Lysophosphatidic acid LPA1 and LPA3 receptors play roles in the maintenance of late tissue plasminogen activator-induced central poststroke pain in mice

We developed a mouse model for central post-stroke pain (CPSP), a centrally-originated neuropathic pain (NeuP). In this mode, mice were first injected with Rose Bengal, followed by photo-irradiation of left middle cerebral artery (MCA) to generate thrombosis. Although the MCA thrombosis was soon dissolved, the reduced blood flow remained for more than 24 h due to subsequent occlusion of microvessels. This photochemically induced thrombosis (PIT) model showed a hypersensitivity to the electrical stimulation of both sides of paw, but did not show any abnormal pain in popular thermal or mechanical nociception tests. When tissue-type plasminogen activator (tPA) was injected 6 h after the PIT stress, tPA-dependent hypersensitivity to the electrical paw stimulation and stable thermal and mechanical hyperalgesia on both sides for more than 17 or 18 days after the PIT treatment. These hyperalgesic effects were abolished in lysophosphatidic acid receptor 1 (LPA1)- and lysophosphatidic acid receptor 3 (LPA3)-deficient mice. When Ki-16425, an LPA1 and LPA3 antagonist was treated twice daily for 6 days consecutively, the thermal and mechanical hyperalgesia at day 17 and 18 were significantly reversed. The liquid chromatography-mass spectrometry (LC-MS/MS) analysis revealed that there is a significant increase in several species of LPA molecules in somatosensory S-I and medial dorsal thalamus (MD), but not in striatum or ventroposterior thalamus. All these results suggest that LPA1 and LPA3 signaling play key roles in the development and maintenance of CPSP.

Ecto-F0/F1 ATPase as a novel candidate of prothymosin α receptor

OBJECTIVES

Prothymosin α (ProTα) was reported to inhibit the neuronal necrosis by facilitating the plasma membrane localization of endocytosed glucose transporter 1/4 through an activation of putative G_i-coupled receptor. The present study aims to identify a novel ProTα target, which may lead to an activation of G_i-coupled receptor.

METHODS

We used G_i-rich lipid rafts fraction of retinal cell line N18-RE-105 cells for affinity cross-linking. The biological confirmation that F₀/F₁ ATPase is a target protein complex was performed by cell-free experiments using ELISA-based binding assay, surface plasmon resonance assay and quartz crystal microbalance assay, and cell-based experiments to measure extracellular ATP level in the HUVECs culture.

RESULTS

From the cross-linking study and above-mentioned protein-protein interaction assays, ATP5A1 and ATP5B, F₁ ATPase subunits were found to ProTα binding target proteins. In the culture of HUVEC cells, furthermore, ProTα increased the extracellular ATP levels in a reversible manner by anti-ATP5A1- and ATP5B-antibodies.

CONCLUSION

The present study suggests that ProTα may activate ecto-F₀/F₁ ATPase and produced ATP. This study leads to next subjects whether produced ATP and its metabolites, ADP or adenosine may activate corresponding G_i-coupled receptors.

Clinical significance of heparin-binding epidermal growth factor-like growth factor in peritoneal fluid of ovarian cancer

Epidermal growth factor receptor (EGFR) has been implicated in tumour growth and extension of ovarian cancer. Peritoneal fluid in ovarian cancer patients contains various growth factors that can promote tumour growth and extension. In order to investigate the clinical significance of EGFR ligands as activating factors of ovarian cancer, we examined the cell proliferation-promoting activity and the level of EGFR ligands in peritoneal fluid obtained from 99 patients. Proliferation-promoting activity in peritoneal fluid from 63 ovarian cancer patients (OVCA) was much higher than peritoneal fluid from 18 ovarian cyst patients (OVC) and 18 normal ovary patients (NO), and the activity was suppressed only by antibodies against EGFR or heparin-binding epidermal growth factor (HB-EGF). A large difference was observed in the level of EGFR ligands between HB-EGF and TGF-α or amphiregulin. The concentration of HB-EGF in OVCA significantly increased compared to that in OVC or NO (P<0.01). No significant difference in the concentration of TGF-α and amphiregulin was found between the OVCA and NO or OVC groups. In peritoneal fluid, HB-EGF is sufficiently elevated to activate cancer cells even at an early stage of OVCA. These results suggested that HB-EGF in peritoneal fluid might play a key role in cell survival and in the proliferation of OVCA.

Atropine prevents midazolam-induced core hypothermia in elderly patients

STUDY OBJECTIVE

To test the hypothesis that core temperature is well preserved when atropine and midazolam are combined.

DESIGN

Randomized, blinded study.

SETTING

Department of Anesthesia, Yamanashi Medical University.

PATIENTS

40 elderly, ASA physical status I and II patients (aged more than 60 years).

INTERVENTIONS

Patients were randomly assigned (n = 10 per group) to premedication with: 1) saline control; 2) midazolam 0.05 mg/kg; 3) atropine 0.01 mg/kg; and 4) midazolam 0.05 mg/kg combined with atropine 0.01 mg/kg. All premedication was given on the ward at approximately 8:30 am, approximately 30 minutes before induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

Core temperatures were measured at the right tympanic membrane. Mean skin temperature was calculated as 0.3 x (T(chest) + T(arm)) + 0.2 x (T(thigh) + T(calf)). Fingertip perfusion was evaluated using forearm minus fingertip and calf minus toe, skin-surface temperature gradients. Temperatures were evaluated at the time of premedication and 30 minutes later, just before induction of anesthesia. Core temperature remained nearly constant in the control patients (0.1 +/- 0.2 degrees C; mean +/- SD), whereas it decreased significantly in the patients given midazolam alone (-0.3 +/- 0.1 degrees C). Atropine alone increased core temperature (0.3 +/- 0.2 degrees C), although the increase was not statistically significant. The combination of midazolam and atropine attenuated the hypothermia induced by midazolam alone (0.0 +/- 0.2 degrees C). Initial skin-temperature gradients exceeded 0 degrees C in all groups, indicating that the patients were vasoconstricted. The gradients were unchanged by premedication with saline or atropine. Midazolam significantly decreased the gradient (-1.8 +/- 1.1 degrees C), as did the combination of midazolam and atropine (-1.4 +/- 0.9 degrees C).

CONCLUSIONS

The thermoregulatory effects of benzodiazepine receptor agonist and cholinergic inhibitors oppose each other, and the combination leaves core temperature unchanged.

Identification of serum factor inducing ectodomain shedding of proHB-EGF and sStudies of noncleavable mutants of proHB-EGF

The ectodomain of the transmembrane form of HB-EGF (proHB-EGF) is cleaved at the cell surface by proteases, yielding a soluble growth factor. A number of stimuli, including TPA, accelerate this cleavage. However, proHB-EGF is shed constitutively under normal culture conditions without any particular stimuli. We demonstrate here that constitutive cleavage resulted largely from factor(s) contained in supplemented FCS in a culture medium. Analysis of serum factors, including digestion with enzymes, separation by thin layer chromatography, and shedding assay with purified phospholipids, revealed that lysophosphatidic acid (LPA) is a major factor in FCS for stimulation of proHB-EGF shedding. We also studied here ectodomain shedding of two kinds of mutant form of proHB-EGF which have a single amino acid substitution around the putative cleavage sites. These mutant forms showed resistance to stimuli of both TPA and LPA, suggesting that proHB-EGF is cleaved at the similar site by stimulation with TPA and LPA.

Immunohistochemical distribution of CD9, heparin binding epidermal growth factor-like growth factor, and integrin alpha3beta1 in normal human tissues

The tetra-membrane-spanning protein CD9 forms a complex with a membrane-anchored heparin binding epidermal growth factor-like growth factor (HB-EGF) and integrin alpha3beta1 in some human and monkey cell lines. We show here the immunohistochemical distribution of CD9, HB-EGF, and integrin alpha3beta1 in normal human tissues. Distribution of CD9, HB-EGF, and integrin alpha3beta1 was similar in various tissues, including transitional epithelium, squamous epithelium, thyroid follicular epithelium, adrenal cortex, testis, smooth muscle, and stromal fibrous tissue. However, distribution of the three proteins did not coincide in some tissues, such as lung, liver, kidney, gastric and intestinal epithelium, pancreas, salivary gland, and ovary. In striated muscle, including cardiac muscle, CD9 was present not in the muscle cells themselves but in the endomysium and perimysium, whereas HB-EGF was distributed in the muscle cells themselves. CD9 was distributed in the myelin, but HB-EGF was found in the axon of the peripheral and central nervous systems. Coincident distribution of integrin alpha3beta1 with others was not observed in muscles and neural tissues. In conclusion, there is a possibility of complex formation and functional cooperation of CD9 with HB-EGF and/or integrin alpha3beta1 in several tissues.

Involvement of deregulated epiregulin expression in tumorigenesis in vivo through activated Ki-Ras signaling pathway in human colon cancer cells

To identify the genes located downstream of the activated Ki-Ras signaling pathways in human colon cancer cells, a PCR-based cDNA subtraction library was constructed between HCT116 cells and HCT116-derived activated Ki-ras-disrupted cells (HKe3). One of the genes in HCT116 that was evidently up-regulated was epiregulin, a member of the epidermal growth factor family that is expressed in many kinds of human cancer cells. HKe3-stable transfectants expressing activated Ki-Ras regained over-expression of epiregulin. To further elucidate the biochemical structure and significance of epiregulin expression in tumorigenesis, HKe3-stable transfectants expressing epiregulin (e3-pSE cells) were established. Epiregulin existed as highly glycosylated membrane-bound forms, and TPA rapidly induced ectodomain shedding of epiregulin. Furthermore, the conditioned medium of e3-pSE cells showed more DNA synthesis for 32D cells expressing epidermal growth factor receptor (DER) cells than that of HKe3. Although anchorage-independent growth in soft agar was not observed for e3-pSE cells, tumorigenicity in nude mice was observed evidently, and their growth rate was correlated with each amount of exogenous epiregulin expression. These results suggested that activated Ki-Ras will be one of the factors contributing to the overexpression of epiregulin in human colon cancer cells, and that epiregulin will play a critical role in human tumorigenesis in vivo.

Heparin-binding EGF-like growth factor: a juxtacrine growth factor

Heparin-binding EGF-like growth factor (HB-EGF), which belongs to the EGF-family growth factors, is synthesized as a membrane-anchored form (proHB-EGF). Proteolytic cleavage of proHB-EGF at the extracellular domain yields the soluble form of HB-EGF (sHB-EGF). ProHB-EGF is not only the precursor molecule for sHB-EGF but also a biologically active molecule itself. Recent studies indicate that proHB-EGF has unique properties distinct from the soluble form. ProHB-EGF forms a complex with membrane proteins including a tetramembrane spanning protein: CD9, an adhesion molecule integrin: alpha3beta1, and heparan sulfate proteoglycans. The complex is localized at the cell-cell contact site, suggesting that proHB-EGF may function in cell-to-cell signaling by a juxtacrine mechanism. In an in vitro model system, proHB-EGF showed growth inhibitory activity, while sHB-EGF was growth stimulatory. Ectodomain shedding, conversion of the membrane-anchored form into the soluble form, is regulated by multiple signaling pathways. All these characteristics imply that proHB-EGF and sHB-EGF are used in different ways. In vivo functions of sHB-EGF and proHB-EGF have been largely undefined, but recent studies implicate them in a variety of physiological processes including blastocyst implantation and wound healing.

Identification of mammalian TOM22 as a subunit of the preprotein translocase of the mitochondrial outer membrane

A mitochondrial outer membrane protein of approximately 22 kDa (1C9-2) was purified from Vero cells assessing immunoreactivity with a monoclonal antibody, and the cDNA was cloned based on the partial amino acid sequence of the trypsin-digested fragments. 1C9-2 had 19-20% sequence identity to fungal Tom22, a component of the preprotein translocase of the outer membrane (the TOM complex) with receptor and organizer functions. Despite such a low sequence identity, both shared a remarkable structural similarity in the hydrophobicity profile, membrane topology in the Ncyt-Cin orientation through a transmembrane domain in the middle of the molecule, and the abundant acidic amino acid residues in the N-terminal domain. The antibodies against 1C9-2 inhibited the import of a matrix-targeted preprotein into isolated mitochondria. Blue native polyacrylamide gel electrophoresis of digitonin-solubilized outer membranes revealed that 1C9-2 is firmly associated with TOM40 in the approximately 400-kDa complex, with a size and composition similar to those of the fungal TOM core complex. Furthermore, 1C9-2 complemented the defects of growth and mitochondrial protein import in Deltatom22 yeast cells. Taken together, these results demonstrate that 1C9-2 is a functional homologue of fungal Tom22 and functions as a component of the TOM complex.

Contact-dependent growth inhibition and apoptosis of epidermal growth factor (EGF) receptor-expressing cells by the membrane-anchored form of heparin-binding EGF-like growth factor

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) transduces mitogenic signals through the EGF receptor (EGFR). There are two forms of HB-EGF, the membrane-anchored form (pro-HB-EGF) and the soluble form (sHB-EGF). We studied the biological activity of pro-HB-EGF by using a model in which pro-HB-EGF-expressing effector cells was co-cultured with EGFR-expressing target cells. The DER cell, an EGFR-expressing derivative of the interleukin-3-dependent hematopoietic 32D cell line, grows well in the presence of EGF or sHB-EGF without IL-3. When DER cells were co-cultured on a monolayer of Vero-H cells overexpressing pro-HB-EGF, growth inhibition and subsequent apoptosis were induced in the DER cells even in the presence of excess amounts of EGF or sHB-EGF. Such growth inhibition of DER cells was abrogated when specific antagonists for pro-HB-EGF were added in the culture medium or when direct contact of DER cells with Vero-H cells was prevented, indicating that pro-HB-EGF is involved in this inhibitory effect. Pro-HB-EGF-induced apoptosis of DER cells was also observed even in the presence of IL-3. This rules out the possibility of simple competition between soluble EGFR ligands and pro-HB-EGF. Moreover, 32D cells expressing EGFR mutant composed of the extracellular and the transmembrane domain of EGFR and the cytoplasmic domain of erythropoietin receptor did not undergo apoptosis by co-culture with Vero-H cells, indicating that the inhibitory signal induced by pro-HB-EGF-expressing Vero-H cells is mediated to DER cells via EGFR and that the cytoplasmic domain of EGFR is essential for pro-HB-EGF-induced apoptosis. From these results, we concluded that pro-HB-EGF has unique biological activity through cell-cell contact that is distinct from the activity of sHB-EGF.

Purification and characterization of D-glucosaminitol dehydrogenase from Agrobacterium radiobacter

D-Glucosaminitol dehydrogenase, which catalyzes the conversion of D-glucosaminitol to 3-keto-D-glucosaminitol, was purified to apparent homogeneity from extracts of Agrobacterium radiobacter. This organism has constitutively depressed levels of the enzyme but expression of the enzyme is induced by addition of D-glucosamine to the medium. Purification included ammonium sulfate fractionation and chromatography on columns of DEAE-Sephacel, Octyl-Sepharose CL-4B, and Cellulofine. The purified enzyme migrated as a single band, coinciding with dehydrogenase activities specific for D-glucosaminitol and ethanol, when electrophoresed on a 7.5% polyacrylamide gel at pH 8.0. Electrophoresis on a 12.5% PAGE in the presence of 1% SDS also yielded a single band. The enzyme had an apparent molecular mass of 79 kDa, as measured by the pattern of elution from a column of Cellulofine. The results indicated that the enzyme was a dimer of identical (or nearly identical) subunits of 39.5 kDa. D-Glucosaminitol dehydrogenase required NAD+ as a cofactor and used ethanol as the preferred substrate, as well as aliphatic alcohols with 2 to 4 carbon atoms, D-glucosaminitol, D-glucosaminate, DL-allothreonine, glycerol, and erythritol as additional substrates. In 50 mM Tris-HCl buffer (pH 9.0) at 25 degrees C, the K(m) for D-glucosaminitol, ethanol, and NAD+ were 2.2, 2.0, and 0.08 mM, respectively. The enzyme had a pH optimum of 10 for D-glucosaminitol and 8.5 for ethanol. The enzyme lost substantial activity when treated with pyrazole, with certain reagents that react with sulfhydryl groups and with Zn2+ ion. The various results together suggest that the enzyme exploits different amino acid residues for the dehydrogenation of ethanol and of D-glucosaminitol.

A metalloprotease-disintegrin, MDC9/meltrin-gamma/ADAM9 and PKCdelta are involved in TPA-induced ectodomain shedding of membrane-anchored heparin-binding EGF-like growth factor

The ectodomains of many proteins located at the cell surface are shed upon cell stimulation. One such protein is the heparin-binding EGF-like growth factor (HB-EGF) that exists in a membrane-anchored form which is converted to a soluble form upon cell stimulation with TPA, an activator of protein kinase C (PKC). We show that PKCdelta binds in vivo and in vitro to the cytoplasmic domain of MDC9/meltrin-gamma/ADAM9, a member of the metalloprotease-disintegrin family. Furthermore, the presence of constitutively active PKCdelta or MDC9 results in the shedding of the ectodomain of proHB-EGF, whereas MDC9 mutants lacking the metalloprotease domain, as well as kinase-negative PKCdelta, suppress the TPA-induced shedding of the ectodomain. These results suggest that MDC9 and PKCdelta are involved in the stimulus-coupled shedding of the proHB-EGF ectodomain.

Enhancement of DNA-transfection frequency by X-rays

This study was conducted to evaluate the frequency of DNA transfection into human cells following X-ray irradiation. We transfected plasmid DNA (pSV2neo) into human cells, HeLa and PA-1, by either calcium phosphate precipitation or the lipofection method immediately after irradiating the cells with various doses of X-rays. The transfection frequency was evaluated by counting the number of G418-resistant colonies. When circular plasmid DNA was used, irradiation up to a dose of 2 Gy dose-dependently increased the transfection frequency, which reached a maximum of 5 to 10-fold that of the control unirradiated cells. When linear plasmid DNA was used, the transfection frequency was 2 times higher than that of circular DNA. All five of the clones that were randomly chosen expressed the transfected neo gene. In addition, the pSV2neo gene was randomly integrated into the genomic DNA of each clone. These findings indicate that X-ray treatment can facilitate foreign DNA transfer into human cells and that radiation-induced DNA breaks may promote the insertion of foreign DNA into host DNA. The enhancement of DNA transfection with X-rays may be instrumental in practicing gene therapy.

Expression and distribution of CD9 in myelin of the central and peripheral nervous systems

CD9 is a member of the newly identified tetra-membrane-spanning protein family. We show here that CD9 is a constituent of myelin in the central and peripheral nervous systems. Expression of CD9 was detected in human cerebral white matter and sciatic nerve by Northern and Western blotting. Myelin in the central and peripheral nervous systems was strongly stained with a monoclonal antibody against human CD9 antigen in paraffin-embedded sections. CD9 was detected in adult nervous tissue but not in developing brain at less than 20 weeks of gestation. Immunohistochemical studies indicated that expression of CD9 is correlated with myelination and is somewhat delayed compared with expression of myelin basic protein, a major component protein of myelin. In the central nervous system, CD9 was detected along the outermost membrane of compact myelin but not inside compact myelin or the periaxonal region. Although the membrane-anchored form of heparin-binding epidermal-growth-factor-like growth factor (proHB-EGF), which is identical to the diphtheria toxin receptor, forms a complex with CD9 in some human and monkey cell lines, proHB-EGF was not detected in myelin immunocytochemically. The distribution of CD9 in the outer surface of myelin and its relatively late developmental appearance suggest that CD9 may interact with the extracellular matrix or cell adhesion molecules and participate in the maintenance of the entire myelin sheath.

Membrane-anchored heparin-binding EGF-like growth factor (HB-EGF) and diphtheria toxin receptor-associated protein (DRAP27)/CD9 form a complex with integrin alpha 3 beta 1 at cell-cell contact sites

Heparin-binding epidermal growth factor-like growth factor (HB-EGF) is a member of the EGF family of growth factors, which interact with EGF receptor to exert mitogenic activity. The membrane-anchored form of HB-EGF, proHB-EGF, is biologically active, providing mitogenic stimulation to neighboring cells in a juxtacrine mode. ProHB-EGF forms a complex with diphtheria toxin receptor-associated protein (DRAP27)/CD9, a tetra membrane-spanning protein that upregulates the juxtacrine mitogenic activity of proHB-EGF. We explored whether other proteins associate with DRAP27/CD9 and proHB-EGF. Immunoprecipitation with anti-DRAP27/CD9 resulted in preferential coprecipitation of integrin alpha 3 beta 1 from Vero cell, A431 cell and MG63 cell lysates. Anti-integrin alpha 3 or anti-integrin beta 1 coprecipitated DRAP27/CD9 from the same cell lysates. Chemical cross-linking confirmed the physical association of DRAP27/CD9 and integrin alpha 3 beta 1. Using Vero-H cells, which overexpress HB-EGF, we also demonstrated the association of proHB-EGF with DRAP27/CD9 and integrin alpha 3 beta 1. Moreover, colocalization of proHB-EGF, DRAP27/CD9, and integrin alpha 3 beta 1 at cell-cell contact sites was observed by double-immunofluorescence staining. At cell-cell contact sites, DRAP27/CD9 was highly coincident with alpha-catenin and vinculin, suggesting that DRAP27/CD9, proHB-EGF, and integrin alpha 3 beta 1 are colocalized with adherence junction-locating proteins. These results indicate that direct interaction of growth factors and cell adhesion molecules may control cell proliferation during the cell-cell adhesion process.

D-glucosaminate aldolase activity of D-glucosaminate dehydratase from Pseudomonas fluorescens and its requirement for Mn2+ ion

When D-glucosaminate dehydratase (GADH) was incubated with D-glucosaminate (GlcNA) in veronal buffer (VB; 0.01 M, pH 8.0), GlcNA was converted stoichiometrically to glyceraldehyde, pyruvate, and ammonia (aldolase reaction A). This reaction occurred in addition to the dehydratase reaction (conversion of GlcNA to 2-keto-3-deoxy-D-gluconate and ammonia: alpha,beta-elimination reaction, B). The ratio of the activities (A:B) was about 1:4. However, in potassium phosphate buffer (KPB; 0.04 M, pH 8.0), the aldolase reaction was inhibited to 3-4% of that in VB, and also inhibited by various derivatives of glycerol, in particular, glycerol-3-phosphate (glycerol-3-P) and glyceraldehyde-3-phosphate (glyceraldehyde-3-P) in VB. The native enzyme was inhibited by incubation with 0.1 M EDTA, and the activity was restored by incubation of the EDTA-treated enzyme with (Mn2+ + pyridoxal 5'-phosphate (PLP)). When the EDTA-treated enzyme was incubated with (Mn2+ + PLP + glycerol-3-P), the activity of reaction B increased to 131% but that of reaction A decreased to 21%. These results suggested that Mn2+, PLP, and the phosphate group of glycerol-3-P are involved in formation of the active enzyme. In the case of the aldolase reaction, Mn2+ ion, which might be essential for the reaction, is chelated by the phosphate group of glycerol-3-P with resultant inhibition of the aldolase reaction.

The membrane protein CD9/DRAP 27 potentiates the juxtacrine growth factor activity of the membrane-anchored heparin-binding EGF-like growth factor

The membrane-anchored heparin-binding EGF-like growth factor precursor (proHB-EGF)/diphtheria toxin receptor (DTR) belongs to a class of transmembrane growth factors and physically associates with CD9/DRAP27 which is also a transmembrane protein. To evaluate the biological activities of proHB-EGF/DTR as a juxtacrine growth factor and the biological significance of its association with CD9/DRAP27, the mitogenic activity of proHB-EGF/DTR was analyzed using stable transfectants of mouse L cells expressing both human proHB-EGF/DTR and monkey CD9/DRAP27, or either one alone. Juxtacrine activity was assayed by measuring the ability of cells in co-culture to stimulate DNA synthesis in an EGF receptor ligand dependent cell line, EP170.7. LH-2 cells expressing human proHB-EGF/DTR stimulated EP170.7 cell growth moderately. However, LCH-1 cells, a stable co-transfectant expressing both human proHB-EGF/DTR and monkey CD9/DRAP27 cDNAs, dramatically unregulated the juxtacrine growth factor activity of proHB-EGF/DTR approximately 25 times over that of LH-2 cells even though both cell types expressed similar levels of proHB-EGF/DTR on the cell surface. Anti-CD9/DRAP27 antibodies which were not able to neutralize the mitogenic activity of soluble HB-EGF suppressed LCH-1 cell juxtacrine growth activity to the same extent as did anti-HB-EGF neutralizing antibodies and CRM 197, specific inhibitors of human HG-EGF. These findings suggest that optimal expression of the juxtacrine growth activity of proHB-EGF/DTR requires co-expression of CD9/DRAP27. These studies also indicate that growth factor potentiation effects which have been observed previously for soluble growth factors also occurs at the level of cell surface associated growth factors.

Oral pilocarpine for radiation-induced xerostomia: integrated efficacy and safety results from two prospective randomized clinical trials

PURPOSE

Pilocarpine hydrochloride administered in either a fixed-dose or in a dose-titration protocol three times a day for 12 weeks was evaluated for its ability to relieve symptoms of postradiation xerostomia and to improve saliva production. The studies were randomized, double-blind, placebo-controlled, multicenter clinical trials. A total of 369 patients who had received at least 40 Gy of radiation to the head and neck with clinically significant xerostomia were enrolled in the two studies. In the dose-titration study, 162 patients were enrolled and they received a thrice daily regimen of 2.5 mg tablets for first 4 weeks, 5.0 mg tablets for the second 4 weeks, and 10.0 mg tablets for last 4 weeks of a 12-week study. Patients in the titration study were allowed to down titrate following at least one dose escalation to alleviate bothersome side effects, if any. In the fixed dose study, 207 patients received either placebo, 5.0 mg, or 10.0 mg tablets t.i.d. for 12 weeks.

METHODS AND MATERIALS

Patients were evaluated for symptomatic relief by responding to questionnaires using visual analog scales and categorical questions; and, for saliva production by sialometry. Questionnaires measured relief of intraoral dryness, improvement in overall condition (global response), oral discomfort, difficulty in speaking, chewing and swallowing, denture wearing, and usage of artificial saliva. Evaluations were conducted at baseline, and weeks 4, 8, and 12.

RESULTS

There were statistically significant improvements in salivary flow in pilocarpine treatment groups vs. placebo. There was a significant improvement in the overall "global" condition of xerostomia associated with the use of pilocarpine in both studies. In the fixed-dose study, there were significant improvements in oral dryness, mouth comfort, ability to speak, and reduction in the use of oral comfort agents. The dose-titration study showed improvements in dryness that approached significance (p = 0.057) and a decreased use of oral comfort agents (p = 0.045). All pilocarpine dosages (2.5, 5.0, and 10.0 mg three times a day) were judged to be safe. Adverse experiences were those expected for a cholinergic agonist, with the most common being mild to moderate sweating. The incidence of these events increased by dose.

CONCLUSION

It is concluded that in these studies pilocarpine produced clinically significant benefits with acceptable side effects and risks for the treatment of symptomatic postradiation xerostomia. The incidence of most adverse events increased with dose. Best results may require continuous treatment for more than 8 weeks with doses greater than 2.5 mg three times a day. A 5.0 mg thrice daily regimen produced the best clinical results when both efficacy and side effects were taken into consideration. There may be some patients who would experience some additional benefit by increasing the dose to 10 mg thrice daily.

Heparin-binding EGF-like growth factor, which acts as the diphtheria toxin receptor, forms a complex with membrane protein DRAP27/CD9, which up-regulates functional receptors and diphtheria toxin sensitivity

DRAP27, the monkey homolog of human CD9 antigen (DRAP27/CD9) and diphtheria toxin receptor (DTR) were expressed in mouse L cells. L cells transfected transiently with both DRAP27/CD9 and DTR cDNA bound approximately 10 times more diphtheria toxin (DT) than cells transfected with DTR alone. Stable L cell transfectants expressing both DTR and DRAP27/CD9 (LCH-1 cells) had 15 times more cell surface DT-binding sites and were 20 times more sensitive to DT than were stable L cell transfectants expressing DTR alone (LH-1 cells). Increased DT-binding and DT sensitivity were not due to increased DTR transcription or increased cell surface DTR protein. Co-immunoprecipitation of DRAP27/CD9 with DTR and chemical cross-linking suggest a tight association of these membrane-bound proteins. In addition, the identity of DTR and a growth factor (HB-EGF) was established. Immobilized DT specifically adsorbed HB-EGF precursor solubilized from transfected L cells and [125I]DT bound to immobilized recombinant HB-EGF. We conclude that DRAP27/CD9 associates tightly with DTR/HB-EGF and up-regulates the number of functional DTRs and DT sensitivity, and that HB-EGF is identical to DTR.

The 27-kD diphtheria toxin receptor-associated protein (DRAP27) from vero cells is the monkey homologue of human CD9 antigen: expression of DRAP27 elevates the number of diphtheria toxin receptors on toxin-sensitive cells

Diphtheria toxin (DT) receptor associates with a 27-kD membrane protein (DRAP27) in monkey Vero cells. A cDNA encoding DRAP27 was isolated, and its nucleotide sequence was determined. The deduced amino acid sequence revealed that DRAP27 is the monkey homologue of human CD9 antigen. DRAP27 is recognized by CD9 antibodies. A human-mouse hybrid cell line (3279-10) possessing human chromosome 5, sensitive to DT, but not expressing CD9 antigen, was used for transfection experiments with DRAP27. When the cloned cDNA encoding DRAP27 was transiently expressed in 3279-10 cells, the total DT binding capacity was three to four times higher than that of untransfected controls. Transfectants stably expressing DRAP27 have an increased number of DT binding sites on the cell surface. Furthermore, the transfectants are 3-25 times more sensitive to DT than untransfected cells, and the sensitivity of these cells to DT is correlated with the number of DRAP27 molecules on the surface. However, when the cloned cDNA was introduced into mouse cell lines that do not express DT receptors, neither an increased DT binding nor enhancement of DT sensitivity was observed. Hence, we conclude that DRAP27 itself does not bind DT, but serves to increase DT binding and consequently enhances DT sensitivity of cells that have DT receptors. 12 proteins related to DRAP27/CD9 antigen were found through homology search analysis. These proteins appear to belong to a new family of transmembrane proteins.

Intraoperative radiation therapy

1. Local and regional recurrence of disease is a major problem in cancer management. Intraoperative radiation therapy (IORT) combines surgery with irradiation to treat any disease remaining after surgery and to decrease the local recurrence rates for certain cancers. 2. The development of an IORT treatment program is often undertaken by groups and institutions with expertise in multidisciplinary oncology, particularly surgical and radiation oncology. The program uses multiple resources, requiring cooperation and teamwork to achieve an efficient procedure with maximum patient outcome. 3. The process should be reviewed and modified each time it is performed. There is no "standard" way to use IORT, and every program will have variations that adapt to the circumstances existing in each specific facility.

Purification of diphtheria toxin receptor from Vero cells

Diphtheria toxin receptor has been solubilized from Vero cell membranes with octyl beta-D-glucoside. CRM197, the product of a mutated diphtheria toxin gene, was used for the identification of the receptor. The binding activity of the solubilized receptor was assayed by precipitating the receptor with acetone in the presence of phospholipids and carrier proteins. The solubilized receptor was purified by the combination of several chromatographic steps in the presence of the detergent, resulting in about a 10(6)-fold purification of the receptor. The purified receptor showed essentially a single band of 14.5 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When partially purified receptor fractions were subjected to ligand blotting analysis using 125I-CRM197 as the probe, the 14.5-kDa protein and a few minor protein bands were identified as diphtheria toxin-binding molecules. These results show clearly that the 14.5-kDa protein is the diphtheria toxin receptor, or at least the major diphtheria toxin-binding molecule. When partially purified receptor was applied to a Sephacryl S-300 column in the presence of detergent, the receptor was eluted in the fractions corresponding to the 60-90-kDa size range. This suggests that the protein forms a complex with itself or with another protein.

An antibody that inhibits the binding of diphtheria toxin to cells revealed the association of a 27-kDa membrane protein with the diphtheria toxin receptor

A monoclonal antibody that blocks the binding of diphtheria toxin to Vero cells was isolated by immunizing mice with Vero cell membrane. The antibody inhibits the binding of diphtheria toxin and also CRM197, a mutant form of diphtheria toxin, to Vero cells, and consequently inhibits the cytotoxicity of diphtheria toxin. This antibody does not directly react with the receptor molecule of diphtheria toxin (DTR14.5). Immunoprecipitation and immunoblotting studies revealed that this antibody binds to a novel membrane protein of 27 kDa (DRAP27). When diphtheria toxin receptor was passed through an affinity column made with this antibody, the receptor was trapped only in the presence of DRAP27. These results indicate that DRAP27 and DTR14.5 closely associate in Vero cell membrane and that the inhibition of the binding of diphtheria toxin to the receptor is due to the binding of the antibody to the DRAP27 molecule. Binding studies using 125I-labeled antibody showed that there are many more molecules of DRAP27 on the cell surface than diphtheria toxin-binding sites. However, there is a correlation between the sensitivity of a cell line to diphtheria toxin and the number of DRAP27 molecules on the cell surface, suggesting that DRAP27 is involved in the entry of diphtheria toxin into the target cell.

Direct evidence of the Entner-Doudoroff pathway operating in the metabolism of D-glucosamine in bacteria

Pseudomonas fluorescens (Migula) (IFO 14808) has both a membrane-bound PQQ-dependent D-glucose (D-Glc) dehydrogenase [EC 1.1.99.17] [which also acts on D-glucosamine (D-GlcN)] and a PLP-dependent D-glucosaminate (D-GlcNA) dehydratase [EC 4.2.1.26]. Further, these two enzymes were induced when D-GlcN was added to the culture medium. However, D-glucosamine-6-phosphate (D-GlcN-6-P) isomerase [EC 5.3.1.10], another enzyme involved in the metabolism of D-GlcN, was only present at a low level in this bacterium. The bacterium was able to grow in a minimal medium containing D-GlcN or D-GlcNA as the sole source of carbon and nitrogen. Intact cells of P. fluorescens (Migula) converted D-GlcN to D-GlcNA and then to 2-keto-3-deoxy-D-gluconate (KDGA). These results demonstrate that D-GlcN is metabolized via D-GlcNA to KDGA in P. fluorescens (Migula) (Entner-Doudoroff pathway). In contrast, Enterobacter cloacae(IFO 13535) and Agrobacterium radiobacter (IAM 1526) have significant amounts of D-GlcN-6-P isomerase with low levels of the D-Glc dehydrogenase and D-GlcNA dehydratase. Further, only the isomerase activity was induced on the addition of D-GlcN to the culture medium. These results demonstrate that there is a new route (Entner-Doudoroff pathway), i.e., in addition to the known one (Embden-Meyerhof pathway), for the metabolism of D-GlcN in bacteria and one of the two routes is predominant in the each of bacteria examined.

Antibodies to Asp-Asp-Glu-Asp can inhibit transport of nuclear proteins into the nucleus

The signal sequence of simian virus 40 (SV40) large T-antigen for translocation into the nucleus is composed of positively charged amino acids Lys-Lys-Lys-Arg-Lys. Rabbit antibodies to a synthetic peptide containing the negatively charged amino acid sequence Asp-Asp-Asp-Glu-Asp were obtained. Indirect immunofluorescence of the antigens recognized by the antibody was punctate at the nuclear rim or the nuclear surface, depending on the plane of focus. The antibody blocked transport of nuclear proteins into the nucleus. The antigens recognized by the antibody were predominantly localized to the nuclear pores.

ATP-dependent association of nuclear proteins with isolated rat liver nuclei

In vitro association of Xenopus nucleoplasmin and mammalian nonhistone chromosomal high mobility group 1 (HMG1) protein with nuclei isolated from rat liver was examined. Efficient association of nuclear proteins with isolated nuclei requires ATP, HCO3-, and Ca2+. Association occurred at 33 degrees C but not at 4 degrees C. ATP could be replaced by adenosine 5'-[alpha,beta-methylene]triphosphate (pp[CH2]pA), a nonhydrolyzable ATP analog. pp[CH2]pA associated with nuclei at 33 degrees C and nucleoplasmin and HMG1 rapidly associated with the pp[CH2]pA-bound nuclei at 4 degrees C. Competition studies showed that these associations at both 33 degrees C and 4 degrees C were specific. More than 80% of the bindings of nuclear proteins to the nuclear surface were blocked by wheat germ agglutinin.

Quantitative surface analysis of Cardiothane 51 by FT-IR-ATR spectroscopy

Surface analysis has been carried out for Cardiothane 51 samples as commercially available balloon pumps and cast films prepared from the solution. Silicone contents on surfaces have been quantitatively determined by FT-IR-ATR spectroscopy coupled with a subtraction technique. The contents on the air-facing surface vary from 0.7 to 5.3% among six balloon pumps examined; three of them contain less silicone on the air-facing surface than on the substrate-facing surface, whereas just the opposite is true for one, and the other two have nearly and quite an equal content of it between the two surfaces. Silicone contents on surfaces of cast films vary also from a sample to another even when sample films were prepared from the same Cardiothane solution, indicating difficulty in quality control of Cardiothane surfaces. An appreciable fraction of silicone was found not to be covalently bonded to polyurethane in Cardiothane 51 for the cast film samples.

D-glucosaminate dehydratase: spectrometric properties of the enzyme-bound pyridoxal 5'-phosphate

The holoenzyme of D-glucosaminate dehydratase [EC 4.2.1.26] from Agrobacterium radiobacter showed absorption peaks at 280 and 415 nm with a shoulder in the region of 320 to 330 nm. The treatment of the enzyme with hydroxylamine followed by dialysis led to disappearance of both the absorption peak at 415 nm and the shoulder, giving the apoenzyme. The fluorescence excitation maximum of the holoenzyme was at 320 nm with a shoulder at 420 nm (emission at 510 nm), and the emission maxima were at 420 nm with a shoulder at 370 nm (excitation at 320 nm) and at 510 nm (excitation at 420 nm). The holoenzyme showed a negative circular dichroic band at 418 nm and a positive shoulder at around 320 nm. Reduction of the holoenzyme with sodium borohydride caused a loss of the absorption peak at 415 nm with a concomitant increase of 325 nm absorbance and an irreversible loss of the activity. The occurrence of epsilon-N-pyridoxyllysine in the acid hydrolysate of the reduced enzyme showed that D-glucosaminate dehydratase contains a catalytically essential lysine residue whose epsilon-amino group binds the 4-formyl group of pyridoxal 5'-phosphate to form a Schiff base. The plots of absorption of the apoenzyme against the amount of pyridoxal 5'-phosphate added showed that four and two molar equivalents of the cofactor bind to the apoenzyme and subunit, respectively. The biphasic nature of the spectrometric titration curve of the apoenzyme with pyridoxal 5'-phosphate and the two Km values obtained for the cofactor suggest the occurrence of two distinct types of binding sites for pyridoxal 5'-phosphate in the enzyme.

Stereochemistry of an alpha, beta-elimination reaction by D-glucosaminate dehydratase

The proton NMR analysis of D-glucosaminate dehydratase reaction in D2O revealed the incorporation of a deuterium atom at C-3 carbon of the product, 2-keto-3-deoxy-D-gluconate. Based on the chemical shift of C-3 proton of the product and the coupling constant characteristic for the C-3 and C-4 axial-axial coupling in the 2C5 pyranose conformation, the deuterium is in the pro-S position. Thus, the dehydration of D-glucosaminate by the enzyme proceeds in a retention mode at C-3 carbon. Kinetic parameters show that the rate-determining step is the abstraction of alpha-proton from the substrate.

D-glucosaminate dehydratase from Agrobacterium radiobacter. Physicochemical and enzymological properties

The bacterial distribution of D-glucosaminate dehydratase [EC 4.2.1.26] was investigated and Agrobacterium radiobacter (IAM 1526) was found to have the highest enzyme activity. The enzyme was formed inducibly in a glycerol-urea medium by D-glucosamine, D-galactosamine, and D-glucosamine, but not by D-mannosamine. The enzyme purified from the cells grown in the glucosamine-glycerol-urea medium was shown to be homogeneous by ultracentrifugation. The molecular weight was determined to be about 66,000 by the sedimentation equilibrium method, and 72,800 by the gel permeation chromatography low-angle light scattering method. The pH optimum is 8.3-9.0. The enzyme catalyzed the dehydration of D-glucosaminate (relative activity: 100, Km: 2.8 mM), D-galactosaminate (31.5, 5.0 mM), D-mannosaminate (17.5, 29 mM), D-threonine (5.1, 4.8 mM), D-serine (3.2, 0.026 mM), and L-serine (1.1, ND), but not L-threonine. The reverse reaction does not occur. The enzyme is inhibited by typical inhibitors of pyridoxal 5'-phosphate enzymes, such as L'penicillamine, and also by carbonyl reagents, thiol reagents, divalent metals, and several D-amino acids and D-amino sugars.