Evidence that two zinc fingers in the methionine aminopeptidase from Saccharomyces cerevisiae are important for normal growth

Limited proteolysis of intact yeast methionine aminopeptidase (MAP1) with trypsin releases a 34 kDa fragment whose NH2-terminal sequence begins at Asp70, immediately following Lys69. These results suggest that yeast MAP may have a two-domain structure consisting of an NH2-terminal zinc finger domain and a C-terminal catalytic domain. To test this, a mutant MAP lacking residues 2-69 was generated, overexpressed, purified and analyzed. Metal ion analyses indicate that 1 mol of wild-type yeast MAP contains 2 mol of zinc ions and at least 1 mol of cobalt ion, whereas 1 mol of the truncated MAP lacking the putative zinc fingers contains only a trace amount of zinc ions but still contains one mole of cobalt ion. These results suggest that the two zinc ions observed in the native yeast MAP are located at the Cys/His rich region and the cobalt ion is located in the catalytic domain. The kcat and Km values of the purified truncated MAP are similar to those of the wild-type MAP when measured with peptide substrates in vitro and it appears to be as active as the wild-type MAP in vivo. However, the truncated MAP is significantly less effective in rescuing the slow growth phenotype of map mutant than the wild-type MAP. These findings suggest that the zinc fingers are essential for normal MAP function in vivo, even though the in vitro enzyme assays indicate that they are not involved in catalysis.(ABSTRACT TRUNCATED AT 250 WORDS)

CT analysis of postoperative changes after thalamotomy for Parkinson's disease

Stereotactic operations have long been used to relieve agitation and muscle rigidity in Parkinson disease. Because of its high-density resolution, CT is quite effective to portray the location, size, shape and density of the thermocoagulative focus. The foci were classified into different types according to their changes in different time periods. Correlation with pathological changes was discussed.

[A prospective study on the relationship between body mass index and mortality from all causes in 15,827 middle aged and elderly citizens]

The association between Body Mass Index (BMI) and mortality from all causes was investigated in a cohort study of 15827 citizens (aged 35 and over) in Shanghai. During about 3-year follow up the person-year mortality for men and women were 1311.78/100000 and 1036.87/100000, respectively. Cox regression analysis was conducted in a lower and an upper range of BMI, respectively. The inverse association between BMI and mortality in the lower range was statistically significant for men and women. The positive association between BMI and mortality in the upper range was highly statistically significant for women but not for men. Logistic regression analysis conducted over the entire range of BMI showed that BMI and all-cause mortality association was significantly "L"-shaped distribution for men and women. The mortality or relative hazard curve can be fit with quadratic model (Y = a-bX + cX2) in different sex.

A tyrosyl-tRNA synthetase can function similarly to an RNA structure in the Tetrahymena ribozyme

Group I introns are highly structured RNAs which catalyse their own splicing by guanosine-initiated transesterification reactions. Their catalytic core is generally stabilized by RNA-RNA interactions within the core and with peripheral RNA structures. Additionally, some group I introns require proteins for efficient splicing in vivo. The Neurospora CYT-18 protein, the mitochondrial tyrosyl-transfer RNA synthetase (mt TyrRS), promotes splicing of the Neurospora mitochondrial large ribosomal RNA (LSU) and other group I introns by stabilizing the catalytically active structure of the intron core. We report here that CYT-18 functions similarly to a peripheral RNA structure, P5abc, that stabilizes the catalytic core of the Tetrahymena LSU intron. The CYT-18 protein and P5abc RNA bind to overlapping sites in the intron core, inducing similar conformational changes correlated with splicing activity. Our results show that a protein can play the role of an RNA structure in a catalytic RNA, a substitution postulated for the evolution of nuclear pre-messenger RNA introns from self-splicing introns.

Disruptions in Golgi structure and membrane traffic in a conditional lethal mammalian cell mutant are corrected by epsilon-COP

The CHO cell temperature-sensitive mutant ldlF exhibits two defects in membrane traffic at the nonpermissive temperature (39.5 degrees C): rapid degradation of LDL receptors, possibly caused by endocytic missorting, and disruption of ER-through-Golgi transport. Here, we show that at 39.5 degrees C, the Golgi in ldlF cells dissociated into vesicles and tubules. This dissociation was inhibited by AlF4-, suggesting trimeric G proteins are involved in the dissociation mechanism. This resembled the effects of brefeldin A on wild-type cells. We isolated a hamster cDNA that specifically corrected the ts defects of ldlF cells, but not those of other similar ts mutants (ldlE, ldlG, ldlH, and End4). Its predicted protein sequence is conserved in humans, rice, Arabidopsis, and Caenorhabditis elegans, and is virtually identical to that of bovine epsilon-COP, a component of the coatomer complex implicated in membrane transport. This provides the first genetic evidence that coatomers in animal cells can play a role both in maintaining Golgi structure and in mediating ER-through-Golgi transport, and can influence normal endocytic recycling of LDL receptors. Thus, along with biochemical and yeast genetics methods, mammalian somatic cell mutants can provide powerful tools for the elucidation of the mechanisms underlying intracellular membrane traffic.

Segmental transarterial chemoembolization with Lipiodol mixed with anticancer drugs for nonresectable hepatocellular carcinoma: follow-up CT and therapeutic results

We developed segmental Lp-TAE, which is transcatheter hepatic sub-subsegmental, subsegmental, or segmental chemoembolization using Lipiodol introduced into the tumor-bearing hepatic sub-subsegment, subsegment, or segment as the target area. A total of 98 patients with nonresectable hepatocellular carcinoma (HCC) undergoing segmental Lp-TAE (Seg-Lp-TAE) were studied, and the relationship between the CT pattern observed after Seg-Lp-TAE (Seg-Lp-CT) and the therapeutic results obtained in those patients was evaluated. Seg-Lp-CT was classified into four types (type I, homogeneous; type II, defective; type III, inhomogeneous; and type IV, only slight accumulation, if any) according to the Lipiodol accumulation pattern observed after Seg-Lp-TAE. The cumulative nonrecurrence rates of type I were higher than those of types II-IV. The cumulative survival rates of type Ia, in which Lp accumulation is also seen around the main tumor, were the highest (93.8% at 1 year, 85.9% at 2 years, 85.9% at 3 years, and 57.3% at 4 years). The cumulative survival rates achieved with Seg-Lp-TAE were 89.2% at 1 year, 69.4% at 2 years, 58.9% at 3 years, 44.0% at 4 years, and 30.2% at 5 years, which were higher than those achieved with conventional Lp-TAE. Seg-Lp-TAE is very useful in the treatment of HCC limited to one sub-subsegment, subsegment, or segment, and it is important to choose sub-subsegmental, subsegmental, or segmental Lp-TAE on the basis of the size and site of the tumor as well as the type and the number of feeding arteries.

Effect of moderate hypothermia on lipid peroxidation in canine brain tissue after cardiac arrest and resuscitation

BACKGROUND AND PURPOSE

We sought to examine the effect of moderate hypothermia (30 degrees C to 32 degrees C) initiated after resuscitation on the scavenging systems of free radicals and lipid peroxidation in canine brain tissue after cardiac arrest and resuscitation.

METHODS

Twenty-one dogs were divided into four groups: group A, nonischemic controls (shams) (n = 4); group B, 15-minute cardiac arrest without reperfusion (n = 4); group C, 15-minute cardiac arrest and standard resuscitation (n = 6); and group D, 15-minute cardiac arrest and hypothermic resuscitation (n = 7). During the period of 10 to 120 minutes after resuscitation, brain temperature and core temperature in group D remained at 30 degrees C to 32 degrees C and were 4 degrees C to 5 degrees C lower than in group C. For each dog, a sample of right parietal cerebral cortex was obtained from group A, group B, or from group C and group D at 2 hours after resuscitation. The sample was assayed for tissue malondialdehyde (MDA), the content of reduced glutathione (GSH), and the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX).

RESULTS

In group B, a 15-minute cardiac arrest induced an increase in MDA, a significant reduction of GSH, and no change in SOD and GSH-PX activities compared with group A. In group C, there were further increases in MDA and reductions in GSH content and GSH-PX activity compared with group A; SOD activity remained substantially unchanged. The content of MDA was higher in group D than in group A but less elevated in group D than in group C. The GSH content and SOD and GSH-PX activities were significantly higher in group D than in group C.

CONCLUSIONS

Moderate hypothermia initiated after resuscitation can significantly inhibit the accumulation of lipid peroxidation products and the consumption of free radical scavengers in the brain tissue.

Percutaneous hot saline injection therapy for hepatic tumors: an alternative to percutaneous ethanol injection therapy

PURPOSE

To evaluate the usefulness of percutaneous hot saline injection therapy (PSIT) in the treatment of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty patients with HCC (23 nodules) underwent PSIT. Mean tumor diameter was < or = 30 mm. PSIT was performed by injecting hot saline into the HCC. The therapeutic effect of PSIT was evaluated with computed tomography, angiography, measurement of alpha-fetoprotein levels, and histopathologic examination of needle biopsy and resected specimens.

RESULTS

No complications were encountered, and a therapeutic effect was obtained in all cases. When the injected material cools, it becomes physiologic saline making it possible to inject relatively large volumes in a single session.

CONCLUSION

PSIT has promise as a form of curative local therapy for small HCCs and is expected to exert a safe and favorable therapeutic effect on large HCCs as well.

Monitoring of pO2 by spin-spin relaxation rate 1/T2 of 19F in a rabbit abscess model

The purpose of this study was to confirm the relationship of T1 and T2 relaxation rate vs. pO2 in vivo of 19F MR signal measured from intracellular perflubron. Our work to date has demonstrated that 1/T2 is more sensitive to pO2 than 1/T1 in the in vitro environment. The advantage of 1/T2 vs. 1/T1 is the speed of measurement and sensitivity. Seven alternating T1 and T2 measurements were obtained during a continuous acquisition using the TTISS pulse sequence. An abscess model was used for the in vivo experiments where rabbits were infused with 5ml/kg Oxygent HT 10 days prior to scanning. The abscess model was used because it has been shown that perflubron accumulates in macrophages located in the abscess wall. This technique thus provided signal from the intracellular milieu. The results of this study proved that pO2 monitoring by measuring T2 of 19F is feasible and can be used in-lieu of the T1 measurement. Given that the T2 measurement is much more rapid than the T1 measurement and that T2 changes are more sensitive than T1 changes with alterations in pO2, T2 should prove to be practical and useful for monitoring transient rapid changes in pO2.

Effect of qingyangshen on hippocampal alpha- and beta-tubulin gene expression during kainic acid induced epileptogenesis

Using alpha- and beta- tubulin cDNA Probes and Northern blot hybridization technique, we analyzed the effect of intraperitoneally injected Qingyangshen (QYS), a traditional Chinese medicine with antiepileptic property, and diphenylhydrantoin sodium (DPH) on hippocampal alpha- and beta-tubulin gene expression during kainic acid (KA) induced chronic seizures. It was found that: 1) thirty days after intraperitoneal injection of KA, alpha- and beta-tubulin mRNAs in animals showing chronic seizures increased 3.02 +/- 1.05 and 4.07 +/- 1.32 times respectively compared with control; 2) neither QYS (15 mg/kg, q.o.d. x 6) nor DPH (50 mg/kg, q.o.d. x 6), when used separately, could inhibit the above mentioned effect of KA; 3) when QYS (15 mg/kg, q.o.d. x 6) and DPH (50 mg/kg, q.o.d. x 6) were given in combination, the long-term increase in tubulin gene expression induced by KA was significantly reduced, with alpha- and beta-tubulin mRNAs being decreased to 0.44 +/- 0.08 and 0.50 x 0.10 times of corresponding values in animals treated with KA alone. The results indicate that the mechanism of antiepileptic effect of QYS is at least partially related to the inhibition of tubulin synthesis and subsequent reduction in mossy fiber sprouting and neosynaptogenesis.

Ets oncogene-related gene Elg functions in Drosophila oogenesis

Members of the ets gene family encode transcription factors that regulate the expression of a variety of cellular and viral genes including several protooncogenes. We have utilized Drosophila to elucidate the in vivo function of one family member. We show by complementation rescue and sequence analysis that the female sterile mutant tiny eggs (tne) is an allele of the Drosophila Ets-related gene Elg (also called D-elg). The mutation of a highly conserved tyrosine residue in the ETS DNA-binding domain of the Elg gene product demonstrates that normal gene function is required for proper follicle cell migration, chorion formation, and nurse cell-chromosome decondensation during Drosophila oogenesis.

Electron Localization in Metallic Quasicrystals

Bulk icosahedral-quasicrystalline aluminum-palladium-rhenium alloys of high structural quality and thermal stability are found to exhibit low-temperature electrical resistivities that are four orders of magnitude larger than those found in disordered metals and metallic glasses. Experiments suggest that these quasiperiodic alloys, which have a semimetallic electron density, are insulators at low temperature. The findings are discussed in light of theories on electron localization and band-gap formation in ordered metallic systems.

[Percutaneous hot water injection therapy (PHoT) for hepatic tumors: a clinical study]

Percutaneous ethanol injection therapy (PEIT) has become widely used in the treatment of HCC. However, the indications for this method are limited by the toxicity of ethanol itself. Against this background, the authors turned their attention to the heat coagulation necrosis effect induced by boiled physiological saline (hot water) and devised percutaneous hot water injection therapy (PHoT) as a new local treatment method. PHoT was performed a total of 41 times in 13 patients (16 nodules) with HCCs measuring < or = 3 cm. Changes in AFP values, CT findings, angiographic findings before and after treatment, and histopathological findings of needle biopsy or resected specimen were investigated. AFP values decreased in all of the seven patients who initially showed high values. On CT, all lesions receiving PHoT became hypodense, with this change thought to indicate necrosis. Disappearance of the tumor stain was confirmed in the four patients in whom follow-up angiography was performed. In the six patients in whom needle biopsy was performed, disappearance and scaring of tumor cells were observed, while in the one patient in whom the tumor was resected, complete necrosis of the tumor was confirmed. PHoT, despite a small number of punctures, shows good anti-tumor effects, and has promise not only as a curative local treatment method for small HCCs but also in combination with TAE for large HCCs.

Structure of a parallel-stranded tetramer of the Oxytricha telomeric DNA sequence dT4G4

We report here the determination of the solution structure of the single-copy tetramer of the sequence dT4G4, the unit repeat in telomeres of the ciliated protozoan Oxytricha, in the presence of potassium ions. This is accomplished by a combination of sequential assignments and distance determinations from 2D proton NMR with model building, based on conformational analysis of the structure using a full-matrix NOESY simulation and molecular dynamics. Each strand in this tetramer structure has an identical environment and conformation: a parallel-stranded, right-handed helix, with all nucleotides in the C2'-endo, anti configuration. The T flanking the G cluster stacks in a 4-fold symmetrical helical array, while the remaining T's become increasingly flexible and sample multiple stacked configurations.

Segmental transcatheter hepatic artery chemoembolization with iodized oil for hepatocellular carcinoma: antitumor effect and influence on normal tissue

PURPOSE

Segmental transcatheter arterial embolization (TAE) with use of iodized oil mixed with an anticancer drug, followed by injection of gelatin sponge particles, was undertaken to evaluate its antitumor effect and its influence on normal tissue in patients with hepatocellular carcinoma (HCC).

PATIENTS AND METHODS

Histologic findings in 12 patients who underwent hepatectomy after segmental TAE were compared with findings on plain radiographs and computed tomographic (CT) scans. Visualization of the portal veins contiguous to the tumor on radiographs and the pattern of iodized oil accumulation in the tumor and vicinity on CT scans after TAE were assessed.

RESULTS

Complete necrosis of the tumor was achieved in 10 cases (83%), while complete necrosis of daughter nodules and capsular invasion was observed histologically in eight of these 10 patients (80%). The degree of tumor necrosis correlated with the pattern of iodized oil accumulation in and near the tumor. Partial necrosis of normal tissue near the tumor correlated with accumulation of iodized oil.

CONCLUSION

Segmental TAE may be an excellent therapeutic method for treatment of HCC that is localized in one or a few segmental or subsegmental regions.

[CO2US via an implantable port--drug distribution in intraarterial chemotherapy for hepatic tumors and evaluation of effect]

The distribution of blood flow was determined from the distribution of CO2 by US performed during the infusion of CO2 microbubbles via an implantable port (IP-CO2US) in intraarterial chemotherapy for hepatic tumor, and the usefulness of this method in determining tumor vascularity and evaluating the effects of therapy was investigated. A total of 16 patients, 12 of whom had metastatic liver tumor, two hepatocellular carcinoma, one gall bladder carcinoma, and one cholangiocellular carcinoma were studied. The enhanced areas in the liver in 16 patients in whom IP-CO2US was performed a total of 24 times were consistent in all cases with the enhanced areas demonstrated by IP-RI angiography performed a total of 10 times within 10 days, and were also consistent with one exception with the enhanced areas demonstrated by IP-CTA performed 14 times. The tumor detection rate was markedly higher with IP-CO2US than with plain US or IP-DSA, and was similar to that of IP-CTA. Evaluation of the vascularity of individual nodules by IP-CO2US surpassed that by IP-DSA, and was similar to that of IP-CTA. It was demonstrated that blood flow distribution (intrahepatic drug distribution) can be equally well grasped with IP-CO2US, which is a simple and convenient method, as with IP-RI angiography. It was also suggested that IP-CO2US is useful in the evaluation of tumor vascularity and the effect of therapy.

Effect of thymine tract length on the structure and stability of model telomeric sequences

DNA from the telomeres at the ends of eukaryotic chromosomes contains a stretch of simple tandemly repeated sequences in which clusters of G residues alternate with clusters of T/A sequences along one DNA strand. Model telomeric G-clusters form four-stranded structures in Na+ or K+, stabilized by Hoogsteen pairing between G bases. DNA containing a single copy of the G-cluster can self-associate to form tetramers, with a parallel-stranded, right-handed helical structure. Two copies of the 3'-terminal G strand form a folded-back hairpin that dimerizes to create an antiparallel quadruplex structure. We show here that the tetrameric structure is strongly influenced by the T residue flanking either side of the G-cluster. The parallel tetraplex formed by single copies of the sequences dTnG4 is most stable for n = 1 and least stable for n = 8, the longest tract we have studied. At least two thymine residues are required to allow formation of antiparallel folded-back hairpin dimers from two-copy oligomers of sequence d(TnG4)2 in Na+; additional T's destabilize this structure. In K+, the predominant structure formed is the four-stranded parallel tetramer in all cases. Kinetic analysis indicates that the quadruplex structure formed by Oxytricha telomeric DNA overhangs in the presence of Na+ arises by dimerization of two Hoogsteen base-paired hairpins, with a relatively low energy barrier.

[Study on the evaluation of recurrence of HCC and the effect after transcatheter hepatic arterial embolization--fluctuations in AFP values]

To determine the usefulness of alpha-fetoprotein (AFP) in determining recurrence of HCC after interventional angiography (IVA) and to define the relation between AFP and the imaging diagnosis of HCC recurrence, changes in AFP values in 160 patients with hepatocellular carcinoma who were treated by IVA > or = two times were classified into four patterns: A: the AFP value was decreased after the first IVA, increased at recurrence and decreased again after the second IVA; B: the AFP value was unchanged after the first IVA, but increased at recurrence and decreased after the second IVA; C: the AFP value was decreased after the first IVA, but was not increased at recurrence; D: the AFP value showed no change. The frequency of each AFP pattern and the diagnosis of recurrence by AFP were determined. The relation between tumor type and AFP was defined. Pattern A was the most frequently detected. In 62.6%, AFP was increased at recurrence (A and B), and there was a positive correlation between changes in the AFP value and the findings of imaging diagnosis. In another 37.5%, AFP was not increased at recurrence (C and D), and therefore, the diagnosis of HCC recurrence by imaging methods was very important.

Electrophysiological and pathological observations on experimental coxsackie B-3 viral myocarditis in mice

Electrophysiological action of right ventricular myocardium examined by standard intracellular microelectrode technique and real-time microcomputer data processor system and histological and ultrastructural changes of myocardium in BALB/c mice infected with coxsackie B-3 virus from 3 days to 9 months were observed. It was found that electrophysiologic parameters of action potential changed very quickly at the early stage (3 days to 1 month) of the disease. Those abnormalities became most apparent by the 5-30th day, and 7 patterns of abnormal action potential occurred frequently within the same period. These changes were basically parallel to the myocardial lesions. At the late stage (3-9 months) the electrophysiological parameters were nearly normal, while the myocardial lesions decreased gradually. However, the abnormal patterns of action potential were still detected, even though they were improved gradually. The results suggest that myocardial damages caused by viral infection may lead to changes of cardiac electric action, which may be one of the factors in arrhythmias in the episode of viral myocarditis.

Thermodynamics of G-tetraplex formation by telomeric DNAs

Telomeres are structures at the ends of eukaryotic chromosomes, the DNA of which contains stretches of tandemly repeated sequences with G clusters along one strand. Model telomeric G-rich DNAs can form different tetraplex structures, stabilized by cyclic hydrogen bonding of four guanines in the presence of metal ions such as Na+ or K+. Oligonucleotides with a single copy of the Oxytricha sequence dT4G4 form a tetramer, with a parallel-stranded, right-handed helical structure. Additional copies favor folded-back structures that associate to form an antiparallel dimer. The parallel-stranded tetramer has all G's in the anti configuration, while the folded-back dimer has alternating syn and anti nucleotide conformations along each strand. Here we have constructed two G-tetraplex structures, containing identical G-tetrad base pairs, from oligonucleotides. One has the truncated telomeric sequence from Oxytricha, dG4T4G4, which forms an antiparallel G-quartet structure; the second is constrained to form a parallel G-strand arrangement by insertion of a 5'-p-5' linkage between two dT2G4 sequences. Each oligomer forms a defined G-tetraplex dimeric structure in the presence of Na+. The standard-state enthalpies, entropies, and free energy for formation of these tetraplexes have been determined. The parallel strand structure is thermodynamically more stable than the antiparallel one, primarily because of both greater enthalpy and entropy of formation. In addition, the two molecules differ in their interaction with sodium ions, reflecting a difference in ion binding and therefore in structure between the two forms.