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At least 1,711 records · Page 95Linked to original sources

A large lumen microcatheter for oncologic intervention.

A newly available Tracker-325 catheter (Target Therapeutics, Fremont, CA, USA), modified from the Tracker-18 catheter, has the same outer diameter but a larger lumen. This catheter was used in 15 patients during a 7-month period for superselective arterial catheterization when conventional catheters could not be placed successfully. Arterial embolization (n = 7), chemoembolization (n = 5), and chemoinfusion (n = 3), were performed. The increased luminal diameter of the Tracker-325 allowed an increased flow rate for diagnostic arteriography, accommodated larger embolic particles, and improved the ability to achieve a super-selective position.

Angiography↗

Prophase chromosome movements in living house cricket spermatocytes and their relationship to prometaphase, anaphase and granule movements.

Chromosome and granule movements in meiotic prophase and prometaphase have been studied by time-lapse cinemicrography in live spermatocytes of the house cricket, Acheta domesticus. Chromosome movements in prophase cells, up to one hour or more before breakdown of the nuclear envelope, are described. These movements are frequent but saltatory; are based mostly at chromosome ends but also at kinetochores; occur in very intimate association with the inside of the nuclear envelope; are directed towards and away from the extranuclear centres (centrioles); tend weakly to accumulate bivalents round the two centres and reach a velocity of 0.65 micron/sec. Saltatory movements in granules associated with extranuclear asters are remarkably similar to basic characteristics to the intranuclear chromosome movements. Surprisingly, the chromosome movements (and those granules) are reversably blocked by colcemid (but not lumi-colcemid), and yet occur in the apparent absence of an intranuclear envelope. However, kinetochore movements in very early prometaphase are similar in velocity and other respects to prophase movements; later prometaphase movements are clearly slower, and those of anaphase very much slower still. -The prophase movements suggest a two component model for motion: a non-microtubule, linear force producer together withrotubules with a skeletal, orientational role. Arguably, both these components are also necessary for chromosome movements in prometaphase and anaphase.

Animals↗

Isolation of DNA from single microsurgically excised bands of polytene chromosomes of Chironomus.

A method is described for excising by a glass knife single bands of isolated polytene chromosomes of the salivary glands of Chironomus tentans larvae. DNA strands were isolated from cut-out bands and their contour lengths were determined on electron micrographs. The mean contour length of DNA strands isolated from the double band I-8A was about twice that of the single band I-11B, namely 63 versus 34 micrometers. The described method may be applicable for molecular studies on single bands (e.g., by DNA cloning).

Animals↗

Characterisation of repeated sequences from microdissected B chromosomes of Crepis capillaris.

The B chromosome of Crepis capillaris was isolated from the standard chromosomes by microdissection, and the chromosomal DNA amplified using the degenerate oligonucleotide-primed polymerase chain reaction (DOP-PCR). The PCR product was cloned and a B-specific library created and characterised. Southern and in situ hybridisation analyses of the DOP-PCR product from microdissected B chromosomes confirmed that the B chromosome is composed mainly of sequences also present in the A chromosomes but lacks the main repeated DNA families located in the A-chromosomal heterochromatin. From 100 clones analysed, 12% of the generated B-chromosomal library was shown to be composed of dispersed repeats located in both the A and B chromosomes. No B-specific repeated sequence was detected. One of the most abundant repeated DNAs within the library, the family B134, was further characterised. Repeating units show a sequence similarity range from 69% to 90% and are characterised by their richness in (CA)n repeats. In situ hybridisation revealed that members of this family are dispersed throughout the A and B chromosomes but are more concentrated in the pericentromeric heterochromatin of the B, indicating that the molecular organization of B heterochromatin is different from that of the A chromosomes. Compared with the A chromosomes, the Bs contain about 20,000 copies per micron more of the B134 sequence. This indicates that B134 was amplified on the B chromosome after its origin. The B134 sequences in the B chromosomes have also diverged from those on the A chromosomes. Although the DNA composition of A and B chromosomes is similar, Bs are evolving separately from A chromosomes at the molecular level.

Base Sequence↗

A comparison of acidic glycosaminoglycans in the inner ear and other organs: electrophoretic microanalysis.

Acidic glycosaminoglycans in the ground substance of the membranous cochlear lateral wall, kidney, brain and liver of the guinea pigs were quantitatively and qualitatively analyzed, using electrophoretic microanalysis. The lateral wall of the cochlea showed highest content (0.46 +/- 0.08%/D.W.) of acidic glycosmainoglycans, which were chondroitin sulfate-B (75%), chondroitin sulfate-A (12%) and hyaluronic acid (13%). However, the pattern of these acidic glycosaminoglycans in the inner ear differed from the other organs. A possible role of acidic glycosaminoglycans in the inner ear was discussed.

Animals↗

Microbiochemical approach to liver cell heterogeneity around terminal hepatic venules.

Using lyophilized cryostat sections of liver the activities of alanine aminotransferase, lactate dehydrogenase, and pyruvate kinase were measured using a Lowry technique in the first layer of hepatocytes adjacent to terminal hepatic venules and in the residual parenchymal of the perivenous zone of the acinus in normally fed adult male Wistar rats. Alanine aminotransferase was homogeneously distributed in the two areas measured (ratio hepatocytes adjacent to terminal hepatic venules/residual parenchyma of the perivenous zone: 1.05). Enzyme activities of the lactate dehydrogenase were significantly lower in the hepatocytes adjacent to terminal hepatic venules (ratio: 0.65) and those of the pyruvate kinase significantly higher (ratio: 1.12) than in the residual parenchyma of the perivenous zone indicating liver cell heterogeneity in this zone of the liver acinus.

Alanine Transaminase↗

Engineer's flexible arms: a method of increasing their rigidity.

A simple modification of the attachment of the terminal nipples to the central cable in an engineer's flexible arm is described. By its use, the cable breaks before the nipples are avulsed and greater tension can be employed than with conventional methods of fixation. The resulting increased rigidity much improves the reliability of such arms.

Micromanipulation↗