Fingolimod Potentiates the Antifungal Activity of Amphotericin B

Candida albicans (C. albicans) is an opportunistic human fungal pathogen that can cause severe infection in clinic. Its incidence and mortality rate has been increasing rapidly. Amphotericin B (AMB), the clinical golden standard antifungal agent, has severe side effects that limit its clinical application. Thus, lowering the concentration and increasing the efficacy of AMB in a combinatorial antifungal therapy have been pursued by both industry and academia. Here we identify that fingolimod (FTY720), an immunomodulatory drug used for oral treatment of relapsing-remitting multiple sclerosis, can potentiate the efficacy of AMB against C. albicans growth synergistically. Furthermore, we observe an antifungal efficacy of FTY720 in combination with AMB against diverse fungal pathogens. Intriguingly, cells treated with both drugs are hypersensitive to endothelial endocytosis and macrophage killing. This is later found to be due to the hyperaccumulation of reactive oxygen species and the corresponding increase in activities of superoxide dismutase and catalase in the cells that received combinatorial treatment. Therefore, the combination of AMB and FTY720 provides a promising antifungal strategy.

Antiphosphatidylserine/prothrombin antibodies (aPS/PT) as potential diagnostic markers and risk predictors of venous thrombosis and obstetric complications in antiphospholipid syndrome

BACKGROUND

The aim of the study was to determine the prevalence and clinical associations of antiphosphatidylserine/prothrombin antibodies (aPS/PT) with thrombosis and pregnancy loss in Chinese patients with antiphospholipid syndrome (APS) and seronegative APS (SNAPS).

METHODS

One hundred and eighty six Chinese patients with APS (67 primary, 119 secondary), 48 with SNAPS, 176 disease controls (79 systemic lupus erythematosus [SLE], 29 Sjogren's syndrome [SS], 30 ankylosing spondylitis [AS], 38 rheumatoid arthritis [RA]) and 90 healthy donors were examined. IgG and IgM aPS/PT, IgG/IgM/IgA anticardiolipin (aCL) and IgG/IgM/IgA anti-β2-glycoprotein I (anti-β2GPI) antibodies were tested by ELISA.

RESULTS

One hundred and sixty (86.0%) of APS patients were positive for at least one aPS/PT isotype. One hundred and thirty five (72.6%) were positive for IgG aPS/PT, 124/186 (66.7%) positive for IgM aPS/PT and 99 (53.2%) positive for both. Approximately half of the SNAPS patients were positive for IgG and/or IgM aPS/PT. Highly significant associations between IgG aPS/PT and venous thrombotic events (odds ratio [OR]=6.72) and IgG/IgM aPS/PT and pregnancy loss (OR=9.44) were found. Levels of IgM aPS/PT were significantly different in APS patients with thrombotic manifestations and those with fetal loss (p=0.014). The association between IgG/IgM aPS/PT and lupus anticoagulant (LAC) was highly significant (p<0.001). When both were positive, the OR for APS was 101.6. Notably, 91.95% (80/87) of LAC-positive specimens were positive for IgG and/or IgM aPS/PT, suggesting aPS/PT is an effective option when LAC testing is not available.

CONCLUSIONS

Anti-PS/PT antibody assays demonstrated high diagnostic performance for Chinese patients with APS, detected some APS patients negative for criteria markers and may serve as potential risk predictors for venous thrombosis and obstetric complications.

Pharmacokinetics, bioavailability and PK/PD relationship of cefquinome for Escherichia coli in Beagle dogs

The pharmacokinetics and bioavailability of cefquinome in Beagle dogs were determined by intravenous (IV), intramuscular (IM) or subcutaneous (SC) injection at a single dose of 2 mg/kg body weight (BW). The minimum inhibitory concentrations (MIC) of cefquinome against 217 Escherichia coli isolated from dogs were also investigated. After IV injection, the plasma concentration-time curve of cefquinome was analyzed using a two-compartmental model, and the mean values of t1/2α (h), t1/2β (h), Vss (L/kg), ClB (L/kg/h) and AUC (μg·h/mL) were 0.12, 0.98, 0.30, 0.24 and 8.51, respectively. After IM and SC administration, the PK data were best described by a one-compartmental model with first-order absorption. The mean values of t1/2Kel , t1/2Ka , tmax (h), Cmax (μg/mL) and AUC (μg·h/mL) were corresponding 0.85, 0.14, 0.43, 4.83 and 8.24 for IM administration, 0.99, 0.29, 0.72, 3.88 and 9.13 for SC injection. The duration of time that drug levels exceed the MIC (%T > MIC) were calculated using the determined MIC90 (0.125 μg/mL) and the PK data obtained in this study. The results indicated that the dosage regimen of cefquinome at 2 mg/kg BW with 12-h intervals could achieve %T > MIC above 50% that generally produced a satisfactory bactericidal effect against E. coli isolated from dogs in this study.

Reduced GABA(A) receptor α6 expression in the trigeminal ganglion alters inflammatory TMJ hypersensitivity

Trigeminal ganglia neurons express the GABA(A) receptor subunit alpha 6 (Gabrα6) but the role of this particular subunit in orofacial hypersensitivity is unknown. In this report the function of Gabrα6 was tested by reducing its expression in the trigeminal ganglia and measuring the effect of this reduction on inflammatory temporomandibular joint (TMJ) hypersensitivity. Gabrα6 expression was reduced by infusing the trigeminal ganglia of male Sprague Dawley rats with small interfering RNA (siRNA) having homology to either the Gabrα6 gene (Gabrα6 siRNA) or no known gene (control siRNA). Sixty hours after siRNA infusion the rats received a bilateral TMJ injection of complete Freund's adjuvant to induce an inflammatory response. Hypersensitivity was then quantitated by measuring meal duration, which lengthens when hypersensitivity increases. Neuronal activity in the trigeminal ganglia was also measured by quantitating the amount of phosphorylated ERK. Rats in a different group that did not have TMJ inflammation had an electrode placed in the spinal cord at the level of C1 sixty hours after siRNA infusion to record extracellular electrical activity of neurons that responded to TMJ stimulation. Our results show that Gabrα6 was expressed in both neurons and satellite glia of the trigeminal ganglia and that Gabrα6 positive neurons within the trigeminal ganglia have afferents in the TMJ. Gabrα6 siRNA infusion reduced Gabrα6 gene expression by 30% and significantly lengthened meal duration in rats with TMJ inflammation. Gabrα6 siRNA infusion also significantly increased p-ERK expression in the trigeminal ganglia of rats with TMJ inflammation and increased electrical activity in the spinal cord of rats without TMJ inflammation. These results suggest that maintaining Gabrα6 expression was necessary to inhibit primary sensory afferents in the trigeminal pathway and reduce inflammatory orofacial nociception.

Resistin level is positively correlated with thrombotic complications in Southern Chinese metabolic syndrome patients

BACKGROUND

The metabolic syndrome (MetS) has been found to be closely related with thrombotic diseases. The mechanism, however, is far from elucidated.

AIM

This study was designed to investigate the relationship between endogenous resistin and thrombosis mediating factors, as well as its potential effects on the gene expression of cardiovascular disease biomarkers.

METHODS

Ninety patients satisfied the MetS criteria, and 55 healthy subjects were recruited as part of a single-center clinical study. Plasma levels of resistin, tissue factor (TF), tissue factor pathway inhibitor (TFPI), tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1) were measured by enzymelinked immunosorbent assays. The effect of resistin on the expression of cardiovascular disease biomarkers in human umbilical vein endothelial cells (HUVEC) was assayed by gene microarray.

RESULTS

1) The average levels of resistin in MetS patients with or without acute myocardial or cerebral infarction were significantly higher than those of the controls. 2) The TF and TFPI increase was higher in MetS with infarction patients than in MetS patients. 3) In MetS with infarction patients, resistin was positively correlated with TF and PAI-1 (r=0.313, p=0.008; r=0.401, p=0.002, respectively). 4) In HUVEC, the microarray showed that apolipoprotein C-I, ACE, tumor necrosis factor receptor superfamily member 1A (TNFRSF1A) and member 5 (CD40) genes expression were dramatically increased by resistin.

CONCLUSION

In patients with MetS, resistin is strongly associated with hypercoagulative and hypofibrinolitic activities. Moreover, resistin may induce thrombotic complications via mediating the lipoprotein metabolism and stimulating inflammation.

Rapid hemodilution is associated with increased sepsis and mortality among patients with severe acute pancreatitis

BACKGROUND

Hemoconcentration may be an important factor that determines the progression of severe acute pancreatitis (SAP). In addition, it has been proposed that biomarkers may be useful in predicting subsequent necrosis in SAP. However, it is still uncertain whether hemodilution in a short term can improve outcome. We aimed to investigate the effect of rapid hemodilution on the outcome of patients with SAP.

METHODS

One hundred and fifteen patients were admitted prospectively according to the criteria within 24 hours of SAP onset. Patients were randomly assigned to either rapid hemodilution (hematocrit (HCT) < 35%, n = 56) or slow hemodilution (HCT > or = 35%, n = 59) within 48 hours of onset. Balthazar CT scores were calculated on admission, day 7, and day 14, after onset of the disease. Time interval for sepsis presented, incidence of sepsis within 28 days and in-hospital survival rate were determined.

RESULTS

The amount of fluid used in rapid hemodilution was significantly more than that used in slow hemodilution (P < 0.05) on the admission day, the first day, and the second day. There were significant differences between the rapid and slow hemodilution group in terms of hematocrit, oxygenation index, pH values, APACHE II scores and organ dysfunction at different time during the first week. There were significant differences in the time interval to sepsis in rapid hemodilution ((7.4 +/- 1.9) days) compared with the slow hemodilution group ((10.2 +/- 2.3) days), and the incidence of sepsis (78.6%) was higher in the rapid group compared to the slow (57.6%) in the first 28 days. The survival rate of the slow hemodilution group (84.7%) was better than the rapid hemodilution (66.1%. P < 0.05).

CONCLUSIONS

Rapid hemodilution can increase the incidence of sepsis within 28 days and in-hospital mortality. Hematocrit should be maintained between 30%-40% in the acute response stage.

Does testosterone prevent early postoperative complications after gastrointestinal surgery?

AIM: To investigate the role of sex hormones in the early postoperative complications of gastrointestinal diseases.

METHODS: A total of 65 patients who underwent operations for gastric and colorectal diseases (mainly malignant diseases) were included in the study. Peripheral venous blood samples were collected at different times for analysis of estradiol, testosterone and progesterone. The only study endpoint was analysis of postoperative complications.

RESULTS: Patients of both sexes were uniform but postoperative complication rate was significantly higher in female patients (P = 0.027). There was no significant association of estradiol and progesterone with postoperative complications. Testosterone levels in complicated patients were significantly lower than in uncomplicated patients (P < 0.05). Area under the receiver operating characteristic curve showed that a lower value of testosterone was a predictor for higher complication rate (P < 0.05), and a lower value of testosterone at later times after surgery was a better predictor of complications.

CONCLUSION: Patients with low testosterone level were prone to higher postoperative complications, which was evident in both sexes. However, further studies are necessary to support this result.

Molecular characterization and expression pattern of the porcine STARS, a striated muscle-specific expressed gene

STARS (striated muscle activator of Rho signaling) promotes the nuclear localization of MRTFs and mediates SRF transcription, which provides a potential muscle-specific mechanism for linking changes in the actin cytoskeleton structure with muscle gene expression. In this study, the full-length cDNA of the porcine STARS was cloned. The open reading frame of this gene contains 1,155 bp and encodes a protein of 384 amino acids, which is 79, 73, and 77% identical with human, mouse, and rat STARS genes, respectively. RT-PCR revealed that STARS is specifically expressed in heart and skeletal muscles. STARS is also distinctly different in different muscle developmental stages. The result indicates that its expression increased gradually from 33 dpc (days postcoitum) to postnatal muscles, and peaked 28 days postnatal. The porcine STARS was mapped to SSC4p13 using the somatic cell hybrid panel and the radiation hybrid panel IMpRH (LOD score 11.98). The data show that STARS is closely linked to marker SW871. A T/G single nucleotide polymorphism in the coding sequence, detected as Bsh1236I PCR-RFLP, displays allele frequency differences in six pig breeds.

Abscisic acid-specific binding sites in the flesh of developing apple fruit

Abscisic acid (ABA) specific-binding sites localized in the cytosol were identified and characterized in the flesh of developing apple (Malus pumila L. cv. Starkrimon) fruit. ABA binding activity was scarcely detectable in the microsomes but high ABA binding activity in the cytosolic fraction was detected. The ABA-binding sites possessed a protein nature with both active serine residues and thiol-groups of cysteine residues in their functional binding sites. ABA binding was shown to be saturable, reversible and of high affinity. A Scatchard plot provided evidence for two different ABA binding proteins, one with higher affinity (K(d)=2.3 nM) and the other with lower affinity (K(d)=58.8 nM). Phaseic acid, trans-ABA and (-)-ABA had essentially no affinity for the binding proteins, indicating their stereo-specificity to bind physiologically active cis-(+)-ABA. The time-course, pH- and temperature-dependence of the ABA-binding proteins were determined. It is hypothesized that the detected ABA-binding proteins may be putative ABA-receptors that mediate ABA signals during fruit development.

GABA(A) and 5-HT(3) receptors are involved in dorsal root reflexes: possible role in periaqueductal gray descending inhibition

The dorsal root reflex (DRR) is a measure of the central excitability of presynaptic inhibitory circuits in the spinal cord. Activation of the periaqueductal gray (PAG), a center for descending inhibition of spinal cord nociceptive transmission, induces release of variety of neurotransmitters in the spinal cord, including GABA and serotonin (5-HT). GABA has been shown to be involved in generation of DRRs. In this study, pharmacological agents that influence DRRs and their possible mechanisms were investigated. DRRs were recorded in anesthetized rats from filaments teased from the cut central stump of the left L(4) or L(5) dorsal root, using a monopolar recording electrode. Stimulating electrodes were placed either on the left sciatic nerve or transcutaneously in the left foot. Animals were paralyzed and maintained by artificial ventilation. Drugs were applied topically to the spinal cord. A total of 64 units were recorded in 34 Sprague-Dawley rats. Peripheral receptive fields were found for nine of these units. In these units, DRRs were evoked by brush, pressure, and pinch stimuli. Nine units were tested for an effect of electrical stimulation in the periaqueductal gray on the DRRs. In eight cases, DRR responses were enhanced following PAG stimulation. The background activity was 4.2 +/- 1.9 spikes/s (mean +/- SE; range: 0-97.7; n = 57). The responses to agents applied to the spinal cord were (in spikes/s): artificial cerebrospinal fluid, 7.1 +/- 3.6 (range: 0-86.9; n = 25); 0.1 mM GABA, 16.8 +/- 8.7 (range: 0-191.0; n = 22); 1.0 mM GABA, 116.0 +/- 26.5 (range: 0.05-1001.2; n = 50); and 1.0 mM phenylbiguanide (PBG), 68.1 +/- 25.3 (range: 0-1,073.0; n = 49). Bicuculline (0.5 mM, n = 27) and ondansetron (1.0 mM, n = 10) blocked the GABA and PBG effects, respectively (P < 0.05). Significant cross blockade was also observed. It is concluded that GABA(A) receptors are likely to play a key role in the generation of DRRs, but that 5-HT(3) receptors may also contribute. DRRs can be modulated by supraspinal mechanisms through descending systems.

Capsaicin responses in heat-sensitive and heat-insensitive A-fiber nociceptors

The recently cloned vanilloid receptor (VR1) is postulated to account for heat and capsaicin sensitivity in unmyelinated afferents. We sought to determine whether heat and capsaicin sensitivity also coexist in myelinated nociceptive afferents. Action potential (AP) activity was recorded from single A-fiber nociceptors that innervated the hairy skin in monkey. Before intradermal injection of capsaicin (10 microg/10 microl) into the receptive field, nociceptors were classified as heat-sensitive (threshold, </=53 degrees C, 1 sec) or heat-insensitive afferents and as mechanically sensitive (von Frey threshold, <6 bar) or mechanically insensitive afferents. All heat-sensitive afferents (n = 16) were insensitive to mechanical stimuli but responded to the intradermal injection of capsaicin (69 +/- 7 APs in 10 min). Responsiveness to mechanical stimuli, thermal stimuli, and capsaicin varied in their receptive fields; the majority of receptive field sites (24 of 36) were responsive to only one or two stimulus modalities, whereas only eight sites responded to all three modalities. For most heat-insensitive afferents, the activity induced by the capsaicin injection did not exceed the activity induced by needle insertion alone. However, the largest response to capsaicin (314 +/- 98 APs in 10 min) was observed for five afferents that were insensitive to heat as well as mechanical stimuli and therefore may be classified as cutaneous chemoreceptors. These results suggest that A-fiber nociceptors play a role in the pain and hyperalgesia associated with capsaicin injection. Our finding that a subgroup of capsaicin-sensitive A-fiber nociceptors are insensitive to heat predicts the existence of heat-insensitive capsaicin receptors.

Altered nociceptive neuronal circuits after neonatal peripheral inflammation

Nociceptive neuronal circuits are formed during embryonic and postnatal times when painful stimuli are normally absent or limited. Today, medical procedures for neonates with health risks can involve tissue injury and pain for which the long-term effects are unknown. To investigate the impact of neonatal tissue injury and pain on development of nociceptive neuronal circuitry, we used an animal model of persistent hind paw peripheral inflammation. We found that, as adults, these animals exhibited spinal neuronal circuits with increased input and segmental changes in nociceptive primary afferent axons and altered responses to sensory stimulation.

Electrophysiological assessment of the cutaneous arborization of Adelta-fiber nociceptors

Little is known about the relationship between the branching structure and function of physiologically identified cutaneous nociceptor terminals. The axonal arborization itself, however, has an impact on the afferent signal that is conveyed along the parent axon to the CNS. We therefore developed electrophysiological techniques to investigate the branching structure of cutaneous nociceptors. Single-fiber recordings were obtained from physiologically identified nociceptors that innervated the hairy skin of the monkey. Electrodes for transcutaneous stimulation were fixed at two separate locations inside the receptive field. For 32 Adelta-fiber nociceptors, distinct steps in latency of the recorded action potential were observed as the intensity of the transcutaneous electrical stimulus increased, indicating discrete sites for action potential initiation. The number of discrete latencies at each stimulation location ranged from 1 to 9 (3.7 +/- 0. 2; mean +/- SE) and the mean size of the latency step was 9.9 +/- 1. 0 ms (range: 0.4-89.1 ms). For seven Adelta fibers, collision techniques were used to locate the position of the branch point where the daughter fibers that innervated the two locations within the receptive field join the parent axon. To correct for changes in electrical excitability at the peripheral terminals, collision experiments between the two skin locations and between each skin location and a nerve trunk electrode were necessary. Nine branch points were studied in the seven Adelta fibers; the mean propagation time from the action potential initiation site to the branch point was 31 +/- 5 ms corresponding to a distance of 54 +/- 10 mm. Almost half of the daughter branches were unmyelinated. These results demonstrate that collision techniques can be used to study the functional anatomy of physiologically identified nociceptive afferent terminals. Furthermore these results indicate that some nociceptive afferents branch quite proximal to their peripheral receptive field. Occlusion of action potential activity can occur in these long branches such that the shorter branches dominate in the response to natural stimuli.

Nitric oxide mediates the central sensitization of primate spinothalamic tract neurons

Nitric oxide (NO) has been proposed to contribute to the development of hyperalgesia by activating the NO/guanosine 3',5'-cyclic monophosphate (cGMP) signal transduction pathway in the spinal cord. We have examined the effects of NO on the responses of primate spinothalamic tract (STT) neurons to peripheral cutaneous stimuli and on the sensitization of STT cells following intradermal injection of capsaicin. The NO level within the spinal dorsal horn was increased by microdialysis of a NO donor, 3-morpholinosydnonimine (SIN-1). SIN-1 enhanced the responses of STT cells to both weak and strong mechanical stimulation of the skin. This effect was preferentially on deep wide dynamic range STT neurons. The responses of none of the neurons tested to noxious heat stimuli were significantly changed when SIN-1 was administered. Intradermal injection of capsaicin increased dramatically the content of NO metabolites, NO-2/NO-3, within the dorsal horn. This effect was attenuated by pretreatment of the spinal cord with a nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine methyl ester (L-NAME). Sensitization of STT cells induced by intradermal injection of capsaicin was also prevented by pretreatment of the dorsal horn with the NOS inhibitors, L-NAME or 7-nitroindazole. Blockade of NOS did not significantly affect the responses of STT cells to peripheral stimulation in the absence of capsaicin injection. The data suggest that NO contributes to the development and maintenance of central sensitization of STT cells and the resultant mechanical hyperalgesia and allodynia after peripheral tissue damage or inflammation. NO seems to play little role in signaling peripheral stimuli under physiological conditions.

Nitric oxide-mediated spinal disinhibition contributes to the sensitization of primate spinothalamic tract neurons

This study concentrated on whether an increase in spinal nitric oxide (NO) diminishes inhibition of spinothalamic tract (STT) cells induced by activating the periaqueductal gray (PAG) or spinal glycinergic and GABAergic receptors, thus contributing to the sensitization of STT neurons. A reduction in inhibition of the responses to cutaneous mechanical stimuli induced by PAG stimulation was seen in wide dynamic range (WDR) STT cells located in the deep layers of the dorsal horn when these neurons were sensitized during administration of a NO donor, 3-morpholinosydnonimine (SIN-1), into the dorsal horn by microdialysis. In contrast, PAG-induced inhibition of the responses of high-threshold (HT) and superficial WDR STT cells was not significantly changed by spinal infusion of SIN-1. A reduction in PAG inhibition when STT cells were sensitized after intradermal injection of capsaicin could be nearly completely blocked by pretreatment of the dorsal horn with a NO synthase inhibitor, 7-nitroindazole. Moreover, spinal inhibition of nociceptive activity of deep WDR STT neurons elicited by iontophoretic release of glycine and GABA agonists was attenuated by administration of SIN-1. This change paralleled the change in PAG-induced inhibition. However, the inhibition of HT and superficial WDR cells induced by glycine and GABA release did not show a significant change when SIN-1 was administered spinally. Combined with our recent results, these data show that the effectiveness of spinal inhibition can be reduced by the NO/cGMP pathway. Thus disinhibition may constitute one mechanism underlying central sensitization.

Inhibition of primate spinothalamic tract neurons by spinal glycine and GABA is modulated by guanosine 3',5'-cyclic monophosphate

Our recent work has suggested that the nitric oxide/guanosine 3', 5'-cyclic monophosphate (NO/cGMP) signal transduction system contributes to central sensitization of spinothalamic tract (STT) neurons in part by influencing the descending inhibition of nociception resulting from stimulation in the periaqueductal gray. This study was designed to examine further whether activation of the NO/cGMP cascade reduces the inhibition of the activity of STT neurons mediated by spinal inhibitory amino acid (IAA) receptors. Responses of STT cells to noxious cutaneous stimuli were inhibited by iontophoresis of glycine and GABA agonists in anesthetized monkeys. Administration of 8-bromoguanosine-3',5'-cyclophosphate sodium (8-bromo-cGMP), a membrane permeable analogue of cGMP, either by microdialysis or by iontophoresis reduced significantly the IAA-induced inhibition of wide dynamic range (WDR) STT cells in the deep layers of the dorsal horn. The reduction in inhibition lasted for up to 1-1.5 h after the cessation of drug infusion. In contrast, IAA-induced inhibition of WDR STT cells in the superficial dorsal horn and high-threshold (HT) cells in superficial or deep layers was not significantly changed during 8-bromo-cGMP infusion. Iontophoresis of 8-bromo-cGMP onto STT cells produced the same actions as produced by microdialysis of this agent, but the effect was not as long-lasting nor as potent. Finally, an attenuation of the IAA receptor-mediated inhibition of STT cells produced by iontophoretic release of a NO donor, 3-morpholinosydnonimine, could be blocked by pretreatment of the spinal cord with a guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. These results suggest that an increased spinal cGMP level contributes to the sensitization of WDR STT neurons in the deep dorsal horn in part by down-regulating spinal IAA receptors. However, no evidence is provided in this study that the NO/cGMP cascade regulates IAA receptors on HT and superficial WDR neurons. Combined with the preceding studies, our data support the view that NO and cGMP function in the same signal transduction cascade and play an important role in central sensitization.

Polycaprolactone/glass bioabsorbable implant in a rabbit humerus fracture model

Research in improved materials and methods for internal fixation has centered on internal fixators made of bioabsorbable materials such as polylactic acid, polyglycolic acid, and polyparadioxanone. These materials have two problems: the first is a postoperative complication related to a delayed inflammatory response; and the second is low strength characteristics. An alternative material developed to alleviate these problems is a composite of phosphate glass fibers embedded in the polymer polycaprolactone, referred to as PCL. In this study, intramedullary pins made of PCL were compared to stainless steel pins in a rabbit humerus osteotomy model. Specimens were harvested at 0, 6, and 12 weeks postoperatively, radiographs and mechanical testing to failure were performed at each time interval, and tissue was examined microscopically at 6 and 12 weeks. Histologic results showed PCL pins to be well tolerated with minimal inflammation around the pin. Mechanical testing revealed the PCL fixation to be weaker initially than the stainless steel fixation. There was significant stress shielding of stainless-steel-healed rabbit humeri when compared to the PCL/bone humeri. All osteotomies immobilized with PCL healed with abundant periosteal callus production.

Involvement of protein kinase C in responses of rat dorsal horn neurons to mechanical stimuli and periaqueductal gray descending inhibition

The effects of a protein kinase C (PKC) activator, 12-O-tetradecanoylphorbol-13-acetate (TPA), on the activity and periaqueductal gray (PAG)-induced inhibition of rat dorsal horn neurons of the lumbar spinal cord were tested. A microdialysis fiber was placed through the dorsal horn for the purpose of local application of pharmacological agents. Extracellular single-unit recordings from dorsal horn neurons were made near the microdialysis fiber. TPA was tested on nociceptive dorsal horn cells. There was a significant increase in the background activity and responses to "brush", with no changes in responses to pressure and pinch stimuli. TPA also significantly blocked the PAG-induced inhibition of responses to brush, press, and pinch. These effects were eliminated by coadministration of the PKC inhibitor NPC-15437. The solvent, which contained dimethyl sulfoxide, was also tested for its effect on the responses to peripheral mechanical stimuli and PAG-induced inhibition of the dorsal horn neurons. There were no significant changes. This experiment suggests that activation of the PKC second messenger system might increase the activity of dorsal horn neurons and their responses to peripheral stimuli; in addition, the phorbol ester attenuated the PAG-induced descending inhibition of the dorsal horn neuron activity.

Involvement of cGMP in nociceptive processing by and sensitization of spinothalamic neurons in primates

Central sensitization of spinothalamic tract (STT) neurons in anesthetized monkeys after intradermal injection of capsaicin depends in part on disinhibition. Protein kinase C is suggested to participate in this process. The present study shows that the nitric oxide-cGMP (NO-cGMP) signal transduction system also contributes to sensitization of wide dynamic range (WDR) STT neurons located in the deep dorsal horn. The NO-cGMP system was activated by microdialysis administration into the dorsal horn of 8-bromo-cGMP, an analog of cGMP. Sensitization of STT cells by 8-bromo-cGMP increased the responses of deep WDR STT cells to both weak and strong mechanical stimulation of the skin and simultaneously attenuated the inhibition of the same neurons produced by stimulation in the periaqueductal gray (PAG). In contrast, WDR STT cells in the superficial dorsal horn and high-threshold (HT) STT cells in superficial or deep layers showed reduced responses to mechanical stimulation of the skin after infusion of 8-bromo-cGMP, and PAG inhibition of these neurons was unaffected. Sensitization of STT cells and the attenuation of PAG inhibition induced by intradermal injection of capsaicin were prevented by preteatment of the dorsal horn with a guanylate cyclase inhibitor, 1 H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. The results support the hypothesis that activation of the NO-cGMP signal transduction system contributes to the sensitization of WDR STT neurons in the deep dorsal horn and helps explain why intradermal capsaicin injections often fail to sensitize superficial and HT STT cells. The results also support the idea that sensitization of STT cells is produced in part by disinhibition.

Effects of GABA and glycine receptor antagonists on the activity and PAG-induced inhibition of rat dorsal horn neurons

The effects of bicuculline and strychnine on the activity and periaqueductal gray (PAG)-induced inhibition of rat dorsal horn neurons of the lumbar spinal cord were tested. Extracellular single unit recordings were from 36 dorsal horn neurons near a microdialysis fiber passed through the spinal cord for drug application. The GABAA receptor antagonist, bicuculline, was tested on 19 cells, whereas the glycine receptor antagonist, strychnine, was tested on 17 cells. Both bicuculline and strychnine increased the background activity and responses to mechanical stimulation (BRUSH, PRESS, and PINCH) of the skin.06 They also significantly blocked the PAG-induced inhibition of responses to peripheral mechanical stimuli. This experiment suggests that the mechanism of PAG-induced descending inhibition of dorsal horn neuron activity involves GABA and/or glycine release in the spinal cord and that there is tonic release of these inhibitory neurotransmitters.

Inhibition of primate spinothalamic tract neurons by spinal glycine and GABA is reduced during central sensitization

1. In our previous work, we demonstrated that the glycinergic and GABAergic mechanisms that help mediate the descending inhibition from the periaqueductal gray exert a tonic modulation of nociceptive inputs through spinal glycine and gamma-aminobutyric acid (GABA) receptors. This study was designed to examine further possible changes in the inhibition of the activity of spinothalamic tract (STT) neurons mediated by spinal glycine and GABA receptors when STT cells are sensitized by intradermal injection of capsaicin, and to investigate the role of the protein kinase C (PKC) system in the functional modulation of these receptors. 2. Although the responses of STT cells to cutaneous mechanical stimuli were sensitized by intradermal injection of capsaicin, the inhibition of the responses of all STT cells tested to noxious cutaneous stimuli produced by iontophoretic release of glycine and GABA was significantly attenuated. The inhibition elicited by iontophoretic application of a GABAA agonist, muscimol, was reduced in some of the cells tested. 3. When the spinal cord dorsal horn was pretreated with a selective PKC inhibitor, 2,6-diamino-N-([1-oxotridecyl-2-piperidinyl]- methyl)hexanamide, by microdialysis, sensitization of STT cells by capsaicin injection and the accompanying attenuation of glycine- and GABA-induced inhibition were prevented. 4. Sensitization of STT cells to cutaneous mechanical stimuli was also induced by administration of the PKC activator, 12-O-tetradecanoylphorbol-13-acetate, into the spinal dorsal horn. The inhibition produced by iontophoretic release of glycine, GABA, and muscimol was found to be reduced in most cells examined when this phorbol ester was used. An inactive phorbol ester, 4 alpha-phorbol 12,13-didecanoate, did not produce significant effects on cellular activity. 5. These results suggest that there is an activation of PKC in the spinal cord when STT neurons are sensitized after intradermal injection of capsaicin or administration of phorbol ester. This sensitization is likely to be involved in the development of allodynia and secondary hyperalgesia not only by enhancing the responses of excitatory amino acid receptors but also by desensitizing glycine and GABA receptors.

Involvement of alpha-2 adrenoceptors in the periaqueductal gray-induced inhibition of dorsal horn cell activity in rats

The noradrenergic system is considered to be one of the major descending analgesia systems originating in the brainstem. The relationship between the periaqueductal gray (PAG) and the descending noradrenergic system is of great interest. A projection from the PAG to the locus ceruleus and parabrachial region has been reported. It is possible that electrical stimulation of the PAG activates spinally projecting collaterals of the noradrenergic cells in A5, the locus ceruleus, subceruleus and A7/Kölliker-Fuse nucleus. The current experiments were designed to study the role of alpha-2 adrenoceptors on spinal cord dorsal Horn cells in PAG-induced inhibition. A microdialysis fiber was introduced into the dorsal horn of the lumbar enlargement for drug administration. An electrode was placed in the vicinity of the microdialysis fiber for extracellular single-unit recording. Recordings were made from a total of 35 cells from 22 Sprague-Dawley rats (270-360 g). When the PAG was stimulated, responses to mechanical stimuli applied to the skin (brush, press and pinch) were inhibited. When an alpha-2 adrenoceptor agonist (clonidine) was administered, the background activity and the responses of the cell to brush, press and pinch stimuli were decreased. In contrast, administration of alpha-2 adrenoceptor antagonists (idazoxan or yohimbine) increased the responses of the cell to brush, press and pinch stimuli. The background activity was also increased by idazoxan. The PAG-induced inhibition of the response to mechanical stimuli was reduced by idazoxan and yohimbine. These results suggest an involvement of alpha-2 adrenoceptors in the mechanism of PAG-induced inhibition of dorsal horn cell activity.

Possible role of protein kinase C in the sensitization of primate spinothalamic tract neurons

The responsiveness of spinal cord nociceptive neurons to innocuous mechanical stimuli can be increased by the release of excitatory amino acids (EAAs) and peptides attributable to an injury-induced barrage of impulses. This sensitization of spinal dorsal horn neurons can also result from administration of phorbol ester by microdialysis, presumably by direct activation of protein kinase C (PKC). This study was designed to examine the effects of central sensitization of spinothalamic tract (STT) neurons produced by intradermal injection of capsaicin on the descending inhibition driven from the periaqueductal gray (PAG) and the possible role of PKC in this process in anesthetized monkeys. Sensitization of responses of STT cells to mechanical stimuli was induced by intradermal injection of capsaicin. PAG inhibition was significantly attenuated when sensitization of responses to mechanical stimuli occurred. However, perfusion of the spinal cord with NPC15437 (a selective PKC inhibitor) by microdialysis could prevent the sensitization of the responses to mechanical stimuli and the reduction in PAG inhibition of these responses induced by capsaicin injection. Results similar to those produced by capsaicin injection were observed when a PKC activator, phorbol ester (12-O-tetradecanoylphorbol-13-acetate), was infused within the dorsal horn by microdialysis. An inactive phorbol ester (4 alpha-phorbol 12,13-didecanoate) had no effect. These results provide evidence that the activation of PKC contributes to the development of central sensitization in dorsal horn neurons produced by chemical stimulation with capsaicin. Attenuation of the effectiveness of PAG inhibition takes place when the sensitization of dorsal horn cells develops, and PKC may play a significant role in this process.

Antinociception and inhibition from the periaqueductal gray are mediated in part by spinal 5-hydroxytryptamine(1A) receptors

Although 5-hydroxytryptamine (5-HT) is known to be involved in the mediation of antinociception from the periaqueductal gray (PAG), its mode of action remains obscure. This investigation uses selective 5-HT(1A) receptor agonist and antagonist drugs in both behavioral and electrophysiological studies on antinociceptive mechanisms of the PAG of rats. Intraspinal administration of 8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT), a selective 5-HT(1A) agonist, by microdialysis produced a dose-dependent antinociception in the radiant-heat paw withdrawal test. Dorsal horn neuronal activity was recorded extracellularly to test responses to noxious cutaneous stimuli when 8-OH-DPAT was administered iontophoretically, and it was observed that the noxious-evoked responses were inhibited in a current-related manner in all cells examined. The inhibitory effects elicited by 8-OH-DPAT could be selectively blocked by perfusion of the spinal cord with S-(--)-propranolol, a selective 5-HT(1A) antagonist. The antinociception produced by microinjection of morphine into the PAG was significantly attenuated in a dose-related manner by S-(--)-propranolol administered into the spinal cord. Similarly, the inhibition of dorsal horn neuronal responses to cutaneous mechanical stimuli produced by electrical stimulation in the PAG was reduced by S-(--)-propranolol administered into the spinal cord in the majority of cells tested. These data suggest that the release of 5-HT in the dorsal horn by stimulation in the PAG may act directly on spinal 5-HT(1A) receptors, resulting in inhibition of dorsal horn neurons. This is presumably one of the antinociceptive mechanisms of the descending serotonergic inhibitory pathway.

Role of GABA receptor subtypes in inhibition of primate spinothalamic tract neurons: difference between spinal and periaqueductal gray inhibition

1. gamma-Aminobutyric acid (GABA) is thought to inhibit both pre- and postsynaptically the transfer of nociceptive signals from primary afferent fibers to spinal dorsal horn sensory cells, including spinothalamic tract (STT) neurons. The inhibition can be mediated by both GABAA and GABAB receptors. We now attempt to characterize the synaptic inhibition of STT cells by spinal GABAA and GABAB receptors in anesthetized monkeys and to analyze the roles of these two receptor subtypes in the inhibition of STT cellular activity produced by stimulation in the periaqueductal gray (PAG). 2. Iontophoretic release of GABA or muscimol (a selective GABAA receptor agonist) onto STT cells elicited a profound and dose-related inhibition of the responses of all cells tested to noxious cutaneous stimuli. Only four cells (16.7%) were found to be inhibited when baclofen (a selective GABAB receptor agonist) was applied iontophoretically. However, a strong and dose-dependent inhibition of the responses to cutaneous mechanical and thermal stimuli was obtained in all cells examined when baclofen was administered into the dorsal horn through a microdialysis fiber. The inhibitory effects were mainly on nociceptive inputs. 3. The inhibition of cellular activity by GABAA and GABAB agonists could be selectively antagonized by specific antagonists applied through a microdialysis fiber. 4. The excitatory responses evoked by pulsed release of glutamic acid (GLUT) were also inhibited in a dose-related manner by iontophoretic application of GABA and muscimol, but not by baclofen. A high dose of baclofen administered by microdialysis resulted in only a small decrease in GLUT-evoked excitatory responses. 5. Infusion of GABAA and GABAB antagonists into the dorsal horn by microdialysis caused an increase in both background activity and responses to cutaneous stimuli, suggesting that there is a tonic GABAergic inhibition of STT cells. 6. The inhibition of responses to mechanical and thermal stimulation of the cutaneous excitatory receptive field resulting from stimulation in PAG was significantly antagonized in most of the STT cells tested when the GABAA antagonist bicuculline was infused into the spinal dorsal horn through a microdialysis fiber. In contrast, the inhibition produced by PAG stimulation in most of the cells examined was not significantly antagonized by the GABAB antagonists phaclofen or 3-amino-propyl(diethoxymethyl)phophinic acid (CGP35348) administered into the spinal dorsal horn by microdialysis. 7. Our results support the contention that GABAergic mechanisms in the spinal dorsal horn normally exert a tonic modulation of nociceptive inputs through both GABAA and GABAB receptors. The evidence provided here indicates that GABAA receptors located on primate STT neurons contribute to a postsynaptic inhibitory effect on the transmission of peripheral nociceptive inputs. A possible presynaptic GABAA action was not investigated. Our finding of a GABAB-receptor-mediated inhibition is consistent with the view that both pre- and postsynaptic GABAB receptors are involved in inhibitory modulation of spinal nociceptive transmission. Finally, it is suggested from this study that primate spinal GABAA, but not GABAB receptors, are involved in mediating the descending inhibition induced by PAG stimulation.

The role of 5-HT3 receptors in periaqueductal gray-induced inhibition of nociceptive dorsal horn neurons in rats

Electrical stimulation in the periaqueductal gray (PAG) can inhibit dorsal horn cell responses to both innocuous and noxious cutaneous stimuli. This inhibition is believed to be due to the release of serotonin (5-HT) into the dorsal horn of the spinal cord from descending axons of the nucleus raphe magnus and the adjacent reticular formation. It is still not clearly known which subtypes of 5-HT receptors are involved in the PAG-induced inhibition. Extracellular single-unit recordings of dorsal horn cell activity, in combination with drug administration through a microdialysis fiber, were used to test the role of 5-HT3 receptors in PAG-induced inhibition. The responses of the cells to mechanical stimulation of the skin (BRUSH, PRESS and PINCH) and to the same stimuli while stimulating PAG were recorded. When the 5-HT3 antagonist, ondansetron, was perfused through the microdialysis fiber, not only was the background activity of the cell increased, but also the responses to BRUSH, PRESS and PINCH stimuli. The PAG-induced inhibition of responses to the same stimuli was partially or completely blocked by ondansetron. Another 5-HT3 antagonist, zacopride, did not increase the background activity or responses to PRESS and PINCH, yet this agent, like ondansetron, blocked PAG inhibition. The 5-HT3 agonist, phenylbiguanide, inhibited the background activity and the responses to mechanical stimuli. These results suggest that 5-HT released in the dorsal horn by stimulation in the PAG excites inhibitory interneurons through 5-HT3 receptors, resulting in inhibition of dorsal horn neurons.

Acetyl-L-carnitine arginyl amide (ST857) increases calcium channel density in rat pheochromocytoma (PC12) cells

We used the patch clamp technique to study the effect of acetyl-L-carnitine arginyl amide (ALCAA) and of nerve growth factor (NGF) on availability of L-type Ca2+ channels in rat pheochromocytoma (PC12) cells maintained in defined medium. Channel availability was measured as number of channels in the patch x the probability of opening (n.Po). In patches from control cells, cells exposed to NGF (10 ng/ml) for six days, and cells exposed to ALCAA (1 mM) for six days, n.Po, measured during 200-240 ms pulses to -10 mV (holding potential, -60 mV), was 0.102 +/- 0.089 (5 cells), 0.173 +/- 0.083 (5 cells), and 0.443 +/- 0.261 (7 cells), respectively. The 4.3-fold increase for the ALCAA-treated cells was significantly different from control (P < 0.05), whereas that for the NGF-treated cells was not. For the same conditions, the maximum number of superimposed openings at -10 mV was 1.3 +/- 0.5 (6 cells), 1.6 +/- 0.5 (8 cells), and 3.3 +/- 1.8 (8 cells), with the value for the ALCAA-treated cells being significantly different from control (P < 0.001). Additional analysis showed that the distribution of channel open times, the time constants, and the voltage dependence of activation were not changed by prolonged exposure to ALCAA. Short-term exposure to both ALCAA as well as to the parent compound, acetyl-L-carnitine (ALCAR), did not cause an increase but rather a decrease in n.Po, and this short-term effect of both compounds was blocked by neomycin, an inhibitor of phospholipase C.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunization strategies for the production of rat monoclonal anti-idiotope antibodies

Anti-idiotypic antibodies are powerful reagents for the study of immunoregulation, and have potential interest as vaccines against tumors and infectious diseases. Three immunization strategies for the production of rat monoclonal anti-idiotope antibodies have been compared in this paper. Male Wistar rats were immunized i.p. and at multiple subcutaneous sites with 750 micrograms of purified monoclonal antibody against Plasmodium falciparum for three times and subsequently boosted by (1) intraperitoneal injection with 750 micrograms of the immunogen, (2) intravenous inoculation with 400 micrograms of the IgG, and (3) intrasplenic immunization with 200 micrograms of the idiotype. With the intraperitoneal boost method, the frequency of hybrids with anti-idiotope activity was 0.3-0.9% with 62.8-85.2% of the seeded wells containing hybrids. In the intravenous boost group, the percentage of hybrids demonstrating anti-idiotope activity increased to 11.0-13.3% with 80.2-97.9% of the hybrid efficiency. When immunized by the intrasplenic boost route, the frequency of anti-idiotope hybrids generated rose to 12.9-16.4% with 82.3-96.6% of the hybrid efficiency. There was no obvious effect of the boost immunizing methods on the generation of rat monoclonal anti-mouse IgG antibodies. These results indicated that the multiple-site immunization followed by intravenous or intrasplenic boost injection was an appropriate immunizing method for the production of monoclonal anti-idiotope antibodies.

Omental autotransplantation in treatment of thromboangiitis obliterans

From 1981 to 1985, omental autotransplantation was performed for 28 patients with thromboangiitis obliterans on the left lower extremities in 16 patients, the right ones 11, and the right upper limb 1. The early results in all patients were satisfactory. In 19 patients followed up from 1 to 4 years, the results were encouraging, with the improvement of symptoms after operation. In 18 patients, digital ulcers healed within 2-4 weeks. Doppler and electrical impedance plethysmography examinations showed the blood circulation of affected extremities was markedly improved in the 18 patients except one who had the recurrence of digital ulcer 2 years later. In one of the 19 patients the disease recurred one month after the operation, and a lumbar sympathectomy was performed. The indications, the operative technique, and the mechanism of this operation are discussed.