Both extraneuronal monoamine transporter and O(6)-methylguanine-DNA methyltransferase expression influence the antitumor efficacy of 2-chloroethyl-3-sarcosinamide- 1-nitrosourea in human tumor xenografts.

We previously have found that 2-chloroethyl-3-sarcosinamide-1-nitrosourea (SarCNU) is a selective cytotoxin that enters cells via the extraneuronal transporter for monoamine transmitters (EMT). Both in vitro and in vivo studies demonstrated that SarCNU was more effective than BCNU against human gliomas. To clarify whether EMT expression correlates with antitumor efficacy of SarCNU, we determined human EMT (EMTh) and O(6)-methylguanine-DNA methyltransferase (MGMT) expression in nine human xenograft models using semiquantitative reverse-transcription polymerase chain reaction.

Aminohexanoic hydroxamate is a potent inducer of the differentiation of mouse neuroblastoma cells.

Deoxyhypusine synthase is the key enzyme for modifying a lysine residue to hypusine in the cellular protein eukaryotic initiation factor 5A (eIF-5A). Deletion of the deoxyhypusine synthase or the eIF-5A gene in yeast produces lethal phenotype. Inhibition of deoxyhypusine synthase by 1-guanidino-7-aminoheptane (GC7) suppresses tumor cell growth.

AMPK signaling in contracting human skeletal muscle: acetyl-CoA carboxylase and NO synthase phosphorylation.

AMP-activated protein kinase (AMPK) is a metabolic stress-sensing protein kinase responsible for coordinating metabolism and energy demand. In rodents, exercise accelerates fatty acid metabolism, enhances glucose uptake, and stimulates nitric oxide (NO) production in skeletal muscle. AMPK phosphorylates and inhibits acetyl-coenzyme A (CoA) carboxylase (ACC) and enhances GLUT-4 translocation.

The preclinical pharmacologic study of dopamine transporter imaging agent [99mTc]TRODAT-1.

The purpose of this study was to investigate the pharmacologic characteristics of TRODAT-1 (2beta-((N,N'-bis(2-mercaptoethyl)ethylene diamino)methyl), 3beta-(4-chlorophenyl)tropane) labeled with [99mTc] as an imaging agent for dopamine transporter (DAT). Radiochemical purity of [99mTc]TRODAT-1 was over 90%. The partition coefficients in octanol and buffer were 2.

Extraneuronal monoamine transporter expression and DNA repair vis-à-vis 2-chloroethyl-3-sarcosinamide-1-nitrosourea cytotoxicity in human tumor cell lines.

We previously found that 2-chloroethyl-3-sarcosin-amide-1-nitrosourea (SarCNU), a new chloroethylnitrosourea analogue presently in phase I clinical trials, is a selective cytotoxin that enters cells via the extraneuronal transporter for monoamine transmitters (EMT). In this study, we assessed whether EMT expression correlates with SarCNU cytotoxicity by determining EMT expression in 23 human tumor cell lines with reverse-transcription PCR. Western blot analysis was used to measure protein levels of the DNA repair genes, O6-methylguanine-DNA methyltransferase (MGMT), and excision repair cross-complementing rodent repair deficiency gene 2 (ERCC2).

Enhanced antitumor activity of sarCNU in comparison to BCNU in an extraneuronal monoamine transporter positive human glioma xenograft model.

A novel analogue of nitrosoureas, 2-chloroethyl-3-sarcosinamide-1-nitrosourea (SarCNU), has demonstrated increased anticancer effects in vitro and in vivo. Our previous work suggested that SarCNU enters cells via the extraneuronal monoamine transporter (EMT), that contributes to its enhanced cytotoxicity. In the present study, comparative activities of SarCNU and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) were evaluated in an EMT positive human glioma xenograft model.

Coupled vectors resolution method for chemometric calibration with three-way data.

A new second-order calibration procedure, the coupled vectors resolution (COVER) method, has been developed. The objective of the method is to seek a couple of vectors that minimize a least-squares criterion. With the knowledge indispensable for quantitation, the method yields direct solutions to various cases of second-order calibration.

Relationship between O6-methylguanine-DNA methyltransferase levels and clinical response induced by chloroethylnitrosourea therapy in glioma patients.

Background: Adjuvant nitrosourea chemotherapy fails to prolong survival significantly as many tumors demonstrate resistance to these drugs. It has been documented in cell lines that O6-methylguanine DNA methyltransferase (MGMT) plays an important role in chloroethylnitrosourea (CENU) drug resistance.

Methods: We evaluated MGMT expression in 22 glioma specimens by using an immunofluorescence assay and compared the results with clinical responses of the patients to CENU-based chemotherapy.

Pharmacology study of the neutral myocardial imaging agent technetium-99m-N(NOEt)2.

Objective: The biological properties of a new neutral myocardial imaging agent 99mTcN(NOEt)2 were evaluated.

Methods: Blood clearance in rabbits, biodistribution in rats, and initial myocardial imaging in dogs were performed.

Results: Radiochemical purity of 99mTcN(NOEt)2 was more than 90% and stable for 6 h at room temperature.

Dealing with energy demand: the AMP-activated protein kinase.

The AMP-activated protein kinase (AMPK) is a member of a metabolite-sensing protein kinase family that is found in all eukaryotes. AMPK activity is regulated by vigorous exercise, nutrient starvation and ischemia/hypoxia, and modulates many aspects of mammalian cell metabolism. The AMPK yeast homolog, Snf1p, plays a major role in adaption to glucose deprivation.

AMP-activated protein kinase phosphorylation of endothelial NO synthase.

The AMP-activated protein kinase (AMPK) in rat skeletal and cardiac muscle is activated by vigorous exercise and ischaemic stress. Under these conditions AMPK phosphorylates and inhibits acetyl-coenzyme A carboxylase causing increased oxidation of fatty acids. Here we show that AMPK co-immunoprecipitates with cardiac endothelial NO synthase (eNOS) and phosphorylates Ser-1177 in the presence of Ca2+-calmodulin (CaM) to activate eNOS both in vitro and during ischaemia in rat hearts.

Tubular epithelial-myofibroblast transdifferentiation in progressive tubulointerstitial fibrosis in 5/6 nephrectomized rats.

Background: Tubulointerstitial fibrosis is the final common pathway to end-stage renal failure. The present study investigated the potential role of tubular epithelial cells (TEC) in progressive fibrosis in the rat remnant kidney model.

Methods: Rats underwent 5/6 nephrectomy or a sham operation (control), and groups of six animals were killed at weeks 1, 3, 5, 9, 13, 17 and 21.

Green tea epigallocatechin gallate shows a pronounced growth inhibitory effect on cancerous cells but not on their normal counterparts.

(-)-Epigallocatechin gallate (EGCG), a catechin polyphenol compound, represents the main ingredient of green tea extract. Although EGCG has been shown to be growth inhibitory in a number of tumor cell lines, it is not clear whether the effect is cancer-specific. In this study we compared the effect of EGCG on the growth of SV40 virally transformed WI38 human fibroblasts (WI38VA) with that of normal WI38 cells.

Excision repair cross-complementing rodent repair deficiency gene 2 expression and chloroethylnitrosourea resistance in human glioma cell lines.

Objective: Nitrosoureas are the standard chemotherapeutic agents for malignant brain tumors. However, their anticancer effects are limited because many tumors are resistant to these agents. Nucleotide excision repair can repair bulky deoxyribonucleic acid adducts, including deoxyribonucleic acid damage induced by ultraviolet light and some chemotherapeutic agents, and may be implicated in nitrosoureas resistance.

Ligand- and DNA-induced dissociation of RXR tetramers.

Unliganded bacterially expressed RXR alpha lacking the N-terminal region AB (apo-RXR alpha delta AB) was found in solution as an apparent mixture of 165 kDa tetramers and 42 kDa monomers which could be quantitatively separated by gel filtration and non-denaturing gel electrophoresis. Under identical conditions both liganded (holo-) and apo-RAR alpha delta AB were present as single monomeric species. apo-RXR alpha delta AB tetramers, as well as dimers of the apo-RXR ligand binding domain (apo-LBD), dissociated readily into monomers when exposed to their cognate ligand 9-cis retinoic acid (9c-RA).

Effects of somatostatin analog on splanchnic hemodynamics and plasma glucagon level in portal hypertensive rats.

Aim: To investigate the effects of somatostatin analog on splanchnic hemodynamics and plasma glucagon level in portal hypertensive rats.

Methods: Twenty-eight male Sprague-Dawley rats were equally divided into a intrahepatic portal hypertension (IHPH) model group (n = 14, established by injection of CCl4) and a prehepatic portal hypertension (PHPH) model group (n = 14, established by stenosis of the portal vein). Animals in each group were subdivided into an octreotide treatment (injection) group and a control (normal saline injection) group.

Evidence for nucleotide excision repair as a modifying factor of O6-methylguanine-DNA methyltransferase-mediated innate chloroethylnitrosourea resistance in human tumor cell lines.

We examined the O6-methylguanine-DNA methyltransferase (MGMT) protein as well as MGMT activity levels and the excision repair cross-complementing rodent repair deficiency gene, ERCC2 (XPD), protein levels in 14 human tumor cell lines not selected for chloroethylnitrosourea (CENU) resistance. These results were compared with 1,3-bis-(2-chloroethyl)-1-nitrosourea (BCNU) cytotoxicity and UV light sensitivity. MGMT protein correlated significantly with MGMT activity (r = 0.

Acromegaly with normal basal growth hormone levels.

Background: The most common cause of acromegaly is excess of growth hormone (GH) secretion.

Methods: We report a 42-year-old male patient, who had become acromegalic over the past 5 years. There were no visual changes or change in sexual function, no gynaecomastia or galactorrhoea.

Marked elevation of hypusine formation activity on eukaryotic initiation factor 5A in v-HA-RAS transformed mouse NIH3T3 cells.

Hypusine formation on the eukaryotic initiation factor 5A (eIF-5A) precursor is ubiquitously present in eukaryotic cells and archebacteria. In this reaction, deoxyhypusine synthase catalyzes the conversion of one unique lysine residue on eIF-5A to deoxyhypusine using spermidine as the substrate. Hydroxylation of the deoxyhypusine residue completes hypusine formation on eIF-5A.

Dramatic attenuation of hypusine formation on eukaryotic initiation factor 5A during senescence of IMR-90 human diploid fibroblasts.

Deoxyhypusine synthase catalyzes the conversion of lysine to deoxyhypusine residue on the eukaryotic initiation factor 5A (elF-5A) precursor using spermidine as the substrate. Subsequent hydroxylation of the deoxyhypusine residue completes hypusine formation on elF-5A. Hypusine formation is one of the most specific polyamine-dependent biochemical events in eukaryotic cells.

Towards a bacteriorhodopsin-silicon neuromorphic photosensor.

We describe our efforts towards constructing a hybrid protein-silicon neuromorphic photosensor based on the photo-active protein bacteriohodopsin. This protein displays an differential photosensitivity similar to the response of the receptive field of an X-type retinal ganglion cell. Similar bacteriohodopsin photoelectrode arrays display inherent edge detection and motion enhancement.

Intracellular calcium ion responses to somatostatin in cells from human somatotroph adenomas.

Objective: Various GH secretory responses to long-acting somatostatin (SRIH) analogues have been observed during the treatment of acromegalic patients. The effects of SRIH on intracellular Ca2+ homeostasis in human somatotroph adenoma cells has not been examined in detail, and the underlying mechanisms therefore remain to be determined. Using isolated cells from human somatotroph adenomas, we have investigated the SRIH-induced intracellular Ca2+ responses at a single-cell level with computerized real time intracellular calcium ion (Ca2+i) imaging.

Quantitation of ERCC-2 gene expression in human tumor cell lines by reverse transcription-polymerase chain reaction in comparison to northern blot analysis.

Excision repair cross-complementing rodent repair deficiency genes (ERCC) are human genes implicated in nucleotide excision repair. ERCC-2 has been implicated in the repair of DNA damaged by chemotherapeutic agents, and may thus play an important role in anticancer drug resistance. ERCC-2 gene expression is low in primary tumor samples rendering it difficult to quantitate.

Effects of inhibitors of deoxyhypusine synthase on the differentiation of mouse neuroblastoma and erythroleukemia cells.

Deoxyhpusine synthase catalyzes the conversion of lysine to deoxyhypusine residue on the eukaryotic initiation factor 5A (eIF-5A) precursor using spermidine as the substrate. Subsequent hydroxylation of the deoxyhypusine residue completes hypusine formation on eIF-5A. Polyamines (putrescine, spermidine, and spermine) have been implicated in tumor growth and differentiation.

Correlation of chloroethylnitrosourea resistance with ERCC-2 expression in human tumor cell lines as determined by quantitative competitive polymerase chain reaction.

We have developed a method to quantitate ERCC-2 gene expression in tumor cell lines. A mutant ERCC-2 DNA fragment (1-bp mutation) is used as a competitive DNA template in a coamplification PCR reaction with cDNA obtained by reverse transcribing DNase-free total RNA from six human tumor cell lines. The PCR products are separated on agarose gel by virtue of their differential banding pattern upon restriction enzyme digestion.