Direct Comparison of Peak Bulk Flow Rate of Programmable Intermittent Epidural Bolus and Manual Epidural Bolus Using a Closed-End Multiorifice Catheter: An Experimental Study.

BACKGROUND: The programmable intermittent epidural bolus (PIEB) has been popularized as the optimal delivery technique for labor analgesia. Suggested advantages of this method are less local anesthetic consumption, improved maternal satisfaction, potentially shorter duration of labor, and decreased workload requirements for the anesthesia providers. However, a manual bolus is still routinely used for breakthrough pain when the PIEB is underperforming. METHODS: We conducted a laboratory-based study to quantify the flow through a multiorifice epidural catheter using the PIEB setting on an epidural pump compared to the manual epidural bolus. Four syringe volumes, 3, 5, 10, and 20 mL, were selected for this experiment. The flow in a manual bolus was also studied with and without the presence of an epidural catheter filter. A generalized estimating equation analysis was done to compare data between the groups. RESULTS: Regardless of the syringe size, there was a several-fold increase in flow when a manual bolus was used compared to a pump-administered dose, with the highest difference in the peak flow rate observed in 3-mL boluses with up to a 12-fold difference, while the difference was, at most, 7-fold in 5-mL and 10-mL boluses. Manual boluses without a filter achieve a mean peak flow rate higher than manual boluses with a filter. CONCLUSIONS: Our study found that manual boluses produced a higher flow rate compared to the CADD-Solis epidural pump (Smiths Medical). This study also found that the placement of a particulate filter reduces the flow rates generated while bolusing. Bulk flow rate is directly correlated with induced pressure and solution spread. Because higher bolus pressure has been shown to provide a more efficient distribution of local anesthetic and more efficient pain relief, these results may have impactful clinical significance and will pave the way for future studies.

Partial blocking of mouse DSPP processing by substitution of Gly(451)-Asp(452) bond suggests the presence of secondary cleavage site(s).

Dentin sialophosphoprotein (DSPP) in the extracellular matrix of dentin is cleaved into dentin sialoprotein and dentin phosphoprotein, which originate from the NH(2)-terminal and COOH-terminal regions of DSPP, respectively. In the proteolytic processing of mouse DSPP, the peptide bond at Gly(451)-Asp(452) has been shown to be cleaved by bone morphogenetic protein 1 (BMP1)/Tolloid-like metalloproteinases. In this study, we generated transgenic mice expressing a mutant DSPP in which Asp(452) was substituted by Ala(452). Protein chemistry analyses of extracts from the long bone of these transgenic mice showed that the D452A substitution partially blocked DSPP processing in vivo. When the full-length form of mutant DSPP (designated "D452A-DSPP") isolated from the transgenic mice was treated with BMP1 in vitro, a portion of the D452A-DSPP was cleaved, suggesting the presence of secondary peptide bond(s) that can be broken by BMP1. To identify the potential secondary DSPP cleavage site(s), site-directed mutagenesis was performed to generate nine DNA constructs expressing DSPP-bearing substitutions at potential scission sites. These different types of mutant DSPP made in eukaryotic cell lines were treated with BMP1 and the digestion products were assessed by Western immunoblotting. All of the mutant DSPP molecular species were partially cleaved by BMP1, giving rise to a protein band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis similar to that of normal dentin sialoprotein. Taken together, we concluded that in addition to the peptide bond Gly(451)-Asp(452), there must be a cryptic cleavage site or sites close to Asp(452) in the mouse DSPP that can be cleaved by BMP1.

Failure to process dentin matrix protein 1 (DMP1) into fragments leads to its loss of function in osteogenesis.

Dentin matrix protein 1 (DMP1), an acidic protein important to the formation of bone and dentin, primarily exists as the processed NH(2)-terminal and COOH-terminal fragments in the extracellular matrix of the two tissues. Previous in vitro studies showed that the substitution of residue Asp(213) by Ala(213) (D213A) at a cleavage site blocked the processing of mouse DMP1 in cells. In this study, we generated transgenic mice expressing mutant D213A-DMP1 (WT/D213A-Tg mice) to test the hypothesis that the proteolytic processing of DMP1 is an activation step essential to osteogenesis. By crossbreeding WT/D213A-Tg mice with Dmp1 knock-out (Dmp1-KO) mice, we obtained mice expressing D213A-DMP1 in a Dmp1-KO background; these mice will be referred to as "Dmp1-KO/D213A-Tg" mice. Biochemical, radiological, and morphological approaches were used to characterize the skeletal phenotypes of Dmp1-KO/D213A-Tg mice compared with wild-type mice, Dmp1-KO mice, and Dmp1-KO mice expressing the normal Dmp1 transgene. Protein chemistry analyses showed that DMP1 was barely cleaved in the bone of the Dmp1-KO/D213A-Tg mice, indicating that D213A substitution effectively blocked the proteolytic processing of DMP1 in vivo. While the expression of the normal Dmp1 transgene completely rescued the phenotypic skeletal changes of the Dmp1-KO mice, the expression of the mutant D213A-Dmp1 transgene failed to do so. These results indicate that the full-length form of DMP1 is an inactive precursor and its proteolytic processing is an activation step essential to the biological functions of this protein in osteogenesis.

Dentin sialophosphoprotein in biomineralization.

Two of the proteins found in significant quantity in the extracellular matrix (ECM) of dentin are dentin phosphoprotein (DPP) and dentin sialoprotein (DSP). DPP, the most abundant of the noncollagenous proteins (NCPs) in dentin is an unusually polyanionic protein, containing a large number of aspartic acids (Asp) and phosphoserines (Pse) in the repeating sequences of (Asp-Pse)(n). and (Asp-Pse-Pse)(n). The many negatively charged regions of DPP are thought to promote mineralization by binding calcium and presenting it to collagen fibers at the mineralization front during the formation of dentin. This purported role of DPP is supported by a sizeable pool of in vitro mineralization data showing that DPP is an important initiator and modulator for the formation and growth of hydroxyapatite (HA) crystals. Quite differently, DSP is a glycoprotein, with little or no phosphate. DPP and DSP are the cleavage products of dentin sialophosphoprotein (DSPP). Human and mouse genetic studies have demonstrated that mutations in, or knockout of, the Dspp gene result in mineralization defects in dentin and/or bone. The discoveries in the past 40 years with regard to DPP, DSP, and DSPP have greatly enhanced our understanding of biomineralization and set a new stage for future studies. In this review, we summarize the important and new developments made in the past four decades regarding the structure and regulation of the Dspp gene, the biochemical characteristics of DSPP, DPP, and DSP as well as the cell/tissue localizations and functions of these molecules.

Mechanical, topographical and chemical cues combined with physical therapy for peripheral nerve injuries.

Aim: The aim of this paper is to evaluate biomaterial cues combined with physical therapy (PT) on functional recovery in a rat sciatic nerve injury model. Materials & methods: Nerve growth conduits were filled with longitudinally aligned hyaluronic acid fibers and microspheres containing neurotrophic factor (growth factor [GF]). All animals received behavior and functional testing throughout the study, which concluded with measurement of compound muscle action potentials and contractile force of the gastrocnemius muscle. Results & conclusion: Including GF improved recovery of gross motor function and increased sensory pain sensation. During the 4 weeks that animals participated in PT, these groups showed higher static sciatic index scores. Including GF and PT has the potential to improve clinical outcomes following peripheral nerve injury.

Expression of dentin sialophosphoprotein in non-mineralized tissues.

Dentin sialophosphoprotein (DSPP) and its cleaved products, dentin phosphoprotein (DPP) and dentin sialoprotein (DSP), play important roles in biomineralization. Believed to be tooth specific, the authors' group revealed its expression in bone, and more recently, they and other groups also showed its expression in a few types of soft tissues. In this study, the authors systematically examined the expression of DSPP in a variety of non-mineralized tissues using reverse-transcription polymerase chain reaction (RT-PCR), real-time PCR, Western immunoblotting, and immunohistochemistry analyses in wild-type mice as well as ß-galactosidase assays in the Dspp lacZ knock-in mice. These approaches showed the presence of DSPP in the salivary glands, cartilage, liver, kidney, and brain and its absence in the heart and spleen. Real-time PCR showed that the expression levels of DSPP mRNA in salivary glands, cartilage, liver, and kidney were higher than in the bone. Interestingly, DSPP was observed in the pericytes of blood vessels in the dental pulp, which are believed to be able to differentiate into odontoblasts. On the basis of these observations, the authors conclude that DSPP and/or its cleaved products may fulfill important functions in certain non-mineralized tissues in addition to its role in biomineralization.

Expression of FAM20C in the osteogenesis and odontogenesis of mouse.

Mutations in FAM20C were recently identified as the cause of lethal osteosclerotic bone dysplasia, which highlighted the important role of this molecule in biomineralization. No systematic studies have been performed to evaluate the expression pattern of this relatively new molecule in the developmental processes of bone and tooth. In the present study, we analyzed in detail the expression profile of FAM20C during osteogenesis and odontogenesis using ISH and IHC approaches. The specimens analyzed were mouse tissues spanning embryonic day 13.5 (E13.5) to postnatal 8 weeks. The earliest presence of FAM20C was observed at E14.5. During osteogenesis, FAM20C mRNA was detected in the chondrocytes and osteoblasts of the long bone, whereas its protein was observed in the extracellular matrix (ECM) of bone and in the cytoplasm of the chondrocytes, osteoblasts, and osteocytes. During odontogenesis, FAM20C mRNA was detected in the ameloblasts, odontoblasts, cementoblasts, and periodontal ligament fibroblasts, whereas its protein was observed in the matrices of dentin, enamel, and alveolar bone and in the cytoplasm of the aforementioned cells. The temporospatial expression profile revealed in this study indicates that FAM20C is an ECM protein that may play an important role in controlling the mineralization of bone and tooth.

Molecular genetic characterization of tamoxifen-associated endometrial cancer.

OBJECTIVES: The non-steroidal, selective estrogen receptor modulator tamoxifen is currently the most extensively used hormonal agent for the prevention and treatment of estrogen receptor-positive breast cancer. Epidemiologic studies and clinical trials have shown an increased risk of endometrial cancer with tamoxifen exposure; however, few studies have examined these tumors on a molecular level. We sought to elucidate the molecular genetic alterations found in tamoxifen-associated endometrial cancer. METHODS: Twenty-nine breast cancer patients with a history of tamoxifen use who subsequently developed endometrial cancer were retrospectively identified and matched for endometrial histologic subtype and grade to 29 endometrial cancers from breast cancer patients never exposed to tamoxifen. Endometrial tumor tissue was microdissected and genomic DNA extracted for each case. Direct DNA sequencing of the most commonly mutated genes in sporadic endometrial cancer, PTEN, K-RAS, TP53, and CTNNB1, was performed in addition to microsatellite instability (MI) studies. Fisher's Exact Test was utilized for statistical analyses. RESULTS: Of 29 tamoxifen-associated cancers, 10 (34.5%) contained PTEN mutations compared to 13 (44.8%) of the non-tamoxifen-associated cancers (P = 0.59). All PTEN mutations were found in tumors with endometrioid histology, reflecting what is seen in sporadic endometrial cancers. Mutations of K-RAS, TP53, and microsatellite instability were present in similar frequencies between the two breast cancer groups, and moreover, these were similar to mutational frequencies found in sporadic endometrial cancer. CONCLUSION: Tamoxifen and non-tamoxifen-associated endometrial carcinomas arising in women with breast cancer contain similar genetic alterations to those of sporadic endometrial carcinomas.

Costs of treatment and outcomes associated with second-line therapy and greater for relapsed ovarian cancer.

OBJECTIVES: Most women with epithelial ovarian cancer (EOC) will develop disease progression or recurrence with resistance to platinum therapy. We report overall costs and treatment outcomes associated with topotecan or gemcitabine administration in platinum- and paclitaxel-resistant EOC patients. METHODS: Patients who received topotecan (n = 51) or gemcitabine (n = 56) as second-line therapy or greater for platinum- and paclitaxel-resistant EOC were retrospectively identified. Per patient costs for each regimen were determined and compared. RESULTS: The mean total direct cost per cycle per patient of gemcitabine was $2732.28, with a median total direct cost per cycle of $1382.73. The mean total direct cost per cycle per patient of topotecan was $7832.07, with a median total direct cost per cycle of $4219.02. By comparison of the means, total direct cost per cycle per patient was significantly more expensive for topotecan (P = 0.001). Fifty-six patients received a total of 415 cycles of gemcitabine, median 5 cycles per patient (range, 1-59). Thirteen (23.2%; 95% CI, 11.9-34.5%) of 56 patients displayed clinical benefit, with median PFS of 1.8 months and median overall survival (OS) of 8.2 months. Fifty-one patients received topotecan, for a total of 264 cycles, median 4 cycles per patient (range, 1-42). Twenty-eight (56%; 95% CI, 42.0-70.0%) of 50 patients achieved clinical benefit, with PFS and OS medians of 3.6 and 16.8 months, respectively. CONCLUSIONS: Gemcitabine and topotecan are active agents in heavily pretreated, platinum- and paclitaxel-resistant EOC patients. Topotecan was more costly to deliver. Although a larger percentage of patients received clinical benefit with topotecan use, this likely reflects physician selection for use of topotecan earlier in the course of disease.

Cervical spine geometry in the automotive seated posture: variations with age, stature, and gender.

In the mid 1970s, UMTRI investigated the biomechanical properties of the head and neck using 180 "normal" adult subjects selected to fill eighteen subject groups based on age (young, mid-aged, older), gender, and stature (short, medium, and tall by gender). Lateral-view radiographs of the subjects' cervical spines and heads were taken with the subjects seated in a simulated automotive neutral posture, as well as with their necks in full-voluntary flexion and full-voluntary extension. Although the cervical spine and lower head geometry were previously measured manually and documented, new technologies have enabled computer digitization of the scanned x-ray images and a more comprehensive and detailed analysis of the variation in cervical spine and lower head geometry with subject age, stature, and gender. After scanning the radiographic images, 108 skeletal landmarks on the cervical vertebrae and 10 head landmarks were digitized. The resulting database of cervical spine and head geometry was used to study cervical spine curvature, vertebral dimensions, and head/neck orientation as functions of age, gender, and stature. The data were used to characterize neutral posture cervical spine curvatures using two methods: a curvature index and Bézier spline functions. Lateral-view vertebral dimensions were also calculated for each subject, and a cascading series of equations was developed to estimate vertebral size and shape for a selected age, stature, and gender. The orientation of the cervical spine was defined using a neck chord angle, where the neck chord was varied to use different anatomical landmarks and estimates of joint centers for the top and bottom of the neck chord. Results from the study have been incorporated into a MS-Access based software package that allows researchers and modelers to generate cervical spine geometries for occupants of a specified age, gender, and stature. The program allows selection of individual occupants from the database that meet age, stature, gender, or curvature criteria, or creation of a composite cervical spine geometry representative of the selected age, gender, and stature. This tool will allow researchers to configure and vary cervical spine geometry in computer models and experimental test setups used to study head and neck impact response and injury risk.