Biomedical subjects

J Chen

Publications and source records attributed to J Chen.

At least 883 records · Page 49Linked to original sources

PubMed2000

Interstitial fibrosis of unilateral ureteral obstruction is exacerbated in kidneys of mice lacking the gene for inducible nitric oxide synthase.

Unilateral ureteral obstruction (UUO) is characterized by decreases in renal function and increases in interstitial fibrosis. Previous studies have indicated that pharmacologic manipulations that increase nitric oxide (NO) are beneficial to the obstructed kidneys. NO is produced from arginine by nitric oxide synthase (NOS), an enzyme that exists in both constitutive and inducible (iNOS) forms. To determine the role of the inducible form of NOS in UUO, we used mice with a targeted deletion of iNOS (iNOS -/- mice) and compared them with wild-type (WT) mice. Kidneys were obstructed for 2 weeks in both WT and iNOS -/- mice, and were then removed and bisected. Half of the kidney was embedded in paraffin and tissue sections were examined for interstitial volume or the presence of macrophages. The remainder was flash-frozen and samples were used to measure tissue collagen (hydroxyproline) or transforming growth factor-beta (TGF-beta). This study demonstrates that both cortex and medulla of obstructed kidneys of iNOS -/- mice exhibit significantly increased interstitial volume and interstitial macrophages as compared with their WT counterparts. Furthermore tissue collagen was increased to 9.2+/-1.3 microg/mg tissue in WT obstructed kidneys, whereas in iNOS -/- kidneys, collagen was increased to 13.2+/-0.8 microg/mg tissue. The profibrotic cytokine TGF-beta was also significantly increased in obstructed kidneys of iNOS -/- mice, as compared with WT mice. No differences were noted between the unobstructed kidneys of iNOS -/- mice compared with WT mice in any of the parameters examined. These results demonstrate that targeted deletion of the iNOS results in exacerbation of fibrotic events in the obstructed kidney. These results confirm previous pharmacologic studies, and suggest that NO produced via the inducible NOS normally serves a protective function in UUO.

Animals↗

PubMed2000

Replacement of the carboxylic acid group of prostaglandin f(2alpha) with a hydroxyl or methoxy substituent provides biologically unique compounds.

Replacement of the carboxylic acid group of PGF(2alpha) with the non-acidic substituents hydroxyl (-OH) or methoxy (-OCH(3)) resulted in an unexpected activity profile. Although PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) exhibited potent contractile effects similar to 17-phenyl PGF(2alpha) in the cat lung parenchymal preparation, they were approximately 1000 times less potent than 17-phenyl PGF(2alpha) in stimulating recombinant feline and human FP receptors. In human dermal fibroblasts and Swiss 3T3 cells PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) produced no Ca(2+) signal until a 1 microM concentration was exceeded. Pretreatment of Swiss 3T3 cells with either 1 microM PGF(2alpha) 1-OH or PGF(2alpha) 1-OCH(3) did not attenuate Ca(2+) signal responses produced by PGF(2alpha) or fluprostenol. In the rat uterus, PGF(2alpha) 1-OH was about two orders of magnitude less potent than 17-phenyl PGF(2alpha) whereas PGF(2alpha) 1-OCH(3) produced only a minimal effect. Radioligand binding studies on cat lung parenchymal plasma membrane preparations suggested that the cat lung parenchyma does not contain a homogeneous population of receptors that equally respond to PGF(2alpha)1-OH, PGF(2alpha)1-OCH(3), and classical FP receptor agonists. Studies on smooth muscle preparations and cells containing DP, EP(1), EP(2), EP(3), EP(4), IP, and TP receptors indicated that the activity of PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) could not be ascribed to interaction with these receptors. The potent effects of PGF(2alpha) 1-OH and PGF(2alpha) 1-OCH(3) on the cat lung parenchyma are difficult to describe in terms of interaction with the FP or any other known prostanoid receptor.

3T3 Cells↗

PubMed2000

Human mu-opioid receptor overexpressed in Sf9 insect cells functionally coupled to endogenous Gi/o proteins.

Human mu-opioid receptor (HmuOR) with a tag of six consecutive histidines at its carboxyl terminus had been expressed in recombinant baculovirus infected Sf9 insect cells. The maximal binding capacity for the [3H] diprenorphine and [3H]ohmefentanyl (Ohm) were 9.1 +/- 0.7 and 6.52 +/- 0.23 nmol/g protein, respectively. The [3H] diprenorphine or [3H] Ohm binding to the receptor expressed in Sf9 cells was strongly inhibited by mu-selective agonists [D-Ala2, N-methyl-Phe4, glyol5]enkephalin (DAGO), Ohm, and morphine, but neither by delta nor by kappa selective agonist. Na+ (100 mM) and GTP (50 microM) could reduce HmuOR agonists etorphine and Ohm affinity binding to the overexpressed HmuOR. mu-selective agonists DAGO and Ohm effectively stimulated [35S]GTP-gammaS binding (EC50 = 2.7 nM and 6.9 nM) and inhibited forskolin- stimulated cAMP accumulation (IC50 = 0.9 nM and 0.3 nM). The agonist-dependent effects could be blocked by opioid antagonist naloxone or by pretreatment of cells with pertussis toxin (PTX). These results demonstrated that HmuOR overexpressed in Sf9 insect cells functionally coupled to endogenous G(i/o) proteins.

Animals↗

PubMed2000

The value of testing pudendal nerve conduction in evaluating erectile dysfunction in diabetics.

We conducted an open prospective study on the value of testing pudendal nerve conduction (PNC) in 45 diabetic and 32 nondiabetic men with documented erectile dysfunction (ED) of at least six months duration. All subjects underwent PNC by the same investigator using the Medcelec/TECA Sapphire device with calibration parameters of sweep 10 ms/div an amplitude of 200 microV/div. No statistically significant differences was found in the mean bulbocavernosus reflex (BCR) latencies between the nondiabetics (33.6 ms/div +/- 4.1) and the diabetics (37.5 ms/div +/- 9.1) (P > 0.05). Our results show that electrophysiological measurement of the BCR in diabetics is not a useful diagnostic test and emphasize the importance of a multifactorial evaluation of diabetic ED.

Adult↗

PubMed2000

Predicting penile size during erection.

The aim of this prospective study was to identify clinical and engineering parameters of the flaccid penis for prediction of penile size during erection. Dorsal and ventral penile lengths, as well as base and tip circumferences were measured in flaccid states, gently stretched states and at full erection resulting from intracavernosal injection of prostaglandin E1 in 55 patients. The forces required to stretch the penis were measured by a specially designed gauge and regression relationships of the measured dimensions were calculated. An engineering model was developed to analyze differences between results obtained during stretching and erection, as well as to approximate the optimal force values which should be applied during the stretching part of the clinical evaluation of penile size. The ratio between the flaccid to stretched penile lengths was shown to be the best predictor for the ventral elongation from flaccid to erect penile lengths. The engineering analysis predicted that a minimal tension force of approximately 450 g during stretching of the penis is required to reach the potential erection length. The stretching forces exerted by the urologist in the clinical setting were experimentally shown to be significantly (P<0.01) less than this value. The values of the relative and absolute elongations of the stretched penis at its ventral aspect provide reliable estimations of its potential maximal elongation during erection. The model designed for this study may obviate the use of intracavernosal injections for estimating penile length during erection.

Adult↗

PubMed2000

Effects of T-loop geometry on its forces and moments.

The moments and forces produced by various orthodontic T-loop spring designs were measured. The effects of dimension changes (within clinically used ranges) and the addition of gable bends with heat treatment were assessed. Increasing the vertical or horizontal dimension reduced the spring's load-deflection rate and its moment-to-force ratio. Gable preactivation with heat treatment had the opposite effects.

Analysis of Variance↗

PubMed2000

Splenectomy in haemophagocytic lymphohistiocytosis: report of histopathological changes with CD19+ B-cell depletion and therapeutic results.

The pathogenesis of haemophagocytic lymphohistiocytosis (HLH) in children without a known familial pattern of inheritance is often difficult to establish. Splenic enlargement, one of the main clinical findings in this disorder, has led to the use of splenectomy for uncontrollable coagulopathy, persistent cytopenia or both. This procedure is also thought to be a useful tool in making a differential diagnosis in cases of the immunochemotherapy-resistant HLH. We report here five cases of splenectomized childhood HLH, in which subsets of mononuclear spleen cells were analysed either by flow cytometry or immunohistochemistry, and the results were compared with those from cases of hereditary spherocytosis (controls). There was a statistically significant depletion of CD19+ B cells in the HLH cases (3.8 +/- 3.2% vs. 52.6 +/- 4.5%, P < 0. 0001) associated with an increase of T cells in three cases and of natural killer cells in another. The histopathological findings included atrophic white pulps, B-cell depletion with fibrosis and haemosiderosis in all five cases. Despite temporary therapeutic benefits, three of the HLH patients had a rapidly deteriorating post-splenectomy course and all three eventually died. These results demonstrate striking depletion of B cells in the enlarged spleens of children with HLH, which may be an intrinsic feature of HLH pathogenesis. Further study is needed to establish the therapeutic value of splenectomy in this disease.

Antigens, CD19↗

PubMed2000

Possible biphasic changes of free radicals in ethylene glycol-induced nephrolithiasis in rats.

OBJECTIVE: To evaluate the possible role of free radicals in nephrolithiasis in rats induced by ethylene glycol, and to examine the correlation between the urinary enzymes N-acetyl-beta-glucosaminidase (NAG), beta-galactosidase (GAL) and neutral endopeptidase (NEP), and free radical production. MATERIALS AND METHODS: Hyperoxaluria was produced in male Wistar rats by adding ethylene glycol to their drinking water. After 7, 21 and 42 days of treatment, urinary oxalate, creatinine clearance and urinary enzymes (NAG, GAL and NEP) were measured. The nitroblue tetrazolium perfusion method was used to locate the sites of free-radical production. Ultrasensitive chemiluminescence was used to directly measure the production of reactive oxygen species (ROS) in vivo. Vitamin E and potassium citrate were fed to rats, in addition to ethylene glycol, to assess their effects on free radical production. RESULTS: Urinary oxalate increased significantly and was associated with an increase in NAG and GAL at all sample times. However, urinary NEP activity was unchanged on day 7, although there was four times as much NEP on days 21 and 42 than in the control groups. Formazan particles in the renal cortex were scored as 3+ to 4+ in rats treated for 7 days with ethylene glycol. Blood ROS levels were also higher in this group than in the controls (P < 0.01). After vitamin E and potassium citrate treatment, blood ROS levels were lower than in rats treated with ethylene glycol alone. CONCLUSION: Free radicals may be produced in the early stages of nephrolithiasis in rats fed with ethylene glycol. Free radicals occurred mainly in blood and might be associated with NEP inactivation.

Animals↗

PubMed2000

Formation of the base modification 8-hydroxyl-2'-deoxyguanosine and DNA fragmentation following seizures induced by systemic kainic acid in the rat.

The formation of oxidative DNA damage as a consequence of seizures remains little explored. We therefore investigated the regional and temporal profile of 8-hydroxyl-2'-deoxyguanosine (8-OHdG) formation, a hallmark of oxidative DNA damage and DNA fragmentation in rat brain following seizures induced by systemic kainic acid (KA). Formation of 8-OHdG was determined via HPLC with electrochemical detection, and single- and double-stranded DNA breaks were detected using in situ DNA polymerase I-mediated biotin-dATP nick-translation (PANT) and terminal deoxynucleotidyl-transferase-mediated nick end-labeling (TUNEL), respectively. Systemic KA (11 mg/kg) significantly increased levels of 8-OHdG within the thalamus after 2 h, within the amygdala/piriform cortex after 4 h, and within the hippocampus after 8 h. Levels remained elevated up to sevenfold within these areas for 72 h. Smaller increases in 8-OHdG levels were also detected within the parietal cortex and striatum. PANT-positive cells were detected within the thalamus, amygdala/piriform cortex, and hippocampus 24-72 h following KA injection. TUNEL-positive cells appeared within the same brain regions and over a similar time course (24-72 h) but were generally lower in number. The present data suggest oxidative damage to DNA may be an early consequence of epileptic seizures and a possible initiation event in the progression of seizure-induced injury to DNA fragmentation and cell death.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2000

Activation of poly(ADP-ribose) polymerase in the rat hippocampus may contribute to cellular recovery following sublethal transient global ischemia.

We have investigated the role of poly(ADP-ribose) polymerase (PARP) activation in rat brain in a model of sublethal transient global ischemia. Adult male rats were subjected to 15 min of ischemia with brain temperature reduced to 34 degrees C, followed by 1, 2, 4, 8, 16, 24, and 72 h of reperfusion. PARP mRNA expression was examined in the hippocampus using quantitative RT-PCR, northern blot analysis, and in situ hybridization. Protein expression was assessed using western blot analysis. PARP enzymatic activity was investigated by measuring nuclear [3H]NAD incorporation. The presence of poly(ADP-ribose) polymers was assessed immunocytochemically. Although PARP mRNA and protein expressions were not altered after ischemia, enzymatic activity was increased 4.37-fold at 1 h (p < 0.05 vs. sham) and 1.73-fold (p < 0.05 vs. sham) at 24 h of reperfusion. Immunostaining demonstrated the presence of poly(ADP-ribose) polymers in CA1 neurons. Cellular NAD+ levels were not significantly altered at any time point. Furthermore, systemic administration of 3-aminobenzamide (30 mg/kg), a PARP inhibitor, prevented the increase in PARP activity at 1 and 24 h of reperfusion, significantly decreased the number of surviving neurons in the hippocampal CA1 region 72 h after ischemia (p < 0.01 vs. sham), and increased DNA single-strand breaks assessed as DNA polymerase I-mediated biotin-dATP nick-translation (PANT)-positive cells (p < 0.01 vs. sham). Furthermore, using an in vitro DNA repair assay, 3-aminobenzamide (30 mg/kg) was shown to block DNA base excision repair activity. These data suggest that the activation of PARP, without subsequent NAD+ depletion, following mild transient ischemia may be neuroprotective in the brain.

Animals↗

PubMed2000

Induction of oxidative DNA damage in the peri-infarct region after permanent focal cerebral ischemia.

To address the role of oxidative DNA damage in focal cerebral ischemia lacking reperfusion, we investigated DNA base and strand damage in a rat model of permanent middle cerebral artery occlusion (MCAO). Contents of 8-hydroxyl-2'-deoxyguanosine (8-OHdG) and apurinic/apyrimidinic abasic sites (AP sites), hallmarks of oxidative DNA damage, were quantitatively measured in nuclear DNA extracts from brains obtained 4-72 h after MCAO. DNA single- and double-strand breaks were detected on coronal brain sections using in situ DNA polymerase I-mediated biotin-dATP nick-translation (PANT) and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL), respectively. Levels of 8-OHdG and AP sites were markedly elevated 16-72 h following MCAO in the frontal cortex, representing the peri-infarct region, but levels did not significantly change within the ischemic core regions of the caudateputamen and parietal cortex. PANT- and TUNEL-positive cells began to be detectable 4-8 h following MCAO in the caudate-putamen and parietal cortex and reached maximal levels at 72 h. PANT- and TUNEL-positive cells were also detected 16-72 h after MCAO in the lateral frontal cortex within the infarct border, where many cells also showed colocalization of DNA single-strand breaks and DNA fragmentation. In contrast, levels of PANT-positive cells alone were transiently increased (16 h after MCAO) in the medial frontal cortex, an area distant from the infarct zone. These data suggest that within peri-infarct brain regions, oxidative injury to nuclear DNA in the form of base and strand damage may be a significant and contributory cause of secondary expansion of brain damage following permanent focal ischemia.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed2000

Involvement of caspase-3-like protease in the mechanism of cell death following focally evoked limbic seizures.

The cysteine protease caspase-3 may be involved in the mechanism of cell death following seizures. Using a rat model of focally evoked limbic epilepsy with continuous electroencephalography monitoring, we investigated seizure-induced changes in caspase-3 protein expression and processing, enzyme activity, and the in vivo effect of caspase-3 inhibition. Seizures were induced by intraamygdaloid injection of kainic acid (0.1 microg) and were terminated after 45 min by diazepam (30 mg/kg) administration. Animals were killed 0-72 h following diazepam administration. Levels of the 32-kDa proenzyme form of caspase-3 were unaffected by seizures. Levels of the 17-kDa cleaved (active) fragment of caspase-3 were almost undetectable in control brain, but were increased significantly at 4 and 24 h within ipsilateral hippocampus and cortex in seizure animals. Caspase-3-like protease activity was increased within the ipsilateral hippocampus at 8 and 24 h following seizures. Caspase-3 immunoreactivity was increased within the vulnerable ipsilateral CA3/CA4 subfield at 24 and 72 h following seizures and was associated predominantly, but not exclusively, with neurons exhibiting DNA fragmentation. The putatively selective caspase-3 inhibitor N-benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethyl ketone significantly improved neuronal survival bilaterally within the hippocampal CA3/CA4 subfields following seizures. Collectively, these data suggest that caspase-3 may play a significant role in the mechanism by which neurons die following seizures.

Animals↗

PubMed2000

Antibody to transforming growth factor-beta ameliorates tubular apoptosis in unilateral ureteral obstruction.

BACKGROUND: Unilateral ureteral obstruction (UUO) is characterized by progressive renal atrophy, renal interstitial fibrosis, an increase in renal transforming growth factor-beta (TGF-beta), and renal tubular apoptosis. The present study was undertaken to determine the effect of a monoclonal antibody to TGF-beta (1D11) in UUO. METHODS: Mechanical stretch was applied to tubular epithelial cells (NRK-52E) by a computer-assisted system. Three doses of 1D11 (either 0.5, 2, or 4 mg/rat) were administered to rats one day prior to UUO and every two days thereafter, and kidneys were harvested at day 13. Fibrosis was assessed by measuring tissue hydroxyproline and mRNA for collagen and fibronectin. Apoptosis was assessed with the terminal deoxy transferase uridine triphosphate nick end-labeling assay. TGF-beta levels were determined by bioassay. Western blot and immunostaining were used to identify proliferating cell nuclear antigen (PCNA), p53, bcl-2, and inducible nitric oxide synthase (iNOS). RESULTS: Stretch significantly induced apoptosis in NRK-52E cells, which was accompanied by an increased release of TGF-beta; 1D11 (10 microg/mL) totally inhibited stretch-induced apoptosis. Control obstructed kidney contained 20-fold higher TGF-beta as compared with its unobstructed kidney; 1D11 neutralized tissue TGF-beta of the obstructed kidney. Control obstructed kidney exhibited significantly more fibrosis and tubular apoptosis than its unobstructed counterpart, which was blunted by 1D11. In contrast, 1D11 significantly increased tubular proliferation. p53 immunostaining was localized to renal tubular nuclei of control obstructed kidney and was diminished by 1D11. In contrast, bcl-2 was up-regulated in the 1D11-treated obstructed kidney. Total NOS activity and iNOS activity of the obstructed kidney were increased by 1D11 treatment. CONCLUSION: The present study strongly suggests that an antibody to TGF-beta is a promising agent to prevent renal tubular fibrosis and apoptosis in UUO.

Animals↗

PubMed2000

Efficacy of tissue plasminogen activator administration on patency of hemodialysis access catheters.

Patients with end-stage renal disease use hemodialysis catheters for either temporary or permanent blood access. Recurrent thrombosis and fibrin sheath formation are common causes of poor or inadequate blood flow rates that require intervention. We studied the effect of tissue plasminogen activator (tPA) in reestablishing adequate blood flow rates through nonfunctional vascular catheters in 22 consecutive chronic hemodialysis patients. From January 1, 1999, to May 20, 1999, there were 56 instances in which tPA was used in an attempt to improve blood flow rates. In all instances, 2 mg of tPA was infused into each port of a dual-lumen internal jugular catheter. Dwell time ranged between 2 and 96 hours (median, 24 hours), and patient follow-up ranged between 47 and 140 days (median, 133.5 days). tPA was effective in establishing adequate blood flow rates (>/=200 mL/min) during the next dialysis session in 49 of 56 cases (87.5%). Seven additional interventions were required because of early or late tPA failure (one fibrin sheath stripping, one catheter replacement for kinking, one catheter replacement for central venous stenosis, and four catheter replacements for persistently poor blood flow rates), and eight catheters were replaced for infection. Thus, further interventions to achieve adequate blood flow rates were required in 12.5% of the cases because of early or late tPA failure. tPA appears to be as effective as urokinase for reestablishing adequate blood flow rates through hemodialysis catheters that are thrombosed or have low blood flow rates.

Adult↗

PubMed2000

Impact of secondary cytoreductive surgery on survival of patients with advanced epithelial ovarian cancer.

AIMS: To investigate the impact on survival of secondary cytoreduction for advanced epithelial ovarian cancer and variables influencing redebulking surgical outcome. METHODS: Between 1986 and 1997, 106 patients who received secondary cytoreductive surgery and consequent second-line chemotherapy for stages III and IV epithelial ovarian cancer were retrospectively reviewed. The optimal residual disease cut-off was 1.0 cm. The Cox proportional regression model and logistic stepwise regression were used in statistical processing of the data. RESULTS: The median age of the patients was 50 years (range, 26-77 years). Optimal secondary cytoreduction was achieved in 46 of 106 patients (43.4%). There was a significant difference in survival between patients who were optimally cytoreduced compared to those suboptimaly cytoreduced, with an estimated median survival in the optimal group of 20 months vs 8 months in the suboptimal group ((2)=42.03, P=0.0000). When factorized, patients had significant survival benefit from optimal secondary cytoreduction for recurrent disease and interval cytoreduction. Survival was adversely influenced by progression-free interval < or =12 months (P=0.0078), residual disease >1 cm (P=0.0001) and presence of refractory ascites (P=0.0001). The probability of successful redebulking surgery was affected by presence of refractory ascites (P=0.0023) in all 106 patients and by the ascites (P=0.0072) and residual disease at initial operation in recurrent disease (P=0.0096). CONCLUSION: Secondary surgical cytoreduction surgery significantly lengthened survival for patients with recurrent epithelial ovarian cancer or those receiving interval cytoreduction. Patients with refractory ascites, however, were not suitable for aggressive secondary surgery, and redebulking surgery for those with residual disease of >1.0 cm after primary operation should be considered prudently in recurrent disease.

Adult↗

PubMed2000

Secondary heat, but not mechanical, hyperalgesia induced by subcutaneous injection of bee venom in the conscious rat: effect of systemic MK-801, a non-competitive NMDA receptor antagonist.

Subcutaneous (s.c.) administration of bee venom into the plantar surface of one hind paw in rats has been found to produce an immediate single phase of persistent spontaneous nociceptive responses (continuously flinching, licking or lifting the injected paw) for 1-2 h accompanied by a 72-96 hour period of primary heat and mechanical hyperalgesia in the injection site and a spread of heat, but not mechanical, hyperalgesia in the non-injected hind paw (Chen et al., 1999b). To gain insight into the underlying mechanisms of the bee venom-induced hyperalgesia in particular, we further identified a heat, but not mechanical, hyperalgesia in an area (paw pad) distant from the injection site induced by s.c. injection of bee venom into the posterior leg 0.8-1.2 cm proximal to the heel measured by paw withdrawal reflex to radiant heat or von Frey monofilament stimuli in conscious rats. In the bee venom-treated hind limb, however, significant reduction in both thermal latency and mechanical threshold of withdrawal reflex was identified for a period of more than 96 h in the heel with a similar characteristic to the primary heat and mechanical hyperalgesia identified in the injection site previously. The time course of the heat hyperalgesia identified in the paw pad of the bee venom-treated side was shorter and lasted for less than 48 h, which was in parallel with the reduction in thermal latency of the withdrawal reflex identified in the non-injected hind paw. Moreover, pre- or post-treatment with a single dose of MK-801 (0.01 mg/kg, i.p.), a non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist, completely blocked the occurrence, and reversed the established process of the heat hyperalgesia identified in either the bee venom-treated or non-treated paw pads, while the same treatments with the drug did not produce any influence upon the development and maintaining of the heat and mechanical hyperalgesia identified in the heel of the injected hind limb. Taken together with our previous results following s.c. intraplantar bee venom injection, we conclude that: (1) in addition to the well-identified primary heat and mechanical hyperalgesia in the injection site and its adjacent area, s.c. bee venom is also able to produce a secondary heat hyperalgesia in a region distant from the injection site which has a similar characteristic to the contralateral heat hyperalgesia; (2) NMDA receptors are involved in either development or maintenance of the secondary and the contralateral heat hyperalgesia, but without any role in those processes of the primary heat and mechanical hyperalgesia; (3) the secondary heat hyperalgesia seen in the injected hind limb is likely to share the same neural mechanisms with that identified in the non-injected side via co-activation of NMDA receptors.

Animals↗

PubMed2000

ATP depletion in rat cholangiocytes leads to marked internalization of membrane proteins.

Intrahepatic bile ducts (BD) are a critical target of injury in the postischemic liver. Decreased vascular perfusion causes characteristic changes in the morphology of the ductular epithelia including a loss of secondary membrane structures and a decrease in plasma membrane surface area. Using adenosine triphosphate (ATP) depletion of cultured normal rat cholangiocytes (NRC) to model ischemic ducts, the present studies examined the fate of apical membrane proteins to determine whether membrane recycling might contribute to rapid functional recovery. Apical proteins, including gamma-glutamyl transpeptidase (GGT), Na(+)-glucose cotransporter (SGLT1), and apically biotinylated proteins, were not shed into the luminal space during ATP depletion. Instead, labeling of surface proteins after ATP depletion showed a significant decrease in GGT and SGLT1, consistent with membrane internalization. Similarly, z-axis confocal microscopy of biotinylated apical proteins also showed protein internalization. During ATP recovery, SGLT1 transport activity remained profoundly depressed even after 24 hours of recovery, indicating that the function of the internalized apical proteins is not rapidly recovered. These studies suggest that the membrane internalization in ATP-depleted cholangiocytes is a unidirectional process that contributes to prolonged functional deficits after restoration of normal cellular ATP levels. This sustained decrease in transport capacity may contribute to the development of ductular injury in postischemic livers.

Adenosine Triphosphate↗

PubMed2000

LPS and cytokine-activated endothelium.

Endothelial cells coordinate the recruitment of inflammatory cells to sites of vascular injury. Endothelial cells produce and release cytokines and growth factors serving as communication signals to leukocytes as well as with organs and tissues. In addition, endothelial cells respond to inflammatory stimuli such as lipopolysaccharides (endotoxin, LPS), cytokines, or ligation of CD40. Functional changes in response to inflammatory stimuli are mediated by induction of signaling cascades leading to activation of transcription factors and alterations in endothelial gene expression. This article summarizes the current knowledge of molecular events resulting in cytokine-mediated endothelial dysfunction.

Apoptosis↗