Biomedical subjects

Jun Chen

Publications and source records attributed to Jun Chen.

At least 235 records · Page 13Linked to original sources

PubMed2004

A unique pattern of up- and down-regulation of chemokine receptor CXCR3 on inflammation-inducing Th1 cells.

Chemokine receptor CXCR3 and its CXC ligands play major roles in Th1 cell-induced inflammatory processes. Here, we examined the expression of CXCR3 by TCR-transgenic Th1 lymphocytes that induce ocular inflammation in mice expressing the target antigen in their lenses. The essential role of CXCR3 in this model was indicated by the observation that the ocular inflammation was significantly blocked by an antibody against this receptor. CXCR3 expression by Th1 cells was elevated during their initial activation in culture and further increased during the consecutive incubation with IL-2. However, CXCR3 expression declined dramatically during the ensuing antigenic reactivation, in parallel with down-regulation of its mRNA. Yet, reactivated Th1 cells exhibited the highest degree of pathogenicity when adoptively transferred into recipients. Transferred reactivated Th1 cells proliferated vigorously and re-expressed CXCR3 while residing in the spleen of recipient mice, reaching approximately 85% positivity 4 days post cell transfer when their massive migration to the target eyes began. Importantly, infiltrating Th1 cells underwent profound phenotypic changes in the eye that closely resembled those seen during reactivation of Th1 cells in vitro and included down-regulation of CXCR3. These observations thus show that expression of CXCR3, a major participant in Th1-induced inflammation, fluctuates profoundly during cell activation and migration and is down-regulated upon re-exposure of these cells to the antigen, in vitro or in the target organ.

Adoptive Transfer↗

PubMed2004

Volumetric MRI analysis of the amygdala and hippocampus in subjects with major depression.

In order to explore the MRI volume of the amygdala and hippocampus in patients with major depression, quantitative MRI of the amygdala and hippocampus were studied in 22 patients with major depression and compared with 13 age-matched controls. The results showed that both groups exhibited similar significant hippocampal asymmetry (left smaller than right). The volume of the bilateral hippocampus was significantly smaller in the major depression group than that in control group. The patients had significant asymmetry of the amygdalar volumes (right smaller than left). No correlation was found between hippocampal volume abnormalities and ill duration. It was concluded that the hippocampus and amygdala within limbic-cortical networks may play a crucial role in the pathogenesis of major depression.

Adult↗

PubMed2004

Establishment of green fluorescent protein-expressing hepatocellular carcinoma cell lines with different metastatic potential: relevant models for in vivo monitoring of metastasis and angiogenesis.

PURPOSE: To establish stable green fluorescent protein (GFP)-expressing metastatic human hepatocellular carcinoma (HCC) cell lines with different metastatic potential for long-term in vivo studies of metastasis and angiogenesis. METHODS: The pIRES2-EGFP vector, which contains an enhanced GFP gene, was transfected into MHCC97-H and MHCC97-L, HCC cell lines with different metastatic potential. The stability of GFP expression, basic biological characteristics, invasion abilities in vitro, and spontaneous metastasis in vivo of the new cell lines (MHCC97-HG and MHCC97-LG) were studied. Microvessel density (MVD) of orthotopic implanted tumors was compared by anti-CD31 immunohistochemical staining, and real-time angiogenesis and metastasis of GFP-transfected tumors were detected by intravital fluorescent microscope. RESULTS: The GFP-transfected cell lines stably expressed green fluorescence in the absence of G418 over a 36-day period. Compared with the parental cell lines, they exhibited no distinct differences in biological characteristics. MHCC97-HG showed more aggressive invasion and spontaneous metastatic behavior than MHCC97-LG, and even its parental cell line, MHCC97-H (P<0.01). MVD levels induced by MHCC97-HG orthotopic implanted tumors were significantly higher than MHCC97-LG (P<0.01). Real-time angiogenesis and sequential steps of metastasis could be detected clearly under intravital fluorescent microscope. CONCLUSIONS: These two stable GFP-expressing HCC cell lines with the same genetic background and different metastatic potential were established, which could be useful models for monitoring metastasis and angiogenesis of HCC.

Animals↗

PubMed2004

Effects of topography and composition of titanium surface oxides on osteoblast responses.

To investigate the roles of composition and characteristics of titanium surface oxides in cellular behaviour of osteoblasts, the surface oxides of titanium were modified in composition and topography by anodic oxidation in two kinds of electrolytes, (a) 0.2 M H(3)PO(4), and (b) 0.03 M calcium glycerophosphate (Ca-GP) and 0.15 M calcium acetate (CA), respectively. Phosphorus (P: ca.10at%) or both calcium (Ca: 1-6at%) and phosphorus (P: 3-6at%) were incorporated into the anodized surfaces in the form of phosphate and calcium phosphate. Surface roughness was slightly decreased or enhanced (R(a) in the range of 0.1-0.5 microm) on the anodized surfaces. The geometry of the micro-pores in the anodized surfaces varied with diameters up to 0.5 microm in 0.2 M H(3)PO(4) and to 2 microm in 0.03 M Ca-GP and 0.15 M CA, depending on voltages and electrolyte. Contact angles of all the anodic oxides were in the range of 60-90 degrees. Cell culture experiments demonstrated absence of cytotoxicity and an increase of osteoblast adhesion and proliferation by the anodic oxides. Cells on the surfaces with micro-pores showed an irregular and polygonal growth and more lamellipodia, while osteoblasts on the titanium surface used as a control or on anodic oxides formed at low voltages showed many thick stress fibres and intense focal contacts. Alkaline phosphatase (ALP) activity of the cells did not show any correlation with surface characteristics of anodic oxides.

Biocompatible Materials↗

PubMed2004

Static compression induces zonal-specific changes in gene expression for extracellular matrix and cytoskeletal proteins in intervertebral disc cells in vitro.

Compressive stimuli associated with weight-bearing and loading of the intervertebral disc are believed to be important regulators of disc cell metabolism. In this study, changes in gene expression levels for extracellular matrix and cytoskeletal proteins were quantified in disc cells in an alginate culture system subjected to static unconfined compression (25% compressive strain) after different time periods (2, 18 and 30 h). Differences in gene expression were observed between anulus fibrosus and nucleus pulposus cells following static compression for the matrix proteins studied here. Anulus fibrosus cells responded to mechanical deformation at the 30-h time point, with increasing gene expression for types I and II collagen, aggrecan, biglycan, decorin and lumican. In contrast, nucleus pulposus cells were not responsive to mechanical loading with changes in gene expression for these matrix proteins at any time. Our results also show that anulus fibrosus cells, but not nucleus pulposus cells, responded to static compression with increased expression of vimentin mRNA as well as increased polymerization of vimentin subunits. The results of the current study illustrate that fibrochondrocytes of the anulus fibrosus may regulate biosynthesis at the transcriptional level following mechanical deformation in an alginate construct. In contrast, the biological response of nucleus pulposus cells to these same stimuli is not detectable. These differences may be attributed to the presence of a notochordal cell population in the immature nucleus pulposus studied here, with a more diffuse and stiff cytoskeleton that may restrict deformations or shape changes upon compressive loading.

Animals↗

PubMed2004

Bimodal induction of dopamine-mediated striatal neurotoxicity is mediated through both activation of D1 dopamine receptors and autoxidation.

Striatal neurodegeneration occurs through unknown mechanisms in certain neurodegenerative disorders characterized by increased and sustained synaptic levels of dopamine (DA). Treatment of rat primary striatal neurons with DA causes profound neurotoxicity, with increased production of free radicals and accelerated neuronal death. DA effects were partly reduced by the antioxidant sodium metabisulfite (SMBS), and the D1 DA receptor antagonist, SCH 23390, and were completely blocked upon co-treatment with SMBS and SCH 23390. Part of DA effects were mimicked by either H(2)O(2), or by the D1 agonist, SKF R-38393, indicating the existence of two distinct signaling pathways through which the neurotoxicity of DA is manifest. DA effects did not proceed through D2-like DA or beta-adrenergic receptor signaling pathways. The D1 receptor-mediated and the autoxidative pathways of DA neurotoxicity converge to cause activation and/or increased synthesis of neuronal and inducible, but not endothelial, nitric oxide synthase (NOS). The reduction of DA striatal neurotoxicity through blockade of D1 DA receptors, suggests novel therapeutic approaches in the management of striatal neurodegeneration.

Animals↗

PubMed2004

Tissue-specific effect of estradiol on endothelial cell-dependent lymphocyte recruitment.

Estrogen profoundly affects onset and severity of many immune-mediated diseases. In our murine model of drug-induced autoimmunity, female-specific, estrogen-dependent increase in splenic lymphocyte homing was directly implicated in increased disease severity. The present study evaluated the effect of estradiol on microvascular endothelial cells from the spleen compared to endothelial cells from the dermis, which has no disease manifestation in this model. Estradiol increased spleen endothelial cell estrogen receptor (ER) alpha 2.9-fold and decreased estrogen receptor beta 2.1-fold while decreasing both receptors on dermal cells. Estradiol enhanced adhesion of D10 cells to spleen but not dermal endothelial cells 1.53-fold (P < 0.001), an increase that was inhibited by antibodies to VCAM-1 and ICAM-1, and by the estrogen receptor antagonists tamoxifen and ICI 182,780. Estradiol induced greater VCAM-1 expression on spleen than dermal endothelial cells (P < 0.05). Estradiol increased spleen endothelial cell estrogen receptor alpha 2.9-fold and decreased estrogen receptor beta 2.1-fold while decreasing both receptors on the dermal cells. Estrogen specifically and preferentially promoted spleen chemokine protein expression for MCP-1 and MCP-3, while having no effect on dermal protein expression for these chemokines. Estradiol-mediated effects on splenic chemokines were abrogated by tamoxifen and ICI 182,780. The gender-specific increase in lymphocyte homing to spleen may be attributable, at least in part, to tissue-specific estrogen-mediated effects on microvascular endothelial cells.

Animals↗

PubMed2004

Potential beneficial metabolic interactions between tamoxifen and isoflavones via cytochrome P450-mediated pathways in female rat liver microsomes.

PURPOSE: This study aims to evaluate a cytochrome P450-based tamoxifen-isoflavone interaction and to determine the mechanisms responsible for inhibitory effects of isoflavones (e.g., genistein) on the formation of alpha-hydroxytamoxifen. METHODS: Metabolism studies were performed in vitro using female rat liver microsomes. The effects of genistein and an isoflavone mixture on tamoxifen metabolism and the inhibition mechanism were determined using standard kinetic analysis, preincubation, and selective chemical inhibitors of P450. RESULTS: Metabolism of tamoxifen was saturable with Km values of 4.9+/-0.6, 14.6+/-2.2, 25+/-5.9 microM and Vmax values of 34.7+/-1.4, 297.5+/-19.2, 1867+/-231 pmol min(-1) mg(-1) for a-hydroxylation, N-desmethylation, and N-oxidation, respectively. Genistein (25 microM) inhibited alpha-hydroxylation at 2.5 microM tamoxifen by 64% (p < 0.001) but did not affect the 4-hydroxylation, N-desmethylation, and N-oxidation. A combination of three (genistein, daidzein, and glycitein) to five isoflavones (plus biochanin A and formononetin) inhibited tamoxifen alpha-hydroxylation to a greater extent but did not decrease the formation of identified metabolites. The inhibition on alpha-hydroxylation by genistein was mixed-typed with a Ki, value of 10.6 microM. Studies using selective chemical inhibitors showed that tamoxifen alpha-hydroxylation was mainly mediated by rat CYP1A2 and CYP3A1/2 and that genistein 3'-hydroxylation was mainly mediated by rat CYP1A2, CYP2C6 and CYP2D1. CONCLUSIONS: Genistein and its isoflavone analogs have the potential to decrease side effects of tamoxifen through metabolic interactions that inhibit the formation of a-hydroxytamoxifen via inhibition of CYP1A2.

Algorithms↗

PubMed2004

Pharmacokinetics of three organic nitrates in Chinese healthy male volunteers.

Eighteen Chinese male subjects completed a single-blind, randomized, three-treatment, three-period, cross-over study. In each treatment phase, subjects received a single dose of 20 mg isosorbide dinitrate (CAS 87-33-2, ISDN) intravenous infusion, 20 mg isosorbide 5-mononitrate (CAS 16051-77-7, 5-ISMN) tablet or 20 mg isosorbide 5-mononitrate intravenous infusion. Each consecutive dosing was separated by a washout period of 7 days. Following each dosing, venous blood samples were collected over a period of 16 h. Plasma concentrations of ISDN and its two active metabolites isosorbide 2-mononitrate (2-ISMN), 5-ISMN had been measured by a validated gas chromatographic method. Various pharmacokinetic parameters including AUC0-t, AUC0-infinity, Cmax, tmax, t1/2, Kelm and MRT were determined for the three formulations and found to be in good agreement with literature values. AUC0-t and AUC0-infinity of 5-ISMN tablet and intravenous infusion were 2694 +/- 496 ng x ml(-1) x h vs. 2548 +/- 556 ng x ml(-1) x h and 3266 +/- 624 ng x ml(-1) x h vs. 3178 +/- 769 ng x ml(-1) x h, respectively, and the relative bioavailability of 5-ISMN tablet was 105 +/- 20%. As compared with 5-ISMN intravenous infusion, ISDN can rapidly reach the plateau concentration and metabolize to its active metabolites 5-ISMN and 2-ISMN, which both have vasodilator effect. The results of this study suggest that as evaluated from the pharmacokinetic profiles of the three formulations, 5-ISMN tablet and ISDN intravenous infusion are ideal vasodilators and anti-angina drugs especially in acute conditions due to their rapid onset and long duration of action.

Administration, Oral↗

PubMed2004

Quality, labeling accuracy, and cost comparison of purified soy isoflavonoid products.

OBJECTIVES: To evaluate the labeling accuracy and product uniformity of available soy isoflavone products in the eastern Washington State region for 13 products and to perform a cost comparison based on the isoflavone content in milligrams for 11 products. DESIGN: Thirteen (13) isoflavone products (7 tablet and 6 capsule formulations) were randomly obtained from health food, grocery, and pharmacy outlets in eastern Washington State. Four different samples of the same product were extracted using 75% ethanol. Each sample was analyzed for isoflavone content using a gradient high-performance liquid chromatography (HPLC) method. Pure isoflavonoid standards were used to quantify the content of genistein, daidzein, and glycitein and their respective glycosides. The amount of total isoflavonoids per purchased product was then divided into its purchase price in order to make cost comparisons between the products based on a 50 mg/d dose. RESULTS: The weight variation within each product was generally small (<4%). However, there was significant variability in the composition of the products. Only 4 of the 13 products contained at least 90% of the isoflavone content claimed on the label and 2 of products contained impurities in the HPLC chromatogram that exceeded 40%. There was no difference in the total isoflavonoid contents of the 2 identical products made by the same manufacturer, but the percentages of the main components had changed significantly over time. Based on a 50-mg isoflavone per day dose, the cost of a 30-day supply ranged from $3.20 to $65.88. CONCLUSION: There is a lack of uniformity among the products tested and the majority (67%) of the products contained less than 90% of labeled amounts. There is significant variability in the compositions between the products and in the composition of the same product over time. Consumers cannot trust isoflavonoid product labels to represent the product's content accurately or that product pricing is a reflection of isoflavone content.

Chromatography, High Pressure Liquid↗

PubMed2004

Characterization of molecular events in a series of bladder urothelial carcinoma cell lines with progressive resistance to arsenic trioxide.

Our previous studies have shown that arsenic trioxide (As2O3), a novel anti-cancer agent, may be active against urothelial carcinomas. A series of bladder urothelial carcinoma cells with progressive As2O3 resistance were established and studied to reveal molecular events in relation to the mechanisms of resistance to As2O3. A sensitive parental line (NTUB1) and three As2O3-resistant sublines (NTUB1/As) were used with their IC50s being 0.9, 1.2, 2.5 and 4.9 microM, respectively. Cellular resistance to As2O3 was associated with a lowered proliferation profile (increased p53 and p21Waf1/Cip1 and decreased c-Myc levels) and a greater resistance to apoptosis (elevated Bcl-2 levels). Cells with a stronger resistance had higher expressions of superoxide dismutase (Cu/Zn) and hMSH2 (but not hMLH1). GSH contents were up-regulated in resistant cells in a dose-dependent manner. The DNA-binding activities of NF-kappaB and AP-1 were down-regulated in resistant cells in a dose-dependent manner. Profound molecular alterations occur during the acquisition of secondary As2O3 resistance. Our in vitro cellular model may help to reveal resistance mechanisms to As2O3 in bladder urothelial carcinoma cells.

Apoptosis↗

PubMed2004

Effects of diabetes on female voiding behavior.

PURPOSE: We studied voiding behavior in women with type 2 diabetes vs nondiabetic female controls and examined factors associated with voiding dysfunction in patients with diabetes. MATERIALS AND METHODS: After eliminating coexisting medical factors that could affect voiding function we evaluated voiding behaviors in 194 female patients with diabetes treated regularly at a diabetic clinic and 162 control women using a lower urinary tract symptom questionnaire based mainly on the American Urological Association Symptom Index questionnaire and free flow analyses with post-void residual urine estimates. Emptying efficiency was defined as 100% x volume voided/(volume voided + post-void residual urine). RESULTS: Compared with controls patients with diabetes had significantly higher nocturia scores (p = 0.003), weaker urinary streams (p = 0.02), less voided volumes (220 +/- 97 vs 280 +/- 104 ml, p = 0.04) and lower maximal flow rates (19.4 +/- 8.4 vs 25.9 +/- 8.5 ml per second, p <0.001). Remarkable residual urine (100 ml or greater) was detected in 1.8% of controls vs 13.9% of patients. After controlling for age and voided volume diabetes was significantly associated with a decrease in baseline maximum flow of 4.5 ml per second (95% CI 2.9 to 6.2). In patients with diabetes peripheral neuropathy was an independent factor associated with the decrease in emptying efficiency (p = 0.03). CONCLUSIONS: Diabetes significantly altered voiding patterns in a significant proportion of women treated at the diabetic clinic. Peripheral neuropathy is an important factor associated with diabetic voiding dysfunction.

Adult↗

PubMed2004

Specific interaction between the classical swine fever virus NS5B protein and the viral genome.

The NS5B protein of the classical swine fever virus (CSFV) is the RNA-dependent RNA polymerase of the virus and is able to catalyze the viral genome replication. The 3' untranslated region is most likely involved in regulation of the Pestivirus genome replication. However, little is known about the interaction between the CSFV NS5B protein and the viral genome. We used different RNA templates derived from the plus-strand viral genome, or the minus-strand viral genome and the CSFV NS5B protein obtained from the Escherichia coli expression system to address this problem. We first showed that the viral NS5B protein formed a complex with the plus-strand genome through the genomic 3' UTR and that the NS5B protein was also able to bind the minus-strand 3' UTR. Moreover, it was found that viral NS5B protein bound the minus-strand 3' UTR more efficiently than the plus-strand 3' UTR. Further, we observed that the plus-strand 3' UTR with deletion of CCCGG or 21 continuous nucleotides at its 3' terminal had no binding activity and also lost the activity for initiation of minus-strand RNA synthesis, which similarly occurred in the minus-strand 3' UTR with CATATGCTC or the 21 nucleotide fragment deleted from the 3' terminal. Therefore, it is indicated that the 3' CCCGG sequence of the plus-strand 3' UTR, and the 3' CATATGCTC fragment of the minus-strand are essential to in vitro synthesis of the minus-strand RNA and the plus-strand RNA, respectively. The same conclusion is also appropriate for the 3' 21 nucleotide terminal site of both the 3' UTRs.

3' Untranslated Regions↗

PubMed2004

The trend of managing prostate cancer in Taiwan.

BACKGROUND: The purpose of this study is to investigate the current trends of Taiwanese urologists in managing prostate cancer (CaP). This will help us to establish our own consensus and recommend appropriate treatment options to the related patients. METHODS: From November 2000 to April 2001, a questionnaire concerning the alertness of detecting CaP, diagnostic tools used for establishing the staging of CaP before radical surgery, the tolerated age for surgery and the use of hormone therapy for advanced CaP was mailed to the 465 urologists in active practice in the Taiwan area. RESULTS: A total of 240 (51.6%) physicians responded to our questionnaire. 89.1% of the respondents would add serum prostatic-specific antigen (PSA) to detect suspected malignancy during the work-up for benign prostatic hyperplasia in their daily practice. About three quarters of the respondents adopted free/total PSA in assisting the decision for prostate biopsy. 78% require a bone scan before radical surgery even when PSA is less than 10 ng/mL and the age tolerated for radical surgery is 75 years. 60.8% still believed that maximal androgen blockade is effective for advanced CaP. CONCLUSIONS: The trend of treating CaP provides a useful insight into the variations in clinical practice of Taiwanese urologists and may help to develop a more widely accepted guideline by our urological community.

Humans↗

PubMed2004

Cellular reactions of osteoblasts to micron- and submicron-scale porous structures of titanium surfaces.

Osteoblast reactions to topographic structures of titanium play a key role in host tissue responses and the final osseointegration. Since it is difficult to fabricate micro- and nano-scale structures on titanium surfaces, little is known about the mechanism whereby the topography of titanium surfaces exerts its effects on cell behavior at the cellular level. In the present study, the titanium surface was structured in micron- and submicron-scale ranges by anodic oxidation in either 0.2 M H3PO4 or 0.03 M calcium glycerophosphate with 0.15 calcium acetate. The average dimensions of pores in the structured surface were about 0.5 and 2 microm in diameter, with roughness averaging at 0.2 and 0.4 microm, respectively. Enhanced attachment of cells (SaOS-2) was shown on micron- and submicron-scale structures. Initial cell reactions to different titanium surfaces, e.g. the development of the actin-containing structures, are determined by the different morphology of the surfaces. It is demonstrated that on either micron- or submicron-structured surfaces, many well-developed filopodia were observed to be primary adhesion structures in cell-substrate interactions, and some of them entered pores using their distinct tips or points along their length for initial attachment. Therefore, porous structures at either micro- or submicrometre scale supply positive guidance cues for anchorage-dependent cells to attach, leading to enhanced cell attachment. In contrast, the cells attached to a smooth titanium surface by focal contacts around their periphery as predominant adhesion structures, since repulsive signals from the environment led to retraction of the filopodia back to the cell bodies. These cells showed well-organized stress fibres, which exert tension across the cell body, resulting in flattened cells.

Biocompatible Materials↗

PubMed2004

Central immunotolerance in transgenic mice expressing a foreign antigen under control of the rhodopsin promoter.

PURPOSE: Different conclusions have been reached in recent studies concerning the immune response or tolerance of transgenic (Tg) mice expressing foreign antigens under control of retinal antigen promoters. The present study was aimed at analyzing the state of tolerance in Tg mice expressing hen egg lysozyme (HEL) under control of the rhodopsin promoter. METHODS: Tg mice expressing HEL under control of the rhodopsin promoter (RhHEL-Tg) were generated and tested by conventional methods for immune responses against HEL. These Tg mice were also mated with Tg mice expressing HEL-specific receptor on their T lymphocytes and the double-Tg mice were examined for increased apoptosis in their thymi by the TUNEL assay, as well as for loss of HEL-specific T cells, by flow cytometry and proliferative response. The presence of HEL mRNA in mouse thymi was determined by RT-PCR. RESULTS: RhHEL-Tg mice developed tolerance to HEL, shown by reduced cellular and humoral responses to HEL, as well as by the failure of ocular inflammation to develop after immunization with HEL. RhHEL-Tg mice expressed HEL mRNA in their thymus, and the tolerogenic mechanism in these mice was shown to be thymic deletion of HEL-specific T cells by the following observations in the double-Tg mice: (1) increased apoptosis in their thymi, (2) remarkable reduction in the proportion of the HEL-specific T cells, and (3) loss of lymphocyte response to low concentrations of HEL. CONCLUSIONS: Tg mice expressing HEL under control of the rhodopsin promoter develop a tolerance for the foreign antigen, apparently as a result of thymic expression of HEL and deletion of T cells specific to this antigen.

Animals↗

PubMed2004

Apoptosis in cerebral ischemia: executional and regulatory signaling mechanisms.

Programmed cell death, often in the form of apoptosis, is an important contributing mechanism in the pathogenesis of ischemic brain injury. Depending on the severity of the insult and the stage of the injury, the executional pathways that are directly responsible for cell death and the signaling mechanisms that participate in the regulation of these death pathways may vary. It is likely that molecular or pharmacological targeting of the upstream signaling mechanisms that control the death executional pathways may offer opportunities for more complete and long-term neuroprotection. This review summarizes the recent advancements in the understanding of the executional and regulatory signaling mechanisms in ischemic brain injury.

Animals↗

PubMed2004

Molar absorptivities of glucose and other biological molecules in aqueous solutions over the first overtone and combination regions of the near-infrared spectrum.

Molar absorptivities are measured for water, glucose, alanine, ascorbate, lactate, triacetin, and urea in the near-infrared spectral region at 37 degrees C. Values are based on the Beer-Lambert law and cover the first overtone (1550-1850 nm; 6450-5400 cm(-1)) and combination (2000-2500 nm; 4000-5000 cm(-1)) spectral windows through aqueous media. Accurate calculations demand accounting for the impact of water displacement upon dissolution of solute. In this regard, water displacement coefficients are measured and reported for each solute. First overtone absorptivities range from 2 to 7 x 10(-5) mM(-1)mm(-1) for all solutes except urea, for which absorptivity values are below 0.5 x 10(-5) mM(-1) mm(-1) across this spectral range. Molar absorptivities over the combination spectral region range from 0.8 to 3.2 x 10(-4) mM(-1) mm(-1), which is a factor of four to five greater than the first overtone absorptivities. Accuracy of the measured values is assessed by comparing calculated or modeled spectra with spectra measured from standard solutions. This comparison reveals accurately modeled spectra in terms of magnitude and position of solute absorption bands. Both actual and modeled spectra from glucose solutions reveal positive and negative absorbance values depending on the measurement wavelength. It is shown that the net absorbance of light is controlled by the magnitude of the absorptivity of glucose compared to the product of the absorptivity of water and the water displacement coefficient for glucose.

Glucose↗