Biomedical subjects

M C Huang

Publications and source records attributed to M C Huang.

At least 37 records · Page 2Linked to original sources

PubMed2000

High-precision isotope ratio mass spectrometry and stable isotope precursors for tracer studies in cell culture.

The use of stable isotope-labeled tracers is demonstrated in an in vitro system with analysis by high-precision isotope ratio mass spectrometry (IRMS), using n-3 long-chain polyunsaturated fatty acid (LCP) biosynthesis from [U-(13)C]18:3n-3 (18:3n-3*) in Y79 human retinoblastoma cells as a model system. The cells were cultured as a suspension in RPMI 1640 medium supplemented with 15% fetal calf serum at 37 degrees C with 5% CO(2) in air. They were harvested by sedimentation and cell lipids were extracted to determine the presence of 18:3n-3* metabolites using gas chromatography-combustion (GCC)-IRMS. As the dose of 18:3n-3* was systematically increased from treatment to treatment, the atom percent excess and the amounts of biosynthesized LCP* increased, while the percentage dose in each n-3 LCP* remained constant. Cultures incubated with 0.5 micromol (10 microM) of albumin-bound 18:3n-3, composed of 18:3n-3* diluted 1/60 or 1/100 with natural abundance 18:3n-3, yielded products with enrichments about 1.5 at.% excess (delta(13)C(PDB) < 1500 per thousand), which is optimal for high-precision measurements. Kinetics in Y79 cells incubated with 18:3n-3* showed that n-3 LCP* incorporation increased over time; 18:3n-3*, 20:5n-3*, 22:5n-3*, and 22:6n-3* were detected at all time points with the 1/60 dilution. These data document experimental parameters for optimal stable isotope use and IRMS detection for in vitro tracer methodology.

Carbon Isotopes↗

PubMed2000

P-selectin glycoprotein ligand-1 and E-selectin ligand-1 are differentially modified by fucosyltransferases Fuc-TIV and Fuc-TVII in mouse neutrophils.

P-selectin glycoprotein ligand-1 (PSGL-1) and E-selectin ligand-1 (ESL-1) are the two major selectin ligands on mouse neutrophils. Transfection experiments demonstrate that each ligand requires alpha1,3-fucosylation for selectin-binding. However, the relative contributions made by the two known myeloid alpha1, 3-fucosyltransferases Fuc-TVII or Fuc-TIV to this alpha1, 3-fucosylation are not yet clear. To address this issue, we have used mice deficient in Fuc-TIV and/or Fuc-TVII to examine how these enzymes generate selectin-binding glycoforms of PSGL-1 and ESL-1 in mouse neutrophils. Selectin binding was analyzed by affinity isolation experiments using recombinant, antibody-like forms of the respective endothelial selectins. We observe essentially normal binding of E- or P-selectin to PSGL-1 expressed by Fuc-TIV-deficient neutrophils but find that PSGL-1 expressed by Fuc-TVII-deficient neutrophils is not bound by E- or P-selectin. By contrast, E-selectin binds with normal efficiency to ESL-1 on Fuc-TVII-deficient neutrophils but exhibits an 80% reduction in its ability to bind ESL-1 isolated from Fuc-TIV-deficient neutrophils. The same specificity with which Fuc-TVII and Fuc-TIV generate selectin-binding forms of PSGL-1 and ESL-1 was found in transfection experiments with CHO-Pro(-)5 cells. In contrast, each fucosyltransferase alone could generate selectin-binding glycoforms of each of the two ligands in CHO-DUKX-B1 cells. Our data imply that in mouse neutrophils and their precursors, Fuc-TVII exclusively directs expression of PSGL-1 glycoforms bound with high affinity by P-selectin. By contrast, Fuc-TIV preferentially directs expression of ESL-1 glycoforms that exhibit high affinity for E-selectin. This substrate specificity can be mimicked in CHO-Pro(-)5 cells.

Animals↗

PubMed2000

Linkage of familial amyotrophic lateral sclerosis with frontotemporal dementia to chromosome 9q21-q22.

CONTEXT: Occasionally, 2 or more major neurodegenerative diseases arise simultaneously. An understanding of the genetic bases of combined disorders, such as amyotrophic lateral sclerosis (ALS) with frontotemporal dementia (FTD), will likely provide insight into mechanisms of these and related neurodegenerative diseases. OBJECTIVE: To identify loci that contain genes whose defects cause ALS. DESIGN: A genome-wide linkage analysis of 2 data sets from an ongoing study begun in the mid-1980s at 4 university research centers. SUBJECTS: An initial subset of 16 families (549 people) potentially informative for genetic analysis, in which 2 or more individuals were diagnosed as having ALS, identified from a Boston data set of 400 families and 4 families potentially informative (244 people) subsequently identified from a Chicago data set of more than 300 families to test a hypothesis based on findings from the Boston families. MAIN OUTCOME MEASURES: Linkage calculations assuming autosomal dominant inheritance with age-dependent penetrance (a parametric logarithm-of-odds [lod] score of 1.0 or greater required for further study of a potential locus); crossover analysis involving the ALS-FTD locus. RESULTS: In a set of families in which persons develop both ALS and FTD or either ALS or FTD alone, a genetic locus that is linked to ALS with FTD located between markers D9S301 and D9S167 was identified on human chromosome 9q21-q22. Families with ALS alone did not show linkage to this locus. Crossover analysis indicates this region covers approximately 17 cM. CONCLUSION: These data suggest that a defective gene located in the chromosome 9q21-q22 region may be linked to ALS with FTD. JAMA. 2000;284:1664-1669.

Aged↗

PubMed2000

N-218 MLN64, a protein with StAR-like steroidogenic activity, is folded and cleaved similarly to StAR.

The steroidogenic acute regulatory protein (StAR) facilitates the movement of cholesterol from the outer to inner mitochondrial membrane in adrenal and gonadal cells, fostering steroid biosynthesis. MLN64 is a 445-amino acid protein of unknown function. When 218 amino-terminal residues of MLN-64 are deleted, the resulting N-218 MLN64 has 37% amino acid identity with StAR and 50% of StAR's steroidogenic activity in transfected cells. Antiserum to StAR cross-reacts with N-218 MLN64, indicating the presence of similar epitopes in both proteins. Western blotting shows that MLN64 is proteolytically cleaved in the placenta to a size indistinguishable from N-218 MLN64. Bacterially expressed N-218 MLN64 exerts StAR-like activity to promote the transfer of cholesterol from the outer to inner mitochondrial membrane in vitro. CD spectroscopy indicates that N-218 MLN64 is largely alpha-helical and minimally affected by changes in ionic strength or the hydrophobic character of the solvent, although glycerol increases the beta-sheet content. However, decreasing pH diminishes structure, causing aggregation. Limited proteolysis at pH 8.0 shows that the C-terminal domain of N-218 MLN64 is accessible to proteolysis whereas the 244-414 domain is resistant, suggesting it is more compactly folded. The presence of a protease-resistant domain and a protease-sensitive carboxy-terminal domain in N-218 MLN64 is similar to the organization of StAR. However, as MLN64 never enters the mitochondria, the protease-resistant domain of MLN64 cannot be a mitochondrial pause-transfer sequence, as has been proposed for StAR. Thus the protease-resistant domain of N-218 MLN64, and by inference the corresponding domain of StAR, may have direct roles in their action to foster the flux of cholesterol from the outer to the inner mitochondrial membrane.

Amino Acid Sequence↗

PubMed2000

The alpha-fetoprotein promoter is the target of Afr1-mediated postnatal repression.

The alpha-fetoprotein (AFP) gene is transcribed at high levels in the fetal liver and is repressed at birth, leading to low but detectable levels of AFP mRNA in the adult liver. This repression is regulated, in part, by a locus that is unlinked to AFP called Alpha-fetoprotein regulator 1 (Afr1). Previous studies showed that Afr1 regulation is independent of the AFP enhancers but requires the 1-kb AFP promoter/repressor region. Here, we demonstrate that a transgene with the 250-bp AFP promoter region linked to AFP enhancer element EII is expressed in the fetal liver and is postnatally repressed. In addition, this transgene is regulated by Afr1. These data indicate that the promoter is involved in postnatal AFP repression. Furthermore, we provide a high-resolution map of the Afr1 locus on mouse chromosome 15.

Animals↗

PubMed2000

Differentiation of obstructive from non-obstructive small bowel dilatation on CT.

PURPOSE: to find a useful decision procedure for the differentiation of obstructive from non-obstructive small bowel (SB) dilatation on the computed tomography (CT). MATERIALS AND METHODS: four criteria were divided into different degrees and evaluated. These include: (A): continuity (non-continuous, continuous); (B): transition zone (absent, gradual, abrupt); (C): prestenotic SB fluid (minimal, about one-fourth, one-half, and three-fourths, nearly complete); and (D): colonic contents (minimal, moderate, considerable). One hundred fifty-three examinations, 86 obstructive and 67 non-obstructive, were analyzed using chi(2)-square tests to determine the relationship of each criterion to the presence of small bowel obstruction (SBO), whether the proportions of various degrees of these criteria differed significantly among the obstructive and non-obstructive subgroups, and to classify the criteria with a tree-based model (calculated by the computer) for the development of a useful decision procedure. RESULTS: in each of the four criteria, the trend of probability of obstruction was statistically significant (P=0.0000). The proportions of most, except two, of the various degrees of different criteria in the obstructive and non-obstructive subgroups differed significantly (P<0.01). The obstruction tends to have a continuou dilatation, an abrupt transition, more prestenotic SB fluids, and less colonic contents. The results of classification by a tree-based model were 76 true-positive, ten false-negative, six false-positive, and 61 true-negative. The sensitivity was 88%; specificity was 91%; positive predictive value was 93%; negative predictive value was 86%; and the overall accuracy was 90%. CONCLUSION: by analyzing the above four criteria together, a useful tree-based model can be developed and utilized as a supplemental decision procedure for the differentiation of obstructive from non-obstructive SB dilatation. The accuracy can be further promoted if the factor of a recognized pathologic condition is taken into consideration.

Decision Trees↗

PubMed2000

Male-specific band in random amplified microsatellite polymorphism fingerprints of Holstein cattle.

A total of 65 blood samples collected from Holstein cattle were employed for DNA extraction. Genomic DNA were amplified by means of random amplified polymorphic DNA (RAPD). One hundred and one random primers (Operon kits OPAA, OPAO, OPAV, OPC, OPE and OPA-06) were used for polymerase chain reactions (PCR). The PCR products were size fractionated by means of electrophoresis in agarose gel, transferred to a nylon membrane, and then hybridized with a alpha-32P-labeled microsatellite probe for random amplified microsatellite polymorphism (RAMPO) analysis. All the primers produced many amplification patterns in RAMPO fingerprints, but only OPE-01 (5'-CCCAAGGTCC-3') yielded a male-specific strong signal. Among the 65 cases, the specific band could be observed in the RAMPO fingerprints of the 24 male samples but not in the 41 female samples. Therefore, this specific band is peculiar to male cattle.

Animals↗

PubMed2000

The value of angiography in diagnosis of Meckel's diverticulum: case report.

Meckel's diverticulum is the most common anomaly of the gastrointestinal tract and usually produces no symptoms, although the classic symptom is painless rectal bleeding in a child. Because most symptomatic diverticula in children contain ectopic gastric tissue, radionuclide imaging using a technetium 99m pertechnetate scan is considered to be the method of choice. However, a bleeding Meckel's diverticulum may not be detected by pertechnetate imaging despite the presence of ectopic gastric mucosa. When the scan is negative, visceral angiography is an alternative procedure for detecting Meckel's diverticulum. We encountered a case of pathology-proven Meckel's diverticulum whose angiography result was diagnostic, while upper gastrointestinal panendoscopy, colonofibroscopy, barium enema studies, and repeated radionuclide scans were all negative. We report on this case to emphasize the potential role for angiographic detection of Meckel's diverticulum.

Angiography↗

PubMed1999

Complete nucleotide sequence of pig (Sus scrofa) mitochondrial genome and dating evolutionary divergence within Artiodactyla.

The complete nucleotide sequence of the pig (Sus scrofa) mitochondrial genome, containing 16613bp, is presented in this report. The genome is not a specific length because of the presence of the variable numbers of tandem repeats, 5'-CGTGCGTACA in the displacement loop (D-loop). Genes responsible for 12S and 16S rRNAs, 22 tRNAs, and 13 protein-coding regions are found. The genome carries very few intergenic nucleotides with several instances of overlap between protein-coding or tRNA genes, except in the D-loop region. For evaluating the possible evolutionary relationships between Artiodactyla and Cetacea, the nucleotide substitutions and amino acid sequences of 13 protein-coding genes were aligned by pairwise comparisons of the pig, cow, and fin whale. By comparing these sequences, we suggest that there is a closer relationship between the pig and cow than that between either of these species and fin whale. In addition, the accumulation of transversions and gaps in pig 12S and 16S rRNA genes was compared with that in other eutherian species, including cow, fin whale, human, horse, and harbor seal. The results also reveal a close phylogenetic relationship between pig and cow, as compared to fin whale and others. Thus, according to the sequence differences of mitochondrial rRNA genes in eutherian species, the evolutionary separation of pig and cow occurred about 53-60 million years ago.

Amino Acids↗

PubMed1999

Genotoxic effects of triphenyltin acetate and triphenyltin hydroxide on mammalian cells in vitro and in vivo.

Two organotin pesticides, triphenyltin acetate (TPTA) and triphenyltin hydroxide (TPTH), were evaluated for their ability to induce micronuclei (MN) and sister chromatid exchange (SCE) in vitro using cultured Chinese hamster ovary (CHO) cells and in vivo BALB/c mouse erythrocytes. Both pesticides induced a dose-dependent increase but only TPTH induced a significant increase in MN at the highest dose (150 ng/ml) tested in CHO cells. With adding S9 microsomal fractions, both pesticides induced a meaningful MN induction at 150 ng/ml and a dose-dependent significant increase in SCE. In vivo MN induction in erythrocytes was conducted by treating BALB/c mice orally or intraperitoneally with these pesticides either in a single or triple treatments. Oral gavage (p.o.) of TPTA resulted in a dose-related significant increase of MN induction in peripheral blood and of TPTH induced a significant increase in micronucleated reticulocyte (MNRETs) only in a single treatment. Intraperitoneal administration of TPTA or TPTH, however, resulted in meaningless random increases in MN though these increases might be attributable to toxic effects. The MNRETs levels in the treatment with both pesticides were independent to the sampling time. This study demonstrated that TPTA and TPTH was potential chromosome mutagens.

Animals↗

PubMed1999

Intermediate-term clinical experience with the Ahmed Glaucoma Valve implant.

PURPOSE: We studied the intermediate-term clinical experience with the Ahmed Glaucoma Valve implant (New World Medical, Inc, Rancho Cucamonga, California). METHODS: In this multicenter, retrospective case series, we studied 159 eyes (144 patients) treated with the Ahmed Glaucoma Valve with a mean +/- SEM (standard error of mean) follow-up of 13.4 +/- 0.7 months (range, 4 to 44 months). The mean +/- SEM age was 60.9 +/- 1.9 years (range, 0.1 to 103 years). Surgical success was defined as intraocular pressure less than 22 mm Hg and greater than 5 mm Hg without additional glaucoma surgery and without loss of light perception. Postoperative use of antiglaucoma medications was not a criterion for success or failure. The definition of hypotony was intraocular pressure of 5 mm Hg or less in two consecutive visits. RESULTS: Intraocular pressure was reduced from a mean of 32.7 +/- 0.8 mm Hg before surgery to 15.9 +/- 0.6 mm Hg (P < .0001) at the most recent follow-up after surgery. The number of antiglaucoma medications was decreased from 2.7 +/- 0.1 before surgery to 1.1 +/- 0.1 after surgery (P < .0001). The cumulative probability of success was 87% at 1 year and 75% at 2 years after surgery (Kaplan-Meier life-table analysis). Postoperatively, 24 (15%) of 159 eyes had intraocular pressure greater than or equal to 22 mm Hg. The visual acuity was improved or within one Snellen line in 131 eyes (82%). Complications occurred in 75 eyes (47%), the majority of which did not affect surgical outcome. The most common complication was obstruction of the tube, which was observed in 17 eyes (11%). Transient postoperative hypotony was found in 13 eyes (8%). CONCLUSIONS: The Ahmed Glaucoma Valve implant is effective in lowering intraocular pressure, and postoperative hypotony is not commonly associated with this implant.

Adolescent↗

PubMed1999

Percolation thresholds, critical exponents, and scaling functions on planar random lattices and their duals.

The bond-percolation process is studied on periodic planar random lattices and their duals. The thresholds and critical exponents of the percolation transition are determined. The scaling functions of the percolating probability, the existence probability of the appearance of percolating clusters, and the mean cluster size are also calculated. The simulation result of the percolation threshold is p(c)=0.3333+/-0.0001 for planar random lattices, and 0.6670+/-0.0001 for the duals of planar random lattices. We conjecture that the exact value of p(c) is 1/3 for a planar random lattice and 2/3 for the dual of a planar random lattice. By taking possible errors into account, the results of our critical exponents agree with the values given by the universality hypothesis. By properly adjusting the metric factors on random lattices and their duals, we demonstrate explicitly that the idea of a universal scaling function with nonuniversal metric factors in the finite-size scaling theory can be extended to random lattices and their duals for the existence probability, the percolating probability, and the mean cluster size.

Journal Article↗

PubMed1999

Risk factors for a first febrile convulsion in children: a population study in southern Taiwan.

PURPOSE: To identify risk factors for a first febrile convulsion among 3-year-old children by a matched case-control population study. METHODS: All 11,714 neonatal survivors born in Tainan City between October 1989 and September 1991 were enrolled. At age 3, 10,460 children were available for telephone survey for febrile convulsions, and were confirmed by home visit interviews. Those without history of seizure were randomly matched to each febrile convulsion case by age, gender, and residence district. RESULTS: Two hundred fifty six children had febrile convulsions, and 218 of them and their matched controls were available for analysis. The febrile convulsion cases had significantly more febrile episodes (four or more) per year (33.0 vs. 22.5%; p = 0.021), and cases had a higher percentage of developmental delay (3.7 vs. 0.4%; p = 0.046) and a higher percentage of febrile convulsions in their siblings (12 vs. 0.4%; p = 0.011) than controls. The other sociodemographic, environmental, and biologic variables showed no differences between cases and controls. Step-wise logistic regression showed a highly significant independent association between febrile convulsions and history of febrile convulsions in the siblings, and a moderate one between febrile convulsions and the number of febrile episodes per year. CONCLUSIONS: The presence of febrile convulsions in the siblings and the number of fever episodes per year were the independent and significant predictors of febrile convulsion for an individual case in our population-based sample.

Case-Control Studies↗

PubMed1999

An octaene fatty acid, 4,7,10,13,16,19,22,25-octacosaoctaenoic acid (28:8n-3), found in marine oils.

We report structure determination of an octaene fatty acid, 4,7,10, 13,16,19,22,25-octacosaoctaenoic acid (28:8n-3). The molecular weight and double bond locations were determined using acetonitrile chemical ionization mass spectrometry (MS) and MS/MS and were confirmed by MS of hydrogenated and deuterogenated 28:8 and by argentation thin-layer chromatography. 28:8n-3 was 1.2 +/- 0.1%, in oil derived from the heterotrophic dinoflagellate Crypthecodinium cohnii and a commercial polyunsaturated fatty acid concentrate derived from fish oils (0.16 +/- 0.01%), both components of human dietary supplements. It was not found in whole bovine retina, cultured Y79 human retinoblastoma cells, or neonate baboon cerebral cortex. The long chain polyunsaturates present in the C. cohnii oil suggest a possible route for 28:8n-3 biosynthesis similar to that for biosynthesis of 22:6n-3.

Animals↗

PubMed1999

Detection of mammosomatotrophs in paraffin-embedded specimens of various pituitary adenomas.

BACKGROUND: There are various classification systems for pituitary adenomas based on whether mammosomatotroph cells, which simultaneously express both prolactin (PRL) and growth hormone (GH), can be found. Until the present, the identification of such cells required special techniques and could not be performed in paraffin-embedded specimens. This hindered large-scale studies for detection of mammosomatotrophs in various pituitary adenomas and, as a result, such classification has remained controversial. To establish a methodology for the detection of mammosomatotrophs in paraffin-embedded specimens and to propose a more logical classification for pituitary adenomas, the authors conducted this retrospective study. METHODS: We performed double immunofluorescence staining of PRL and GH in paraffin-embedded specimens of various pituitary adenomas with subsequent observation with a confocal laser-scanning microscope. RESULTS: Mammosomatotrophs were found in four of the 10 GH-secreting adenomas and one of the 10 clinically nonfunctioning adenomas. However, mammosomatotrophs were not identified in all 10 cases of prolactinoma. CONCLUSIONS: This is the first report in the literature that successfully demonstrates the presence of mammosomatotrophs in routine paraffin-embedded pituitary adenomas. The new methodology is important for future study of the function and role of these cells. A large-scale study for mammosomatotrophs in various pituitary adenomas with this method and a more logical classification of pituitary adenomas are proposed.

Adenoma↗

PubMed1998

Multiple isoforms of metallothionein are expressed in the porcine liver.

Isogenes are highly homologous to each other and are often difficult to ascertain, as has been the case with metallothionein, a metal-binding protein rich in cysteines. Conventional separation of metallothionein isoforms relied on ion exchange chromatography of the proteins, or screening for the sequences from gene libraries. In this study, a combination of RT-PCR and partial protein sequencing is used in the identification of metallothionein isogenes expressed in porcine liver. By this approach, we have identified expressed coding sequences which constitute 10 new isogenes. Of the four known groups of metallothioneins (MT), phylogenetic analyses place these pig isogenes in the MT-1 group, except two which are identified as being closely related to MT-2, and none in groups 3 and 4. The isogenes are thus namedpMT-1a to -1g, andpMT-2a and -2b. While each of the isogene sequences is unique, two isogenes,pMT-1e1 andpMT-1e2, share an identical amino acid sequence, differing only in specific codons. Two others,pMT-1b andpMT-1g, have a cysteine substituted by arginine, the first such sequence ever detected in MT.pMT-2a andpMT-2b are closely aligned with the MT-2 group of vertebrates, in spite of the absence of a characteristic acidic amino acid at position 10 or 11, common in other mammalian metallothioneins.

Amino Acid Sequence↗

PubMed1998

Effects of an educational program on parents with febrile convulsive children.

The purpose of this study was to characterize the effects of an educational program on knowledge, attitude, concern, and first-aid measures among parents with febrile convulsive children. All parents completed a pretest questionnaire 3 weeks before the meeting. The parents were assigned randomly into experimental (n = 65) and control (n = 64) groups on the day they attended the program. The control group completed the identical questionnaire (posttest) before the program, whereas the experimental group completed the same posttest after the program. In pretest, most parents considered electroencephalogram or computed tomography necessary in evaluating their children, suggested that immunization be postponed, and rated the risk of subsequent epilepsy as high for their children. Most of them favored frequent body temperature measurement, were very anxious about further febrile convulsion episodes during the night, and were fever phobic. After education, although only a slight change in fever anxiety was found, the experimental group showed significant improvement in knowledge, attitude, concerns, and anticipatory practice of febrile convulsion compared with the control group. In conclusion the parents' poor knowledge, negative attitudes, anxiety, and inadequate first-aid measures toward febrile convulsion can be effectively improved by an educational intervention program.

Analysis of Variance↗

PubMed1998

Feasibility study of the spectroscopic measurement of oxyhemoglobin using whole blood without pre-treatment.

A feasibility study was carried out to evaluate a chemometrics-enhanced measurement of oxyhemoglobin concentration in whole blood without pre-treatment by lysing cellular components in the sample. Conventional in vitro multi-wavelength CO oximeters pre-process blood by sonication or detergent dilution to lyse blood cells to reduce light scattering. Two limitations result: (1) residual cell membrane fragments can seed surface biofouling and (2) dilution errors can occur. A full wavelength method using multivariate analysis in chemometrics was applied to correct the light scattering effect in the measurement of oxyhemoglobin concentration. Whole blood specimens were adjusted to different oxyhemoglobin concentrations with gas mixtures (N2, CO2 and O2). An Ocean Optics miniaturized spectrophotometer with a 100 microns pathlength optical cell was used for transmission measurements from 500 to 700 nm. Original spectra were smoothed and a second derivative transformation was performed to eliminate the baseline shift and slope changes from light scattering. Indirect calibration was applied to the second derivative spectra. Two-factor cross-validation by principle components regression on two sets of data showed r2 = 0.985 and 0.946 between predicted oxyhemoglobin concentration and those measured by an AVL 912 CO oximeter with RSD = 3.85 and 6.83%, respectively. Error analysis gave s = 2.36 x 10(-5) (RSD = 0.23%) on derivative absorbance for the spectrophotometer measurement alone. Specimen settling and specimen sampling gave imprecision on derivative absorbance of s = 6.17 x 10(-4) (RSD = 4.4%) and s = 4.52 x 10(-4) (RSD = 1.4%), respectively.

Feasibility Studies↗