[Preparation of renal cancer vaccine of IL-12-anchored exosomes and its antitumor effect in vitro]

OBJECTIVE

To prepare a vaccine of IL-12-anchored exosomes derived from renal cancer cells and to evaluate its antitumor effect in vitro.

METHODS

A mammalian co-expression plasmid of glycolipid-anchor-IL-12 (GPI-IL-12) was constructed by subcloning IL-12A chain gene (P35 subunit) and a fusion gene containing GPI-anchor signal sequence and IL-12B chain gene (P40 subunit) in pBudCE4.1. Confocal laser scanning microscopy and flow cytometry were used to analyze the expression of the fusion proteins. Transmission electron microscopy and Western blot were used to identify the morphology and characteristic molecules of exosomes separated by ultrafiltration and sucrose gradient centrifugation. The function of IL-12-anchored exosomes was determined by IFN-gamma release assay.

RESULTS

Mammalian co-expression plasmids were successfully constructed. Confocal laser scanning microscopy and flow cytometric analysis of the RC-2-GPI-IL-12 transfectants showed the expression of IL-12 on the cell surface. Exosomes were purified by ultrafiltration and sucrose gradient centrifugation, which were 30-80 nm in diameter, typically saucer-shaped, and expressing HSP70, ICAM-1, G250 and GPI-IL-12. (80.0 +/- 9.6) pg/ml of IL-12 was detected in 10 microg/ml exosomes and it significantly induced the release of IFN-gamma. Stimulation with EXO-IL-12 could efficiently induce antigen-specific cytotoxic T lymphocytes (CTL), resulting in more significant cytotoxic effects in vitro.

CONCLUSION

A vaccine of exosomes-GPI-IL-12 can be obtained from the culture supernatant of renal cancer cells modified to express anchored IL-12. This vaccine expressing IL-12 and tumor associated antigen G250 may become a new strategy for the treatment of renal cancer.

Effects of neonatal flutamide treatment on hippocampal neurogenesis and synaptogenesis correlate with depression-like behaviors in preadolescent male rats

The prevalence of major depressive disorder (MDD) in adult men is roughly half that of women. Clinical evidence supports a protective effect of androgens against depressive disorders in men. The developing brain is subject to androgen exposure but a potential role for this in depression during adulthood has not been considered. In order to explore this question we treated newborn male rat pups with the androgen receptor antagonist flutamide to block endogenous androgen action and then conducted behavioral tests prior to puberty. Depression-like behaviors were assessed with the Forced Swim Test (FST) and the Sucrose Preference Test (SPT), and anxiety-like behaviors were assessed with the Open Field Test (OFT) and the Novelty-Suppressed Feeding Test (NSFT). Compared to the vehicle-treated controls, neonatal-flutamide treatment caused a significant increase in depression-like behaviors in preadolescent male rats but did not cause any significant difference in anxiety-like behaviors. In separate experiments, male pups with and without flutamide treatment were injected with 5-bromo-2'-deoxyuridine-5'-monophosphate (BrdU) from postnatal day (PND) 1 to 4 to label newly produced cells or the hippocampi were Golgi-Cox imbedded and pyramidal neurons visualized. Three lines of evidence indicate neonatal flutamide treatment inhibits hippocampal neurogenesis and neuronal dendritic spine formation in preadolescent male rats. Compared to vehicle controls, flutamide treatment significantly decreased (1) the number of microtubule-associated protein-2+ (MAP-2) neurons in the CA1 region, (2) the number of MAP-2+ neurons in the dentate gyrus (DG) region of the hippocampus, and (3) the density of dendritic spines of pyramidal neurons in the CA1 region. However, there was no effect of flutamide treatment on the number of glial fibrillary acidic protein (GFAP)+ or GFAP+/BrdU+ cells in the hippocampus. This study suggests that the organizational effect of androgen-induced hippocampal neurogenesis is antidepressant.

Effects of annealing on the ferromagnetism and photoluminescence of Cu-doped ZnO nanowires

Room temperature ferromagnetic Cu-doped ZnO nanowires have been synthesized using the chemical vapor deposition method. By combining structural characterizations and comparative annealing experiments, it has been found that both extrinsic (CuO nanoparticles) and intrinsic (Zn(1-x)Cu(x)O nanowires) sources are responsible for the observed ferromagnetic ordering of the as-grown samples. As regards the former, annealing in Zn vapor led to a dramatic decrease of the ferromagnetism. For the latter, a reversible switching of the ferromagnetism was observed with sequential annealings in Zn vapor and oxygen ambience respectively, which agreed well with previous reports for Cu-doped ZnO films. In addition, we have for the first time observed low temperature photoluminescence changed with magnetic properties upon annealing in different conditions, which revealed the crucial role played by interstitial zinc in directly mediating high T(c) ferromagnetism and indirectly modulating the Cu-related structured green emission via different charge transfer transitions.

[Effects of silencing transforming growth factor-beta1 by RNAi upon transdifferentiation of renal allograft tubular epithelial cells in rats]

OBJECTIVE

To investigate the effects of shRNA-transforming growth factor (TGF)-beta1 plasmid upon epithelial-myofibroblast transdifferentiation of renal allograft in rats.

METHODS

Divided the Wistar rats into 4 groups: Group J (sham-operated group), T (plasmid group), H (vacant plasmid group) and Y (simply transplantation group). The SD to Wistar rat transplant kidney-sclerosis accelerated model was constructed and transfected with the plasmid based on hydromechanics. Transplanted kidneys were collected at Months 1, 2 and 3 post-transplantation. The gene transcriptional levels of TGF-beta1 and E-cadherin were detected by RT-PCR and the protein variation of E-cadherin was examined by Western blotting. The pathological changes and infiltrated inflammatory cells were assessed by HE staining and the immunohistochemical staining of E-cadherin and alpha-SMA used to label epithelial cells and fibroblast in order to exhibit cell transdifferentiation.

RESULTS

Compared with Group H and Y, the mRNA transcription of TGF-beta1 was obviously inhibited in the Group T: at Month 3, the TGF-beta1 mRNA of Group T is 0.73 +/- 0.08, significantly lower than Group H and Y (0.92 +/- 0.07 and 0.95 +/- 0.04, both P < 0.01); the expression of E-cadherin was maintained at a high level: at the Month 3, the E-cadherin mRNA of Group T is 0.39 +/- 0.11, significantly higher than Group H and Y (0.15 +/- 0.07, and 0.17 +/- 0.06, both P < 0.01); the E-cadherin protein of Group T is 0.38 +/- 0.08, significantly higher than group H and Y (0.15 +/- 0.07 and 0.15 +/- 0.07, both P < 0.01); epithelial cells were much more and fibroblast was much less than that of Group H and Y; there were also less infiltrated chronic inflammatory cells and extracellular matrix deposition in the Group T.

CONCLUSION

The shRNA-TGF-beta1 plasmid can inhibit the epithelial-myofibroblast transdifferentiation of renal allograft in rats. The mechanisms may be associated with its effects of down-regulating TGF-beta1 and up-regulating E-cadherin.

[Exosomes derived form bladder transitional cell carcinoma cells induce CTL cytotoxicity in vitro]

OBJECTIVE

To isolate and purify exosomes derived from human bladder transitional cell carcinoma T24 cells, analyze the morphology and protein composition, and investigate the antitumor effect of specific cytotoxic T lymphocytes induced by exosomes.

METHODS

Exosomes were isolated and purified by ultrafiltration and sucrose gradient centrifugation, and characterized by electron microscopy and Western blot. Dendritic cells were amplified and purified from peripheral blood and pulsed with exosomes. Then they were co-cultured with T cells, and divided into 3 groups: exosome-pulsed DC group, unplused DC group and control group. Alamar-Blue assay was used to evaluate the specific cytolytic activity.

RESULTS

The exosomes were in size about 30 approximately 90 nm saucer-shaped membranous vesicles. HSP70, ICAM-1 and CK20 were detected by Western blot. The CTL induced by DC pulsed with exosomes had significant cytolytic activity (P < 0.01).

CONCLUSION

The exosomes derived from T24 cells are loaded with immunoprotein HSP70 and ICAM-1, and DC pulsed with exosomes can promote the anti-tumor effect of CTLs in vitro.

Two new mutations in the keratin 4 gene causing oral white sponge nevus in Chinese family

OBJECTIVE

We investigated white sponge nevus (WSN) in a Chinese family, and tried to find new mutation and demonstrated that this mutation is the causative mutation for WSN in this family and this condition affects a functionally important segment of the keratin 4 protein.

MATERIALS AND METHODS

We studied the affected family with the 32-year-old female patient, her mother, her younger sister and her daughter. Pathologic examinations were performed. DNA was extracted from peripheral blood lymphocytes, K4 and K13 genes were amplified by polymerase chain reaction (PCR) and sequenced.

RESULTS

Direct sequencing of PCR products revealed two new mutations in the keratin 4 gene, the heterozygous missense mutation 1829G-->A in exon 2B, and 2324A-->G in non-coding region. No any mutation was found in the keratin 13 gene.

CONCLUSIONS

We found two new mutations in the keratin 4, which may be related with the development of WSN.

Troponin T measurement can predict persistent left ventricular dysfunction in peripartum cardiomyopathy

OBJECTIVE

To determine whether measurement of cardiac troponin T (cTnT) concentration in newly diagnosed peripartum cardiomyopathy (PPCM) can be used to predict persistent left ventricular dysfunction after a 6-month follow-up.

PATIENTS AND METHODS

This was a prospective, multiple-centre clinical trial that studied 106 patients with newly diagnosed PPCM surviving over 6 months. cTnT concentration was measured within 2 weeks of the onset of PPCM.

RESULTS

Serum cTnT concentration was negatively correlated with left ventricular ejection fraction (LVEF) at follow-up (LVEF, r = -0.518, p = 0.0001). Analysis by receiver operator characteristic curve yielded an area under the curve of 0.764 (95% CI 0.669 to 0.860, p = 0.0001, vs null hypothesis value 0.5) for cTnT, and a cTnT concentration cut off of >0.04 ng/ml, predicting persistent left ventricular dysfunction with a sensitivity of 54.9% and a specificity of 90.9%. Among 106 recruited patients, there were 33 patients with cTnT concentrations >0.04 ng/ml and 73 patients with cTnT concentrations < or =0.04 ng/ml. After a 6-month follow-up, there was significantly smaller LVEF (35.42% (13.04% vs 50.16% (10.48%, p = 0.0001) and more persistent left ventricular dysfunction (84.8% vs 31.5%, OR = 12.17 (95% CI 4.17 to 35.57), p = 0.001) in patients with cTnT >0.04 ng/ml than in patients with cTnT < or =0.04 ng/ml.

CONCLUSION

Serum cTnT concentration measured within 2 weeks of the onset of PPCM was correlated negatively with LVEF at follow-up. This marker offers a simple, quick, inexpensive, non-invasive method for predicting a persistent LVEF of < or =50%. A cTnT concentration of >0.04 ng/ml predicted persistent left ventricular dysfunction with a sensitivity of 54.9% and a specificity of 90.9%.

Genetic engineering of Periplaneta fuliginosa densovirus as an improved biopesticide

The smoky-brown cockroach (Periplaneta fuliginosa) densovirus (PfDNV) has previously shown potential in urban pest control. To improve its efficacy as a biopesticide, the genome of PfDNV was engineered by inserting the insect-specific toxin gene BmKIT1 in the open reading frame encoding the major structural proteins. A green fluorescent protein (GFP) marker was tagged to the BmKIT1 at its C-terminus for in vivo imaging using Confocal laser scanning microscopy (CFSM). Using a virion rescue strategy, the genomes of recombinant and wild-type (wt) PfDNV were then cotransfected in P. fuliginosa nymphs. Reverse transcription PCR (RT-PCR) showed that the inserted BmkIT1 genes were expressed in the P. fuliginosa nymphs 48 h after cotransfection. CFSM and transmission electron microscopy also confirmed the generation of virus particles and expression of BmKIT1-GFP fusion protein in the cotransfected nymphs. The recombinant viruses remained infective to P. fuliginosa nymphs in feeding tests. Using the LT(50) bioassay method, the coninfection of the recombinant and wt PfDNV killed the P. fuliginosa nymphs approximate 32% faster than wt PfDNV only. This is the first report showing the improvement of engineered densovirus for the potential application of biopesticide.

Observation of the decay psi(2S)-->K0SK0L

The decay psi(2S)-->K(0)(S)K(0)(L) is observed using psi(2S) data collected with the Beijing Spectrometer at the Beijing Electron-Positron Collider; the branching fraction is determined to be B(psi(2S)-->K(0)(S)K(0)(L))=(5.24+/-0.47+/-0.48)x10(-5). Compared with J/psi-->K(0)(S)K(0)(L), the psi(2S) branching fraction is enhanced relative to the prediction of the perturbative QCD "12%" rule. The result, together with the branching fractions of psi(2S) decays to other pseudoscalar meson pairs (pi(+)pi(-) and K+K-), is used to investigate the relative phase between the three-gluon and the one-photon annihilation amplitudes of psi(2S) decays.

Observation of a near-threshold enhancement in the pp mass spectrum from radiative J/psi-->gammapp decays

We observe a narrow enhancement near 2m(p) in the invariant mass spectrum of pp pairs from radiative J/psi-->gammapp decays. No similar structure is seen in J/psi-->pi(0)pp decays. The results are based on an analysis of a 58 x 10(6) event sample of J/psi decays accumulated with the BESII detector at the Beijing electron-positron collider. The enhancement can be fit with either an S- or P-wave Breit-Wigner resonance function. In the case of the S-wave fit, the peak mass is below 2m(p) at M=1859(+3)(-10) (stat)+5-25(syst) MeV/c(2) and the total width is Gamma<30 MeV/c(2) at the 90% confidence level. These mass and width values are not consistent with the properties of any known particle.

Huperzine A, a nootropic alkaloid, inhibits N-methyl-D-aspartate-induced current in rat dissociated hippocampal neurons

Huperzine A, a nootropic alkaloid isolated from a Chinese herb, has been proposed as one of the most promising agents to treat Alzheimer's disease. Recently, the agent was found to inhibit the N-methyl-D-aspartate (NMDA) receptors in rat cerebral cortex in addition to causing an inhibitory effect on acetylcholinesterase. In the present study, the mechanisms underlying NMDA receptor inhibition were investigated using whole-cell voltage-clamp recording in CA1 pyramidal neurons acutely dissociated from rat hippocampus. Huperzine A reversibly inhibited the NMDA-induced current (IC(50)=126 microM, Hill coefficient=0.92), whereas it had no effect on the current induced by alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate or kainate. The effect was non-competitive, and showed neither 'voltage-dependency', nor 'use-dependency'. The IC(50) values of huperzine A were neither altered by changing the concentrations of glycine (2-0.2 microM) and pH (7.4-6.7) in the external solution, nor by addition of Zn(2+) (5 microM) and dithiothreitol (5 mM) to the external solution. However, addition of spermine (200 microM) to the external solution caused a parallel shift to the right of the huperzine A concentration-response curve. From these we suggest that huperzine A acts as a non-competitive antagonist of the NMDA receptors, via a competitive interaction with one of the polyamine binding sites. The potential relevance of NMDA receptor antagonist activity of huperzine A to the treatment of Alzheimer's disease is discussed.

Mechanical hyperalgesia in rats with chronic perfusion of lumbar dorsal root ganglion with hyperglycemic solution

In diabetes, chronic systemic hyperglycemia is associated with pain and other symptoms of peripheral neuropathy. Evaluation of mechanisms causing these symptoms is complicated because of the overlap between the systemic effects of hyperglycemia and its toxic effects within the peripheral nervous system. To address this problem we developed a technique for chronic local in vivo perfusion of rat lumbar dorsal root ganglion (DRG) with a hyperglycemic solution. Osmotic pumps were filled with 30 mM glucose in physiological buffer and implanted in normal adult rats. The output of the catheter attached to the pump was positioned in a hole drilled through the right transverse process of the L(5) vertebrae to perfuse the corresponding DRG. Repetitive tests of foot withdrawal to mechanical stimuli have shown that chronic hyperglycemia localized to the L(5) DRG causes hyperalgesia in the hind limb innervated by perfused ganglion but not in the contralateral limb. Control experiments (DRG perfusion with 5 mM glucose or 5 mM glucose+25 mM mannitol solution) have shown that hyperglycemia-induced hyperalgesia can not be attributed to surgery-related injury or hyperosmolality of the ganglion-perfusing solution. These data demonstrate direct functional toxicity of hyperglycemia in the peripheral nervous system. This technique provides a new approach for in vivo study of chronic effects of physiologically active factors on DRG neuron function.

Topical application of acidic bupivacaine to the lumbar ganglion induces mechanical hyperalgesia in the rat

To investigate the neurologic mechanisms of acidic local anesthetic-induced low back pain in humans, we administered bupivacaine and buffered saline at acidic or alkalinized pH at the L5 dorsal root ganglion (DRG) of rats via a hole drilled through the transverse process covering the DRG. Behavioral changes were tested before and after bupivacaine or saline administration. Results indicate that acute single-dose infusion of the DRG with bupivacaine (0.5%) at acidic pH (5.5) induced ipsilateral mechanical hyperalgesia that lasted for 7 days. Acute infusion of alkalinized bupivacaine (pH 7.2), however, caused only minor hyperalgesia that lasted <3 days. Similar results were obtained when bupivacaine was replaced with saline. Alternatively, chronic delivery of acidic saline to the DRG via a subcutaneously implanted osmotic pump resulted in a significant decrease in the withdrawal threshold on the ipsilateral hind paw that lasted for 10 days. In rats receiving chronic treatment of the DRG with alkalinized saline, mechanical hyperalgesia lasted for only 3 days. The results demonstrated that acidic bupivacaine deposited at the DRG causes pain and hyperalgesia when the effects of the local anesthetic have dissipated. These findings may explain the limited therapeutic effects of some acidic local anesthetics used for management of cancer-related and chronic back pain.

IMPLICATIONS

Acidic bupivacaine administered at the L5 lumbar ganglion causes pain and hypersensitivity of the hind paw in the rat. These findings may explain the limited therapeutic effects of some acidic local anesthetics used for treatment of cancer-related and chronic back pain.

Effects of bupivacaine and ropivacaine on high-voltage-activated calcium currents of the dorsal horn neurons in newborn rats

BACKGROUND

Local anesthetics, such as bupivacaine, have been reported to block calcium currents in primary sensory neurons and to interfere with the release of neurotransmitters in central nervous system neurons. However, it is unknown whether local anesthetics affect the calcium current activity of central nervous system neurons.

METHODS

Using a traditional whole cell voltage clamp technique, effects of bupivacaine and ropivacaine on high-voltage-activated calcium currents (HVA-Ic(a)) were investigated in enzymatically dissociated dorsal horn neurons of neonatal rats. Calcium currents were evoked by testing pulses from a holding potential of -90 to 0 mV.

RESULTS

Bupivacaine significantly reduced HVA-Ic(a) in a dose-dependent manner. The peak HVA-Ic(a) decreased by 24.5+/-2.5, 32.0+/-6.8, 59.4+/-6.2, 88.3+/-1.5, and 91.6+/-1.1% in response to 10, 30, 50, 100 and 200 microM bupivacaine, respectively. Unlike bupivacaine, ropivacaine markedly increased HVA-Ic(a) at lower concentrations (< 50 microM) but decreased HVA-Ic(a) at higher concentrations (> or = 50 microM). The percent increases in peak HVA-Ic(a) induced by 10 and 30 microM ropivacaine were 95+/-19.1 and 41.6+/-8.3%, respectively. The percent decreases in response to 50, 100, and 200 microM ropivacaine were 21.1+/-2.1, 63.2+/-6.0 and 79.1+/-7.6%, respectively. Results indicate that the inhibitory potency of ropivacaine on HVA-Ic(a) was significantly lower than that of bupivacaine at the same concentrations.

CONCLUSIONS

The current study showed that bupivacaine inhibited HVA-Ic(a) recorded from dorsal horn neurons and that ropivacaine increased HVA-Ic(a) at lower concentrations but decreased HVA-Ic(a) at higher concentrations. The inhibitory potency of ropivacaine was lower than that of bupivacaine. Inhibition of calcium currents of central nervous system neurons may be related to the systemic neurotoxic effects of local anesthetics (e.g., convulsions, seizures).

Case report: MR findings of malignant melanoma of the vagina

We report a case in which malignant melanoma of the vagina showed some MR signal changes after radiotherapy. Before radiotherapy, the tumour had slightly high signal intensity on T(1) weighted images and was enhanced after gadolinium-DTPA administration. After radiotherapy, the signal intensity of the tumour increased conspicuously on both T(1) weighted images and fat suppression T(1) weighted images.

[Pollen morphology of bee plants in Changbai Mountain area]

OBJECTIVE

To develop and utilize the bee plants and bee products in Changbai Mountain area, the representative area of alpine plants in northeast China featuring abundant resources of bee plants.

METHOD

The pollen of bee plants was observed and studied by LM and SEM.

RESULT

The pollen is morphologically oblate, suboblate, spheroidal and prolate. The external sculpture is commonly reticulate, striate and echinulate.

CONCLUSION

Plant pollen identification criteria have been furnished for the development of bee plant resources as well as the inspection of bee products in Changbai Mountain area.

Liquid enteral diets induce bacterial translocation by increasing cecal flora without changing intestinal motility

The aim of this study was to determine the contribution of intestinal motility and cecal bacterial overgrowth to liquid diet-induced bacterial translocation (BT). Three different commercially available liquid diets were offered to mice for 1 week. BT to the mesenteric lymph nodes (MLN), spleen, and liver were examined as well as cecal bacterial counts and populations, small bowel length and weight, and histopathologic changes in the ileal and jejunal mucosa. In addition, the effect of the various diets on intestinal motility was measured by the transit index of a charcoal mixture introduced into the stomach. The incidence of BT to the mesenteric lymph nodes was significantly and similarly increased (p < .05) in mice fed Vivonex (30%), Ensure (30%), and Osmolite (33%) compared with chow-fed controls (0%). Compared with chow-fed controls, all three liquid diets were associated with the development of cecal bacterial overgrowth (p < .01). There were no significant changes in the transit index for the three liquid diet groups compared with the chow-fed controls. BT to the MLN was induced by all three liquid diets tested, casting some doubts as to their role in preventing BT in clinical use. BT was associated with a statistically significant increase in cecal bacterial count but was not associated with gut motility changes in this model. In fact, no significant changes in intestinal motility were noted in all groups tested.

Autocrine regulation of norepinephrine transporter expression

The norepinephrine transporter (NET) is a neurotransmitter scavenger and site of drug action in noradrenergic neurons. The aim of this study was to identify mechanisms that regulate NET expression during the development of quail (q) sympathetic neuroblasts, which develop from neural crest stem cells. Neurotrophin-3 (NT-3) and transforming growth factor beta1 (TGF-beta1) cause an increase of qNET mRNA levels in neural crest cells. When combined, the growth factors are additive in increasing qNET mRNA levels. Both NT-3 and TGF-beta1 are synthesized by neural crest cells. Onset of NET expression precedes the onset of neural crest stem cell emigration from the neural tube. In older embryos, qNET is expressed by several crest-derived and noncrest tissues. The data show that qNET expression in presumptive sympathetic neurons is initiated early in embryonic development by growth factors that are produced by neural crest cells themselves. Moreover, the results support our previous observations that norepinephrine transport contributes to the regulation of the differentiation of neural crest stem cells into sympathetic neurons.

Cardioprotective effects of FK409, a nitric oxide donor, after isolated rat heart preservation for 16 hours

BACKGROUND

We examined the cardioprotective effects of FK409, a nitric oxide donor, after isolated rat heart preservation.

METHODS

FK409 was administered to the hearts in pretreatment (FK409-1 group), during ischemia (FK409-2), or during reperfusion (FK409-3). The combined nitrate and nitrite level, coronary flow, cardiac function, coronary vasodilatory response, creatine kinase (CK), and myocardial water content were evaluated after the hearts had been preserved in University of Wisconsin solution at 0 degrees C for 16 hours.

RESULTS

The release of nitrate and nitrite increased in reperfusion between the 20-to-40-second measurement and the measurement at 40 minutes, and the recovery of cardiac function was significantly improved in the FK409 groups. The coronary vasodilatory response to acetylcholine chloride was enhanced in the FK409-1 and FK409-2 groups. CK release decreased in FK409 groups after 15 minutes in reperfusion.

CONCLUSIONS

This study suggests that FK409 has the best protective effect on cardiac function and coronary endothelial function when it is administered in the ischemic period, a less protective effect when administered during pretreatment, and the least protective effect when FK409 is given during reperfusion after heart preservation for 16 hours.

Behavior of lanthanides in countercurrent chromatography using dihexyl-N,N-diethylcarbamoyl methylene phosphonate as stationary phase

Counter-current chromatography is a real liquid-liquid chromatography. The retention volume of the solute can be calculated from the batch distribution ratio in organic separations. In the separations of metal ion, there are several complex and dissociation reactions involved in the two phases, and the retention volume cannot be always predicted from the batch distribution ratio. A mass transfer model is proposed in this paper and an expression of V(R) is derived. The retention volume of metal ion is determined not only by the batch distribution ratio but also by the mechanism of the extraction reaction. When 25% dihexyl-N,N-diethylcarbamoyl methylenephosphonate in cyclohexane is used as stationary phase and 2.91 mol/l HNO3 as mobile phase, the dynamic distribution ratios obtained from the chromatogram are not equal to but proportional to the batch distribution coefficients. These results are in agreement with the theoretical expression.

Perfusion of the mechanically compressed lumbar ganglion with lidocaine reduces mechanical hyperalgesia and allodynia in the rat

The rat L(5) dorsal root ganglion (DRG) was chronically compressed by inserting a hollow perforated rod into the intervertebral foramen. The DRG was constantly perfused through the hollow rod with either lidocaine or normal saline delivered by a subcutaneous osmotic pump. Behavioral evidence for neuropathic pain after DRG compression involved measuring the incidence of hindlimb withdrawals to both punctate indentations of the hind paw with mechanical probes exerting different bending forces (hyperalgesia) and to light stroking of the hind paw with a cotton wisp (tactile allodynia). Behavioral results showed that for saline-treated control rats: the withdrawal thresholds for the ipsilateral and contralateral paws to mechanical stimuli decreased significantly after surgery and the incidence of foot withdrawal to light stroking significantly increased on both ipsilateral and contralateral hind paws. Local perfusion of the compressed DRG with 2% lidocaine for 7 days at a low flow-rate (1 microl/h), or for 1 day at a high flow-rate (8 microl/h) partially reduced the decrease in the withdrawal thresholds on the ipsilateral foot but did not affect the contralateral foot. The incidence of foot withdrawal in response to light stroking with a cotton wisp decreased significantly on the ipsilateral foot and was completely abolished on the contralateral foot in the lidocaine treatment groups. This study demonstrated that compression of the L(5) DRG induced a central pain syndrome that included bilateral mechanical hyperalgesia and tactile allodynia. Results also suggest that a lidocaine block, or a reduction in abnormal activity from the compressed ganglia to the spinal cord, could partially reduce mechanical hyperalgesia and tactile allodynia.

Direct inhibition of G(1) cdk kinase activity by MyoD promotes myoblast cell cycle withdrawal and terminal differentiation

MyoD has been proposed to facilitate terminal myoblast differentiation by binding to and inhibiting phosphorylation of the retinoblastoma protein (pRb). Here we show that MyoD can interact with cyclin-dependent kinase 4 (cdk4) through a conserved 15 amino acid (aa) domain in the C-terminus of MyoD. MyoD, its C-terminus lacking the basic helix-loop-helix (bHLH) domain, or the 15 aa cdk4-binding domain all inhibit the cdk4-dependent phosphorylation of pRb in vitro. Cellular expression of full-length MyoD or fusion proteins containing either the C-terminus or just the 15 aa cdk4-binding domain of MyoD inhibit cell growth and pRb phosphorylation in vivo. The minimal cdk4-binding domain of MyoD fused to GFP can also induce differentiation of C2C12 muscle cells in growth medium. The defective myogenic phenotype in MyoD-negative BC3H1 cells can be rescued completely only when MyoD contains the cdk4-binding domain. We propose that a regulatory checkpoint in the terminal cell cycle arrest of the myoblast during differentiation involves the modulation of the cyclin D cdk-dependent phosphorylation of pRb through the opposing effects of cyclin D1 and MyoD.

Enhanced excitability of sensory neurons in rats with cutaneous hyperalgesia produced by chronic compression of the dorsal root ganglion

Pain and hyperalgesia can occur when the dorsal root ganglion (DRG) and its roots are deformed mechanically in association with injuries or diseases of the spine. To evaluate the electrophysiological changes that contribute to this sensory pathology, intracellular recordings were obtained in vitro from DRGs that had received a chronic mechanical compression [chronic compression of DRG (CCD)]. The compression was produced by inserting L-shaped rods ipsilaterally into the intervertebral foramina, one at L(4) and the other at L(5) in rats 1-14 days before the recording. Control rats received a sham operation. Postoperatively, the threshold force applied by punctate stimulation of the plantar surface of the hind paw decreased significantly on the foot ipsilateral to the CCD (mechanical hyperalgesia) but changed little on the contralateral foot or on either foot for control rats. DRG somata were viewed through a microscope during recording and classified as small, medium, and large according to their diameters. CCD cells in each size category were more excitable than those of comparable size from control rats as judged by the significantly lowered threshold currents and action potential voltage thresholds. Spontaneous activity was recorded in 11% of all the CCD cells tested. The spontaneous activity and/or changes in both the threshold currents and action potential thresholds were observed as early as one day after injury. The association of cutaneous hyperalgesia with changes in the electrophysiological properties of DRG cells suggests a possible role for intrinsic alterations in the membrane properties of compressed DRG cells in the production and persistence of chronic pain after certain spinal injuries or pathologies of the spine.