Biomedical subjects

D Wrobel

Publications and source records attributed to D Wrobel.

7 recordsLinked to original sources

PubMed1985

Polarized photoacoustic, absorption and fluorescence spectra of chloroplasts and thylakoids oriented in polyvinyl alcohol films.

The polarized photoacoustic, absorption and fluorescence spectra of chloroplasts and thylakoids in unstretched and stretched polyvinyl alcohol films were measured. The intensity ratios of fluorescence bands at 674 nm, 700 nm, 730 nm and 750 nm, and the polarized fluorescence excitation spectra are strongly dependent on light polarization and film stretching. In stretched films, thylakoids exhibit predominantly 674 nm emission. The ratio of photoacoustic signal to absorption is different for light polarized parallel and perpendicular to film stretching. This difference is large in the region of chlorophyll a and carotenoids absorption in which the fluorescence excitation spectra are also strongly dependent on light polarization and film stretching. The observed spectral changes are explained by reorientation of pigment molecules influencing the yield of excitation transfer between different pigments.

Acoustics↗

PubMed1984

Changes in motor activity with age and the effects of pharmacologic treatment.

In a previous study the decline in the motor performance of old rats was determined to be differential. In this study, whether, and to what extent, this decline can be pharmacologically influenced was tested. Therefore, 27 month old rats were orally treated with several nootropics and d-amphetamine for six weeks. Food and water intake were determined. The rats were tested on spontaneous activity and on the tilting plane, climbing, and rotarod tests. The results showed that the nootropics only effected pronounced improvements on complex motor tasks such as on the rotarod test. In contrast, amphetamine treatment caused rather negative effects. This could be observed in the motor performance as well as in the food and water intake. Young rats did not have this sort of reaction to amphetamine. The nootropics were all well tolerated. Additionally, it was obvious that the untreated rats also showed a slight improvement in motor performance due to repeated practice.

Aging↗

PubMed1981

Inability to detect hepatitis B surface antigen (HBsAg) in the duodenum of HBsAg-positive persons.

Incubation of hepatitis B surface antigen (HBsAg)-positive serum with duodenal fluid (DF) of normal persons results in marked reduction of immunoreactivity. This was shown to be caused by: (1) interference with radioimmunoassay (RIA) system and (2) actual destruction of HBsAg. The interference in the RIA system could be counteracted by addition of bovine serum and a reproducible detection system of HBsAg in DF was established. DF of HBsAg-positive persons was negative for HBsAg. One HBsAg carrier who had a partial pancreatectomy for an insulinoma had separate cannulae in his bile and pancreatic ducts. Whereas HBsAg could be detected in bile, it was undetectable in pancreatic juice. Incubation of his pancreatic juice with his bile resulted in disappearance of HBsAg. It appears that a factor present in pancreatic juice, or resulting from the interaction of pancreatic juice and bile, results in disappearance of HBsAg immunoreactivity.

Bile↗

PubMed1980

Hepatitis non-A, non-B.

Evidence for the existence of hepatitis non-A, non-B includes epidemiologic data and results of transmission studies indicating the presence of hepatitis that could not be explained by known causative agents. The diagnosis is suggested in patients who have multiple episodes of acute hepatitis or who contract hepatitis after transfusion, hemodialysis or drug abuse. Sporadic cases are common. Three such cases are described to illustrate that the disease is clinically indistinguishable from hepatitis A or B. The diagnosis is based on the absence of serologic markers of hepatitis A and B and of infection by Epstein-Barr virus and cytomegalovirus, or on serologic evidence of previous infection with hepatitis A and B.

Adult↗

PubMed1980

Dichroism and polarized fluorescence of chlorophyll a, chlorophyll c and bacteriochlorophyll a dissolved in liquid crystals.

Three photosynthetic pigments were studied: chlorophyll a, chlorophyll c and bacteriochlorcphyll a in nematic liquid crystal matrixes. The polarized absorption and fluorescence spectra as a function of the electric field have been measured. From the polarized components of the absorption A( parallel) and A( perpendicular) of the pigments in liquid crystals two reduced components A(x) and A(y) are calculated (x and y are the direction of the axis which is going through the second, fourth pyrrol rings, and the first, third rings, respectively). From these results the orientation of chlorophylls in liquid crystals and the configuration of the transition moments in the skeleton of the pigment molecules were determined.

Journal Article↗

PubMed1979

Failure to detect hepatitis B surface antigen (HBsAg) in feces of HBsAg-positive persons.

Since previous studies did not provide conclusive data regarding the presence of hepatitis B surface antigen (HBsAg) in the feces of HBsAg carriers, the feces of 20 HBsAg carriers and six patients with HBsAg-positive active liver disease were examined with use of a reproducible method for concentrating and detecting HBsAg in feces in which bovine serum, which has been shown to protect HBsAg destruction by fecal components, was added to the fecal specimens. HBsAg was not detected in 66 fecal specimens from the 26 HBs-Ag-positive persons. Furthermore, HBsAg could not be detected in the feces of a carrier who had ingested 4 ml of his own serum. This finding suggests that there are factors in the gastrointestinal tract that interfere with the immunoreactivity of the HBsAg and possibly destroy the hepatitis B virus. These findings explain why oral/fecal spread does not play a major role in the transmission of hepatitis B virus.

Carrier State↗

PubMed1978

Hepatitis and hepatitis B surface antigen and antibody in dentists.

Dentists were surveyed regarding a history of hepatitis and the presence in the blood of hepatitis B surface antigen (HBsAg) and antibody (anti-HBs) to determine whether they were at high risk of exposure to hepatitis B virus. Of 288 Canadian dentists 5.2% gave a history of hepatitis after graduation. This proportion is similar to that for 1462 Ontario dentists (6.3%) and that for 3162 accountants (5.1%) who had previously completed a mailed questionnaire. One dentist (0.3%) was HBsAg-positive and 42 (14.6%) were anti-HBs-positive. Of 210 healthy volunteer blood donors matched for age, sex and ethnic origin with the group of dentists none was HBsAg-positive and 2.9% significantly fewer (P less than 0.005), were anti-HBs-positive. Among Ontario blood donors 0.3% were HBsAg-positive and 3% were anti-HBs-positive. Thus, in Canada, dentists are not at increased risk of acquiring clinical hepatitis or becoming carriers, but they are more likely than other groups to have anti-HBs in the blood. Among dentists from outside Canada a higher proportion had a history of hepatitis (10.3%) and were HBsAg-positive (1.6%), but approximately the same proportion were anti-HBs-positive (15.9%).

Antibodies, Viral↗