Single-level fusion without decompression for high-grade spondylolithesis in adolescents: a novel surgical strategy.

PURPOSE: There is no consensus on the optimal surgical treatment for high-grade spondylolisthesis (HGS) in adolescents. The purpose of this study was to assess the radiographic and clinical outcomes of a novel surgical approach to HGS consisting of a single-level anterior reduction, placement of a lordotic cage, and circumferential fixation without decompression. METHODS: This was a retrospective consecutive case series of 11 adolescents who underwent anterior reduction through placement of a lordotic cage followed by posterior fusion using pedicle screws and rods confined to L5-S1. Radiographic data included slip percentage, slip angle, lumbar lordosis, and pelvic sagittal parameters assessed at clinical visits preoperatively and at 2 years postoperatively. A telephone survey was conducted to obtain current information about function, activity level, work status, and retrograde ejaculation. RESULTS: Patients were followed for an average of 7.8 years (range 2-16). Mean age was 15.5 years (range 12-19). The mean percent slip corrected from 55 to 18%. The average slip angle was + 17.1° preoperatively and - 14.1° at final assessment (average correction of 20.7°). Thirty-six percent (4/11) of patients improved by three Meyerding grades and an additional 55% (6/11) improved by two grades. Complications included one instance each of superficial infection, wound dehiscence, and transient neuralgia. There were no cases of instrumentation failure, cage subsidence, pseudoarthrosis, or retrograde ejaculation. Radiographic evidence of fusion was observed in all cases. CONCLUSION: Single-level anterior reduction and circumferential fusion without decompression appears to be a safe and effective alternative for the surgical treatment of pediatric HGS. LEVEL OF EVIDENCE: IV.

Koala methylomes reveal divergent and conserved DNA methylation signatures of X chromosome regulation.

X chromosome inactivation (XCI) mediated by differential DNA methylation between sexes is an iconic example of epigenetic regulation. Although XCI is shared between eutherians and marsupials, the role of DNA methylation in marsupial XCI remains contested. Here, we examine genome-wide signatures of DNA methylation across fives tissues from a male and female koala (Phascolarctos cinereus), and present the first whole-genome, multi-tissue marsupial 'methylome atlas'. Using these novel data, we elucidate divergent versus common features of representative marsupial and eutherian DNA methylation. First, tissue-specific differential DNA methylation in koalas primarily occurs in gene bodies. Second, females show significant global reduction (hypomethylation) of X chromosome DNA methylation compared to males. We show that this pattern is also observed in eutherians. Third, on average, promoter DNA methylation shows little difference between male and female koala X chromosomes, a pattern distinct from that of eutherians. Fourth, the sex-specific DNA methylation landscape upstream of Rsx, the primary lncRNA associated with marsupial XCI, is consistent with the epigenetic regulation of female-specific (and presumably inactive X chromosome-specific) expression. Finally, we use the prominent female X chromosome hypomethylation and classify 98 previously unplaced scaffolds as X-linked, contributing an additional 14.6 Mb (21.5%) to genomic data annotated as the koala X chromosome. Our work demonstrates evolutionarily divergent pathways leading to functionally conserved patterns of XCI in two deep branches of mammals.

Missed radiographic and clinical findings in a case of non-idiopathic scoliosis resulting from chondroblastoma.

PURPOSE: Chondroblastoma is a cartilaginous neoplasm which rarely presents in the spine, where it has been shown to exhibit aggressive behavior. We present a case of a late diagnosis of a T12 chondroblastoma causing paraparesis in an 11-year-old girl. Several missed classical radiographic and clinical features are highlighted. METHODS: We reviewed clinical, imaging, and pathology data from the time of transfer to our institution, followed by review of all outside clinical records and imaging data from 14 months prior to admission until onset of paraplegia. RESULTS: The patient was transferred to our center for emergent treatment of a large, expansile, exophytic lesion compressing the spinal cord at T12. Intravenous steroids improved her neurologic status to ASIA Grade B, and an en bloc posterior element resection was performed emergently within 24 h. She rapidly improved to an ASIA Grade E. After obtaining all prior imaging during detailed histopathologic work-up, the final diagnosis was that of spinal chondroblastoma. Subsequent anterior en bloc resection was performed. The patient remains disease-free with a stable, residual scoliosis 7 years postoperatively. CONCLUSIONS: Detailed review of radiographs is essential for scoliosis patients. Earlier recognition of the "winking owl" sign, a kyphotic sagittal alignment, and more concern about a child with a painful curve may have resulted in earlier diagnosis before the onset of neurologic deficits.

The exploration of aza-quinolines as hematopoietic prostaglandin D synthase (H-PGDS) inhibitors with low brain exposure.

GlaxoSmithKline and Astex Pharmaceuticals recently disclosed the discovery of the potent H-PGDS inhibitor GSK2894631A 1a (IC50 = 9.9 nM) as part of a fragment-based drug discovery collaboration with Astex Pharmaceuticals. This molecule exhibited good murine pharmacokinetics, allowing it to be utilized to explore H-PGDS pharmacology in vivo. Yet, with prolonged dosing at higher concentrations, 1a induced CNS toxicity. Looking to attenuate brain penetration in this series, aza-quinolines, were prepared with the intent of increasing polar surface area. Nitrogen substitutions at the 6- and 8-positions of the quinoline were discovered to be tolerated by the enzyme. Subsequent structure activity studies in these aza-quinoline scaffolds led to the identification of 1,8-naphthyridine 1y (IC50 = 9.4 nM) as a potent peripherally restricted H-PGDS inhibitor. Compound 1y is efficacious in four in vivo inflammatory models and exhibits no CNS toxicity.

Enhanced Recovery After Pediatric Scoliosis Surgery: Key Components and Current Practice.

With the goal of safety and efficiency in health care delivery, enhanced recovery protocols (ERPs) continue to gain traction throughout various surgical disciplines, including in pediatric scoliosis surgery. The growing body of literature reporting decreased length of stay and cost with no change in readmissions or complications has brought these protocols to the forefront. The key components of ERPs include preoperative patient counseling, perioperative pain management, and early patient mobilization. In this review, the authors aim to describe the foundational history and major components of ERPs following pediatric spine deformity surgery. [Orthopedics. 2020;43(5):e338-e344.].

Trauma induced heterotopic ossification patient serum alters mitogen activated protein kinase signaling in adipose stem cells.

Post-traumatic heterotopic ossification (HO) is the formation of ectopic bone in non-osseous structures following injury. The precise mechanism for bone development following trauma is unknown; however, early onset of HO may involve the production of pro-osteogenic serum factors. Here we evaluated serum from a cohort of civilian and military patients post trauma to determine early induction gene signatures in orthopaedic trauma induced HO. To test this, human adipose derived stromal/stem cells (hASCs) were stimulated with human serum from patients who developed HO following trauma and evaluated for a gene panel with qPCR. Pathway gene analysis ontology revealed that hASCs stimulated with serum from patients who developed HO had altered gene expression in the activator protein 1 (AP1) and AP1 transcriptional targets pathways. Notably, there was a significant repression in FOS gene expression in hASCs treated with serum from individuals with HO. Furthermore, the mitogen-activated protein kinase (MAPK) signaling pathway was activated in hASCs following serum exposure from individuals with HO. Serum from both military and civilian patients with trauma induced HO had elevated downstream genes associated with the MAPK pathways. Stimulation of hASCs with known regulators of osteogenesis (BMP2, IL6, Forskolin, and WNT3A) failed to recapitulate the gene signature observed in hASCs following serum stimulation, suggesting non-canonical mechanisms for gene regulation in trauma induced HO. These findings provide new insight for the development of HO and support ongoing work linking the systemic response to injury with wound specific outcomes.

Primary Osteomyelitis of the Clavicle in Children.

Osteomyelitis of the clavicle is a rare entity with a broad differential diagnosis and high potential for complications if not diagnosed promptly and treated appropriately. The threshold for surgical intervention should be low to prevent osteonecrosis and bony resorption. In addition, although rare, life-threatening complications have been reported. This report describes primary osteomyelitis of the clavicle that was diagnosed in a 22-month-old girl on her third clinical evaluation after 4 days of symptoms. She presented to a children's tertiary care emergency department with fever and acute pain and swelling of her right shoulder and arm. The diagnosis was confirmed through clinical, laboratory, and imaging studies including ultrasound; these revealed subperiosteal abscess formation, which may have developed in part as the result of a delayed diagnosis from the 2 prior emergency department visits. The patient was treated initially with intravenous antibiotics and underwent therapeutic as well as diagnostic needle-guided tissue aspiration under ultrasound guidance. This ruled out malignancy but was not curative, and the subperiosteal abscess recurred within 24 hours, prompting formal operative irrigation and debridement. The patient was seen for 12-month follow-up and has had no complications or evidence of recurrence. This case emphasizes the need for a high index of suspicion to prevent diagnostic delays as well as the importance of a low threshold for surgical debridement to minimize the potential for complications that could prolong the treatment course. [Orthopedics. 2016; 39(4):e760-e763.].

A transcriptome resource for the koala (Phascolarctos cinereus): insights into koala retrovirus transcription and sequence diversity.

BACKGROUND: The koala, Phascolarctos cinereus, is a biologically unique and evolutionarily distinct Australian arboreal marsupial. The goal of this study was to sequence the transcriptome from several tissues of two geographically separate koalas, and to create the first comprehensive catalog of annotated transcripts for this species, enabling detailed analysis of the unique attributes of this threatened native marsupial, including infection by the koala retrovirus. RESULTS: RNA-Seq data was generated from a range of tissues from one male and one female koala and assembled de novo into transcripts using Velvet-Oases. Transcript abundance in each tissue was estimated. Transcripts were searched for likely protein-coding regions and a non-redundant set of 117,563 putative protein sequences was produced. In similarity searches there were 84,907 (72%) sequences that aligned to at least one sequence in the NCBI nr protein database. The best alignments were to sequences from other marsupials. After applying a reciprocal best hit requirement of koala sequences to those from tammar wallaby, Tasmanian devil and the gray short-tailed opossum, we estimate that our transcriptome dataset represents approximately 15,000 koala genes. The marsupial alignment information was used to look for potential gene duplications and we report evidence for copy number expansion of the alpha amylase gene, and of an aldehyde reductase gene.Koala retrovirus (KoRV) transcripts were detected in the transcriptomes. These were analysed in detail and the structure of the spliced envelope gene transcript was determined. There was appreciable sequence diversity within KoRV, with 233 sites in the KoRV genome showing small insertions/deletions or single nucleotide polymorphisms. Both koalas had sequences from the KoRV-A subtype, but the male koala transcriptome has, in addition, sequences more closely related to the KoRV-B subtype. This is the first report of a KoRV-B-like sequence in a wild population. CONCLUSIONS: This transcriptomic dataset is a useful resource for molecular genetic studies of the koala, for evolutionary genetic studies of marsupials, for validation and annotation of the koala genome sequence, and for investigation of koala retrovirus. Annotated transcripts can be browsed and queried at http://koalagenome.org.

Comparison of infrapatellar and subcutaneous adipose tissue stromal vascular fraction and stromal/stem cells in osteoarthritic subjects.

Since inflammatory mechanisms have been postulated to link obesity to osteoarthritis, the current study evaluated the ratio of immune cells to multipotent stromal cells within the infrapatellar fat pad (IPFP) and subcutaneous adipose tissue (SQ) of the knee; each depot has potential as a source of regenerative cells. The immunophenotypes of stromal vascular fraction (SVF) and adipose-derived stem cells (ASCs) of the IPFP and SQ were determined in tissues from osteoarthritic subjects (n = 7) undergoing total knee replacement. Based on a subset of surface antigens, the immunophenotype of ASCs from SQ of OA subjects was not significantly different from that of relatively healthy and leaner subjects undergoing elective liposuction surgery. Flow-cytometry comparison of SVF cell populations in the IPFP of OA subjects resembled those within the subject's own matched SQ, with the exception of the endothelial marker CD31(+) , which was significantly greater in cells from SQ. In the OA subjects, lower numbers of capillary-like structures and higher numbers of stromal and alkaline phosphatase colony-forming units in the IPFP vs SQ were consistent with this finding; however, ASCs from both depots in OA subjects exhibited comparable adipogenic and osteogenic differentiation potential. Thus, the IPFP contains an ASC and immune cell population similar to that of donor-matched SQ, making it an alternative ASC source for tissue regeneration. Further studies will be needed to determine whether IPFP immune cell infiltrates play an aetiological role in osteoarthritis equivalent to that shown in diabetes associated with obesity.

Assessing a novel depot delivery strategy for noninvasive administration of VEGF/PDGF RTK inhibitors for ocular neovascular disease.

PURPOSE: Two noninvasive delivery strategies for VEGF/PDGF receptor tyrosine kinase inhibitors (RTKI) were explored that exploited uveal retention as a means for establishing an ocular drug depot: a single oral "loading" dose and topical administration. METHODS: Melanin binding was confirmed by centrifugation and mass spectrometry. Ocular retention was examined in pigmented and albino rats. Ocular release kinetics were measured 3 to 28 days postdosing in pigmented rats. Microautoradiography was used to demonstrate retention of RTKI in the uveal tract. A uveal drug depot of pazopanib was created by a single oral dose prior to induction of laser choroidal neovascularization (CNV). Choroid/retinal pigmented epithelium (RPE) retention of a related RTKI with enhanced topical bioavailability, GW771806, was confirmed by bioanalytics, and its ability to regress CNV compared with pazopanib. RESULTS: Pazopanib and GW771806 directly bound melanin and were retained within the uveal tract of pigmented rats for weeks following a single oral dose. Pazopanib was undetectable systemically following a single oral administration prior to CNV induction, and reduced CNV as well as twice daily dosing. Topical ocular delivery of GW771806 at 5 mg/mL led to high choroidal/RPE exposure and significantly regressed CNV lesions; 2 mg/mL prevented lesion progression. CONCLUSIONS: Uveal retention of drugs such as pazopanib can be used to create a sustained-release depot. Topical GW771806 regressed CNV. These data indicate that topical or infrequent oral loading dose treatment with VEGF/PDGF RTKI retained in the choroid/RPE might allow noninvasive treatments for ocular neovascular disease.

Rapid characterization of mitochondrial genome rearrangements in Australian songbirds using next-generation sequencing technology.

Using next-generation sequencing technology, we describe the complete mitochondrial genomes for 5 Australian passerine birds (Epthianura albifrons, Petroica phoenicea, Petroica goodenovii, Petroica boodang, and Eopsaltria australis). We successfully assemble each mitogenome de novo using just 1/8th of a Roche GL FSX 454 pyrosequencing plate. From the assembled mitogenomes, we identify 2 different mitochondrial gene arrangements in the region spanning 5'-3' from Cytochrome B to 12s RNA. These gene arrangements represent 2 of the 4 known avian mitochondrial gene arrangements. Our results, together with other previously described avian mitogenomes, highlight that certain mitochondrial rearrangements appear to have arisen multiple times.

Anti-angiogenic effects of the receptor tyrosine kinase inhibitor, pazopanib, on choroidal neovascularization in rats.

Neovascularization in the eye is a major cause of irreversible vision loss. The present study was undertaken to determine mechanisms through which pazopanib, a drug that targets multiple receptor tyrosine kinases such as VEGF receptors, inhibits angiogenesis and experimental choroidal neovascularization (CNV). Pazopanib inhibited VEGF expression by retinal pigment epithelium (RPE) cells and choroidal endothelial cells (CEC), decreased VEGF-induced cellular migration in a dose-dependent manner and suppressed extracellular signal-regulated kinase (ERK)-1/-2 phosphorylation. To assess the impact of pazopanib in vivo, CNV was induced in rats by rupturing the Bruch's membrane by laser coagulation. These experiments demonstrated that twice-daily topical eye drop treatment significantly (P<0.001) decreased leakage from photocoagulated lesions by 89.5%. Furthermore, the thickness of the developed CNV lesions was significantly inhibited by 71.7% (P<0.001) in pazopanib-treated eyes, and immunoreactivity of VEGF was lower than in control eyes. Our data suggest that pazopanib is a promising inhibitor of angiogenesis leading to an effective inhibition of CNV development in vivo. This activity can be largely ascribed to the down-regulation of VEGF release in the retina as well as to impaired VEGF-induced signaling and chemotaxis. Using a convenient topical dosing regimen, pazopanib may prove useful for treating a variety of ocular neovascular diseases such as neovascular age-related macular degeneration.

Suppression and regression of choroidal neovascularization by the multitargeted kinase inhibitor pazopanib.

OBJECTIVE: To investigate pazopanib hydrochloride, a multitargeted kinase inhibitor, for treatment of choroidal neovascularization (CNV). METHODS: Choroidal neovascularization was induced in mice by rupture of Bruch membrane with laser photocoagulation. Mice were treated with pazopanib by gavage or periocular injection, and the area of CNV was measured. RESULTS: Twice-daily gavage of pazopanib, 100 mg/kg, suppressed the development of CNV by 93%. Treatment of established CNV between days 7 and 14 with 8, 40, or 200 mg/kg per day reduced CNV by 0%, 58%, and 71%, respectively. Substantial regression (40%) of CNV was also achieved after periocular injection of pazopanib. A single oral dose of 4 or 100 mg/kg resulted in an area under the curve from time 0 to the last quantifiable concentration of 129.6 and 752.0 microg x h/mL, respectively. After 7 days of 4, 20, or 100 mg/kg twice a day by gavage, plasma levels were 1300, 4900, and 5800 ng/mL and levels in the retina/choroid were 4800, 28 800, and 38 000 ng/g of tissue. CONCLUSIONS: Orally administered pazopanib has good bioavailability to the retina/choroid and strongly suppresses CNV in mice. Treatment with pazopanib after CNV is established causes dose-dependent regression of CNV. CLINICAL RELEVANCE: Pazopanib may be useful for treatment of CNV in humans.

Pharmacokinetics and brain penetration of casopitant, a potent and selective neurokinin-1 receptor antagonist, in the ferret.

The pharmacokinetics and brain penetration of the novel neurokinin (NK)-1 receptor antagonist casopitant [1-piperidinecarboxamide, 4-(4-acetyl-1-piperazinyl)-N-((1R)-1-(3,5-bis(trifluoromethyl)phenyl)ethyl)-2-(4-fluoro-2-methylphenyl)-N-methyl-, (2R,4S)-; GW679769] were examined in ferrets. The ferret is known to respond to the full spectrum of agents recognized to induce emesis in humans, and the cisplatin-induced emesis models in the ferret have been used to establish the antiemetic potential of casopitant. Following single i.p. dosing to the ferret, casopitant was rapidly absorbed, with plasma and brain concentrations being approximately equal at 2 h postdose. The predominant radioactive component present in the ferret brain after a single dose of [(14)C]casopitant was parent compound, accounting for approximately 76% of the radioactivity. The major metabolites present in brain tissue following administration of [(14)C]casopitant were hydroxylated casopitant (M1) and the corresponding ketone product of the M1 metabolite (M2), which accounted for approximately 19 and 3% of the radioactivity in the brain extracts, respectively. All three molecules had relatively similar potency against ferret brain cortical NK-1, suggesting that the pharmacologic activity of casopitant in the ferret is largely attributable to parent compound and, to a lesser extent, to its oxidative metabolites. Because casopitant is intended to be administered in combination with ondansetron and because therapeutic synergy has been observed with this combination in the ferret, a drug interaction study was conducted. The additional pharmacodynamic benefit of the combination dose was not because of an alteration in the pharmacokinetics of either agent but is likely the result of the complementary mechanisms of pharmacologic action of the two drugs.

The chemokine GRObeta mobilizes early hematopoietic stem cells characterized by enhanced homing and engraftment.

Mobilized peripheral blood hematopoietic stem cells (PBSCs) demonstrate accelerated engraftment compared with bone marrow; however, mechanisms responsible for enhanced engraftment remain unknown. PBSCs mobilized by GRObeta (GRObeta(Delta4)/CXCL2(Delta4)) or the combination of GRObeta(Delta4) plus granulocyte colony-stimulating factor (G-CSF) restore neutrophil and platelet recovery faster than G-CSF-mobilized PBSCs. To determine mechanisms responsible for faster hematopoietic recovery, we characterized immunophenotype and function of the GRObeta-mobilized grafts. PBSCs mobilized by GRObeta(Delta4) alone or with G-CSF contained significantly more Sca-1(+)-c-kit(+)-lineage(-) (SKL) cells and more primitive CD34(-)-SKL cells compared with cells mobilized by G-CSF and demonstrated superior competitive long-term repopulation activity, which continued to increase in secondary and tertiary recipients. GRObeta(Delta4)-mobilized SKL cells adhered better to VCAM-1(+) endothelial cells compared with G-CSF-mobilized cells. GRObeta(Delta4)-mobilized PBSCs did not migrate well to the chemokine stromal derived factor (SDF)-1alpha in vitro that was associated with higher CD26 expression. However, GRObeta(Delta4)-mobilized SKL and c-Kit(+) lineage(-) (KL) cells homed more efficiently to marrow in vivo, which was not affected by selective CXCR4 and CD26 antagonists. These data suggest that GRObeta(Delta4)-mobilized PBSCs are superior in reconstituting long-term hematopoiesis, which results from differential mobilization of early stem cells with enhanced homing and long-term repopulating capacity. In addition, homing and engraftment of GRObeta(Delta4)-mobilized cells is less dependent on the SDF-1alpha/CXCR4 axis.

Anti-emetic activity of ghrelin in ferrets exposed to the cytotoxic anti-cancer agent cisplatin.

Emesis may be modulated via multiple mechanisms. The actions of ghrelin suggest an ability to couple an induction of hunger with preparation of the stomach for ingestion of food. Such a process might reduce any tendency to vomit, so an anti-emetic activity of ghrelin was investigated in the ferret cisplatin-induced emesis model. In controls, intra-peritoneal cisplatin (10 mg/kg) induced 41.4+/-8.4 episodes of emesis comprising 310.4+/-55.3 retches and 28.8+/-6.9 vomits during the 6h observation; the latency to onset of the first emetic episode was 108.9+/-4.8 min. Intra-peritoneal ghrelin (1mg/kg, split as a 30 min pre- and 30 min-post dose) did not induce a change in behaviour or modify cisplatin-induced emesis (p>0.05). Intracerebroventricular (i.c.v.) administration (third ventricle) was achieved via a pre-implanted cannula. At the first emetic episode following cisplatin, ghrelin or vehicle (20 microl saline) was administered i.c.v. During the 30 min following the initial episode of emesis, control animals exhibited 18.0+/-2.6 emetic episodes comprising 160.3+/-24.1 retches and 13.8+/-2.7 vomits. Ghrelin 10 microg i.c.v. reduced the number of retches by 61.5% (p<0.05) and at a dose of 30 microg i.c.v. ghrelin reduced the number of episodes, individual retches and vomits by 74.4 (p<0.05), 80.4 (p<0.01), and 72.5% (p<0.05), respectively. At subsequent time periods there were no differences between ghrelin- or saline-treated animals (p>0.05). An ability of ghrelin to reduce emesis is consistent with a role in modulating gastro-intestinal functions and identifies a novel approach to the treatment of emesis.

The memory properties of cold-worked titanium rods in scoliosis constructs.

STUDY DESIGN: Time series monitoring changes in titanium and stainless steel rod curvature kept at a constant temperature of 37 C as a function of time. OBJECTIVES: To assess the possibility of loss of curvature in titanium rods after scoliosis surgery. SUMMARY OF BACKGROUND DATA: Titanium rods have gained use in scoliosis surgery due to their excellent biocompatibility, while allowing medical personnel to obtain undistorted magnetic resonance imaging scans following surgery. However, the impression of several clinicians has been that when screw pullout and/or loss of sagittal balance occurs, it may be due to the rods losing some of their curvature. METHODS: Five 6-mm rods of differing compositions and lengths (titanium 300 and 100 mm, stainless steel 300 and 100 mm, prebent titanium 85 mm) were bent at room temperature with a 3-point rod bender, then placed in an incubator at 37 C. Digital photographs were taken every 2 weeks and analyzed to extract the radius of curvature of each rod. RESULTS: The Ti rods had a significantly decreasing curvature with time. The prebent Ti and stainless steel rods did not exhibit significant change in curvature. CONCLUSIONS: Titanium rods bent at room temperature and then exposed to body temperature over time tend to exhibit "metal memory"; they gradually revert to their original shape. This may result in loss of sagittal balance and/or proximal screw pullout.

Effect of a selective and potent central nervous system penetrant, neurokinin-3 receptor antagonist (SB-222200), on cisplatin-induced emesis in the ferret.

The anti-emetic activity of selective NK-1 receptor antagonism is well established. However, little is known of the possibility that other NK receptors might also be involved in the emetic reflex. Given the reported location of NK-3 receptors within the rat brainstem vagal motor and sensory nuclei, we investigated the ability of SB-222200, a brain-penetrant NK-3 receptor antagonist, to interfere with emesis evoked in ferrets by the emetogenic cytotoxic agent cisplatin. In contrast to control anti-emetic experiments using the 5-HT3 receptor antagonist ondansetron, SB-222200 was found to have no effects on cisplatin-induced vomiting or on the associated reductions in feeding and drinking behaviors at any dose tested. We suggest that if NK-3 receptors are involved in the mechanisms of cisplatin-induced nausea and vomiting, they play only a minor role, relative to the major anti-emetic activity exhibited by 5-HT3 or NK-1 receptor antagonism.

Neutrophil-derived MMP-9 mediates synergistic mobilization of hematopoietic stem and progenitor cells by the combination of G-CSF and the chemokines GRObeta/CXCL2 and GRObetaT/CXCL2delta4.

Mobilized peripheral blood stem cells (PBSCs) are widely used for transplantation, but mechanisms mediating their release from marrow are poorly understood. We previously demonstrated that the chemokines GRObeta/CXCL2 and GRObetaT/CXCL2Delta4 rapidly mobilize PBSC equivalent to granulocyte colony-stimulating factor (G-CSF) and are synergistic with G-CSF. We now show that mobilization by GRObeta/GRObetaT and G-CSF, alone or in combination, requires polymorphonuclear neutrophil (PMN)-derived proteases. Mobilization induced by GRObeta/GRObetaT is associated with elevated levels of plasma and marrow matrix metalloproteinase 9 (MMP-9) and mobilization and MMP-9 are absent in neutrophil-depleted mice. G-CSF mobilization correlates with elevated neutrophil elastase (NE), cathepsin G (CG), and MMP-9 levels within marrow and is partially blocked by either anti-MMP-9 or the NE inhibitor MeOSuc-Ala-Ala-Pro-Val-CMK. Mobilization and protease accumulation are absent in neutrophil-depleted mice. Synergistic PBSC mobilization observed when G-CSF and GRObeta/GRObetaT are combined correlates with a synergistic rise in the level of plasma MMP-9, reduction in marrow NE, CG, and MMP-9 levels, and a coincident increase in peripheral blood PMNs but decrease in marrow PMNs compared to G-CSF. Synergistic mobilization is completely blocked by anti-MMP-9 but not MeOSuc-Ala-Ala-Pro-Val-CMK and absent in MMP-9-deficient or PMN-depleted mice. Our results indicate that PMNs are a common target for G-CSF and GRObeta/GRObetaT-mediated PBSC mobilization and, importantly, that synergistic mobilization by G-CSF plus GRObeta/GRObetaT is mediated by PMN-derived plasma MMP-9.