Expression of foreign gene in mycobacterium regulated by human Mycobacterium tuberculosis heat shock protein 70 promoter

The DNA fragments of 150bp length promoter of human Mycobacterium (M.) tuberculosis heat shock protein (hsp) 70 and 650bp length foreign gene, the Schistosoma japonicum glutathione S-transferase (Sj26GST) gene, were obtained by amplification with polymerase chain reaction. And the 150bp DNA sequence upstream initiation codon ATG of the human M. tuberculosis hsp 70 promoter that contains the sequence TTGAG and ATCATA which consensus with E. coli promoter's -35 and -10 region respectively, as well as ribosome binding site GGAGG at position -12--8 upstream the ATG were determined by SangerDideoxyribonucleotide-mediated chain-termination method. Then, the human M. tuberculosis hsp70 promoter and Sj26GST cDNA were cloned into E. coli-mycobacteria shuttle plasmid pBCG- 2000 to construct E. coli-Mycobacterium expression shuttle plasmid pBCG- Sj26 that can express Sj26GST gene. The M. smegmatis were electroporated and the positivecolonies were selected by kanamycin. The M. smegmatis containing the vector pBCG-Sj26 can be induced by heating and hydrogen peroxide (H2O2) to express GST. The molecular weight of the recombinant GST (rGST) was 26,000. The rGST contents that were about 10 percent of the total bacterial protein were analyzed by density scanning after running SDS-PAGE. This study would provide scientific evidences for application of hsp70 promoter in expressing foreign gene in mycobacterium and development of mycobacterium as multiple-valent vectoral vaccine.

The purified Bacillus subtilis tetracycline efflux protein TetA(L) reconstitutes both tetracycline-cobalt/H+ and Na+(K+)/H+ exchange

Recent work has suggested that the chromosomally encoded TetA(L) transporter of Bacillus subtilis, for which no physiological function had been shown earlier, not only confers resistance to low concentrations of tetracycline but is also a multifunctional antiporter protein that has dominant roles in both Na(+)- and K(+)-dependent pH homeostasis and in Na+ resistance during growth at alkaline pH. To rigorously test this hypothesis, TetA(L) has been purified with a hexahistidine tag at its C terminus and reconstituted into proteoliposomes. The TetA(L)-hexahistidine proteoliposomes exhibit high activities of tetracycline-cobalt/H+, Na+/ H+, and K+/H+ antiport in an assay in which an outwardly directed proton gradient is artificially imposed and solute uptake is monitored. Tetracycline uptake depends on the presence of cobalt and vice versa, with the cosubstrates being transported in a 1:1 ratio. Evidence for the electrogenicity of both tetracycline-cobalt/H+ and Na+/H+ antiports is presented. K+ and Li+ inhibit Na+ uptake, but there is little cross-inhibition between Na+ and tetracycline-cobalt uptake activities. The results strongly support the conclusion that TetA(L) is a multifunctional antiporter. They expand the roster of such porters to encompass one with a complex organic substrate and monovalent cation substrates that may have distinct binding domains, and provide the first functional reconstitution of a member of the 14-transmembrane segment transporter family.

Ion channel blockers in the treatment of chronic heart failure

Strategies for pharmacological treatment of chronic congestive heart failure (CHF) are discussed from the viewpoint of cardiac ion channel modulations. It remains controversial as to whether Na channel blockers, which are the most effective drugs to suppress ventricular arrhythmias, can improve the prognosis of chronic CHF. As far as recent knowledge of interactions between the Na channel and its blocker is concerned, lidocaine-like agents such as mexiletine, which inhibit the Na channel current by binding to the channel in the inactivated state, are recommended because they can suppress premature ventricular contractions without prolongation of QRS complexes of sinus beats. To develop a new agent for the treatment of chronic CHF, we extracted the common features of electropharmacologic actions shared by amiodarone and vesnarinone, both of which have been reported to reduce the mortality of patients with chronic CHF. It is concluded that increases in the action potential duration (APD) of ventricular muscle mediated through an inhibition of the delayed rectifier K channel (IK channel) and a reduction of sinus node firing through an inhibition of L type Ca channel in addition to IK channel inhibition, are essential for the treatment of chronic CHF.

[The research of radioimmunoassay using double Abs for bradykinin]

Bradykinin (BK) is a potent vasodilative substance, and plays great physiological and pathological roles in animals and human beings. To measure the quantity of BK, the radioimmunoassay (RIA) has been devised, but the traditional RIA method has certain defects, such as presence of numerows interfering factors and errors and time consuming. Now, we produce anti-BK serum in rabbits by using BK-ovalbumin conjugate as an immunogen, and the 125I labeled Tyr8-BK by using a modified chloramine-T method. High specific activity has been obtained after purification with DEAE-Sephadex A-25 column chromatography. We use the donkey anti-rabbit Ab and PEG 6000 to separate the bound from the free 125I-Tyr8-BK. The limitation range of standard curve is from 25 to 1600 pg, NSB is 3.1% affinity constant (K) is 0.8 x 10(10) L/mol, and there is no significant interference with other biological BK analogues. The blood samples are treated by adding Polybrene (inhibitor) and PEG 6000 to deposit the big serum proteins in order to reduce the disturbing substances. This method has been shown to be a sensitive, specific, reliable, simple and convenient measure of the serum BK level. By this method, the serum BK quantities in men, women and rats are respectively 1584 +/- 347 pg/ml, 1642 +/- 302 pg/ml and 1805 +/- 225 pg/ml, the recycling rate is 95%, the intergroup CV is 5.0% and outergroup CV = 9.2%.

Prostaglandin F2 alpha induces cardiac myocyte hypertrophy in vitro and cardiac growth in vivo

Several prostaglandins [prostaglandin (PG) A2, -B2, -D2, -E2, -F2 alpha, and -I2 and carbaprostacyclin] and the thromboxane analogue U-46619 were analyzed for the ability to induce hypertrophy of rat neonatal cardiac ventricular myocytes. Myocyte hypertrophy was induced specifically by PGF2 alpha. Myocytes exposed to this prostanoid in culture increased in size and protein content. The contractile fibrils within the cells became organized into parallel arrays, and the cells tended to cluster and beat spontaneously. PGF2 alpha also induced the expression of c-fos, atrial natriuretic factor (ANF), and alpha-skeletal actin in these cells. The effects of PGF2 alpha were compared with several known cardiac myocyte hypertrophy factors (phenylephrine, endothelin-1, leukemia inhibitory factor, cardiotrophin-1, and angiotensin II). PGF2 alpha was found to be intermediate in potency among the factors but induced a level of ANF production that was approximately 10-fold higher than any of the other effectors. Responsiveness to PGF2 alpha was not limited to neonatal cardiocytes. Ventricular myocytes isolated from adult rats also responded specifically to PGF2 alpha with a morphological change similar to that observed with phenylephrine and by producing ANF. In rats, chronic administration of fluprostenol, a potent agonist analogue of PGF2 alpha, resulted in a dose-dependent increase in heart weight- and ventricular weight-to-body weight ratios. The amount of PGF2 alpha extractable from the hearts of rats with cardiac hypertrophy induced by myocardial infarction was also found to be greater than that in sham-operated control rats. These results indicate that PGF2 alpha may play an important role in inducing cardiac hypertrophy.

Intracellular IL-1beta is an inhibitor of Fas-mediated apoptosis

Fas-mediated apoptosis has been shown to be mediated by the IL-1beta converting enzyme (ICE) pathway. To determine the relationship between ICE and its substrate IL-1beta, we examined six human cell lines for susceptibility to Fas-mediated apoptosis and Fas induction of ICE-like activity. The human B lymphoblastoid cell line SKW6.4 and the human T lymphoma cell lines Jurkat, CEM-6, H-9, and MOLT4 were susceptible to Fas-mediated apoptosis, whereas the human promyelocytic leukemia cell line HL-60 was resistant to Fas-mediated apoptosis. ICE mRNA was highly expressed in SKW6.4, H-9, and HL-60 cells, and ICE-like activity increased during Fas-mediated apoptosis in SKW6.4 cells. In contrast, IL-1beta mRNA was highly expressed only in HL-60 cells. Acetyl-Tyr-Val-Ala-Asp-chloromethylketone, a tetrapeptidyl inhibitor of ICE, prevented Fas-mediated apoptosis strongly in SKW6.4 and H-9 cells but weakly or marginally in other cells. To examine whether intracellular IL-1beta is a proteolytic substrate or an endogenous competitive inhibitor against other substrates for Fas-ICE-mediated apoptosis in SKW6.4 cells, we established precursor IL-1beta transfectant clones using SKW6.4 cells. We demonstrated that stably transfected SKW6.4 cells expressing precursor IL-1beta, but not cells transfected with the empty vector, exhibited resistance to Fas-mediated apoptosis due to competitive inhibition of ICE-like activity, which was associated with increased cleavage of precursor IL-1beta to mature IL-1beta. These results suggest that Fas-mediated apoptosis is mediated by ICE cleavage of proteolytic substrates other than IL-1beta and that IL-1beta is an endogenous inhibitor of Fas-mediated apoptosis.

Solid state NMR study on the conformation and mobility of n-octadecyl chains in a silane coupling agent attached to the surface of colloidal silica

The surface of colloidal silica of 22 nm and 100 nm in diameter has been modified with a silane coupling agent, n-octadecyltriethoxysilane. The solid state 13C NMR spectrum shows surprisingly that the covalently bonded n-octadecyl chains on the silica surface adopt largely extended all-trans conformation. By increasing the temperature to 70 degrees C, the trans conformations observed at room temperature can be converted to a disordered state in which the trans and gauche conformers are under rapid exchange (mobile disorder). On cooling to ambient temperature, the trans conformation cannot be recovered and a distribution of chain conformations can be observed, indicating that the disorder has been frozen-in (rigid disorder). Subsequent treatment of the surface modified silica with a second reagent, such as trimethylsilychloride or ethanol reacts with the remaining surface hydroxy groups and causes the n-octadecyl chains to collapse to the mobile, disordered state. The 13C spin-lattice relaxation times for carbon atoms in the all-trans conformation are longer than those in the mobile, disordered chains, indicating that there is more restriction of motion in the trans octadecyl chains. Instead of crystallization of the octadecyl chains on the silica surface, other factors, such as static interactions, might be responsible for the existence of trans conformation in the octadecyl chains.

Intracellular IL-1beta is an inhibitor of Fas-mediated apoptosis

Fas-mediated apoptosis has been shown to be mediated by the IL-1beta converting enzyme (ICE) pathway. To determine the relationship between ICE and its substrate IL-1beta, we examined six human cell lines for susceptibility to Fas-mediated apoptosis and Fas induction of ICE-like activity. The human B lymphoblastoid cell line SKW6.4 and the human T lymphoma cell lines Jurkat, CEM-6, H-9, and MOLT4 were susceptible to Fas-mediated apoptosis, whereas the human promyelocytic leukemia cell line HL-60 was resistant to Fas-mediated apoptosis. ICE mRNA was highly expressed in SKW6.4, H-9, and HL-60 cells, and ICE-like activity increased during Fas-mediated apoptosis in SKW6.4 cells. In contrast, IL-1beta mRNA was highly expressed only in HL-60 cells. Acetyl-Tyr-Val-Ala-Asp-chloromethylketone, a tetrapeptidyl inhibitor of ICE, prevented Fas-mediated apoptosis strongly in SKW6.4 and H-9 cells but weakly or marginally in other cells. To examine whether intracellular IL-1beta is a proteolytic substrate or an endogenous competitive inhibitor against other substrates for Fas-ICE-mediated apoptosis in SKW6.4 cells, we established precursor IL-1beta transfectant clones using SKW6.4 cells. We demonstrated that stably transfected SKW6.4 cells expressing precursor IL-1beta, but not cells transfected with the empty vector, exhibited resistance to Fas-mediated apoptosis due to competitive inhibition of ICE-like activity, which was associated with increased cleavage of precursor IL-1beta to mature IL-1beta. These results suggest that Fas-mediated apoptosis is mediated by ICE cleavage of proteolytic substrates other than IL-1beta and that IL-1beta is an endogenous inhibitor of Fas-mediated apoptosis.

Endoscopic stenting in the management of biliary stones

INTRODUCTION

Endoscopic sphincterotomy and stenting are established modes of treatment in the management of bile duct stones and cholangitis. It is the first choice of treatment when the patients are elderly and have other medical conditions rendering them unfit for surgery.

AIMS

We studied the immediate and long-term outcome of endoscopic stenting in patients who underwent Endoscopic Retrograde Cholangiopancreatography (ERCP) for ductal stones.

PATIENTS AND METHODS

From January 1990 to December 1992, 366 patients had ERCP done for biliary stone disease. Fifty-five of these patients received a 10 French biliary stent for the treatment of bile duct stones. Most of these patients (60%) had an advanced age of more than 70 years and 45% had co-existing medical conditions rendering them high risk for surgery. Ninety-one percent had stones greater than 1.2 cm in diameter and 82% had multiple stones.

RESULTS

Eighty-nine percent of the patients had relief of jaundice and cholangitis resolved in 96% of the patients after stenting. None required immediate surgery after ERCP. Temporary bile drainage was achieved in 19 patients who went for surgery at a later date when they became more stable. Twenty-nine patients were on long-term follow-up for a mean period of 13 months. Nineteen patients still have their stents in place and remained well. The stents were repeatedly changed in 15 patients after an average duration of 5.5 months. Late complications were cholangitis in 2 patients and stent migration in one patient. There was no related mortality. In 5 patients, the stones have either disappeared spontaneously or become smaller and have been removed at subsequent ERCP.

CONCLUSION

Endoscopic stenting is a valuable alternative to surgical bile duct exploration. It can be the definitive mode of treatment for large or multiple bile duct stones in the elderly and patients with multiple medical problems who are unfit for surgery.

[Effects of gossypol acetic acid on human ejaculated sperm Ca2+ influx and rat vas deferens contraction action]

It has been reported that gossypol acetic acid (GAA) inhibits sperm motility and calcium plays an important role in regulating the function of the sperm flagella. In order to explore the mechanism by which GAA inhibits sperm motility, the effects of GAA on human ejaculated sperm Ca2+ influx and isolated rat vas deferens contraction action were studied. The results showed that GAA inhibited sperm Ca2+ influx in a dose-dependent manner, and breaked the dynamic equilibrium of sperm internal and external Ca2+ gradient concentrations. It may be one of important mechanism by which GAA inhibits sperm motility. But GAA exerts no effect on the high K+ induced contraction of smooth muscle of isolated rat vas deferens. It is likely that GAA has selective action on the sperm membrane of the rats.

Autoimmune disease results from multiple interactive defects in apoptosis induction molecules and signaling pathways

Activation induced cell death (AICD) plays a critical role in eliminating autoimmune cells and limiting inflammation after activation. The two major signaling molecules for AICD are the Fas and TNF-R pathways of apoptosis. Defective Fas apoptosis in lpr/lpr mice results in a compensatory increase in TNF-R/TNF-mediated apoptosis. TNF/TNF-R has been shown to be a compensatory pathway of apoptosis in T cells and macrophages of lpr/lpr mice. Therefore, early production of TNF/TNF-R limit an immune response by inducing AICD in the absence of an intact Fas/Fas ligand apoptosis pathway. However, increased TNF production in lpr mice also lead to increased susceptibility to septic shock and autoimmune disease such as arthritis. Therefore TNF production during an inflammatory response can downmodulate this response, but this also results in the failure to downmodulate TNF production leading to septic shock and arthritis. A second pathway of AICD is mediated by Nur77 after T cell stimulation through the CD3 molecule. Mice with defective Nur77 signaling undergo AICD using the Fas-Fas ligand pathway to eliminate autoreactive T cells. A third defect of AICD is observed in HCP-mutant me/me (motheaten) mice which develop autoimmune disease related to defective Fas apoptosis signaling. Therefore, multiple interactive pathways play a role in limiting development of autoimmunity.

Pseudocyst formation by adenoid cystic carcinoma cells in collagen gel culture and in SCID mice

In order to reconstruct the characteristic three-dimensional architecture of adenoid cystic carcinoma, we cultured ACC2 cells, a cell system established from a human adenoid cystic carcinoma of the palate, in collagen gel matrix and transplanted them in SCID mice. In the collagen gel culture, the cells formed spherical colonies measuring 75.6 +/- 14.6 microns in diameter by 6 days after seeding. The tumor cell nests contained vacuolar structures that were immunopositive for heparan sulfate proteoglycan, type III collagen, type IV collagen, and fibronectin. The rim of the nests was argyrophilic and immunopositive for type I collagen, type IV collagen, laminin, and fibronectin. Transplants of ACC2 cells in SCID mice grew to form tumor masses in which pseudocysts were formed. The results indicate that our collagen gel culture system provides physiological conditions for ACC2 cells to secrete particular extracellular matrix molecules and form pseudocystic spaces.

Dynamics and energetics of scallop locomotion

A dynamic model for a swimming scallop was developed which integrates the mechanical properties of the hinge ligaments, valve inertia, the external fluid-flow reaction, the fluid pressure in the mantle cavity and the muscle contraction. Kinematic data were recorded for a swimming Placopecten magellanicus from high-speed film analysis. Dynamic loading experiments were performed to provide the required mechanical properties of the hinge for the same species. The swimming dynamics and energetics based on data from a 0.065 m long Placopecten magellanicus at 10 °C were analyzed. The main conclusions are as follows. 1. The mean period of a clapping cycle during swimming is about 0.28 s, which can be roughly divided into three equal intervals: closing, gliding and opening. The maximum angular velocity and acceleration of the valve movements are about 182 degrees s-1 and 1370 degrees s-2, respectively. 2. The hysteresis loop of the hinge was found to be close to an ellipse. This may be represented as a simple Voigt body consisting of a spring and dashpot in parallel, with a rotational stiffness of 0.0497 N m and viscosity coefficient of 0.00109 kg m2 s-1 for the 0.065 m long Placopecten magellanicus. 3. The external fluid reaction has three components, of which the added mass is about 10 times higher than the mass of a single valve, and the flow-induced pseudo-viscosity compensates for nearly half of the hinge viscosity for the 0.065 m long Placopecten magellanicus. 4. The locomotor system powered by the muscle can be divided into two subsystems: a pressure pump for jet production and a shell-hinge/outer-fluid oscillator which drives the pumping cycle. The dynamics of the oscillator is determined predominantly by the interaction of the external fluid reaction and the hinge properties, and its resonant frequency was found to be close to the swimming frequencies. 5. The momentum and energy required to run the oscillator are negligibly small (about 1 % for the 0.065 m long Placopecten magellanicus) compared with that for the jet. Almost all the mechanical energy from muscle contraction is used to perform hydrodynamic work for jet production. Thus, the Froude efficiency of propulsion in scallops is nearly the same as the entire mechanical efficiency of the locomotor system. This could be a fundamental advantage of jet propulsion, at least for a scallop. 6. The estimated maximum muscle stress is about 1.06x10(5) N m-2, the cyclic work is 0.065 J and power output is 1.3 W. Using an estimate of the mass of an adductor muscle, the work done by the muscle per unit mass is 9.0 J kg-1 and the peak power per unit mass is 185 W kg-1. 7. The time course of the force generation of the contracting adductor muscle is basically the same as that of the hydrodynamic propulsive force.

The role of programmed cell death as an emerging new concept for the pathogenesis of autoimmune diseases

Activation-induced apoptosis is a primary mechanism for downmodulation of an immune response leading to immune homeostasis and deletion of T cells with specificities which may be harmful. These include deletion of T cells with self-specificities (autospecific) and excessively high affinity for foreign antigen which may lead to an excessively heightened immune response and septic shock. Surface molecules involved in activation-induced apoptosis involve Fas and Fas ligand (FasL), as well as the T-cell receptor (TCR) which modulates the expression and function of these molecules. Fas signaling mechanisms include the hematopoietic cell phosphatase (HCP) and sphingomyelinase, while TCR-signaling mechanisms include Nur77 and fyn kinase and unknown molecules that modulate expression of FasL. Apoptosis signals are further modulated by inhibitors or inducers of apoptosis including Bcl-2, p53, and interleukin-1 beta converting enzyme (ICE). Further understanding of the interaction of these molecules in autoimmune disease may lead to more specific therapies for immunosuppression tailored to the genetic or environmentally induced, activation-induced apoptosis defect in patients.

A novel protein tyrosine phosphatase expressed in lin(lo)CD34(hi)Sca(hi) hematopoietic progenitor cells

Stem cells are capable of extensive self-renewal in the absence of differentiation. The maintenance of this undifferentiated state occurs despite the fact that this cell is exposed to a milieu that is rich in a variety of growth and differentiation factors. A unifying feature of such hematopoietic factors is that they mediate their effects through the phosphorylation of tyrosine residues by various cellular kinases. Therefore, one mechanism that might inhibit such differentiation signals in the self-renewing stem cell is the dephosphorylation of tyrosine residues by protein tyrosine phosphatases (PTPs). We have thus investigated the types of tyrosine phosphatases expressed by murine embryonic lin(lo)CD34hiSca(hi) hematopoietic progenitor cells by using a consensus polymerase chain reaction (PCR) approach. Although many known tyrosine phosphatases were detected using this method, a novel PTP related to the previously described PTP PEST type enzymes, murine PTP PEP and murine/human PTP PEST, was also observed. Cloning of the full-length cDNA encoding this enzyme showed that it was indeed a novel new member of this family, with an amino terminal tyrosine phosphatase domain followed by a region rich in serine, threonine, and proline. The carboxy terminus of this novel PTP contained a short sequence that was homologous to a region of the murine PTP PEP that was involved with nuclear localization. Bacterial expression of the phosphatase domain showed that this enzyme could efficiently dephosphorylate tyrosines in vitro. Analysis of the expression of the novel nuclear PTP by quantitative PCR showed that the transcript disappeared as the lin(lo)CD34hiSca(hi) cells differentiated in the presence of interleukin-1, interleukin-3, erythropoietin, and granulocyte-macrophage colony-stimulating factor. In agreement with its potential role in the hematopoietic progenitor cell, this novel PTP was expressed at a barely detectable level in a very limited subset of adult tissues. However, analysis of several murine hematopoietic progenitor cell lines, but not of a differentiated T-cell line, showed a high level of expression of the novel PTP. These data suggest that this novel phosphatase may play a critical role in the maintenance of the undifferentiated state of the hematopoietic stem cell.

Changes in action potentials and ion currents in long-term cultured neonatal rat ventricular cells

A primary culture of neonatal ventricular myocytes isolated from day-old rats was established for investigating the changes in action potentials and ion currents over long periods. Cells at days 5 and 15 in culture were studied. These changes in vitro were compared with those in situ derived from the age-matched freshly isolated cells. During primary culture, quiescent cells demonstrated shortening of action potential durations (APD) resembling the developmental changes observed in situ. The beating cultured cells were not associated with APD shortening. Despite constant current amplitudes, the densities of Ca2+ currents (ICa) decreased in the quiescent cultures at later ages as a result of cell enlargement. ICa densities were maintained in the beating cultured and freshly isolated cells. Acceleration in the inactivation of ICa was observed during developments both in vitro and in situ. In addition, the densities of transient outward currents (Ito) tripled and doubled in the quiescent and beating cells during 15-day cultures. However, Ito in beating cultured cells made less contribution to APD in contrast to the quiescent cultured and freshly isolated myocytes. These findings demonstrate that electrophysiological properties differ between two types of long-term cultured cells. ICa densities remained constant in the beating cultures, suggesting that cell beating may be required for the maintenance of ICa density in developing cardiomyocytes.

The inversion of the exponential Radon transform for quantitative brain SPECT

The mathematical derivation for the inversion of the exponential Radon transform is presented and the implementation of the inversion is detailed. The inversion can be verified and implemented by the readers for practical applications, such as for quantitative reconstruction of brain SPECT (single-photon emission computed tomography).

Differential effects of MS-551 and E-4031 on action potentials and the delayed rectifier K+ current in rabbit ventricular myocytes

OBJECTIVE

The frequency-dependent effects of MS-551 on the action potential duration (APD) and the underlying ionic mechanisms were investigated in comparison with those of E-4031.

METHODS

Whole-cell clamp techniques were used to study action potentials and ionic currents in enzymatically isolated rabbit ventricular myocytes.

RESULTS

The frequency-response obtained within the range of 0.1 to 3.3 Hz was different for MS-551 and E-4031. The APD prolongation by MS-551 (10 microM) was significant at 0.5-3.3 Hz, whereas that by E-4031 (1 microM) was significant at 0.1-1.0 Hz. The prolongation by MS-551 (10 microM) of APD of a test action potential, which was preceded by a train of 1.0 Hz stimulation, decreased progressively as the rest duration increased, whereas that by E-4031 (1 microM) remained at the same level. Both MS-551 (10 microM) and E-4031 (1 microM) significantly decreased IK, but showed no effects on the transient outward current (Ito) and the inward rectifier K+ current (IKl). The development of the block on IK and the recovery from the block by MS-551 were voltage dependent. At a holding potential of -50 mV, MS-551 reduced the tail current to a similar extent (21-34%, n = 6) across all the tested durations of the depolarizing pulses to +10 mV, whereas at -75 mV, the intensity of the block progressively increased as the durations of depolarizing pulses were prolonged. The recovery from the block by MS-551 was absent at -50 mV, but occurred at -75 mV with a time constant of 577 +/- 179 ms (n = 6). The development of the block on IK by E-4031 was voltage and time independent. No recovery from the block was observed for E-4031 at either -50 or -75 mV.

CONCLUSIONS

These findings suggest that MS-551 produces frequency-dependent class III action, presumably due to the voltage-dependent binding and unbinding to the IK channels. The reverse frequency dependence of class III action by E-4031 cannot be explained by the effects on IK.

Common core sequences are found in skeletal muscle slow- and fast-fiber-type-specific regulatory elements

The molecular mechanisms generating muscle diversity during development are unknown. The phenotypic properties of slow- and fast-twitch myofibers are determined by the selective transcription of genes coding for contractile proteins and metabolic enzymes in these muscles, properties that fail to develop in cultured muscle. Using transgenic mice, we have identified regulatory elements in the evolutionarily related troponin slow (TnIs) and fast (TnIf) genes that confer specific transcription in either slow or fast muscles. Analysis of serial deletions of the rat TnIs upstream region revealed that sequences between kb -0.95 and -0.5 are necessary to confer slow-fiber-specific transcription; the -0.5-kb fragment containing the basal promoter was inactive in five transgenic mouse lines tested. We identified a 128-bp regulatory element residing at kb -0.8 that, when linked to the -0.5-kb TnIs promoter, specifically confers transcription to slow-twitch muscles. To identify sequences directing fast-fiber-specific transcription, we generated transgenic mice harboring a construct containing the TnIs kb -0.5 promoter fused to a 144-bp enhancer derived from the quail TnIf gene. Mice harboring the TnIf/TnIs chimera construct expressed the transgene in fast but not in slow muscles, indicating that these regulatory elements are sufficient to confer fiber-type-specific transcription. Alignment of rat TnIs and quail TnIf regulatory sequences indicates that there is a conserved spatial organization of core elements, namely, an E box, a CCAC box, a MEF-2-like sequence, and a previously uncharacterized motif. The core elements were shown to bind their cognate factors by electrophoretic mobility shift assays, and their mutation demonstrated that the TnIs CCAC and E boxes are necessary for transgene expression. Our results suggest that the interaction of closely related transcriptional protein-DNA complexes is utilized to specify fiber type diversity.

Evaluation of the Technicon Immuno 1 free thyroxine assay

The Technicon Immuno 1 free thyroxine (fT4) assay, a modified two-step procedure that is fully automated on a random access analyzer, was evaluated-at two clinical sites. The method had excellent precision and correlated well overall with three other estimates of free thyroxine: free thyroxine index (FTI) measured on the Immuno 1; the Abbott IMx fT4 assay (Abbott Park, IL); and the Clinical Assays two-step manual fT4 assay. Using a combination of thyrotropin and FTI assay results as a "gold standard" for defining thyroid status, the Immuno 1 fT4 method had a sensitivity of 100% and specificity of 98.3% for hyperthyroidism, versus 93.8% and 99.3%, respectively, for hypothyroidism. In conclusion, the Immuno 1 fT4 assay is useful in screening for thyroid disease.

Chromosomal tetA(L) gene of Bacillus subtilis: regulation of expression and physiology of a tetA(L) deletion strain

Deletion of the tetA(L) chromosomal region of Bacillus subtilis in a strain designated JC112 increased the strain's sensitivity to low tetracycline concentrations. It also resulted in phenotypic changes that correlate with the previously found role of TetA(L) in mediating electrogenic NA+/H+ antiport. Growth of JC112 was impaired relative to that of the wild type at both pH 7.0 and 8.3; Na(+)- and K(+)-dependent pH homeostases were impaired at alkaline pH. The phenotype of JC112 was complemented by plasmid-borne tetA(L) and related tet(K) genes; the antiport activity conferred by the tet(K) gene had an apparently higher preference for K+ over Na+ than that conferred by tetA(L). The data were consistent with TetA(L) being the major Na+(K+)/H+ antiporter involved in pH homeostasis in B. subtilis as well as a significant Na+ extrusion system. The phenotype of JC112 was much more pronounced than that of an earlier transposition mutant, JC111, with a disruption in the putative tetA(L) promoter region. Northern (RNA) blot analysis of tetA(L) RNA from wild-type and JC111 strains revealed the same patterns. That JC111 nevertheless exhibited some Na+ and alkali sensitivity may be accounted for by disruption of regulatory features that, in the wild type, allow increased tetA(L) expression under specific conditions of pH and monovalent cation concentration. Evidence for several different regulatory effects emerged from studies of lacZ expression from the transposon of JC111 and from a tetA(L)-lacZ translational fusion introduced into the amyE locus of wild-type and JC112 strains.

Pax3 modulates expression of the c-Met receptor during limb muscle development

Pax3 is a transcription factor whose expression has been used as a marker of myogenic precursor cells arising in the lateral somite destined to migrate to and populate the limb musculature. Accruing evidence indicates that the embryologic origins of axial and appendicular muscles are distinct, and limb muscle abnormalities in both mice and humans harboring Pax3 mutations support this distinction. The mechanisms by which Pax3 affects limb muscle development are unknown. The tyrosine kinase receptor for hepatocyte growth factor/scatter factor encoded by the c-met protooncogene is also expressed in limb muscle progenitors and, like Pax-3, is required in the mouse for limb muscle development. Here, we show that c-met expression is markedly reduced in the lateral dermomyotome of Splotch embryos lacking Pax3. We show that Pax3 can stimulate c-met expression in cultured cells, and we identify a potential Pax3 binding site in the human c-MET promoter that may contribute to direct transcriptional regulation. In addition, we have found that several cell lines derived from patients with rhabdomyosarcomas caused by a t(2;13) chromosomal translocation activating PAX3 express c-MET, whereas those rhabdomyosarcoma cell lines examined without the translocation do not. These results are consistent with a model in which Pax3 modulates c-met expression in the lateral dermomyotome, a function that is required for the appropriate migration of these myogenic precursors to the limb where the ligand for c-met (hepatocyte growth factor/scatter factor) is expressed at high levels.

Analysis of ligase chain reaction products amplified in a silicon-glass chip using capillary electrophoresis

Ligase chain reaction (LCR) is a useful molecular technique for detecting known point mutations. We report the first example of the use of a disposable silicon-glass micro-chip for LCR and the first application of capillary electrophoresis (CE) to analyze samples amplified by LCR in a chip. Silicon-glass chips were manufactured using conventional photolithography and anodic bonding. The chips provide three distinct advantages for LCR: excellent thermal conductivity, a micro reaction volume ( < 10 microliters), and reproducible, low-cost manufacturing. Investigation and quantitation of amplification efficiency of LCR in a chip or in a tube requires an analytical technique that is faster and more convenient than the conventional slab gel methods. Slab gel electrophoresis uses relatively large amounts of sample and is labor-intensive and time-consuming, and thus is unsuitable for the separation and detection of LCR products. In contrast CE requires sample volume (original LCR products) of less than 1 microliter and is therefore well-suited to analysis of the micro-volume reaction mixture from chips. We combined CE with a sensitive laser induced fluorescence (LIF) detection system for the rapid separation and quantitative detection of LCR products amplified from the lacI gene in a silicon-glass chip. Comparative studies were made with LCR between tubes and silicon-glass chips. CE-LIF analysis is ideally suited to examination of micro-LCR amplification with high throughput. The technologies may find medical uses in disease diagnosis and research.

Carbon monoxide: an endogenous modulator of the nitric oxide-cyclic GMP signaling system

Carbon monoxide (CO) is an activator of soluble guanylyl cyclase and is implicated as a neuronal messenger. CO production, nitric oxide synthase (NOS) activity, and guanosine 3',5'-monophosphate (cGMP) levels were quantitated in cerebellar granule cell cultures. Metabolic labeling experiments enabled the direct measurement of neuronal CO production in vitro. CO production is significant, and peaked during early stages of culture. NOS activity and cGMP levels synchronously increased as cells matured. Whereas inhibition of NOS depleted cGMP in mature cultures, inhibitors of CO production potentiated the nitric oxide (NO)-mediated cGMP increase. Exogenous CO at similar concentrations to endogenous levels blocked the NO-mediated cGMP increase. These results directly demonstrate that endogenous neuronal CO production is high and indicate that while NO is the major regulator of cGMP in these neurons, CO may modulate the NO-cGMP signaling system.

Na+/H+ antiport activity conferred by Bacillus subtilis tetA(L), a 5' truncation product of tetA(L), and related plasmid genes upon Escherichia coli

An Escherichia coli transformant expressing the Bacillus subtilis tetA(L) gene from a weak promoter was challenged by growth on medium with low, increasing tetracycline concentrations. Changes in the substrate preference ratios of the TetA(L)-mediated resistances and antiports were examined in view of recent findings suggesting that TetA(L) catalyzes efflux of Na+ in exchange for protons in addition to having the ability to catalyze metal-tetracycline/H+ antiport. After growth of the transformant on 1 microgram or more of tetracycline per ml for 12 to 15 h, the tetA(L) gene in the plasmid was found to be disrupted by an IS10 element 50 bp from the 5' end of the coding sequence. This disrupted recombinant plasmid, pKB1, conferred greater tetracycline resistance and higher levels of membrane metal-tetracycline/proton antiport than the original plasmid, pJTA1, but conferred lower NA+ resistance and Na+/H+ antiport levels than the original plasmid. The results indicate that the 5' end of the gene is necessary for optimal Na+/H+ antiport but that some such activity as well as robust tetracycline/H+ antiport persists in its absence. Two plasmid genes, tet(K) and qacA, were compared with tetA(L) vis-à-vis their abilities to enhance the Na+/H+ antiporter activity of everted vesicles from E. coli transformants. tet(K), which is more closely related to tetA(L), catalyzed 22Na+ uptake by energized vesicles, whereas the less closely related qacA gene did not.

Inhibition of Nur77/Nurr1 leads to inefficient clonal deletion of self-reactive T cells

The Nur77/Nurr1 family of DNA binding proteins has been reported to be required for the signal transduction of CD3/T cell receptor (TCR)-mediated apoptosis in T cell hybridomas. To determine the role of this family of DNA-binding proteins in thymic clonal deletion, transgenic (Tg) mice bearing a dominant negative mutation were produced. The transgene consisted of a truncated Nur77 (deltaNur77) gene encoding the DNA-binding domain of Nur77 ligated to a TCR-beta enhancer resulting in early expression in thymocytes. Apoptosis of CD4+CD8+ thymocytes mediated by CD3/TCR signaling was greatly inhibited in the deltaNur77 Tg mice, compared with non-Tg littermates, after treatment with anti-CD3 or anti-TCR antibody in vivo and in vitro. Clonal deletion of self-reactive T cells was investigated in deltaNur77-Db/HY TCR-alpha/beta double Tg mice. There was a five-fold increase in the total number of thymocytes expressing self-reactive Db/HY TCR-alpha/beta in the deltaNur77-TCR-alpha/beta double Tg male mice. Deficient clonal deletion of self-reactive thymocytes was demonstrated by a 10-fold increase in the CD4+CD8+ thymocytes that expressed Tg TCR-alpha/beta. There was an eightfold increase in the CD8+, Db/HY TCR-alpha/beta T cells in the lymph nodes (LN) of delta Nur77-Db/HY TCR-alpha/beta double Tg compared with Db/HY TCR-alpha/beta Tg male mice. In spite of defective clonal deletion, the T cells expressing the Tg TCR were functionally anergic. In vivo analysis revealed increased activation and apoptosis of T cells associated with increased expression of Fas and Fas ligand in LN of deltaNur77-Db/HY TCR-alpha/beta double male mice. These results indicate that inhibition of Nur77/Nurr1 DNA binding in T cells leads to inefficient thymic clonal deletion, but T cell tolerance is maintained by Fas-dependent clonal deletion in LN and spleen.

Genetic analysis of a severe case of Dowling-Meara epidermolysis bullosa simplex

The epidermis serves an important protective function, which it manifests by producing an extensive cytoskeletal architecture, the unique feature of which are keratin filaments. Through studies that began with epidermolysis bullosa simplex (EBS) and now extend to a group of autosomal dominant human blistering skin disorders it was discovered that defects in the keratin genes lead to cell fragility and degeneration upon mechanical trauma. In most cases of EBS, point mutations occur in the keratin 5 (K5) and K14 genes expressed in the basal layer of the epidermis. The precise location of the mutation and the degree to which it causes perturbations in filament assembly correlate with disease severity. In the present study, we examine a case of EBS, which clinically lies at the severe end of the spectrum of Dowling-Meara EBS and which shows keratin filament clumping in suprabasal as well as basal cells. We show that one of the two K14 alleles has a single point substitution, giving rise to a Y129D mutation. This mutation resides 4 residues internal to the R125C/H hotspot known to account for the majority of Dowling-Meara cases. We provide functional and structural evidence to suggest why the Y129D mutation may be capable of creating such a severe form of EBS.

Chip PCR. I. Surface passivation of microfabricated silicon-glass chips for PCR

The microreaction volumes of PCR chips (a microfabricated silicon chip bonded to a piece of flat glass to form a PCR reaction chamber) create a relatively high surface to volume ratio that increases the significance of the surface chemistry in the polymerase chain reaction (PCR). We investigated several surface passivations in an attempt to identify 'PCR friendly' surfaces and used those surfaces to obtain amplifications comparable with those obtained in conventional PCR amplification systems using polyethylene tubes. Surface passivations by a silanization procedure followed by a coating of a selected protein or polynucleotide and the deposition of a nitride or oxide layer onto the silicon surface were investigated. Native silicon was found to be an inhibitor of PCR and amplification in an untreated PCR chip (i.e. native slicon) had a high failure rate. A silicon nitride (Si(3)N(4) reaction surface also resulted in consistent inhibition of PCR. Passivating the PCR chip using a silanizing agent followed by a polymer treatment resulted in good amplification. However, amplification yields were inconsistent and were not always comparable with PCR in a conventional tube. An oxidized silicon (SiO(2) surface gave consistent amplifications comparable with reactions performed in a conventional PCR tube.

Chip PCR. II. Investigation of different PCR amplification systems in microbabricated silicon-glass chips

We examined PCR in silicon dioxide-coated silicon-glass chips (12 microl in volume with a surface to volume ratio of approximately 17.5 mm(2)/microl) using two PCR reagent systems: (i) the conventional reagent system using Taq DNA polymerase; (ii) the hot-start reagent system based on a mixture of TaqStart antibody and Taq DNA polymerase. Quantitative results obtained from capillary electrophoresis for the expected amplification products showed that amplification in microchips was reproducible (between batch coefficient of variation 7.71%) and provided excellent yields. We also used the chip for PCR directly from isolated intact human lymphocytes. The amplification results were comparable with those obtained using extracted human genomic DNA. This investigation is fundamental to the integration of sample preparation, polynucleotide amplification and amplicate detection on a microchip.

Hematopoietic defects in mice lacking the sialomucin CD34

Although the pluripotent hematopoietic stem cell can only be definitively identified by its ability to reconstitute the various mature blood lineages, a diversity of cell surface antigens have also been specifically recognized on this subset of hematopoietic progenitors. One such stem cell-associated antigen is the sialomucin CD34, a highly O-glycosylated cell surface glycoprotein that has also been shown to be expressed on all vascular endothelial cells throughout murine embryogenesis as well as in the adult. The functional significance of CD34 expression on hematopoietic progenitor cells and developing blood vessels is unknown. To analyze the involvement of CD34 in hematopoiesis, we have produced both embryonic stem (ES) cells and mice that are null for the expression of this mucin. Analysis of yolk saclike hematopoietic development in embryoid bodies derived from CD34-null ES cells showed a significant delay in both erythroid and myeloid differentiation that could be reversed by transfection of the mutant ES cells with CD34 constructs expressing either a complete or truncated cytoplasmic domain. Measurements of colony-forming activity of hematopoietic progenitor cells derived from yolk sacs or fetal livers isolated from CD34-null embryos also showed a decreased number of these precursor cells. In spite of these diminished embryonic hematopoietic progenitor numbers, the CD34-null mice developed normally, and the hematopoietic profile of adult blood appeared typical. However, the colony-forming activity of hematopoietic progenitors derived from both bone marrow and spleen is significantly reduced in adult CD34-deficient animals, and these CD34-deficient progenitors also appear to be unable to expand in liquid cultures in response to hematopoietic growth factors. Even with these apparent progenitor cell deficiencies, CD34-null animals showed kinetics of erythroid, myeloid, and platelet recovery after sublethal irradiation that are indistinguishable from wild-type mice. These data strongly suggest that CD34 plays an important role in the formation of progenitor cells during both embryonic and adult hematopoiesis. However, the hematopoietic sites of adult CD34-deficient mice may still have a significant reservoir of progenitor cells that allows for normal recovery after nonmyeloablative peripheral cell depletion.

CD34+ endothelial cell lines derived from murine yolk sac induce the proliferation and differentiation of yolk sac CD34+ hematopoietic progenitors

Embryonic hematopoiesis is initiated in part in the blood islands of the yolk sac. Previous confocal microscopic analysis has shown that the CD34 antigen, a mucin-like cell surface glycoprotein that is expressed by hematopoietic progenitors and all endothelial cells of the adult and embryo, is also found on a subset of luminal hematopoietic-like cells in the yolk sac blood islands as well as on the vascular endothelium lining these early hematopoietic locations. We show here that, as in all other hematopoietic sites thus far examined, immunoaffinity-purified CD34+ nonadherent cells from murine yolk sacs contain the vast majority of erythroid and myeloid progenitor cell colony forming activity. To examine the developmental interactions between these CD34+ hematopoietic progenitor cells of the yolk sac and the CD34+ yolk sac endothelium, we have immunaffinity-purified adherent endothelial cells from day 10.5 yolk sacs using CD34 antiserum and produced cell lines by transformation with a retrovirus expressing the polyoma middle T antigen. Analysis of these cell lines for CD34, von Willebrand's factor, FLK 1 and FLT 1 expression, and capillary growth in Matrigel indicates that they appear to be endothelial cells, consistent with their original phenotype in vivo. Coculture of yolk sac CD34+ hematopoietic cells on these endothelial cell lines results in up to a 60-fold increase in total hematopoietic cell number after approximately 8 days. Analysis of these expanded hematopoietic cells showed that the majority were of the monocyte/macrophage lineage. In addition, examination of the cultures showed the rapid formation of numerous cobblestone areas, a previously described morphologic entity thought to be representative of early pluripotential stem cells. Scrutiny of the ability of these endothelial cell lines to expand committed progenitor cells showed up to a sixfold increase in erythroid and myeloid colony-forming cells after 3 to 6 days in culture, consistent with the notion that these embryonic endothelial cells mediate the expansion of these precursor cells. Polymerase chain reaction analyses showed that most of the cell lines produce FLK-2/FLT-3 ligand, stem cell factor, macrophage colony-stimulating factor, leukemia-inhibitory factor, and interleukin-6 (IL-6), whereas there is a generally low or not measurable production of granulocyte colony-stimulating factor, granulocyte-macrophage colony-stimulating factor, IL-1, IL-3, transforming growth factor beta-1, erythropoietin, or thrombopoietin. The output of mature hematopoietic cells from these cocultures can be modified to include an erythroid population by the addition of exogenous erythropoietin. These data suggest that endothelial cell lines derived form the yolk sac provide an appropriate hematopoietic environment for the expansion and differentiation of yolk sac progenitor cells into at least the myeloid and erythroid lineages.

Movement-induced depression of soleus H reflexes is consistent in humans over the range of excitatory afferents involved

The presumption that the H reflex arises exclusively from Ia afferent discharge has been challenged. If the reflex is comprised of many afferent responses, then movement-induced H reflex inhibition witnessed at one point in the recruitment curve may be quite different from the inhibition at another point in the curve. H reflex recruitment curves were constructed for three subjects during passive pedalling, isolated knee rotation and isolated hip rotation. Compared to control recruitment curves, these curves were reduced across the full spectrum of stimulus intensities. This suggests one of two possibilities: (1) all afferents contributing to the H reflex are subject to the same source and modality of inhibition; or (2) there is only one afferent type contributing to the reflex.

[Surgical treatment of gastric cardia cancer with fundoplication--a report of 193 cases]

From December 1987 to 1994, a total of 193 patients with carcinoma of the gastric cardia were surgically treated by partial esophagectomy, partial gastrectony and end-to-side esophagogastric anastomosis with fundoplication. When compared to those patients during the same time period similarly treated but with end-to-end esophagogastrostomy, the incidences of anastomotic leakage, anastomotic stricture and esophageal reflux were all significantly decreased (P < 0.01). It is a novel surgical treatment of choice for cancer of the gastric cardia.

Differential expression of human Fas mRNA species upon peripheral blood mononuclear cell activation

Human Fas/Apo-1 is a cell-surface protein that mediates apoptosis upon ligation with Fas ligand. The gene lies on the long arm of chromosome 10, consists of nine exons, and spans more than 26 kb of DNA. We previously reported the presence of a Fas variant mRNA, designated as Fas delta TM, in human peripheral blood mononuclear cells. Fas delta TM is generated by alternative splicing of the intact exon 6, which encodes the Fas transmembrane domain. In the present study, we describe three novel forms of Fas mRNA that are generated by alternative splicing of exons 3, 4, 6 and 7. These three mRNA variants undergo a frameshift and produce truncated polypeptides because of the appearance of a stop codon in the altered open reading frame. On activation of the peripheral blood mononuclear cells, a decreased expression of alternatively spliced Fas mRNA species correlated with increased cell-surface expression of Fas. These results suggest that differential expression of alternatively spliced Fas mRNAs may play a role in regulation of Fas function via regulation of the production of the membrane-bound and the soluble, secreted Fas protein products.

Inflammatory pseudocyst associated with trisomy 21 and Hirschsprung's disease

A 15-month-old black male with trisomy 21 and Hirschsprung's disease developed an inflammatory abdominal pseudocyst 1 month after Swenson pull-through repair. Although abdominal pseudocyst associated with ventriculoperitoneal shunts, peritoneal dialysis catheters, meconium peritonitis, and pancreatitis have been reported, this is the first report of a pseudocyst developing 1 month after a surgical repair of Hirschsprung's disease.

Primary leiomyosarcoma of the maxilla with regional lymph node metastasis. Report of a case and review of the literature

A rare case of oral leiomyosarcoma diagnosed with the aid of immunohistochemical and electron microscopic examinations together with a review of the literature are reported. The patient was a 70-year-old Japanese man. The primary tumor involved the maxillary gingiva and bone and metastasized to the cervical lymph nodes. On histologic examination the tumor showed invasive growth into the maxillary bone. It was composed of interlacing fascicles of spindle-shaped cells with eosinophilic cytoplasm and elongated, blunt-ended nuclei. The tumor formed extensive metastatic foci in the cervical lymph nodes. On immunohistochemical examination most of the tumor cells were positive for desmin, smooth muscle-specific actin, and myosin. The ultrastructural characteristics of the tumor cells were abundant microfilaments, pinocytotic vesicles, and basement membrane formation. The findings were indicative of a tumor demonstrating myogenic differentiation. A review of the literature during the past 50 years disclosed a total of 60 oral leiomyosarcomas, including our case.

The effect of levonorgestrel-releasing intrauterine device (20 micrograms/day) (LNG-IUD-20) on the morphological structure of human endometrium: a study of the endometrial factor VIII activity in the women before and after insertion of LNG-IUD-20 by the digital image analysis

The specimens of endometria were obtained from 18 women using an intrauterine device releasing levonorgestrel at 20 micrograms/day (LNG-IUD-20). An immunoperoxidase reaction, PAP method, with the antiserum of Factor VIII as the primary antibody, was carried out in the endometrial biopsies to detect the Factor VIII activity in the endometrial endothelium before and after insertion of LNG-IUD-20. The immunoperoxidase activity was quantitatively assessed by a computer digital image analyser. The results revealed that there were a lower Factor VIII activity in the endometrial endothelial cells after insertion of LNG-IUD-20 (p < 0.001) when compared with the control. From the results of the present study, it is suggested that the synthesis and release of endometrial endothelial Factor VIII might be inhibited by the insertion of LNG-IUD20.

Demonstration of kappa 3-opioid receptors in the SH-SY5Y human neuroblastoma cell line

In addition to the mu- and delta-opioid receptors previously reported, the SH-SY5Y human neuroblastoma cell line has high levels of kappa 3 receptors, accounting for 40% of total opioid binding, as measured with [3H]-diprenorphine binding. Competition studies reveal binding profiles for all three receptor classes that are similar to those observed in brain membranes. Differentiation with retinoic acid increases the levels of opioid receptor binding in the cell line, with the largest elevations in kappa 3 binding. Fully 75% of the increased binding corresponds to kappa 3 sites, which represent 50% of total opioid receptor binding in differentiated cells. Morphine inhibits forskolin-stimulated cyclic AMP accumulation, and this effect is readily blocked by the mu antagonist D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP). Naloxone benzoylhydrazone, a kappa 3 agonist, inhibits forskolin-stimulated cyclic AMP accumulation more potently than morphine and is not reversed by CTAP. These studies indicate that SH-SY5Y cells contain high levels of functional kappa 3 receptors.

Biosynthesis of basement membrane molecules by salivary adenoid cystic carcinoma cells: an immunofluorescence and confocal microscopic study

The biosynthesis of basement membrane molecules and fibronectin was studied in vitro in the two different human cell systems (ACC2 and ACC3) established from adenoid cystic carcinomas (ACC) of the salivary gland using immunofluorescence and confocal microscopy. When cells were attached and spread on dishes, fine granular immunofluorescence for type IV collagen, laminin, heparan sulphate proteoglycan, entactin, and fibronectin first appeared diffusely in the cytoplasm, and then changed in aggregation of coarse granules in the perinuclear area. With formation of colonies, these signals were present in the extracellular space, initially in the basal aspect of attached cells and consequently in the lateral intercellular space. After the cells formed a confluent monolayer, extracellular signals started to decrease in inverse proportion to the reappearance of intracellular ones. The results indicate that the parenchymal cells of ACC synthesize these five extracellular matrix molecules, secrete them into the extracellular milieu and remodel the extracellular deposits. It is suggested that the characteristic stromal architecture of ACC, represented by stromal pseudocysts, results from their own secretion of the basement membrane molecules and fibronectin.

The basal keratin network of stratified squamous epithelia: defining K15 function in the absence of K14

Keratin 5 and keratin 14 have been touted as the hallmarks of the basal keratin networks of all stratified squamous epithelia. Absence of K14 gives rise to epidermolysis bullosa simplex, a human blistering skin disorder involving cytolysis in the basal layer of epidermis. To address the puzzling question of why this disease is primarily manifested in skin rather than other stratified squamous epithelia, we ablated the K14 gene in mice and examined various tissues expressing this gene. We show that a key factor is the presence of another keratin, K15, which was hitherto unappreciated as a basal cell component. We show that the levels of K15 relative to K14 vary dramatically among stratified squamous epithelial tissues, and with neonatal development. In the absence of K14, K15 makes a bona fide, but ultrastructurally distinct, keratin filament network with K5. In the epidermis of neonatal mutant mice, K15 levels are low and do not compensate for the loss of K14. In contrast, the esophagus is unaffected in the neonatal mutant mice, but does appear to be fragile in the adult. Parallel to this phenomenon is that esophageal K14 is expressed at extremely low levels in the neonate, but rises in postnatal development. Finally, despite previous conclusions that the formation of suprabasal keratin filaments might depend upon K5/K14, we find that a wide variety of suprabasal networks composed of different keratins can form in the absence of K14 in the basal layer.

Immune responses to nucleic acid vaccines to rabies virus

A plasmid vector expressing the full-length rabies virus glycoprotein (G protein) under the control of the simian virus 40 (SV40) promoter has previously been shown to induce upon intramuscular (i.m.) inoculation into mice a specific B- and T-cell-mediated immune response and protection against challenge with a virulent strain of the virus. Here we tested two parameters that might affect the efficacy of this DNA vaccine. First, we replaced the SV40 promoter of the original vector with the early promoter derived from cytomegalovirus leaving all other parameters of the plasmid intact. Although upon transfection in vitro the two vectors showed a striking difference in their ability to cause stable expression of the rabies virus G protein, upon i.m. inoculation into mice both constructs induced comparable immune responses. Second, we constructed a vector that induces expression of a secreted form of rabies G protein by inserting a stop codon just upstream of the transmembrane domain of the rabies G protein gene. The immune responses to the DNA vaccines expressing the two different forms of the G protein, secreted and membrane bound, were compared and found to be similar in magnitude. The long-term effect of DNA vaccination was also investigated especially with regard to adverse immunological reactions such as the induction of unresponsiveness against rabies virus and the development of antibodies to DNA. DNA vaccination was found to induce long-lasting immunity to rabies virus without apparent negative side effects such as development of T cell tolerance or generation of anti-DNA antibodies.

Rapid optimization of electroporation conditions for plant cells, protoplasts, and pollen

The optimization of electroporation conditions for maximal uptake of DNA during direct gene transfer experiments is critical to achieve high levels of gene expression in transformed plant cells. Two stains, trypan blue and fluorescein diacetate, have been applied to optimize electroporation conditions for three plant cell types, using different square wave and exponential wave electroporation devices. The different cell types included protoplasts from tobacco, a stable mixotrophic suspension cell culture from soybean with intact cell walls, and germinating pollen from alfalfa and tobacco. Successful electroporation of each of these cell types was obtained, even in the presence of an intact cell wall when conditions were optimized for the electroporation pulse. The optimal field strength for each of these cells differs, protoplasts having the lowest optimal pulse field strength, followed by suspension cells and finally germinating pollen requiring the strongest electroporation pulse. A rapid procedure is described for optimizing electroporation parameters using different types of cells from different plant sources.

Cloning and functional characterization through antisense mapping of a kappa 3-related opioid receptor

We have identified a putative opioid receptor from mouse brain (KOR-3), belonging to the G protein-coupled receptor family, that is distinct from the previously cloned mu, delta, and kappa 1 receptors. Assignment of the clone to the opioid receptor family derives from both structural and functional studies. Its predicted amino acid sequence is highly homologous to that of the other opioid receptors, particularly in many of the transmembrane regions, where long stretches are identical to mu, delta, and kappa 1 receptors. Both cyclazocine and nalorphine inhibit cAMP accumulation in COS-7 cells stably expressing the clone. Northern analysis shows that the mRNA is present in brain but not in a number of other organs. Southern analysis suggests a single gene encoding the receptor. A highly selective monoclonal antibody directed against the native kappa 3 receptor recognizes, in Western analysis, the clone expressed in COS-7 cells. The in vitro translation product is also labeled by the antibody. Additional clones reveal the presence of several introns, including one in the second extracellular loop and another in the first transmembrane region. Antisense studies with an oligodeoxynucleotide directed against a region of the second extracellular loop reveal a selective blockade of kappa 3 analgesia in vivo that is not observed with a mismatch oligodeoxynucleotide based upon the antisense sequence. The mu, delta, and kappa 1 analgesia is unaffected by this antisense treatment. Antisense mapping of the clone downstream from the splice site in the first transmembrane region reveals that six different antisense oligodeoxynucleotides all block kappa 3 analgesia. In contrast, only one of an additional six different antisense oligodeoxynucleotides directed at regions upstream from this splice site is effective. This strong demarcation between the two regions raises the possibility of splice variants of the receptor. An additional clone reveals an insert in the 3' untranslated region. In conclusion, the antibody and antisense studies strongly associate KOR-3 with the kappa 3-opioid receptor, although it is not clear whether it is the kappa 3 receptor itself or a splice variant.