Supercontinuum as a light source for miniaturized endoscopes.

In this work, we have successfully implemented supercontinuum based illumination through single fiber coupling. The integration of a single fiber illumination with a miniature CMOS sensor forms a very slim and powerful camera module for endoscopic imaging. A set of tests and in vivo animal experiments are conducted accordingly to characterize the corresponding illuminance, spectral profile, intensity distribution, and image quality. The key illumination parameters of the supercontinuum, including color rendering index (CRI: 72%~97%) and correlated color temperature (CCT: 3,100K~5,200K), are modified with external filters and compared with those from a LED light source (CRI~76% & CCT~6,500K). The very high spatial coherence of the supercontinuum allows high luminosity conduction through a single multimode fiber (core size~400µm), whose distal end tip is attached with a diffussion tip to broaden the solid angle of illumination (from less than 10° to more than 80°).

Patterns of combined prescriptions of aspirin-Ginkgo biloba in Taiwan: a population-based study.

BACKGROUND AND OBJECTIVES: Although interactions between aspirin and Ginkgo biloba extract (GBE) have been documented, the extent to which these two drugs are used in combination remains unclear. The aim of this study was to estimate the extent and utilization patterns of combined prescriptions of aspirin and GBE in Taiwan based on an analysis of a nationwide database. METHODS: A representative nationwide sample of 200 000 National Health Insurance (NHI) beneficiaries in Taiwan was used. The prescription details of ambulatory care claims for this sample of beneficiaries for the period 1997-2003 were analysed. The prevalence of aspirin and GBE prescriptions was evaluated. The extent of co-prescription of the two drugs was assessed together with the associated patient characteristics. RESULTS: There was an increase in the number of aspirin prescriptions (from 29 986 out of 2 454 879 (1.2%) in 1997, to 50 614 out of 2 499 605 (2.0%) in 2003). Aspirin was mostly prescribed to patients over 50 years old. The percentage of prescriptions with aspirin increased rapidly from 57% to 84%, among those over 50 years old. The number of prescriptions with GBE also increased from 3039 to 6171 and 78-84% was prescribed to those 50 years or older. During the study period, combined prescriptions of aspirin and GBE dramatically increased four times. Most prescriptions were longer than 14 days and 42.4% of combined prescriptions were found to be at the same ambulatory care visit. CONCLUSION: The findings of this study suggest that there is an increasing trend in co-prescription of aspirin and GBE for Taiwan's elderly population during 1997-2003. This trend is of concern and worthy of note.

Second harmonic generation of biotin and biotin ester microcrystals trapped in optical tweezers with a mode-locked Ti:sapphire laser.

Intense second harmonic generation (SHG) was observed from microcrystals of biotin and biotin ester trapped by optical tweezers, formed with a focused near-infrared pulsed laser beam. The intensity of SHG depends strongly on the states of the microcrystals and the excitation wavelength. Microscopic scanning images of biotin and biotin ester were obtained in high contrast with SHG. Simultaneous trapping and excitation of SHG and two-photon autofluorescence of biotin and biotin ester microcrystals allow us to investigate their structure and optical properties. These optically trapped particles (of submicron size) are useful as nonintrusive microscopic probes for high-resolution studies.

Engagement of inducible nitric oxide synthase at the rostral ventrolateral medulla during mevinphos intoxication in the rat.

We evaluated the relationship between the toxicity induced by the organophosphate mevinphos (Mev) and inducible nitric oxide synthase (iNOS) in the rostral ventrolateral medulla (RVLM), the medullary origin of sympathetic neurogenic vasomotor tone. Adult Sprague-Dawley rats that were anesthetized and maintained with propofol were used. Laser scanning confocal microscopic analysis revealed colocalization of the M2 subtype of muscarinic receptors (M(2)R) and iNOS immunoreactivity in RVLM neurons. Comicroinjection bilaterally of Mev (10 nmol) and artificial cerebrospinal fluid (aCSF) into the RVLM elicited a progressive decline in systemic arterial pressure (SAP) and heart rate. This was accompanied during phase 1 Mev intoxication by an increase in the power density of the very high-frequency (VHF; 5-9 Hz), high-frequency (HF; 0.8-2.4 Hz), low-frequency (LF; 0.25- 0.8 Hz) and very low-frequency (VLF; 0-0.25 Hz) components of SAP signals. Phase 2 exhibited a reversal of the VHF and VLF power to control levels and a further reduction in the power density of both HF and LF components to below baseline. Hypotension and bradycardia promoted by Mev were significantly blunted on coadministration into the RVLM of the selective iNOS inhibitors S-methylisothiourea (250 pmol) or aminoguanidine (250 pmol). Not only was the augmented power density of HF and LF components during phase 1 Mev intoxication further enhanced, the reduced power of these two spectral components during phase 2 was appreciably antagonized. On the other hand, the temporal changes in VHF and VLF power were essentially the same as with coadministration of Mev and aCSF. We conclude that, as a cholinesterase inhibitor, Mev may induce toxicity via nitric oxide produced by iNOS on activation of the M(2)R by the accumulated acetylcholine in the RVLM.

Treatment of distal clavicle fracture using Kirschner wires and tension-band wires.

BACKGROUND: Nonunion frequently follows distal clavicle fracture. Traditional pinning methods using the through acromioclavicular articulation may result in osteoarthritic changes or ankylosis. This study introduces a direct pinning technique in which the acromioclavicular joint is spared. METHODS: Twelve patients with displaced distal clavicle fractures received open reduction and fixation with Kirschner wires (K-wires) and tension-band wires, from May 1996 to March 1997. The indication for surgery was type IIa fracture or fracture with displacement. Unrestricted passive and active range of motion was performed as soon as possible after the operation. Stretching and exertional exercises were permitted after radiographs showed an osseous union and after the implants were removed. RESULTS: Eleven patients achieved osseous union with painless full motion. Union time ranged from 3 to 6 months. One patient suffered from more comminuted fracture because of a fall 2 months after operation. This patient received a revision surgery with distal clavicle resection and coracoclavicle reconstruction. Symptomless ossification around the coracoclavicle ligament was noted on radiographs in one patient. The ossification did not progress after the 9-month follow-up. CONCLUSION: Edwards reported a rate of 45% delayed union and 30% nonunion in type II fractures. Several techniques had been described in the relevant literature. In our practice, fixation with Kirschner wires and tension-band wires has been successful in the treatment for displaced distal clavicle fracture.

Multi-photon fluorescence microscopy--the response of plant cells to high intensity illumination.

Multi-photon fluorescence microscopy has been cited for its advantage in increased depth penetration due to low linear absorption and scattering coefficient of biological specimen in the near infrared (NIR) range. Because of the need of high peak power for efficiently exciting two-photon fluorescence, the relationship between cell damage and peak power has become an interesting and much debated topic in the applications of multi-photon fluorescence microscopy. It is conceivable that at high illumination intensity, non-linear photochemical processes have impacts on cell physiology and viability in ways much different from low illumination in the linear domain. In this article, we discuss some of the issues in two-photon fluorescence microscopy, including the degree of transparency of the specimen, a comparison of single- and two-photon excited fluorescence spectra, and the cell damage under high intensity illumination, using plant cells as a model.

Reentrant two-mirror ring resonator for generation of a single-frequency green laser.

A nonplanar, reentrant two-spherical-mirror ring cavity is demonstrated. It is compact and free of astigmatism. Unidirectional operation is achieved by use of reciprocal and nonreciprocal polarization rotators to differentiate round-trip loss. A single-frequency green laser is generated by intracavity frequency doubling. Amplitude noise as low as 0.25% is achieved.

Streptococcal pyrogenic exotoxin B induces apoptosis and reduces phagocytic activity in U937 cells.

Treatment of U937 human monocyte-like cells with Streptococcus pyogenes led to an induction of apoptosis in these cells. A comparison between the wild-type strain and its isogenic protease-negative mutant indicated that the production of streptococcal pyrogenic exotoxin B (SPE B), a cysteine protease, caused a greater extent of apoptosis in U937 cells. Further study using purified SPE B showed that this protease alone could induce U937 cells to undergo apoptosis, which was characterized by morphologic changes, DNA fragmentation laddering on the gel, and an increase in the percentages of hypodiploid cells. The protease activity of SPE B was required for apoptosis to proceed, since treatment with cysteine protease inhibitor E64 or heat inactivation abrogated this death-inducing effect. The SPE B-induced apoptosis pathway was interleukin-1beta converting enzyme (ICE) family protease dependent. Further experiments showed that the phagocytic activity of U937 cells was reduced by SPE B. Treatment with E64 and heat inactivation both abrogated this phagocytosis-inhibitory effect. Taken together, the present data show that SPE B not only possesses the ability to induce apoptosis in monocytic cells but also helps bacteria to resist phagocytosis by host cells.

Two-photon optical-beam-induced current imaging of indium gallium nitride blue light-emitting diodes.

Epilayers of packaged indium gallium nitride light-emitting diodes (LED's) are characterized by optical-beam-induced current (OBIC) and photoluminescence laser-scanning microscopy through two-photon excitation. Light scattering and absorption in the packaging material and the p-doped top layer of the LED's are greatly reduced as a result of employing a longer excitation wavelength, with energy that is less than the bandgap of the top p layer. Compared with single-photon OBIC, two-photon OBIC imaging not only exhibits superior image quality but also reveals more clearly the characteristics of the epilayers that are being focused on.

Polarization-Dependent Periodic Pulse Oscillation in a Diode-Laser-Pumped and Intracavity Frequency-Doubled Nd:YVO 4 Laser.

We demonstrate that two cross-polarized longitudinal modes can have 50% higher conversion efficiency than two parallel-polarized longitudinal modes in a diode-laser-pumped and intracavity frequency-doubled Nd:YVO(4) laser when operated under periodic pulse oscillation. Through simulations of the rate equations for primary frequency intensities and gains, we also verify that this effect can be attributed to gain competition and complementary conversion coefficient between second-harmonic and sum-frequency generations.

UV curable bioadhesives: copolymers of N-vinyl pyrrolidone.

A series of UV curable bioadhesives was prepared from copolymers of N-vinyl pyrrolidone with four different comonomers: 2-acrylamido methyl 1-propane sulfonic acid, vinyl succinimide, glycidyl acrylate, and 2-isocyanatoethyl methacrylate. The developed bioadhesives demonstrated a fast UV-induced setting with a set time of about 3 min. Bond strength between the bioadhesive and porcine intestine specimen was determined by the peel test. These bioadhesives can provide improved adhesion values up to 4.6 N/m of 180 degrees peel strength compared to five different commercial bioadhesives (values ranging from 0.52 to 3.04 N/m). In addition, the fully hydrated UV curable bioadhesives have shown a high water uptake ranging from 25 to 350 wt% and equilibrium water content ranging from 20 to 100 wt%. Because N-vinyl pyrrolidone is a monomer all these copolymers are expected to retain good biocompatibility. Obtained promising results of peel strength and water uptake clearly suggest that the developed bioadhesives have a strong potential for many medical applications such as single-layered hydrogel wound dressings and tissue adhesives.

Gene identification and DNA sequence analysis in the GC-poor 20 megabase region of human chromosome 21.

In contrast to the distal half of the long arm of chromosome 21, the proximal half of approximately 20 megabases of DNA, including 21q11-21 bands, is low in GC content, CpG islands, and identified genes. Despite intensive searches, very few genes and cDNAs have been found in this region. Since the 21q11-21 region is associated with certain Down syndrome pathologies like mental retardation, the identification of relevant genes in this region is important. We used a different approach by constructing microdissection libraries specifically for this region and isolating unique sequence microclones for detailed molecular analysis. We found that this region is enriched with middle and low-copy repetitive sequences, and is also heavily methylated. By sequencing and homology analysis, we identified a significant number of genes/cDNAs, most of which appear to belong to gene families. In addition, we used unique sequence microclones in direct screening of cDNA libraries and isolated 12 cDNAs for this region. Thus, although the 21q11-21 region is gene poor, it is not completely devoid of genes/cDNAs. The presence of high proportions of middle and low-copy repetitive sequences in this region may have evolutionary significance in the genome organization and function of this region. Since 21q11-21 is heavily methylated, the expression of genes in this region may be regulated by a delicate balance of methylation and demethylation, and the presence of an additional copy of chromosome 21 may seriously disturb this balance and cause specific Down syndrome anomalies including mental retardation.

Detailed analysis of a 17q21 microdissection library by sequence bioinformatics and isolation of region-specific clones.

A region-specific microdissection library originating from human chromosome 17q21, was constructed using the MboI linker-adaptor microcloning technique. DNA sequencing of 241 microclones resulted in the identification of 74 novel coding sequences, paralogs of known genes, and known, but previously unmapped, genes or expressed sequence tags that were "virtually" mapped to chromosome 17q21. By pooling the microclones as multiplexed hybridization probes, and by virtue of their origin on 17q21, we were able to identify approximately 150 P1 clones from the human Reference Library Data Base P1 Library that potentially map to chromosome 17q21. Verification of the 17q21 location of 16 P1 clones was accomplished by PCR analysis with STS primer pairs to known 17q21 genes or by FISH. Our results demonstrate the substantial advantage of combining the sequence analysis of microclones with multiplex hybridization strategies for gene discovery and mapping specific gene rich regions of the genome.

Assignment of three human markers in chromosome 21q11 to mouse chromosome 16.

Three unique sequence microclones from human chromosome region 21q11 were assigned to mouse chromosome 16 using a mouse/Chinese hamster cell hybrid 96Az2 containing a single mouse chromosome 16. This comparative mapping provides further homology between human chromosome 21 and mouse chromosome 16 to include the very proximal portion of the long arm of human chromosome 21. Since this part of human chromosome 21 is associated with mental retardation in Down syndrome individuals, its homologous mouse region should also be included in the construction of mouse models for studying Down syndrome phenotypes including mental retardation.

Construction and characterization of three region-specific microdissection libraries for human chromosome 18.

Three region-specific libraries for the entire human chromosome 18 were constructed using microdissection and Mbol linker-adaptor microcloning techniques. The libraries included 18pter-p11.1 (designated 18P library), 18q11.1-q12.3 (18Q1 library), and 18q21.1-qter (18Q2 library). Samples of the microclones from each library were analyzed in detail. The insert sizes ranged between 50-600 bp, with a mean of 180-220 bp for the three libraries. The libraries contained approximately 40-60% microclones with unique sequence inserts. More than 30 unique sequence microclones from each library were analyzed by Southern blot hybridization to demonstrate that they are human specific and were derived from chromosome 18. The human genomic HindIII fragments hybridized to each microclone were determined and microclones cross-hybridized to rodent species were identified. These region-specific libraries and the unique sequence microclones from the libraries are useful reagents for (1) isolating highly polymorphic microsatellite markers for refined linkage analysis, (2) identifying corresponding YAC, BAC or other clones with large inserts for contig assembly and high resolution physical mapping, (3) isolating cDNA clones from the dissected region, and (4) convenient sequencing of the microclones to prepare high density markers and sequence-tagged sites (STSs). Such applications have been demonstrated in a series of similarly constructed microdissection libraries from other regions of the human genome.

Molecular characterization of breakpoints in patients with holoprosencephaly and definition of the HPE2 critical region 2p21.

Holoprosencephaly (HPE) is a common developmental defect involving the brain and face in humans. Cytogenetic deletions in patients with HPE have localized one of the HPE genes (HPE2) to the chromosomal region 2p21. Here we report the molecular genetic characterization of nine HPE patients with cytogenetic deletions or translocations involving 2p21. We have determined the parental origin of the deleted chromosomes and defined the HPE2 critical region between D2S119 and D2S88/D2S391. As a first step towards cloning the HPE2 gene which is crucial for normal brain development we have constructed a YAC contig which spans the smallest region of deletion overlap. Several of these YACs could be identified which span three different 2p21 breakpoints in HPE patients. These YACs narrow the HPE2 critical region to less than 1 Mb and are now being further analyzed to identify the gene causing holoprosencephaly on chromosome 2.

Complete set of eleven region-specific microdissection libraries for human chromosome 2.

The construction and characterization of 11 region-specific libraries for the entire human chromosome 2 have been completed, including four libraries for the short arm and six libraries for the long arm, plus a library for the centromere region. These libraries were constructed using the chromosome microdissection and microcloning technology. Eight libraries have been described previously. This paper presents the final three libraries: 2q21-q22 (designated 2Q5 library), 2q11-q14 (2Q6). and 2p11.1-q11.1 (2CEN). The sizes of the dissected regions ranged between 20 and 30 Mb, with the centromere region of about 4 Mb. All these libraries are large, potentially comprising hundreds of thousands of recombinant microclones. Between 77% and 97% of the microclones were shown to derive from respective dissected regions. From 26 to 66 unique sequence microlones were isolated and characterized in detail for each library. The microclones have short inserts, ranging between 50 and 600 bp, with a mean of about 200 bp. The short inserts can be conveniently sequenced as STSs to provide high density probes for the dissected region. A plasmid sub-library containing at least 20,000 microclones, and usually more, has been prepared from each library and deposited to ATCC for general distribution. The libraries have been used effectively in constructing high resolution physical maps and for contig assembly, as well as in positional cloning of disease genes assigned to the dissected region. Comparing to other chromosomes with detailed mapping information and densely populated probes, chromosome 2 remains largely under-exploited. The availability of a complete set of region-specific libraries and unique sequence microclones from the libraries should provide valuable resources for genome analysis, high resolution physical mapping, region-specific cDNA isolation, and positional cloning for chromosome 2.