[Research advancements of two-dimensional black phosphorus in dentistry]

Two-dimensional black phosphorus (BP) has unique layered structure, excellent photothermal properties, good biocompatibility and high biodegradability. In recent years, it has been found that BP has stable drug loading and light controlled sustained-release drug functions, excellent antibacterial properties and the ability to promote vascular and nerve regeneration in the medicine field, which has a broad application prospect in dentistry. This review elaborates the biological properties of two-dimensional BP and its application progress in dentistry, so as to provide new ideas for the further research and application of two-dimensional BP.

Portable broadband photoacoustic spectroscopy for trace gas detection by quantum cascade laser arrays

We report a portable broadband photoacoustic spectroscopic system for trace gas detection using distributed feedback quantum cascade laser arrays. By sequentially firing 128 lasers, our system acquires a photoacoustic spectrum covering 565cm^-1 (935-1500cm^-1) with a normalized-noise-equivalent-absorption coefficient of 2.5×10^-9cm^-1WHz^-1/2. The firing sequence that determines when and which laser to activate is programmable, which enables frequency-multiplexing excitation. For demonstration, 12 lasers are modulated simultaneously at distinct frequencies, and a photoacoustic spectrum is acquired within 13 ms. The compactness (28cm×17cm×13cm, 3.5 kg) and low power consumption enable convenient installation for on-site monitoring.

Imaging of demineralized enamel in intact tooth by epidetected stimulated Raman scattering microscopy

Stimulated Raman scattering microscopy (SRS) was deployed to quantify enamel demineralization in intact teeth. The surfaces of 15 bovine-enamel blocks were divided into four equal-areas, and chemically demineralized for 0, 8, 16, or 24 h, respectively. SRS images (spectral coverage from ∼850 to 1150  cm  -  1) were obtained at 10-μm increments up to 90  μm from the surface to the dentin-enamel junction. SRS intensities of phosphate (peak: 959  cm  -  1), carbonate (1070  cm  -  1), and water (3250  cm  -  1) were measured. The phosphate peak height was divided by the carbonate peak height to calculate the SRS-P/C-ratio, which was normalized relative to 90  μm (SRS-P/C-ratio-normalized). The water intensity against depth decay curve was fitted with exponential decay. A decay constant (SRS-water-content) was obtained. Knoop-hardness values were obtained before (SMHS) and after demineralization (SMHD). Surface microhardness-change (SMH-change) [  (  SMHD  -  SMHS  )    /  SMHS] was calculated. Depth and integrated mineral loss (ΔZ) were determined by transverse microradiography. Comparisons were made using repeated-measures of analysis of variance. For SRS-P/C-ratio-normalized, at 0-μm (surface), sound (0-h demineralization) was significantly higher than 8-h demineralization and 24-h demineralization; 16-h demineralization was significantly higher than 24-h demineralization. For SRS-water-content, 24-h demineralization was significantly higher than all other demineralization-groups; 8-h demineralization and 16-h demineralization were significantly higher than 0-h demineralization. SRS-water-content presented moderate-to-strong correlation with SMH-change and weak-to-moderate correlation with depth. These results collectively demonstrate the potential of using SRS microscopy for in-situ chemical analysis of dental caries.

High-Speed Spectroscopic Transient Absorption Imaging of Defects in Graphene

Graphene grain boundaries (GBs) and other nanodefects can deteriorate electronic properties. Here, using transient absorption (TA) microscopy we directly visualized GBs by TA intensity increase due to change in density of state. We also observed a faster decay due to defect-accelerated carrier relaxation in the GB area. By line-illumination and parallel detection, we increased the TA intensity imaging speed to 1000 frames per second, which is 6 orders of magnitude faster than Raman microscopy. Combined with a resonant optical delay tuner which scans a 5.3 ps temporal delay within 92 μs, our system enabled spectroscopic TA imaging, at a speed of 50 stacks per second, to probe and characterize graphene nanodefects based on the TA decay rate. Finally, we demonstrate real-time nondestructive characterization of graphene at a rolling speed of 0.3 m/min, which matches the fastest roll-to-roll manufacturing process reported.

Spectroscopic stimulated Raman scattering imaging of highly dynamic specimens through matrix completion

Spectroscopic stimulated Raman scattering (SRS) imaging generates chemical maps of intrinsic molecules, with no need for prior knowledge. Despite great advances in instrumentation, the acquisition speed for a spectroscopic SRS image stack is fundamentally bounded by the pixel integration time. In this work, we report three-dimensional sparsely sampled spectroscopic SRS imaging that measures ~20% of pixels throughout the stack. In conjunction with related work in low-rank matrix completion (e.g., the Netflix Prize), we develop a regularized non-negative matrix factorization algorithm to decompose the sub-sampled image stack into spectral signatures and concentration maps. This design enables an acquisition speed of 0.8 s per image stack, with 50 frames in the spectral domain and 40,000 pixels in the spatial domain, which is faster than the conventional raster laser-scanning scheme by one order of magnitude. Such speed allows real-time metabolic imaging of living fungi suspended in a growth medium while effectively maintaining the spatial and spectral resolutions. This work is expected to promote broad application of matrix completion in spectroscopic laser-scanning imaging.

Label-Free Vibrational Spectroscopic Imaging of Neuronal Membrane Potential

Detecting membrane potentials is critical for understanding how neuronal networks process information. We report a vibrational spectroscopic signature of neuronal membrane potentials identified through hyperspectral stimulated Raman scattering (SRS) imaging of patched primary neurons. High-speed SRS imaging allowed direct visualization of puff-induced depolarization of multiple neurons in mouse brain slices, confirmed by simultaneous calcium imaging. The observed signature, partially dependent on sodium ion influx, is interpreted as ion interactions on the CH₃ Fermi resonance peak in proteins. By implementing a dual-SRS balanced detection scheme, we detected single action potentials in electrically stimulated neurons. These results collectively demonstrate the potential of sensing neuronal activities at multiple sites with a label-free vibrational microscope.

High-speed stimulated hyperspectral Raman imaging using rapid acousto-optic delay lines

Stimulated Raman scattering (SRS) is a powerful, label-free imaging technique that holds significant potential for medical imaging. To allow chemical specificity and minimize spectral distortion in the imaging of live species, a high-speed multiplex SRS imaging platform is needed. By combining a spectral focusing excitation technique with a rapid acousto-optic delay line, we demonstrate a hyperspectral SRS imaging platform capable of measuring a 3-dB spectral window of ∼200  cm^-1 within 12.8 μs with a scan rate of 30 KHz. We present hyperspectral images of a mixture of two different microsphere polymers as well as live fungal cells mixed with human blood.

Coherent anti-Stokes Raman scattering imaging under ambient light

We demonstrate an ambient light coherent anti-Stokes Raman scattering microscope that allows CARS imaging to be operated under environmental light for field use. The CARS signal is modulated at megahertz frequency and detected by a photodiode equipped with a lab-built resonant amplifier, then extracted through a lock-in amplifier. The filters in both the spectral domain and the frequency domain effectively blocked the room light contamination of the CARS image. In situ hyperspectral CARS imaging of tumor tissue under ambient light is demonstrated.

In Situ and In Vivo Molecular Analysis by Coherent Raman Scattering Microscopy

Coherent Raman scattering (CRS) microscopy is a high-speed vibrational imaging platform with the ability to visualize the chemical content of a living specimen by using molecular vibrational fingerprints. We review technical advances and biological applications of CRS microscopy. The basic theory of CRS and the state-of-the-art instrumentation of a CRS microscope are presented. We further summarize and compare the algorithms that are used to separate the Raman signal from the nonresonant background, to denoise a CRS image, and to decompose a hyperspectral CRS image into concentration maps of principal components. Important applications of single-frequency and hyperspectral CRS microscopy are highlighted. Potential directions of CRS microscopy are discussed.

Spectrometer-free vibrational imaging by retrieving stimulated Raman signal from highly scattered photons

In vivo vibrational spectroscopic imaging is inhibited by relatively slow spectral acquisition on the second scale and low photon collection efficiency for a highly scattering system. Recently developed multiplex coherent anti-Stokes Raman scattering and stimulated Raman scattering techniques have improved the spectral acquisition time down to microsecond scale. These methods using a spectrometer setting are not suitable for turbid systems in which nearly all photons are scattered. We demonstrate vibrational imaging by spatial frequency multiplexing of incident photons and single photodiode detection of a stimulated Raman spectrum within 60 μs. Compared to the spectrometer setting, our method improved the photon collection efficiency by two orders of magnitude for highly scattering specimens. We demonstrated in vivo imaging of vitamin E distribution on mouse skin and in situ imaging of human breast cancerous tissues. The reported work opens new opportunities for spectroscopic imaging in a surgical room and for development of deep-tissue Raman spectroscopy toward molecular level diagnosis.

Denoising Stimulated Raman Spectroscopic Images by Total Variation Minimization

High-speed coherent Raman scattering imaging is opening a new avenue to unveiling the cellular machinery by visualizing the spatio-temporal dynamics of target molecules or intracellular organelles. By extracting signals from the laser at MHz modulation frequency, current stimulated Raman scattering (SRS) microscopy has reached shot noise limited detection sensitivity. The laser-based local oscillator in SRS microscopy not only generates high levels of signal, but also delivers a large shot noise which degrades image quality and spectral fidelity. Here, we demonstrate a denoising algorithm that removes the noise in both spatial and spectral domains by total variation minimization. The signal-to-noise ratio of SRS spectroscopic images was improved by up to 57 times for diluted dimethyl sulfoxide solutions and by 15 times for biological tissues. Weak Raman peaks of target molecules originally buried in the noise were unraveled. Coupling the denoising algorithm with multivariate curve resolution allowed discrimination of fat stores from protein-rich organelles in C. elegans. Together, our method significantly improved detection sensitivity without frame averaging, which can be useful for in vivo spectroscopic imaging.

Microsecond Scale Vibrational Spectroscopic Imaging by Multiplex Stimulated Raman Scattering Microscopy

Real-time vibrational spectroscopic imaging is desired for monitoring cellular states and cellular processes in a label-free manner. Raman spectroscopic imaging of highly dynamic systems is inhibited by relatively slow spectral acquisition on millisecond to second scale. Here, we report microsecond scale vibrational spectroscopic imaging by lock-in free parallel detection of spectrally dispersed stimulated Raman scattering signal. Using a homebuilt tuned amplifier array, our method enables Raman spectral acquisition, within the window defined by the broadband pulse, at the speed of 32 microseconds and with close to shot-noise limited detection sensitivity. Incorporated with multivariate curve resolution analysis, our platform allows compositional mapping of lipid droplets in single live cells, observation of intracellular retinoid metabolism, discrimination of fat droplets from protein-rich organelles in Caenorhabditis elegans, spectral detection of fast flowing tumor cells, and monitoring drug diffusion through skin tissue in vivo. The reported technique opens new opportunities for compositional analysis of cellular compartment in a microscope setting and high-throughput spectral profiling of single cells in a flow cytometer setting.

Laparoscopic Roux-en-Y gastric bypass in a morbidly obese patient with renal transplant: a case report

Renal transplant is the only curative treatment for end-stage renal disease. As diabetes and obesity are the major causes of graft failure and post-transplant complication, it is important to manage obesity in patients with renal transplant. Herein, we report a case of a morbidly obese renal-transplant patient with poorly controlled diabetes who received bariatric surgery. A 34-year-old obese Taiwanese man with type 2 diabetes had end-stage renal disease that had progressed since 2008, when he had commenced hemodialysis (January 2008) and had a renal transplant (July 2008). Because of persistent obesity and poorly controlled diabetes, he received LRYGB at Chiayi Christian hospital on 18 August 2010. In the month that followed, he lost 10 kg. His serum creatinine decreased to 1.11 mg/dL (1.4 mg/dL, preoperative) and his hemoglobin A1c decreased to 8.5% (10.4%, preoperative). These results indicate that, in obese renal transplant patients, LRYGB may be employed to treat obesity, control diabetes and stabilize or improve the renal function.

Observation of spontaneous polarization misalignments in periodically poled crystals using second-harmonic generation microscopy

Periodically poled crystal (PPC) is a key component for nonlinear optical applications. Its poling quality relies largely on successful domain inversion and the alignment of spontaneous polarization (SP) vectors in each domain. Here we report the unexpected observation of bulk second harmonic generation (SHG) in PPC when excitation propagating along its optical axis. Based on its tensorial nature, SHG is highly sensitive to the orientation of SP, and therefore the misalignment of SP in each domain of PPC can be revealed noninvasively by SHG microscopy. This nonlinear imaging modality provides optical sectioning capability with 3D sub-micrometer resolution, so it will be useful for in situ investigation of poling quality in PPC.

A diffraction-limited scanning system providing broad spectral range for laser scanning microscopy

Diversified research interests in scanning laser microscopy nowadays require broadband capability of the optical system. Although an all-mirror-based optical design with a suitable metallic coating is appropriate for broad-spectrum applications from ultraviolet to terahertz, most researchers prefer lens-based scanning systems despite the drawbacks of a limited spectral range, ghost reflection, and chromatic aberration. One of the main concerns is that the geometrical aberration induced by off-axis incidence on spherical mirrors significantly deteriorates image resolution. Here, we demonstrate a novel geometrical design of a spherical-mirror-based scanning system in which off-axis aberrations, both astigmatism and coma, are compensated to reach diffraction-limited performance. We have numerically simulated and experimentally verified that this scanning system meets the Marechal condition and provides high Strehl ratio within a 3 degrees x 3 degrees scanning area. Moreover, we demonstrate second-harmonic-generation imaging from starch with our new design. A greatly improved resolution compared to the conventional mirror-based system is confirmed. This scanning system will be ideal for high-resolution linear/nonlinear laser scanning microscopy, ophthalmoscopic applications, and precision fabrications.

Anaerobic degradation of diethyl phthalate, di-n-butyl phthalate, and di-(2-ethylhexyl) phthalate from river sediment in Taiwan

We investigated anaerobic degradation rates for three phthalate esters (PAEs), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and di-(2-ethylhexyl) phthalate (DEHP), from river sediment in Taiwan. The respective anaerobic degradation rate constants for DEP, DBP, and DEHP were observed as 0.045, 0.074, and 0.027 1/day, with respective half-lives of 15.4, 9.4, and 25.7 days under optimal conditions of 30 degrees C and pH7.0. Anaerobic degradation rates were enhanced by the addition of the surfactants brij 35 and triton N101 at a concentration of 1 critical micelle concentration (CMC), and by the addition of yeast extract. Degradation rates were inhibited by the addition of acetate, pyruvate, lactate, FeCl3, MnO2, NaCl, heavy metals, and nonylphenol. Our results indicate that methanogen, sulfate-reducing bacteria, and eubacteria are involved in the degradation of PAEs.

Anaerobic digestion of polyelectrolyte flocculated waste activated sludge

This work examined how adding one of three polyelectrolyte flocculants (T3052: cationic, T2000: non-ionic, and T1052: anionic) affected the anaerobic digestion of wastewater sludge. Methane production, floc characteristics (morphology and zeta-potential) and process parameters (soluble chemical oxygen demands (SCODs) and reductive potentials) were monitored along the digestion tests. The digestion rates of T2000- and T1052-conditioned sludge resembled that for original sludge. The T3052-flocculated sludge generated methane at a higher rate during the first 6 days of digestion than did the original one. In the following stage, the digestion rate of sludge flocculated with T3052 at dosage exceeding 15 g/kg dried solids declined. For example, at 40 days of digestion the methane production amounts for original, 15 g/kg DS flocculated, and 40 g/kg flocculated sludge were of 136, 105, and 85 g/kg DS, respectively. The role of flocculants could change in different stages of digestion. The dosed polymers had no apparent toxicity to the inoculum used. The changes in SCOD, adenosintriphosphate concentrations, oxidative and reductive potential, and zeta-potentials did not correlate with the noted hindered digestion for T3052-conditioned sludge. Microphotographic observation revealed that the flocs of T3052-conditioned sludge were not only of a large size, but also were resistant to structural deterioration during digestion. Therefore, mass transfer resistance was proposed to account for the hindered digestion efficiency observed for T3052-conditioned sludge.

Hydrogen production from wastewater sludge using a Clostridium strain

Limited data in literature revealed a relatively low hydrogen yield from wastewater sludge, ca. 0.16 mg/g-dried solids, using anaerobic fermentation. We demonstrated in this work a much higher hydrogen yield, around 1.1 mg-H2/g-dried solids using a clostridium strain isolated from the sludge sample. The formed hydrogen would be consumed after passing the peak value at around 30-36 h of fermentation. We examined the effects of employing five different pre-treatments on substrate sludge, but noted no appreciable enhancement in hydrogen yield as commonly expected for methane production. Since a vast amount of organic matters had been released to water after hydrogen fermentation, we externally dosed methanogenic bacteria to the fermented liquor to produce methane. The fermented liquor could produce more methane than the non-fermented sample, indicating that the dosed methanogenic bacteria readily utilized the organic matters derived from the fermentation test.

Using filtrate of waste biosolids to effectively produce bio-hydrogen by anaerobic fermentation

Waste biosolids collected from sewage works is a biomass containing a vast amount of polysaccharides and proteins, and thus is considered a potential substrate for producing hydrogen using anaerobic fermentation. This work demonstrated, contrary to the common assumption, that the solids phase in waste activated biosolids presents extra nutrients for anaerobes; it in fact prohibits effective bio-hydrogen production. Using filtrate after removal of solids from biosolids produces more hydrogen than using the whole biosolids, with the former reaching a level an order of magnitude higher than the literature results.

Producing hydrogen from wastewater sludge by Clostridium bifermentans

Excess wastewater sludge collected from the recycling stream of an activated sludge process is biomass that contains large quantities of polysaccharides and proteins. However, relevant literature indicates that the bio-conversion of wastewater sludge to hydrogen is limited and therefore not economically feasible. This work examined the anaerobic digestion of wastewater sludge using a clostridium strain isolated from the sludge as inoculum. A much higher hydrogen yield than presented in the literature was obtained. Also, the effects of five pre-treatments-ultrasonication, acidification, sterilization, freezing/thawing and adding methanogenic inhibitor-on the production of hydrogen were examined. Freezing and thawing and sterilization increased the specific hydrogen yield by 1.5-2.5 times to that of untreated sludge, while adding an inhibitor and ultrasonication reduced the hydrogen yield.

Occurrence and microbial degradation of phthalate esters in Taiwan river sediments

Concentrations and microbial degradation rates were measured for eight phthalate esters (PAEs) found in 14 surface water and six sediment samples taken from rivers in Taiwan. The tested PAEs were diethyl phthalate (DEP), dipropyl phthalate (DPP), di-n-butyl phthalate (DBP), diphenyl phthalate (DPhP), benzylbutyl phthalate (BBP), dihexyl phthalate (DHP), dicyclohexyl phthalate (DCP), and di-(2-ethylhexyl) phthalate (DEHP). In all samples, concentrations of DEHP and DBP were found to be higher than the other six PAEs. DEHP concentrations in the water and sediment samples ranged from ND to 18.5 microg/l and 0.5 to 23.9 microg/g, respectively; for DBP the concentration ranges were 1.0-13.5 microg/l and 0.3-30.3 microg/g, respectively. Concentrations of DHP, BBP, DCP and DPhP were below detection limits. Under aerobic conditions, average degradation half-lives for DEP, DPP, DBP, DPhP, BBP, DHP, DCP and DEHP were measured as 2.5, 2.8, 2.9, 2.6, 3.1, 9.7, 11.1 and 14.8 days, respectively; under anaerobic conditions, respective average half-lives were measured as 33.6, 25.7, 14.4, 14.6, 19.3, 24.1, 26.4 and 34.7 days. In other words, under aerobic conditions we found that DEP, DPP, DBP, DPhP and BBP were easily degraded, but DEHP was difficult to degrade; under anaerobic conditions, DBP, DPhP and BBP were easily degraded, but DEP and DEHP were difficult to degrade. Aerobic degradation rates were up to 10 times faster than anaerobic degradation rates.

Using ATP bioluminescence technique for monitoring microbial activity in sludge

This study demonstrates, for the first time, that the presence of suspended solids in waste-activated sludge interferes with adenosine triphosphate (ATP) bioluminescence tests. The sludge subject to acid/alkaline treatment represented the test sample. Without consideration of the effect of solid concentrations, one would erroneously estimate the density levels of heterotrophic bacteria in the sludge using ATP data. A light blockage model was proposed to evaluate the luminescence reading without the interference of suspended solids.

No sex and age influence on the expression pattern and activities of human gastric alcohol and aldehyde dehydrogenases

BACKGROUND

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are the principal enzymes responsible for ethanol metabolism in humans. The stomach is involved in the metabolism of alcohol during absorption. Conflicting reports exist with regard to the influence of sex and age on the activity of ADH in the human gastric mucosa. The purpose of the present study was to determine the effects of age and sex on the expression pattern and activities of stomach ADH and ALDH.

METHODS

A total of 115 endoscopic gastric biopsy specimens were investigated from Han Chinese men (n = 70) and women (n = 45) aged 20-79 years with approximately even distribution among 10-year age intervals. The expression patterns of ADH and ALDH were identified by isoelectric focusing, and the activities were assayed spectrophotometrically.

RESULTS

The expression patterns of gastric ADH and ALDH remained unchanged with respect to sex and age. At 33 mM or 500 mM ethanol, pH 7.5, the ADH activities did not differ significantly among the various age groups or between men and women. At 200 microM or 20 mM acetaldehyde, the ALDH activities did not differ significantly in relation to sex and age. No correlations were found between the ADH or ALDH activities at both the high and low substrate concentrations and the ages in men and women.

CONCLUSIONS

The results indicate that there is no significant effect of either sex or age on the expression pattern and activity of ADH and ALDH in the human gastric mucosa. The stomach ADH seems unlikely to account for possible variations in the first-pass metabolism of alcohol with regard to sex and age.

Bacterial morphotypes and early cellular responses in clinically infected and non-infected sites after combination therapy of guided tissue regeneration and allograft

OBJECTIVES

To compare the bacterial morphotypes and early cellular responses in periodontally treated sites with and without pus formation after a combination of guided tissue regeneration (GTR) and allograft therapy.

METHODS

45 subjects with 80 sites having periodontal lesions with moderate to deep pockets and angular bone defects participated. 28 treated sites in 25 patients were included in the studies. 14 sites suffered from symptoms and signs of infection with pus formation during the healing period were assigned to the pus (P) group. Another 14 sites had asymptomatic healing and were assigned to the non-pus (NP) group. The GTR membranes were retrieved 4-6 weeks after surgery and processed for SEM examination. The bacterial morphotypes on the membranes were observed and photographed. Bacterial adhesion score (BAS, 0-5) and the presence of leukocytes and fibroblasts were estimated from photographs.

RESULTS

The results showed that large numbers of bacteria (high BAS) were present on both sides of the coronal 2/3 of the membrane in both groups, irrespective of clinical conditions. At the apical 1/3 of the membrane, moderate numbers of bacteria were still found on the outer side in the P group. The BAS of rod-shaped bacteria were significantly higher in the P group than that of the NP group on the outer coronal 2/3 of the membrane. The frequency of the presence of fibroblasts (18.5%) at the apical 1/3 of the inner (tooth facing) side of the P group was much lower than that of the same location (28.6-29.6%) in the NP group. The presence of leukocytes and fewer numbers of fibroblasts on the GTR membrane were associated with greater BAS for rod- and filament-shaped bacteria.

CONCLUSIONS

GTR membranes are commonly colonized by oral bacteria during retention, even on uncomplicated and tissue covered portions. The overt infection clinically (pus group) of the membrane-allograft treated sites is associated with a significantly elevated BAS of rod-shaped bacteria, and may be closely related to the occurrence of its adverse early healing responses (inflammation, pus formation, fewer fibroblasts and greater accumulation of leukocytes).

Contribution to first-pass metabolism of ethanol and inhibition by ethanol for retinol oxidation in human alcohol dehydrogenase family--implications for etiology of fetal alcohol syndrome and alcohol-related diseases

The alcohol dehydrogenase (ADH) family is involved in the metabolism of both ethanol and retinoids. To quantitatively assess the potential contributions to first-pass metabolism of ethanol and the ethanol interference with retinoid homeostasis, saturation kinetics for ethanol oxidation as well as inhibition kinetics by ethanol for all-trans-retinol oxidation of human class I alpha alpha, beta1beta1, beta2beta2, gamma1gamma1, class II pi pi, class III chi chi, and class IV mu mu were evaluated and compared. Class I and class II ADHs exhibited substrate inhibition with inhibition constants ranging over 250-720 mM (except gamma1gamma1) ethanol. Class IV ADH displayed no appreciable inhibition up to 1 M ethanol. Activity of the class III enzyme (190 nM subunit) was undetectable at 250 mM ethanol. The kinetic simulations indicate that the hepatic pi pi and the gastric mu mu can most effectively contribute to first-pass metabolism of alcohol. The Michaelis constant (Km), turnover number (k(cat)), and catalytic efficiency (k(cat)/Km) for retinol oxidation relative to that for ethanol oxidation in class I, class II, and class IV ADHs ranged over 0.00022-1.3, 0.071-0.48, and 0.24-650, respectively. Ethanol was a competitive inhibitor against retinol for class I, II, and IV ADHs with apparent inhibition constants ranging over 0.037-11 mM, indicating that retinoic acid synthesis through the ADH pathways can be tremendously blocked during social/heavy drinking. These findings support the notion that first-pass metabolism of alcohol may occur mainly in the liver through class II pi pi and that cellular retinoid signaling may be perturbed by ethanol via ADH pathways.

Human hepatic alcohol and aldehyde dehydrogenases: genetic polymorphism and activities

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are the major enzymes responsible for the metabolism of ethanol in the body. Both exhibit genetic polymorphism in racial populations. To determine hepatic ethanol metabolizing activities in relation to genetic polymorphism, a total of 23 surgical specimens were investigated. The expression patterns of ADH and ALDH isoenzymes were identified by means of agarose isoelectric focusing, and the activities were assayed spectrophotometrically. At 33 mM ethanol, pH 7.5, the activities in the liver with the homozygous phenotype ADH2 1-1 and ADH2 2-2 and the heterozygous phenotype ADH2 1-2 were determined to be 2.9 +/- 0.7, 16.0 +/- 2.5, and 13.6 +/- 1.0 U/g tissue, respectively. The activities of the ALDH2-active and ALDH2-inactive phenotypes at 200 microM acetaldehyde were determined to be 1.06 +/- 0.13 and 0.71 +/- 0.07 U/g tissue, respectively. These findings indicate that human hepatic ethanol-metabolizing activities differ significantly with respect to polymorphism at both the ADH2 and ALDH2 loci. The results suggest that this genetically determined differential hepatic activity may influence drinking behavior and the development of alcoholism among Orientals.

Human stomach alcohol and aldehyde dehydrogenases: comparison of expression pattern and activities in alimentary tract

BACKGROUND & AIMS

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) are the major enzymes responsible for ethanol metabolism in humans. The human stomach has been documented to be involved in the metabolism of first-passed alcohol. The aim of this study was to determine ethanol-metabolizing activities in the stomach with regard to sex, age, enzyme pattern, and polymorphism.

METHODS

A total of 209 surgical gastric mucosal specimens were investigated. The expression patterns of ADH and ALDH were identified by isoelectric focusing, and the activities were assayed spectrophotometrically.

RESULTS

At 33 or 500 mmol/L ethanol, pH 7.5, the activities in the ADH3 1-1 phenotypic and mu-ADH-expressing mucosal specimens were significantly greater than that in the ADH3 1-2 phenotypic and mu-ADH absent mucosal specimens, respectively. The activities of the ALDH2-inactive phenotypes were significantly lower than that of the ALDH2-active phenotypes at 200 micromol/L acetaldehyde. The gastric ADH and ALDH activities were not significantly different between men and women with respect to age and genetic polymorphism.

CONCLUSIONS

The stomach may contribute only a small portion of the alcohol metabolism observed in humans, and the liver may be the major site for first-pass metabolism. Differential expression patterns of ADH and ALDH in the alimentary tract suggest that different vulnerabilities to ethanol-induced mucosal injury may exist.

Guided tissue regeneration demineralized freeze-dried bone allograft: treatment of furcation defects in mandibular molars

The present study evaluated the effects of combined guided tissue regeneration (GTR) and demineralized freeze-dried bone allograft (DFDBA) therapy on the healing of grade III furcation lesions in mandibular molars of seven periodontitis patients. De novo surgical debridement of furcation roofs by fine diamond bur was introduced. Routine presurgical preparation of teeth and a strict plaque control program were performed for at least six weeks before surgery. A papillary conserved full thickness mucoperiosteal flap was used in all cases. In addition to conventional debridement, odontoplasty was performed on the furcation areas with a diamond bur to eradicate inaccessible fissures or grooves and ensure calculus-free root surfaces. Following debridement, the bony defects were filled with DFDBA and covered with polytetrafluoroethylene (ePTFE) membranes. The flaps were then closed by interproximal sutures coronally positioned through the contact point. The ePTFE membranes were removed 6 to 7 weeks after operation. Clinical parameters such as probing depth (PD), gingival recession (GR), probing attachment level (PAL), tooth mobility (TM), and periapical x-ray were recorded at the baseline and 0, 3, 6, 9, and 12 months after removal of the ePTFE membrane. The results showed a significant increase in the probing attachment level and radiographic evidence of bone fill at the furcation sites. Thus, the addition of fine diamond bur debridement on the furcation in the GTR procedure with DFDBA grafting may be effective in the treatment of grade III furcation involvement.

Trichomonas vaginalis and cervical cancer. A prospective study in China

The relationship between Trichomonas vaginalis infection and cervical cancer was investigated prospectively in a cohort of 16,797 women aged 25 years or more who were followed from 1974 to 1985 within the framework of a cervical screening program in Jingan, China. Personal interviews were conducted by trained interviewers when the women first entered the screening program. At initial screening, 421 (2.51%) women had a positive cytologic diagnosis of T. vaginalis infection. Ninety-nine incident cases of pathologically confirmed squamous cell carcinoma were identified from the cohort, with a total of 140,018 person-years of observation. T. vaginalis infection was found to contribute to the risk of cervical cancer, as determined by crude estimates and after adjustment for potential confounding effects. In a multiple proportional hazards model, the relative risk for cervical cancer was 3.3 (95% confidence interval: 1.5 to 7.4) among women with T. vaginalis infection. Furthermore, in the multivariate analysis, increased risk of cervical cancer was associated with the following factors: number of extramarital sexual partners of both the subjects and their spouses, cigarette smoking, and irregular menstruation. Having a large number of negative Pap smears was associated with lower risk. This study suggests that there might be an association between T. vaginalis infection and the risk of cervical cancer, but only 4 to 5% of cervical cancer in Chinese women may be attributable to T. vaginalis infection.

Genetic polymorphism and activities of human colon alcohol and aldehyde dehydrogenases: no gender and age differences

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isoenzyme patterns from 69 (men, 47; women, 22) surgical colon mucosal specimens were identified by agarose isoelectric focusing. gamma-ADH was found to be the predominant form in the mucosa, whereas only beta-ADH was detectable in the muscle layer. ALDH1, ALDH2, and ALDH3 were detectable in the mucosa, with cytosolic ALDH1 being the major form. At pH 7.5, the ADH activities in the colon mucosae with the homozygous phenotype (exhibiting gamma 1 gamma 1) and the heterozygous phenotype (exhibiting gamma 1 gamma 1, gamma 1, gamma 2, gamma 2, gamma 2) were determined to be 183 +/- 13 and 156 +/- 30 nmol/min/g tissue, respectively. The ALDH activities in the ALDH2-active and ALDH2-inactive phenotypes were determined to be 40.2 +/- 2.3 and 34.6 +/- 2.0 nmol/min/g tissue, respectively. The lack of significant difference in the ALDH activities between these two phenotypic groups can be attributed to the very low expression of the mitochondrial ALDH2 in the colon mucosa. No significant differences in the ADH or the ALDH activities were found between the men and women studied and between the three age groups (20-40, 49-70, and 72-83 years). The ascending, transverse, descending, and sigmoid colons exhibited similar ADH and ALDH activities. The isoenzyme patterns of ADH and ALDH remained unaltered in colon carcinomas, except that a significant reduction of the enzyme activities was found in the cancer tissue as compared with the adjacent normal portions. it is concluded that human colon mucosa exhibits significant amounts of ethanol- and acetaldehyde-oxidizing activities.

Alcohol and aldehyde dehydrogenases in human esophagus: comparison with the stomach enzyme activities

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isoenzymes from surgical esophageal and gastric mucosa were compared by agarose isoelectric focusing. Two prominent ADH forms, designated mu 1 (equivalent to the recently reported mu-form) and mu 2, were expressed in all the 15 esophagus specimens studied, whereas only four of seven examined gastric specimens exhibited a weak to moderately strong mu 1-ADH activity band on the isoelectric focusing gels. pI values of the esophageal mu 1-ADH and mu 2-ADH, and the liver pi-ADH were determined to be 8.61, 8.13, and 8.90, respectively. mu-ADHs exhibited high Km for ethanol (12 mM) and low sensitivity to 4-methylpyrazole inhibition. ALDH3 (BB form) and ALDH1 were the major high- and low-Km aldehyde dehydrogenase in the esophagus, respectively. The ADH and ALDH activities were determined at pH 7.5 to be 751 +/- 78 and 29.9 +/- 3.0 nmol/min/g tissue, respectively (measured at 500 mM ethanol or at 200 microM acetaldehyde; mean +/- SEM; N = 15). The esophageal ADH activity was approximately 4-fold and the ALDH activity 20% that of the stomach enzyme. Because the presence of high activity and high Km mu-ADHs as well as low-activity ALDH1 were found in human esophageal mucosa, it is suggested that there may exist an accumulation of intracellular acetaldehyde during alcohol ingestion. This reactive and toxic metabolite may be involved in the pathogenesis of alcohol-induced esophageal disorders.

Genetic polymorphism and activities of human lung alcohol and aldehyde dehydrogenases: implications for ethanol metabolism and cytotoxicity

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) exhibit genetic polymorphism and tissue specificity. ADH and ALDH isozyme phenotypes from 39 surgical Chinese lung specimens were identified by agarose isoelectric focusing. The identity of the lung beta-ADHs was further demonstrated by their characteristic pH-activity profiles for ethanol oxidation, Km values for NAD and ethanol, and inhibition by 4-methylpyrazole or 1,10-phenanthroline. The beta 2 allele, coding for beta 2 polypeptide, was found to be predominant in the lung specimens studied. The ADH activities in the lungs with the homozygous phenotype ADH2 2-2 (exhibiting beta 2 beta 2) and ADH2 1-1 (exhibiting beta 1 beta 1) and the heterozygous phenotype ADH2 2-1 (exhibiting beta 2 beta 2, beta 2 beta 1, and beta 1 beta 1) were determined to be 999 +/- 77, 48 +/- 17, and 494 +/- 61 nmol/min/g tissue, respectively. Fifty-one percent of the specimens studied lacked the ALDH2 activity band on the isoelectric focusing gels. The activities in the lung tissues with the ALDH2-active phenotype and the inactive phenotype were determined to be 30 +/- 3 and 17 +/- 1 nmol/min/g tissue, respectively. These findings indicate that human pulmonary ethanol-metabolizing activities differ significantly with respect to genetic polymorphism at both the ADH2 and the ALDH2 loci. The results suggest that individuals with high Vmax beta 2-ADH and deficient in low-Km mitochondrial ALDH2, accounting for approximately 45% of the Chinese population, may end up with acetaldehyde accumulation during alcohol consumption, rendering them vulnerable to tissue injury caused by this highly reactive and toxic metabolite.

Stomach and duodenal alcohol and aldehyde dehydrogenase isozymes in Chinese

Alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) isozyme phenotypes were determined in surgical and endoscopic biopsies of the stomach and duodenum by agarose isoelectric focusing. gamma-ADH was found to be the predominant form in the mucosal layer whereas beta-ADH was predominant in the muscular layer. Low-Km ALDH1 and ALDH2 were found in the stomach and duodenum. High-Km ALDH3 isozymes occurred only in the stomach but not in the duodenum. The isozyme patterns of gastric mucosal ALDH2 and ALDH3 remained unchanged in the fundus, corpus, and antrum. The stomach ALDH3 isozymes exhibited a Km value for acetaldehyde of 75 mM, and an optimum for acetaldehyde oxidation at pH 8.5. Since the Km value was high, ALDH3 contributed very little, if any, to gastric ethanol metabolism. The activities of ALDH in the gastric mucosa deficient in ALDH2 were 60-70% of that of the ALDH2-active phenotypes. These results indicate that Chinese lacking ALDH2 activity may have a lower acetaldehyde oxidation rate in the stomach during alcohol consumption.

Identification of a human stomach alcohol dehydrogenase with distinctive kinetic properties

A new form of alcohol dehydrogenase, designated mu-alcohol dehydrogenase, was identified in surgical human stomach mucosa by isoelectric focusing and kinetic determinations. This enzyme was anodic to class I (alpha, beta, gamma) and class II (pi) alcohol dehydrogenases on agarose isoelectric focusing gels. The partially purified mu-alcohol dehydrogenase, specifically using NAD+ as cofactor, catalyzed the oxidation of aliphatic and aromatic alcohols with long chain alcohols being better substrates, indicating a barrel-shape hydrophobic binding pocket for substrate. mu-Alcohol dehydrogenase stood out in high Km values for both ethanol (18 mM) and NAD+ (340 microM) as well as in high Ki value (320 microM) for 4-methylpyrazole, a competitive inhibitor for ethanol. mu-Alcohol dehydrogenase may account for up to 50% of total stomach alcohol dehydrogenase activity and appeared to play a significant role in first-pass metabolism of ethanol in human.

Kinetic evidence for human liver and stomach aldehyde dehydrogenase-3 representing an unique class of isozymes

Substrate and coenzyme specificities of human liver and stomach aldehyde dehydrogenase (ALDH) isozymes were compared by staining with various aldehydes including propionaldehyde, heptaldehyde, decaldehyde, 2-furaldehyde, succinic semialdehyde, and glutamic gamma-semialdehyde and with NAD+ or NADP+ on agarose isoelectric focusing gels. ALDH3 isozyme was isolated from a liver via carboxymethyl-Sephadex and blue Sepharose chromatographies and its kinetic constants for various substrates and coenzymes were determined. Consistent with the previously proposed genetic model for human ALDH3 isozymes (Yin et al., Biochem. Genet. 26:343, 1988), a single liver form and multiple stomach forms exhibited similar kinetic properties, which were strikingly distinct from those of ALDH1, ALDH2, and ALDH4 (glutamic gamma-semialdehyde dehydrogenase). A set of activity assays using various substrates, coenzymes, and an inhibitor to distinguish ALDH1, ALDH2, ALDH3, and ALDH4 is presented. As previously reported in ALDH1 and ALDH2, a higher catalytic efficiency (Vmax/Km) for oxidation of long-chain aliphatic aldehydes was found in ALDH3, suggesting that these enzymes have a hydrophobic barrel-shape substrate binding pocket. Since the Km value for acetaldehyde for liver ALDH3, 83 mM, is very much higher than those of ALDH1 and ALDH2, ALDH3 thus represents an unique class of human ALDH isozymes and it appears not to be involved in ethanol metabolism.

Pregnancy and nasopharyngeal carcinoma: a prognostic evaluation of 27 patients

In order to study the influence of pregnancy on the prognosis of nasopharyngeal carcinoma (NPC), we have retrospectively studied 27 patients who either were discovered to be pregnant during radiotherapy (9 patients, herein abbreviated as concurrent group) or became pregnant after treatment (18 patients, herein abbreviated as subsequent group). This material was collected from the 811 NPC patients treated in our hospital from March 1958 to 1972. The results obtained are presented as follows: Concurrent pregnancy had a disastrous effect on the prognosis of NPC patients giving a five year survival of only 11% (1/9). Of the eight patients who died, six did so within one year of the treatment, five of whom died of distant metastases. This fatal outcome was not altered by any measure we instituted. This adverse influence was not observed in the subsequent group, yet the time of gestation seemed to be relevant to the prognosis. Two of the three patients who became pregnant within one year of the treatment died of disease, those who became pregnant beyond the second year after irradiation had the best prognosis. All seven patients who became pregnant after the second year of treatment survived. The frequency of pregnancy did not influence the prognosis of patients if the conception occurred beyond the second year in the subsequent group. All the five patients who gave birth to two, three or even four children survived for more than five years without any evidence of tumor. A total of 21 children were born to the patients of these two groups. They have been followed regularly for 10 to 20 years. No deformity, or retardation in growth or mentality was discovered, nor was there any evidence of radiation tumor or leukemia observed.

Morphiceptin ( beta-casomorphin (1-4) amide): a peptide opioid antagonist in the field stimulated rat vas deferens

The effect of Morphiceptin (H-Tyr-Pro-Phe-Pro-NH2) on opioid inhibition of field stimulated rat vas deferens (RVD) was studied. The morphiceptin was found to produce a weak inhibition of the twitch response of the RVD. In addition morphiceptin antagonized full agonists acting on the same receptor system (i.e. beta-endorphin selective antagonist for the delta receptor system of RVD by virtue of being a weak partial agonist.

Inhibitory histamine receptors in the rat vas deferens

The effect of histamine on the field stimulated rat vas deferens preparation was studied and compared to mouse vas deferens. Histamine produced a concentration dependent inhibition of rat vas deferens (ID50 14 microM) similar to that seen with mouse vas deferens (ID50 2.4 microM). Unlike mouse however, where only H2 receptors are observed, the histamine inhibition of rat vas deferens was attenuated by both H1, (diphenhydramine) and H2 (cimetidine) antagonists. It is concluded that rat vas deferens contains both H1 and H2 receptor types.