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PubMed1991

[Research on adducts of benzo(a)pyrene and DNA in different cells using synchronous fluorescence spectrophotometry].

The levels of benzo(a)pyrene diolepoxide(BPDE)-DNA adducts were measured in rat and human cells by synchronous fluorescence spectrophotometry. BPDE-DNA adducts detected in human pulmonary alveolar macrophages were related to current smoking habits, in contrast to the adducts found in peripheral blood leukocytes. BP administration to rats produced BPDE-DNA adducts in both liver and lungs. Although small yet repeatable signals were also detected in lung DNA from rats treated for 3 days with tobacco smoke. None of the samples obtained from untreated animals was positive. The detection of BPDE-DNA adducts may be used in biomonitoring and experimental studies for determining of exposure to BP even when applied as a constituent of complex mixtures.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1990

Synchronous fluorescence spectrophotometry of benzo[a]pyrene diol epoxide-DNA adducts in workers exposed to polycyclic aromatic hydrocarbons.

Synchronous fluorescence spectrophotometry (SFS) for benzo[a]pyrene diol epoxide (BPDE)-DNA adducts detects adducts in lymphocyte DNA in some but not all individuals exposed occupationally to polycyclic aromatic hydrocarbons (PAHs). Individual differences in exposure, activation and/or DNA repair can be detected by SFS. Several in vitro and in vivo studies are currently being done to clarify the specificity and usability of SFS as a biomonitoring method for PAH exposure in the work environment.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1989

Chlorophyll precursors in the plasma membrane of a cyanobacterium, Anacystis nidulans. Characterization of protochlorophyllide and chlorophyllide by spectrophotometry, spectrofluorimetry, solvent partition, and high performance liquid chromatography.

Plasma membranes were isolated and separated from thylakoid membranes by discontinuous sucrose density gradient centrifugation of crude membranes prepared by French pressure cell extrusion of lysozyme-treated Anacystis nidulans. Two distinct populations of chlorophyll-free plasma membrane vesicles were obtained exhibiting buoyant densities of 1.087 and 1.100 g/cm3 as opposed to a uniform density of 1.192 g/cm3 for thylakoid membranes. Plasma and thylakoid membranes were characteristically different also with respect to fatty acid and protein composition, cytochrome oxidase activity, and pigment content as analyzed by spectrophotometry, spectrofluorimetry, and high performance liquid chromatography. Apart from carotenoids, chlorophyll a was the only major photosynthetic pigment detected in thylakoid membranes while plasma membranes contained virtually no chlorophyll a but (besides large amounts of carotenoids) protochlorophyllide a and chlorophyllide a as revealed by solvent partition (between n-hexane and acetone or methanol), room and low temperature fluorescence emission and excitation spectra, and analytical separation and identification by high performance liquid chromatography and comparison with authentic standards. The protochlorophyllide in the plasma membrane could be transformed into chlorophyllide in the dark in vitro by incubating the membrane preparation with NADPH; NADP+ effected the reverse transition.

Cell Membrane↗
PubMed1989

Reference interval for the bilirubin excess in cerebrospinal fluid by derivative spectrophotometry.

The value of the bilirubin excess can be a useful aid for recognizing blood from haemorrhage in cerebrospinal fluid. One of the parameters needed for the calculation of the bilirubin excess is the total bilirubin concentration in CSF. A method for measuring total bilirubin in cerebrospinal fluid is presented, based on diazotization of bilirubin according to Jendrassik-Gróf, combined with multiwavelength first derivative spectrophotometry. This bilirubin assay allows determination of total bilirubin concentrations as low as 0.045 +/- 0.002 mumols/l. This method also enables a correction for oxyhaemoglobin interference. The value of the bilirubin excess was calculated for patients (n = 66) not showing any neurological disorder. A reference interval of 0.07 +/- 0.06 mumols/l was calculated for the bilirubin excess.

Bilirubin↗
PubMed1988

Synchronous fluorescence spectrophotometry of benzo[a]pyrene diol epoxide-DNA adducts: a tool for detection of in-vitro and in-vivo DNA damage by exposure to benzo[a]pyrene.

We have applied synchronous fluorescence spectrophotometry (SFS) to study benzo[a]pyrene diol epoxide (BPDE)-DNA adducts in biological samples. Adducts are measured as benzo[a]pyrene (BP) tetrols after acid hydrolysis, and give a peak at 374 nm of emission with a 34-nm wavelength difference. In vitro and in animal studies, there is a positive correlation between the amount of adducts and the BP dose. In cell culture studies, the amount of adducts is increased by increasing both the dose of BP and the time of culture with BP. In preliminary human studies, BPDE-DNA has been found by SFS in placental DNA from some but not all smoking mothers and in blood cell DNA from some individuals in occupationally exposed groups.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1998

BOLD MRI vs. NIR spectrophotometry. Will the best technique come forward?

This paper will discuss the assumptions, strengths and weaknesses of both BOLD imaging and NIR spectrophotometry with respect to monitoring tissue oxygenation. BOLD, or blood oxygen level dependent MRI, is an imaging protocol that is sensitive to specific relaxation rates which are influenced by deoxyhemoglobin. NIRS is capable of providing information on oxyhemoglobin, deoxyhemoglobin and total hemoglobin. Both techniques have inherent assumptions, strengths and weaknesses. NIRS has not been able to provide the spatial sensitivity of BOLD. BOLD may be more difficult to quantify. Currently, these two methods are complementary, providing data that strengthens the interpretation of results from each modality. Recent data indicate that relaxation rates can be used to quantify deoxyhemoglobin in isolated blood and, under specific conditions, there is a strong correlation between deoxyhemoglobin content measured by NIRS and changes in relaxation rates measured by MRI. These data indicate that BOLD imaging has the potential to become an attractive alternative to NIRS.

Animals↗