Design, synthesis, and biological evaluation of aromatic ester prodrugs of 1-(3'-hydroxypropyl)-2-methyl-3-hydroxypyridin-4-one (CP41) as orally active iron chelators

In order to improve chelation efficacy and to minimise toxicity, eleven aromatic ester prodrugs of 1-(3'-hydroxypropyl)-2-methyl-3-hydroxypyridin-4-one (CP41) have been synthesised. The distribution coefficients of these ester prodrugs between 1-octanol and MOPS buffer pH 7.4 were measured together with their rates of hydrolysis at pH 2 and pH 7.4, in rat blood and liver homogenate. The biliary metabolic profiles of selected ester prodrugs were investigated in rats. The in vivo iron mobilisation efficacy of these ester prodrugs has been compared with that of the parent drug using a 59Fe-ferritin loaded rat model. The hydrolytic rates of these esters vary appreciably, esters with heteroaromatic acid moieties being less stable than the corresponding benzoyl analogues. Many prodrugs were found to enhance the ability of the parent hydroxypyridinone to facilitate 59Fe excretion, the optimal effect being observed with the 4-methylbenzoyl ester derivative 8d. However, not all prodrugs provide an increased efficacy, indicating that lipophilicity is not the only factor which influences drug efficacy. Furthermore no clear correlation between lipophilicity, susceptibility towards hydrolysis and efficacy was detected.

Design, synthesis and evaluation of N-basic substituted 3-hydroxypyridin-4-ones: orally active iron chelators with lysosomotrophic potential

To investigate the possibility of targeting chelators into the lysosomal iron pool, nine bidentate 3-hydroxypyridin-4-ones with basic chains have been synthesized. As the turnover of ferritin iron is centred in the lysosome, such strategy is predicted to increase chelator efficacy of bidentate ligands. The pKa values of the ligands together with their distribution coefficients between 1-octanol and 4-morpholinepropane sulphonic acid (MOPS) buffer pH 7.4 have been determined. The in-vivo iron mobilization efficacy of these basic 3-hydroxypyridin-4-ones has been investigated in a 59Fe-ferritin-loaded rat model. No obvious correlation was observed between efficacy and the pKa value of the side chain, although those with pKa > 7.0 tended to be more efficient than those with pKa < 7.0. The imidazole-containing molecules are much less effective than the tertiary amine derivatives. A dose-response study suggested that basic pyridinones are relatively more effective at lower doses when compared with N-alkyl hydroxypyridinones. Optimal effects were observed with the piperidine derivatives 4h and 4i. The derivative 4i at a dose of 150 micromol kg(-1) was more effective than 450 micromol kg(-1) deferiprone, the widely adopted clinical dose.

Liquid extraction and ion-pair HPLC for determination of hydrophilic 3-hydroxypyridin-4-one iron chelators

Hydrophilic 3-hydroxypyridin-4-ones (HPOs), such as 1-(2'-carboxyethyl)-2-methyl-3-hydroxypyridin-4-one (CP38), 1-(3'-hydroxypropyl)-2-methyl-3-hydroxypyridin-4-one (CP41) and 1-(2'-hydroxyethyl)-2-ethyl-3-hydroxypyridin-4-one (CP102), are orally active iron chelators and ester prodrugs of these molecules are currently under investigation. A liquid extraction method using acetonitrile and 2-propanol (80:20 v/v) under acidic and NaCl-saturated conditions has been developed in order to efficiently extract these HPOs from various matrices. The extracted HPOs were determined using a reversed phase polymer HPLC column (PLRP-S 100 A) and the gradient ion-pair mobile phase containing tetrabutylammonium chloride (5 mM) and EDTA (0.5 mM). The extraction recovery of these chelators in phosphate buffer, rat blood and liver homogenate varied from 85 to 94%. The coefficients of variation (C.V.) for within-day determination were in the range of 1.4-3.3% at 1 mM and 2.0-4.7% at 0.1 mM. High accuracy of determination was also achieved.

Synthesis, physicochemical characterization, and biological evaluation of 2-(1'-hydroxyalkyl)-3-hydroxypyridin-4-ones: novel iron chelators with enhanced pFe(3+) values

The synthesis of a range of 2-(1'-hydroxyalkyl)-3-hydroxypyridin-4-ones as bidentate iron(III) chelators with potential for oral administration is described. The pK(a) values of the ligands and the stability constants of their iron(III) complexes have been determined. Results indicate that the introduction of a 1'-hydroxyalkyl group at the 2-position leads to a significant improvement in the pFe(3+) values. Such an effect was found to be greater with the hydroxyethyl substituent than with the hydroxymethyl substituent, particularly in the cases of 1-ethyl-2-(1'-hydroxyethyl)-3-hydroxypyridin-4-one (pFe(3+) = 21.4) and 1,6-dimethyl-2-(1'-hydroxyethyl)-3-hydroxypyridin-4-one (pFe(3+) = 21.5) where an enhancement on pFe(3+) values in the region of two orders of magnitude is observed, as compared with Deferiprone (1, 2-dimethyl-3-hydroxypyridin-4-one) (pFe(3+) = 19.4). The ability of these novel 3-hydroxypyridin-4-ones to facilitate the iron excretion in bile was investigated using a [(59)Fe]ferritin-loaded rat model. Chelators and prodrug chelators possessing high pFe(3+) values show great promise in their ability to remove iron under in vivo conditions.

Observation of Multi-TeV Gamma Rays from the Crab Nebula using the Tibet Air Shower Array

The Tibet experiment, operating at Yangbajing (4300 m above sea level), is the lowest energy air shower array, and the new high-density array constructed in 1996 is sensitive to gamma-ray air showers at energies as low as 3 TeV. With this new array, the Crab Nebula was observed in multi-TeV gamma-rays and a signal was detected at the 5.5 sigma level. We also obtained the energy spectrum of gamma-rays in the energy region above 3 TeV which partially overlaps those observed with imaging atmospheric Cerenkov telescopes. The Crab spectrum observed in this energy region can be represented by the power-law fit dJ&parl0;E&parr0;&solm0;dE=&parl0;4.61+/-0.90&parr0;x10-12&parl0;E&solm0;3 TeV&parr0;-2.62+/-0.17 cm-2 s-1 TeV-1. This is the first observation of gamma-ray signals from point sources with a conventional air shower array using scintillation detectors.

Predominant germ-line mutation of the hMSH2 gene in Japanese hereditary non-polyposis colorectal cancer kindreds

By means of PCR-SSCP and direct sequencing, we detected 12 germ-line mutations of hMSH2 or hMLH1 in 37 Japanese hereditary non-polyposis colorectal cancer (HNPCC) kindreds, of whom 15 satisfied the Amsterdam and 22 the Japanese criteria. The germ-line mutation detection rate of hMSH2 was much higher than that of hMLH1 (11/37 vs. 1/37). The total mutation detection rate of hMSH2 and hMLH1 in the Amsterdam criteria group was significantly higher than that in the Japanese criteria group (9/15 vs. 3/22). Furthermore, the mean age of the HNPCC patients in the mutation-positive group was lower than that in the mutation-negative one; the rates of both vertical transmission and multiplicity of tumors in the mutation-positive group were higher than those in the mutation-negative one. In addition, the number of patients with microsatellite instability-positive cancers in the mutation-positive group was higher than that in the mutation-negative one. Our results suggest firstly that the hMSH2 gene plays a much more important role than hMLH1 in the carcinogenesis of Japanese HNPCC patients, secondly that the rate of hMSH2 and hMLH1 mutations is high in the kindreds satisfying the Amsterdam criteria and thirdly that both the clinical phenotypes (early onset, vertical transmission and multiplicity of tumors) and the microsatellite instability status are important for the genetic screening of HNPCC.

Gradient ion-pair high-performance liquid chromatographic method for analysis of 3-hydroxypyridin-4-one iron chelators

A gradient ion-pair HPLC separation of highly hydrophilic 3-hydroxypyridin-4-one (HPO) iron chelators is described. The separation of HPOs was performed using a reversed-phase polymer HPLC column (PLRP-S 100 A, 15x0.46 cm ID, 5 microm). The ion-pair buffer contained 1-heptanesulfonic acid (sodium salt) (5 mM) and the pH was adjusted to 2.0 using HCl. The gradient was 2%-35% CH3CN in 20 min and post-run was followed for 5 min using 2% CH3CN and 98% buffer. The flow-rate was 1 ml/min and the analytes were monitored at 280 nm. The retention times of 30 hydrophilic HPOs fell in the range of 10-18 min with sharp peak shapes, although these iron chelators possess various functional groups and distribution coefficients. The application of this HPLC method in the analysis of HPO chelators and their metabolites in rat bile and urine is described.

Two divergent signaling pathways for TGF-beta separated by a mutation of its type II receptor gene

Transforming growth factor beta (TGF-beta) can inhibit epithelial cell growth and induce extracellular matrix formation through signal transduction via its two receptors and its downstream intracellular Smad proteins. We recently reported a germline mutation, i.e., substitution of methionine for threonine at codon 315 in the kinase subdomain IV, of the TGF-beta type II receptor gene in a kindred of hereditary nonpolyposis colorectal cancer without microsatellite instability and found that the mutant receptor abolished the signal transduction for growth inhibition by TGF-beta. In this study, we performed further functional analysis of this mutant receptor. The results showed that, in contrast to its failure to mediate growth inhibition by TGF-beta, the mutant receptor still retained the ability to induce one of the extracellular matrix proteins, plasminogen activator inhibitor type 1, upon TGF-beta treatment. However, coincident with its failure to mediate growth inhibition by TGF-beta, the mutant receptor failed to transcriptionally upregulate one of the cyclin-dependent kinase inhibitors, p15(INK4B), in response to TGF-beta. These data suggest that threonine 315 of the TGF-beta type II receptor is dispensable for extracellular matrix protein production, but is essential for the growth inhibition by TGF-beta, and that the lack of growth inhibition due to the mutant receptor is possibly mediated through its failure to upregulate p15(INK4B).

Synthesis, physicochemical properties and biological evaluation of aromatic ester prodrugs of 1-(2'-hydroxyethyl)-2-ethyl-3-hydroxypyridin-4-one (CP102): orally active iron chelators with clinical potential

The synthesis of seven aromatic ester derivatives of 1-(2'-hydroxyethyl)-2-ethyl-3-hydroxypyridin-4-one is described. These ester prodrugs have been designed to target iron chelators to the liver, the major iron storage organ. In principle this should improve chelation efficacy and minimize toxicity. The distribution coefficients of these ester prodrugs between 1-octanol and MOPS buffer pH 7.4 were measured together with their rates of hydrolysis at pH 2 and pH 7.4, in rat blood and liver homogenate. Esters with heteroaromatic acid moieties were found to be less stable than benzoyl analogues. The in-vivo iron mobilisation efficacy of these ester prodrugs has been compared with that of the parent drug using a 59Fe-ferritin loaded rat model. Many prodrugs were found to enhance the ability of the parent hydroxypyridinone to facilitate 59Fe excretion. However, not all prodrugs provided increased efficacy, demonstrating that lipophilicity is not the only factor which influences drug efficacy. Furthermore, no clear correlation between efficacy and susceptibility to hydrolysis was detected. The picolinic and nicotinic ester derivatives appear to offer the best potential as prodrugs as they have a relatively low LogP value and yet lead to enhanced efficacy over the parent hydroxypyridinone.

In vivo iron mobilisation evaluation of hydroxypyridinones in 59Fe-ferritin-loaded rat model

Although there are a number of well-characterised animal models available for testing and comparing the efficacy of iron chelators, most are expensive to operate and are not capable of providing rapid and reproducible results. The method described herein is based on the labelling of rat liver with 59Fe using rat 59Fe-ferritin. This method produces highly reproducible data of the type necessary for dose-response investigations, comparison of the efficacies of different administration routes, and structure activity studies.

The development of nao li shen and its clinical application

The traditional Chinese medicine Nao Li Shen (containing ginseng, gastrodia tuber, chuanxiong rhizome and red sage root) is used in craniocerebral injury, cervical spondylosis and cerebrovascular diseases. The preparation, as an orally administered liquid, was tested in Mongolian gerbils and shown to increase tolerance to ischaemia and anoxia. Clinical use of the preparation resulted in improvement in 96% of 202 patients, as judged by right cerebral blood flow, TCD and CT examination. We conclude that Nao Li Shen has a positive curative effect upon craniocerebral injury and sequelae of cerebrovascular diseases.

Genomic structure of the transforming growth factor beta type II receptor gene and its mutations in hereditary nonpolyposis colorectal cancers

To characterize the tumorigenetic role of the transforming growth factor beta type II receptor (RII) gene, we defined its genomic structure, which consists of seven exons. The sequences of exon-intron junctions were determined to facilitate mutation analysis of each exon. Twenty-five carcinomas and five adenomas from hereditary nonpolyposis colorectal cancer patients were analyzed for mutations in the entire coding region. Four missense mutations (two in adenomas and two in carcinomas) were found in the 10 cases carrying the polyadenine deletions in one allele. These results indicate that RII shares the two-hit inactivation mechanism with tumor suppressor genes and that mutations of it may occur in the early stage of tumorigenesis.

Loss or somatic mutations of hMSH2 occur in hereditary nonpolyposis colorectal cancers with hMSH2 germline mutations

Hereditary nonpolyposis colorectal cancer (HNPCC) is a major cancer susceptibility syndrome known to be caused by the inheritance of mutations in DNA mismatch repair genes, such as hMSH2, hMLH1, hPMS1 and hPMS2. To investigate the role of genetic alterations of hMSH2 in HNPCC tumorigenesis, we analyzed 36 Japanese HNPCC kindreds as to hMSH2 germline mutations. Moreover, we also examined somatic mutations of hMSH2 or loss of heterozygosity at or near the hMSH2 locus in the tumors from the hMSH2-related kindreds. Germline mutations were detected in five HNPCC kindreds (5/36, 14%). Among them, three were nonsense mutations, one was a frameshift mutation and the other was a mutation in an intron where the mutation affected splicing. Loss of heterozygosity in four and somatic mutations in one were detected among the eight tumors with hMSH2 germline mutations. All these alterations were only detected in genomic instability(+) tumors, i.e., not in genomic instability(-) ones, indicating that mutations of hMSH2 were responsible for at least some of the tumors with genomic instability. These data establish a basis for the presymptomatic diagnosis of HNPCC patients, and constitute further evidence that both DNA mismatch repair genes and tumor suppressor genes may share the same requirement, i.e., two hits are necessary to inactivate the gene function.

Mutations of the transforming growth factor-beta type II receptor gene and genomic instability in hereditary nonpolyposis colorectal cancer

To determine the relation between the mutation of the TGF-beta type II receptor gene and genomic instability in the tumorigenesis of hereditary nonpolyposis colorectal cancer (HNPCC), we screened genomic DNA of 38 tumors from 25 HNPCC patients, 15 colorectal cancers from familial adenomatous polyposis patients, and 8 sporadic endometrial cancers, in two areas containing a (A)10 repeat or a (GT)3 repeat of the gene. Seventeen of the 24 (71%) genomic instability-positive HNPCC tumors carried one or two A deletions in the (A)10 repeat, while none of the 14 genomic instability-negative tumors did. These deletions inactivate the receptor through a frameshift mutation and the resultant protein truncation. No mutation was detected in the (GT)3 repeat sequence, but we found a missense mutation of codon 537 in the same area in one tumor. One A deletion was also detected in a genomic instability-positive sporadic endometrial cancer, but none in familial adenomatous polyposis tumors. No mutations were detected in the corresponding normal cells of these cases, indicating a somatic mutation. These data suggest that the TGF-beta type II receptor gene is a major target of genomic instability in HNPCC tumorigenesis.

[Effect of arginine supplementation on T-lymphocyte function in burn patients]

It is well accepted that nutritional support improves the immunologic functions in burn patients. Arginine has been demonstrated to have tissue--specific properties which influence certain components of the immune system. A series of experiments were carried out in this study, in order to evaluate the immune effect of arginine on T lymphocyte functions in burn patients. Two groups of burn patients with comparable clinical protocol receiving same nutritional administration except the amount of arginine in the nutrients were studied. In one group, 2% of energy supplied by arginine was added in their nutrients, while, the control group received 2% of energy from amino acid compounds instead. The T lymphocyte immune parameters were determined on days 3, 7, 14, 21 and 28 postburn. The data showed that the 2% of total energy supplied by arginine was found to significantly enhance the T lymphocyte response to PHA, CD4 phenotype expression, CD4/CD8 ratio, IL-2 production and IL-2 receptor expression, as compared with the control group. It suggests arginine should become one of the most important nutrients supplied to burn patients.

[The depressive disorder in burn patients]

The CES-D, HAMD and ABSH scales were used to assess the incidence of depressive disorder in 30 burn patients during hospitalization and in 26 patients after they re-entered the society. The results indicated that the occurrence of depressive symptoms (70%) and depression (40%) in hospitalized burn patients increased significantly as compared to the control group and a group of surgical patients. Furthermore, 30 burn patients were divided into three groups according to the extent and the site of their burns, and it was found that the incidence of depressive symptoms and the degree of depressive reaction both in group I (TBSA = 55.44 +/- 22.09%) and group III (TBSA = 6.03 +/- 6.03%, with electrical injury, facial burn, hot roller injury) were significantly higher than those in group II (TBSA = 5.49 +/- 4.19%), but there was no statistical difference between group I and group III. The incidence of depressive symptoms assessed by the CES-D scale in burn patients after they re-entered the society increased obviously as compared with normal control (46.15% vs. 10%). Furthermore, there was a negative correlation between CES-D scores andse. ABSH scorThe CES-D score was also found to be negatively correlated to the scores in four aspects (physical, mental, social and general) in ABSH scale. We conclude that burn injuries can complicate the depressive disorder. Cosmetic deformity and loss of function may be the main causes of the increase in the incidence of depressive disorder during hospitalization, while the occurrence of depressive disorder when they re-entered the society may be related to physical disabilities, mental status and social adaptability.

[Changes in plasma immunologic reactive beta-endorphin and their effect on lymphocyte response to phytohemagglutinin after thermal injury]

The study of immunosuppression after thermal injury has aroused great interest. The present study is an investigation of changes of plasma ir-beta EP in patients and their effect on lymphocyte responses to PHA following thermal injury, in order to establish a relationship between the immune and neuroendocrine system. Plasma ir-beta EP in eighteen burn patients was determined using the radioimmunoassay. At the same time, autoplasma and the autoplasma treated with anti-beta EP serum had been both tested for their effect on lymphocyte responses to PHA. The levels of plasma ir-beta EP were found to be elevated significantly in every phases during the first three days postburn (P < 0.0005-P < 0.001), and then declined to the normal level on the fourth or fifth day postburn. The lymphocytes cultured with autoplasma showed their inhibited responses to PHA during the first three days postburn and returned to normal on the fourth or fifth day postburn, while the autoplasma treated with anti-beta EP serum had an effect to improve the lymphocyte responses to PHA. The findings suggest that burn stress is a strong stimulation which may elevate plasma ir-beta EP and which in turn decrease the lymphocyte response to PHA. We assume that increased plasma ir-beta EP may be one of the main causes of immunosuppression after thermal injury.

Clinical application of a patient-controlled apparatus for ventricular administration of morphine in intractable pain: report of 28 cases

The authors developed a patient-controlled apparatus (L-224) for ventricular administration of pain-relieving medication and utilized it in the treatment of 28 patients with intractable pain. The initial dose of morphine hydrochloride was 1 mg, which afforded pain relief for an average of 170 hours. At an average dose of 1.8 mg, the average time of pain relief obtained was 137 hours. Therefore, they conclude that L-224 is a satisfactory apparatus for the ventricular administration of pain medication; it is patient controlled, safe, and reliable in clinical application.

Immunocytochemical and electron microscopic study of hepatitis B virus antigen and complete particle production in hepatitis B virus DNA transfected HepG2 cells

The relationship between the presence of hepatitis B virus antigens, their localization and hepatitis B virus replication was studied in different clones of cultured HepG2 hepatoblastoma cells transfected with cloned hepatitis B virus DNA. Intracellular hepatitis B virus antigens were detected by immunofluorescence. The production of these antigens was evaluated in the culture media by enzyme-linked immunoassay. Hepatitis B virus DNA was detected using dot-blot hybridization. Three types of HBcAg staining were observed in transfected HepG2 cells: (a) cells with nuclear HBcAg, (b) cells with cytoplasmic HBcAg and (c) cells with both nuclear and cytoplasmic HBcAg. Cell types b and c also expressed hepatitis B virus DNA in their culture media. Our results suggest that cytoplasmic HBcAg may be more involved than nuclear HBcAg in hepatitis B virus replication. The site of hepatitis B virus formation in hepatocytes was studied by electron microscopic examination of a specific hepatitis B virus producer clone, thereby allowing detection of intracellular Dane particles more easily than liver biopsy samples from infected patients. Dane particles and HBsAg filaments were found in large, dilated structures probably related to the endoplasmic reticulum. Budding of core particles into cisternae of endoplasmic reticulum-related structures appears to be a possible mechanism for hepatitis B virus formation; our results suggest that the exocytosis of cisternae to extracellular spaces may be a mechanism for release of hepatitis B virus particles.

Selection of a Brucella vaccine strain of low residual virulence by chemical mutagenesis

Following incubation of the oral vaccine Brucella suis strain 2 with diethyl sulphate (DES), a mutant designated strain S105 was selected by screening surviving bacteria for reduced virulence for mice. Strain 105 also showed low residual virulence for guinea-pigs and, unlike the parent strain, did not initiate abortion in pregnant sheep and goats after parenteral administration. Nevertheless, it was as effective as the parent strain in stimulating protective immunity to Brucella melitensis when given as an oral vaccine to sheep under both experimental and field conditions.

Retinal adaptation effects on the patterned VEP and ERG

The patterned visually evoked potential (pVEP) and patterned electroretinogram (pERG) after light and dark adaptation were investigated in 10 visually normal human observers. The influence of retinal preadaptation on the pVEP appeared to be dependent on the stimulus field size. With a 6 degree field size retinal adaptation effects were not apparent, but with a 12 degree field size the amplitudes of the dark-adapted steady-state pVEP (ssVEP) and transient pVEP (tVEP) were significantly larger than the light-adapted amplitudes. Similarly pERG's elicited by a 12 degree field size produced larger amplitude dark-adapted results. The implications of these findings are discussed. Monitoring the temporal changes in the pVEP subsequent to different retinal preadaptation levels proved to be inconclusive for the conditions studied.