Subtracted, unique-sequence, in situ hybridization: experimental and diagnostic applications

Nonrandom chromosomal aberrations, particularly in cancer, identify pathogenic biological pathways and, in some cases, have clinical relevance as diagnostic or prognostic markers. Fluorescence and colorimetric in situ hybridization methods facilitate identification of numerical and structural chromosome abnormalities. We report the development of robust, unique-sequence in situ hybridization probes that have several novel features: 1) they are constructed from multimegabase contigs of yeast artificial chromosome (YAC) clones; 2) they are in the form of adapter-ligated, short-fragment, DNA libraries that may be amplified by polymerase chain reaction; and 3) they have had repetitive sequences (eg, Alu and LINE elements) quantitatively removed by subtractive hybridization. These subtracted probes are labeled conveniently, and the fluorescence or colorimetric detection signals are extremely bright. Moreover, they constitute a stable resource that may be amplified through at least four rounds of polymerase chain reaction without diminishing signal intensity. We demonstrate applications of subtracted probes for the MYC and EWS oncogene regions, including 1) characterization of a novel EWS-region translocation in Ewing's sarcoma, 2) identification of chromosomal translocations in paraffin sections, and 3) identification of chromosomal translocations by conventional bright-field microscopy.     

Mean message delays for two packet-FIFO queueing disciplines

Expressions are derived for the mean message delay, as a function of message length, when data messages of different lengths arrive asynchronously at a trunk and are divided, as they come in, into packets of some maximum length. The packets of different messages are intermingled and are put onto the trunk either from a single first-in-first-out (FIFO) queue, or from a high-priority and a low-priority queue for single-packet and multiple-packet messages, respectively. The results are compared to the case in which messages enter service in order of arrival and each message is served to completion without interruption, so that the mean message delay is independent of message length     

Sigma receptor ligands and imidazoline secretagogues mediate their insulin secretory effects by activating distinct receptor systems in isolated islets

The effects of two potent sigma receptor agonists (+)-3-PPP ((R)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine) and DTG (N,N'-di-(o-tolyl)guanidine) on the insulin secretory responses in rat islets of Langerhans were investigated. Both sigma receptor ligands were able to potentiate the insulin secretory response of islets incubated at 6 mM glucose, in a dose-dependent manner and were also able to reverse the effects of diazoxide on insulin release. When islets were treated with efaroxan, a well-characterised imidazoline insulin secretagogue, and either (+)-3-PPP or DTG together, there was an unexpected and profound absence of stimulation of insulin release as compared to when islets were incubated with each compound alone. Experiments performed with islets where there was desensitization of DTG/sigma receptor or efaroxan/imidazoline binding site mediated responses suggest that at least two distinct receptor systems appear to be involved. The complex interactions of these two classes of drug require further investigation.     

Preferential metabolism of linoleic acid by five-day-old barley shoots

The degradation of exogenous radioactively labeled fatty acids by 5-day-old barley shoots was examined. [1-¹⁴C] Linoleic acid was observed to be degraded 7 times faster than [1-¹⁴C] oleic acid and 5 times faster than [1-¹⁴C] palmitic acid. The pathway of degradation was determined by identifying the water-soluble products and determined to be β-oxidation. During a 15 min incubation, the barley shoots took up 0.91 nmol/g fresh wt of linoleic acid, of which 0.16 nmol/g fresh wt was incorporated into glutamic acid, 0.07 nmol/g fresh wt into succinic acid and 0.002 nmol/g fresh wt into carbohydrates. By 30 min, additional TCA cycle intermediates, especially malic acid, were detected. Palmitic acid and oleic acid were broken down to the same products. The rates of uptake and the distribution of label into lipids were determined. The uptake of label by the tissue was similar for all 3 fatty acid substrates. Label from linoleic, oleic and palmitic acids was found to be incorporated into similar lipids, primarily phosphatidylcholine (PC), and the extent of incorporation was comparable. Although all 3 fatty acid substrates were broken down by β-oxidation, the reason for the more rapid degradation of linoleic acid was not established. It does not appear to be related to uptake of substrate or incorporation of label into lipids.     

Magnetoplumbite-Type Compounds: Further Discussion

Hexagonal magnetoplumbites are probably more common as minerals than has been appreciated. Over several years, we have synthesized a wide variety of these compounds to demonstrate their flexible cation substitution crystal chemistry, which is of importance for their consideration as potential ceramic radwaste hosts.