Biomedical subjects
J Dillon
Publications and source records attributed to J Dillon.
Detection of bityrosine in cataractous human lens protein.
Bityrosine was isolated from the insoluble protein of human cataractous lenses. Identification was based on correspondence with synthetic bityrosine with respect to chromatography, fluorescence, and ultraviolet and mass spectra. It is suggested that the compound may form cross-links with polypeptide chains in old and cataractous lenses, causing significant alteration in native protein structure.
Non-tryptophan fluorescence associated with human lens protein; apparent complexity and isolation of bityrosine and anthranilic acid.
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Identification of beta carbolines isolated from fluorescent human lens proteins.
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Immune serum-mediated cytotoxicity against Trypanosoma rhodesiense.
The metabolic integrity of Trypanosoma rhodesiense can be assessed in vitro by the extent of incorporation of radiolabeled leucine into trichloroacetic acid precipitable material or into material retained after filtration on a glass fiber filter. Incorporation is an approximately linear function of time, and the rate of incorporation is linearly dependent on cell concentration in the presence of normal rat serum. Incorporation is completely prevented if the organisms are reacted wiith fresh serum from animals immunized with gamma-irradiated parasites; the degree of inhibition is a function of the dose of immune serum used. This serum-mediated cytotoxic activity is abrogated by heating the serum, but can be fully restored by addition of fresh rat or guinea pig serum to the heated immune serum. The serum activity arises promptly after one to four immunizing doses of irradiated parasites, falls to lower levels by 1 month, but persists for at least 2(1/2) months, and is unaffected by challenge with viable trypanosomes.
Absolute configurational studies of vicinal glycols and amino alcohols. I. With ni(acac)2.
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Absolute configurational studies of vicinal glycols and amino alcohols. II. With Pr(dpm)3.
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Car starting sequence and seat belt reminders.
Seat belt reminder systems use visual and auditory signals to encourage seat belt use. A sample of drivers reported the order in which they usually performed the operations necessary to enter and start a motor vehicle. They also reported the point at which they fastened their seat belts. The results were used to recommend the point of reminder signal deployment most suited to the existing habits of vehicle drivers.
Asymmetric septal hypertrophy in a large amish kindred.
We report a large Amish kindred in which asymmetric septal hypertrophy (ASH) appeared to segregate as an autosomal dominant gene. This kindred was ascertained through a 3-month-old infant and her father. The striking differences between father and daughter regarding clinical presentation and course exemplify the variable expressivity of this condition. The importance of genetic factors in diagnosis and counseling are discussed. Previous reports of ASH in infants and children are reviewed.
Subxiphoid echocardiography.
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Fulminant hepatitis associated with acquired defect in humoral immunity.
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Letter: How essential are psychiatric services?
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A bioassay of treatment of hemorrhagic shock. I. The roles of blood, Ringer's solution with lactate, and macromolecules (dextran and hydroxyethyl starch) in the treatment of hemorrhagic shock in the anesthetized dog.
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The treatment of hemorrhagic shock.
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UV-B as a pro-aging and pro-cataract factor.
One of the functions of the human lens is filter light between 300-400 nm from reaching the retina. The lens is therefore continually under photooxidative stress. In the young lens the primary absorbing species is the O-beta glucoside of 3-hydroxykynurenine (3-HKG) which has a maximum at 365 nm. Photophysical studies have demonstrated that absorptions by this compound in the short term are relatively benign to the lens, but in the long term can lead to the photochemical loss of 3-HKG with the concomitant yellowing of lens proteins. It will be proposed that part of this yellowing is due to the photochemically induced attachment of 3-HKG to lens proteins. The yellowing of lens proteins leads to a drastic increase in the number of photons absorbed by the lens. This, along with the age-related losses of antioxidants such as GSH will increase the photooxidative stress on the lens. Considering the foregoing and various epidemiological, model and biochemical studies, it can be concluded that light is most likely one of the causative factors in cataractogenesis.
A new approach to measuring the action spectrum for singlet oxygen production by human retinal lipofuscin.
The human retinal pigment epithelial (RPE) layer contains a complex mixture of components called lipofuscin; this mixture forms with age and with various genetic disorders such as Stargardt's disease. Its presence may contribute to retinal deterioration via several mechanisms including photochemical processes. In the lipofuscin mixture, both type I and II mechanisms have been identified, with the latter consisting of the generation of singlet oxygen. Several components of that mixture have been identified, most notably a bis-retinoid pyridinium compound called A2E and its derivatives. Photooxidative studies on the compound A2E have revealed that its dominant photochemical mechanism is via free radical or type I processes. Because singlet oxygen is an important photooxidative intermediate in tissue, its generation in the RPE may contribute to retinal maculopathies. It is therefore necessary to determine which specific component(s) in the lipofuscin mixture produce singlet oxygen upon excitation with light. This was ascertained by evaluating the action spectrum for singlet oxygen production for the whole lipofuscin mixture using time-resolved spectroscopy. Singlet oxygen was generated by excitation of the sample at different wavelengths while maintaining a constant beam energy, and was directly detected by its phosphorescence decay at 1270 nm using a Ge photodiode. The action spectrum for singlet oxygen sensitization by the organic soluble portion of lipofuscin had an absorption maximum at ca 380 nm, which is to the blue of A2E (maximum at 430 nm). Compounds with a similar absorption maximum eluted in the HPLC earlier than A2E and were detected in human lipofuscin. The concentration of this component apparently increased in concentration in human RPE lipofuscin mixture as a function of age up to 90 years old.
Antioxidant properties of melanin in retinal pigment epithelial cells.
The retinal pigment epithelium (RPE) is a monolayer of highly pigmented cells lining the inner aspect of Bruch's membrane. This pigmentation is due to eumelanin and a possible antioxidant role of melanin is reported here. The photo-oxidation of A2E, a constituent of RPE lipofuscin, leads to the sequential addition of up to nine oxygen atoms and/or the addition or loss of two hydrogen atoms. These photo-oxidations were investigated in the presence and absence of either calf or human RPE melanin in A2E-laden RPE cells. It was found that calf melanin was protective against the photo-oxidation of A2E, with an inhibition of oxidation of up to 50% in the case of the addition of two oxygen atoms. Calf melanin was also protective against blue light-induced damage to RPE cells. In addition this ability appears to decrease in humans as they grow older. With aging, a melanin-lipofuscin complex called melanolipofuscin forms. It is suggested that the oxidation or photo-oxidation of A2E in vivo may contribute to the age-related deterioration of the anti-oxidant role of RPE melanin and lead to various retinal disorders, such as age-related macular degeneration.