Characterization of interglobular dentin and Tomes' granular layer in dog dentin using electron probe microanalysis in comparison with predentin

The interglobular dentin (IG) and the Tomes' granular layer (TGL) as well as predentin are hypomineralized regions in dentin. Some previous studies proposed that the IG and the TGL are identical with difference only in size, whereas other suggested that they are distinct structures. In order to characterize their matrix components, the present study was designed to analyze the elements of calcium (Ca), phosphorus (P), and sulfur (S) in the IG and the TGL in comparison with predentin using the Electron Probe Microanalysis (EPMA). The TGL was highest in the concentration of both Ca and P among the hypomineralized regions followed by the IG and predentin, whereas predentin was the highest in the concentration of S followed by the IG and the TGL. Alcian blue staining suggested that the S elements identified with the EPMA are incorporated into the sulfated glycosaminoglycan chains of proteoglycans. The present study first demonstrated distinct characteristics of matrix components in the IG and the TGL, i.e., the IG is poorer in mineralization but much richer in a proteoglycan content than the TGL. The IG may originate from predentin because of their analogy, whereas the TGL may follow a different ontogeny.

Reassessment of monoethylglycinexylidide as preoperative liver function test in a rat model of liver cirrhosis and man

It is known that lidocaine is rapidly metabolized by the hepatic cytochrome P-450 system to form monoethylglycinexylidide (MEGX), its primary metabolite. We analyzed serum MEGX levels experimentally and clinically by fluorescent polarization immunoassay to reassess preoperative liver microsome functions.

EXPERIMENTAL STUDY

Liver cirrhosis was produced in rats by intra-abdominal injection of thioacetamide. MEGX, indocyanine green test (ICG), and liver biochemical variables were measured periodically. Then, survival rates were assessed after the rats received a 70% hepatectomy.

CLINICAL STUDY

MEGX levels were measured in various human patients with chronic hepatitis or liver cirrhosis who underwent hepatectomy. Serum MEGX levels significantly dropped and ICG levels significantly rose with macroscopic and histologic progression of liver cirrhosis in rats. The MEGX levels correlated closely with albumin levels and ICG. Preoperative MEGX and ICG levels of the mortal group of rats differed significantly from those of the survival group with 70% hepatectomy. Furthermore, 100% of the rats with MEGX levels above 40 ng/ml and ICG levels below 1.0%. In the clinical study, MEGX levels were significantly lower in patients with chronic hepatitis or liver cirrhosis than in healthy volunteers and correlated significantly with liver function tests such as albumin, Fischer's ratio, prothrombin time, hepaplastin and ICG. A significant difference was found in MEGX levels between patients receiving lobectomy and those receiving subsegmentectomy or partial hepatectomy. All patients tolerated their operations. Our data indicate that the MEGX test combined with ICG test and Child-Pugh classification is a better predictor of residual liver reserve capacity, and the analysis of hepatic MEGX formation might prove useful for rapid and reliable assessment liver function and choice of surgical treatment.

Propofol versus midazolam regarding their antioxidant activities

Propofol and midazolam are commonly used as sedatives for critically ill patients. These patients usually suffer from the pathologic effects of oxidative stress, predominantly caused by an imbalance between the generation of reactive oxygen species and the antioxidant defense system. Therefore, the antioxidant activities of propofol and midazolam may be of clinical importance. We investigated the activities of these two sedatives against hydrophilic or lipophilic peroxyl radicals in a homogeneous solution and in the presence of erythrocyte membranes. A chemical analysis of the homogeneous solution revealed that propofol efficiently scavenged hydrophilic peroxyl radicals (50% inhibitory concentration [IC50] = 1.3 x 10(-4) M), whereas midazolam efficiently scavenged lipophilic radicals (IC50 = 1.5 x 10(-5) M). Further, in membrane systems, propofol inhibited the oxidative damage induced by either hydrophilic or lipophilic radicals (IC50 = 1.5 x 10(-5) M for hydrophilic radicals and IC50 = 3.0 x 10(-4) M for lipophilic radicals), whereas midazolam did very little. In previous studies, we demonstrated that antioxidant activity is highly affected by the location and properties of the reaction site. The discrepancy in antioxidant activity between a homogeneous condition and in the presence of membranes can be well explained by this concept, and again emphasizes the importance of membranes in determining antioxidant activity. To further understand the biologic significance of these antioxidant properties, the effect of the two agents on endothelium-dependent relaxation was studied. Application of oxidative stress to aortic rings by treating them with peroxyl radicals led to a significant blockade of acetylcholine-induced relaxation after submaximal contraction with phenylephrine. Propofol pretreatment greatly attenuated the impairment in comparison with midazolam, which agrees with the concept of antioxidant activity in the presence of membranes. The results of the present study suggest that propofol has a greater potential to reduce oxidative stress than midazolam.

Suppressive effect of topically applied CX-659S, a novel diaminouracil derivative, on the contact hypersensitivity reaction in various animal models

BACKGROUND

The T-cell-mediated contact hypersensitivity reaction (CHR) is thought to be involved in the pathogenesis of clinical cutaneous disorders including atopic dermatitis. A novel diaminouracil derivative, CX-659S, has been reported to have an inhibitory activity against picryl chloride (PC)-induced CHR when administered either orally or percutaneously. The inhibitory effect of topical CX-659S was assessed in three CHR models in the present study. In addition, to elucidate the mechanism of action of this compound, we examined the effect of CX-659S on the expression of messenger RNAs for proinflammatory cytokines after elicitation in PC models.

METHODS

For the in vivo evaluation of the efficacy of CX-659S, we used PC- or oxazolone-induced CHR in mice and 2,4-dinitrochlorobenzene (DNCB)-induced CHR in guinea pigs. CX-659S was topically applied immediately after the hapten challenge in each model. To assess the effect on gene expression of cytokines, we used the reverse transcriptase-polymerase chain reaction (RT-PCR), a semiquantitative technique with specific primers.

RESULTS

Topical CX-659S dose-dependently inhibited ear swelling at 24 h after the challenge in the two mouse models. This inhibitory effect was histologically confirmed in the PC model. Topically applied CX-659S also inhibited erythema and edema formation 24 h after challenge in the guinea pig model. CX-659S inhibited the expression of mRNA for proinflammatory cytokines IL-1 beta and TNF-alpha in vivo.

CONCLUSIONS

Topically applied CX-659S showed significant inhibitory activities against CHR models both in mice and in guinea pigs. Inhibition profiles of CX-659S toward mRNA expression for proinflammatory cytokines corroborated these findings. CX-659S thus could be a useful therapeutic agent for allergic cutaneous disorders such as allergic contact dermatitis and atopic dermatitis.

Mouse T-cell antigen rt6.1 has thiol-dependent NAD glycohydrolase activity

Mouse Rt6.1 and Rt6.2, homologues of rat T-cell RT6 antigens, catalyze arginine-specific ADP-ribosylation. Without an added ADP-ribose acceptor, Rt6.2 shows NAD glycohydrolase (NADase) activity. However, Rt6.1 has been reported to be primarily an ADP-ribosyltransferase, but not an NADase. In the present study, we obtained evidence that recombinant Rt6.1 catalyzes NAD glycohydrolysis but only in the presence of DTT. The NADase activity of Rt6.1 observed in the presence of DTT was completely inhibited by N-ethylmaleimide (NEM). Native Rt6.1 antigen, immunoprecipitated from BALB/c mouse splenocytes with polyclonal antibodies generated against recombinant RT6.1, also exhibited NADase activity in the presence of DTT. Compared with Rt6.2, Rt6.1 has two extra cysteine residues at positions 80 and 201. When Cys-80 and Cys-201 in Rt6.1 were replaced with the corresponding residues of Rt6.2, serine and phenylalanine, respectively, Rt6.1 catalyzed the NADase reaction even in the absence of DTT. Conversely, replacing Ser-80 and Phe-201 in Rt6.2 with cysteines, as in Rt6.1, converted the thiol-independent Rt6.2 NADase to a thiol-dependent enzyme. Kinetic study of the NADase reaction revealed that the affinity of Rt6.1 for NAD and the rate of catalysis increased in the presence of DTT. Moreover, the NADase activity of Rt6.1 expressed on COS-7 cells was stimulated by culture supernatant from activated mouse macrophages, even in the absence of DTT. From these observations, we conclude that t!he Rt6.1 antigen has thiol-dependent NADase activity, and that Cys-80 and Cys-201 confer thiol sensitivity to Rt6.1 NADase. Our results also suggest that upon the interaction of T-cells expressing Rt6.1 with activated macrophages, the NADase activity of the antigen will be stimulated.

Interrelation between oxygen tension and nitric oxide in the respiratory system

To understand the relationship between oxygen tension and nitric oxide (NO) function, one animal and two human studies were designed. In the animal study, the effect of NO in inducing the relaxation of aortic specimens was significantly lower by 68% under 480 mm Hg of oxygen tension than under 28 mm Hg, indicating that oxygen tension has an important role in determining the biological effects of NO. In a clinical analysis with nonsmokers (n = 23), the alveolar-to-arterial difference for oxygen (A-aDO(2)) was reciprocally correlated with exhaled NO concentrations (r = 0.53). Because NO concentration in the lower respiratory zone depends partly on the amount of inspirable NO originating in the upper airway, a well-ventilated area, requiring much perfusion, could receive greater amounts of NO than a poorly ventilated one. Thus, the reciprocal relation of A-aDO(2) with the concentration of exhaled NO is not necessarily incompatible with the effect of hypoxic pulmonary vasoconstriction in ventilation-to-perfusion (V'A/Q') imbalance. In our third experiment, with nonsmokers (n = 21), pure oxygen inhalation during mechanical ventilation significantly decreased the concentration of exhaled NO and enhanced A-aDO(2), indicating a relationship between NO and oxygen similar to that observed in the animal experiment. These findings led us to conclude that a positive relation between exhaled NO and blood oxygenation efficiency exists in the respiratory system, and further, that oxygen might affect this relationship. Thus, the relative balance of NO and oxygen concentrations may be another factor for consideration in respiratory function.

Immunogenetic background of patients with autoimmune fatigue syndrome

We have previously reported that approximately 50% of children with chronic nonspecific complaints were positive for antinuclear antibodies (ANA), and that a novel autoantibody to a 62 kD protein (anti-Sa) was found in 40% of these ANA-positive patients. Therefore, we proposed a distinct disease entity termed autoimmune fatigue syndrome (AIFS). We hypothesized that if autoimmune mechanisms did play an important role in the pathogenesis of AIFS, it is possible that it is immunogenetically regulated as observed in other autoimmune disorders. In order to examine the immunogenetic background of AIFS patients, HLA-A, -B, -C, and -DR loci were analyzed serologically in 61 AIFS patients. AIFS was found to be positively associated with the class I antigen HLA-B61 and with the class II antigen HLA-DR9, with odds ratios of 2.77 (p = 0.015, Pcorr = 0.48) and 2.60 (p= 0.012, Pcorr = 0.17), respectively. A negative association was also found between AIFS and HLA-DR2 with odds ratio of 0.25 (p = 0.029, Pcorr = 0.041). When comparing anti-Sa positive AIFS patients with healthy controls, the odds ratios associated with HLA-B61, DR9, and DR2 were 3.42 (p = 0.021, Pcorr = 0.22), 3.96 (p = 0.0011, Pcorr = 0.015), and 0.16 (p = 0.0022, Porr = 0.031), respectively. Thus, the HLA associations observed in this study suggested that immunogenetic background might play a role in AIFS.

Expression of steroidogenic acute regulatory protein (StAR) in rat granulosa cells

Steroidogenic acute regulatory protein (StAR) is a vital mitochondrial protein that is indispensable for the synthesis of steroids. To study the mechanisms of regulation of StAR in rat granulosa cells, we used granulosa cells obtained from diethylstilbestrol-treated immature rats. Northern blot analysis revealed two major transcripts of about 3.6 kb and 1.6 kb of rat StAR mRNA. Rat StAR mRNA had strongly increased within 2 h due to the treatment of FSH or 8-Br-cAMP in this culture, a parallel increase of transcripts of both sizes was observed. Compared to the control, StAR mRNA levels increased in a dose-dependent manner in the presence of increasing concentrations of FSH (1-100 ng/ ml) and 8-Br-cAMP (0.25-5 mM). Although co-treatment of rat granulosa cells with FSH and TGF-beta did not change FSH-induced StAR mRNA levels, these levels in granulosa cells were markedly increased by pretreatment with TGF-beta before being acutely (2 h) stimulated with an effective dose of FSH. The stimulatory effect of TGF-beta was time- and concentration-dependent (1-30 ng/ml).

Guinea pig D-amino-acid oxidase cDNA and phylogenetic position

The nucleotide sequence of cDNA that encodes guinea pig D-amino-acid oxidase (DAO) was determined. The cDNA consisted of 1,399 nucleotides and a poly(A) tail. The cDNA encodes 347 amino acid residues. In contrast to the hamster, rat, and mouse DAOs, guinea pig DAO had the 25th amino acid residue. The homology in amino acid sequences between the guinea pig DAO and the rodent DAOs was not high in comparison to the homology in amino acid sequences between the guinea pig DAO and DAOs of humans, pigs and rabbits. The phylogenetic position of the guinea pig varied depending on the source of sequences (amino acids or nucleotides) and the methods of phylogenetic tree construction. These results suggest that the guinea pig is not a simple rodent.

Synthesis and biological evaluation of CX-659S and its related compounds for their inhibitory effects on the delayed-type hypersensitivity reaction

In order to find novel nonsteroidal compounds possessing an inhibitory activity against delayed-type hypersensitivity (DTH) reactions, we conducted random screening using a picryl chloride (PC)-induced contact hypersensitivity reaction (CHR) in mice, and found compound 1 as a lead compound. Then we synthesized and evaluated an extensive series of 5-carboxamidouracil derivatives focused on both the uracil and the antioxidative moieties. Among them, we found that the hindered phenol moiety was necessary to exhibit the activities; especially, compounds 28a-28c having the partial structure of vitamin E were found to exert potent activities against the DTH reaction by both oral and topical administration. And compound 28c showed antioxidative activity against lipid peroxidation with an IC50 of 5.9 microM. Compound 28c (CX-659S) was chosen as a candidate drug for the treatment of cutaneous disorders such as atopic dermatitis and allergic contact dermatitis.

Efficacy of a continuous syringe extraction method for monitoring hemodialysis ultrafiltrate

The evaluation of hemodialysis ultrafiltrate is essential for the assessment of uremic toxins, dialyzer net performance, protein catabolic rate, and safety and environmental protection. Total dialysate collection (TDC), however, is technically far from the daily procedure used. In the present study, use of a continuous syringe extraction method (CSEM) as a substitute for TDC was tested to determine its comparative effectiveness. Measurements of urea nitrogen, creatinine, phosphate, beta2-microglobulin, and albumin were simultaneously obtained by both TDC and CSEM in 20 dialysis sessions. CSEM showed an extremely significant correlation with TDC for these values. The correlation coefficients were >0.97 for these indicators and the value of Fisher's r to z were all <0.001. Taken together, these data indicate that CSEM is an effective substitute for TDC. With use of CSEM, the evaluation of spent dialysate could become as a daily procedure.

A histochemical study of inflammatory lesions of the maxillary sinus mucosa using biotinylated lectins

The distribution of glycoconjugates in normal maxillary sinus tissues, in cases of maxillary sinusitis and in postoperative maxillary cysts (POMC), was examined using seven different lectins as probes. The results showed that wheatgerm agglutinin (WGA), peanut agglutinin (PNA), Ulex europaeus agglutinin-1 (UEA-1), Ricinus communis agglutinin-1 (RCA-1), and concanavalin A (ConA) strongly react with the cilia and goblet cells. The binding of WGA, PNA, UEA-1, and RCA-1 was increased in maxillary sinusitis and POMC compared with normal maxillary sinus epithelium, whereas that of ConA was decreased. The decreased binding of ConA suggested that there were fewer mannoside residues in the maxillary sinus epithelium in the inflammatory lesion. The PNA bound to the cilia, goblet cells and mucous glandular cells in maxillary sinusitis and POMC, but not in normal, uninflamed cells, indicating that D-galactose was produced by the inflammatory condition. Similar binding patterns of PNA and RCA-1 were found in the cilia and on the surface of the epithelium and in the goblet cells. It is assumed that the carbohydrate moiety in the sinus mucosa is altered in inflammatory conditions.

Role of nuclear factor-kappaB in the expression by tumor necrosis factor-alpha of the human polymeric immunoglobulin receptor (plgR) gene

We analyzed the mechanism of human polymeric immunoglobulin receptor (pIgR) gene upregulation by tumor necrosis factor (TNF)-alpha. Northern blot analysis showed that the expression of pIgR mRNA was enhanced by TNF-alpha stimulation. This activation was completely inhibited by RNA polymerase or protein synthesis inhibitors, suggesting that the regulation of pIgR gene expression depends on de novo RNA and protein synthesis. Furthermore, the stimulation of pIgR mRNA by TNF-alpha was decreased by pyrrolidinedithiocarbamate and L-1-4'-tosylamino-phenylethyl-chloromethyl ketone, which are known nuclear factor (NF)-kappaB inhibitors. For further analysis of gene regulation, we cloned and sequenced the 1.5-kb 5'-flanking region of the pIgR gene. In the upstream region, we found two NF-kappaB-binding motifs (named kappaB1 and kappaB2 from the 5' region). An electrophoretic mobility shift assay indicated that two components of the NF-kappaB/Re1 family, p50 and p65, bound with higher affinity to the KB2 element than to the kappaB1 element. We also analyzed plgR gene expression using reporter plasmids expressing the firefly luciferase gene. Stimulation by TNF-alpha significantly activated the pIgR gene promoter, as a 775-bp upstream region of the pIgR gene increased luciferase gene expression in cells treated with TNF-alpha. The activation of promoter activity by TNF-alpha was abolished when a mutation was inserted into kappaB1 or kappaB2. These data indicated that pIgR gene expression induced by TNF-alpha is transcriptionally regulated via activation of NF-kappaB. In addition, there is a possibility that another factor may act in concert with NF-kappaB.

Confocal microscopy of Tomes' granular layer in dog premolar teeth

Tomes' granular layer is the hypomineralized area of radicular dentin, but knowledge concerning it is limited. The present study was designed to investigate the structural characteristics of Tomes' granular layer in the dog's teeth by confocal microscopy. Permanent premolars of four beagles, two at 7 months and the other two at 14 months of age, were used for observation. During premolar root formation, the 7-month-old dogs were injected with calcein and alizarin red S for vital staining of dentin, and ground sections of the teeth were prepared. Both ground and decalcified-paraffin sections were made from the teeth of the 14-month-old dogs and stained with basic fuchsin or with hematoxylin and eosin. All sections were examined by fluorescence and confocal microscopy. In the ground sections, granules of Tomes' layer and dentinal tubules were stained with basic fuchsin and with calcein. The granules of Tomes' layer stained with calcein were seen only near the labeling lines by calcein. The granules of Tomes' layer appeared as bright spots in cross sections, and as lines in longitudinal sections. When the sections were cut tangentially through the surface of dentin, the granules of Tomes' layer showed a reticular structure. Most of the dentinal tubules were seen to pass between the granules and terminated in the dentin-cementum junction. Looped tubules were not found in this area. In the paraffin sections stained with hematoxylin and eosin, extracellular matrix of dentin showed fluorescence of various intensities and dentinal tubules appeared dark. At the surface of the radicular dentin, the granules of Tomes' layer appeared as fluorescent fibers running parallel to the surface of dentin in the longitudinal sections. The fibers appeared as bright spots in the cross sections and as a mesh in the tangential sections. In the periodontal ligament, collagen fibers showed intense fluorescence, whereas most cells were negative. From these results we conclude that Tomes' granular layer of dog's teeth may be the collagen fiber bundles that remained uncalcified or hypocalcified within the radicular dentin.

[The anesthetic management for elective or emergent cesarean section in patients with intracranial arteriovenous malformation]

Subarachnoid hemorrhage secondary to ruptured intracranial arteriovenous malformation (AVM) during pregnancy, although rare, is a grave complication. We experienced 3 patients with AVM for cesarean section. Case 1: A 24-year-old woman suffered sudden vomiting and headache during the 22nd week of her first pregnancy. She was diagnosed as having the intracranial hemorrhage due to AVM. Because the patient was bleeding again at 29th week of pregnancy, emergency operation was performed. Her neurological symptom improved. Cesarean section was performed under general anesthesia at 34th week of pregnancy. Case 2: A 42-year-old woman of her first pregnancy had past history of subarachnoid hemorrhage due to AVM at the ages of 23, 28, 29 and 36. The malformation was not corrected surgically. Her neurological status was normal. Cesarean section was performed under spinal anesthesia. Case 3: A 29-year-old woman suffered sudden hemiplegia, vomiting and headache during the 40th week of her first pregnancy. She was diagnosed as having intracranial hemorrhage. Cesarean section immediately followed by the removal of an intra cranial hematoma under general anesthesia. Better perinatal outcome is expected when AVM rerupture is prevented by first performing cesarean section.

Pharmacokinetics of ezlopitant, a novel non-peptidic neurokinin-1 receptor antagonist in preclinical species and metabolite kinetics of the pharmacologically active metabolites

The pharmacokinetics of ezlopitant were determined in the rat, gerbil, guinea pig, ferret, dog and monkey after intravenous and oral administration. In general, ezlopitant is marked by high clearance values that approach or exceed hepatic blood flow values, moderate to high values for steady-state volume of distribution (3. 9-28 L/kg), and terminal phase half-life values ranging from 0.6 h in the guinea pig to 7.7 h in the rat. Oral bioavailability ranged from <0.2% (guinea pig) to 28% (dog). Data from portal vein cannulated dogs suggested that 37% of an oral dose of ezlopitant enters the portal vein as an unchanged drug in this species. Ezlopitant is metabolized to two pharmacologically active metabolites, an alkene (CJ-12 458) and a benzyl alcohol (CJ-12 764). After administration of the parent compound, CJ-12 764 was found in greater abundance than CJ-12 458 in all species examined. Ezlopitant and CJ-12 458 were highly protein bound in plasma (or serum), whereas the protein binding of CJ-12 764 was somewhat lower. Measurement of the kinetics of ezlopitant, CJ-12 458 and CJ-12 764 in the cerebrospinal fluid (CSF) of dogs demonstrated that all three compounds can partition into the CSF, and thereby, be capable of contributing to centrally mediated pharmacological effects. Thus, these data suggest that the pharmacological activity exhibited by ezlopitant in preclinical species in vivo is likely a result of the parent compound plus the active metabolites. Furthermore, the contributions of ezlopitant and the active metabolites to pharmacological activity probably varies with the identity of the model species, as well as the dose and route of ezlopitant administration.

Job search and employment-related issues in athletic training education programs

OBJECTIVE

To investigate the amount of classroom instruction appropriated for employment-related issues and how career service centers were used by students in National Athletic Trainers' Association (NATA)-approved/Commission on Accreditation of Allied Health Education Programs (CAAHEP)-accredited undergraduate athletic training curriculums.

DESIGN AND SETTING

We developed a job placement survey and mailed it to subjects. The study was conducted through the School of Physical Education at West Virginia University.

SUBJECTS

The subjects were all undergraduate athletic training curriculum directors employed in an NATA-approved or CAAHEP-accredited program.

MEASUREMENTS

We developed a survey instrument based on our experiences with instructional and educational issues in athletic training. The survey instrument consisted of items that investigated the amount of classroom time and education devoted to different aspects of preparing athletic training students for the job market.

RESULTS

A total of 74 surveys were returned, for an 88% return rate. Eighty-six percent of the curriculum directors spent an average of 116 minutes (mean = 116 +/- 142.09; range, 5 to 780) instructing students about employment issues. Curriculum directors spent 63 minutes (mean = 63 +/- 47.86; range, 10 to 270) instructing students on how to develop a résumé. Most curriculum directors (74%) spent time with students discussing how to prepare for an interview (mean = 51 +/- 47.07 minutes; range, 1 to 270). Nearly all curriculum directors (97%) responded that students learned about recognizing allied health postgraduate career options other than athletic training. College or university career service centers were available to 96% of students, but only 53% sought instructional assistance from them. Curriculum directors spent an average of 38 +/- 49.31 minutes (range, 15 to 120) discussing programs available at career service centers.

CONCLUSIONS

Athletic training curriculum directors were providing basic employment preparation skills to students. However, a wide variance existed for time allotted to employment- related issues. Additional research is needed to compare employment instructional methods with program success rates for job placement within athletic training.

Enkephalinergic neurons express 5-HT3 receptors in the spinal cord dorsal horn: single cell RT-PCR analysis

The analgesic effect of activation of 5-HT3 receptors at the spinal cord is attenuated by the opioid antagonist naloxone. Enkephalin-immunoreactive neurons in the spinal cord superficial dorsal horn are innervated by 5-HT-immunoreactive fibers. This prompted us to examine whether enkephalinergic dorsal horn neurons express 5-HT3 receptors. Using the technique of single-cell RT-PCR adapted for small neurons in the superficial dorsal horn, methionine-enkephalin sequence-specific PCR products were observed in about half of the neurons studied. Furthermore, 5-HT3 receptor mRNA was detected in approximately 25% of enkephalinergic neurons. These observations suggest that at least part of the antinociception elicited by activation of 5-HT3 receptors at the spinal cord may involve enkephalinergic dorsal horn neurons.

Isothiazolone derivatives selectively inhibit telomerase from human and rat cancer cells in vitro

The telomere hypothesis postulates stabilization of telomere length and telomerase activation as key events in cellular immortalization and carcinogeneses. Accordingly, telomerase has been suggested as a novel and highly selective target for design of antitumor drugs. Screening of a chemical library including 16 000 synthetic compounds yielded six that strongly inhibited telomerase activity in extracts of cultured human cells, including four isothiazolone derivatives and two unrelated compounds. The most potent inhibitor was 2-[3-(trifluoromethyl)phenyl]isothiazolin-3-one (TMPI), a concentration of 1.0 microM inhibited telomerase activity by 50% according to a telomere repeat amplification protocol (TRAP) assay. Analysis using partially purified telomerase from AH7974 rat hepatoma cells demonstrated noncompetitive inhibition with the telomere-repeat primer and mixed inhibition with the dNTPs; the inhibition constant was 2.5 microM. TMPI did not inhibit eukaryotic DNA polymerase alpha, beta, or human immunodeficiency virus reverse transcriptase (HIV RT). Thus, inhibition by TMPI was highly selective for telomerase. Inhibition by TMPI was quenched by 1 mM of dithiothreitol or glutathione, suggesting that TMPI inhibits telomerase by acting at a cysteine residue. TMPI inhibition of this enzyme may find application as an antineoplastic agent.

A novel strategy for identifying differential gene expression: An improved method of differential display analysis

We propose a novel alternative approach, an advanced method for recently developed strategies, for identifying differentially expressed genes. Firstly, double-stranded cDNAs were digested using Sau3AI and the 3'-end restriction fragments of the cDNA were ligated to a double-stranded adapter. Next, the restriction fragments were directly amplified using several combinations of adapter-specific primers and FITC-labeled oligo dT primers. The selected cDNA fragments were displayed on a polyacrylamide gel. Neither nested PCR nor purification of 3'-end fragments are necessary. We examined the validity of this approach by evaluating gene expression changes during granulocytic differentiation of HL-60 cells. This method can theoretically detect almost all gene expression changes more rapidly and through simpler manipulations than by any other approach.

High-quality sub-100-fs optical pulse generation by fiber-optic soliton compression of gain-switched distributed-feedback laser-diode pulses in conjunction with nonlinear optical fiber loops

We report our investigations of a new and simpler femtosecond fiber-optic soliton compressor for chirp-compensated gain-switched diode-laser pulses and of pedestal suppression by a compound fiber loop mirror (CFLM) and nonlinear-optical loop mirrors (NOLM's), both of which are designed for sub-100-fs pulse generation of high quality. The soliton compressor, composed of a 21.1-m-long steplike dispersion profiled fiber, exhibited 44-fs pulses and a compression ratio of approximately 60. Pedestals of 100-fs soliton pulses were suppressed successfully (>20 dB) by the CFLM and the NOLM's. In particular, 63-fs pedestal-free sech(2) pulses were obtained by NOLM propagation.

Generation of ultraviolet (335-nm) light by intracavity frequency doubling from active mode-locking action of an external-cavity AlGaInP diode laser

An intracavity frequency-doubling scheme was merged with an actively mode-locked AlGaInP laser diode with an external cavity to provide efficient generation of 335-nm ultraviolet light. Intense pulses of <16ps were successfully generated inside the cavity at subgigahertz repetition frequencies. We applied those pulses to intracavity second-harmonic generation from a 5-mm-long LiIO(3) crystal, which resulted in average ultraviolet power of 70muW for an average fundamental power of 73 mW.