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Biomedical subjects

E McDonald

Publications and source records attributed to E McDonald.

18 recordsLinked to original sources
PubMed1992

Homosexuals who are twins. A study of 46 probands.

Forty-six homosexual men and women who were twins took part in a study of their sexuality and that of their co-twin. Discordance for sexual orientation in the monozygotic pairs confirmed that genetic factors are insufficient explanation of the development of sexual orientation. There was a high level of shared knowledge of sexual orientation between members of twin pairs, and a relatively high likelihood of sexual relations occurring with same sex co-twins at some time, particularly in monozygotic pairs. The implications of these results for the study of the origins of sexual orientation and for twin research are discussed.

Adolescent↗
PubMed1992

Multiple sclerosis: common management issues.

Multiple sclerosis, the commonest neurological disease of young Australians, has a wide range of symptoms and may lead to varying degrees of physical and cognitive disability. Characteristically, the disease runs an episodic course, but it may be progressive from the outset. To date, treatments aimed at modifying the disease process have been disappointing, but recognition and management of the symptoms have improved, leading to an improved quality of life for people with multiple sclerosis.

Brain↗
PubMed1992

Synthesis and antitumour activities of quinolone antineoplastic agents.

DNA topoisomerases, found in all prokaryotic and eukaryotic cells, play a key role in controlling the topological state of DNA. Quinolone antibacterial agents have been shown to be inhibitors of DNA gyrase, a bacterial topoisomerase II enzyme. The eukaryotic topoisomerase II is the target of various cytotoxic agents such as adriamycin and etoposide. Recently, several quinolones having C-8 fluoro and C-8 chloro substituents have been found to have cytotoxic activities and to interact with mammalian topoisomerase II. In searching for an antitumour agent of the quinolone class, we identified several quinolones having excellent in vitro cytotoxic activity. A-74932 also possesses good activity in vivo against both systemic tumour and subcutaneously implanted murine solid tumours as well as human tumour xenografts. The chemical synthesis as well as biological properties of A-74932 are described.

Animals↗
PubMed1991

Osteoarthritis and rheumatoid arthritis in elderly patients. Differentiation and treatment.

Osteoarthritis is differentiated from rheumatoid arthritis by age at onset, duration of morning stiffness, pattern of joint involvement, and radiographic findings. Distinguishing between the diseases can be challenging, because they have some symptoms in common. Therapy for osteoarthritis is aimed at relief of symptoms; treatment of active rheumatoid arthritis is more aggressive, aimed at controlling or modifying the disease. Both diseases may cause great pain and disability in elderly patients, so prompt diagnosis and treatment are essential.

Aged↗
PubMed1991

Seborrheic dermatitis in acquired immunodeficiency syndrome.

Cutaneous eruptions are commonly seen in acquired immunodeficiency syndrome (AIDS). Seborrheic dermatitis in this patient population is usually more severe and difficult to diagnose and treat. The butterfly distribution of the rash and the interpretation of the biopsy may suggest a diagnosis of discoid lupus erythematosus, unless the pathologist is aware of the underlying immunodeficiency. We present two cases of patients with documented acquired immunodeficiency syndrome whose initial biopsies were interpreted as discoid lupus but whose cutaneous seborrheic dermatitis actually paralleled human immunodeficiency virus disease activity.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Oral acyclovir for chickenpox.

We report on our experience with acyclovir (Zovirax) capsules for the symptomatic treatment of chickenpox in two children and an adult.

Acyclovir↗
PubMed1991

Dry mouth: diagnosing and treating its multiple causes.

Dry mouth in the elderly is a common occurrence with multiple etiologies. It is not a normal phenomenon of aging and, therefore, an attempt at elucidating its cause should be made. Sjögren's syndrome may occur, and it is diagnosed by labial biopsy. Medications are also frequently associated with dry mouth, and dosages may need to be adjusted or the drug discontinued if symptoms are severe. Strategies for management of dry mouth are explored.

Aged↗
PubMed1979

A study of family practice in Wisconsin.

Studies of family practice in Wisconsin and elsewhere show that the clinical content of family practice has about 20 to 45 patient contacts per day and about two to six diagnoses per patient contact. Seventy-five percent of patient contacts are in the office and on the telephone, 15 to 20 percent in the hospital, and 5 to 10 percent elsewhere. There is a broad array of patient problems. Special Conditions and Examinations Without Illness contain the largest number of patient problems. About 60 percent of patients are female and present more endocrine and genitourinary problems. Men present more trauma, circulatory, and respiratory problems, and less health maintenance care. Well-baby and well-child examinations stop at age 15 years. Pre and postnatal care decline sharply at age 35 years, at which time surgical care increases. Infectious disease and trauma, ranking high in the young, are low in the elderly. Circulatory problems, obesity, diabetes, and arthritis increase greatly with age. There is no major difference in type of patient problems related to town size (ie, population). However, comparative studies may uncover different disease occurrence rates between regions.

Adolescent↗
PubMed1976

Biosynthesis of porphyrins and corrins.

Haem, chlorophyll and vitamin B12 are all derived ultimately from four molecules of the pyrrole porphobilinogen (PBG) and the initial enzyme catalysed condensation of PBG leads to the unsymmetrical type III isomer of uroporphyrinogen. On the basis of straightforward chemical considerations the type I isomer should be formed and so the porphyrinogen-forming enzymes of all living systems must catalyse a highly specific rearrangement process. The nature and chemical mechanism of this rearrangement poses one of the most fascinating problems in the porphyrin field and so it is not surprising that over 20 hypothetical schemes have been proposed to account for it. Analysis of the problem suggested that the incorporation of doubly 13C-labelled precursors into the rearranged macrocyclic rings would give valuable new information on the nature of the rearrangement process. In this approach the meso=bridge atoms are of crucial importance, and several unambiguous syntheses of 13C-labelled pyrroles and porphyrins were developed to allow rigorous n.m.r. assignments to be made, and also to provide substrates for enzymic experiments. Studies carried out with enzymes from both avian blood and from Euglena gracilis have revealed the precise nature of the assembly of four PBG molecules into the type-III macrocycle: it is the same in both systems despite their vastly different evolutionary development. Complementary studies are in progress in order to determine the intermediates involved in the conversion of PBG into uroporphyrinogen III. The synthesis of amino methyl pyrromethanes and their interaction in the presence of PBG with the appropriate enzyme systems are described. It is important for the work to be able to separate not only isomeric pyrromethanes but also the four isomeric coproporphyrins. Powerful methods are described which make use of high pressure liquid chromatography for both types of separation process. Once uroporhyrinogen III has been built enzymically, there is a stepwise enzymic decarboxylation of the four acetic acid residues. A heptacarboxylic porphyrin shown to be a type-III porphyrin is isolated from the action of avian blood enzymes on porphobilinogen. Spectroscopic studies with 13C-labelling limit the possible structures to two and total synthesis of these substances shows that the natural product carries its methyl group on ring D. An isomeric heptacarboxylic porphyrin having its methyl group on ring C is of particular interest in relation to the biosynthesis of vitamin B12. This substance is synthesized together with uroporphyrin III, 14C-labelled specifically in ring C. This latter product is used to settle one of the key questions concerning nature's route to vitamin B12 - that is, does the corrin macrocycle arise from uroporphyrinogen III? Incorporation studies and specific degradations prove specific incorporation of uroporphyrinogen III into cobyrinic acid, which is the known precursor of vitamin B12.

Models, Biological↗
PubMed1976

The relation between physician and patient age in family practice.

A study of 100 selected Wisconsin family physicians demonstrated that younger physicians generally had more contact with younger patients, middle-aged physicians had an even distribution of patient age contacts, and older physicians had more contact with older patients. The increase in older patients became pronounced for 56 to 60-year-old physicians. Generally a ten-year increase in physician age was accompanied by a five-year increase in patient age. The rising average age of the American population, combined with the direct physician-patient age relationship demonstrated here suggest that geriatrics will become increasingly relevant not only in the continuum of medical education but also for the individual practicing physician.

Age Factors↗