Effect of room illuminance on monitor black level luminance and monitor calibration

In this article we demonstrate the effect of room illuminance and surrounding monitor black level luminance on image quality for soft copy interpretation. Luminance values of a 10% central target and image quality evaluations and observer performance using a contrast-detail mammography (CDMAM) phantom demonstrate these effects. Our results indicate that high room illuminance has a more damaging effect on image quality when the surrounding monitor luminance is 0% to 5% of the maximum monitor luminance. The effect of room illuminance is less obvious when the surrounding monitor luminance is 20% of the maximum.

Modification of doxorubicin-induced cardiotoxicity: manipulation of the dosage schedule

Modification of the dosing schedule for doxorubicin (DOX) administration represents a possible method of reducing cardiotoxicity from this potent anti-cancer drug, while at the same time maintaining its cytotoxic action. The quantitative effects of modified dosage scheduling have been investigated in a clinically relevant rat model. Cardiotoxicity to DOX was assessed by the degree of reduction in cardiac output at 4-24 weeks after the intravenous administration of DOX. The effects of dose schedules involving three or six small dose administrations, over one and two weeks, were compared with that produced by large single doses of DOX. The total drug dose administered for each schedule was varied in order to establish dose-effect relationships. After a total dose of 3 mg/kg DOX, given as three or six equal small doses, there was a gradual decline in cardiac output in the first 12 weeks after drug administration. Between 12 and 24 weeks, the reduction in cardiac function was relatively stable at between 65% and 85% of that of age-matched controls for three and six equal small doses, respectively. Dose-effect curves for animals showing a > or = 30% reduction in cardiac function after 12 weeks indicated the degree of reduction in cardiac function produced by the modified dose scheduling. Compared with a large single dose, larger total doses were required to produce the same severity of damage. Thus, schedules based on three and six equal small doses resulted in dose modification factor of 1.5 +/- 0.23 and 2.1 +/- 0.28, respectively, when compared with the same effect produced by a large single dose. This appeared to be independent of the severity of cardiac damage, suggesting a simple mathematical relationship between the total acceptable dose of DOX and the dose administered at each intravenous injection. These modifications in the cardiotoxicity of DOX produced by the administration of multiple small doses were of the same order of magnitude as that produced by other methods introduced to reduce anthracycline cardiotoxicity.

Preclinical evaluation of the cardiotoxicity of PK2: a novel HPMA copolymer-doxorubicin-galactosamine conjugate antitumour agent

PK2 is a polymeric anticancer conjugate composed of an N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer backbone and pendant doxorubicin (DOX) linked via a Gly-Phe-Leu-Gly peptide spacer. Additionally galactose residues are present to facilitate liver targeting. To justify clinical evaluation of PK2 it was necessary to determine its late cardiotoxicity compared to that of free DOX. A well standardised Sprague-Dawley rat model was used with either intravenous (i.v.) administration (4, 8 and 12 mg/kg DOX equivalent) or intraperitoneal (i.p.) administration (12, 18, 24 and 36 mg/kg DOX equivalent) of PK2. This variation in the route was due to the limited solubility of PK2 at higher doses. PK2 showed two to three times less acute toxicity (assessed by the maximum reduction in body weight in the first 2 weeks) than free DOX, and both compounds were less toxic when given i.p.. No animals given PK2 i.v. showed clinical signs of cardiotoxicity, the only toxicity seen was abnormal tooth growth (approximately 50% of the animals receiving 12 mg/kg, DOX equivalent). In contrast, several animals receiving free DOX (1-4 mg/kg) i.v. died due to cardiotoxicity in an approximately dose-related manner. All animals receiving free DOX (4 mg/kg) died by 12 weeks. Following i.p. administration of PKZ there were only two late deaths related to cardiotoxicity and these were in the 24 mg/kg DOX equivalent group. All animals receiving PK2 at the highest dose (36 mg/kg DOX equivalent) died within 4 weeks, cardiotoxicity was not the main contributing factor. In this study, PK2 displayed a approximately 5-fold reduction in cardiotoxicity relative to free DOX and this supported the progression of PK2 into early clinical investigation.

Pre-clinical toxicity evaluation of leaf-stalk extractive of Piper betle Linn. in rodents

Studies on pre-clinical toxicity were undertaken to determine the haematological and biochemical changes after administration of alcoholic extract of leaf-stalk of P. betle in rats and mice. Acute and chronic toxicity experiments were performed on mice and rats according to WHO protocol. Different doses of plant extractive were administered for toxicity studies on short and long term basis. Haematological, biochemical profiles and enzymatic studies (transaminases and phosphatases) indicated that the drug (plant extractive) was devoid of toxicity.

Testing optimum viewing conditions for mammographic image displays

The viewbox luminance and viewing room light level are important parameters in a medical film display, but these parameters have not had much attention. Spatial variations and too much room illumination can mask real signal or create the false perception of a signal. This presentation looks at how scotopic light sources and dark-adapted radiologists may identify more real diseases.

Copper doped alkali halides for computed radiography and digital imaging

We report here the results of our x-ray fluorescence, photostimulated luminescence, and time resolved laser spectroscopy studies in KCI:Cu. This material seems to possess some desirable properties for being used as an imaging plate in computed radiography. This is a US government work. There are no restrictions on its use.

Effects of manganese deficiency on soluble apoplastic peroxidase activities and lignin content in needles of Norway spruce (Picea abies)

Apoplastic peroxidase activities were investigated in manganese-deficient and manganese-sufficient needles of field-grown Norway spruce trees (Picea abies L.). In Mn-sufficient needles, two sets of peroxidases, one with an alkaline pI >/= 9 and another with an acidic pI </= 3, were identified using guaiacol or coniferylalcohol as substrates for activity staining after isoelectric focusing in a pH gradient from 3 to 9. The acidic peroxidases were capable of Mn-dependent NADH oxidation and H(2)O(2) formation. Syringaldazine peroxidase activity was not found in apoplastic extracts, but was present in whole-needle extracts. Manganese deficiency did not affect the activity or the isoelectric focusing pattern (pH 3 to 9) of the apoplastic peroxidases. Soluble peroxidase activities from whole-needle extracts were significantly higher in Mn-deficient than in Mn-sufficient needles with all substrates tested. Mn-deficient needles contained slightly less cell wall material than Mn-sufficient needles, but the lignin content was similar. Neither apoplastic peroxidase activity nor lignification was affected by Mn deficiency, suggesting that apoplastic peroxidases are regulated independently from symplastic peroxidases.

Antioxidants and Manganese Deficiency in Needles of Norway Spruce (Picea abies L.) Trees

Chlorotic and green needles from Norway spruce (Picea abies L.) trees were sampled in the Calcareous Bavarian Alps in winter. The needles were used for analysis of the mineral and pigment contents, the levels of antioxidants (ascorbate, glutathione), and the activities of protective enzymes (superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate radical reductase, dehydroascorbate reductase, glutathione reductase). In addition, the activities of two respiratory enzymes (glucose-6-phosphate dehydrogenase, NAD-malate dehydrogenase), which might provide the NADPH necessary for functioning of the antioxidative system, were determined. We found that chlorotic needles were severely manganese deficient (3 to 6 micrograms Mn per gram dry weight as compared with up to 190 micrograms Mn per gram dry weight in green needles) but had a similar dry weight to fresh weight ratio, had a similar protein content, and showed no evidence for enhanced lipid peroxidation as compared with green needles. In chlorotic needles, the level of total ascorbate and the activities of superoxide dismutase, monodehydroascorbate radical reductase, NAD-malate dehydrogenase, and glucose-6-phosphate dehydrogenase were significantly increased, whereas the levels of ascorbate peroxidase, dehydroascorbate reductase, glutathione reductase, and glutathione were not affected. The ratio of ascorbate to dehydroascorbate was similar in both green and chlorotic needles. These results suggest that in spruce needles monodehydroascorbate radical reductase is the key enzyme involved in maintaining ascorbate in its reduced state. The reductant necessary for this process may have been supplied at the expense of photosynthate.

Composition and Properties of Hydrogen Peroxide Decomposing Systems in Extracellular and Total Extracts from Needles of Norway Spruce (Picea abies L., Karst.)

Hydrogen peroxide (H(2)O(2)) scavenging systems of spruce (Picea abies) needles were investigated in both extracts obtained from the extracellular space and extracts of total needles. As assessed by the lack of activity of symplastic marker enzymes, the extracellular washing fluid was free from intracellular contaminations. In the extracellular washing fluid ascorbate, glutathione, cysteine, and high specific activities of guaiacol peroxidases were observed. Guaiacol peroxidases in the extracellular washing fluid and needle homogenates had the same catalytic properties, i.e. temperature optimum at 50 degrees C, pH optimum in the range of pH 5 to 6 and low affinity for guaiacol (apparent K(m) = 40 millimolar) and H(2)O(2) (apparent K(m) = 1-3 millimolar). Needle homogenates contained ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, glutathione reductase, and catalase, but not glutathione peroxidase activity. None of these activities was detected in the extracellular washing fluid. Ascorbate and glutathione related enzymes were freeze sensitive; ascorbate peroxidase was labile in the absence of ascorbate. The significance of extracellular antioxidants for the detoxification of injurious oxygen species is discussed.

Anterior fontanel size in hilly and non-hilly newborns in and around the district of Darjeeling

The sizes of the anterior fontanel were measured for 110 hilly and 130 non-hilly newborns in and around the District of Darjeeling to observe for any significant difference. The mean size of the anterior fontanel for the hilly newborns was 3.35 +/- 1.07 cm and for the non-hilly newborns was 3.80 +/- 1.95 cm. There was a significant difference (p less than 0.05) between the hilly and non-hilly races. Percentile grids for the mean anterior fontanel size were calculated. This study may help to prepare a national standard for the anterior fontanel size.

Effect of different nitrogen sources on the yield of oxalic acid by Sclerotium rolfsii

Of the different sources of nitrogen used for the yield of oxalic acid by parent and X-ray mutated strains of Sclerotium rolfsii, organic nitrogen sources gave better results than inorganic nitrogen sources. Cysteine is the best nitrogen source for the parent and one mutant strain while phenylalanine is for the second one.