As part of a study on the implication of elevated Ca2+ levels in the myofibrillar degeneration seen in dystrophic muscle, the content of calmodulin and the activity of Ca2+-activated neutral protease (CANP) have been measured in normal and dystrophic (UM-X7.1) hamsters. Calmodulin levels, expressed as micrograms +/- SEM per gram wet weight were highest in brain (385 +/- 24.7), followed by tongue (93.88 +/- 3.93), heart (42.13 +/- 2.93), and skeletal muscle (31.69 +/- 1.42). No significant increases in calmodulin were observed in the dystrophic tissues thus suggesting that the Ca2+ accumulations observed in dystrophic muscles are unrelated to changes in a calmodulin levels. Because of the complexity of regulation of CANP, a time-dependent study was done using extracts of skeletal, heart, and tongue muscles. Marginal increases in dystrophic CANP were seen in skeletal muscle at all times studied and in the heart and tongue at initial time points only. The data are discussed in terms of rising levels of Ca2+ in muscles of the UM-X7.1 hamster being sufficient to increase CANP activity (without increasing content) to where it causes Z-line dissolution.

Animals↗

PubMedDate not supplied

A water-based triphenyltetrazolium chloride method for the evaluation of green plant tissue viability.

A water-based 2,3,5-triphenyltetrazolium chloride (TTC) partitioning method using n-hexane for the evaluation of green plant tissue viability has been developed. Conventionally, the reduction of TTC to insoluble red-coloured triphenylformazan (TPF) has been used to detect seed, bud, leaf and cultured cell viability. However, the 95% ethanol used to extract TPF also extracts various pigments, such as chlorophyll, from plant tissues which interfere with the absorption of TPF at 485 nm. This new water-based method improves upon the current method by eliminating the interfering pigments in the hexane layer, and by minimising the non-enzymatic oxidation of the sample. When used to evaluate the tissue viability of chillstressed waxapple (Syzygium samarangense) plants, the refined method had a greater sensitivity than the electrolyte leakage method and thus provided a more precise assessment for the physiological state of various plant tissues.

Plant Physiological Phenomena↗

PubMedDate not supplied

Functional implication of human serine/threonine kinase, hAIK, in cell cycle progression.

Protein phosphorylation is involved in many biological activities and plays important roles in cell cycle progression. In the present study, we identified a serine/threonine kinase, hAIK, from human hepatic cells using degenerated polymerase chain reactions with a pair of primers derived from the highly conserved sequence in the catalytic domain of kinases. The full-length hAIK cDNA was then obtained, which contained 403 amino acids and was homologous to Drosophila Aurora2 and yeast Ipl1 proteins. Northern blotting analysis revealed that hAIK was highly expressed in the testis but not in other tissues. Expressions of hAIK drastically increased in cancer tissues/cell lines but not in fibroblasts or nontumorigenic cell lines. The recombinant hAIK protein phosphorylated itself and histone H1; this phosphorylation activity was totally abolished after a point mutation at the catalytic domain (hAIKm). During the interphase cell, hAIK was found mainly in the cytoplasm; during mitosis hAIK accumulated at the centrosomes. In addition, overexpression of hAIK in cancer cell lines (HEK293T and HeLa) appeared to inhibit cell cycle progression. None of these phenomena were observed in hAIKm whose kinase activity was rendered inactive. Our results suggest that hAIK protein/activity might modulate cell cycle progression by interacting with the centrosomes and/or proteins associated with these structures.

Amino Acid Sequence↗

PubMedDate not supplied

Relationship between radioprotective and neuromotor effects of S-2(3-aminopropyl-amino)ethylphosphorothioate (WR-2721) in mice.

The radioprotective and neuromotor effects of WR-2721 were studied in male albino ICR strain mice. The protective activity was evaluated by graded doses of WR-2721 (50-400 mg/kg, IP) against whole body 60Co gamma irradiation at a single maximal lethal threshold dose rad (i.e., 1250 rad). The neuromotor effects of the drug were assayed by its action, at the same dose range as used in the protection assay, on spontaneous motor activity (SMA) and wire hanging performance (WHP). Drug doses were administered 30 min before radiation exposure and neurobehavioral testings. The results showed a dose-dependent increase in radioprotection and an inhibition in the neuromotor tasks. The radioprotective efficacy was seen at doses at which intrinsic neuromotor deficits were detected (100-400 mg/kg). A dose-related parallelism of protective efficacy and neurobehavioral toxicity (i.e., SMA inhibition and WHP disruption) was also observed. The present findings suggest that WR-2721 induces neuromotor dysfunctions along with its radioprotectivity.

Amifostine↗

PubMedDate not supplied

Effect of the radioprotector WR-2721 on operant behavior in the rat.

The effect of WR-2721 on performance maintained by a fixed-ratio 20 (FR-20) schedule for water reinforcement was studied in male Sprague-Dawley rats. Graded doses of WR-2721 (range 25-100 mg/kg) were administered IP immediately prior to a 60 min test session. WR-2721 had a dose dependent monotonic disruptive effect on FR responding, with significant effects at doses of 50, 75 and 100 mg/kg. WR-2721 also decreased postsession water consumption, but only one significant effect at the highest dose (100 mg/kg). Both slopes of the dose-response regression line are parallel in effect. These data indicate that WR-2721 may affect drinking motivation, which could disrupt operant performance, and WR-2721 affects motor behavior at lower doses than those that depress "motivation" to drink. The log dose-probit analysis on the all-or-none disruptive pattern of pause of responding observed from cumulative records disclosed that the slope of this regression line (s = 1.11) was also almost identical to that of reinforcer decrement analyzed from graded dose-response relationship (s = 1.14) and shared the same estimated ED50's (58.5 and 55.6 mg/kg, respectively). A preliminary study using a variety of pharmacological interventions was also carried out to ascertain if the general functional gastrointestinal disorders produced by WR-2721 may subserve the behavioral deficits. Subcutaneous pretreatments with various selective, peripherally active, gastroprotective drugs [cimetidine (30 and 60 mg/kg), pirenzepine (5 and 10 mg/kg) and domperidone (1, 5 and 10 mg/kg)] 30 min prior to challenge with WR-2721 at dose of 100 mg/kg, demonstrated that these drugs did not yield any apparent significant attenuative effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Amifostine↗

PubMedDate not supplied

The effects of 5-HT3 receptor antagonists on cognitive performance in aged monkeys.

The serotonin 5-HT3 receptor antagonists ondansetron and SEC-579 were tested over a wide dose range (0.000001-0.5 mg/kg, PO) for cognitive-enhancing effects in aged rhesus monkeys. Animals were tested on the following cognitive and motor tasks: 1) acquisition of a visual object discrimination; 2) reversal of a visual object discrimination; 3) the delayed response task, a spatial working memory task; and 4) a fine motor task. This study found enhanced acquisition of a visual object discrimination following very low doses (0.000001-0.00001 mg/kg, PO) of either 5-HT3 receptor antagonist. This finding replicates a previous study in marmosets. However, unlike the marmoset research, no reliable improvement was found on the reversal condition. Similarly, no improvement was observed on the delayed response or fine motor tasks. No side effects were observed at any dose, consistent with reports in both animals and humans. These results suggest that 5-HT3 receptor antagonists may be helpful in treating a subset of cognitive functions.

Aging↗

PubMedDate not supplied

Growing-cube isosurface extraction algorithm for medical volume data.

In medical applications, three-dimensional volume data such as CT and MRI are gathered from medical-imaging devices. Marching cube (MC) algorithm is a common routine to extract isosurfaces from volume data. The MC algorithm generates the massive number of triangles to represent an isosurface. It is difficult to render this amount of triangles in real-time on general workstations. In this paper, we present a growing-cube algorithm to reduce the number of triangles generated by the MC algorithm. Growing-cube algorithm uses a surface tracker to avoid exhaustive searching isosurfaces cell-by-cell and, therefore, it saves computation time. During surface tracking, the growing-cube algorithm adaptively merges surfaces contained in the tracked cells to reduce the number of triangles. Surfaces are merged as long as the error is within user-specified error thresholds. Therefore, the proposed algorithm can generate a variable resolution of isosurfaces according to these error parameters.

Algorithms↗

PubMedDate not supplied

Interactive voxel surface rendering in medical applications.

Semi-boundary (SB) data structure is a compact voxel surface representation of the structure from the medical images. It represents only the boundary of the extracted structure and only an opaque object boundary involved in a 3D dataset can be visualized. Its computational complexity is in proportion to the number of SB voxels. In this paper, we propose schemes to reduce the number of projections in two ways. First, in conjunction with neighboring code, we exploit a set of visibility tables to cull some of the invisible SB voxels. Second, we exploit three pass rotations and an incremental approach to quickly determine the projection position for each SB voxel during rendering. With these two combinations, we significantly improve SB rendering performance. As a result, we can achieve an interactive rendering speed on general purpose workstations for our medical applications.

Algorithms↗

PubMedDate not supplied

(+)-CC-1065 produces bending of DNA that appears to resemble adenine/thymine tracts.

Explore the source record for details and available documents.

Adenine↗