Minipig model for the study of voiding parameters in the conscious state and natural posture: normal urodynamic profiles

OBJECTIVE

To provide baseline data on an animal model in which collecting and voiding can be accurately characterized urodynamically in the conscious state and natural posture.

METHODS

Thirty-one female Yucatan microswines (age 4-8 months, weight 11-43 kg) were used. Portcatheters were placed in the bladder and peritoneal cavity, and reservoirs were implanted under the back skin for easy access. For urodynamic study, conscious pigs were restrained in specially designed adjustable cages. The portcatheter reservoirs were connected by 20-gauge needles and tubings to a UDS-120 digital computer polygraph to measure the total bladder pressure (pves) and abdominal pressure (pabd). A flow meter was placed behind and underneath the animal to measure the uroflow. Diuresis was induced with furosemide, and 2-4 voiding cycles were monitored. Isovolumetric detrusor pressure (pdet, isv) was obtained in the last cycle by manual interruption of flow per vagina. Urodynamic investigations were performed satisfactorily in all animals.

RESULTS

The voided volume was 102-340 ml (mean 181.7 +/- 11.9 ml). Seven pigs had residual urine (4-39 ml, mean 14.3 +/- 4.7 ml). The initial opening pressure at the start of voiding was 19.9 +/- 1.5 cmH2O; detrusor pressure at maximum flow rate was 15.7 +/- 1.3 cmH2O; average flow was 12.6 +/- 0.7 ml/s; maximum flow rate was 20.7 +/- 1.1 ml/s; pdet, isv was 51.6 +/- 2.4 cmH2O; flow time was 15.9 +/- 1.2 seconds; mean resistance factor (R) was 0.06 +/- 0.01 cmH2O ml-2s2; mean urethral resistance factor (URA) was 7.10 +/- 0.51 cmH2O; and mean strength of voiding detrusor contraction was 3.91 +/- 0.20 W/m2.

CONCLUSION

The above model allows reliable measurement of pressure-flow parameters in the conscious state and natural posture, permitting in-vivo urodynamic characterization of obstructive voiding dysfunction and correlation with detrusor structure.

Induction of cyclooxygenase-2 by the activated MEKK1 --> SEK1/MKK4 --> p38 mitogen-activated protein kinase pathway

The mitogen-activated protein kinase (MAPK) cascade is believed to function as an important regulator of prostaglandin biosynthesis. Previously we reported that interleukin-1beta induces activation of JNK/SAPK and p38 MAPK with concomitant up-regulation of cyclooxygenase (Cox)-2 expression and prostaglandin E2 (PGE2) synthesis. Our experiments demonstrate that overexpression of DeltaMEKK1 (a constitutively active truncation mutant of MEKK1 containing the C-terminal 324 amino acids) increases Cox-2 expression and PGE2 production which is completely blocked by SC68376, a pharmacologic inhibitor of p38 MAPK. DeltaMEKK1 overexpression results in activation of both c-Jun N-terminal kinases/extracellular signal-regulated kinases (JNK/SAPK) and p38 MAPK. Furthermore, activation of MEKK1 increases SEK1/MKK4 but not MKK3 or MKK6 activity. These findings suggest that MEKK1 --> SEK1/MKK4 may function as an upstream kinase capable of activating both p38 MAPK and JNK/SAPK with subsequent induction of Cox-2 expression and PGE2 production. We also found that overexpression of the constitutively active form of SEK1 (SEK1-ED) increases both p38 MAPK and JNK/SAPK phosphorylation, and increases PGE2 production and Cox-2 expression. By comparison, overexpression of the dominant negative form of SEK1 (SEK1-AL) decreases the phosphorylation of both p38 MAPK and JNK/SAPK and reduces Cox-2 expression. Together, this data suggests a potential role for the MEKK1 --> SEK1/MKK4 --> p38 MAPK -->--> Cox-2 cascade linking members of the MAPK pathway with prostaglandin biosynthesis.

IGF-I and insulin amplify IL-1 beta-induced nitric oxide and prostaglandin biosynthesis

The inflammatory cytokine interleukin-1 beta (IL-1 beta) induces both cyclooxygenase-2 (Cox-2) and the inducible nitric oxide synthase (iNOS) with concomitant release of PGs and nitric oxide (NO) by glomerular mesangial cells. In our current studies, we determine whether insulin and IGF-I are involved in the signal transduction mechanisms resulting in IL-1 beta-induced NO and PGE2 biosynthesis in renal mesangial cells. We demonstrate that both insulin and IGF-I increase IL-1 beta-induced Cox-2 and iNOS protein expression, which in turn enhance PGE2 and NO production. Our data also indicate that both insulin and IGF-I enhance IL-1 beta-induced p38 mitogen-activated protein kinase (MAPK) phosphorylation and SAPK activation. These findings implicate the possible role of the MAPK pathway in mediating the effects of insulin and IGF-I on the upregulation of cytokine-stimulated NO and PG biosynthesis. Together, our results indicate that IGF-I and insulin may function to modulate the renal inflammatory process.

Growth factor-like phospholipids generated after corneal injury

The present study provides evidence that growth factor-like glycerophosphate mediators of the lysophosphatidic acid (LPA) family are present in the aqueous humor and the lacrimal gland fluid of the rabbit eye. By use of a combination of HPLC, two-dimensional TLC, mass spectrometry, and the Xenopus oocyte bioassay, the LPA-like phospholipids LPA, cyclic PA, alkenyl-glycerophosphate (GP), lysophosphatidylserine, and phosphatidic acid were detected as physiological constituents of the fluids bathing the cornea. Corneal injury resulted in an increased production of some of these mediators. Alkenyl-GP, a novel member of the LPA family, has been identified in postinjury aqueous humor, establishing that it is generated endogenously. LPA and its homologues were found to be mitogenic in freshly dissociated keratocytes from uninjured corneas. There appears to be a link between the occurrence of LPA responsiveness in keratocytes activated by injury and the increase in LPA-like activity in aqueous humor. These data suggest that LPA and its homologues are involved in maintaining the integrity of the normal cornea and in promoting cellular regeneration of the injured cornea.

[Measurement for optical nonlinearity and optical bistability in II - VI semiconductor by optical waveguide method]

The untransparent substrates on the epitaxial layer need not be etched out from chemistry etching to prepare the "window" through light. The optical absorption, optical nonlinearities and optical bistabilities of the semiconductor thin films with the nanostructure grown on the untransparent substrates can be directly measured by the end face coupling method of optical waveguide. Meanwhile, the several experiment examples of II - VI single crystal thin films and superlattices grown on GaAs substrate are demonstrated in this paper.

Creatine kinase: essential arginine residues at the nucleotide binding site identified by chemical modification and high-resolution tandem mass spectrometry

Phenylglyoxal is an arginine-specific reagent that inactivates creatine kinase (CK). Previous results suggest that modification of the dimeric enzyme at a single arginine residue per subunit causes complete inactivation accompanied by the loss of nucleotide binding; the actual site of modification was not identified. Here, high-resolution tandem mass spectrometry (MS/MS) was used to identify three phenylglyoxal-modified Arg residues in monomeric rabbit muscle CK. Electrospray ionizaton Fourier-transform MS of the phenylglyoxal-modified CK that had lost approximately 80% activity identified three species: unmodified, once-modified (+116 Da), and twice-modified (+232 Da) enzyme in a ratio of approximately 1:4:1. MS/MS restricts the derivatized sites to P122-P212 and P283-V332, whereas MS of Lys-C digestions revealed two modified peptides, A266-K297 and G116-K137. The only Arg in A266-K297 is Arg-291 (invariant), whereas MS/MS of modified G116-K137 shows that two of the three sites Arg-129, Arg-131, or Arg-134 (all invariant) can contain the modification. The recently reported x-ray crystal structure for the octameric chicken mitochondrial CK indicates that its nucleotide triphosphate-binding site indeed contains the equivalent of R291, R129, and R131 reported here to be at the active site of rabbit muscle CK.

[A phase II clinical study of China-made paclitaxel in the treatment of cancer patients]

OBJECTIVE

To evaluate the efficacy and toxicity of China-made paclitaxel in patients with a variety of advanced malignancies.

METHODS

Paclitaxel was administered by i.v. infusion at a dose of 175 mg/m2 in 3-hour every three weeks. All patients received premedication(dexamethasone, diphenhydramine and cimetidine) to prevent allergic reactions.

RESULTS

Of 116 patients, 114 patients received 2 to 3 courses of therapy and were evaluable for response. The overall response rate for ovarian cancer was 46.7%, for breast cancer 56.4%, for non-small-cell lung cancer 25.0%, for small-cell lung cancer 66.7%, and for nasopharyngeal cancer 41.7%. Responses were also achieved in patients who had failed to respond to prior chemotherapy, with the overall response rate of 42.9% for ovarian cancer, 57.6% for breast cancer, 33.3% for non-small-cell lung cancer, 25.0% for small-cell lung cancer, and 40.0% for nasopharyngeal cancer. Paclitaxel did not show cross-resistance with doxorubicin and cisplatin. The major toxicity associated with paclitaxel included neutropenia, arthralgia, myalgia, numbness of hands and feet and alopecia. No severe hypersensitivity reactions were observed.

CONCLUSION

At the above-mentioned dose and schedule, paclitaxel is effective with tolerable side effects.

[Changes of coenzyme Q content in brain tissues of rats with fluorosis]

Animal models with pathological damage caused by chronic fluorosis to a different extent were duplicated in Wistar rats by feeding them with 66.3 mg/L and 221 mg/L fluorine-containing water for three, five and seven months, respectively. Cholesterol, dolichol and coenzyme Q in animal brain tissues were determined by high performance liquid chromatography. Results showed that no significant difference of cholesterol and dolichol contents in brian tissues between rats with fluorosis and normal controls were detected. Coenzyme Q content of brain tissue in rats fed with fluorine-containing water decreased at early stage of fluorosis, but increased significantly at late stage. It is speculated that changes in content of coenzyme Q could correlate with changes in free radical levels induced by fluorine.

Phorbol ester modulation of rabbit corneal endothelial permeability

PURPOSE

Phorbol esters have been shown to have a profound influence on cellular activity in many cell types. The purpose of this study was to examine the influence of phorbol esters on the function and structure of corneal endothelial cells.

METHODS

Corneas were placed under a specular microscope, and the endothelium was superfused with glutathione bicarbonate Ringer's solution (GBR); with GBR and 10 nM, 100 nM, or 1 microM 4 beta-phorbol 12-myristate 13-acetate (PMA); or with 100 nM 4-alpha-PMA. Corneal swelling curves were generated, and endothelial permeability was determined. Corneal endothelial structure was examined with a scanning electron microscope.

RESULTS

Significant increases in swelling and endothelial permeability were found in corneas perfused with 100 nM PMA versus that observed in controls (swelling rate = 26 microns/hr versus 6.9 microns/hr; permeability = 6 x 10(-4) cm/min versus 3.4 x 10(-4) cm/min) and in corneas receiving 1 microM PMA versus that in controls (swelling rate = 26.3 microns/hr versus 0.12 micron/hr; permeability = 6.9 x 10(-4) cm/min versus 4.9 x 10(-4) cm/min). Application of 10 nM PMA did not significantly alter either parameter. Study with transmission electron microscope demonstrated significant morphologic changes in cells perfused with all concentrations of PMA. Corneas perfused with 100 nM 4-alpha-PMA versus 100 nM PMA had significantly lower slope and permeability values (swelling rate = 5.9 microns/hr versus 25.1 microns/hr; permeability = 3 x 10(-4) cm/min versus 6.7 x 10(-4) cm/min).

CONCLUSIONS

Phorbol esters are detrimental for corneal endothelial function, creating significant corneal swelling, increases in endothelial permeability, and changes in endothelial cell structure. This effect appears to be mediated through a protein kinase C pathway.

[Laser transnasal dacryocystorhinostomy under head mirror]

Laser transnasal dacryocystorhinostomy under head mirror is a new approach for surgical treatment of chronic lacrimal obstruction. This technique has several advantages, such as less damage, less operative complications and so on. This paper presented the results of 37 cases who had undergone transnasal dacryocystorhinostomy for chronic dacryocystitis under head mirror. The postoperative follow-up time was 3-24 months. The effective rate was 95.6%. The operative technique was also discussed in this paper.

[Influence of experimental fluorosis on phospholipid content and fatty acid composition in rat brain]

OBJECTIVE

To investigate the pathogenesis of brain damage by fluoride intoxication, phospholipid content, and fatty acid composition in rat brain with fluorosis were annlysed.

METHODS

Wistar rats were fed with NaF in various amounts and time periods to produce the animal model with chronic fluorosis. Phospholipid content and fatty acids composition were analysed using high performance liquid chromatography and gas chromatography, respectively.

RESULTS

All animals fed with high amount of fluoride suffered from chronic fluorosis. The total brain phospholipid content was lower in the rat treated with fluoride, which mainly influenced phosphatidylethanolamine, phosphatidylcholin, and phosphatidylserine. No modifications were detected in fatty acid and aldehyde compositions of individual phospholipid classes.

CONCLUSION

The metabolism of brain phospholipid might be interfered by fluoride accumulated in brain tissue, which is related with the degeneration of neuron. The changes of brain phospholipid could be involved in the pathogenesis of chronic fluorosis.

[Brain dialysis--a new technique for determining the release of neurotransmitters and neuropeptides]

Brain dialysis, also called microdialysis, is a new technique based on the push-pull cannula. It can be used for continuously perfusing and collecting perfusate of certain brain areas in freely moving animals. Coupled with high performance liquid chromatography (HPLC) and radioimmunoassay (RIA), brain dialysis is allowed to determine the extracellular changes of many neurotransmitters in the brain, such as acetylcholine, noradrenaline, dopamine, 5-HT and their metabolites, free amino acids, small peptides, phosphoethanolamine, vitamins, various ions and so on.

A glucose-sensing polymer

We have prepared a robust polymer that can be used to measure glucose concentrations in complex biological media. At alkaline pH, the metal-complexing polymer binds glucose and instantly releases protons in proportion to the glucose concentration over a clinically relevant range (0 to 25 mM). The inexpensive polymer is sufficiently selective to provide an easily measurable response to glucose in porcine plasma. The polymer's ability to function at nonphysiological pH (at which the buffer capacity of biological samples is small) makes it possible to design simple and inexpensive sensing devices based on measurement of changes in proton concentration.

p38 mitogen-activated protein kinase down-regulates nitric oxide and up-regulates prostaglandin E2 biosynthesis stimulated by interleukin-1beta

The inflammatory cytokine interleukin 1beta (IL-1beta) induces both cyclooxygenase-2 (Cox-2) and the inducible nitric-oxide synthase (iNOS) with increases in the release of prostaglandins (PGs) and nitric oxide (NO) from glomerular mesangial cells. However, the intracellular signaling mechanisms by which IL-1beta induces iNOS and Cox-2 expression is obscure. Our current studies demonstrate that IL-1beta produces a rapid increase in p38 mitogen-activated protein kinase (MAPK) phosphorylation and activation. Serum starvation and SC68376, a drug which selectively inhibits p38 MAPK in mesangial cells, were used to investigate whether p38 MAPK contributes to the signaling mechanism of IL-1beta induction of NO and PG synthesis. Serum starvation and SC68376 selectively inhibited IL-1beta-induced activation of p38 MAPK. Both SC68376 and serum starvation enhanced NO biosynthesis by increasing iNOS mRNA expression, protein expression, and nitrite production. In contrast, both SC68376 and serum starvation suppressed PG release by inhibiting Cox-2 mRNA, protein expression, and PGE2 synthesis. These data demonstrate that IL-1beta phosphorylates and activates p38 MAPK in mesangial cells. The activation of p38 MAPK may provide a crucial signaling mechanism, which mediates the up-regulation of PG synthesis and the down-regulation of NO biosynthesis induced by IL-1beta.

Purinergic Ca2+ signaling in myenteric neurons via P2 purinoceptors

Fura 2 microfluorimetry was used to test the hypothesis that ATP acts at P1 and P2 purinoceptors to elevate cytosolic free Ca2+ concentrations [Ca2+]i) in calbindin-immunoreactive cultured myenteric neurons from adult guinea pig small intestine. Local "micro-puff" application of ATP or ATP(gamma)S caused an increase in [Ca2+]i in 99% of 200 multipolar neurons. The potency profile of agonists for the rise in [Ca2+]i was ATP(gamma)S = ATP >> ADP >> AMP, adenosine, 5'-(N-ethylcarboxamido)adenosine, and 2-chloro-N(6)-cyclopentyladenosine. Tetrodotoxin-sensitive synaptic transmission could contribute as much as 25% to the ATP response. The P1 antagonist 8-cyclopentyl-1,3-dipropylxanthine blocked 50% of the peakATP Ca2+ response. P2 antagonists blocked the ATP response: pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid > reactive blue 2 > suramin. Suramin enhanced the ATP response in 27.5% of neurons. Some neurons (<15%) displayed distinct multiphasic Ca2+ signatures. About 54% of ATP-responsive neurons expressed calbindin. The data support the following hypotheses: 1) two distinct P2 purinoceptors are linked to the rise in [Ca2+]i in myenteric neurons; 2) purinergic Ca2+ signaling is not restricted to one neuronal phenotype; and 3) intraneuronal Ca2+ is not involved in adenosinergic hyperpolarization in AH/type 2 neurons.

[Clinical observation of the pathological changes of axial length, corneal curvature and posterior segment wall of eyeball in eyes with high myopia]

PURPOSE

To study the correlation between the characteristics of the morphologic changes in the wall of eyeball with high myopia and the visual function.

METHODS

The axial length, corneal curvature, etc., of 280 eyes in 140 cases (the diopter was from -6.25D to approximately -30.00D) were examined and the data were settled statistically.

RESULTS

(1) The corrected visual acuity in the patents with high myopia decreased apparently with the increase of diopter. The difference was significant (P < 0.001). (2) The axial length of anteroposterior diameter in 96.1% eyes increased, with which the diopter also increased. (3) 27.1% exophthalmos were forward. (4) There was no significant difference when compared the anterior surface corneal curvature with emmetropic eyes. (5) Posterior scleral staphyloma occurred in 80.7% eyes. (6) Optic nerve atrophy and optic disk atrophic arc spot occurred in 82.3% eyes. (7) The intraocular pressure increases in 5.3% eyes.

CONCLUSION

The severe damage to the visual function because of the pathological changes on the wall of eyeball is the main cause that vision can not be corrected in clinics.

Activation of elements of the phosphatidylinositol pathway in the primate corpus luteum by prostaglandin E2

The current study was designed to examine the effects of prostaglandin (PG) E2 on progesterone production by primate luteal cells collected during the late luteal phase. PGE2 inhibited basal and human chorionic gonadotrophin (HCG)-stimulated progesterone production (P < 0.01) in late luteal phase corpora lutea. The ability of PGE2 to activate a second messenger system (phosphatidylinositol pathway) in corpora lutea of rhesus monkeys was also assessed. PGE2 significantly increased the accumulation of inositol phosphates (P < 0.05). This stimulation was not apparent in the early luteal phase but was manifested in the mid-late luteal phase. PGE2 also caused a rapid, yet transient, increase (P < 0.01) in intracellular free calcium ion concentrations ([Ca2+]i) in a large proportion of primate luteal cells. The proportion of luteal cells that responded to PGE2 with an increase in [Ca2+]i was smaller (P < 0.05) in corpora lutea collected during the early luteal phase (12%) in comparison with those collected during the latter half of the luteal phase (63-66%). Changes in [Ca2+]i in response to PGE2 were similar in small and large luteal cells. This study demonstrates that PGE2 activates elements of the phosphatidylinositol pathway in primate corpora lutea. This activation is augmented as the luteal phase progresses. Thus, the inhibitory effects of PGE2 on luteal progesterone production observed in the late luteal phase are associated with activation of elements of the phosphatidylinositol pathway.

Effect of tumor necrosis factor alpha on rabbit corneal endothelial permeability

PURPOSE

Tumor necrosis factor alpha (TNF alpha) is present in the iris and the lacrimal gland, and its concentration is increased during inflammation and after corneal wounding. Although TNF alpha has been shown to increase keratocyte and corneal epithelial interleukin production, no definitive effects of TNF alpha on corneal endothelial cells have been reported. TNF alpha has been shown to disrupt barrier function in vascular endothelial monolayers through f-actin depolymerization. A reduction in intracellular cyclic adenosine monophosphate (cAMP) concentration may play a role in this response. This study was designed to examine the role and signal transduction mechanisms of TNF alpha modulation of endothelial permeability in the cornea. In addition, it is the first examination of the effects of TNF alpha on the barrier function of a noncultured cell monolayer.

METHODS

Rabbit corneal endothelial superfusions were performed under an in vitro specular microscope. Corneas were processed for permeability measurements or f-actin staining.

RESULTS

TNF alpha superfused corneas had significantly higher permeabilities than controls. f-actin staining revealed that TNF alpha superfusion disrupted f-actin filaments when compared to controls. Corneas superfused with the f-actin stabilizing agent phallacidin had significantly lower permeabilities than TNF alpha superfused pairs. Permeabilities of corneas superfused with TNF alpha plus 8-bromo-cAMP (0.01 to 3 mM) were significantly lower than TNF alpha superfused pairs at all concentrations, although only significantly lower at the 0.1 mM cAMP concentration.

CONCLUSIONS

TNF alpha causes an increase in corneal endothelial permeability, and this increase is mediated by disruption of f-actin filaments; cAMP appears to be involved in this response.

Responsiveness to ATP with an increase in intracellular free Ca2+ is not a distinctive feature of calbindin-D28 immunoreactive neurons in myenteric ganglia

The aim of this study was to test the hypothesis that ATP elevates cytosolic free Ca2+ levels ([Ca2+]i) in myenteric neurons expressing the Ca2+ binding protein, calbindin-D28. A laser microbeam marked the location of cultured neurons on coverslips and provided unequivocal relocation of ATP-responsive neurons after immunocytochemistry. All myenteric multipolar neurons displayed ATP Ca2+ transients, and 42% also expressed calbindin-D28 reactivity. Statistical analysis of the kinetics and shape of ATP Ca2+ transients revealed no differences between calbindin and non-calbindin neurons. The identity of other responsive neurons is unknown. Less than 8% of ganglion cells with ATP Ca2+ transients were immunopositive for the glial protein S-100. We conclude that one of the actions of ATP in myenteric ganglia is to increase [Ca2+]i which may activate gKCa leading to membrane hyperpolarization in AH, Dogiel Type II neurons expressing calbindin-D28. An efficient buffering mechanism for handling large purinergic Ca2+ loads is a common feature of all types of myenteric ganglion cells.

[Significance of the expression of HLA-DR on keratinocytes in oral lichen planus lesions]

In this article, the expression of HLA-DR in keratinocytes in lesions of oral lichen planus (OLP) was investigated, using an immunohistochemical technique (PAP method). The results showed: HLA-DR positive keratinocytes were found in all groups of patients, the numbers and expressive degree of HLA-DR were related to types and duration of OLP, there were higher statistically significant differences between different groups and types of OLP (P < 0.01). The authors considered that the expression of HLA-DR in keratinocytes plays an important role in gathering T cells and forming inflammation in OLP lesions.

Nitric oxide amplifies interleukin 1-induced cyclooxygenase-2 expression in rat mesangial cells

Interleukin 1 and nitric oxide (NO) from infiltrating macrophages and activated mesangial cells may act in concert to sustain and promote glomerular damage. To evaluate if such synergy occurs, we evaluated the effect if IL-1 beta and NO on the formation of prostaglandin (PG)E2 and cyclooxygenase (COX) expression. The NO donors, sodium nitroprusside and S-nitroso-N-acetylpenicillamine, alone did not increase basal PGE2 formation. However, these compounds amplified IL-1 beta-induced PGE2 production. Similarly, sodium nitroprusside and S-nitroso-N-acetylpenicillamine by themselves did not induce mRNA and protein for COX-2, the inducible isoform of COX; however, they both potentiated IL-1 beta-induced mRNA and protein expression of COX-2. The stimulatory effect of NO is likely to be mediated by cGMP since (a) an inhibitor of the soluble guanylate cyclase, methylene blue, reversed the stimulatory effect of NO donors on COX-2 mRNA expression; (b) the membrane-permeable cGMP analogue, 8-Br-cGMP, mimicked the stimulatory effect of NO donors on COX-2-mRNA expression; and (c) atrial natriuretic peptide, which increases cellular cGMP by activating the membrane-bound guanylate cyclase, also amplified IL-1 beta-induced COX-2 mRNA expression. These data indicate a novel interaction between NO and COX pathways.

Broadband quadrupolar axialization of large multiply charged ions to enhance measurement and minimize conformational restrictions

For high-resolution Fourier transform mass spectrometry of electrosprayed proteins, the signal-to-noise ratio of measuring nozzle-skimmer fragment ions can be improved substantially by their broadband quadrupolar axialization (QA), even without increasing their concentration in the ion cyclotron resonance cell. Axialization of the product ions makes possible larger, more concentric ion orbits for measurements. QA allowed the identification of new sequence-indicative product ions from a 29 kDa protein. However, QA of large molecular ions gives little increase in signal, consistent with original trapping near the cell axis. By recentering of ions undergoing ion-molecule reactions, these can be carried out at much higher kinetic energy and pressures; for cytochrome c this increases the achievable H-D exchange by 40%, corresponding to exchange at all the active sites of its completely denatured conformer.

[Effect of dexamethasone on the human interleukin-2 receptor alpha chain gene expression]

Glucocorticoids have wide effects on the immune system, the mechanisms of these effects have not been clearly defined. The interaction of interleukin-2 (IL-2) with its receptor (IL-2R) is a critical control point in the T-cell mediated immune response. The effect of dexamethasone, a synthetic glucocorticoid hormone, on IL-2R is unclear in comparison with its inhibition on the accumulation of IL-2 mRNA. Our study shows that dexamethasone increases the basal and PHA-induced mRNA levels of IL-2R alpha gene in Jurkat cells, but it does not affect the expression of reporter gene constructs containing 5' flanking sequences (-482bp/ +16bp or -350bp/+16bp) of the IL-2R alpha gene in PHA activated Jurkat cells. These results indicate that dexamethasone plays a positive regulatory role in the IL-2R alpha gene expression, but the effect is not mediated by the previously identified proximal regulatory elements located between -482bp/+1bp. Meanwhile, our results also provide evidence that the activation mechanism of dexamethasone is different from that of PHA, and that dexamethasone and PHA show a synergistic effect in the induction of IL-2R alpha gene expression.