Biomedical subjects

C L Lin

Publications and source records attributed to C L Lin.

At least 37 records · Page 2Linked to original sources

PubMed2001

Assessment of donor fatty livers for liver transplantation.

AIM: The effect of fatty liver on graft survival, especially with reference to macrovesicular and microvesicular steatosis, is still uncertain. This preliminarily study was designed to create a noninvasive method for the quantification of the hepatic fat content in vivo and to establish provisional criteria for the assessment of fatty donor livers before liver transplantation among transplant surgeons, radiologists, and pathologists. METHODS AND MATERIALS: Different degrees of rat fatty liver model were established by feeding rats a diet deficient in choline and methionine for different periods of time. Computed tomography (CT) with test tubes containing variable percentages of fat equivalent substance were used to assess the severity of fatty change of the rat liver. This was then correlated with the histological classification, level of hepatic enzymes, and graft survival. RESULTS: Linear correlation between the fat volume fraction added to the test tubes and CT density were found. The process of producing a fatty liver via diet alteration peaked at week 3. At this time hepatic enzymes, radiological fat content, and posttransplantation survival were worse (P=0.013), compared with other time points. Radiological assessment of fatty liver correlated well with survival and serum glutamic oxaloacetic transaminase and glutamic pyruvate transaminase levels. CONCLUSION: Severe microvesicular steatosis does not influence recipient survival, however, macrovesicular steatosis affects graft survival. Caliber CT is a practical and simple method that allows an accurate noninvasive quantitative assessment of hepatic fatty infiltration. It has potential to be a useful parameter for the assessment of donor livers for clinical liver transplantation.

Animals↗

PubMed2001

Inhibition of melanoma growth and metastasis by combination with (-)-epigallocatechin-3-gallate and dacarbazine in mice.

(-)-Epigallocatechin-3-gallate (EGCG), a major polyphenol in green tea, was shown to have cancer chemopreventive activity. In this study, we examined the antimetastatic effects of EGCG or the combination of EGCG and dacarbazine on B16-F3m melanoma cells in vitro and in vivo. First, the antimetastatic potentials of five green tea catechins were examined by soft agar colony formation assay, and the results show that EGCG was more effective than the other catechins in inhibiting soft agar colony formation. Second, EGCG dose-dependently inhibited B16-F3m cell migration and invasion by in vitro Transwell assay. Third, EGCG significantly inhibited the spread of B16-F3m cells on fibronectin, laminin, collagen, and Matrigel in a dose-dependent manner. In addition, EGCG significantly inhibited the tyrosine phosphorylation of focal adhesion kinase (FAK) and the activity of matrix metalloproteinase-9 (MMP-9). In animal experiments, EGCG alone reduced lung metastases in mice bearing B16-F3m melanomas. However, a combination of EGCG and dacarbazine was more effective than EGCG alone in reducing the number of pulmonary metastases and primary tumor growths, and increased the survival rate of melanoma-bearing mice. These results demonstrate that combination treatment with EGCG and dacarbazine strongly inhibits melanoma growth and metastasis, and the action mechanisms of EGCG are associated with the inhibition of cell spreading, cell-extracellular matrix and cell-cell interactions, MMP-9 and FAK activities.

Animals↗

PubMed2001

IRF-1-mediated CAS expression enhances interferon-gamma-induced apoptosis of HT-29 colon adenocarcinoma cells.

The expression of CAS is reported to be upregulated in a variety of human tumor cells, and such expression correlates with the development of tumors. CAS also plays a role in apoptosis. We investigated whether CAS expression affects the susceptibility of tumor cells to IFN-gamma-induced apoptosis. Our data show that IFN-gamma treatment induces CAS expression in HT-29 tumor cells. IFN-gamma-induced gene expression is primarily mediated by the transcriptional factor, IRF-1. Our data show that IRF-1 mediates IFN-gamma-induced CAS expression. Transfection of HT-29 cells with CAS expression vector did not induce apoptosis of cells; nevertheless, CAS overexpression greatly enhanced IFN-gamma-induced apoptosis of cells. CPP32 is regarded as one of the central apoptosis executioner molecules. CAS overexpression enhances IFN-gamma-induced CPP32 expression. These results indicate that tumor cells highly expressing CAS may be more susceptible to apoptosis induced by reagents that are capable of inducing CAS expression. Thus, CAS may be a target for the elimination of tumors.

Apoptosis↗

PubMed2001

Identification of two down-regulated genes in rat liver allografts by mRNA differential display.

Total RNA differential display (DD) using random primers was performed for rat orthotopic liver transplantation (OLT) models. DA (RT1a) donor livers were transplanted into DA, PVG (RT1c), and LEW (RT1l) recipients: (1) syngeneic OLT (DA-DA): no rejection occurs; (2) allogeneic OLT (DA-PVG): rejection occurs, but is naturally overcome without immunosuppression; (3) allogeneic OLT (DA-LEW): animals die of acute rejection within 14 days. cDNA was isolated from selected bands, re-amplified for sequencing, and confirmed by Northern blots. Two down-regulated genes were observed in day-7 allogeneic OLT livers (DA-PVG, DA-LEW), while they were consistently expressed in day-7 syngeneic OLT (DA-DA) livers. These two genes were identified as alpha-glutathione sulfotransferase (alpha-GST) Ya gene and estrogen sulfotransferase (EST), respectively. Northern blots confirmed that their expression was down-regulated in OLT (DA-PVG) livers on days 7-26 and gradually restored. The mRNA expression of GST and EST may be good markers to predict rejection or induction of tolerance.

Animals↗

PubMed2001

Vascular dilatory functions of ovo-lactovegetarians compared with omnivores.

Vegetarians have lower blood pressure and lower cardiovascular mortality. Vegetarian diets may have lower cardiovascular risks through positive influence on endothelium-dependent relaxation and related functions. The objectives of this study were to assess the differences of vascular dilatory functions between middle-aged vegetarians and sex and age-matched omnivores before they develop any clinical manifestations of atherosclerosis. Twenty healthy vegetarians over the age of 50 and 20 healthy omnivores over the age of 50 were recruited for this study. Subjects with known risk factors for atherosclerosis such as hypertension, diabetes, obesity, hypercholesteremia, cigarette smoking, family history of vascular diseases, or taking any regular medication were excluded. Medical history, body weight, height, and duration of vegetarian diet were recorded. Baseline CBC, urinalysis and biochemical data such as fasting blood glucose, thyroid function, blood urea nitrogen, creatinine, serum electrolytes (sodium, potassium, chloride, calcium and magnesium), lipid profiles [total cholesterol, triglycerides, high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol] were obtained after a 14 h fast. Blood pressures and heart rate were recorded in supine position. Vascular dilatory functions, both flow-mediated (endothelium-dependent) and nitroglycerin-induced (endothelium-independent), were evaluated by using a non-invasive ultrasonographic method. The results show that there were no significant differences in the baseline characteristic between the vegetarians and the omnivores. There were also no significant differences in serum glucose, lipid profiles and thyroid function between these two groups. However, vasodilatation responses (both flow-mediated and nitroglycerin-induced) were significantly better in the vegetarian group and the degree of vasodilatation appeared to be correlated with years on vegetarian diets. Our findings suggest that vegetarian diets, by themselves, have a direct beneficial effect on vascular endothelial and smooth muscle function and may help to account for the lower incidence of atherosclerosis and cardiovascular mortality.

Blood Flow Velocity↗

PubMed2001

Prevention of cerebral vasospasm by a capsaicin derivative, glyceryl nonivamide, in an experimental model of subarachnoid hemorrhage.

BACKGROUND: Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) remains a major complication in patients suffering from SAH. In our previous study, we reported that stimulating vascular K(+) channel activity prevented the development of cerebral vasospasm. Recent evidence indicates that glyceryl nonivamide (GLNVA), a capsaicin derivative, has a vasorelaxant effect on the aortic vascular smooth muscle due to the release of coronary calcitonin gene-related peptide, which in turn stimulates K(+) channel opening. The purpose of the present study was to examine the preventive effects of GLNVA on vasospasm. METHODS: New Zealand white rabbits were subjected to experimental SAH by injecting autologous blood into the cisterna magna. GLNVA or vehicle was injected intrathecally immediately after the induction of SAH. All animals were killed by perfusion-fixation at 48 hours after SAH. The basilar arteries were removed and sectioned, and their cross-sectional areas were measured. RESULTS: The average cross-sectional areas of basilar arteries were reduced by 69% and 71% in the SAH only and SAH plus vehicle groups, respectively, when compared with the healthy controls. After treatment with 0.35, 1.75, and 3.5 mg/kg GLNVA in rabbits subjected to SAH the average cross-sectional area was decreased by 46%, 12% and 2%, respectively, when compared with the healthy controls. The protective effect of GLNVA achieved statistical significance at all dosages. Morphologically, corrugation of the internal elastic lamina of vessels was often observed in the vehicle-treated group, but was not prominent in the GLNVA-treated groups or healthy controls. CONCLUSION: The findings showed that GLNVA dose-dependently attenuated cerebral vasospasm after SAH in the rabbit. These results suggest that intrathecal administration of GLNVA could be an effective strategy for preventing cerebral vasospasm after SAH.

Animals↗

PubMed2001

Numerical investigation of the factors affecting interfacial stresses in an MOD restored tooth by auto-meshed finite element method.

Many researches have addressed the high correlation between the fracture of restored teeth and the prepared cavity geometry. In addition, concerns about bonding versus debonding dental materials from cavity walls and different occlusal force conditions could also alter the mechanical responses in a restored tooth. This study employed an automatic mesh procedure to investigate the mechanical interactions between different interfacial conditions and cavity parameters such as pulpal wall depth under different chewing functions. The results indicated that when occlusal force was applied directly on the tooth, it could increase unfavourable stress dramatically. When interfacial fixation was simulated as the contact condition between the tooth tissue and restorative material, it might increase the fracture potential exponentially compared with the bonded interface. For pulpal wall depth analyses, greater risks of fracture for the remaining tooth were observed in deeper cavity of mesio-occlusal-distal (MOD) restorations and the existence of a pulpal wall is essential even it is only 1 mm above the gingival wall.

Bite Force↗

PubMed2001

Multifactorial analysis of an MOD restored human premolar using auto-mesh finite element approach.

The use of an mesial-occlusal-distal (MOD) restoration in repairing a large carious lesion depends on many factors. Biomechanical performance is one of the most important. It has been recognized that resistance to restoration failure is not solely a biological concern (e.g. toxicity), but that the cavity shape, dimensions, and the state of stress must all be taken into account. In the present study, a newly developed auto-mesh program was used to generate 30 three-dimensional (3D) finite element (FE) models simulating the biomechanics for multiple factorial design of the MOD gold restoration in a maxillary second premolar. Stress levels were related to individual design factors (e.g. pulpal wall depth [P], isthmus width [W] and interaxial thickness [T]) and to their interactions under the worst physiological scenario: a concentrated bite force acting on lingual cusp with debonded interfaces between cavity walls and restorations. The results showed that enlarging the volume of the MOD cavity significantly increased stresses in enamel but did not intentionally affect stresses in dentin. The alternation of individual design parameters significantly changed the peak stresses (P < 0.05). For all three parameters, except for the width, the peak stress increased as the cavity dimension increased. Stress elevation rate (termed as 'volumetric stress rate'--stress elevation by increasing one unit volume of the restored materials) was different among three design factors. Depth was the most critical factor governing the stress elevation in enamel (1.76 MPa mm(-3)) while length (interaxial thickness) was the most important parameter in dentin (0.49 MPa mm(-3)). Width was the least compromising factor to the remaining tooth, 0.32 MPa mm(-3) for enamel and -0.23 MPa mm(-3) for dentin. The findings, at its core, did not fully agree with the traditional concept that the preservation of tooth substances will reduce risk of tooth fracture. This study leaves open possibility for the structural optimization of the MOD restoration.

Bicuspid↗

PubMed2001

Preoperative and postoperative seizures in patients with astrocytic tumours: analysis of incidence and influencing factors.

To evaluate the incidence and influencing factors related to preoperative and postoperative seizures, a retrospective analysis was performed in 190 patients with astrocytic tumours. Preoperative seizures occurred in 50 (26%) patients and 27 (54%) of the m had recurrent seizures. Late-onset seizures developed after craniotomy in 11 (8%) of 140 patients. Seizures at presentation were significantly correlated with age at diagnosis (P=0.0204) and pathological grade of tumour (P=0.0040). The patients aged less than 40 years had a high risk of seizures at presentation (odds ratio=3.076, P=0.0134). Postoperative seizures were significantly associated with the presence of preoperative seizures (P<0.0001), type or duration of preoperative seizures (P<0.0001, P<0.0001, respectively) and serum level of anticonvulsant drug (P=0.0068). However, only the presence of preoperative seizures had a potential for prediction of postoperative seizures when evaluated by logistic regression model (odds ratio=20.859, P=0.0001). Fifty-nine percent of patients with recurrent seizures and 64% of patients with late-onset seizures had seizures which occurred within 6 months after craniotomy. Despite therapeutic anticonvulsant levels, most postoperative seizures were associated with tumour recurrence or haemorrhage. Postoperative seizures commonly occurred relatively soon after craniotomy and prophylactic anticonvulsants should be given. In patients with postoperative seizures, particularly in the presence of therapeutic anticonvulsant level, brain computed tomography should be performed to exclude tumour recurrence or haemorrhage.

Adolescent↗

PubMed2001

The capture of heavy metals from incineration using a spray dryer integrated with a fabric filter using various additives.

This study investigated the effects of feedstock additives [polyvinyl chloride (PVC) and NaCl] and spray dryer additives (SiO2, CaCl2, NaHCO3) on heavy metal and fly ash removal efficiencies, and on particle size distribution of heavy metals. A spray dryer with an integrated fabric filter was used as an air pollution control device (APCD). Removal efficiencies for fly ash and heavy metals were greater than 95 and 90%, respectively. When additives of PVC or NaCl were used, the concentration of heavy metals distributed in fly ash apparently varied when the particle diameter was <1 microm. Although the effects of the additives SiO2, CaCl2, and NaHCO3 on the elemental size distribution of Cr were insignificant, these additives did slightly increase concentrations of Cd, Zn, and Pb partitioning in coarser particles (>1 microm).

Air Pollutants↗

PubMed2001

Clinical improvement by increased frequency of on-line hemodialfiltration.

BACKGROUND/AIMS: In spite of the better efficiency of on-line hemodiafiltration (HDF) compared with conventional hemodialysis (HD), it is relatively expensive. The aim of this study was to assess the advantages in the biochemical, hemodynamic and clinical effects in uremic patients treated with on-line HDF and with different frequencies of combination high-flux HD. METHODS: One hundred eleven patients were divided into four groups receiving different frequencies of on-line HDF (thrice, twice, once per week) and high-flux HD. RESULTS: Hemodynamic parameters including maximum drop of systolic blood pressure, episodes of symptomatic hypotension and mean saline infusion volumes during dialysis were reduced when frequencies of on-line HDF were increased. Significant improvements in urea kinetic were observed when frequencies of on-line HDF were increased. On-line HDF significantly reduced the amount of erythropoietin needed and improved intra- and inter-dialysis symptoms, physical well-being, menstruation and skin pigmentation when frequency of HDF is increased to three time per week. CONCLUSION: On-line HDF offers a better cardiovascular stability and clinical improvement. Thrice weekly on-line HDF offers a significant benefit when compared with lower frequencies of HDF per week and high-flux HD.

Female↗

PubMed2001

An enormous abdominal mass associated with acute renal failure.

We report a 67-year-old man with acute uric acid nephropathy, secondary to spontaneous tumor lysis syndrome, that presented itself as a huge intra-abdominal tumor that led to acute renal failure, hyperuricemia, and azotemia. Initial finding of hydronephrosis detected by ultrasonography led us to believe that the azotemia and decreasing amount of urine resulted from obstructive uropathy, a common complication of malignancy, caused by either a direct renal invasion or a urinary outflow tract compression because of a tumor mass effect. However, clinical observations and the response to therapeutic intervention confirmed the diagnosis of spontaneous tumor lysis syndrome, which is a rare cause of acute uric acid nephropathy.

Abdominal Neoplasms↗

PubMed2001

Continuous intravenous infusion of CGS 26303, an endothelin-converting enzyme inhibitor, prevents and reverses cerebral vasospasm after experimental subarachnoid hemorrhage.

OBJECTIVE: Endothelin-mediated vasoconstriction has been implicated in the pathophysiology of cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). Endothelin-1, the most potent vasoconstrictor peptide of the endothelin family, is synthesized initially as a large prepropeptide that requires multiple steps of post-translational processing for activation. The final step of this processing involves the proteolytic cleavage of a relatively inactive precursor, big endothelin-1, by the metalloprotease endothelin-converting enzyme. Previous findings have demonstrated that intravenous bolus injections of an endothelin-converting enzyme inhibitor (CGS 26303) administered twice daily can prevent and reverse arterial narrowing in a rabbit model of SAH. However, attenuation of vasospastic response was incomplete and required relatively high doses to be effective in reversing vasospasm. Therefore, the present study evaluated an alternative protocol for administration of CGS 26303 to optimize the antispastic influence of this compound. METHODS: Continuous intravenous infusion of CGS 26303 at doses of 2.4, 8.0, or 24.0 mg/kg/d was initiated either 1 hour (prevention paradigm) or 24 hours (reversal paradigm) after experimental SAH in New Zealand White rabbits. All animals were killed by perfusion-fixation 48 hours after SAH. Basilar arteries were then removed and sectioned, and their cross-sectional areas were measured by use of computer-assisted video microscopy. RESULTS: Continuous intravenous infusion of CGS 26303 attenuated SAH-induced cerebral vasospasm in a dose-dependent manner in both the prevention and the reversal groups. These effects achieved statistical significance at all doses as compared with the SAH-only or SAH-plus-vehicle groups. Furthermore, the attenuation of vasospasm after continuous infusion of CGS 26303 was more efficacious than that obtained with bolus injections. CONCLUSION: These findings provide further support for the use of endothelin-converting enzyme inhibition as a therapeutic strategy for reduction of cerebral vasospasm, and they also support the effectiveness of this strategy even when initiated after arterial narrowing has been established. The findings also indicate that continuous intravenous infusion of CGS 26303 is a more effective approach for attenuation of vasospasm than bolus intravenous administration.

Animals↗

PubMed2001

Long-term on-line hemodiafiltration reduces predialysis beta-2-microglobulin levels in chronic hemodialysis patients.

BACKGROUND: Hemodiafiltration (HDF) is effective in delaying the surgical need for carpal tunnel syndrome in chronic hemodialysis patients, however, predialysis beta(2)-microglobulin levels were not reduced in most short-term studies. The aim of this study was to assess the effect of long-term and differing frequencies of on-line HDF on serum beta(2)-microglobulin levels in comparison to high-flux hemodialysis (HD). METHODS: One hundred and twelve patients in the Chang Gung Memorial Hospital Dialysis Unit were divided into three groups to receive different frequencies of on-line HDF alternating with high-flux HD. Group 1 was treated once with HDF and twice with high-flux HD per week (n = 21). Group 2 was treated twice with HDF and once with high-flux HD per week (n = 33). Group 3 was treated with HDF three times per week (n = 58). Analysis was performed to compare the serum beta(2)-microglobulin levels in these groups and to high-flux HD. RESULTS: After receiving HDF for a mean of 7.9 months, group 3 patients had a reduced predialysis beta(2)-microglobulin level (22.2 +/-5.3 vs. 34.8 +/-6.3 mg/l, p < 0.001), postdialysis beta(2)-microglobulin level (6.3 +/- 2.0 vs. 13.8 +/- 6.8 mg/l, p < 0.001) and an increased beta(2)-microglobulin reduction rate (76.1 +/- 5.6 vs. 61.1 +/- 13.3%, p = 0.03) when compared to high-flux HD. A significant improvement in URR (p = 0.0004), Kt/V (p = 0.0002) and TAC urea levels (p = 0.006) but not nPCR (p = 0.122) was found after patients had been treated with on-line HDF. The beta(2)-microglobulin reduction rate was positively correlated with the overall volume of the replacement solution per session (p < 0.0001). Patients in group 3 had lower predialysis beta(2)-microglobulin levels than those in group 1 and group 2 (22.2 +/- 5.3 vs. 25.2 +/- 7.2 vs. 26.0 +/- 4.2 mg/l, p = 0.02). Furthermore, an inverse correlation was found between the predialysis beta(2)-microglobulin level and the duration of HDF, if patients were treated for more than 12 months (p = 0.031). CONCLUSION: On-line HDF has an increased dialysis efficiency compared to high-flux dialysis. Long-term HDF further reduced predialysis beta(2)-microglobulin levels, thus, it may provide an improved modality for renal replacement therapy.

Adult↗

PubMed2001

[Effect of combination of ligustrazine and nitrendipine on hemodynamics in patients with chronic obstructive pulmonary disease].

OBJECTIVE: To find the drugs for lowering the pulmonary vascular resistance in patients of chronic obstructive pulmonary disease (COPD) but would not increase its side-effect. METHODS: Changes of some hemodynamic parameters in 15 patients of COPD in stable stage treated by nitrendipine and ligustrazine were observed by right heart floating catheterization. RESULTS: The mean pulmonary arterial pressure reduced by 1.4% immediately after the combined treatment, and reduced by 17.0%, 20.0% and 18.0% in 15 mins, 30 mins and 60 mins after treatment. In the responding time, the pulmonary vascular resistance reduced by 15.2%, 36.2%, 43.0% and 34.6%, the systemic vascular resistance reduced by 7.9%, 19.2%, 17.9% and 20.8%, and the cardiac output increased by 15.8%, 22.6%, 22.2%, and 33.8% respectively. The changes of systemic arterial pressure and heart rate were of no statistical significance. CONCLUSION: Combination therapy of nitrendipine and ligustrazine could lower the pulmonary arterial pressure and pulmonary vascular resistance effectively and has a selective effect on pulmonary circulation in patients with COPD.

Adult↗

PubMed2001

[Therapeutic mechanism of combination therapy of ligustrazine and nitrendipine in treating patients with chronic obstructive pulmonary disease].

OBJECTIVE: To study the therapeutic mechanism of combination therapy of ligustrazine and nitrendipine in treating patients with chronic obstructive pulmonary disease (COPD). METHODS: Thirty COPD patients divided in to 3 groups (10 in each) were treated with ligustrazine, nitrendipine and ligustrazine plus nitrendipine respectively, and the changes of hemorrheologic parameters, plasma endothelin (ET-1), thromboxane A2(TXA2) and platelet-P-selectin (CD62P) before and after treatment were observed. RESULTS: The combination therapy of ligustrazine and nitrendipine could lower the levels of plasma ET-1, TXA2, CD62P and the hemorrheologic parameters. CONCLUSION: Combination of ligustrazine and nitrendipine showed a therapeutic effect better than that of the two drugs used separately. Its effect in lowering pulmonary circulation resistance is related with the lowering of plasma vaso-contrictive factor and the changing of hemorrheologic properties. The integrated traditional Chinese and western medical therapy is valuable in treating COPD.

Aged↗

PubMed2000

Macrophage-tropic HIV induces and exploits dendritic cell chemotaxis.

Immature dendritic cells (iDCs) express the CC chemokine receptor (CCR)5, which promotes chemotaxis toward the CC chemokines regulated on activation, normal T cell expressed and secreted (RANTES), macrophage inflammatory protein (MIP)-1alpha, and MIP-1beta. By contrast, mature DCs downregulate CCR5 but upregulate CXC chemokine receptor (CXCR)4, and as a result exhibit enhanced chemotaxis toward stromal cell-derived factor (SDF)-1alpha. CCR5 and CXCR4 also function as coreceptors for macrophage-tropic (M-tropic) and T cell-tropic (T-tropic) human immunodeficiency virus (HIV)-1, respectively. Here, we demonstrate chemotaxis of iDCs toward M-tropic (R5) but not T-tropic (X4) HIV-1. Furthermore, preexposure to M-tropic HIV-1 or its recombinant envelope protein prevents migration toward CCR5 ligands. The migration of iDCs toward M-tropic HIV-1 may enhance formation of DC-T cell syncytia, thus promoting viral production and destruction of both DC and T helper lymphocytes. Therefore, disturbance of DC chemotaxis by HIV-1 is likely to contribute to immunosuppression in primary infection and AIDS. In addition, migration of iDCs toward HIV-1 may aid the capture of R5 HIV-1 virions by the abundant DC cell surface protein DC-specific intercellular adhesion molecule (ICAM)3-grabbing nonintegrin (DC-SIGN). HIV-1 bound to DC cell-specific DC-SIGN retains the ability to infect replication-permissive T cells in trans for several days. Consequently, recruitment of DC by HIV-1 could combine with the ability of DC-SIGN to capture and transmit the virus to T cells, and so facilitate dissemination of virus within an infected individual.

Animals↗

PubMed2000

Binding of retinol induces changes in rat cellular retinol-binding protein II conformation and backbone dynamics.

The structure and backbone dynamics of rat holo cellular retinol-binding protein II (holo-CRBP II) in solution has been determined by multidimensional NMR. The final structure ensemble was based on 3980 distance and 30 dihedral angle restraints, and was calculated using metric matrix distance geometry with pairwise Gaussian metrization followed by simulated annealing. The average RMS deviation of the backbone atoms for the final 25 structures relative to their mean coordinates is 0.85(+/-0.09) A. Comparison of the solution structure of holo-CRBP II with apo-CRBP II indicates that the protein undergoes conformational changes not previously observed in crystalline CRBP II, affecting residues 28-35 of the helix-turn-helix, residues 37-38 of the subsequent linker, as well as the beta-hairpin C-D, E-F and G-H loops. The bound retinol is completely buried inside the binding cavity and oriented as in the crystal structure. The order parameters derived from the (15)N T(1), T(2) and steady-state NOE parameters show that the backbone dynamics of holo-CRBP II is restricted throughout the polypeptide. The T(2) derived apparent backbone exchange rate and amide (1)H exchange rate both indicate that the microsecond to second timescale conformational exchange occurring in the portal region of the apo form has been suppressed in the holo form.

Amides↗