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Biomedical subjects

C N Chang

Publications and source records attributed to C N Chang.

At least 19 recordsLinked to original sources
PubMed2001

Hyperbaric oxygen treatment decreases post-ischemic neurotrophin-3 mRNA down-regulation in the rat hippocampus.

The therapeutic effect of hyperbaric oxygen (HBO) on ischemic injury was investigated using in situ hybridization to detect the mRNA expression of neurotrophin-3 (NT-3), which is thought to play a crucial role in protecting against neuronal death induced by brain ischemia. The rats under investigation were subjected to 10 min transient forebrain ischemia, and subsequently exposed to HBO (100% oxygen, 2.5 atm absolute) for 2 h. Levels of NT-3 mRNA in the CA1, CA2 and CA3 regions, and the dentate gyrus of the hippocampus were measured after various reperfusion periods. Neuronal death in the hippocampal CA1 region was also measured by Nissl staining, seven days post ischemia. The results demonstrated that HBO treatment significantly reduced the ischemia-induced down-regulation of the NT-3 mRNA level at 4 h post ischemia, and significantly increased cell survival 7 days after reperfusion. The findings suggest that an HBO treatment maintaining the NT-3 mRNA level in the hippocampus can be beneficial to the ischemic brain within a certain time frame.

Animals↗
PubMed2001

The study of Central Taiwan particles concentration variations during earthquake period.

Ambient particle concentration was taken on the traffic sampling site over the Chung-Chi Road over the bridge (CCROB) in front of Hungkuang Institute of Technology (HKIT). The sampling time was from August 1999 to December 1999. During the sampling period, Taiwan's biggest earthquake in more than a century registered 7.3 on the Richter scale (Taiwan Chi-Chi Earthquake). Besides, there are more than 20,000 aftershocks following the Taiwan Chi-Chi Earthquake within 3 months. Thus, the mass concentration of particles with aerodynamic diameters smaller than 2.5 microm (PM2.5) and PM2.5-10 was also collected then compared with the total mass concentration of suspended particles (TSP) in this study. The average TSP, PM2.5-10, and PM2.5 concentrations are 106, 24.6, and 58.0 microg/m3, respectively, after the Taiwan Chi-Chi Earthquake. The average TSP concentrations before and after Taiwan Chi-Chi Earthquake were 69.6 and 127 microg/ m3, respectively. In addition, statistical analysis of the PM10 data from this study and EPA in 1999 yielded a Tstatistic of 0.147, which is smaller than t(0.975,18) = 2.101. It is indicated that there was no significant difference. So, the PM10 concentrations measured after Taiwan Chi-Chi Earthquake in this study were also greater than those data previously obtained from Taiwan EPA in the same region of this area. The relationships between TSP, PM10, PM2.5-10, and PM2.5 particle concentrations and wind speed (R2) are .77, .59, .58, .58, respectively. And the ratios of PM2.5/PM25-10, PM2.5/PM10, and PM10/TSP are 221%, 67.2%, 58.0%, respectively. The average ratios of PM2.5/PM2.5-10 and PM2.5/PM10 increase by about 120% and 17%. It indicated that the fine-particles concentration increases compared to the coarse-particles concentration after 921 Taiwan Chi-Chi Earthquake. And the proposed reasons are that local motor vehicle emissions combined the fine particles transported from the Chi-Chi epicenter. More importantly, the wind direction was mainly blown from southeastern part. These two main factors enhance the fine-particles concentration in this area.

Air Pollutants↗
PubMed2001

Membranous obstruction of the fourth ventricle outlet. A case report.

We report the case of a 15-year-old girl with amenorrhea and a several-week history of headache. After the diagnosis of membranous obstruction of the foramen of Magendie suggested by MRI, suboccipital craniotomy for removal of the membrane was carried out. The patient made an excellent postoperative recovery, and postoperative phase-contrast MRI demonstrated patent cerebrospinal fluid (CSF) pathways at the level of the foramina of Magendie and Luschka. We believe that this case is of interest because of the unequivocal evidence on MRI studies of the occlusion of the foramen of Magendie preoperatively, and because of the dramatic postoperative MRI findings demonstrating the effectiveness of the surgical procedure both in terms of ventricular size and CSF flow characterization.

Adolescent↗
PubMed2001

Cerebellar metastasis from papillary serous adenocarcinoma of the ovary mimicking Ménière's disease. A case report.

BACKGROUND: In rare cases, cerebellar metastasis originating in serous papillary adenocarcinoma of the ovary can mimick Ménière's disease. CASE: A 51-year-old woman, with complete remission after optimal maximal debulking and chemotherapy for an International Federation of Gynecology and Obstetrics IIIc primary ovarian carcinoma, presented with nausea, vomiting, vertigo and headache 18 months after surgery. Investigations revealed a solitary cerebellar cystic mass, 4.6 x 4.0 x 3.2 cm. Gross total excision of the cerebellar lesion followed by brain irradiation resulted in complete resolution of her symptoms. Histology showed a metastatic tumor consistent with the primary ovarian carcinoma. CONCLUSION: In an atypical presentation in patients with metastatic ovarian carcinoma, thorough investigations should be done to rule out or confirm brain metastasis, which can be aggressively managed to prevent serious consequences and improve outcome.

Adenocarcinoma, Papillary↗
PubMed2001

The feasible sequential control strategy of treating high strength organic nitrogen wastewater with sequencing batch biofilm reactor.

The bio-kinetics and feasible sequential control strategy of treating high strength organic carbon and nitrogen wastewater were investigated by conducting the ABS manufacturing wastewater in a series of Sequencing Batch Biofilm Reactors (SBBRs). The on-line ORP, pH, and DO monitoring parameters were applied to identify the feature-points when ammonification, nitrification, and denitrification ends. The carbonaceous matter removal kinetics in the anaerobic and aerobic reaction stages can be expressed by the Michaelis-Menten equation. High efficiency of organic carbon removal and organic nitrogen ammonification in the anaerobic stage can eliminate the substrate competition and activation inhibition to nitrifying organisms in the following aerobic stage. In the sequencing nitrogen removal processes, the producing time and system ORP values of these feature-points have good function relationships with the influent COD loading rates of SBBR, which can be integrated into a set-point (set-time and set-ORP) sequential control strategy of nitrogen removal. The automatic control operation results revealed ORP was one of the major control parameters of the sequencing nitrogen removal process in SBBR system and high overall removal efficiency were obtained.

Aerobiosis↗
PubMed2001

Development of a real-time control strategy with artificial neural network for automatic control of a continuous-flow sequencing batch reactor.

The purpose of this study is to develop a reliable and effective real-time control strategy by integrating artificial neural network (ANN) process models to perform automatic operation of a dynamic continuous-flow SBR system. The ANN process models, including ORP/pH simulation models and water quality ([NH4(+)-N] and [NOx(-)-N]) prediction models, can assist in real-time searching the ORP and pH control points and evaluating the operation performances of aerobic nitrification and anoxic denitrification operation phases. Since the major biological nitrogen removal mechanisms were controlled at nitrification (NH4(+)-N-->NO2(-)-N) and denitritification (NO2(-)-N-->N2) stages, as well as the phosphorus uptake and release could be completely controlled during aerobic and anoxic operation phases, the system operation performances under this ANN real-time control system revealed that both the aeration time and overall hydraulic retention time could be shortened to about 1.9-2.5 and 4.8-6.2 hrs/cycle respectively. The removal efficiencies of COD, ammonia nitrogen, total nitrogen, and phosphate were 98%, 98%, 97%, and 84% respectively, which were more effective and efficient than under conventional fixed-time control approach.

Ammonia↗
PubMed2001

Proton magnetic resonance spectroscopy of cerebral glioma after irradiation.

BACKGROUND: Conventional magnetic resonance imaging (MRI) is commonly employed to assess cerebral gliomas after radiotherapy, but it cannot always differentiate tumor regrowth from post-irradiation changes. In this study, we utilized magnetic resonance spectroscopy (MRS) to evaluate changes in cerebral metabolites in patients with a cerebral glioma after irradiation. METHODS: Over a period of 3 years, we performed MRS after MRI whenever soft tissue masses were found on magnetic resonance (MR) images. A total of 122 MR spectra of 58 patients was used for analysis. Spectral interpretations were based on integral values of the N-acetylaspartate (NAA) and choline (Cho) compounds relative to phosphocreatine/creatine (Cr). RESULTS: Our MRS study showed that higher Cho/Cr ratios occurred in regrowing gliomas than for stable diseases (range, 0.9 to 9.5 vs. 0.4 to 2.1; mean, 3.0 vs. 1.2). A greater increment in the Cho/Cr ratio between successive studies was also noted in regrowing gliomas than for stable disease (range, 41% to 87% vs. < 32%). No significant differences in NAA/Cr ratios or lactate were found between these 2 groups. None of our patients exhibited abnormal MR spectra in the mirror area of the contralateral brain. CONCLUSION: MRS provides valuable information about the metabolism of irradiated gliomas and can be used to exclude radiation encephalopathy of the contralateral brain. Cho is the most reliable indicator of a regrowing glioma. A high Cho/Cr ratio or substantial elevation in the Cho/Cr ratio between serial studies increases the likelihood of tumor regrowth. However, lower Cho/Cr ratios were inconclusive for determining if tumor regrowth or a stable process was occurring.

Brain↗
PubMed2001

Lateralization and prognostic value of proton magnetic resonance spectroscopy in patients with intractable temporal lobe epilepsy.

BACKGROUND: The aims of this prospective study were to investigate the stability of hippocampal metabolite ratios obtained by proton magnetic resonance spectroscopy (MRS), to evaluate the ability of MRS to determine the pre-surgical lateralization of seizure focus, and to assess the relationship between MRS results and postoperative outcomes in patients with intractable temporal lobe epilepsy. METHODS: Within- and between-acquisition variations were evaluated in 30 control subjects, using the chemical-shift imaging technique. The most stable metabolite ratio was then applied for pre-surgical evaluation of 14 patients with intractable temporal lobe epilepsy. RESULTS: The ratio between N-acetylaspartate (NAA) and choline-containing compounds (Cho) plus creatine-phosphocreatine (Cr), i.e., NAA/(Cho+Cr), had an overall smaller percentage change between measurements (13%-28%) than did the other ratios: NAA/Cho (18%-37%), NAA/Cr (11%-60%), and Cho/Cr (19%-51%). With a mean follow-up period of 27 months (range, 12-55 months) after an anterior temporal lobectomy, 10 patients were in Engel s class I (71%), 2 were in class II (14%), and 2 were in class III (14%). Lateralization by MRS was consistent with the operation side in 11 (79%) patients, including class I in 8 patients, class II in 1 patient, and class III in 2 patients. Ranges of reduced NAA/(Cho+Cr) values were similar between patients with different post-surgical outcomes: 0.26-0.47 for class I, 0.40-0.45 for class II, and 0.34-0.40 for class III (p=0.651). CONCLUSIONS: Proton MRS may be helpful in pre-surgical lateralization of the seizure focus in patients with intractable temporal lobe epilepsy; however, it cannot provide prognostic information about postoperative seizure control.

Adolescent↗
PubMed2000

Profiles of gonadal development, sex steroids, aromatase activity, and gonadotropin II in the controlled sex change of protandrous black porgy, Acanthopagrus schlegeli Bleeker.

The objectives of the present study were to investigate the effects of oral administration of estradiol-17 beta (E(2)) on the sex steroids and gonadotropin II (GTH II) in plasma, aromatase activity in gonad and brain, and sex change in protandrous black porgy, Acanthopagus schlegeli Bleeker. Two-year-old black porgy were divided into two groups, one fed a control diet and the other a diet mixed with E(2) (4.0 mg/kg feed) for 7 months. Significantly higher GSI was observed in the E(2) group. Fish treated with E(2) showed complete suppression of spermatogenesis and spermiation and induced sex change with vitellogenic oocytes and large primary oocytes. Lower levels of plasma 11-ketotestosterone and higher levels of plasma vitellogenin were shown in the E(2) group. Higher gonadal aromatase activity in concordance with elevated plasma levels of GTH II was observed in the E(2) group. The highest aromatase activity in the forebrain in the control group was observed in January. Higher aromatase activity in forebrain, midbrain, and hindbrain was also detected in the E(2) group than the control group. The change of aromatase activity in brain was more susceptible than that in gonad. The data showed that the increase of plasma GTH II levels and gonadal aromatase activity may be important to the controlled sex change by administration in black porgy.

Animals↗
PubMed2000

Comparison of particulate mass, chemical species for urban, suburban and rural areas in central Taiwan, Taichung.

Aerosol samples for PM2.5, PM(2.5-10) and TSP were collected from June to September 1998 and from February to March 1999 in central Taiwan. Ion chromatography was used to analyze the acidic anions: sulfate, nitrate and chloride in the Universal samples. The ratios of fine particle concentrations to coarse particle concentrations displayed that the fine particle concentrations are almost greater than that of coarse particle concentrations in Taichung area. The average concentrations of PM2.5, PM(2.5-10) and TSP in urban sites are higher than in suburban and rural sites at both daytime and night-time. Chloride dominated in the coarse mode in daytime and in fine mode in night-time. Nitrate can be found in both the coarse and fine modes. Sulfate dominated in fine mode in both daytime and night-time.

Air Pollutants↗
PubMed2000

The study of TSP, PM(2.5-10) and PM2.5 during Taiwan Chi-Chi Earthquake in the traffic site of central Taiwan, Taichung.

Ambient particle concentration was taken on the traffic sampling site over the Chung-Chi Road over bridge (CCROB) in front of Hungkuang Institute of Technology (HKIT). The sampling time was from August 1999 to December 1999. During the sampling period, Taiwan's biggest earthquake in more than a century registered 7.3 on the Richter scale (Taiwan Chi-Chi Earthquake). Besides, there were more than 20,000 aftershocks that followed the Taiwan Chi-Chi Earthquake within three months. Thus, the PM2.5, PM(2.5-10) particle concentrations were also collected then and compared with total suspended particle (TSP) in this study. The average PM(2.5-10), PM2.5 and TSP concentrations are 24.6, 58.0 and 106 microg/m3, respectively, after the Taiwan Chi-Chi Earthquake. The average TSP concentrations before and after Taiwan Chi-Chi Earthquake were 70 and 127 microg/m3, respectively. It is clearly shown that the average concentration of TSP after Taiwan Chi-Chi Earthquake was about 1.8 times as that of TSP concentration before Taiwan Chi-Chi Earthquake in the traffic site of central Taiwan. And the ratios of PM2.5/PM(2.5-10), PM2.5/PM10 and PM2.5/TSP are 2.2%, 67.2%, 38.9%, respectively. The results also indicated about Chi-Chi fine particle concentration (PM25) and the TSP increases in the traffic site of central Taiwan after Taiwan Chi-Chi Earthquake.

Air Pollutants↗
PubMed2000

The study of fine and coarse particles, and metallic elements for the daytime and night-time in a suburban area of central Taiwan, Taichung.

Daily average concentrations of fine and coarse particulates, and TSP samples have been measured simultaneously at daytime and night-time periods by using Universal and PS-1 sampler in a suburban area of central Taiwan from June to August 1998. The samples were analyzed by atomic absorption spectrometry to determine the fine and coarse particulate concentrations of metallic elements (Ca, Fe, Mn, Pb, Cu, Zn and Cr). The concentration of PM2.5 and TSP showed a decreased trend for the daytime period. The fine particle concentrations were about two times as that of coarse particulate concentrations. The averaged fine particulate concentrations at daytime are higher than at night-time. Ca and Fe were mostly in the coarse particulate mode. The correlation coefficients were 0.63 and 0.69 for elements Ca and Fe in the coarse particle mode for day and night periods. Pb showed a similar distribution ratio with Mn for the fine to coarse particle ratios at both day and night period. Pb and Mn are highly correlated for the day (R = 0.78) and night period (R = 0.61) at particle size <2.5 microm. Cu and Zn were mainly in fine particles at both day and night period. Fe and Ca consist of the major parts of all the elements. Elemental Mn is the lowest among the rest of the heavy metals.

Air Pollutants↗
PubMed2000

Engineering autogenous cartilage in the shape of a helix using an injectable hydrogel scaffold.

OBJECTIVE: Previous successful efforts to tissue engineer cartilage for an auricle have used an immunocompromised nude mouse xenograft model. Subsequent efforts in an immunocompetent autogenous animal model have been less successful because of an inflammatory response directed against the foreign scaffold polymer used to provide an auricular shape. We studied an alternative polymer material and surgical technique to engineer autogenous cartilage in the shape of a human ear helix using injectable hydrogel scaffolding, Pluronic F-127 (polyethylene oxide and polypropylene oxide). SUBJECT: Yorkshire swine. MATERIAL AND METHODS: Fresh autogenous chondrocytes were suspended in a biodegradable, biocompatible co-polymer hydrogel, Pluronic F-127, at a concentration of 3 x 10(7) cells/mL. To support the contour of the implant, a skin fold channel in the shape of the helix of a human ear was created in the skin in three sites on the ventral surface of the animal. The cell-hydrogel suspension was injected through the skin fold channel. For controls, injections were made into identical channels using either cells alone or the Pluronic F-127 without cells. After 10 weeks, the specimens were excised and examined both grossly and histologically. RESULTS: Grossly, all implants retained a helical-like shape. Excised specimens possessed flexible characteristics consistent with elastic cartilage. The specimens could be folded and twisted and on release of mechanical pressure would instantly return to the original shape. Histological evaluation of the implants using H&E, Safranin O, trichrome blue, and Verhoeff's stains demonstrated findings consistent with mature elastic cartilage. Control injection of hydrogel alone demonstrated no evidence of cartilage formation and control injection of chondrocytes alone showed evidence only of disassociated elastic cartilage. CONCLUSION: Injection of autologous porcine auricular chondrocytes suspended in a biodegradable, biocompatible hydrogel of Pluronic F-127 resulted in the formation of cartilage tissue in the approximate size and shape of a human ear helix. This preliminary method extends the concept of auricular tissue engineering from an immunocompromised xenograft animal model to an immunocompetent autologous animal model.

Animals↗
PubMed2000

Craniofacial resection for tumors of the nasal cavity and paranasal sinuses.

BACKGROUND AND PURPOSE: Craniofacial resection provides multidirectional approaches to remove nasal and paranasal tumors that involve the skull base. The purpose of this study was to determine the survival and local control rate in patients undergoing craniofacial resection for tumors of the nasal cavity, paranasal sinuses, and adjacent areas. METHODS: The medical records of 30 consecutive patients who had undergone craniofacial resection for tumors of the nasal cavity, paranasal sinuses, and adjacent areas were reviewed. The extent of disease, treatment results, complications, and prognoses were analyzed. RESULTS: Lesions were malignant in 28 patients and benign in two. Sixteen of the patients had dural or intradural involvement. There was no surgical mortality, and the rate of surgical morbidity was 7%. The 2-year survival of the 28 patients with malignancies was 46% and the mean follow-up time was 35 months. Local control was achieved in 53% of patients. Nine of 16 patients with dural or intradural invasion had a mean survival time of 17 months. There was no significant difference in the frequency of local control between previously treated and untreated patients. Patients who had a clear margin showed significantly better local control than those with an involved or questionable margin. CONCLUSIONS: Tumors of the nasal cavity and paranasal sinus that involve the skull base can be effectively treated using craniofacial resection, with a reasonable survival and low complication rate.

Adolescent↗
PubMed1999

Characterization of chemical species in PM2.5 and PM10 aerosols in suburban and rural sites of central Taiwan.

Aerosol samples for PM2.5 (particulate matter with aerodynamic diameters less than 2.5 microns), PM2.5-10 (particulate matter with aerodynamic diameters between 2.5 and 10 microns) and TSP were collected from June to September 1998 at THU (suburban) and HKIT (rural) sites in central Taiwan. The ratios of PM2.5/PM10 averaged 0.70 for the daytime and 0.63 for the nighttime at THU, respectively. At HKIT, the PM2.5/PM10 ratios averaged 0.56 for the daytime and 0.72 in the nighttime, respectively. These results indicated that the PM2.5 concentrations contribute the majority of the PM10 concentration and PM10 concentrations contribute the majority of the TSP at both sites. The averaged PM2.5 concentrations at THU are higher than those measured at HKIT during the daytime period. However, the average PM2.5-10 concentrations in THU are lower than those measured at HKIT during nighttime. The samples collected were also analyzed by atomic absorption spectrophotometry for the elemental analysis of Ca, Fe, Pb, Zn, Cu, Mn and Cr. Meanwhile ion chromatography was used to analyze for the water-soluble ions: sulphate, nitrate and chloride in the Universal samples. The concentrations of heavy metals in PM10 during daytime were all higher than nighttime at THU. However, the averaged concentrations of metal elements in PM10 during day and night period were distributed irregularly at HKIT. The results indicated that for metal elements collected at HKIT have different emission sources. The concentrations of metal elements during daytime in PM10 at THU were generally higher than HKIT. The phenomena owing to the averaged PM2.5 particle concentrations at THU (suburban) were higher than those measured at HKIT (rural) and PM2.5 occupied the major portions of PM10 for both sites during the day period. For anion species, there are no significant differences between day and night period in PM10 concentrations at both suburban and rural sites.

Aerosols↗
PubMed1999

The characteristic study of TSP, PM2.5-10 and PM2.5 in the rural site of central Taiwan.

The total suspended particle (TSP), PM2.5-10 (aerodynamic diameter less than 10 microns) and PM2.5 concentration (aerodynamic diameter less than 2.5 microns) concentrations were sampled by PS-1 and Universal sampler on the roof (25 m) of the Medical and Engineering Building in the campus of Hungkuang Institute of Technology (HKIT) which is located at a height of 500 m on Da Du Mountain. The results indicated that average TSP, PM2.5-10 and PM2.5 concentrations are 0.42, 0.34 and 0.019 mg/m3 in the day time, respectively and are 0.32, 0.26 and 0.017 mg/m3 in the night time, respectively. The ratios of PM2.5-10/TSP were from 76% to 85% and from 50% to 91% for day and night period, respectively. It indicated that the major composition in the total suspended particles was PM2.5-10 in the rural site. The relationship between TSP and PM2.5-10 is TSP = 1.16PM2.5-10 + 0.027 and TSP = 1.01 PM2.5-10 + 0.058 in the day and night time, respectively. The correlation coefficient (R2) is 0.98 and 0.97 for day and night period, respectively. The relationship between PM2.5-10 and PM2.5 is PM2.5 = 0.0005PM2.5-10 + 0.019 and PM2.5 = 0.037PM2.5-10 + 0.0076 in the day and night period, respectively. The correlation coefficient (R2) is 3E-5 and 0.67 for day and night period, respectively. The relationships between TSP, PM2.5-10, PM2.5 particle concentrations and wind speed (R2) in the day time are 0.71, 0.64, 0.43, respectively and are 0.83, 0.79, 0.57, respectively in the night time. The proposed reasons are that there are more activities caused by people (students) and natural living animals which absorbed some of the particles during the day time. Thus, the correlation coefficients for the night time are better than those of day time. The particle size distributions are both bimodel in the day and night time. The major peaks in the day time appear in the particle diameter between 0.031-0.056 micron and 3.16-5.62 microns in the day period and appear between 0.017-0.031 micron and 1.78-3.16 microns in the night period. The results indicate that the particle size distribution in the day time tends to be of larger particle size mode than the night time.

Air Pollutants↗
PubMed1999

Epitope mapping of CCR5 reveals multiple conformational states and distinct but overlapping structures involved in chemokine and coreceptor function.

The chemokine receptor CCR5 is the major coreceptor for R5 human immunodeficiency virus type-1 strains. We mapped the epitope specificities of 18 CCR5 monoclonal antibodies (mAbs) to identify domains of CCR5 required for chemokine binding, gp120 binding, and for inducing conformational changes in Env that lead to membrane fusion. We identified mAbs that bound to N-terminal epitopes, extracellular loop 2 (ECL2) epitopes, and multidomain (MD) epitopes composed of more than one single extracellular domain. N-terminal mAbs recognized specific residues that span the first 13 amino acids of CCR5, while nearly all ECL2 mAbs recognized residues Tyr-184 to Phe-189. In addition, all MD epitopes involved ECL2, including at least residues Lys-171 and Glu-172. We found that ECL2-specific mAbs were more efficient than NH2- or MD-antibodies in blocking RANTES or MIP-1beta binding. By contrast, N-terminal mAbs blocked gp120-CCR5 binding more effectively than ECL2 mAbs. Surprisingly, ECL2 mAbs were more potent inhibitors of viral infection than N-terminal mAbs. Thus, the ability to block virus infection did not correlate with the ability to block gp120 binding. Together, these results imply that chemokines and Env bind to distinct but overlapping sites in CCR5, and suggest that the N-terminal domain of CCR5 is more important for gp120 binding while the extracellular loops are more important for inducing conformational changes in Env that lead to membrane fusion and virus infection. Measurements of individual antibody affinities coupled with kinetic analysis of equilibrium binding states also suggested that there are multiple conformational states of CCR5. A previously described mAb, 2D7, was unique in its ability to effectively block both chemokine and Env binding as well as coreceptor activity. 2D7 bound to a unique antigenic determinant in the first half of ECL2 and recognized a far greater proportion of cell surface CCR5 molecules than the other mAbs examined. Thus, the epitope recognized by 2D7 may represent a particularly attractive target for CCR5 antagonists.

Amino Acid Sequence↗