Biomedical subjects

R W Kessler

Publications and source records attributed to R W Kessler.

3 recordsLinked to original sources

PubMed2005

Multivariate curve resolution: a method of evaluating the kinetics of biotechnological reactions.

In biotechnology, strong emphasis is placed on the development of wet chemical analysis and chromatography to separate target components from a complex matrix. In bioprocessing, the development of single compound biosensors is an important activity. The advantages of these techniques are their high sensitivity and specificity. Inline or online monitoring by means of spectroscopy has the potential to be used as an "all-in-one" analysis technique for biotechnological studies, but it lacks specificity. Multivariate curve resolution (MCR) can be used to overcome this limitation. MCR is able to extract the number of components involved in a complex spectral feature, to attribute the resulting spectra to chemical compounds, to quantify the individual spectral contributions, and to use this quantification to develop kinetic models for the process with or without a priori knowledge. After a short introduction to MCR, two applications are presented. In the first example, the spectral features of hemp are monitored and analysed during growth. MCR provides unperturbed spectra on the activity of, for example, lignin and cellulose during plant development. In a second example, the kinetics of a laccase enzyme-catalysed degradation of aromatic hydrocarbons are calculated from UV/VIS spectra.

Biotechnology↗

PubMed2005

Integrated statistical analysis of cDNA microarray and NIR spectroscopic data applied to a hemp dataset.

Both cDNA microarray and spectroscopic data provide indirect information about the chemical compounds present in the biological tissue under consideration. In this paper simple univariate and bivariate measures are used to investigate correlations between both types of high dimensional analyses. A large dataset of 42 hemp samples on which 3456 cDNA clones and 351 NIR wavelengths have been measured, was analyzed using graphical representations. For this purpose we propose clustered correlation and clustered discrimination images. Large, tissue-related differences are seen to dominate the cDNA-NIR correlation structure but smaller, more difficult to detect, variety-related differences can be found at specific cDNA clone/NIR wavelength combinations.

Algorithms↗

PubMed1979

Munchausen syndrome by proxy: definition of factitious bleeding in an infant by 51Cr labeling of erythrocytes.

The Munchausen syndrome by proxy is a phenomenon in which symptoms of a disease are fabricated by some person other than the patient. This report describes and 8-week-old infant with repetitive bleeding episodes, presumably originating from the upper respiratory tract. Extensive investigations, including angiography, several endoscopies under general anesthesia, and reinfusion of the infant's red cells labeled with 51Cr followed by pulmonary and upper airway scanning, failed to reveal the source of bleeding. Within two weeks after initiation of the 51Cr studies, radioactivity of facial blood from two separate bleeding episodes did not exceed background counts. Simultaneous examination of the infant's capillary blood, however, showed moderate to marked radioactivity. The Rh subtype of the facial blood was cc, whereas the infant's type was Cc. These findings indicated that the facial blood was factitious in origin. No further "bleeding" occurred after this information was presented to the parents. This case represents an unusual example of the Munchausen syndrome by proxy. Awareness of this entity can prevent potentially harmful investigations. Documenting its occurrence and sharing the information with parents in a nonaccusatory manner may prevent future harm to the patient.

Diagnosis, Differential↗