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Biomedical subjects

D Koenig

Publications and source records attributed to D Koenig.

7 recordsLinked to original sources
PubMed1992

Syncope in young adults: evidence for a combined medical and psychiatric approach.

To determine the principal causes and effects of syncope in young adults, we prospectively evaluated 197 consecutive patients referred to a Syncope Specialty Clinic, comparing young (age 16-39 years, n = 71), middle-aged (age 40-65 years, n = 70) and elderly (greater than age 65 years, n = 56) patients. Psychiatric aetiologies were significantly more common in young patients (39% vs. 20% in middle-aged, and 3.6% in the elderly; P less than 0.001), while cardiac aetiologies were rare in the young (2.8% vs. 12% in the middle-aged, and 16% in the elderly; P less than 0.04). These differences were still significant after controlling for gender. Because psychiatric causes are so common in young patients, we evaluated hyperventilation as a bedside test for syncope patients and found it to have a positive predictive value of 59% for psychiatric causes of syncope. Syncope interfered with daily activities in 62% of young patients, and resulted in anxiety or depression in 70% of the young (no difference when compared with other age groups). Thus syncope in young adults can be a disabling medical condition requiring a unique medical and psychological approach to diagnosis and treatment.

Adolescent↗
PubMed1989

The purification and characterization of a dextranase from Lipomyces starkeyi.

Dextranase produced by Lipomyces starkeyi was purified 43-fold, by carboxymethyl-Sepharose chromatography followed by agarose gel-filtration chromatography. The purified enzyme showed four bands by SDS/polyacrylamide gel electrophoresis with estimated mass 74 kDa, 71 kDa, 68 kDa and 65 kDa. This preparation exhibited multiple isoelectric points between 5.6 and 6.1. All the isoelectric forms were active and catalytically similar. The dextranase contained a carbohydrate moiety (8%). The physical properties of the enzyme were pH and temperature optima of 5.0 and 55 degrees C, respectively. This dextranase was stable between pH 2.5 and 7.0 at temperatures below 40 degrees C. Lipomyces dextranase was a typical endodextranase with the final product of dextran hydrolysis being isomalto-oligosaccharides from glucose to isomaltotetrose.

Carbohydrates↗
PubMed1983

Mechanisms of immunity to respiratory syncytial virus in cotton rats.

Active immunity and maternally transmitted passive immunity to respiratory syncytial virus (RSV) were studied in cotton rats. Animals infected with respiratory syncytial virus developed complete resistance to pulmonary reinfection, which lasted at least 18 months. Nasal resistance was of shorter duration and began to diminish in 8 months. Pulmonary resistance was transferred by parabiosis, but nasal resistance was not. Adoptive transfer studies with fractionated convalescent blood showed that serum antibody, but not circulating lymphocytes, conferred pulmonary resistance. Immune females conferred antibody to their young prenatally and postnatally, with most of the antibody being transferred via colostrum and milk. Maternally transmitted immunity was more effective in the lungs than in the nose and was transient in both organs. Foster nursing experiments showed colostrum and milk to be the most important routes of immune transfer. Although resistance in infants generally correlated with serum neutralizing antibody levels, several exceptions to this correlation suggested that immune factors other than neutralizing antibody may also play an important role in maternal passive immunity.

Animals↗