[Preoperative embolization of paraganglioma in head and neck]

Preoperative embolization of 10 cases of paraganglioma in carotid artery body and jugular foramen region via endovascular approach was performed. Tumor vessels were obliterated 100% in 7 cases and 80% - 90% in 3 cases as was demonstrated by angiography. It is available for us to reduce bleeding, expose tumor, avoid the iatrogenic damage of the important vessels and nerves around tumor during operation and to total resection possible. Additionally, the manipulating points of embolization are discussed.

Repression of the Klebsiella aerogenes nac promoter

Transcription of the nitrogen-regulated nac promoter of Klebsiella aerogenes requires sigma54 RNA polymerase, is activated by the phosphorylated form of the transcription factor nitrogen regulator I (NRI) (NtrC), and is repressed by the product of the nac gene, Nac. Nac protects a large portion of the nac control region, extending from positions -130 to -70, from digestion by DNase I. This site(s) lies immediately upstream from the site at which sigma 54 RNA polymerase binds, is downstream of a high-affinity binding site for the transcriptional activator NRI approximately P, and partially overlaps a low-affinity NRI approximately P-binding site. Binding of Nac to the DNA resulted in bending of the DNA but did not interfere with the binding of sigma 54 RNA polymerase to the promoter or with the binding of NRI approximately P to either the high-affinity site or low-affinity site. Furthermore, transcription assays with various wild-type and mutant templates suggested that Nac did not exclude NRI approximately P from either the low- or high-affinity sites, nor did Nac interfere with the ability of the polymerase to form the open complex when the binding sites for NRI approximately P were moved to different locations upstream from the promoter. Rather, Nac seemed to repress by an antiactivation mechanism in which the interaction of the NRI approximately P, bound at its normal sites, with sigma 54 RNA polymerase, bound to the promoter, was prevented.

Activation of transcription initiation from the nac promoter of Klebsiella aerogenes

The nac gene of Klebsiella aerogenes encodes a bifunctional transcription factor that activates or represses the expression of several operons under conditions of nitrogen limitation. In experiments with purified components, transcription from the nac promoter was initiated by sigma 54 RNA polymerase and was activated by the phosphorylated form of nitrogen regulator I (NRI) (NtrC). The activation of the nac promoter required a higher concentration of NRI approximately P than did the activation of the Escherichia coli glnAp2 promoter, and both the promoter and upstream enhancer element contributed to this difference. The nac promoter had a lower affinity for sigma 54 RNA polymerase than did glnAp2, and uninitiated competitor-resistant transcription complexes formed at the nac promoter decayed to competitor-sensitive complexes at a greater rate than did similar complexes formed at the glnAp2 promoter. The nac enhancer, consisting of a single high-affinity NRI-binding site and an adjacent site with low affinity for NRI, was less efficient in stimulating transcription than was the glnA enhancer, which consists of two adjacent high-affinity NRI-binding sites. When these binding sites were exchanged, transcription from the nac promoter was increased and transcription from the glnAp2 promoter was decreased at low concentrations of NRI approximately P. Another indication of the difference in the efficiency of these enhancers is that although activation of a nac promoter construct containing the glnA enhancer was relatively insensitive to subtle alterations in the position of these sites relative to the position of the promoter, activation of the natural nac promoter or a nac promoter construct containing only a single high-affinity NRI approximately P binding site was strongly affected by subtle alterations in the position of the NRI approximately P binding site(s), indicating a face-of-the-helix dependency for activation.

Effect of antihydatid drugs on carbohydrate metabolism of metacestode of echinococcus granulosus

A biochemical some enzymes of glycolysis and a partial reversed tricarboxylic acid cycle together with hydrolytic enzymes in the cyst wall of Echinococcus granulosus was carried out. Lactate dehydrogenase (LDH), pyruvate kinase (PK), phosphoenolpyruvate carboxykinase (PEPCK), and adenosine triphosphatase (ATPase) showed their high level of activity, suggesting that the proliferation of E. granulosus cyst wall is an energy-dependent process and the major pathways for glucose metabolism is glycolysis. Treatment of E. granulosus-infected mice with mebendazole and albendazole resulted in marked inhibition of PK, PEPCK and ATPase of E. granulosus cyst wall, whereas praziquantel had no effect, indicating that PK, PEPCK, and ATPase might be chemotherapeutic targets and the differences in the inhibitory effects might account for the efficacy of the three antihydatid drugs.

The RNA component of human telomerase

Eukaryotic chromosomes are capped with repetitive telomere sequences that protect the ends from damage and rearrangements. Telomere repeats are synthesized by telomerase, a ribonucleic acid (RNA)-protein complex. Here, the cloning of the RNA component of human telomerase, termed hTR, is described. The template region of hTR encompasses 11 nucleotides (5'-CUAACCCUAAC) complementary to the human telomere sequence (TTAGGG)n. Germline tissues and tumor cell lines expressed more hTR than normal somatic cells and tissues, which have no detectable telomerase activity. Human cell lines that expressed hTR mutated in the template region generated the predicted mutant telomerase activity. HeLa cells transfected with an antisense hTR lost telomeric DNA and began to die after 23 to 26 doublings. Thus, human telomerase is a critical enzyme for the long-term proliferation of immortal tumor cells.

Cataloging altered gene expression in young and senescent cells using enhanced differential display

Recently, a novel PCR-based technique, differential display (DD), has facilitated the study of differentially expressed genes at the mRNA level. We report here an improved version of DD, which we call Enhanced Differential Display (EDD). We have modified the technique to enhance reproducibility and to facilitate sequencing and cloning. Using EDD, we have generated and verified a catalog of genes that are differentially expressed between young and senescent human diploid fibroblasts (HDF). From 168 genetags that were identified initially, 84 could be sequenced directly from PCR amplified bands. These sequences represent 27 known genes and 37 novel genes. By Northern blot analysis we have confirmed the differential expression of a total of 23 genes (12 known, 11 novel), while 19 (seven known, 12 novel) did not show differential expression. Several of the known genes were previously observed by others to be differentially expressed between young and senescent fibroblasts, thereby validating the technique.

Comparative mechanisms of 4-aminopyridine-resistant Ito in human and rabbit atrial myocytes

The cardiac transient outward current (Ito) has been shown in several species to consist of two components: 1) a 4-aminopyridine (4-AP)-sensitive component (Ito1) and 2) a 4-AP-resistant component (Ito2). In rabbits, Ito2 is a Ca(2+)-dependent Cl- current [ICl(Ca)]; similar mechanisms have been suggested to underlie Ito2 in human atrium. We used whole cell patch-clamp techniques to define the mechanism of Ito2 (defined as the component resistant to 5 mM 4-AP) in human atrial myocytes, with parallel experiments performed in rabbit atrial cells. In rabbit atrium, Ito2 activated more slowly than Ito1 and had a bell-shaped current-voltage of Ito with properties similar to Ito2 in the rabbit, and a similar component recorded with pipette K+ replaced by Cs+ was suppressed by the substitution of methanesulfonate for Cl- in the superfusate. In human cells, a 4-AP-resistant Ito2 was recorded at a depolarizing pulse frequency of 1 Hz, but not at 0.1 Hz. Ito2 activated rapidly and inactivated earlier than Ito1, whereas its I-V relation was linear like that of Ito1. Ryanodine had no effect on human atrial Ito. When K(+)-free pipette solutions were used, no Ito was recorded in 30 human atrial myocytes, and external Cl- replacement with methanesulfonate failed to reveal an Ito. In 13 human myocytes, isoproterenol increased ICa but failed to activate an Ito compatible with ICl(Ca). Whereas caffeine suppressed human atrial Ito, it also suppressed Ito1 [in the presence of 200 microM Cd2+ to block ICa and 5 mM intracellular ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid to buffer intracellular Ca2+] in both human and rabbit atrium, indicating an action unrelated to Ca(2+)-triggered Ca2+ release. In conclusion, we were unable to demonstrate the presence of ICl(Ca) in human atrial myocytes, and the 4-AP-resistant component of Ito appeared to be due to 4-AP unblocking.

Idiopathic atrial fibrillation in dogs: electrophysiologic determinants and mechanisms of antiarrhythmic action of flecainide

OBJECTIVES

This study sought to determine the mechanisms of idiopathic atrial fibrillation and the atrial antifibrillatory action of flecainide in dogs.

BACKGROUND

In a small subset of dogs, sustained atrial fibrillation can be readily induced in the absence of vagal tone. The electrophysiologic mechanisms underlying this ability to sustain atrial fibrillation, and of flecainide action on the arrhythmia, are unknown.

METHODS

Six dogs with inducible sustained atrial fibrillation were studied before and after flecainide administration and compared with a control group of 10 dogs.

RESULTS

Dogs with atrial fibrillation differed in displaying more shortening of the atrial refractory period with increased rate, resulting in a significantly shorter refractory period and wavelength for reentry at rapid rates, and in increased regional dispersion in refractoriness. Activation maps during sustained fibrillation showed a mean (+/- SE) of 6.3 +/- 0.4 coexistent zones of reentry, compatible with short wavelengths, whereas in control dogs activation during self-limited atrial fibrillation was better organized, and the number of reentrant circuits was smaller. Quantitative analysis demonstrated significantly greater inhomogeneity of activation during atrial fibrillation in dogs with atrial fibrillation than in control animals. Flecainide terminated atrial fibrillation by increasing the duration and homogeneity of atrial refractoriness at rapid rates, thereby reducing the number of reentry circuits and the heterogeneity of activation.

CONCLUSIONS

The ability of atrial fibrillation to sustain itself resulted from enhanced rate-dependent shortening of atrial refractoriness and increased regional heterogeneity. Flecainide reversed these changes and restored sinus rhythm. These results suggest potential mechanisms of idiopathic atrial fibrillation and are pertinent to understanding the clinical actions of flecainide.

Selective effects of alfentanil on nociceptive-related neurotransmission in neonatal rat spinal cord

We have examined the effects of alfentanil on nociceptive-related neurotransmission in isolated neonatal rat spinal cord, with particular attention to acute tolerance. Electrical stimulation of a lumbar dorsal root was used to evoke the monosynaptic reflex (MSR), a slow ventral root potential (sVRP), and the dorsal root potential (DRP). Alfentanil (0.5 nmol litre-1 to 1 mumol litre-1) depressed sVRP area by a maximum of 85%; EC50 was approximately 2 nmol litre-1. The effects of alfentanil were selective for very slow, metabotropically mediated sVRP components compared with faster NMDA receptor-mediated components. The MSR was unaffected. Alfentanil depressed DRP area by a maximum of 50% at 1 mumol litre-1. Naloxone antagonized all alfentanil effects. Morphine depressed sVRP area with an approximate EC50 of 90 nmol litre-1, giving an alfentanil:morphine potency ratio of 45:1. The effects of alfentanil on sVRP showed no biphasic time dependence up to 60 min. Naloxone administered after alfentanil produced a significant rebound in sVRP area to a level of 143 (SD 21.3)% above control. Thus, in this study there was no evidence for acute tolerance, as measured by a decrease in effectiveness over time, but there was evidence as measured by rebound following naloxone.

Reactivity of monoclonal antibodies established against a recombinant human endogenous retrovirus-K (HERV-K) envelope protein

Human endogenous retroviruses (HERVs) are widely believed to represent possible pathogenic agents in autoimmune disorders and carcinogenesis. We generated 2 monoclonal antibodies (mAbs) against a recombinant HERV-K outer-membrane envelope protein. These mAbs were capable of immunoprecipitating protein bands of 55, 51 and 45 kDa, respectively, from [35S]methionine-labeled lysates of T47D (human breast carcinoma), Raji, Bjab (both human beta-lymphoblastoid) and H9 (human T-cell lymphoma) cells. Furthermore, the 55 kDa band could be precipitated from cell-free supernatant of biosynthetically labeled T47D cells, indicating that this molecule may be secreted. Indirect immunofluorescence and subsequent FACS analysis demonstrated the presence of these molecules on T47D, HeLa, Raji, Bjab and H9 cells as well as on lymphocytes isolated from tonsils and stimulated with poke weed mitogen (PWM). Due to the broad distribution and lack of detection of HERV-K-env mRNA in these cells, we believe that these antigens are of cellular origin detected by crossreactivity of mAbs against HERV-K-env protein with cellular molecules.

Contribution of ATP-sensitive potassium channels to the electrophysiological effects of adenosine in guinea-pig atrial cells

1. Adenosine caused dose-dependent action potential abbreviation in multicellular guinea-pig atrial preparations, an action antagonized by glyburide (IC50, 31 microM) in both physiological and low-chloride superfusate. 2. When 5 mM ATP was included in pipettes for whole-cell voltage clamp of isolated guinea-pig atrial myocytes, adenosine (10 microM) increased the holding current at -40 mV from 41 +/- 8 to 246 +/- 31 pA (mean +/- S.E.M., P < 0.01), and glyburide (20 microM) returned the holding current to 69 +/- 11 pA (P < 0.01 vs. adenosine alone). Acetylcholine (10 microM) also increased the holding current, but its effects were not altered by glyburide. 3. Both adenosine and acetylcholine induced an additional current component in response to 500 ms voltage steps. Glyburide partially inhibited the adenosine-induced current, but did not alter the effect of acetylcholine. In the presence of maximally effective acetylcholine concentrations, adenosine increased membrane conductance (P < 0.01), although to a lesser extent than in the absence of acetylcholine. 4. Single K+ channel activity was seen in only one of eight cell-attached patches in the absence of adenosine or acetylcholine (0.5 mM Ba2+ in bath and pipette solutions). With acetylcholine (10 microM) in the pipette, inwardly rectifying channels (conductance, 41 +/- 5 pS) were seen in five of six patches. With adenosine (10 microM) in the pipette, single-channel activity was seen in twelve of fourteen patches with two populations of channels, one similar to that induced by acetylcholine and another higher-conductance channel (72 +/- 5 pS) that showed less inward rectification. Glyburide (20 microM) suppressed the high-conductance channel (68 +/- 2 pS) leaving a single channel type with a conductance of 36 +/- 5 pS and strong inward rectification. 5. We conclude that K+ATP channels contribute to the electrophysiological actions of adenosine on guinea-pig atrium in the presence of physiological intracellular ATP levels, and may therefore play a role in the cardiac electrophysiological effects of adenosine in the absence of myocardial ischaemia.

Role of chloride currents in repolarizing rabbit atrial myocytes

Rabbit atrial cells manifest a prominent transient outward K+ current (Ito1), but this current recovers slowly from inactivation and is unlikely to be important at physiological rates (3-5 Hz). Depolarization of rabbit atrial cells also elicits a transient Ca(2+)-dependent outward Cl- current (Ito2). To compare the relative magnitude of these transient outward currents at various rates, we applied whole cell voltage-clamp techniques to isolated rabbit atrial myocytes. Whereas peak Ito1 exceeded Ito2 at slow rates (0.1 Hz), Ito1 was strongly reduced as rate was increased (by 97 +/- 2%, mean +/- SE, at 4 Hz), while Ito2 was slightly reduced (by 28 +/- 4%, 4 Hz). The reversal potential of transient outward tail currents at 0.07 Hz was -49 +/- 9 mV, while at 2.5 Hz the reversal potential became -18 +/- 7 mV (calculated Cl- reversal potential -18 mV). The addition of the Cl- transport blocker 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS; 150 microM) or the replacement of external Cl- with methanesulfonate inhibited a large part of the transient outward current elicited by depolarization at 4 Hz. DIDS and Cl- replacement increased action potential duration in both single rabbit atrial cells and multicellular rabbit atrial preparations. We conclude that the Ca(2+)-dependent Cl- current is substantially larger than the transient K+ current at physiological rates in the rabbit and is likely to play a more important role in action potential repolarization than the latter current in this tissue in vivo.

N-methyl-D-aspartate receptors are implicated in hyperresponsiveness following naloxone reversal of alfentanil in isolated rat spinal cord

In isolated neonatal rat spinal cord, naloxone administered after an opioid increases a nociceptive-related slow ventral root potential (sVRP) to levels above pre-drug controls. We studied the role of N-methyl-D-aspartate (NMDA) receptors in this phenomenon, which may be related to acute tolerance and to hyperalgesia on antagonist-precipitated withdrawal. Naloxone (200 nM) alone produced no significant effect on sVRP area, while naloxone (560 nM) increased area to 121 +/- 17.7% of control (mean +/- SD). Following 200 nM alfentanil, naloxone (200 nM) was associated with a significant rebound in sVRP area to 138 +/- 18.0% of pre-drug control. Hyperresponsiveness developed within 7 min of initial alfentanil exposure. The non-competitive NMDA antagonist MK-801 (20 nM) had no effect on sVRP area when applied alone; higher concentrations produced irreversible depression. MK-801 (20 nM) co-applied with 200 nM alfentanil blocked the rebound increase in sVRP area following naloxone 200 nM and also the increase following naloxone alone (560 nM). The results suggest that alfentanil induces a rapid NMDA receptor-dependent change in spinal cord neuronal excitability.

The relationship between secondary chromosomal abnormalities and blast transformation in chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a stem cell disorder which progresses from a chronic phase (CP) to an accelerated phase (AP), and/or a blast phase (BP) of myeloid (M) or lymphoid (L) phenotype. This progression is frequently preceded or accompanied by recurring secondary chromosomal abnormalities which are believed to play a role in the transformation. In order to investigate the relationship between the secondary change and the development of BP, we undertook a study using fluorescence in situ hybridization to determine in which cells the secondary abnormalities were present. We observed that in one case of L-BP, the secondary change (trisomy 8) appeared to be in a subclone that was different from the blast cells, as it was absent from the lymphoblasts but present in differentiating erythroid, monocytic and granulocytic cells. In two cases, the secondary change (trisomy 8, extra Ph) probably occurred prior to an acute transforming event as it was present in CP or AP predominantly in differentiated granulocytic or monocytic cells. In one case of M-BP, the secondary change (trisomy 8) probably occurred after the acute transformation, as it appeared in only a subset of the blasts. Lastly, in four cases of L-BP, the secondary change (monosomy 7, extra Ph or hyperdiploidy) was closely associated with the BP as it was present in all of the blasts. The findings indicate that some secondary abnormalities may be directly related to the development of BP and may provide clues to the identity of genes responsible for the acute phase transition. Other abnormalities occurring before, or after the acute transformation or in a different subclone from the acute phase blasts, may be more important for denoting genomic instability than for helping to understand the mechanism of blast transformation.

[Observation of immune effect of 5 kinds of Denmark II lyophilized vaccines]

This paper reported five kinds of Denmark II lyophilized vaccines produced by 5 different biological production institutes. Through the double blind randomized trial in newborns after 1 year observation, the results demonstrated that all vaccines possessed the stability of heat tolerance and the 12 week tuberculin conversion rates of all group exceeded to 95%, and 1-year positive maintenance rates were in the range of 88.3%-96.1%, and the average diameter of induration was relatively large; the local reaction belonged to normal range; the swollen-lymph node rate was not high; the immune effect was satisfactory.

Two mutant alleles of mukB, a gene essential for chromosome partition in Escherichia coli

The MukB protein is essential for chromosome partitioning in Escherichia coli and consists of 1484 amino acid residues (170 kDa). We have determined the base changes at the mutated sites of the mukB106 mutant and a newly isolated mutant, mukB33. These mutant mukB genes were each found to carry a single base-pair transition which leads to an amino acid substitution; a serine residue at position 33 was changed to phenylalanine in the case of mukB106, and an aspartic acid residue at position 1201 was changed to asparagine in the case of mukB33.

Class III antiarrhythmic drug action in experimental atrial fibrillation. Differences in reverse use dependence and effectiveness between d-sotalol and the new antiarrhythmic drug ambasilide

BACKGROUND

Drug therapy to maintain sinus rhythm in patients with atrial fibrillation (AF) is limited by adverse effects and inadequate efficacy. There has been an increased interest in the use of class III drugs to treat AF, and several new agents have been developed, but there is little information available about mechanisms of class III drug action in AF. The present study was designed to compare the effects of two class III agents, d-sotalol and ambasilide, in dog models of experimental AF.

METHODS AND RESULTS

A previously developed dog model of sustained vagotonic AF was used to assess the ability of equal loading doses of d-sotalol and ambasilide (2 mg/kg, followed by maintenance infusions), to terminate AF and prevent its induction. At this dose, ambasilide terminated AF in 12 of 12 dogs and prevented AF induction in 10 of 12 dogs; d-sotalol terminated AF in 1 of 8 dogs (P = .001 versus ambasilide) and prevented AF induction in none of 8 dogs (P = .002). An additional dose of d-sotalol (cumulative load, 8 mg/kg) terminated AF in 7 of 8 dogs and prevented induction in 5 of 8 dogs. In an additional 6 dogs with sterile pericarditis and inducible AF, ambasilide prevented AF induction in all 6. An equal dose of d-sotalol (2 mg/kg) failed to suppress AF induction in any dog, but 8 mg/kg of d-sotalol suppressed AF induction in all. Atrial effective refractory period (AERP) was increased by both drugs. However, the effects of d-sotalol on AERP showed strong reverse use dependence, whereas those of ambasilide did not. Neither ambasilide nor d-sotalol significantly altered conduction velocity, and both increased ventricular refractoriness, with d-sotalol once again showing more reverse use dependence. Effective doses of both agents increased AERP and the wavelength for atrial reentry at rapid rates, slowing atrial activation and terminating the arrhythmia.

CONCLUSIONS

The class III drugs d-sotalol and ambasilide terminate AF by increasing AERP and the wavelength for reentry. Ambasilide, which has been reported to block both the rapid and slow components of the delayed rectifier (IKr and IKs), shows less reverse use dependence of effects on refractoriness than the pure IKr blocker d-sotalol, possibly explaining the greater effectiveness of ambasilide at an equal dose level. These results indicate that class III drugs can exhibit different profiles of rate-dependent action on AERP and suggest that it may be possible to develop agents that have more desirable rate-dependent profiles than pure blockers of Ikr.

Actin depolymerization is not involved in phototransduction

The rhabdomeral microvilli in the eyes of invertebrates have a cytoskeletal core (Saibil, 1982; Blest et al., 1982a, b, 1983) of actin (de Couet et al., 1984; Arikawa et al., 1990; Williams, 1991; Caiman & Chamberlain, 1992) which might be involved in phototransduction. Tsukita et al. (1988) suggested that light stimulation triggers the breakdown of the microvillar actin filament complex and that this may play a role in phototransduction. To test their suggestion, we pressure-injected phalloidin into Limulus ventral photoreceptors to prevent actin depolymerization (Cooper, J.A., 1987) and tested to see if this blocked phototransduction. We have previously shown that injected rho-damine-phalloidin brightly labels the microvillar actin filaments in living Limulus ventral photoreceptors for several hours (Feng et al., 1994). In the experiments reported here, phalloidin unconjugated with fluorophore was used, and the final concentration in the cell after many small injections from a pipette containing 10 mg/ml phalloidin was estimated to be 1 mg/ml (1.2 mM). This concentration is 100 times higher than that used in an extracted cellular preparation to stabilize actin (Biegel & Pachter, 1992). Fig. 1 shows that the responses to steps of light at different intensities are normal 1 h after phalloidin injection. Similar results were obtained in two other cells.

The Caulobacter crescentus FlbD protein acts at ftr sequence elements both to activate and to repress transcription of cell cycle-regulated flagellar genes

The flagellar genes (fla genes) in Caulobacter crescentus are organized into a regulatory hierarchy of four levels, I-IV, in which transcription of the class III and class IV genes late in the cell cycle from sigma 54-dependent promoters depends on expression of the class II genes above them. Timing of fla gene expression has been attributed to sequential activation and repression by specific transcription factors. Here we report that purified FlbD activates transcription in vitro from the sigma 54-dependent class III flbG promoter and repress transcription from the class II fliF promoter by binding to ftr (flagellar transcription regulator) sequence elements required for their transcriptional regulation in vivo. The FlbD protein makes symmetrical base-specific contacts at three highly conserved guanine nucleotides in each half site of ftr1 and ftr1* at flbG and the single ftr4 site at fliF. The dual function of FlbD in activation of class III genes and repression of the class II fliF promoter is consistent with a central role of FlbD as a switch protein mediating the transition from level II to level III fla gene expression.

Analysis of amino acid residues in the H5-H6 transmembrane and extracellular domains of Na,K-ATPase alpha subunit identifies threonine 797 as a determinant of ouabain sensitivity

Several amino acid residues of the alpha subunit of the Na,K-ATPase have been identified which alter ouabain sensitivity. These residues are located in the N-terminal half of the alpha 1 subunit suggesting that this portion of the molecule may represent the binding site for cardiac glycosides. However, not all extracellular and transmembrane regions have been investigated, including the H5-H6 membrane-spanning region. To determine if this region of the alpha subunit contributes to ouabain sensitivity, amino acids which have the potential to form hydrogen bonds were substituted with alanine, a non-hydrogen-bonding amino acid. cDNAs encoding enzyme containing these individual amino acid replacements were expressed in ouabain-sensitive HeLa cells, and the ability of the altered enzymes to confer ouabain resistance was examined. Nineteen amino acid substitutions were investigated. T797A (Thr 797 to Ala) was the only substitution which conferred ouabain resistance to sensitive HeLa cells. Three additional substitutions at this position (T797V, T797S, and T797D) were generated in order to examine the effects of the replacements of Thr 797 on ouabain inhibition of Na,K-ATPase activity. The T797V substitution conferred ouabain resistance, but T797S and T797D substitutions did not. The ouabain-resistant cell lines expressing the T797A and T797V substitutions exhibited Na,K-ATPase activity that was 60 and 70 times more resistant to ouabain than the endogenous HeLa or sheep enzymes. The absence of a hydroxyl group at amino acid 797 may be responsible for the reduced sensitivity of the enzyme with substitutions at this position.(ABSTRACT TRUNCATED AT 250 WORDS)

New killing system controlled by two genes located immediately upstream of the mukB gene in Escherichia coli

The nucleotide sequence was determined of the region upstream of the mukB gene of Escherichia coli. Two new genes were found, designated kicA and kicB (killing of cell); the gene order is kicB-kicA-mukB. Promoter activities were detected in the regions immediately upstream of kicB and kicA, but not in front of mukB. Gene disruption experiments revealed that the kicA disruptant was nonviable, but the kicB-disrupted mutant and the mutant lacking both the kicB and kicA genes were able to grow. When kicA disruptant cells bearing a temperature-sensitive replication plasmid carrying the kicA+ gene were grown at 30 degrees C and then transferred to 42 degrees C, the mutant cells gradually lost colony-forming ability, even in the presence of a mukB+ plasmid. Rates of protein synthesis, but not of RNA or DNA synthesis, fell dramatically during incubation at 42 degrees C. These results suggested that the kicB gene encodes a killing factor and the kicA gene codes for a protein that suppresses the killing function of the kicB gene product. It was also demonstrated that KicA and KicB can function as a post-segregational killing system, when the genes are transferred from the E. coli chromosome onto a plasmid.

Effect of cholinesterase inhibition in vitro by huperzine analogs

Huperzine (Hup) A and B were first discovered and studied by Chinese. Fourteen analogs of Hup were tested for their anticholinesterase (anti-ChE) activity by colorimetric method using rat erythrocyte membrane and serum as enzyme sources. Hup-A showed the highest anti-AChE potency. The anti-BuChE activity of (-)dihydro and (-)tetrahydro analogs were potent than those of Hup-A. Their anti-AChE activities were comparable to those of physostigmine and galanthamine. Dihydro analog inhibition was of the mixed competitive type with a Ki value of 0.12 mumol.L-1. Tetrahydro analog inhibition was of the competitive type with a Ki value of 0.56 mumol.L-1. They were different from isoflurophate to bond to AChE in a reversible manner.

Biochemical characterization of epidermal growth-factor receptor in Syrian hamster buccal pouch

Binding of [125I]-epidermal growth factor (EGF) to the membrane of the adult hamster buccal pouch was specific and protein concentration dependent, and was significantly higher than that of rat buccal tissue (hamster versus rat; 12.1 +/- 0.9 versus 9.77 +/- 0.22 fmol/mg protein, mean +/- SD, n = 5, p < 0.01). The higher binding was due to a higher receptor number (Bmax). Western blot analysis using anti-EGF receptor antibody revealed four immunoreactive protein bands of 170, 150, 116 and 55 kDa in hamster buccal membrane preparations. In a separate experiment, the EGF concentration in the phosphate-buffered saline extract of the hamster submandibular gland was determined by radioimmunoassay; the level was significantly much lower (p < 0.01) than that of rat or mouse (hamster, rat, mouse; 24.2 +/- 2.6, 123 +/- 17, 5950 +/- 171 ng/g wet tissue; mean +/- SD, n = 3). The findings suggest that hamster buccal pouch is particularly well suited to the study of the biological functions of oral EGF receptor.

Identification of a functional thyroid hormone response element in the upstream flanking region of the human Na,K-ATPase beta 1 gene

The human Na,K-ATPase beta 1 subunit gene promoter activity is stimulated by thyroid hormone (T3) in the human intestinal Caco-2 cells. To identify potential cis-acting transcriptional regulatory elements involved in this process, chimeric plasmids containing varying lengths of the 5' flanking region of the human beta 1 Na,K-ATPase gene linked to the firefly luciferase reporter gene were introduced into Caco-2 cells by transient transfection. Analysis of T3-regulated luciferase activity of cells carrying these plasmids, and subsequent use of site-directed mutagenesis revealed that a region from -459 to -438 (relative to the transcriptional start site) is required for the induction of the beta 1 Na,K-ATPase gene by T3. An oligonucleotide containing this sequence from -465 to -433 confers T3 responsiveness to a heterologous promoter. Gel mobility shift assays showed specific binding of nuclear proteins of Caco-2 cells to this region and immunoreactive T3 receptor was identified in one of these complexes. These data demonstrate that there is a cis-acting thyroid hormone responsive element in the 5' flanking region of the human beta 1 Na,K-ATPase gene and induction of transcription of this gene by T3 involves specific binding of the thyroid hormone receptor to the TRE located at position -459 to -438.

The fate of human peripheral blood lymphocytes after transplantation into SCID mice

Human peripheral blood lymphocytes (hu-PBL) can be adoptively transferred by intraperitoneal injection into mice with severe combined immunodeficiency (SCID). The transplanted lymphocytes can produce immunoglobulin (Ig), respond to antigens, and survive for months in this chimeric model (hu-PBL SCID). However, whether the lymphocytes actually repopulate and reconstitute lymphoid structures and organs has been subject of some debate. To address this question and to characterize the hu-PBL SCID model better, we employed a novel technique for the identification of human cells in xenogeneic mice. We used fluorescence in situ hybridization (FISH) with a biotinylated DNA probe to all human centromeres. We demonstrated that FISH could be used to detect human cells when they accounted for less than 1% of human/mouse cell mixtures; it could also be employed for the identification and localization of individual human cells in tissue sections. By using FISH, we studied 31 SCID mice injected with 1.5 x 10(7)-4 x 10(7) hu-PBL via intravenous (i.v.) or intraperitoneal (i.p.) routes. In the 6 i.v.-injected mice, we found that the human cells were removed from the circulation into the lung within 1 h. In 22 of 25 i.p.-injected animals, 90-3716 micrograms/ml of human IgG was found in the sera at 3 to 13 weeks after transplantation (a.t.). Human cells colonized the peritoneal cavity and persisted for up to 13 weeks a.t. and, in the 12 mice studied, accounted for 4% to 57% of the cells in the peritoneal fluid. However, only rare, isolated human cells were found in the spleen, blood, bone marrow, lung or Peyer's patches. In 7 of 19 mice that received hu-PBL i.p. from Epstein-Barr virus-seropositive donors, we found masses of human cells usually beneath the peritoneal lining but sometimes infiltrating normal tissue. We conclude that FISH offers a simple means for accurate identification of human cells in the xenogeneic mouse. Although there is colonization of the peritoneal cavity in most mice, and development of lymphoid masses in some, there is no reconstitution of lymphoid structures and only minimal engraftment of lymphoid organs by human cells in conventionally-prepared hu-PBL SCID constructs.

Cytogenetic clonality in myelodysplastic syndromes studied with fluorescence in situ hybridization: lineage, response to growth factor therapy, and clone expansion

Clonality in myelodysplastic syndromes (MDS) has been studied with various techniques including glucose-6-phosphate dehydrogenase (G6PD) isoenzyme and cytogenetic analyses, and with molecular techniques such as gene deletion studies and the analysis of restriction fragment-length polymorphisms (RFLP) of X-linked genes. In this study, we investigated the use of fluorescence in situ hybridization (FISH) with a chromosome-specific probe to examine cytogenetic clonality in peripheral blood (PB) cells from three patients with MDS. In each case, trisomy 8 was shown by conventional cytogenetic analysis at the time of the initial diagnosis. By using FISH with a probe for the centromere of chromosome 8, we identified the trisomy in individual PB cells from Wright-stained smears. With this technique, we could determine the cell lineage involved by the trisomy, and through serial analyses we could assess the response of the clonal and nonclonal cells to growth-factor therapy, and the expansion of the trisomic clone over time. In each of the three cases, various proportions of granulocytes, monocytes, eosinophils, and basophils showed trisomy 8 by FISH analysis. In none of the cases did we detect trisomy 8 in lymphocytes. By analysis of PB cells before and during therapy with recombinant granulocyte-macrophage colony-stimulating factor (GM-CSF), we found that GM-CSF stimulated both trisomic and disomic cells. During a 1-year period of sequential study, we detected an abrupt increase in the percentage of trisomic cells in one patient, a stable percentage in another, and a slowly increasing percentage in the third. The abrupt increase in the first patient preceded a transformation to a more acute phase by 2 months. We conclude that FISH analysis of PB cells of patients with MDS offers an additional approach to the study of clonality in this disorder. In some cases this analysis may provide a useful and simple means of assessing response to therapy and progression of disease.

The polyomavirus enhancer activates chromatin accessibility on integration into the HPRT gene

Recent studies suggest that enhancers may increase the accessibility of chromatin to transcription factors. To test the effects of a viral enhancer on chromatin accessibility, we have inserted minigenes with or without the polyomavirus enhancer into the third exon of the hypoxanthine phosphoribosyltransferase (HPRT) gene by homologous recombination and have prepared high-resolution maps of gene accessibility by using a novel polymerase chain reaction assay for DNase I sensitivity. In its native state, we find that the HPRT gene has low sensitivity to DNase I in fibrosarcoma cells. Insertion of the polyomavirus enhancer and neo reporter gene into exon 3 confers altered HPRT DNase I sensitivity for several kilobases on either side of the enhancer. The changes in DNase I sensitivity peak near the enhancer and decline with distance from the enhancer. The increase in HPRT DNase I sensitivity persisted when the tk promoter was deleted from the inserted construct but disappeared when the enhancer was deleted. These experiments identify the polyomavirus enhancer as a cis-acting initiator of chromatin accessibility.

Clinical evaluation of radioimmunoimaging with 131I-C0C183B2 monoclonal antibody against ovarian carcinoma by intraperitoneal injection

Forty-eight cases subjected to radioimmunoimaging (RII) by intraperitoneal injection with 131I-C0C183B2 monoclonal antibody (MAb) prepared in our laboratory were studied. Thirteen of 14 cases of proved primary ovarian carcinoma were positive. In 11 follow-up cases of ovarian carcinoma after initial surgery and chemotherapy, 5 recurrences were positive and 6 cases without recurrence were negative; all were confirmed histopathologically after a second operation. One false negative was ovarian mucinous adenocarcinoma, which also negatively stained with C0C183B2 by the peroxidase anti-peroxidase method. Twenty of 23 cases of nonepithelial or metastatic carcinoma of the ovary, benign tumors, and benign diseases were negative. The sensitivity and specificity were 94.7 and 89.7%, respectively. If patients had complications with ascites, the MAb which positively stained with the cancer cells in the ascites was chosen for RII. For follow-up cases PAP staining with the tumor tissue from the initial surgery and the MAb should be done before RII. These are the principal factors that increase the positive rate and accuracy of RII. The intraperitoneal route seems to be a valuable method for clinical staging and tumor localization as well as for follow-up use.

Role of phosphorylated metabolic intermediates in the regulation of glutamine synthetase synthesis in Escherichia coli

Transcription of the Ntr regulon is controlled by the two-component system consisting of the response regulator NRI (NtrC) and the kinase/phosphatase NRII (NtrB), which both phosphorylates and dephosphorylates NRI. Even though in vitro transcription from nitrogen-regulated promoters requires phosphorylated NRI, NRII-independent activation of NRI also occurs in vivo. We show here that this activation likely involves acetyl phosphate; it is eliminated by mutations that reduce synthesis of acetyl phosphate and is elevated by a mutation expected to cause accumulation of acetyl phosphate. With purified components, we investigated the mechanism by which acetyl phosphate stimulates glutamine synthetase synthesis. Acetyl phosphate, carbamyl phosphate, and phosphoramidate but not ATP or phosphoenolpyruvate acted as substrates for the autophosphorylation of NRI in vitro. Phosphorylated NRI produced by this mechanism exhibited the properties associated with NRI phosphorylated by NRII, including the activated ATPase activity of the central domain of NRI and the ability to activate transcription from the nitrogen-regulated glutamine synthetase glnAp2 promoter.

An altered repertoire of fos/jun (AP-1) at the onset of replicative senescence

With multiple divisions in culture, normal diploid cells suffer a loss of growth potential that leads to replicative senescence and a finite replicative capacity. Using quantitative RT-PCR, we have monitored mRNA expression levels of c-fos, c-jun, JunB, c-myc, p53, H-ras, and histone H4 during the replicative senescence of human fibroblasts. The earliest and the largest changes in gene expression occurred in c-fos and junB at mid-senescence prior to the first slowing in cell growth rates. The basal level of c-fos mRNA decreased to one-ninth that of the early-passage levels, while junB declined to one-third and c-jun expression remained constant. The decline in the basal c-fos mRNA level in mid-senescence should lead to an increase in Jun/Jun AP-1 homodimers at the expense of Fos/Jun heterodimers and may trigger a cascade of further changes in c-myc, p53, and H-ras expression in late-passage senescent fibroblasts.

High-resolution analysis of c-fos chromatin accessibility using a novel DNase I-PCR assay

In our previous study, c-fos chromatin accessibility was assayed using DNase I digestion and Southern blot analysis. This low-resolution mapping of c-fos chromatin accessibility demonstrated that serum stimulation of the c-fos enhancer induces a reversible increase in c-fos DNase I sensitivity and suggested that a 5' to 3' gradient of DNase I sensitivity may form downstream from the c-fos enhancer. To confirm the existence of a 5' to 3' gradient of accessibility, we have recently developed a high-resolution polymerase chain reaction (PCR) assay for DNase I sensitivity. Using this novel DNase I assay, we have reliably detected position- and time-dependent gradients of chromatin accessibility around the c-fos enhancer. These data confirm our earlier results and further support the hypothesis that the changes in c-fos chromatin accessibility originate near the 5' enhancer. As a technique for future examinations of gene structure, our data demonstrate the value of the DNase I-PCR assay for rapidly preparing comprehensive and high-resolution maps of chromatin accessibility for any sequenced genomic region.

[Propagation methods for nutmeg seeds]

The test was conducted on the interrelated factors of germination of Nutmeg seeds. The result indicated that germination occurred fast and exuberantly (up to 88.8%) when the fresh and plump seeds (collected in summer or early autumn) were shown and expedited in clean sand in the complete shade during May-August after being treated with wet sand for 96 hours.

[Gene diagnosis of hemophilia A by PCR]

DNA fragments containing restriction enzyme Bcl I or XbaI polymorphic sites within the gene of coagulation factor VIII were amplified, respectively. Carrier detection and prenatal diagnosis of hemophilia A were performed by analysis of the polymorphisms of the amplified DNA. This is a simple, fast and sensitive technique, especially for prenatal diagnosis with very small amounts of chorionic villi or amniocytes. Four families with hemophilia A were analyzed, and 3 cases at high risk for hemophilia A were diagnosed prenatally.