Elevation of c-myc transcript level in human liver during surgical resection of hepatocellular carcinoma: possible cause for underestimation of c-myc gene activation in the tumor

It has been a matter of controversy as to whether c-myc gene expression is activated in human hepatocellular carcinoma (HCC). We observed that the c-myc mRNA level in HCC was similar to that of the adjacent non-cancerous portion, as determined in freshly obtained specimens after a partial liver resection. However, the c-myc transcript was at a low level in non-cancerous tissue which was biopsied prior to surgery, whereas it was still at a high level in HCC obtained without performing hepatectomy. These results suggest that the high transcript level observed in the non-cancerous tissue from the excised liver relates to liver resection itself, and that the c-myc gene expression is enhanced in the HCC.

Expression of c-myc oncogene in colorectal polyps as a biological marker for monitoring malignant potential

The expression of oncogenes (c-myc, c-fos, c-Ki-ras, c-Ha-ras, and p53) was examined by Northern blot analysis using freshly isolated human colorectal and gastric cancers and noncancerous portions as the controls. Remarkably high levels of c-myc expression were found in colorectal cancers (eight of 11), but not in gastric cancers. High levels of c-myc expression were also detected in colorectal polyps and in metastatic liver tumors. In colorectal polyps, the transcript levels significantly correlated with the histologic malignancy and the size. In contrast, neither c-fos nor c-Ki-ras was overexpressed in colorectal and gastric cancers, and transcripts of c-Ha-ras and p53 were not evident in any tissue examined. In light of these observations the c-myc expression may be specifically associated with the evolution of colorectal cancer as well as progression and maintenance stages, hence may prove to be a useful marker to evaluate the malignant potential of colorectal polyps.

Human diabetes associated with a deletion of the tyrosine kinase domain of the insulin receptor

The insulin receptor has an intrinsic tyrosine kinase activity that is essential for signal transduction. A mutant insulin receptor gene lacking almost the entire kinase domain has been identified in an individual with type A insulin resistance and acanthosis nigricans. Insulin binding to the erythrocytes or cultured fibroblasts from this individual was normal. However receptor autophosphorylation and tyrosine kinase activity toward an exogenous substrate were reduced in partially purified insulin receptors from the proband's lymphocytes that had been transformed by Epstein-Barr virus. The insulin resistance associated with this mutated gene was inherited by the proband from her mother as an apparently autosomal dominant trait. Thus a deletion in one allele of the insulin receptor gene may be at least partly responsible for some instances of insulin-resistant diabetes.

Familial type C syndrome of insulin resistance and short stature with possible autosomal dominant transmission

We describe a 17-yr-old girl with insulin resistant diabetes, acanthosis nigricans, hirsutism and short stature. At the age of 14 she was found to have glycosuria and diagnosed as diabetes mellitus. No endocrinological abnormality except transient amenorrhea and exaggerated LH response to LHRH was found. Insulin resistance was demonstrated by fasting hyperinsulinemia, insulin tolerance test and euglycemic glucose clamp test, and large doses of insulin with CSII were not effective in controlling blood glucose. Insulin binding to erythrocytes was normal, suggesting a postbinding defect. The same phenotype of insulin resistant diabetes and short stature was found in her mother who was diagnosed as diabetes mellitus at the age of 31 and died of diabetic nephropathy at the age of 41. Her maternal grandfather and uncle were reportedly affected with the same phenotype. Her father had impaired glucose tolerance, but no hyperinsulinemia. Two sisters had essentially normal glucose tolerance. Insulin binding to erythrocytes of her father and mother was also in the normal range. These results suggest that the present case may be a rare syndrome present together with type C syndrome of insulin resistance, and with short stature which was inherited autosomal dominantly.

Comparison of rotational speeds and torque properties between air-bearing and ball-bearing air-turbine handpieces

We examined the effects of air pressure on the free-running speed of air-bearing and torque-type ball-bearing air-turbine handpieces. The air pressure for the former should be kept at a certain high level to maintain the stable super-thin air-bearing film and to provide the quasi-constant speed of around 420,000 to 480,000 rpm. On the other hand, the air pressure for the latter could be adjusted to provide some varieties of speeds, ranging from about 150,000 to 320,000 rpm. Subsequently, to compare torque properties and cutting effectiveness between these two handpieces, weight-load cutting tests were conducted, using a glass-ceramic workpiece and a commercial diamond point. It was confirmed that the air-bearing handpiece had the lower torque power but exhibited better cutting effectiveness, compared with its counterpart.

Tissue-differential expression of two distinct genes for phosphoribosyl pyrophosphate synthetase and existence of the testis-specific transcript

Cloning of cDNA coding for rat phosphoribosyl pyrophosphate (PPRibP) synthetase (EC 2.7.6.1) revealed two distinct types of subunit, referred to as PRS I and PRS II (Taira et al. (1987) J. Biol. Chem. 262, 14867-14870). Tissue-specific expression of PRS I and PRS II genes (designated PRPS1 and PRPS2, respectively), was shown for 16 rat organs, using Northern blot analysis. The 2.3 kb PRPS1 mRNA level was high in the brain and adrenal gland, whereas the 3.7 kb PRPS2 mRNA level prevailed in the lung and spleen. Both genes were highly expressed in the thymus, adipose tissue and testis. In other mammals (mouse, calf and human), these two types of mRNA were also detected in various tissues and cell lines. Thus, the expression of each gene is regulated in a tissue-specific manner and there may be functional differences between catalytic and/or regulatory properties of subunits PRS I and II of this enzyme. In the testis, an additional PRPS1-related transcript of 1.4 kb was noted in rats, mice and humans. This transcript may belong to a group of testis-specific gene expressions or functions.

Molecular cloning and sequencing of human cDNA for phosphoribosyl pyrophosphate synthetase subunit II

cDNA clones for human phosphoribosyl pyrophosphate synthetase subunit II (PRS II) were isolated. The five overlapping clones contained 2457 base pairs (bp) covering a 954-bp complete coding region for 318 amino acid residues. Homologies between human and rat PRS II were 99% of the amino acids and 88% of the nucleotides in the coding region. This amino acid homology seems to be the highest so far reported for enzymes involved in nucleotide metabolism and glycolysis. The highly conserved structure may be required for unique catalysis and rigid regulation of this enzyme.

Studies of Ti alloys for dental castings

Casting of Ti has been recently investigated in dentistry. The purpose of this study was to examine the alloying effect on the cast Ti. Metallurgical structures, mechanical properties, and in vitro corrosion resistance were, therefore, studied for cast Ti and for four selected cast Ti alloys such as Ti-6AI-4V, Ti-15V, Ti-20Cu, and Ti-30Pd. A "Castmatic" dental casting machine was utilized, which involved argon-arc melting and subsequent argon/vacuum-pressurized casting. The photomicrographs revealed quite large grains in the cast structures. XRD analyses on cast Ti metals showed the quasi-equilibrium phases present. The strength of cast Ti could be significantly increased by alloying. Cross-sectional microhardness measurements of cast Ti alloys showed U-type hardness distribution due to the surface mold reaction. All the cast Ti alloys examined showed a strong passivity trend in the corrosion test. The present results suggest that cast Ti alloys have promising features for future dental uses.

Localization of human phosphoribosylpyrophosphate synthetase subunit I and II genes (PRPS1 and PRPS2) to different regions of the X chromosome and assignment of two PRPS1-related genes to autosomes

Complementary DNA clones for phosphoribosylpyrophosphate synthetase subunits I and II (PRS I and PRS II) were used to determine the chromosomal localization of the corresponding human genes. Southern blot analysis of genomic DNAs isolated from human placenta and a panel of human-mouse somatic cell hybrids revealed that the rat PRS I cDNA probe detected at least five human specific DNA segments (23, 20, 14.5, 6.7, and 4.3 kb) in BamHI digests. The 23-, 14.5-, and 6.7-kb DNA segments were detected only if the hybrids contained human chromosome X or translocation chromosome 7p+ (7qter greater than 7p22::Xq21 greater than Xqter), indicating the location of these segments to Xq21-qter (PRPS1). The 20- and 4.3-kb DNA segments did not cosegregate with the other three segments, and spot blot hybridization analysis using flow-sorted human chromosomes indicated that these are the PRPS1-related genes (PRPS1L1 and PRPS1L2) and could be assigned to chromosomes 7 and 9, respectively. The human-specific PRS II cDNA probe revealed a BamHI DNA segment (17 kb), which segregated condordantly with the X chromosome but not with the PRPS1 gene. We surmise that the gene for PRS II (PRPS2) is located at a different region of the X chromosome, namely Xpter-a21.

Single-unit activity in bulbar reticular formation during food ingestion in chronic cats

1. Single-unit activity was recorded from 215 neurons in the medial bulbar reticular formation during the masticatory sequence, from intake to deglutition, of 3 kinds of food (cat food pellets, canned fish, and milk) in 8 chronically prepared, unanesthetized, spontaneously respiring cats with their head fixed to a stereotaxic apparatus without pain or pressure. The firing patterns were compared to the simultaneously recorded EMGs of the jaw-closing and -opening muscles and to the jaw movement. 2. Fifty neurons changed their firing patterns during mastication. Nine neurons increased and one neuron decreased or stopped firing coincident with the masticatory sequence without an apparent rhythmical modulation of frequency corresponding with the masticatory rhythm (nonphasic group). The firing pattern of the remaining 40 neurons was modulated in phase with jaw movement (phasic group); 34 neurons either showed a spike burst or attained the highest firing frequency during the jaw-opening phase (opening type), while 6 neurons did so during the jaw-closing phase (closing type). The firing patterns of each neuron were essentially the same regardless of the kind of food ingested, except for 2 opening-type neurons that showed a rhythmical burst during mastication of solid food and tonic activity during lapping milk. 3. For 16 phasic neurons, there were significant correlations between some aspects of the firing pattern and a parameter of the movement during ingestion of solid food and/or milk. With one exception, these relationships did not appear to be due to sensory feedback. 4. We detected a monosynaptic excitatory projection from 3 opening-type neurons to the anterior digastric motoneurons, and monosynaptic inhibitory projections to the temporal or masseter motoneurons from 3 other opening-type neurons, by spike-triggered averaging of the full-wave rectified EMG of the jaw-closing and -opening muscles. No monosynaptic projections from the closing-type neurons or nonphasic group neurons to either jaw-opener or -closer motoneurons were detected. 5. The instantaneous firing frequency of all 3 inhibitor premotor neurons was positively correlated with the opening velocity, and the firing of 2 was also related to the jaw displacement.(ABSTRACT TRUNCATED AT 400 WORDS)

First-phase insulin response to glucose in nonobese or obese subjects with glucose intolerance: analysis by C-peptide secretion rate

This study was proposed to clarify the impairment of first-phase insulin response to glucose in subjects with glucose intolerance by analysis of C-peptide secretion rate after glucose or glucagon injection. The rate was calculated from kinetic analysis of peripheral C-peptide behavior. The rate reached the peak two minutes after glucose injection and then rapidly declined (first-phase secretion) in control subjects. In nonobese subjects with impaired glucose tolerance (IGT) or non-insulin-dependent diabetes mellitus (NIDDM), the rate promptly increased in response to glucose and was followed by a second phase increase. The time course of the rate in the subjects was slightly different from that in control subjects. There was a progressively greater deficit in the first-phase increase with increasing severity of glucose intolerance. The time course of the rate in the obese subjects with NIDDM was different from that in control subjects. The first-phase increase was reduced in the obese subjects with NIDDM. The glucose disappearance rate was correlated with the first-phase increase. Since the time course of the rate after glucagon injection in all subjects did correspond well with that in the control subjects, variation of metabolic clearance rate of endogenous C-peptide among the subjects may be negligible for this study. This study provides the precise time course of first- and second-phase insulin response to glucose injection in nonobese and obese subjects with IGT or NIDDM as well as convincing evidence of the progressive reduction of first-phase insulin response with increasing severity of glucose intolerance. First-phase insulin response to glucose might be slightly delayed in some obese subjects with NIDDM.

Effect of AA-861, a selective 5-lipoxygenase inhibitor, on models of allergy in several species

The effects of 2,3,5-trimethyl-6-(12-hydroxy-5,10-dodecadiynyl)-1,4-benzoquinone (AA-861), a selective 5-lipoxygenase inhibitor, on immunological or non-immunological release of slow reacting substance of anaphylaxis (SRS-A) and histamine and its effects on experimental asthma were investigated. AA-861 showed a dose-dependent inhibition of SRS-A release, with no effect on histamine release from passively sensitized guinea pig, monkey (M. irus) and human lung fragments. An analysis of the anaphylactic diffusate from the human lung fragments, using the combined technique of high performance liquid chromatography and radioimmunoassay, revealed that AA-861 markedly suppresses biosynthesis of the leukotrienes. However, this drug inhibits the release of histamine as well as SRS-A from lung fragments of anaphylactic monkey (M. mulatta) and in the Ca ionophore-stimulated rat peritoneal cavity. AA-861 suppressed the anaphylactically-induced airway resistance in mepyramine- and cimetidine-treated guinea pigs. These results suggest that AA-861 may be clinically effective for treating allergy-related asthma by modulating the 5-lipoxygenase pathway and that an inhibitory mechanism of histamine release by AA-861 may be present in some species.

Lack of involvement of leukotriene and platelet activating factor in passive cutaneous anaphylaxis in rats

Possible chemical mediators contributing to 48 hour passive cutaneous anaphylaxis (PCA) in rats were investigated. Forty-eight hour PCA was inhibited considerably by mepyramine and methysergide given intravenously, a finding suggestive of a major role for histamine and serotonin in the reaction. AA-861, a selective 5-lipoxygenase inhibitor did not inhibit the PCA, and leukotriene (LT)D4 or LTE4 and the combination with prostaglandin (PG)E2 had no significant skin reaction. In addition, only small amounts of slow reacting substance of anaphylaxis (SRS-A) were detected in skin fragments, in vitro. Although CV-3988, a selective platelet activating factor (PAF) antagonist, dose-dependently inhibited the PAF-induced skin reaction, the PCA was not affected by treatment with this compound. Indomethacin also had no inhibitory activity on PCA. Thus, sulfidopeptide LTs, PAF and arachidonate cyclooxygenase metabolites probably do not contribute to PCA, at least in rats.

Analysis of photo-initiators in visible-light-cured dental composite resins

Seven commercial visible-light-cured (VL) dental composite resins were analytically studied for identification of the photo-initiator consisting of photo-sensitizer and reducing agent. Gas-liquid chromatography (GC) was used for the determination of the dilute components extracted from the composite resin. Mass spectroscopy (GC-MS) was used for confirmation of the qualitative data obtained by GC. The results showed that all composite resins examined included camphorquinone (CQ) as a photo-sensitizer. The concentration of CQ in the resin phase, however, ranged from 0.17 to 1.03% w/w. The composite resin with hybrid-sized filler tended to have a higher concentration of CQ than did the micro-filled composite resin. As for the reducing agent, two out of seven brands contained dimethylaminoethyl methacrylate (DMAEMA), and one included dimethyl-p-toluidine (DMPTI). The mixing ratio between CQ and the amine in these three composite resins also varied. Another four brands did not contain either DMAEMA or DMPTI, and would utilize different reducing agents.

Nucleotide and deduced amino acid sequences of two distinct cDNAs for rat phosphoribosylpyrophosphate synthetase

The rat Yoshida sarcoma (YS) cDNA library was screened using oligonucleotide probes designed from peptide sequences of rat phosphoribosylpyrophosphate synthetase, and two distinct clones were obtained. Nucleotide sequencing revealed that both clones encode 317 amino acids containing the peptide sequences. The deduced amino acid sequences of the two differ only by 13 residues (96%) identity), whereas the nucleotide sequences are relatively divergent (81% identity in the coding regions). These results, together with N-terminal amino acid sequencing data, suggest the existence of two different subunits of this enzyme, designated as PRS I and II (their genes as PRPS1 and PRPS2). Transcripts of 2.3 and 3.7 kilobases were detected in YS cells and rat liver by Northern blot analysis, using PRS I and II cDNAs respectively, as probes. In the liver, the expression of both genes increased after partial hepatectomy.

cDNA sequence of human transforming gene hst and identification of the coding sequence required for transforming activity

The hst gene was originally identified as a transforming gene in DNAs from human stomach cancers and from a noncancerous portion of stomach mucosa by DNA-mediated transfection assay using NIH3T3 cells. cDNA clones of hst were isolated from the cDNA library constructed from poly(A)+ RNA of a secondary transformant induced by the DNA from a stomach cancer. The sequence analysis of the hst cDNA revealed the presence of two open reading frames. When this cDNA was inserted into an expression vector containing the simian virus 40 promoter, it efficiently induced the transformation of NIH3T3 cells upon transfection. It was found that one of the reading frames, which coded for 206 amino acids, was responsible for the transforming activity.

Replacement of lysine residue 1030 in the putative ATP-binding region of the insulin receptor abolishes insulin- and antibody-stimulated glucose uptake and receptor kinase activity

To test whether the tyrosine kinase activity of the insulin receptor is crucial for insulin action, we have constructed mutations of the human insulin receptor at Lys-1030, which is in the presumed ATP-binding region. By using oligonucleotide-directed mutagenesis, this lysine residue was replaced with either methionine, arginine, or alanine. Chinese hamster ovary cells were transfected by mutant cDNAs and the expressed insulin receptors were characterized. We show here that none of these mutants exhibited insulin-activated autophosphorylation and kinase activity in vitro. They also do not mediate insulin- and antibody-stimulated uptake of 2-deoxyglucose. The tyrosine kinase activity is thus required for a key physiological response of insulin.

Transforming gene from human stomach cancers and a noncancerous portion of stomach mucosa

DNAs from 21 human stomach cancers, 16 metastatic stomach cancers to lymph nodes, and 21 apparently noncancerous specimens of stomach mucosae from a total of 26 patients with stomach cancer were tested for their ability to induce neoplastic transformation of NIH 3T3 cells on transfection by the calcium phosphate precipitation technique. Three samples of DNA were shown to have transforming activity; one was from a primary stomach cancer of one patient, the second was from a noncancerous portion of stomach mucosa of the same patient, and the third was from a lymph node metastasis of stomach cancer from another patient. These transformants were tumorigenic in nude mice, and DNAs from the cells could induce secondary transformants. A portion of the transforming gene from the stomach cancer of one patient, which contained the sequences expressed in the NIH 3T3 transformants, was cloned. The transforming gene did not have any homology with the transforming sequences reported previously. We have applied the term hst to this novel human transforming gene. The transforming gene, hst, was found to be present in all the primary and secondary transformants induced by the other two samples of DNA.

Amplifications of both c-Ki-ras with a point mutation and c-myc in a primary pancreatic cancer and its metastatic tumors in lymph nodes

Activated c-Ki-ras with a point mutation (GGT to CGT) at codon 12, resulting in the substitution of arginine for glycine, was found in DNA from metastatic pancreatic adenocarcinoma in a lymph node. By means of restriction endonuclease length polymorphism with SacI digestion, we were able to demonstrate that the same point mutation of c-Ki-ras was present in the primary tumor and in metastases in lymph nodes. DNA from the normal spleen of the patient did not have this type of point mutation. Moreover, amplifications of 3- to 6-fold of the activated c-Ki-ras and 50-fold of c-myc were found in the primary tumor and the metastases in the two lymph nodes, indicating that point mutation had occurred at a relatively early stage of the tumor development, before amplification of the gene. This is the first clear demonstration of amplification of activated c-Ki-ras accompanied by amplification of c-myc in both primary and metastatic human tumors in vivo.

[Long-term toxicological studies with mizoribine (Bredinin) in beagle dogs (the first report). Blood chemistries, pharmacokinetics of mizoribine and fertility studies of the male dogs]

For long-term toxicological studies, mizoribine at the dose of 2.5 mg/kg body weight was administered orally to two male and two female Beagle dogs for 36 consecutive months, once a day, 6 days a week, with a day-off on the 7th of each week. As a control group, 2 male and 2 female dogs were kept under the same conditions as the treated group. The above experiment resulted in no abnormal general symptoms being found in either group. In addition, body weight gain instead of weight loss was observed in both groups. Moreover, hematological and biological parameters were in the normal range, and no statistical difference was obtained between the two groups. An additional 10 mg/kg of mizoribine was administered once to both groups at the months of 6, 12, 18, 24, or 36 after the onset of this toxicological study so as to determine the pharmacokinetic behavior of serum mizoribine. This resulted in no significant difference being observed between the two groups. Therefore, it can be inferred that accumulation of mizoribine is not induced by its long-term repeated administration. In fertility study, the analysis of the sperm and the mating ability of a male dog with an appropriate healthy female dog revealed that mizoribine at this dose did not provoke any abnormalities in male gonadal functions.