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F L Chan

Publications and source records attributed to F L Chan.

At least 37 records · Page 2Linked to original sources
PubMed2001

Rodent PSP94 gene expression is more specific to the dorsolateral prostate and less sensitive to androgen ablation than probasin.

To date, the rodent ventral prostate (VP) has been the focus of many studies on androgen action, less attention has been directed to the lateral prostate (LP) and the dorsal prostate (DP). The rodent VP has no clear homologous counterpart in the human prostate. The rodent LP and DP is the only prostate lobe comparable to the peripheral zone of the human prostate, where hormone-induced prostate cancer mainly occurs. To explore its utility for prostate targeting, we have studied the gene expression of PSP94 with rat probasin (rPB), a gene commonly used for prostate targeting in prostate cancer research and a gene typically responsive to androgen regulation. Firstly, we demonstrated PSP94 gene transcription being more specific to the LP and DP lobes than rPB, where rPB RNA was detected in the LP and DP and other lobes at different levels. Secondly, we found that PSP94 gene transcription decreased relatively slowly in response to androgen deprivation but recovered rapidly in response to testosterone replacement after complete ablation of PSP94 transcription. In the VP, gene transcripts of rPB were specifically responsive to androgen deprivation; however, they responded relatively slowly in the LP and DP. RNase protection experiments indicated that the slow response was not due to abnormal persistence of PSP94 messenger RNA specifically in the DP and LP lobes in comparison with rPB. Thirdly, Western blot analysis revealed that both PSP94 and rPB expression is specific to the LP and DP at the protein level, exhibiting slow responses to testosterone replacement after castration. We conclude that PSP94 gene expression at the transcriptional level is more specific to the LP and DP than rPB and thus less sensitive to androgen ablation. This may have clinical implications for strategies to target the prostate in cancer therapy.

Androgen-Binding Protein↗
PubMed2001

Using gadolinium-infusion MR venography to show the impalpable testis in pediatric patients.

UNLABELLED: OBJECTIVE; This study evaluated the adjunctive value of gadolinium-infusion MR venography to locate the impalpable testis. SUBJECTS AND METHODS: Routine MR imaging and MR venography were performed in 34 patients presenting with impalpable testis. MR venography was performed by dynamic injection of gadopentetate dimeglumine bismethylamide with images taken at delayed venous phases. The site of the testis was determined by detection of the contrast-enhanced pampiniform venous plexus. RESULTS: A total of 44 impalpable testes were examined. Twenty-six hypoplastic canalicular testes, two testes at pelvic skinfold, four atrophic testes in the scrotum, and five intraabdominal testes were detected on both routine MR imaging and MR venography. Five "vanishing" testes in the scrotum and two at the groin region were detected by MR venography but not on MR imaging. CONCLUSION: Gadolinium-infusion MR venography is superior to MR imaging in the detection of atrophic testes. The method is a useful adjunct in patients with negative MR imaging findings.

Adolescent↗
PubMed2001

Detection of mRNA expression of gonadotropin-releasing hormone and its receptor in normal and neoplastic rat prostates.

Hypothalamic gonadotropin-releasing hormone (GnRH) plays a central role in the regulation of the mammalian reproductive systems as a releasing hormone of pituitary gonadotropins. However, a number of studies have shown that GnRH or its receptor are also expressed in some reproductive organs including prostate gland, mammary gland, ovary and placenta, tumors and tumor cell lines derived from these organs, suggesting that this peptide hormone may have other extrapituitary functions in addition to its role as a gonadotropin-releasing hormone. Moreover, it has been demonstrated that GnRH analogs exert some direct inhibitory effects on the proliferation of human and rat prostate cancer cells, probably mediated by its own specific receptors expressed in these tumor cells. In the present study, we investigated the mRNA expression of GnRH and its receptor in normal Noble rat prostate gland, and in three rat models of prostate cancer including the sex hormone-induced Noble rat model, an androgen-independent Noble rat prostatic tumor (AIT) and Dunning rat prostatic adenocarcinomas by RT-PCR and Southern blot analyses. The results showed that GnRH mRNA was expressed in the normal, hormone-treated and neoplastic rat prostates, in addition to its positive control expression in the hypothalamus, whereas its receptor was only detected in the androgen-dependent Dunning R3327H tumor. The detection of both GnRH and its receptor in the androgen-dependent Dunning R3327H tumor tissue suggests that this peptide hormone may have some autocrine and paracrine regulatory functions in this tumor. However, the gene expression of GnRH receptor was not detected in two androgen-independent Dunning tumor sublines and the Noble rat prostatic tumor, AIT, suggesting that the expression of GnRH receptor is lost or down-regulated in the prostatic tumors during the progression to a hormone-independent phenotype.

Adenocarcinoma↗
PubMed2000

Induction of apoptosis in prostate cancer cell lines by a flavonoid, baicalin.

The flavonoid baicalin (baicalein 7-D-beta-glucuronate), isolated from the dried root of Scutellaria baicalensis Georgi (Huang Qin), is widely used in the traditional Chinese herbal medicine for its anti-inflammatory, anti-pyretic and anti-hypersensitivity effects. In the present study, we investigated the in vitro effects of baicalin on the growth, viability, and induction of apoptosis in several human prostate cancer cell lines, including DU145, PC-3, LNCaP and CA-HPV-10. The cell viability after treating with baicalin for 2-4 days was quantified by a colorimetric 3-(4, 5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-s ulfophenyl)- 2H-tetrazolium (MTS) assay. The results showed that baicalin could inhibit the proliferation of prostate cancer cells. The responses to baicalin were different among different cell lines, with DU145 cells being the most sensitive and LNCaP cells the most resistant. Baicalin caused a 50% inhibition of DU145 cells at concentrations of 150 microM or above. The inhibition of proliferation of prostate cancer cells after a short period of exposure to baicalin was associated with induction by apoptosis, as evidenced by the typical nuclear fragmentation using Hoechst 33258 staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) labeling, DNA fragmentation, activation of caspase-3 and cleavage of poly-ADP-ribose polymerase (PARP). The results indicate that baicalin has direct anti-tumor effects on human prostate cancer cells.

Androgens↗
PubMed2000

Role of endothelium in thapsigargin-induced arterial responses in rat aorta.

We assessed the role of endothelium in the arterial response to thapsigargin, the Ca(2+)-ATPase inhibitor of the endoplasmic reticulum, in rat isolated aortic rings. Thapsigargin induced an endothelium-dependent relaxation of phenylephrine-contracted aortic rings with an EC(50) of 2.6+/-0.4 nM and a 75% maximum relaxation, while it was less effective against 30 mM K(+)-induced contraction. Pretreatment of aortic rings with N(G)-nitro-L-arginine methyl ester (30 microM) or methylene blue (1 microM) reduced thapsigargin-induced relaxation by approximately 85%. Thapsigargin failed to relax the endothelium-denuded rings. L-Arginine (3 mM) partially, but significantly, antagonized the effect of 30 microM N(G)-nitro-L-arginine methyl ester. Pretreatment with indomethacin (3 microM), glibenclamide (1 microM) or iberiotoxin (100 nM) did not alter the thapsigargin-induced relaxation. In contrast, pretreatment with tetrapentylammonium ions (TPA(+), 1-3 microM) or with 300 microM Ba(2+) suppressed the relaxant response to thapsigargin. TPA(+) (3 microM) also attenuated acetylcholine-induced relaxation. Thapsigargin-induced endothelium-dependent relaxation was primarily dependent on the presence of extracellular Ca(2+). Interestingly, when the tissues were exposed to very low concentrations of thapsigargin (1-3 nM) the nitric oxide-dependent relaxation induced by acetylcholine or A23187 was markedly reduced. While thapsigargin (3 nM) did not influence the relaxation induced by endothelium-independent dilators, sodium nitroprusside and verapamil. These results indicate that thapsigargin produced complex vascular effects primarily by acting on the endothelial cells. Thapsigargin causes an endothelial nitric oxide-dependent relaxation; on the other hand, it inhibits nitric oxide-mediated relaxation at the similar concentrations. Activation of TPA(+)- and Ba(2+)-sensitive but not Ca(2+)-activated or ATP-sensitive K(+) channels may be also involved in thapsigargin-induced relaxation of rat isolated aortic rings.

Animals↗
PubMed2000

PSP94 (or beta-microseminoprotein) is a secretory protein specifically expressed and synthesized in the lateral lobe of the rat prostate .

BACKGROUND: Prostatic secretory protein of 94 amino acids (PSP94), also called beta-microseminoprotein, is a small, nonglycosylated protein, rich in cysteine residues. It was first isolated as a major protein from human seminal plasma. Subsequently, its homologous proteins were identified, and their cDNAs or genes have been cloned in primates, pigs, and rodents. METHODS: The present study investigated the expression pattern of PSP94 in the normal Noble rat prostate gland by nonradioactive in situ hybridization, Northern blotting, RT-PCR, Western blotting, and immunohistochemistry. Its expression in the mouse prostate gland was also examined by in situ hybridization. RESULTS: The results of in situ hybridization, and Northern and Western blot analyses, showed that the expression of rat PSP94 was prostate-specific. It was highly expressed in the lateral prostatic lobe, moderate in the dorsal lobe, weak in the coagulating gland, and negative in the ventral lobe and seminal vesicle. Its specific expression in the rat prostate gland was further confirmed by RT-PCR analysis of prostatic and nonprostatic organ tissues. Its mRNA transcripts were not detected in the urinary, digestive, and respiratory tracts, male and female reproductive organs, muscles, brain, and kidney. Its molecular mass was estimated to be 14.5 kDa by Western blotting. Similar prostate-specific expression of PSP94 was also observed by in situ hybridization in the lateral lobe, but not in the dorsal and ventral lobe, of the mouse prostate gland. CONCLUSIONS: Rat PSP94 is a major secretory protein highly expressed and synthesized by the lateral lobe of both rat and mouse prostate glands, and moderately expressed in the dorsal lobe of the rat prostate gland.

Animals↗
PubMed2000

Abolition of endothelium-dependent relaxation in the rat aorta by tetraoctylammonium ions.

Quaternary ammonium ions are common pharmacological probes used to study the kinetic properties of K+ channels in smooth muscle cells. On the other hand, some ammonium compounds cause vasorelaxation through unknown mechanisms. The main aim of this study was to examine a unique role of endothelium in the vascular response to tetraoctylammonium ions (TOA+) in the isolated rat aorta. Changes in contractile force were measured by force transducers and total tissue content of cGMP was measured by radioimmunoassay. Endothelial cytosolic Ca2+ ([Ca2+]i) was assessed by laser scanning confocal microscopy.

Acetylcholine↗
PubMed2000

Serial HRCT lung changes after 3-field radiation treatment of breast cancer.

AIMS: To document serial high resolution computed tomography (HRCT) features of lung injury after 3-field radiotherapy for breast cancer. MATERIALS AND METHODS: Thirty women who received opposing tangential chest wall and supraclavicular field (SCF) irradiation after breast surgery were recruited. Thoracic HRCT was performed before and at 1, 3, 6 and 12 months after radiotherapy (RT). Lung injury at 3 months was quantified by applying a scoring system to each HRCT section. Findings were correlated with spirometric lung function tests. RESULTS: There was HRCT evidence of lung injury in 27 (90%) women at 1 month and in all 30 patients at 3 months. Spirometric lung function declined post-RT (P < 0.05), correlating with an increased SCF acute lung injury score at 3 months [r = -0.54 and -0.46, P = 0.01 and 0.03 for forced expiratory volume in 1st (FEV(1)) and forced vital capacity (FVC), respectively]. Lung injury on HRCT progressed from ground glass opacification at 1 month to nodular consolidation (3 months), increasing linear densities (6 months), and finally to residual subpleural linear and dense opacities (12 months). CONCLUSION: There is a high incidence of lung injury associated with 3-field radiotherapy for breast cancer, with concurrent SCF irradiation increasing the risk of lung damage and functional impairment. A characteristic sequence of HRCT changes is seen in most patients receiving this type of radiotherapy.Ooi, G. C. (2000). Clinical Radiology55, 817-824.

Adult↗
PubMed2000

Value of intra-arterial calcium stimulated venous sampling for regionalization of pancreatic insulinomas.

BACKGROUND: Intra-arterial calcium stimulation with hepatic venous sampling (ASVS) for insulin gradients has been reported to be the most sensitive preoperative localizing technique for insulinomas. We reviewed our experience with ASVS to localize and guide the treatment of insulinomas over the past decade. METHODS: Eighteen patients who underwent ASVS before surgical exploration for insulinoma were studied. The accuracy of ASVS was compared with intraoperative findings and other localizing studies. RESULTS: There were no complications arising from the procedures. A more than 2-fold step-up in insulin level 30 to 60 seconds after injection to at least 1 feeding artery was observed in 16 patients. Fourteen of the 16 solitary tumors (87.5%) were correctly located; 100% (6/6 tumors) at the head and 80% (8/10 tumors) at the body/tail. The overall accuracy of this test was 89%, compared with 11%, 33%, 38%, and 63% of ultrasonography, computed tomography, magnetic resonance imaging, and endoscopic ultrasonography, respectively. Six enucleations and 10 distal resections were performed, which included 2 laparoscopic procedures. The combination of intraoperative ultrasonography with preoperative ASVS identified all tumors. CONCLUSIONS: ASVS is the most accurate preoperative localization tool for the localization of insulinomas and, in combination with intraoperative ultrasonography, can enhance surgical success.

Adult↗
PubMed2000

A protein kinase G-sensitive channel mediates flow-induced Ca(2+) entry into vascular endothelial cells.

The hemodynamic force generated by blood flow is considered to be the physiologically most important stimulus for the release of nitric oxide (NO) and prostacyclin (PGI(2)) from vascular endothelial cells (1). NO and PGI(2) then act on the underlying smooth muscle cells, causing vasodilation and thus lowering blood pressure (2, 3). One critical early event occurring in this flow-induced regulation of vascular tone is that blood flow induces Ca(2+) entry into vascular endothelial cells, which in turn leads to the formation of NO (4, 5). Here we report a mechanosensitive Ca(2+)-permeable channel in vascular endothelial cells. The activity of the channel was inhibited by 8-Br-cGMP, a membrane-permeant activator of protein kinase G (PKG), in cell-attached membrane patches. The inhibition could be reversed by PKG inhibitor KT5823 or H-8. A direct application of active PKG in inside-out patches blocked the channel activity. Gd(3+), Ni(2+), or SK&F-96365 also inhibited the channel activity. A study of fluorescent Ca(2+) entry revealed a striking pharmacological similarity between the Ca(2+) entry elicited by flow and the mechanosensitive Ca(2+)-permeable channel we identified, suggesting that this channel is the primary pathway mediating flow-induced Ca(2+) entry into vascular endothelial cells.

Alkaloids↗
PubMed2000

Surfactant tracheobronchial lavage for the management of a rabbit model of meconium aspiration syndrome.

We evaluated the effect of tracheobronchial lavage with diluted surfactant solution (bovine lipid extract surfactant, bLES) in a rabbit model of meconium aspiration. All animals were anaesthetized, tracheotomized and given 3-4 ml/kg of 25% slurry of human meconium into the endotracheal tube and mechanically ventilated for 1 h. The animals were then randomly assigned to surfactant lavage (n = 12) with 15 ml/kg of diluted surfactant at a concentration of 5.4 mg phospholipid/ml administered in aliquots of 2 ml; or simple endotracheal suction (control n = 12) when the oxygenation index (OI) was >/=15. Changes in the arterial blood gases and the histomorphological and radiological appearances of the lungs were recorded. The OI and arterial/alveolar oxygen tension (a/A PO2) of the surfactant lavage group improved significantly at 5 min post-treatment, and these improvements were observed throughout the ensuing 4 h of ventilation. There was significantly more solid content recovered by surfactant lavage compared with the control group (p = 0.0001). Radiologically, the post-treatment air space opacification scores of the lavage group were significantly lower compared with the control (p = 0.002). The post-treatment radiographs of the lavage-treated rabbits were rated by the radiologist, who was blinded to the treatment groups, as much improved in 5 and improved in 4, whereas the control rabbits were rated as much worse in 3 and worse in 4. Histological examination showed the lungs of the lavaged rabbits had significantly more normal airway (p < 0.0001), more fields showing completely normal airspace (p = 0.0001) and less fields showing severe overdistension with meconium (p = 0.0005). We concluded that lavage with diluted surfactant solution effectively washed out the meconium, improved gases exchanges, and improved the histological and radiological appearances in the rabbit model of MAS.

Animals↗
PubMed2000

A comparative study of hormonal regulation of three secretory proteins (prostatic secretory protein-PSP94, probasin, and seminal vesicle secretion II) in rat lateral prostate.

The rat dorsolateral prostate secretes several major known proteins, although their physiological and reproductive functions are largely undefined. In the present study we examined and compared the in vivo hormonal regulation of the messenger RNA (mRNA) expression of three major secretory proteins, including prostatic secretory protein of 94 amino acids (PSP94 or beta-microseminoprotein), probasin, and seminal vesicle secretion II (SVSII), in long-term castrated lateral prostates (LP) by in situ hybridization and semiquantitative RT-PCR. The protein levels of PSP94 in the castrated LPs were also examined by Western blotting. PSP94 is a small protein newly isolated from the rat prostate gland and demonstrates highly specific expression in the LP. The results of in situ hybridization showed that PSP94, probasin, and SVSII were highly expressed in the intact LP. The hybridization signals of probasin and PSP94 disappeared in the 60-day postcastrated LPs, whereas the signals of SVSII dropped sharply in the 14-day postcastrated LPs. Similar patterns of decreasing mRNA levels of the three proteins in the castrated LPs were observed by RT-PCR analysis. Their mRNA transcripts were restored to normal levels after replacement with testosterone. The results indicate that these secretory proteins are all under androgen regulation in the rat LP. Interestingly, we also observed that their degrees of sensitivity or responsiveness to androgen withdrawal are different. Their mRNA levels dropped in response to duration of castration in the following decreasing order: SVSII, PSP94, and probasin. Besides androgen [dihydrotestosterone (DHT)], we also examined the effects of glucocorticoid [dexamethasone (DEX)], progestin [medroxyprogesterone acetate (MPA)], and zinc on their gene expressions in castrated LPs. We observed that the mRNA transcripts of both PSP94 and probasin were increased after treatments with DHT, DEX, and MPA, suggesting that these two proteins could also be regulated by glucocorticoid and progestin. In contrast with probasin, PSP94 and SVSII were not induced by ZnSO4 treatment. On the other hand, SVSII expression was only increased significantly by DHT and moderately by MPA, but not by DEX, suggesting that SVSII is under strict control by androgen.

Androgen-Binding Protein↗
PubMed2000

Esophageal atresia and tracheal stenosis: use of three-dimensional CT and virtual bronchoscopy in neonates, infants, and children.

OBJECTIVE: The objective of this study was to evaluate the use of three-dimensional CT and virtual bronchoscopy in the treatment of neonates, infants, and children with esophageal atresia and tracheal stenosis. CONCLUSION: Long-gap (n = 1) and short-gap (n = 5) esophageal atresia, long-segment stenosis (n = 2), patent poststenting trachea (n = 1), normal trachea without fistula (n = 1), and tracheal bronchus (n = 1) were studied. Fistulas between the lower esophagus and carina were noted in all six cases of esophageal atresia. All CT findings correlated with operative or bronchoscopy findings. Sensitivity and specificity were 100%. Three-dimensional CT and virtual bronchoscopy are accurate and useful techniques in the preoperative assessment of esophageal atresia and tracheal stenosis in neonates, infants, and children.

Bronchoscopy↗
PubMed1999

A case-controlled MRI/MRA study of neurovascular contact in hemifacial spasm.

BACKGROUND: Neurovascular contact (NVC) with the root exit zone (REZ) of the ipsilateral facial nerve is associated with hemifacial spasm (HFS), but unresolved issues remain. OBJECTIVES: To 1) determine the frequency of symptomatic and nonsymptomatic NVC, 2) determine the features of NVC associated with HFS, and 3) correlate severity of HFS to these features. METHODS: Two independent, blinded, prospective assessments of high-resolution MR and MR angiography (MRA) images were performed on Chinese cases (HFS: n = 44; age-matched control subjects: n = 20). RESULTS: Over 88% of 44 symptomatic sides in patients with HFS had NVC of the ipsilateral facial nerve. At least 80% of symptomatic sides involved NVC at the anterior aspect of the REZ [REZ(ant.)]. Although NVC was observed in approximately half of nonsymptomatic sides, at least 70% of them were not at REZ(ant.). NVC at the cisternal and intracanalicular portions of the facial nerve were not associated with HFS. Half of our patients with HFS had bilateral NVC, but none had bilateral symptoms. Most of our MR/MRA images showed that the size and position of the arterial branches of the vertebrobasilar system were markedly asymmetric. Of patients with bilateral NVC, over 83% had asymmetric NVC sites. The anterior inferior cerebellar artery was the most common vessel involved in NVC, but was not significantly associated with HFS. Most of the NVC involved one vessel at one contact point with no indentation. The development of HFS was significantly associated with nerve indentation in NVC. The development and severity of HFS were not associated with multiple contact points in NVC. No significant interobserver variability existed between the blinded assessments. CONCLUSIONS: MRI/MR angiography are accurate, fast, and safe in characterizing neurovascular contact (NVC) at the brainstem. The site of NVC and ipsilateral facial nerve indentation in NVC are significant determinants for the development of hemifacial spasm (HFS). The lack of bilateral NVC at the anterior aspect of the root exit zone of the facial nerve could explain in part the lack of bilateral symptoms. The development and severity of HFS are not associated with a specific blood vessel or multiple contact points in NVC.

Adult↗
PubMed1999

In situ hybridization study of PSP94 (prostatic secretory protein of 94 amino acids) expression in human prostates.

BACKGROUND: The prostatic secretory protein of 94 amino acids (PSP94), also named beta-microseminoprotein, is one of the major proteins secreted by the human prostate. However, its value as a prognostic marker for prostate cancers is still under debate. The aim of the present study was to examine the expression pattern of this protein in fetal, pubertal, and aged human prostates. METHODS: Nonisotopic in situ hybridization using a digoxigenin-labeled riboprobe for PSP94 and immunohistochemistry were used to demonstrate the expression of PSP94 in different regions or zones of fetal, pubertal, and adult human prostates. Its localization pattern was also compared with those of two other major secretory proteins, prostate-specific antigen (PSA) and prostatic acid phosphatase (PAP), by immunohistochemistry. RESULTS: PSP94 mRNA and its protein were localized to the secretory epithelium of normal pubertal and adult human prostates. No hybridization signal and immunoreactivity of PSP94 were seen in fetal prostates at 6-7 months of gestation, whereas some glandular cells were positive to PSA and PAP immunostainings. In the adult prostates, PSP94 expression was intense in the acini in the peripheral zone, less intense in the transition zone, and variable in the central zone. Such a zonal expression pattern was more apparent in the pubertal prostates. However, no obvious differential expression pattern was observed in the immunohistochemistry of PAP and PSA, which showed a uniform staining of the secretory epithelia of the acini in all anatomic zones. The hybridization signals and immunoreactivity of PSP94 became reduced or lost in premalignant prostatic intraepithelial neoplastic lesions and different grades of prostatic carcinomas. CONCLUSIONS: Fetal prostates at 6-7 months of gestation already synthesize PSA and PAP but not PSP94. The delayed expression of PSP94 appears to correlate with the development of the prostate gland. A differential expression pattern of PSP94 is demonstrated in different anatomical zones, showing that this protein is more expressed and synthesized in the acini in the peripheral zone than in the central and transition zones. However, such a zonal pattern is not seen in the immunohistochemistry of PSA and PAP. The present study also shows that PSP94 is downregulated in different grades of prostate cancers.

Adolescent↗
PubMed1999

Differential expression of PSP94 in rat prostate lobes as demonstrated by an antibody against recombinant GST-PSP94.

Prostate secretory protein (PSP94, 94 amino acids) is one of the most abundant proteins secreted from the prostate. Its biological role is unknown and still controversial, although it is assumed to have the potential to be a biomarker and a suppressor of prostate cancer. In order to establish an animal model to further elucidate its biological role, we expressed the mature form of rat PSP94 in Escherichia coli, using a glutathione S-transferase (GST) fusion expression vector; we generated a polyclonal rabbit antibody against the recombinant protein. The antibody specifically recognized recombinant rat PSP94 and cross-reacted only very weakly with its human homologue. Using the characterized anti-rat PSP94 antibody, we found that PSP94 was located primarily in rat prostate. Furthermore, PSP94 is present at different levels in different lobes of rat prostate, with significant levels detectable only in the lateral lobe (LP). In addition, the most abundant PSP94 expression was found in the prostate lobe secretions, and PSP94 levels in LP secretions were at least seven times higher than in secretions from the dorsal prostate (DP). The rat ventral prostate (VP) and other regions of the male accessory glands were found to be almost completely devoid of PSP94. Since most rat prostate dysplasia induced by steroid hormone treatment occurs only in dorsolateral prostate, prostate tissue-specific expression and the expression of PSP94 in dorsolateral, but not other, lobes of the prostate suggest a potential role in prostate targeting and prostate cancer development.

Animals↗
PubMed1999

Involvement of endothelium/nitric oxide in vasorelaxation induced by purified green tea (-)epicatechin.

The present study investigated the involvement of endothelial nitric oxide in relaxation induced by purified green tea (-)epicatechin in rat isolated mesenteric arteries. (-)Epicatechin caused both endothelium-dependent and -independent relaxation. NG-Nitro-L-arginine methyl ester (L-NAME, 100 microM) and methylene blue (10 microM) significantly attenuated (-)epicatechin-induced relaxation in endothelium-intact tissues. L-Arginine (1 mM) partially antagonized the effect of L-NAME. (-)Epicatechin-induced relaxation was inhibited by Rp-guanosine 3',5'-cyclic monophosphothioate triethylamine. In contrast, indomethacin and glibenclamide had no effect. (-)Epicatechin (100 microM) significantly increased the tissue content of cyclic GMP and NG-nitro-L-arginine (100 microM) or removal of the endothelium abolished this increase. (-)Epicatechin (100 microM) induced an increase in intracellular Ca2+ levels in cultured human umbilical vein endothelial cells. Iberiotoxin at 100 nM attenuated (-)epicatechin-induced relaxation in endothelium-intact arteries and this effect was absent in the presence of 100 microM L-NAME. In summary, (-)epicatechin-induced endothelium-dependent relaxation is primarily mediated by nitric oxide and partially through nitric oxide-dependent activation of iberiotoxin-sensitive K+ channels. In addition, there may be a causal link between increased Ca2+ levels and nitric oxide release in response to (-)epicatechin.

Animals↗