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Dr. Samuel  Choi  Md image

Dr. Samuel Choi Md

3901 Lone Tree Way
Antioch CA 94509
925 967-7156
Medical School: Other - 1984
Accepts Medicare: Yes
Participates In eRX: No
Participates In PQRS: Yes
Participates In EHR: No
License #: G65925
NPI: 1932135746
Taxonomy Codes:
2085R0202X

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Awards & Recognitions

About Us

Practice Philosophy

Conditions

Dr. Samuel Choi is associated with these group practices

Procedure Pricing

HCPCS Code Description Average Price Average Price
Allowed By Medicare
HCPCS Code:71250 Description:Ct thorax w/o dye Average Price:$960.75 Average Price Allowed
By Medicare:
$272.08
HCPCS Code:74178 Description:Ct abd & pelv 1/> regns Average Price:$790.74 Average Price Allowed
By Medicare:
$104.56
HCPCS Code:74177 Description:Ct abd & pelv w/contrast Average Price:$595.41 Average Price Allowed
By Medicare:
$94.49
HCPCS Code:74176 Description:Ct abd & pelvis Average Price:$564.00 Average Price Allowed
By Medicare:
$90.40
HCPCS Code:70553 Description:Mri brain w/o & w/dye Average Price:$570.00 Average Price Allowed
By Medicare:
$120.91
HCPCS Code:70450 Description:Ct head/brain w/o dye Average Price:$478.00 Average Price Allowed
By Medicare:
$99.00
HCPCS Code:72148 Description:Mri lumbar spine w/o dye Average Price:$403.00 Average Price Allowed
By Medicare:
$76.48
HCPCS Code:72141 Description:Mri neck spine w/o dye Average Price:$403.00 Average Price Allowed
By Medicare:
$83.90
HCPCS Code:70498 Description:Ct angiography neck Average Price:$403.00 Average Price Allowed
By Medicare:
$84.50
HCPCS Code:71275 Description:Ct angiography chest Average Price:$403.00 Average Price Allowed
By Medicare:
$100.49
HCPCS Code:78452 Description:Ht muscle image spect mult Average Price:$383.00 Average Price Allowed
By Medicare:
$83.97
HCPCS Code:23350 Description:Injection for shoulder x-ray Average Price:$340.00 Average Price Allowed
By Medicare:
$54.41
HCPCS Code:93970 Description:Extremity study Average Price:$314.00 Average Price Allowed
By Medicare:
$35.95
HCPCS Code:73721 Description:Mri jnt of lwr extre w/o dye Average Price:$328.00 Average Price Allowed
By Medicare:
$71.66
HCPCS Code:73221 Description:Mri joint upr extrem w/o dye Average Price:$328.00 Average Price Allowed
By Medicare:
$72.55
HCPCS Code:93880 Description:Extracranial study Average Price:$284.00 Average Price Allowed
By Medicare:
$32.13
HCPCS Code:71260 Description:Ct thorax w/dye Average Price:$299.00 Average Price Allowed
By Medicare:
$59.10
HCPCS Code:70551 Description:Mri brain w/o dye Average Price:$316.00 Average Price Allowed
By Medicare:
$77.04
HCPCS Code:72131 Description:Ct lumbar spine w/o dye Average Price:$282.00 Average Price Allowed
By Medicare:
$48.44
HCPCS Code:78306 Description:Bone imaging whole body Average Price:$276.00 Average Price Allowed
By Medicare:
$44.90
HCPCS Code:71250 Description:Ct thorax w/o dye Average Price:$282.00 Average Price Allowed
By Medicare:
$52.72
HCPCS Code:72125 Description:Ct neck spine w/o dye Average Price:$282.00 Average Price Allowed
By Medicare:
$55.41
HCPCS Code:72192 Description:Ct pelvis w/o dye Average Price:$282.00 Average Price Allowed
By Medicare:
$56.32
HCPCS Code:70450 Description:Ct head/brain w/o dye Average Price:$253.00 Average Price Allowed
By Medicare:
$43.20
HCPCS Code:70486 Description:Ct maxillofacial w/o dye Average Price:$247.00 Average Price Allowed
By Medicare:
$60.71
HCPCS Code:93971 Description:Extremity study Average Price:$209.00 Average Price Allowed
By Medicare:
$23.73
HCPCS Code:76700 Description:Us exam abdom complete Average Price:$182.00 Average Price Allowed
By Medicare:
$43.00
HCPCS Code:76770 Description:Us exam abdo back wall comp Average Price:$177.00 Average Price Allowed
By Medicare:
$39.20
HCPCS Code:G0204 Description:Diagnosticmammographydigital Average Price:$166.00 Average Price Allowed
By Medicare:
$47.15
HCPCS Code:76856 Description:Us exam pelvic complete Average Price:$146.00 Average Price Allowed
By Medicare:
$35.80
HCPCS Code:76830 Description:Transvaginal us non-ob Average Price:$146.00 Average Price Allowed
By Medicare:
$36.90
HCPCS Code:77002 Description:Needle localization by xray Average Price:$138.00 Average Price Allowed
By Medicare:
$29.79
HCPCS Code:76870 Description:Us exam scrotum Average Price:$141.00 Average Price Allowed
By Medicare:
$33.32
HCPCS Code:76705 Description:Echo exam of abdomen Average Price:$131.00 Average Price Allowed
By Medicare:
$30.14
HCPCS Code:76775 Description:Us exam abdo back wall lim Average Price:$131.00 Average Price Allowed
By Medicare:
$30.21
HCPCS Code:76536 Description:Us exam of head and neck Average Price:$130.00 Average Price Allowed
By Medicare:
$29.66
HCPCS Code:G0202 Description:Screeningmammographydigital Average Price:$133.00 Average Price Allowed
By Medicare:
$37.10
HCPCS Code:G0206 Description:Diagnosticmammographydigital Average Price:$133.00 Average Price Allowed
By Medicare:
$37.86
HCPCS Code:74220 Description:Contrast x-ray esophagus Average Price:$107.00 Average Price Allowed
By Medicare:
$24.35
HCPCS Code:76645 Description:Us exam breast(s) Average Price:$110.00 Average Price Allowed
By Medicare:
$28.69
HCPCS Code:72114 Description:X-ray exam of lower spine Average Price:$87.00 Average Price Allowed
By Medicare:
$18.20
HCPCS Code:72110 Description:X-ray exam of lower spine Average Price:$69.00 Average Price Allowed
By Medicare:
$16.81
HCPCS Code:72050 Description:X-ray exam of neck spine Average Price:$68.00 Average Price Allowed
By Medicare:
$16.80
HCPCS Code:74020 Description:X-ray exam of abdomen Average Price:$55.00 Average Price Allowed
By Medicare:
$14.17
HCPCS Code:71101 Description:X-ray exam of ribs/chest Average Price:$55.00 Average Price Allowed
By Medicare:
$14.17
HCPCS Code:73520 Description:X-ray exam of hips Average Price:$54.97 Average Price Allowed
By Medicare:
$14.57
HCPCS Code:72100 Description:X-ray exam of lower spine Average Price:$51.00 Average Price Allowed
By Medicare:
$12.29
HCPCS Code:72080 Description:X-ray exam of trunk spine Average Price:$51.00 Average Price Allowed
By Medicare:
$12.29
HCPCS Code:73564 Description:X-ray exam knee 4 or more Average Price:$49.96 Average Price Allowed
By Medicare:
$12.71
HCPCS Code:72070 Description:X-ray exam of thoracic spine Average Price:$49.00 Average Price Allowed
By Medicare:
$11.94
HCPCS Code:71020 Description:Chest x-ray Average Price:$47.11 Average Price Allowed
By Medicare:
$11.50
HCPCS Code:72170 Description:X-ray exam of pelvis Average Price:$43.76 Average Price Allowed
By Medicare:
$9.63
HCPCS Code:72040 Description:X-ray exam of neck spine Average Price:$46.00 Average Price Allowed
By Medicare:
$12.28
HCPCS Code:73550 Description:X-ray exam of thigh Average Price:$43.19 Average Price Allowed
By Medicare:
$9.60
HCPCS Code:73510 Description:X-ray exam of hip Average Price:$45.00 Average Price Allowed
By Medicare:
$11.93
HCPCS Code:71100 Description:X-ray exam of ribs Average Price:$45.00 Average Price Allowed
By Medicare:
$11.93
HCPCS Code:73562 Description:X-ray exam of knee 3 Average Price:$43.00 Average Price Allowed
By Medicare:
$10.41
HCPCS Code:73030 Description:X-ray exam of shoulder Average Price:$43.00 Average Price Allowed
By Medicare:
$10.42
HCPCS Code:73590 Description:X-ray exam of lower leg Average Price:$41.04 Average Price Allowed
By Medicare:
$9.27
HCPCS Code:73080 Description:X-ray exam of elbow Average Price:$41.00 Average Price Allowed
By Medicare:
$9.29
HCPCS Code:73060 Description:X-ray exam of humerus Average Price:$41.00 Average Price Allowed
By Medicare:
$9.29
HCPCS Code:73630 Description:X-ray exam of foot Average Price:$40.00 Average Price Allowed
By Medicare:
$8.86
HCPCS Code:73110 Description:X-ray exam of wrist Average Price:$40.00 Average Price Allowed
By Medicare:
$9.29
HCPCS Code:73130 Description:X-ray exam of hand Average Price:$40.00 Average Price Allowed
By Medicare:
$9.29
HCPCS Code:73610 Description:X-ray exam of ankle Average Price:$40.00 Average Price Allowed
By Medicare:
$9.29
HCPCS Code:74000 Description:X-ray exam of abdomen Average Price:$40.00 Average Price Allowed
By Medicare:
$9.65
HCPCS Code:73560 Description:X-ray exam of knee 1 or 2 Average Price:$39.00 Average Price Allowed
By Medicare:
$10.06
HCPCS Code:71010 Description:Chest x-ray Average Price:$37.10 Average Price Allowed
By Medicare:
$9.64
HCPCS Code:73660 Description:X-ray exam of toe(s) Average Price:$31.00 Average Price Allowed
By Medicare:
$6.99
HCPCS Code:77052 Description:Comp screen mammogram add-on Average Price:$11.00 Average Price Allowed
By Medicare:
$3.19
HCPCS Code:77051 Description:Computer dx mammogram add-on Average Price:$11.00 Average Price Allowed
By Medicare:
$3.19
HCPCS Code:Q9967 Description:LOCM 300-399mg/ml iodine,1ml Average Price:$1.00 Average Price Allowed
By Medicare:
$0.12

HCPCS Code Definitions

77051
Computer-aided detection (computer algorithm analysis of digital image data for lesion detection) with further review for interpretation, with or without digitization of film radiographic images; diagnostic mammography (List separately in addition to code for primary procedure)
76856
Ultrasound, pelvic (nonobstetric), real time with image documentation; complete
78306
Bone and/or joint imaging; whole body
74020
Radiologic examination, abdomen; complete, including decubitus and/or erect views
73660
Radiologic examination; toe(s), minimum of 2 views
23350
Injection procedure for shoulder arthrography or enhanced CT/MRI shoulder arthrography
70551
Magnetic resonance (eg, proton) imaging, brain (including brain stem); without contrast material
72170
Radiologic examination, pelvis; 1 or 2 views
G0202
Screening mammography, producing direct digital image, bilateral, all views
72040
Radiologic examination, spine, cervical; 2 or 3 views
72050
Radiologic examination, spine, cervical; 4 or 5 views
G0204
Diagnostic mammography, producing direct 2-d digital image, bilateral, all views
93970
Duplex scan of extremity veins including responses to compression and other maneuvers; complete bilateral study
73110
Radiologic examination, wrist; complete, minimum of 3 views
74220
Radiologic examination; esophagus
74176
Computed tomography, abdomen and pelvis; without contrast material
73721
Magnetic resonance (eg, proton) imaging, any joint of lower extremity; without contrast material
73630
Radiologic examination, foot; complete, minimum of 3 views
71275
Computed tomographic angiography, chest (noncoronary), with contrast material(s), including noncontrast images, if performed, and image postprocessing
70486
Computed tomography, maxillofacial area; without contrast material
76830
Ultrasound, transvaginal
G0206
Diagnostic mammography, producing direct 2-d digital image, unilateral, all views
77052
Computer-aided detection (computer algorithm analysis of digital image data for lesion detection) with further review for interpretation, with or without digitization of film radiographic images; screening mammography (List separately in addition to code for primary procedure)
76536
Ultrasound, soft tissues of head and neck (eg, thyroid, parathyroid, parotid), real time with image documentation
Q9967
Low osmolar contrast material, 300-399 mg/ml iodine concentration, per ml
70450
Computed tomography, head or brain; without contrast material
73564
Radiologic examination, knee; complete, 4 or more views
76770
Ultrasound, retroperitoneal (eg, renal, aorta, nodes), real time with image documentation; complete
73590
Radiologic examination; tibia and fibula, 2 views
76705
Ultrasound, abdominal, real time with image documentation; limited (eg, single organ, quadrant, follow-up)
70553
Magnetic resonance (eg, proton) imaging, brain (including brain stem); without contrast material, followed by contrast material(s) and further sequences
78452
Myocardial perfusion imaging, tomographic (SPECT) (including attenuation correction, qualitative or quantitative wall motion, ejection fraction by first pass or gated technique, additional quantification, when performed); multiple studies, at rest and/or stress (exercise or pharmacologic) and/or redistribution and/or rest reinjection
72114
Radiologic examination, spine, lumbosacral; complete, including bending views, minimum of 6 views
93880
Duplex scan of extracranial arteries; complete bilateral study
77002
Fluoroscopic guidance for needle placement (eg, biopsy, aspiration, injection, localization device)
76700
Ultrasound, abdominal, real time with image documentation; complete
72148
Magnetic resonance (eg, proton) imaging, spinal canal and contents, lumbar; without contrast material
73080
Radiologic examination, elbow; complete, minimum of 3 views
74000
Radiologic examination, abdomen; single anteroposterior view
74178
Computed tomography, abdomen and pelvis; without contrast material in one or both body regions, followed by contrast material(s) and further sections in one or both body regions
73060
Radiologic examination; humerus, minimum of 2 views
72080
Radiologic examination, spine; thoracolumbar, 2 views
73030
Radiologic examination, shoulder; complete, minimum of 2 views
72141
Magnetic resonance (eg, proton) imaging, spinal canal and contents, cervical; without contrast material
76775
Ultrasound, retroperitoneal (eg, renal, aorta, nodes), real time with image documentation; limited
72125
Computed tomography, cervical spine; without contrast material
70498
Computed tomographic angiography, neck, with contrast material(s), including noncontrast images, if performed, and image postprocessing
72110
Radiologic examination, spine, lumbosacral; minimum of 4 views
73562
Radiologic examination, knee; 3 views
73610
Radiologic examination, ankle; complete, minimum of 3 views
71260
Computed tomography, thorax; with contrast material(s)
72131
Computed tomography, lumbar spine; without contrast material
93971
Duplex scan of extremity veins including responses to compression and other maneuvers; unilateral or limited study
76870
Ultrasound, scrotum and contents
74177
Computed tomography, abdomen and pelvis; with contrast material(s)
72192
Computed tomography, pelvis; without contrast material
73560
Radiologic examination, knee; 1 or 2 views
70450
Computed tomography, head or brain; without contrast material
71250
Computed tomography, thorax; without contrast material
71101
Radiologic examination, ribs, unilateral; including posteroanterior chest, minimum of 3 views
72100
Radiologic examination, spine, lumbosacral; 2 or 3 views
71250
Computed tomography, thorax; without contrast material
71020
Radiologic examination, chest, 2 views, frontal and lateral
71100
Radiologic examination, ribs, unilateral; 2 views
71010
Radiologic examination, chest; single view, frontal
73130
Radiologic examination, hand; minimum of 3 views
73550
Radiologic examination, femur, 2 views
73520
Radiologic examination, hips, bilateral, minimum of 2 views of each hip, including anteroposterior view of pelvis
73510
Radiologic examination, hip, unilateral; complete, minimum of 2 views
73221
Magnetic resonance (eg, proton) imaging, any joint of upper extremity; without contrast material(s)
72070
Radiologic examination, spine; thoracic, 2 views

Medical Malpractice Cases

None Found

Medical Board Sanctions

None Found

Referrals

NPI
Doctor Name
Specialty
Count
1467485334
Diagnostic Radiology
5,317
1063451243
Internal Medicine
4,166
1568417889
Pulmonary Disease
3,863
1811956220
Medical Oncology
3,330
1417985276
Cardiovascular Disease (Cardiology)
3,300
1467492751
Dermatology
2,251
1215982855
Cardiovascular Disease (Cardiology)
2,165
1265468094
Diagnostic Radiology
1,910
1134153380
Internal Medicine
1,789
1396714358
Internal Medicine
1,783
*These referrals represent the top 10 that Dr. Choi has made to other doctors

Publications

Multifrequency swept common-path en-face OCT for wide-field measurement of interior surface vibrations in thick biological tissues. - Optics express
Microvibrations that occur in bio-tissues are considered to play pivotal roles in organ function; however techniques for their measurement have remained underdeveloped. To address this issue, in the present study we have developed a novel optical coherence tomography (OCT) method that utilizes multifrequency swept interferometry. The OCT volume data can be acquired by sweeping the multifrequency modes produced by combining a tunable Fabry-Perot filter and an 840 nm super-luminescent diode with a bandwidth of 160 nm. The system employing the wide-field heterodyne method does not require mechanical scanning probes, which are usually incorporated in conventional Doppler OCTs and heterodyne-type interferometers. These arrangements allow obtaining not only 3D tomographic images but also various vibration parameters such as spatial amplitude, phase, and frequency, with high temporal and transverse resolutions over a wide field. Indeed, our OCT achieved the axial resolution of ~2.5 μm when scanning the surface of a glass plate. Moreover, when examining a mechanically resonant multilayered bio-tissue in full-field configuration, we captured 22 nm vibrations of its internal surfaces at 1 kHz by reconstructing temporal phase variations. This so-called "multifrequency swept common-path en-face OCT" can be applied for measuring microdynamics of a variety of biological samples, thus contributing to the progress in life sciences research.
Profile measurement of glass sheet using multiple wavelength backpropagation interferometry. - Applied optics
Multiple-wavelength backpropagation interferometry based on a spectral interferometer is proposed for measuring thin glass sheets with nanometer accuracy. The multiwavelength backpropagation method introduced to the spectral interferometer eliminates time-encoded wavelength sweeping and mechanical scanning, which enables high-speed profile measurements. The applicability of the proposed method is experimentally demonstrated through cross-sectional profile and vibrating surface displacement measurements of a glass sheet.
Multi-gigahertz frequency comb-based interferometry using frequency-variable supercontinuum generated by optical pulse synthesizer. - Optics express
A multi-gigahertz frequency comb (MGFC)-based interferometer was developed for profilometry and tomography using a frequency variable supercontinuum (SC). The comparatively flattened and broadened SC light source with variable multi-gigahertz interval frequency was developed using an optical pulse synthesizer and highly nonlinear dispersion flattened fiber. The generated SC provided a stable interference output with a full width half maximum of 19 μm during interval frequency sweeping of over 400 MHz. We experimentally confirmed that the interference signal exhibited an envelope-only waveform without fringes, which enabled the drastic reduction of the sampling points resulting in high speed measurement. A full-field 3-D image with 320 × 256 × 300 pixels was acquired with a measurement time of only 10 seconds. It was demonstrated that the MGFC-based interferometer with the novel SC light source has the potential for application in a high speed full-field 3-D metrology.
Phase-shifting laser diode interferometer using pulse modulation. - Applied optics
A phase-shifting laser diode interferometer that uses direct pulse modulation is proposed and demonstrated. We found that a laser beam with a wide range of wavelength variation at constant optical power could be generated when a pulsed current was injected into the laser diode. We constructed a highly accurate interferometer by using a pair of interferometers. Several experiments, such as observations of temporal interference signals and spatial interferograms, measurement of a concave mirror, and duplicate measurements, confirmed the characteristics of pulse modulation and demonstrated the effectiveness of our technique.
Utilization of frequency information in a linear wavenumber-scanning interferometer for profile measurement of a thin film. - Applied optics
The positions of the front and rear surfaces of a silicon dioxide film with 4 μm thickness is measured with a novel and simple method in which both amplitude and phase of a sinusoidal wave signal corresponding to one optical path difference of a reflecting surface is utilized in a linear wavenumber-scanning interferometer. For this utilization, the scanning width and the position of the reference mirror are adjusted exactly to distinguish the two sinusoidal waves corresponding to the two surfaces of the film. The scanning width of the wavenumber and wavelength of the light source are 0.326×10(-3) nm(-1) and 140 nm, respectively.
para-Aminobenzoic acid is a precursor in coenzyme Q6 biosynthesis in Saccharomyces cerevisiae. - The Journal of biological chemistry
Coenzyme Q (ubiquinone or Q) is a crucial mitochondrial lipid required for respiratory electron transport in eukaryotes. 4-Hydroxybenozoate (4HB) is an aromatic ring precursor that forms the benzoquinone ring of Q and is used extensively to examine Q biosynthesis. However, the direct precursor compounds and enzymatic steps for synthesis of 4HB in yeast are unknown. Here we show that para-aminobenzoic acid (pABA), a well known precursor of folate, also functions as a precursor for Q biosynthesis. A hexaprenylated form of pABA (prenyl-pABA) is normally present in wild-type yeast crude lipid extracts but is absent in yeast abz1 mutants starved for pABA. A stable (13)C(6)-isotope of pABA (p- amino[aromatic-(13)C(6)]benzoic acid ([(13)C(6)]pABA)), is prenylated in either wild-type or abz1 mutant yeast to form prenyl-[(13)C(6)]pABA. We demonstrate by HPLC and mass spectrometry that yeast incubated with either [(13)C(6)]pABA or [(13)C(6)]4HB generate both (13)C(6)-demethoxy-Q (DMQ), a late stage Q biosynthetic intermediate, as well as the final product (13)C(6)-coenzyme Q. Pulse-labeling analyses show that formation of prenyl-pABA occurs within minutes and precedes the synthesis of Q. Yeast utilizing pABA as a ring precursor produce another nitrogen containing intermediate, 4-imino-DMQ(6). This intermediate is produced in small quantities in wild-type yeast cultured in standard media and in abz1 mutants supplemented with pABA. We suggest a mechanism where Schiff base-mediated deimination forms DMQ(6) quinone, thereby eliminating the nitrogen contributed by pABA. This scheme results in the convergence of the 4HB and pABA pathways in eukaryotic Q biosynthesis and has implications regarding the action of pABA-based antifolates.
Lysogens and free viruses in fresh, brackish, and marine waters: a Bayesian analysis. - FEMS microbiology ecology
A yearlong study was conducted to determine factors that affect the abundance and distribution of lysogens and free viruses at fresh-, brackish-, and saltwater stations in Newport Bay, CA. The viral and bacterial abundance were highest in the freshwater (average 1.1 x 10(8) and 1.1 x 10(7) mL(-1), respectively) and lowest in the marine water (average 0.4 x 10(8) and 0.5 x 10(7) mL(-1), respectively). Bacterial and viral counts were also several times higher during the summer than in winter. Approximately, 35% of the 141 samples were inducible in the presence of mitomycin C. The highest percentage of inducible lysogens was observed in marine waters (42%), while the lowest percentage was observed in the warmer freshwater (23%). A statistical model for the joint occurrence of lysogens and free viruses was formulated and estimated using Bayesian techniques to understand the key environmental determinants of viruses and lysogens. Our results support the existence of significant heterogeneity between the saltwater and freshwater sites. A parsimonious model that combines the two saltwater sites performs best among the specifications that were considered. Bacteria and water temperature were significant determinants of virus counts, whereas lysogen relationships are unclear. Importantly, conditional on the covariates, viruses and lysogen fractions exhibit robust negative correlation.
Microbial source tracking in a small southern California urban watershed indicates wild animals and growth as the source of fecal bacteria. - Applied microbiology and biotechnology
Three independent microbial source tracking (MST) methods were applied to a small urban subwatershed in Orange County, California. Fifty-seven water samples collected over summer 2002 were analyzed for human adenovirus and enterovirus. Enterococci and E. coli were isolated for antibiotic resistance analysis (ARA) and for PCR identification of human- and animal-specific toxin genes, respectively. All water samples were PCR negative for human enteroviruses and E. coli human-specific toxin gene. E. coli toxin markers revealed the presence of toxin genes specific to bird, rabbit, and cow. Enterococci ARA results supported this conclusion and indicated that fecal bacteria from bird and wild animal feces as well as soil were the predominant source found in the watershed. An E. coli, isolated from the watershed and inoculated back into the heat-sterilized storm drain water, increased 4 log units within 6 days. Collectively, these results suggest that bird and wild animal feces, soil amendments, and/or fecal coliform growth in the storm drain are the major contributors to the fecal bacterial pollution in downstream areas. However, human adenoviruses were detected on two occasions. Fecal bacterial concentrations were not elevated on these two occasions, suggesting that the elevated levels of fecal indicator bacteria in this small watershed could be unrelated to the source of human adenovirus.
Frequency-comb-based interferometer for profilometry and tomography. - Optics letters
A novel interferometry technique using a frequency-comb light source is proposed for surface profilometry and tomography of discontinuous objects. Surface profile measurement is performed by sweeping the comb interval frequency without mechanical scanning. Step heights of 0.5 and 1.0 mm are successfully measured by use of the scheme with 9 mum accuracy.
Real-time PCR quantification of human adenoviruses in urban rivers indicates genome prevalence but low infectivity. - Applied and environmental microbiology
Real-time PCR was applied to quantify the abundance of human adenoviruses in two southern California urban rivers, the San Gabriel and Los Angeles. A total of 114 river samples from five different locations were collected over a 1-year period and analyzed for human adenoviruses, along with fecal indicator bacteria and coliphages. Adenoviruses were detected by real-time PCR in approximately 16% of the samples, with concentrations ranging from 10(2) to 10(4) genomes per liter. However, a plaque assay using two human tissue culture cell lines, HEK-293A and A549, yielded negative results, suggesting that adenoviruses detected by real-time PCR are likely noninfectious. Enterovirus genome was detected in approximately 7% of the samples by reverse transcription-PCR. Analysis by Spearman's rho rank order correlation showed significant correlations between fecal indicator bacteria and indicator virus (total coliform, fecal coliform, enterococcus, and coliphage values). However, no significant correlations were found between human adenoviruses quantified by real-time PCR and culturable coliphages or fecal indicator bacteria. Kruskal-Wallis chi-square analysis showed significant seasonal variability of all fecal indicator bacteria and coliphages, while no significant variability was observed for adenoviruses or enteroviruses. This study presents the first quantitative measurement of human adenovirus genomes in urban rivers and their statistical relationship to fecal indicator bacteria and coliphages. The uncoupling between high-number genome copies of adenoviruses detected by real-time PCR and the absence of infectivity detected by tissue culture suggests that genome-based detection methods are inadequate for direct assessment of human health risk.

Map & Directions

3901 Lone Tree Way Antioch, CA 94509
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