Long-distance RNA-RNA interactions and conserved sequence elements affect potato virus X plus-strand RNA accumulation

Conserved octanucleotide sequences located upstream of two major potato virus X (PVX) subgenomic RNAs (sgRNAs), as well as elements in the 5' end of the genome, affect accumulation of sgRNA. To determine if complementarity between these sequences is important for PVX RNA accumulation, we analyzed the effects of mutations within these elements and compensatory mutations in a tobacco protoplast system and in plants. Mutations in the 5' nontranslated region (NTR mutants) that reduced complementarity resulted in lower genomic RNA (gRNA) and sgRNA levels, whereas mutations to the octanucleotide elements affected only the corresponding sgRNA levels. However, for both the NTR and octanucleotide mutants, the extent of reductions in RNA levels did not directly correlate with the degree of complementarity, suggesting that the sequences of these elements are also important. Mutants containing changes in the NTR and compensatory changes in one of the octanucleotide elements restored levels of gRNA and the other sgRNA species with an unaltered octanucleotide element to those of wild-type. Although compensatory changes significantly increased levels of the sgRNA species with the modified octanucleotide element, levels were not restored to those of wild-type. Our data indicate that long distance RNA-RNA interactions and the sequences of the interacting elements are required for PVX plus-strand RNA accumulation.

Action of retinoids on embryonic and early postnatal testis development

The current study investigates the hypothesis that retinoids have a role in embryonic testis development. The action of retinoids on testis development and the expression of retinoic acid receptors (RAR alpha, RAR beta, RAR gamma) were examined. In embryonic day 13 (E13; plug date = E0) testis organ cultures an RAR-selective agonist and all-trans retinoic acid completely inhibited seminiferous cord formation. In contrast, an RAR alpha-selective antagonist had no effect. RT-PCR demonstrated that RAR alpha messenger RNA (mRNA) was expressed at all developmental time points evaluated, which included embryonic day 14 (E14) through postnatal day 30 (P30). Expression of RAR beta mRNA was present at E15 through P2, whereas RAR gamma mRNA was expressed at E18 through P2. Cellular localization of receptors by immunohistochemistry indicated that RAR alpha was localized to the interstitium at E18 and to the seminiferous cords by P0. RAR beta and RAR gamma were detected in both interstitium and cords at E16 and by E18 were mainly expressed in the cords. At P0 RAR beta and RAR gamma were localized to the germ cell populations. To examine retinoid actions, the growth of P0 testis cultures were investigated. Interestingly, retinol and retinoic acid did not inhibit growth of P0 testis cultures but did inhibit the action of growth stimulators. Retinoic acid inhibited FSH, EGF, and 10% calf serum stimulated growth in P0 testis cultures. The hypothesis tested was that the inhibitory effects of retinoids on P0 testis growth may be mediated through the growth inhibitor, transforming growth factor-beta (TGF beta). The action of retinoids on TGF beta mRNA expression was examined in P0 testis cultures. Retinoic acid stimulated TGFbeta3 mRNA expression within 24 h and increased expression of TGFbeta1 and TGFbeta2 after 72 h. Retinol increased expression of TGFbeta1 and TGFbeta2 but not TGFbeta3 after 72 h of treatment. These observations indicate that retinoic acid can influence seminiferous cord formation and testis growth. The inhibitory actions of retinoids may in part be mediated through increased expression of TGFbeta isoforms.

Gonadotropin-releasing hormone immunoreactivity in the adult and fetal human olfactory system

Studies in fetal brain tissue of rodents, nonhuman primates and birds have demonstrated that cells containing gonadotropin-releasing hormone (GnRH) migrate from the olfactory placode across the nasal septum into the forebrain. The purpose of this study was to examine GnRH neurons in components of the adult and fetal human olfactory system. In the adult human brain (n=4), immunoreactive GnRH was evident within diffusely scattered cell bodies and processes in the olfactory bulb, olfactory nerve, olfactory cortex, and nervus terminalis located on the anterior surface of the gyrus rectus. GnRH-immunoreactive structures showed a similar distribution in 20-week human fetal brains (n=2), indicating that the migration of GnRH neurons is complete at this time. In 10-11-week fetal brains (n=2), more cells were noted in the nasal cavity than in the brain. Our data are consistent with observations made in other species, confirming olfactory derivation and migration of GnRH neurons into the brain from the olfactory placode.

P-glycoprotein (Pgp) does not affect the cytotoxicity of flavonoids from Sophora flavescens, which also have no effects on Pgp action

Sophoraflavanone, kurarinone (GS08), norkurarinol (GS11), kurarinol (GS12) and kushenol K are cytotoxic flavonoids isolated from Sophora flavescens. In this study, we tested the cytotoxicity of those flavonoids to human cancer cells including P-glycoprotein (Pgp)-expressing HCT15 cells and its multidrug resistant subline, HCT15/CL02 cells. HCT15/CL02 cells revealed resistance to GS08, GS11 and GS12 about 2 fold in comparison with HCT15 cells. Nonetheless, verapamil, a Pgp inhibitor, could not increase the cytotoxicity of all the flavonoids tested. We also investigated that the flavonoids could modulate the Pgp action. At nontoxic concentrations, the flavonoids could not effect on the cytotoxicity of paclitaxel, a well-known Pgp-substrate. The flavonoids also had no effects on the accumulation of rhodamine 123 in all the cells tested at 10 microM. From the results, we concluded that Pgp had no effect on the cytotoxicity of the flavonoids, and the flavonoids also had no effect on the action of Pgp. Our results also suggested that HCT15/CL02 cells had additional mechanisms for drug resistance distinct from Pgp overexpression.

Phosphorylation and regulation of choline kinase from Saccharomyces cerevisiae by protein kinase A

The CKI1-encoded choline kinase (ATP:choline phosphotransferase, EC 2.7.1.32) from Saccharomyces cerevisiae was phosphorylated in vivo on multiple serine residues. Activation of protein kinase A activity in vivo resulted in a transient increase in the phosphorylation of choline kinase. This phosphorylation was accompanied by a stimulation in choline kinase activity. In vitro, protein kinase A phosphorylated choline kinase on a serine residue with a stoichiometry (0.44 mol of phosphate/mol of choline kinase) consistent with one phosphorylation site/choline kinase subunit. The major phosphopeptide derived from the enzyme phosphorylated in vitro by protein kinase A was common to one of the major phosphopeptides derived from the enzyme phosphorylated in vivo. Protein kinase A activity was dose- and time-dependent and dependent on the concentrations of ATP (Km 2.1 microM) and choline kinase (Km 0.12 microM). Phosphorylation of choline kinase with protein kinase A resulted in a stimulation (1.9-fold) in choline kinase activity whereas alkaline phosphatase treatment of choline kinase resulted in a 60% decrease in choline kinase activity. The mechanism of the protein kinase A-mediated stimulation in choline kinase activity involved an increase in the apparent Vmax values with respect to ATP (2.6-fold) and choline (2.7-fold). Overall, the results reported here were consistent with the conclusion that choline kinase was regulated by protein kinase A phosphorylation.

Bilateral ovarian carcinoma metastatic from the ampulla of Vater: a rare Krukenberg tumor

Carcinoma of the ampulla of Vater is a relatively rare neoplasm and its longterm survival rate is considerably high. However, because of differences in tumor pathologic features and local invasiveness, a 5-year survival rate differ widely. We present a case of metastatic carcinoma of the ampulla of Vater presenting as a Krukenberg tumor in a 59-year-old woman. Eight months earlier, she had been diagnosed as well-differentiated adenocarcinoma of the ampulla of Vater. Abdominal examination revealed a hard mass with mild tenderness in the RLQ area. The laboratory findings were unremarkable except for mild anemia. CT scan of the abdomen revealed enlargement of both ovaries. An exploratory laparotomy disclosed bilateral ovarian masses, 18 x 12 x 8 cm and 8 x 5.5 x 4 cm in size, respectively. Histologic findings of the both ovarian masses were consistent with metastatic adenocarcinoma from the ampulla of Vater.

Antibodies to human T-cell lymphotropic virus type I (HTLV-I) by particle agglutination (PA) test in Korean blood donors

HTLV-I infection is a recently recognized disease entity that is common in some tropical and subtropical areas, including the southwestern district of Japan. Despite the geographical proximity and frequent cultural exchanges between Korea and Japan, it is understood that Korea is not an endemic area and HTLV-I-associated illnesses are very rare in Korea. This study was designed to evaluate the positive rate of anti-HTLV-I antibodies in Korean blood donors and its regional distribution. Sera were obtained from blood donors from various districts around Korea. Anti-HTLV-I antibodies were detected by using the microtiter particle agglutination test employing an indirect agglutination technique. A total of 9,281 donors were tested and 12 donors (0.13%) were positive for anti-HTLV-I antibodies, 10 (0.11%) out of 8,845 males and 2 (0.46%) out of 436 females, with relative female predominance. A relatively high incidence of anti-HTLV-I positive donors was observed in Cheju Island (0.80%), Kyungnam (0.31%), and Chonnam (0.15%). In conclusion, the positive rate of anti-HTLV-I antibodies seemed to be very low in Korea, but the highest positive rate of anti-HTLV-I antibodies was noticed on Cheju Island, warranting further research for confirmation.

Melatonin and taurine reduce early glomerulopathy in diabetic rats

Oxidative stress occurs in diabetic patients and experimental models of diabetes. We examined whether two antioxidants, melatonin and taurine, can ameliorate diabetic nephropathy. Enhanced expression of glomerular TGF-beta1 and fibronectin mRNAs and proteinuria were employed as indices of diabetic nephropathy. Experimental diabetes was induced by intravenous injection of streptozotocin 50 mg/kg. Two days after streptozotocin, diabetic rats were assigned to one of the following groups: i) untreated; ii) melatonin supplement by 0.02% in drinking water; or iii) taurine supplement by 1% in drinking water. Four weeks after streptozotocin, diabetic rats (n = 6: plasma glucose 516+/-12 mg/dl) exhibited 6.1 fold increase in urinary protein excretion, 1.4 fold increase in glomerular TGF-beta1 mRNA, 1.7 fold increase in glomerular fibronectin mRNA, 2.2 fold increase in plasma lipid peroxides (LPO), and 44 fold increase in urinary LPO excretion above the values in control rats (n = 6: plasma glucose 188+/-14 mg/dl). Chronic administration of melatonin (n = 6) and taurine (n = 6) prevented increases in glomerular TGF-beta1 and fibronectin mRNAs and proteinuria without having effect on blood glucose. Both treatments reduced lipid peroxidation by nearly 50%. The present data demonstrate beneficial effects of melatonin and taurine on early changes in diabetic kidney and suggest that diabetic nephropathy associated with hyperglycemia is largely mediated by oxidative stress.

Cytotoxicity of two novel cisplatin analogues, (CPA)2Pt[DOLYM] and (DACH)Pt[DOLYM], to human cancer cells in vitro

Despite the impressive antitumor activity of cisplatin, two major limitations of the drug, that is severe side effects and drug-resistance of cancer cells, make its use difficult for cancer therapy. These limitations have resulted in a great deal of effort having been expended into structural modifications of cisplatin. In this study, we tested two novel cisplatin analogues, (CPA)2Pt [DOLYM] (COMP-I) and (DACH)Pt[DOLYM] (COMP-II), for the mode of cytotoxic action against human tumor cells comparing with cisplatin and carboplatin in vitro. These two novel analogues had considerable cytotoxic activities against five kinds of human solid tumor cells, and especially COMP-II was more effective on HCT15 colon cancer cells than other compounds. In addition, COMP-II had cytostatic activity at low concentrations (10-0.3 microgram/ml), but other compounds revealed little effect on tumor growth at the low concentration.

Elevated serum levels of transforming growth factor-beta1 in patients with colorectal carcinoma: its association with tumor progression and its significant decrease after curative surgical resection

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) acts as a potent inhibitor of cell growth and tumor progression but loss of this negative regulation can contribute to tumor development. Some studies have reported an association between disease progression and TGF-beta1 expression in patients with colorectal carcinoma, but their results were not always consistent.

METHODS

Serum levels of TGF-beta1 were measured using an enzyme-linked immunoadsorbent assay in 121 consecutive patients with colorectal carcinoma and compared with TGF-beta1 serum levels in 31 healthy volunteers. Serum levels of TGF-beta1 also were measured in 50 patients who underwent curative surgical resection (part of the 121 preoperative patients) to compare their levels with preoperative serum levels of TGF-beta1.

RESULTS

Serum levels of TGF-beta1 in patients with colorectal carcinoma (45+/-15 ng/mL) (mean+/-the standard deviation) were significantly higher than those in the healthy control group (32+/-4 ng/mL) (P = 0.001). Serum levels of TGF-beta1 increased with increasing tumor stage (P < 0.01). Serum levels of TGF-beta1 were correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, and serum levels of carcinoembryonic antigen (CEA). Serum levels of TGF-beta1 tended to increase with increasing CEA (correlation coefficient = 0.21; P < 0.05). The mean serum level of TGF-beta1 in patients with colorectal carcinoma before surgery (45+/-14 ng/mL) (n = 50) significantly decreased to 34+/-7 ng/mL, which was within the normal range (32+/-4 ng/mL), after curative surgical resection of the tumor (P = 0.0000). Serum levels of TGF-beta1 after tumor resection decreased more significantly in patients with higher preoperative levels of TGF-beta1 (from 53+/-12 ng/mL to 36+/-6 ng/mL) (n = 30).

CONCLUSIONS

The results of the current study suggest that serum levels of TGF-beta1 in colorectal carcinoma patients may be associated with disease progression and may be used as a biomarker in the management of colorectal carcinoma patients. The authors believe further studies with a large number of patients for a longer follow-up period are necessary to conclude whether serum levels of TGF-beta1 carry significant clinical relevance.

Elevated serum levels of transforming growth factor-beta1 in patients with colorectal carcinoma: its association with tumor progression and its significant decrease after curative surgical resection

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) acts as a potent inhibitor of cell growth and tumor progression but loss of this negative regulation can contribute to tumor development. Some studies have reported an association between disease progression and TGF-beta1 expression in patients with colorectal carcinoma, but their results were not always consistent.

METHODS

Serum levels of TGF-beta1 were measured using an enzyme-linked immunoadsorbent assay in 121 consecutive patients with colorectal carcinoma and compared with TGF-beta1 serum levels in 31 healthy volunteers. Serum levels of TGF-beta1 also were measured in 50 patients who underwent curative surgical resection (part of the 121 preoperative patients) to compare their levels with preoperative serum levels of TGF-beta1.

RESULTS

Serum levels of TGF-beta1 in patients with colorectal carcinoma (45+/-15 ng/mL) (mean+/-the standard deviation) were significantly higher than those in the healthy control group (32+/-4 ng/mL) (P = 0.001). Serum levels of TGF-beta1 increased with increasing tumor stage (P < 0.01). Serum levels of TGF-beta1 were correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, and serum levels of carcinoembryonic antigen (CEA). Serum levels of TGF-beta1 tended to increase with increasing CEA (correlation coefficient = 0.21; P < 0.05). The mean serum level of TGF-beta1 in patients with colorectal carcinoma before surgery (45+/-14 ng/mL) (n = 50) significantly decreased to 34+/-7 ng/mL, which was within the normal range (32+/-4 ng/mL), after curative surgical resection of the tumor (P = 0.0000). Serum levels of TGF-beta1 after tumor resection decreased more significantly in patients with higher preoperative levels of TGF-beta1 (from 53+/-12 ng/mL to 36+/-6 ng/mL) (n = 30).

CONCLUSIONS

The results of the current study suggest that serum levels of TGF-beta1 in colorectal carcinoma patients may be associated with disease progression and may be used as a biomarker in the management of colorectal carcinoma patients. The authors believe further studies with a large number of patients for a longer follow-up period are necessary to conclude whether serum levels of TGF-beta1 carry significant clinical relevance.

Synthesis and evaluation of 2-amino-6-fluoro-9-(4-hydroxy-3-hydroxymethylbut-1-yl)purine mono- and diesters as potential prodrugs of penciclovir

2-Amino-6-fluoro-9-(4-hydroxy-3-hydroxymethylbut-1-yl)purine (7), and its mono- and diesters 8-15 were prepared and evaluated for their potential as prodrugs of penciclovir. Treatment of 2-amino-6-chloro-9-(4-hydroxy-3-hydroxymethylbut-1-yl)purine (5) with trimethylamine in THF followed by a reaction of the resulting trimethylammonium chloride salt 6 with KF in DMF afforded 2-amino-6-fluoro-9-(4-hydroxy-3-hydroxymethylbut-1-yl)purine (7) in 80% yield. Esterification of 7 with an appropriate acid anhydride [Ac2O, (EtCO)2O, (n-PrCO)2O, or (i-PrCO)2O] in DMF in the presence of a catalytic amount of DMAP produced the mono-esters 8-11 in 42-45% yields and diesters 12-15 in 87-99% yields. Of the prodrugs tested in rats, the monoisobutyrate 11 was the most efficiently absorbed and metabolized to 7, showing the mean maximum total concentration of penciclovir (5.5 microg/mL) and 7 (10.8 microg/mL) in the blood was much higher than the mean maximum concentration of penciclovir (11.5 microg/mL) from famciclovir. However, the mean concentrations of penciclovir from 11 were lower than those from famciclovir because of the limited conversion of a major metabolite 7 to penciclovir by adenosine deaminase.

Apoptosis in Helicobacter pylori-associated gastric and duodenal ulcer disease is mediated via the Fas antigen pathway

Increased mucosal apoptosis is seen in H. pylori-infected gastric tissue; however, the precise mechanism by which this organism triggers programmed cell death is poorly understood and is investigated in this study. One pathway for induction of apoptosis is the Fas Ag pathway. Normal gastric and small bowel tissue express low levels of Fas antigen and nondetectable levels of Fas ligand. Consequent to H. pylori infection, there is elevated expression of Fas antigen in mucosal cells concurrent with Fas ligand expressing lymphocytes. This prompted us to investigate the potential role of Fas in mediating H. pylori-related apoptosis. It has been shown that inflammatory cytokines are abundant in H. pylori-infected tissue and that cytokines regulate the expression of Fas Ag in various tissue types. Using cell culture, we examine the role of specific inflammatory cytokines in activating this pathway. This communication presents the first evidence to implicate the Fas pathway in mediating apoptosis in H. pylori-associated gastric and duodenal ulcer disease.

Strain-dependent induction of allergic sensitization caused by peanut allergen DNA immunization in mice

To investigate the potential application of allergen gene immunization in the modulation of food allergy, C3H/HeSn (C3H) mice received i.m. injections of pAra h2 plasmid DNA encoding one of the major peanut allergens, Ara h2. Three weeks following pDNA immunization, serum Ara h2-specific IgG2a, IgG1, but not IgE, were increased significantly in a dose-dependent manner. IgG1 was 30-fold higher in multiply compared with singly immunized mice. Ara h2 or peanut protein injection of immunized mice induced anaphylactic reactions, which were more severe in multiply immunized mice. Heat-inactivated immune serum induced passive cutaneous anaphylaxis, suggesting that anaphylaxis in C3H mice was mediated by IgG1. IgG1 responses were also induced by intradermal injection of pAra h2, and by i.m. injection of pOMC, the plasmid DNA encoding the major egg allergen protein, ovomucoid. To elucidate whether the pDNA immunization-induced anaphylaxis was a strain-dependent phenomenon, AKR/J and BALB/c mice also received multiple i.m. pAra h2 immunizations. Injection of peanut protein into these strains at weeks 3 or 5 following immunization did not induce reactions. Although IgG2a was increased significantly from week 2 in AKR/J mice and from week 4 in BALB/c mice and remained elevated for at least 6 wk, no IgG1 or IgE was detected. These results indicate that the type of immune responses to pDNA immunization in mice is strain dependent. Consequently, models for studying human allergen gene immunization require careful selection of suitable strains. In addition, this suggests that similar interindividual variation is likely in humans.

Activation of telomerase and its association with G1-phase of the cell cycle during UVB-induced skin tumorigenesis in SKH-1 hairless mouse

Telomerase is a ribonucleoprotein enzyme that adds hexanucleotide repeats TTAGGG to the ends of chromosomes. Telomerase activation is known to play a crucial role in cell-immortalization and carcinogenesis. Telomerase is shown to have a correlation with cell cycle progression, which is controlled by the regulation of cyclins, cyclin dependent kinases (cdks) and cyclin dependent kinase inhibitors (cdkis). Abnormal expression of these regulatory molecules may cause alterations in cell cycle with uncontrolled cell growth, a universal feature of neoplasia. Skin cancer is the most prevalent form of cancer in humans and the solar UV radiation is its major cause. Here, we investigated modulation in telomerase activity and protein expression of cell cycle regulatory molecules during the development of UVB-induced tumors in SKH-1 hairless mice. The mice were exposed to 180 mjoules/cm2 UVB radiation, thrice weekly for 24 weeks. The animals were sacrificed at 4 week intervals and the studies were performed in epidermis. Telomerase activity was barely detectable in the epidermis of non-irradiated mouse. UVB exposure resulted in a progressive increase in telomerase activity starting from the 4th week of exposure. The increased telomerase activity either persisted or further increased with the increased exposure. In papillomas and carcinomas the enzyme activity was comparable and was 45-fold higher than in the epidermis of control mice. Western blot analysis showed an upregulation in the protein expression of cyclin D1 and cyclin E and their regulatory subunits cdk4 and cdk2 during the course of UVB exposure and in papillomas and carcinomas. The protein expression of cdk6 and ckis viz. p16/Ink4A, p21/Waf1 and p27/Kip1 did not show any significant change in UVB exposed skin, but significant upregulation was observed both in papillomas and carcinomas. The results suggest that telomerase activation may be involved in UVB-induced tumorigenesis in mouse skin and that increased telomerase activity may be associated with G1 phase of the cell cycle.

Exogenous cysteamine increases basal pancreatic exocrine secretion in the rat

To determine whether exocrine pancreatic secretion is regulated by endogenous somatostatin, somatostatin deficiency was induced by cysteamine. Rats were subcutaneously administered a single dose of cysteamine (30 mg/100 g body weight) 12 hr before experiment. Anesthetized rats were prepared with cannulation into bile duct, pancreatic duct, duodenum, and jugular vein and pancreatic juice was collected. For in vitro study, isolated pancreata of rats, pretreated with cysteamine, were perfused with an intraarterial infusion of Krebs-Henseleit solution (37 degrees C) at 1.2 mL/min, and pancreatic juice was collected in 15-min samples. In vivo experiment of the rat, the mean basal pancreatic secretions, including volume, bicarbonate, and protein output were significantly increased from 18.4+/-0.5 microL/30 min, 0.58+/-0.05 microEq/30 min, and 214.0+/-26.1 microg/30 min to 51.6+/-3.7 microL/30 min, 1.52+/-0.11 microEq/30 min, and 569.8+/-128.9 microg/30 min, respectively (p<0.05). In the isolated perfused pancreas, cysteamine also resulted in a significant increase in basal pancreatic secretion (p<0.05). Simultaneous intraarterial infusion of octreotide (10 pmol/hr) to isolated pancreata partially reversed the effect of cysteamine on basal pancreatic secretion. These findings suggest that endogenous somatostatin play an important role on the regulation of basal pancreatic exocrine secretion.

Biliary papillary hyperplasia with clonorchiasis resembling cholangiocarcinoma

Infection by the liver fluke Clonorchis sinensis is very common in the Far East. It causes low grade inflammatory changes and proliferation in the biliary tree. Initially there is desquamation of the biliary epithelium, followed by hyperplasia and adenomatous proliferation. Cholangiocarcinomas are potential long term complications. We present a case of biliary papillary hyperplasia with clonorchiasis resembling cholangiocarcinoma in a 69-yr-old Korean man. Early recognition of biliary hyperplasia and treatment of Clonorchis sinensis is important to prevent development of cholangiocarcinoma, especially in the Far East.

Metastasis-induced acute pancreatitis in a patient with small cell carcinoma of the lung

Acute pancreatitis in cancer patients can be secondary to the malignant process itself or a complication of antineoplastic agent administration. However, acute pancreatitis caused by metastatic carcinoma of the pancreas is an uncommon condition with a poor prognosis. We report a case of a 63-year-old man with small cell carcinoma of the lung, who developed acute pancreatitis lately. Thirteen months earlier, he developed small cell carcinoma of the lung and received 6 cycles of chemotherapy. Abdominal CT scan showed swelling of the pancreas with multiple masses. The patient was managed conservatively and pancreatitis subsided. This case indicates that metastasis induced acute pancreatitis can be a manifestation of lung cancer, especially in small cell carcinoma.

Synthesis and evaluation of amino acid esters of 6-deoxypenciclovir as potential prodrugs of penciclovir

The amino acid ester derivatives of 6-deoxypenciclovir, 11-20, were synthesized as potential prodrugs of penciclovir, and were evaluated for their oral penciclovir bioavailability in mice and rats. Esterification of 6-deoxypenciclovir with N-carbobenzyl-oxyglycine, -L-alanine, -L-valine, -L-leucine, or -L-isoleucine (3.75equiv.) using conventional coupling method (DCC/DMAP) afforded the mono-O-ester derivatives 1-5 in 47-55% yields as a mixture of two diastereomers along with the di-O-ester derivatives 6-10 in 20-29% yields. Reductive cleavage of carbobenzyloxy (Cbz) group (10% Pd/C, 1 atmosphere of H2, room temperature in methanol) followed by subsequent treatment of the resulting free amine with methanolic HCI solution provided the mono-O-ester derivatives 11-15 as di-HCl salt in 51-98% yields and the di-O-ester derivatives 16-20 as tri-HCl salt in 65 98% yields. Of the prodrugs tested in mice and rats, 6-deoxypenciclovir O-L-valinate (13), O-L-isoleucinate (15), and O,O-di-glycinate (16) showed significantly higher urinary recovery of penciclovir compared with that of penciclovir, but those are somewhat lower than that of famciclovir.

Elevated serum levels of transforming growth factor-beta1 in patients with colorectal carcinoma: its association with tumor progression and its significant decrease after curative surgical resection

BACKGROUND

Transforming growth factor-beta1 (TGF-beta1) acts as a potent inhibitor of cell growth and tumor progression but loss of this negative regulation can contribute to tumor development. Some studies have reported an association between disease progression and TGF-beta1 expression in patients with colorectal carcinoma, but their results were not always consistent.

METHODS

Serum levels of TGF-beta1 were measured using an enzyme-linked immunoadsorbent assay in 121 consecutive patients with colorectal carcinoma and compared with TGF-beta1 serum levels in 31 healthy volunteers. Serum levels of TGF-beta1 also were measured in 50 patients who underwent curative surgical resection (part of the 121 preoperative patients) to compare their levels with preoperative serum levels of TGF-beta1.

RESULTS

Serum levels of TGF-beta1 in patients with colorectal carcinoma (45+/-15 ng/mL) (mean+/-the standard deviation) were significantly higher than those in the healthy control group (32+/-4 ng/mL) (P = 0.001). Serum levels of TGF-beta1 increased with increasing tumor stage (P < 0.01). Serum levels of TGF-beta1 were correlated significantly with depth of tumor invasion, lymph node metastasis, distant metastasis, and serum levels of carcinoembryonic antigen (CEA). Serum levels of TGF-beta1 tended to increase with increasing CEA (correlation coefficient = 0.21; P < 0.05). The mean serum level of TGF-beta1 in patients with colorectal carcinoma before surgery (45+/-14 ng/mL) (n = 50) significantly decreased to 34+/-7 ng/mL, which was within the normal range (32+/-4 ng/mL), after curative surgical resection of the tumor (P = 0.0000). Serum levels of TGF-beta1 after tumor resection decreased more significantly in patients with higher preoperative levels of TGF-beta1 (from 53+/-12 ng/mL to 36+/-6 ng/mL) (n = 30).

CONCLUSIONS

The results of the current study suggest that serum levels of TGF-beta1 in colorectal carcinoma patients may be associated with disease progression and may be used as a biomarker in the management of colorectal carcinoma patients. The authors believe further studies with a large number of patients for a longer follow-up period are necessary to conclude whether serum levels of TGF-beta1 carry significant clinical relevance.

Brain mapping in sedated infants and young children with passive-functional magnetic resonance imaging

Functional magnetic resonance imaging (fMRI) in pediatric patients presents a unique set of problems due to the need for patient compliance, the frequent need for sedation and an early developmental status. A new method for using fMRI in sedated infants and young children is presented using passive stimuli focused on visual, sensorimotor and language functions. All of these stimuli are presented such that no patient interaction is required. Eight sedated children undergoing diagnostic MRI scans of the brain participated in these passive fMRI procedures. Cortical regions were identified using standard techniques applied to the blood-oxygen-level-dependent signal which is the basis for fMRI. The results support the feasibility of brain mapping in sedated children with passive fMRI techniques.

Synthesis and evaluation of 2-amino-9-(1, 3-dihydroxy-2-propoxymethyl)- 6-fluoropurine mono- and diesters as potential prodrugs of ganciclovir

A series of 2-amino-9-(1,3-dihydroxy-2-propoxymethyl)-6-fluoropurine mono- and diesters, 6a-h, were synthesized as potential prodrugs of ganciclovir and evaluated for their oral ganciclovir bioavailability in rats. Treatment of 2-amino-6-chloro-9-(1, 3-dihydroxy-2-propoxymethyl)purine (4) with Me3N in DMF/THF (1/4) followed by the reaction of the resulting trimethylammonium chloride salt 5 with KF in DMF gave 2-amino-9-(1, 3-dihydroxy-2-propoxymethyl)-6-fluoropurine (2) in 83% yield. Esterification of 2 with an appropriate acid anhydride (Ac2O, (EtCO)2O, (n-PrCO)2O, or (i-PrCO)2O) (6 equiv for 6a-d or 1 equiv for 6e-h) in DMF in the presence of a catalytic amount of DMAP produced the diesters 6a-d in 92-98% yields and the monoesters 6e-h in 37-44% yields. Of the prodrugs tested in rats, the monoisobutyrate 6h achieved the highest ganciclovir bioavailability (45%) that is 15-fold higher than that from ganciclovir (3%), followed in order by the diisobutyrate 6d (42%), the diacetate 6a (41%), the monobutyrate 6g (41%), the monopropionate 6f (39%), the dipropionate 6b (35%), the dibutyrate 6c (35%), and the monoacetate 6e (29%). The prodrugs 6e-h were found to be quite stable at pH 6.0 (t1/2 = >29 days), 7.4 (t1/2 = >7 days), and 8.0 (t1/2 = >2 days) but had relatively short half-lives at pH 1.2 (t1/2 = 60-83 min).

Roles of acetyl-CoA carboxylase beta in muscle cell differentiation and in mitochondrial fatty acid oxidation

Acetyl-CoA carboxylase beta is expressed primarily in heart and skeletal muscle, where it may play a role in the control of mitochondrial fatty acid uptake and oxidation by controlling carnitine-palmitoyl-CoA transferase 1. To investigate the relationship between ACC-beta expression and myoblast differentiation, we specifically blocked ACC-beta production by expressing an antisense gene to the specific N-terminal region of ACC-beta in H9c2 cells. The expression of the antisense ACC-beta mRNA retarded cell fusion, myosin formation, and creatine kinase induction; all of these parameters are hallmarks of muscle cell differentiation. On the other hand, the rate of fatty acid oxidation was not affected by the presence or absence of ACC-beta in the cells.