg/kg, IP). Altitude exposure significantly increased working memory escape latency; treatment with tyrosine reversed this decrement. There was no effect of altitude or tyrosine on reference memory. There were also no treatment-related differences in performance when animals were tested the next day at sea level. The beneficial effects of tyrosine on working memory performance may be due to a direct effect of tyrosine on memory, alleviation of a hypoxia-induced retardation of learning, or to other central or peripheral effects of this dietary catecholamine precursor.

Altitude↗
PubMedDate not supplied

Women's health beliefs about breast cancer and breast self-examination.

To investigate the nature of women's health beliefs about breast cancer and breast self-examination (BSE) and the extent of BSE practice, a questionnaire was administered to 122 women. Ninety-seven percent (118) scored high in perceived benefits of BSE in reducing the threat of breast cancer and 87 percnet (106) scored high in perceived susceptibility to breast cancer. Forty percent (48) practiced BSE monthly, but over 20 percent of the sample had high beliefs and were nonpracticers. Thus, it cannot be concluded that beliefs cause behavior. Other factors such as embarrassment or religious upbringing influence health beliefs and practices, it was found. A majority of women who did practice BSE, furthermore, were unsure of their ability to detect abnormalities. A separate group of 20 women with a history of breast lumps or cancer surgery had higher susceptibility beliefs, a higher rate of practice, no embarrassment in examining themselves, and more confidence in ability to detect abnormalities than the remainder of the sample.

Adult↗