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With high efficiency and exceptional beam quality, fiber lasers hold great promise. The 1-µm wavelength makes it possible for them to replace both diode- and lamp-pumped Nd:YAG lasers in the micromachining, automotive and biomedical markets.

Lewis^y carbohydrate antigens are abundant on the surface of many carcinomas. Mab B3 directed against this carbohydrate antigen has been used to make an immunotoxin that is very cytotoxic to cancer cells expressing the Lewis^y antigen. Mab B3 was also used to screen a phage-displayed peptide library and identified a peptide mimicking the Lewis^y epitope. In this report, we demonstrate that the Lewis^y epitope-mimicking peptide induces anti-Lewis^y immune responses in both rabbits and mice. In addition, Lewis^y antigens induce anti-peptide immune responses. These results indicate that carbohydrate-mimicking peptides provide a novel strategy to elicit immune responses for tumor-associated carbohydrates.

On the basis of the efficient substrate for p60^c-src protein tyrosine kinase (PTK) YIYGSFK-NH2 (1) (Km = 55 μM) obtained by combinatorial methods, we have designed and synthesized a series of conformationally and topographically constrained substrate-based peptide inhibitors of this enzyme, which showed IC50 values in the low-micromolar range (1−3 μM). A “rotamer scan” was performed by introducing the four stereoisomers of β-Me(2‘)Nal in the postulated interaction site of the peptide inhibitor 23 (IC50 = 1.6 μM). This substitution led to selective and potent inhibitors of p60^c-src PTK; however, no substantial difference in potency was observed among them. This and the results of the “stereochemical scan” performed at residues 2 and 7 of 3 (peptides 19−21), which form the disulfide bond, may suggest that the enzyme active site does not have rigid topographic requirements and thus is able to achieve important conformational changes to bind the ligand as long as the pharmacophore pattern in the inhibitor is conserved. Two new potent iodo-containing nonphosphorylatable tyrosine analogues were also incorporated into our lead inhibitory sequence 23, producing the most potent inhibitors for p60^c-src PTK identified thus far in our studies. Compounds 29 and 30 exhibit IC50 values of 0.13 and 0.54 μM, respectively. Peptide 29 is 420-fold more potent than the parent peptide 1. Selectivity studies of peptides 23−30 toward p60^c-src, Lyn, and Lck PTK showed in general high Lyn/Src and moderate Lck/Src selectivity ratios.We found that the χ¹ space constraints of the specialized amino acids, introduced at position 3 of the peptide lead 23, were not as important as the configuration of the Cα of that residue to recognize the subtle chemical environment surrounding the active site of Src and Lck PTK, as reflected on the obtained Lck/Src selectivity ratios.

The effects of background gases on the optical emission of the excimer-laser-ablated plume from a brass target have been studied experimentally. It is found that the plume emission can be enhanced significantly in a proper gas ambient. In hydrogen, the highest peak intensity is detected, and in argon, there is a distinctive difference in the pressure-dependent emission between in He and in the other three gases, Ar, N2 and H2. Moreover, the monitored line peak intensity remains unchanged in Ar and N2 and increases in H2 within a distance above the target surface; but in He, the observed peak intensity decreases with distance like in vacuum. Furthermore, the emissions of several more atomic lines of Cu and Zn atoms from the plume are also found to be enhanced in the same manner in gas ambient. Some physical processes involved in the plume expansion and the possible mechanisms for the enhanced emission of the plume in backing gas are discussed.

We have developed a novel method for the preparation of fecal specimens for PCR assays. Approximately 100 mg of solid stool or 200 microliters of liquid fecal sample was thoroughly suspended in 1 ml of water. Fecal debris was removed by low-speed centrifugation (2,800 x g for 2 min). The supernatant was then boiled for 10 min in a water bath and further clarified by high-speed centrifugation (12,000 x g for 5 min). Fifty microliters of the clarified supernatant was then purified by Sepharose CL-6B spin column chromatography, and a portion of the purified supernatant was used for PCR. By this method, stools containing enterotoxigenic Escherichia coli H10407 were amplified by colonization factor antigen I fimbrial gene PCR, with a sensitivity of 100 organisms per reaction. The method was also effective for processing stool specimens for Clostridium difficile toxin A and B gene PCRs. This method is rapid, effective, and simple to perform and will improve the applications of PCR to stool specimens for diagnostic purposes.

The PCR primer set Hp1-Hp2, which amplifies a 109-bp fragment of the 16S rRNA gene of Helicobacter pylori, has been widely used for the detection of H. pylori in clinical specimens. We have examined 34 stool samples and 50 human tissue samples from H. pylori-infected and uninfected patients, five human leukocyte samples, and one human cell line by this PCR method. All of these specimens produced a 109-bp PCR product. When Escherichia coli DNA was used as the template, several nonspecific bands, but not the 109-bp band, were observed. No PCR products were generated when DNA samples from five different fungi were used as templates. These results indicate that this 109-bp PCR product was amplified from the human genome. The 109-bp PCR product generated from various clinical specimens also hybridized with the probe pHp, corresponding to a region internal to the PCR product of Hp1-Hp2. We conclude that the 16S rRNA gene PCR with the primer set Hp1-Hp2 is not specific and cannot be used to detect H. pylori in clinical specimens.

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