Evaluating the influence of marine protected areas on surf zone fish

Marine protected areas (MPAs) globally serve conservation and fisheries management goals, generating positive effects in some marine ecosystems. Surf zones and sandy beaches, critical ecotones bridging land and sea, play a pivotal role in the life cycles of numerous fish species and serve as prime areas for subsistence and recreational fishing. Despite their significance, these areas remain understudied when evaluating the effects of MPAs. We compared surf zone fish assemblages inside and outside MPAs across 3 bioregions in California (USA). Using seines and baited remote underwater videos (BRUVs), we found differences in surf zone fish inside and outside MPAs in one region. Inside south region MPAs, we observed higher abundance (Tukey's honest significant difference [HSD] = 0.83, p = 0.0001) and richness (HSD = 0.22, p = 0.0001) in BRUVs and greater biomass (HSD = 0.32, p = 0.0002) in seine surveys compared with reference sites. Selected live-bearing, fished taxa were positively affected by MPAs. Elasmobranchs displayed greater abundance in BRUV surveys and higher biomass in seine surveys inside south region MPAs (HSD = 0.35, p = 0.0003 and HSD = 0.23, p = 0.008, respectively). Although we observed no overall MPA signal for Embiotocidae, abundances of juvenile and large adult barred surfperch (Amphistichus argenteus), the most abundant fished species, were higher inside MPAs (K-S test D = 0.19, p < 0.0001). Influence of habitat characteristics on MPA performance indicated surf zone width was positively associated with fish abundance and biomass but negatively associated with richness. The south region had the largest positive effect size on all MPA performance metrics. Our findings underscored the variability in species richness and composition across regions and survey methods that significantly affected differences observed inside and outside MPAs. A comprehensive assessment of MPA performance should consider specific taxa, their distribution, and the effects of habitat factors and geography.

Targeting cell surface glycans with lectin-coated fluorescent nanodiamonds

Glycosylation is arguably the most important functional post-translational modification in brain cells and abnormal cell surface glycan expression has been associated with neurological diseases and brain cancers. In this study we developed a novel method for uptake of fluorescent nanodiamonds (FND), carbon-based nanoparticles with low toxicity and easily modifiable surfaces, into brain cell subtypes by targeting their glycan receptors with carbohydrate-binding lectins. Lectins facilitated uptake of 120 nm FND with nitrogen-vacancy centers in three types of brain cells - U87-MG astrocytes, PC12 neurons and BV-2 microglia cells. The nanodiamond/lectin complexes used in this study target glycans that have been described to be altered in brain diseases including sialic acid glycans via wheat (Triticum aestivum) germ agglutinin (WGA), high mannose glycans via tomato (Lycopersicon esculentum) lectin (TL) and core fucosylated glycans via Aleuria aurantia lectin (AAL). The lectin conjugated nanodiamonds were taken up differently by the various brain cell types with fucose binding AAL/FNDs taken up preferentially by glioblastoma phenotype astrocyte cells (U87-MG), sialic acid binding WGA/FNDs by neuronal phenotype cells (PC12) and high mannose binding TL/FNDs by microglial cells (BV-2). With increasing recognition of glycans having a role in many diseases, the lectin bioconjugated nanodiamonds developed here are well suited for further investigation into theranostic applications.

Simultaneous super-linear excitation-emission and emission depletion allows imaging of upconversion nanoparticles with higher sub-diffraction resolution

Upconversion nanoparticles (UCNPs) are becoming increasingly popular as biological markers as they offer photo-stable imaging in the near-infrared (NIR) biological transparency window. Imaging at NIR wavelengths benefits from low auto-fluorescence background and minimal photo-damage. However, as the diffraction limit increases with the wavelength, the imaging resolution deteriorates. To address this limitation, recently two independent approaches have been proposed for imaging UCNPs with sub-diffraction resolution, namely stimulated emission-depletion (STED) microscopy and super linear excitation-emission (uSEE) microscopy. Both methods are very sensitive to the UCNP composition and the imaging conditions, i.e. to the excitation and depletion power. Here, we demonstrate that the imaging conditions can be chosen in a way that activates both super-resolution regimes simultaneously when imaging NaYF₄:Yb,Tm UCNPs. The combined uSEE-STED mode benefits from the advantages of both techniques, allowing for imaging with lateral resolution about six times better than the diffraction limit due to STED and simultaneous improvement of the axial resolution about twice over the diffraction limit due to uSEE. Conveniently, at certain imaging conditions, the uSEE-STED modality can achieve better resolution at four times lower laser power compared to STED mode, making the method appealing for biological applications. We illustrate this by imaging UCNPs functionalized by colominic acid in fixed neuronal phenotype cells.

Lipopolysaccharide and Morphine-3-Glucuronide-Induced Immune Signalling Increases the Expression of Polysialic Acid in PC12 Cells

Polysialic acid (polySia), a long homopolymer of 2,8-linked sialic acids, is abundant in the embryonic brain and is restricted largely in adult brain to regions that exhibit neurogenesis and structural plasticity. In the central nervous system (CNS), polySia is highly important for cell-cell interactions, differentiation, migration and cytokine responses, which are critical neuronal functions regulating intercellular interactions that underlie immune signalling in the CNS. In recent reports, a metabolite of morphine, morphine-3-glucuronide (M3G), has been shown to cause immune signalling in the CNS. In this study, we compared the effects of neurite growth factor (NGF), lipopolysaccharide (LPS) and M3G exposure on the expression of polySia in PC12 cells using immunocytochemistry and Western blot analysis. PolySia was also extracted from stimulated cell proteins by endo-neuraminidase digestion and quantitated using fluorescent labelling followed by HPLC analysis. PolySia expression was significantly increased following NGF, M3G or LPS stimulation when compared with unstimulated cells or cells exposed to the TLR4 antagonist LPS-RS. Additionally, we analyzed the effects of test agent exposure on cell migration and the oxidative stress response of these cells in the presence and absence of polySia expression on their cell surface. We observed an increase in oxidative stress in cells without polySia as well as following M3G or LPS stimulation. Our study provides evidence that polySia expression in neuronal-like PC12 cells is influenced by M3G and LPS exposure alike, suggestive of a role of TLR4 in triggering these events.

A Nanoparticle-Based Affinity Sensor that Identifies and Selects Highly Cytokine-Secreting Cells

We developed a universal method termed OnCELISA to detect cytokine secretion from individual cells by applying a capture technology on the cell membrane. OnCELISA uses fluorescent magnetic nanoparticles as assay reporters that enable detection on a single-cell level in microscopy and flow cytometry and fluorimetry in cell ensembles. This system is flexible and can be modified to detect different cytokines from a broad range of cytokine-secreting cells. Using OnCELISA we have been able to select and sort highly cytokine-secreting cells and identify cytokine-secreting expression profiles of different cell populations in vitro and ex vivo. We show that this system can be used for ultrasensitive monitoring of cytokines in the complex biological environment of atherosclerosis that contains multiple cell types. The ability to identify and select cell populations based on their cytokine expression characteristics is valuable in a host of applications that require the monitoring of disease progression.

The effect of particle size on nanodiamond fluorescence and colloidal properties in biological media

Fluorescent nanodiamonds (FNDs) are extremely photostable markers and nanoscale sensors, which are increasingly used in biomedical applications. Nanoparticle size is a critical parameter in the majority of these applications. Yet, the effect of particle size on FND's fluorescence and colloidal properties is not well understood today. Here, we investigate the fluorescence and colloidal stability of commercially available high-pressure high-temperature FNDs containing nitrogen-vacancy (NV) centers in biological media. Unconjugated FNDs in sizes ranging between 10 nm and 140 nm with an oxidized surface are studied using dynamic light scattering and fluorescence spectroscopy. We determine their colloidal stability in water, fetal bovine serum, Dulbecco's Modified Eagle Medium and complete media. The FNDs' relative fluorescence brightness, the NV charge-state, and the FND fluorescence against media autofluorescence are analyzed as a function of FND size. Our results will enable researchers in biology and beyond to identify the most promising FND particle size for their application.

3D sub-diffraction imaging in a conventional confocal configuration by exploiting super-linear emitters

Sub-diffraction microscopy enables bio-imaging with unprecedented clarity. However, most super-resolution methods require complex, costly purpose-built systems, involve image post-processing and struggle with sub-diffraction imaging in 3D. Here, we realize a conceptually different super-resolution approach which circumvents these limitations and enables 3D sub-diffraction imaging on conventional confocal microscopes. We refer to it as super-linear excitation-emission (SEE) microscopy, as it relies on markers with super-linear dependence of the emission on the excitation power. Super-linear markers proposed here are upconversion nanoparticles of NaYF4, doped with 20% Yb and unconventionally high 8% Tm, which are conveniently excited in the near-infrared biological window. We develop a computational framework calculating the 3D resolution for any viable scanning beam shape and excitation-emission probe profile. Imaging of colominic acid-coated upconversion nanoparticles endocytosed by neuronal cells, at resolutions twice better than the diffraction limit both in lateral and axial directions, illustrates the applicability of SEE microscopy for sub-cellular biology.

Visualizing neuroinflammation with fluorescence and luminescent lanthanide-based in situ hybridization

BACKGROUND

Neurokine signaling via the release of neurally active cytokines arises from glial reactivity and is mechanistically implicated in central nervous system (CNS) pathologies such as chronic pain, trauma, neurodegenerative diseases, and complex psychiatric illnesses. Despite significant advancements in the methodologies used to conjugate, incorporate, and visualize fluorescent molecules, imaging of rare yet high potency events within the CNS is restricted by the low signal to noise ratio experienced within the CNS. The brain and spinal cord have high cellular autofluorescence, making the imaging of critical neurokine signaling and permissive transcriptional cellular events unreliable and difficult in many cases.

METHODS

In this manuscript, we developed a method for background-free imaging of the transcriptional events that precede neurokine signaling using targeted mRNA transcripts labeled with luminescent lanthanide chelates and imaged via time-gated microscopy. To provide examples of the usefulness this method can offer to the field, the mRNA expression of toll-like receptor 4 (TLR4) was visualized with traditional fluorescent in situ hybridization (FISH) or luminescent lanthanide chelate-based in situ hybridization (LISH) in mouse BV2 microglia or J774 macrophage phenotype cells following lipopolysaccharide stimulation. TLR4 mRNA staining using LISH- and FISH-based methods was also visualized in fixed spinal cord tissues from BALB/c mice with a chronic constriction model of neuropathic pain or a surgical sham model in order to demonstrate the application of this new methodology in CNS tissue samples.

RESULTS

Significant increases in TLR4 mRNA expression and autofluorescence were visualized over time in mouse BV2 microglia or mouse J774 macrophage phenotype cells following lipopolysaccharide (LPS) stimulation. When imaged in a background-free environment with LISH-based detection and time-gated microscopy, increased TLR4 mRNA was observed in BV2 microglia cells 4 h following LPS stimulation, which returned to near baseline levels by 24 h. Background-free imaging of mouse spinal cord tissues with LISH-based detection and time-gated microscopy demonstrated a high degree of regional TLR4 mRNA expression in BALB/c mice with a chronic constriction model of neuropathic pain compared to the surgical sham model.

CONCLUSIONS

Advantages offered by adopting this novel methodology for visualizing neurokine signaling with time-gated microscopy compared to traditional fluorescent microscopy are provided.

The effect of streptozotocin-induced hyperglycemia on N-and O-linked protein glycosylation in mouse ovary

Post-translational modification of proteins namely glycosylation influences cellular behavior, structural properties and interactions including during ovarian follicle development and atresia. However, little is known about protein glycosylation changes occurring in diabetes mellitus in ovarian tissues despite the well-known influence of diabetes on the outcome of successful embryo implantation. In our study, the use of PGC chromatography-ESI mass spectrometry in negative ion mode enabled the identification of 138 N-glycans and 6 O-glycans on the proteins of Streptozotocin-induced (STZ) diabetic mouse ovarian tissues (n = 3). Diabetic mouse ovaries exhibited a relative decrease in sialylation, fucosylation and, to a lesser extent, branched N-linked glycan structures, as well as an increase in oligomannose structures on their proteins, compared with nondiabetic mouse ovaries. Changes in N-glycans occurred in the diabetic liver tissue but were more evident in diabetic ovarian tissue of the same mouse, suggesting an organ-specific effect of diabetes mellitus on protein glycosylation. Although at a very low amount, O-GalNAc glycans of mice ovaries were present as core type 1 and core type 2 glycans; with a relative increase in the NeuGc:NeuAc ratio as the most significant difference between control and diabetic ovarian tissues. STZ-treated mice also showed a trend towards an increase in TNF-α and IL1-B inflammatory cytokines, which have previously been shown to influence protein glycosylation.

Influence of surface chemistry on the formation of a protein corona on nanodiamonds

The protein corona of nanodiamonds is dominated by low molecular weight proteins and is largely independent of surface chemistry. The pre-incubation of nanodiamonds in serum and the formation of a protein corona decrease the production of reactive oxygen species, increasing the cell viability of macrophages.

Behavioral sensitization to methamphetamine induces specific interneuronal mRNA pathology across the prelimbic and orbitofrontal cortices

Schizophrenia is associated with significant pathophysiological changes to interneurons within the prefrontal cortex (PFC), with mRNA and protein changes associated with the GABA network localized to specific interneuron subtypes. Methamphetamine is a commonly abused psychostimulant that can induce chronic psychosis and symptoms that are similar to schizophrenia, suggesting that chronic METH induced psychosis may be associated with similar brain pathology to schizophrenia in the PFC. The aim of this study, therefore, was to examine mRNA expression of interneuron markers across two regions of the PFC (prelimbic (PRL) and orbitofrontal cortices (OFC)) following METH sensitization, an animal model of METH psychosis. We also studied the association between GABA mRNA expression and interneuronal mRNA expression to identify whether particular changes to the GABA network could be localized to a specific inhibitory cellular phenotype. METH sensitization increased the transcriptional expression of calbindin, calretinin, somatostatin, cholecyctokinin and vasoactive intestinal peptide in the PRL while parvalbumin, calbindin, cholectokinin and vasoactive intestinal peptide were upregulated in the OFC. Based on our previous findings, we also found significant correlations between GAD₆₇, GAT₁ and parvalbumin while GAD₆₇, GAD₆₅ and GAT₁ were positively correlated with cholecystokinin in the PRL of METH sensitized rats. Within the OFC, the expression of GABA_Aα1 was positively correlated with somatostatin while GABA_Aα5 was negatively associated with somatostatin and calbindin. These findings suggest that METH sensitization differentially changes the expression of mRNAs encoding for multiple peptides and calcium binding proteins across the PRL and the OFC. Furthermore, these findings support that changes to the GABA network may also occur within specific cell types. These results, therefore, provide the first evidence that METH sensitization mediates differential interneuronal pathology across the PRL and OFC and such changes could have profound consequences on behavior and cognitive output.

Neurochemistry of neurons in the ventrolateral medulla activated by hypotension: Are the same neurons activated by glucoprivation?

Previous studies have demonstrated that a range of stimuli activate neurons, including catecholaminergic neurons, in the ventrolateral medulla. Not all catecholaminergic neurons are activated and other neurochemical content is largely unknown hence whether stimulus specific populations exist is unclear. Here we determine the neurochemistry (using in situ hybridization) of catecholaminergic and noncatecholaminergic neurons which express c-Fos immunoreactivity throughout the rostrocaudal extent of the ventrolateral medulla, in Sprague Dawley rats treated with hydralazine or saline. Distinct neuronal populations containing PPCART, PPPACAP, and PPNPY mRNAs, which were largely catecholaminergic, were activated by hydralazine but not saline. Both catecholaminergic and noncatecholaminergic neurons containing preprotachykinin and prepro-enkephalin (PPE) mRNAs were also activated, with the noncatecholaminergic population located in the rostral C1 region. Few GlyT2 neurons were activated. A subset of these data was then used to compare the neuronal populations activated by 2-deoxyglucose evoked glucoprivation (Brain Structure and Function (2015) 220:117). Hydralazine activated more neurons than 2-deoxyglucose but similar numbers of catecholaminergic neurons. Commonly activated populations expressing PPNPY and PPE mRNAs were defined. These likely include PPNPY expressing catecholaminergic neurons projecting to vasopressinergic and corticotrophin releasing factor neurons in the paraventricular nucleus, which when activated result in elevated plasma vasopressin and corticosterone. Stimulus specific neurons included noncatecholaminergic neurons and a few PPE positive catecholaminergic neuron but neurochemical codes were largely unidentified. Reasons for the lack of identification of stimulus specific neurons, readily detectable using electrophysiology in anaesthetized preparations and for which neural circuits can be defined, are discussed.

Chronic Methamphetamine Self-Administration Dysregulates Oxytocin Plasma Levels and Oxytocin Receptor Fibre Density in the Nucleus Accumbens Core and Subthalamic Nucleus of the Rat

The neuropeptide oxytocin attenuates reward and abuse for the psychostimulant methamphetamine (METH). Recent findings have implicated the nucleus accumbens (NAc) core and subthalamic nucleus (STh) in oxytocin modulation of acute METH reward and relapse to METH-seeking behaviour. Surprisingly, the oxytocin receptor (OTR) is only modestly involved in both regions in oxytocin attenuation of METH-primed reinstatement. Coupled with the limited investigation of the role of the OTR in psychostimulant-induced behaviours, we primarily investigated whether there are cellular changes to the OTR in the NAc core and STh, as well as changes to oxytocin plasma levels, after chronic METH i.v. self-administration (IVSA) and after extinction of drug-taking. An additional aim was to examine whether changes to central corticotrophin-releasing factor (CRF) and plasma corticosterone levels were also apparent because of the interaction of oxytocin with stress-regulatory mechanisms. Male Sprague-Dawley rats were trained to lever press for i.v. METH (0.1 mg/kg/infusion) under a fixed-ratio 1 schedule or received yoked saline infusions during 2-h sessions for 20 days. An additional cohort of rats underwent behavioural extinction for 15 days after METH IVSA. Subsequent to the last day of IVSA or extinction, blood plasma was collected for enzyme immunoassay, and immunofluorescence was conducted on NAc core and STh coronal sections. Rats that self-administered METH had higher oxytocin plasma levels, and decreased OTR-immunoreactive (-IR) fibres in the NAc core than yoked controls. In animals that self-administered METH and underwent extinction, oxytocin plasma levels remained elevated, OTR-IR fibre density increased in the STh, and a trend towards normalisation of OTR-IR fibre density was evident in the NAc core. CRF-IR fibre density in both brain regions and corticosterone plasma levels did not change across treatment groups. These findings demonstrate that oxytocin systems, both centrally within the NAc core and STh, as well as peripherally through plasma measures, are dysregulated after METH abuse.

GABAergic mRNA expression is upregulated in the prefrontal cortex of rats sensitized to methamphetamine

Inhibitory gamma-aminobutyric acid (GABA)-mediated neurotransmission plays an important role in the regulation of the prefrontal cortex (PFC), with increasing evidence suggesting that dysfunctional GABAergic processing of the PFC may underlie certain deficits reported across psychotic disorders. Methamphetamine (METH) is a psychostimulant that induces chronic psychosis in a subset of users, with repeat administration producing a progressively increased vulnerability to psychotic relapse following subsequent drug administration (sensitization). The aim here was to investigate changes to GABAergic mRNA expression in the PFC of rats sensitized to METH using quantitative polymerase chain reaction (qPCR). Male Sprague-Dawley rats (n=12) underwent repeated methamphetamine (intraperitoneal (i.p.) or saline injections for 7 days. Following 14 days of withdrawal, rats were challenged with acute methamphetamine (1mg/kg i.p.) and RNA was isolated from the PFC to compare the relative mRNA expression of a range of GABA enzymes, transporters and receptors subunits. METH challenge resulted in a significant sensitized behavioral (locomotor) response in METH pre-treated animals compared with saline pre-treated controls. The mRNAs of transporters (GAT1 and GAT3), ionotropic GABAA receptor subunits (α3 and β1), together with the metabotropic GABAB1 receptor, were upregulated in the PFC of sensitized rats compared with saline controls. These findings indicate that GABAergic mRNA expression is significantly altered at the pre and postsynaptic level following sensitization to METH, with sensitization resulting in the transcriptional upregulation of several inhibitory genes. These changes likely have significant consequences on GABA-mediated neurotransmission in the PFC and may underlie certain symptoms conserved across psychotic disorders, such as executive dysfunction.

Proteome Analysis of Ground State Pluripotency

The differentiation potential of pluripotent embryonic stem cells (ESCs) can be manipulated via serum and medium conditions for direct cellular development or to maintain a naïve ground state. The self-renewal state of ESCs can thus be induced by adding inhibitors of mitogen activated protein kinase (MAPK) and glycogen synthase kinase-3 (Gsk3), known as 2 inhibitors (2i) treatment. We have used a shotgun proteomics approach to investigate differences in protein expressions between 2i- and serum-grown mESCs. The results indicated that 164 proteins were significantly upregulated and 107 proteins downregulated in 2i-grown cells compared to serum. Protein pathways in 2i-grown cells with the highest enrichment were associated with glycolysis and gluconeogenesis. Protein pathways related to organ development were downregulated in 2i-grown cells. In serum-grown ESCs, protein pathways involved in integrin and focal adhesion, and signaling proteins involved in the actin cytoskeleton regulation were enriched. We observed a number of nuclear proteins which were mostly involved in self-renewal maintenance and were expressed at higher levels in 2i compared to serum - Dnmt1, Map2k1, Parp1, Xpo4, Eif3g, Smarca4/Brg1 and Smarcc1/Baf155. Collectively, the results provided an insight into the key protein pathways used by ESCs in the ground state or metastable conditions through 2i or serum culture medium, respectively.

Somatostatin 2a receptors are not expressed on functionally identified respiratory neurons in the ventral respiratory column of the rat

Microinjection of somatostatin (SST) causes site-specific effects on respiratory phase transition, frequency, and amplitude when microinjected into the ventrolateral medulla (VLM) of the anesthetized rat, suggesting selective expression of SST receptors on different functional classes of respiratory neurons. Of the six subtypes of SST receptor, somatostatin 2a (sst2a ) is the most prevalent in the VLM, and other investigators have suggested that glutamatergic neurons in the preBötzinger Complex (preBötC) that coexpress neurokinin-1 receptor (NK1R), SST, and sst2a are critical for the generation of respiratory rhythm. However, quantitative data describing the distribution of sst2a in respiratory compartments other than preBötC, or on functionally identified respiratory neurons, is absent. Here we examine the medullary expression of sst2a with particular reference to glycinergic/expiratory neurons in the Bötzinger Complex (BötC) and NK1R-immunoreactive/inspiratory neurons in the preBötC. We found robust sst2a expression at all rostrocaudal levels of the VLM, including a large proportion of catecholaminergic neurons, but no colocalization of sst2a and glycine transporter 2 mRNA in the BötC. In the preBötC 54% of sst2a -immunoreactive neurons were also positive for NK1R. sst2a was not observed in any of 52 dye-labeled respiratory interneurons, including seven BötC expiratory-decrementing and 11 preBötC preinspiratory neurons. We conclude that sst2a is not expressed on BötC respiratory neurons and that phasic respiratory activity is a poor predictor of sst2a expression in the preBötC. Therefore, sst2a is unlikely to underlie responses to BötC SST injection, and is sparse or absent on respiratory neurons identified by classical functional criteria. J. Comp. Neurol. 524:1384-1398, 2016. © 2015 Wiley Periodicals, Inc.

Regional changes in cardiac and stellate ganglion norepinephrine transporter in DOCA-salt hypertension

Uptake of norepinephrine via the neuronal norepinephrine transporter is reduced in the heart during deoxycorticosterone (DOCA)-salt hypertension. We hypothesized that this was due to reduced norepinephrine transporter mRNA and/or protein expression in the stellate ganglia and heart. After 4 weeks of DOCA-salt treatment there was no change in norepinephrine transporter mRNA in either the right or the left stellate ganglia from hypertensive rats (n=5-7, p>0.05). Norepinephrine transporter immunoreactivity in the left stellate ganglion was significantly increased (n=4, p<0.05) while the right stellate ganglion was unchanged (n=4, p>0.05). Whole heart norepinephrine content was significantly reduced in DOCA rats consistent with reduced uptake function; however, when norepinephrine was assessed by chamber, a significant decrease was noted only in the right atrium and right ventricle (n=6, p<0.05). Cardiac norepinephrine transport binding by chamber revealed that it was only reduced in the left atrium (n=5-7, p>0.05). Therefore, 1) contrary to our hypothesis reduced reuptake in the hypertensive heart is not exclusively due to an overall reduction in norepinephrine transporter mRNA or protein in the stellate ganglion or heart, and 2) norepinephrine transporter regulation occurs regionally in the heart and stellate ganglion in the hypertensive rat heart.

Distribution and localisation of Gα proteins in the rostral ventrolateral medulla of normotensive and hypertensive rats: focus on catecholaminergic neurons

About 860 G-protein-coupled receptors (GPCRs) mediate their actions via heterotrimeric G-proteins. Their activation releases Gα from Gβλ subunits. The type of Gα subunit dictates the major signalling proteins involved: adenylyl cyclase, PLC and rhoGEF. The rostral ventrolateral medulla (RVLM), containing the rostral C1 (rC1) cell group, sets and maintains the tonic and reflex control of blood pressure and a plethora of inputs converge onto these neurons. We determined the relative abundance of 10 Gα subunit mRNAs, representing the four major families, within the RVLM, using quantitative RT-PCR. In situ hybridisation (ISH) combined with immunohistochemistry (IHC) was used to quantify and compare this expression in rC1 with that in the A1 and A5 cell groups. The relative abundance of Gα subunit mRNAs and a comparison of gene expression levels were quantitatively determined in normotensive and hypertensive rat strains. All 10 Gα mRNAs were detected in the RVLM of Sprague-Dawley (SD) rats with relative abundance such that Gαs>Gαi2>Gαo>Gαq>GαL>Gα11>Gαi3>Gαi1>Gα12>Gα13. The high abundance of Gα mRNAs signalling via adenylyl cyclase indicates the importance of associated GPCRs. Within the rC1 and A1 groups similar differential Gα mRNA expression profiles were seen with Gαs being found in all rC1 cells, Gα11 absent and Gαi3 rarely expressed. Thus functionally distinct subgroups exist within the rC1 and A1 cell groups as differing distributions of Gα subunits must reflect the array of GPCRs that influence their activity. In contrast, all A5 cells expressed all Gα mRNAs suggesting a functionally homogeneous group. When the 10 Gα mRNAs of the RVLM in spontaneously hypertensive rats (SHR) were compared quantitatively to Wistar-Kyoto (WKY), only Gαs and Gα12 were significantly elevated. However when the expression in normotensive SD and WKY was compared with SHR no significant differences were evident. These findings demonstrate a range of GPCR signalling capabilities in brainstem neurons important for homeostasis and suggest a prominent role for signalling via adenylyl cyclase.

A randomized controlled trial of oral melatonin supplementation and breast cancer biomarkers

We examined compliance with and the effects of melatonin supplementation on breast cancer biomarkers (estradiol, insulin-like growth factor I (IGF-1), insulin-like growth factor-binding protein 3 (IGFBP-3), and the IGF-1/IGFBP-3 ratio) in postmenopausal breast cancer survivors. In a double-blind, placebo-controlled study, postmenopausal women with a prior history of stages 0-III breast cancer who had completed active cancer treatment (including hormonal therapy) were randomly assigned to either 3 mg oral melatonin (n = 48) or placebo daily for 4 months. Plasma samples were collected at baseline and after the completion of the intervention. The primary endpoints were compliance and change in estradiol and IGF-1/IGFBP-3 levels. Ninety-five women were randomized (48 to melatonin and 47 to placebo). Eighty-six women (91%) completed the study and provided pre- and postintervention bloods. Melatonin was well tolerated without any grade 3/4 toxicity and compliance was high (89.5%). Overall, among postmenopausal women with a prior history of breast cancer, a 4-month course of 3 mg melatonin daily did not influence circulating estradiol, IGF-1, or IGFBP-3 levels. Compliance was comparable between the two groups. Short-term melatonin treatment did not influence the estradiol and IGF-1/IGBBP-3 levels. Effects of longer courses of melatonin among premenopausal women are unknown. Low baseline estradiol levels in our study population may have hindered the ability to detect any further estradiol-lowering effects of melatonin.

Isolation, identification and biological activity of gastrin-releasing peptide 1-46 (oGRP 1-46), the primary GRP gene-derived peptide product of the pregnant ovine endometrium

We have previously demonstrated that pregnant ovine endometrium expresses the gastrin-releasing peptide (GRP) gene at a high level following conceptus implantation. Here we report the isolation, characterization and biological activity of ovine GRP 1-46, the primary product of this gene in the pregnant endometrium. Full thickness 125-140-day pregnant sheep uterus (term is 145 day) was homogenized in 80% acetonitrile/2% trifluoroacetic acid (1:7 ACN/TFA), concentrated on reverse-phase C18 cartridges and chromatographed successively on gel filtration (Sephadex G-50) and reverse-phase HPLC (C18 muBondapak). Purification was monitored by RIA. Purified GRP peptide was analysed by mass spectrometry giving a major mass ion at 4963 which corresponds exactly to GRP 1-46. Other mass ions from pro-GRP did not contain a biologically active N-terminus or antigenic determinant. Proteolytic cleavage of pro-GRP to give rise to GRP(1-46) would require preferential cleavage at the Glu-Glu bond by a Glu-C2-like enzyme, rather than the trypsin-like and C-terminal amidation enzymes (PAM) that produce GRP(18-27) and GRP(1-27) in other tissues. GRP 1-46 was synthesized and receptor binding and biological activity tested on a range of rodent and human cell lines that express GRP-related receptors GRPR, NMBR and BRS3. GRP 1-46 bound GRPR and NMBR with low affinity, and mobilized inositol phosphate in cell lines expressing the GRPR and NMBR, but not BRS-3. This study describes a new processed product of the GRP gene, GRP 1-46, which is highly expressed in the pregnant sheep endometrium and which acts as a weak agonist at the GRPR and NMBR.

Cardiac norepinephrine transporter protein expression is inversely correlated to chamber norepinephrine content

The cardiac neuronal norepinephrine (NE) transporter (NET) in sympathetic neurons is responsible for uptake of released NE from the neuroeffector junction. The purpose of this study was to assess the chamber distribution of cardiac NET protein measured using [(3)H]nisoxetine binding in rat heart membranes and to correlate NE content to NET amount. In whole mounts of atria, NET was colocalized in nerve fibers with tyrosine hydroxylase (TH) immunoreactivity. NE content expressed as micrograms NE per gram tissue was lowest in the ventricles; however, NET binding was significantly higher in the left ventricle than the right ventricle and atria (P < 0.05), resulting in a significant negative correlation (r(2) = 0.922; P < 0.05) of NET to NE content. The neurotoxin 6-hydroxydopamine, an NET substrate, reduced NE content more in the ventricles than the atria, demonstrating functional significance of high ventricular NET binding. In summary, there is a ventricular predominance of NET binding that corresponds to a high NE reuptake capacity in the ventricles, yet negatively correlates to tissue NE content.

Differential Regulation of NADPH Oxidase in Sympathetic and Sensory Ganglia in Deoxycorticosterone Acetate–Salt Hypertension

We demonstrated recently that superoxide anion levels are elevated in prevertebral sympathetic ganglia of deoxycorticosterone acetate–salt hypertensive rats and that this superoxide anion is generated by reduced nicotinamide-adenine dinucleotide phosphate oxidase. In this study we compared the reduced nicotinamide-adenine dinucleotide phosphate oxidase enzyme system of dorsal root ganglion (DRG) and sympathetic celiac ganglion (CG) and its regulation in hypertension. The reduced nicotinamide-adenine dinucleotide phosphate oxidase activity of ganglion extracts was measured using fluorescence spectrometry of dihydroethidine; the activity in hypertensive dorsal root ganglion was 34% lower than in normotensive DRG. In contrast, activity was 79% higher in hypertensive CG than normotensive CG. mRNA for the oxidase subunits NOX1, NOX2, NOX4, p47 phox , and p22 phox were present in both CG and DRG; mRNA for NOX4 was significantly higher in CG than in DRG. The levels of mRNA and protein expression of the membrane-bound catalytic subunit p22 phox and of the regulatory subunits p47 phox and Rac-1 were measured in CG and DRG in normotensive and hypertensive rats. p22 phox mRNA and protein expression was greater in CG of hypertensive rats but not in DRG. Compared with normotensive controls, p47 phox mRNA and protein, as well as Rac-1 protein, were significantly decreased in hypertensive DRG but not in CG. Immunohistochemical staining of p47 phox showed translocation from cytoplasm to membrane in hypertensive CG but not in hypertensive DRG. This suggests that reduced nicotinamide-adenine dinucleotide phosphate oxidase activation in sympathetic neurons and sensory neurons is regulated in opposite directions in hypertension. This differential regulation may contribute to unbalanced vasomotor control and enhanced vasoconstriction in the splanchnic circulation.

Oestrogen receptor downregulation: an opportunity for extending the window of endocrine therapy in advanced breast cancer

BACKGROUND

Advanced breast cancer is largely incurable and current treatment modalities are aimed towards restricting tumour growth, prolonging survival, palliating symptoms and maintaining quality of life (QoL). The development of breast cancer is strongly influenced by endogenous oestrogens (and other growth factors), leading to a strong focus on the development of antioestrogenic compounds for the treatment of hormone-sensitive advanced disease.

DESIGN

This is a review of current endocrine therapies available for postmenopausal women with advanced breast cancer, examining the likely impact of newer agents on treatment strategies.

RESULTS

In postmenopausal women, current treatment options include tamoxifen, aromatase inhibitors (AIs) and megestrol acetate. Fulvestrant ('Faslodex') is a new, well-tolerated, oestrogen receptor antagonist that has no known agonist effect and is at least as effective as the AI anastrozole for the treatment of postmenopausal patients with metastatic or advanced breast cancer who have progressed on prior endocrine therapy. Fulvestrant maintains QoL throughout successful treatment.

CONCLUSIONS

Fulvestrant represents a new treatment option for postmenopausal women with advanced disease. New agents that appear to lack cross-resistance with existing treatments may be used to extend the time period during which endocrine therapy may be employed before the need for cytotoxic chemotherapy.

Double-blind, randomized trial comparing the efficacy and tolerability of fulvestrant versus anastrozole in postmenopausal women with advanced breast cancer progressing on prior endocrine therapy: results of a North American trial

PURPOSE

To compare the efficacy and tolerability of fulvestrant (formerly ICI 182,780) with anastrozole in the treatment of advanced breast cancer in patients whose disease progresses on prior endocrine treatment.

PATIENTS AND METHODS

In this double-blind, double-dummy, parallel-group study, postmenopausal patients were randomized to receive either an intramuscular injection of fulvestrant 250 mg once monthly or a daily oral dose of anastrozole 1 mg. The primary end point was time to progression (TTP). Secondary end points included objective response (OR) rate, duration of response (DOR), and tolerability.

RESULTS

Patients (n = 400) were followed for a median period of 16.8 months. Fulvestrant was as effective as anastrozole in terms of TTP (hazard ratio, 0.92; 95.14% confidence interval [CI], 0.74 to 1.14; P =.43); median TTP was 5.4 months with fulvestrant and 3.4 months with anastrozole. OR rates were 17.5% with both treatments. Clinical benefit rates (complete response + partial response + stable disease > or = 24 weeks) were 42.2% for fulvestrant and 36.1% for anastrozole (95% CI, -4.00% to 16.41%; P =.26). In responding patients, median DOR (from randomization to progression) was 19.0 months for fulvestrant and 10.8 months for anastrozole. Using all patients, DOR was significantly greater for fulvestrant compared with anastrozole; the ratio of average response durations was 1.35 (95% CI, 1.10 to 1.67; P < 0.01). Both treatments were well tolerated.

CONCLUSION

Fulvestrant was at least as effective as anastrozole, with efficacy end points slightly favoring fulvestrant. Fulvestrant represents an additional treatment option for postmenopausal women with advanced breast cancer whose disease progresses on tamoxifen therapy.

The effect of residual mass size on response to chemotherapy after surgical cytoreduction for advanced ovarian cancer: long-term results

We report an observational study of chemotherapeutic regression of ovarian tumor implants according to decrements in residual mass size after surgical cytoreduction. Cytoreductive operations were attempted on 74 consecutive patients with stages IIIB-IV disease referred for this purpose. Thirty-two patients had received one to four courses of preoperative chemotherapy (22 responses, no progressions). Postoperative chemotherapy followed current protocols at Dana Farber Cancer Institute (n=61) or referring institutions (n=13); 57 regimens contained cisplatin. Postchemotherapy response was assessed clinically or by second-look procedures. Negative findings were considered a complete remission. Masses > 1 cm were excised from 62 patients. Twelve patients were inoperable. Twenty-eight patients had complete remissions and the correlation between these and decrements in residual mass size was highly significant (P < 0.0001). Complete remissions had a uniform effect and were the only outcome predictive of survival. Preoperative treatment greatly facilitated cytoreduction but only masses 0-0.2 cm were sensitive to postoperative chemotherapy. Masses 0.5 cm or less were optimal. They made up 77% of operable patients and supplied 25 (89%) of the complete remissions. Cytoreduction is not always required but even large-volume disease in the upper abdomen can be safely excised. The concept that masses larger than 10 cm indicate general chemoresistance has not been sustained.

Nuclear factor 90 is a substrate and regulator of the eukaryotic initiation factor 2 kinase double-stranded RNA-activated protein kinase

Nuclear factor 90 (NF90) is a member of an expanding family of double-stranded (ds) RNA-binding proteins thought to be involved in gene expression. Originally identified in complex with nuclear factor 45 (NF45) as a sequence-specific DNA-binding protein, NF90 contains two double stranded RNA-binding motifs (dsRBMs) and interacts with highly structured RNAs as well as the dsRNA-activated protein kinase, PKR. In this report, we characterize the biochemical interactions between these two dsRBM containing proteins. NF90 binds to PKR through two independent mechanisms: an RNA-independent interaction occurs between the N terminus of NF90 and the C-terminal region of PKR, and an RNA-dependent interaction is mediated by the dsRBMs of the two proteins. Co-immunoprecipitation analysis demonstrates that NF90, NF45, and PKR form a complex in both nuclear and cytosolic extracts, and both proteins serve as substrates for PKR in vitro. NF90 is phosphorylated by PKR in its RNA-binding domain, and this reaction is partially blocked by the NF90 N-terminal region. The C-terminal region also inhibits PKR function, probably through competitive binding to dsRNA. A model for NF90-PKR interactions is proposed.

Clinical Activity of Trastuzumab and Vinorelbine in Women With HER2-Overexpressing Metastatic Breast Cancer

PURPOSE: To determine the response rate and toxicity profile of trastuzumab administered concurrently with weekly vinorelbine in women with HER2-overexpressing advanced breast cancer.

PATIENTS AND METHODS: Forty women with HER2-positive (+3 by immunohistochemistry, n = 30; +2 or positive, n = 10) breast cancer were enrolled onto a study of trastuzumab (4 mg/kg × 1, 2 mg/kg weekly thereafter) and vinorelbine (25 mg/m2 weekly, with dose adjusted each week for neutrophil count). Eighty-two percent of women had received prior chemotherapy as part of adjuvant (30%), metastatic (25%), or both (28%) treatment, including substantial portions of patients who had previously received either anthracyclines (20%), taxanes (15%), or both types (38%) of chemotherapy.

RESULTS: Responses were observed in 30 of 40 patients (overall response rate, 75%, conditional corrected 95% confidence interval, 57% to 89%). The response rate was 84% in patients treated with trastuzumab and vinorelbine as first-line therapy for metastatic disease, and 80% among HER2 +3 positive patients. High response rates were also seen in women treated with second- or third-line therapy, and among patients previously treated with anthracyclines and/or taxanes. Combination therapy was feasible; patients received concurrent trastuzumab and vinorelbine in 93% of treatment weeks. Neutropenia was the only grade 4 toxicity. No patients had symptomatic heart failure. Grade 2 cardiac toxicity was observed in three patients. Prior cumulative doxorubicin dose in excess of 240 mg/m2 and borderline pre-existing cardiac function were associated with grade 2 cardiac toxicity.

CONCLUSION: Trastuzumab in combination with vinorelbine is highly active in women with HER2-overexpressing advanced breast cancer and is well tolerated.

The bovine papillomavirus E2 transactivator is stimulated by the E1 initiator through the E2 activation domain

Bovine papillomavirus type 1 (BPV-1) encodes two regulatory proteins, E1 and E2, that are essential for viral replication and transcription. E1, an ATP-dependent helicase, binds to the viral ori and is essential for viral replication, while the viral transcriptional activator, E2, plays cis-dominant roles in both viral replication and transcription. At low reporter concentrations, E1 stimulates E2 enhancer function, while at high reporter concentrations, repression results. An analysis of cis requirements revealed that neither replication nor specific E1-binding sites are required for the initiators' effect on E2 transactivator function. Though no dependence on E1-binding sites was found, analysis of E1 DNA binding and ATPase mutants revealed that both domains are required for E1 modulation of E2. Through the use of E2 fusion-gene constructs we showed that a heterologous DNA-binding domain could be substituted for the E2 DNA-binding domain and this recombinant protein remained responsive to E1. Furthermore, E1 could rescue activation domain mutants of E2 defective for transactivation. These data suggest that E1 stimulation of E2 involves interactions between E1 and the E2 activation domain on DNA. We speculate that E1 may allosterically interact with the E2 activation domain, perhaps stabilizing a particular structure, which increases the enhancer function of E2.

Docetaxel administered on a weekly basis for metastatic breast cancer

PURPOSE

To evaluate the safety and efficacy of weekly docetaxel in women with metastatic breast cancer.

PATIENTS AND METHODS

Twenty-nine women were enrolled onto a study of weekly docetaxel given at 40 mg/m(2)/wk. Each cycle consisted of 6 weeks of therapy followed by a 2-week treatment break, repeated until disease progression or removal from study for toxicity or patient preference. Fifty-two percent of patients had been previously treated with adjuvant chemotherapy; 21% had received prior chemotherapy for metastatic breast cancer, and 31% had previously received anthracyclines. All patients were assessable for toxicity; two patients were not assessable for response but are included in an intent-to-treat analysis.

RESULTS

Patients received a median of 18 infusions, with a median cumulative docetaxel dose of 720 mg/m(2). There were no complete responses. Twelve patients had partial responses (overall response rate, 41%; 95% confidence interval, 24% to 61%), all occurring within the first two cycles. Similar response rates were observed among subgroups of patients previously treated either with any prior chemotherapy or with anthracyclines. An additional 17% of patients had stable disease for at least 6 months. The regimen was generally well tolerated. There was no grade 4 toxicity. Only 28% of patients had any grade 3 toxicity, most commonly neutropenia and fatigue. Acute toxicity, including myelosuppression, was mild. Fatigue, fluid retention, and eye tearing/conjunctivitis became more common with repetitive dosing, although these side effects rarely exceeded grade 2. Dose reductions were made for eight of 29 patients, most often because of fatigue (n = 5).

CONCLUSION

Weekly docetaxel is active in treating patients with metastatic breast cancer, with a side effect profile that differs from every-3-weeks therapy.

Phase I study of Doxil and vinorelbine in metastatic breast cancer

BACKGROUND

Vinorelbine and Doxil (liposomal doxorubicin) are active chemotherapeutic agents in metastatic breast cancer. A phase I study was designed to evaluate combination therapy.

PATIENTS AND METHODS

Thirty women with metastatic breast cancer were enrolled. Dose-limiting toxicity was determined through a dose escalation scheme, and defined for the first treatment cycle, only. Pharmacokinetic studies were performed during the first cycle of treatment.

RESULTS

In the first cohort of Doxil 30 mg/m2 day 1 and vinorelbine 25 mg/m2 days 1 and 8, patients experienced severe neutropenia. Vinorelbine administration was changed thereafter to days 1 and 15 of each cycle. Dose limiting toxicity was observed at Doxil 50 mg/m2 and vinorelbine 25 mg/m2. Doxil 40 mg/m2 and vinorelbine 30 mg/m2 was defined as the maximally tolerated dose. Few toxicities (principally neutro penia) were seen at this dose level, with the notable absence of significant nausea, vomiting, or alopecia. Though 63% of patients had received prior anthracycline-based chemotherapy, only one patient developed grade 2 cardiac toxicity. Pharmacokinetic studies revealed prolonged exposure to high doxorubicin concentrations for several days following Doxil administration.

CONCLUSIONS

Combination chemotherapy with Doxil and vinorelbine affords treatment with two active drugs in women with metastatic breast cancer, and appears to have a favorable toxicity profile. A schedule of Doxil 40 mg/m2 day 1 and vinorelbine 30 mg/m2 days 1 and 15 given every 28 days is recommended for phase II studies.

Sildenafil for women patients with antidepressant-induced sexual dysfunction

In an open study, sildenafil (Viagra) was prescribed for nine women outpatients who reported sexual dysfunction induced by antidepressant medication, primarily selective serotonin reuptake inhibitors. A 50 mg dose of sildenafil was prescribed, and patients were instructed to take it approximately one hour before sexual activity. They were told to increase the dose to 100 mg on the next occasion if they experienced a partial response or a lack of response to sildenafil. The nine patients, all of whom had experienced either anorgasmia or delayed orgasm with or without associated disturbances, reported significant reversal of sexual dysfunction, usually with the first dose of 50 mg of sildenafil.

Static and fatigue biomechanical properties of anterior thoracolumbar instrumentation systems. A synthetic testing model

STUDY DESIGN

A mechanical testing standard for anterior thoracolumbar instrumentation systems was introduced, using a synthetic model. Twelve recent instrumentation systems were tested in static and fatigue modes.

OBJECTIVES

To establish the testing standard for anterior thoracolumbar instrumentation systems using a synthetic model and to evaluate the static and fatigue biomechanical properties of 12 anterior thoracolumbar instrumentation systems.

SUMMARY OF BACKGROUND DATA

Although numerous studies have been performed to evaluate the biomechanics of anterior spinal instrumentation using a cadaveric or animal tissue, problems of specimen variation, lack of reproducibility, and inability to perform fatigue testing have been pointed out. In no studies has a precise synthetic testing standard for anterior thoracolumbar instrumentation systems been described.

METHODS

An ultra-high-molecular-weight polyethylene cylinder was designed according to the anatomic dimensions of the vertebral body. Two cylinders spanned by spinal instrumentation simulated a total corpectomy defect, and a compressive lateral bending load was applied. The instrumentation assembly was precisely standardized. The static destructive and fatigue tests up to 2 million cycles at three load levels were conducted, followed by the failure mode analysis. Twelve anterior instrumentation systems, consisting of five plate and seven rod systems were compared in stiffness, bending strength, and cycles to failure.

RESULTS

Static and fatigue test parameters both demonstrated highly significant differences between devices. The stiffness ranged from 280.5 kN/m in the Synthes plate (Synthes, Paoli, PA) to 67.9 kN/m in the Z-plate ATL (SofamorDanek, Memphis, TN). The Synthes plate and Kaneda SR titanium (AcroMed, Cleveland, OH) formed the highest subset in bending strength of 1516.1 N and 1209.9 N, respectively, whereas the Z-plate showed the lowest value of 407.3 N. There were no substantial differences between plate and rod devices. In fatigue, only three systems: Synthes plate, Kaneda SR titanium, and Olerud plate (Nord Opedic AB, Sweden) withstood 2 million cycles at 600 N. The failure mode analysis demonstrated plate or bolt fractures in plate systems and rod fractures in rod systems.

CONCLUSIONS

The biomechanical testing standard for anterior thoracolumbar instrumentation systems was successfully designed. It provided a repeatable and consistent experimental condition and controlling dimensional and surgical factors. The comparison of 12 instrumentation systems highlights the importance of mechanically balanced device design without a weak link in the development of instrumentation.

Osteogenic protein versus autologous interbody arthrodesis in the sheep thoracic spine. A comparative endoscopic study using the Bagby and Kuslich interbody fusion device

STUDY DESIGN

Using an in vivo interbody arthrodesis model, the efficacy of the Bagby and Kuslich (BAK) device packed with recombinant human osteogenic protein-1 (rhOP-1) was evaluated.

OBJECTIVES

To compare the efficacy of osteogenic protein with that of autograft for interbody arthrodesis, with fusion success based on biomechanical, histologic, and radiographic analyses.

SUMMARY OF BACKGROUND DATA

The use of recombinant human bone morphogenetic proteins (rhBMPs) as osteoinductive bone graft substitutes or expanders has recently gained considerable research interest, particularly when applied in posterolateral arthrodesis. However, whether these results can be extrapolated to a successful interbody spinal arthrodesis remains uncertain.

METHODS

Twelve sheep underwent a multilevel thoracic spinal decompression by thoracoscopic approach. Three noncontiguous destabilization sites (T5-T6, T7-T8, T9-T10) were prepared and randomly treated as follows. Control group treatments were nonsurgical, destabilization alone, and empty BAK. Experimental groups were treated with autograft alone, BAK device packed with autograft, or BAK device packed with rhOP-1. Four months after surgery, interbody fusion status was quantified by biomechanical testing, computed tomography, microradiography, and histomorphometry.

RESULTS

Results of biomechanical analysis showed statistically higher segmental stiffness levels when comparing the control and experimental groups with four of the five testing methods (P < 0.05). Computed tomography and microradiography characterized destabilization alone as producing one fusion in six preparations; the empty BAK, two in six;, autograft alone, four in eight; BAK with autograft, five in eight; and BAK with rhOP-1 group, six in eight-all evidenced by woven trabecular bone spanning the fusion sites. Histomorphometry yielded significantly more trabecular bone formation at the fusion sites in the three experimental groups than in the two control groups (P < 0.05).

CONCLUSIONS

Interbody spinal fusions showing biomechanical and histomorphometric equivalency to autologous fusions have been achieved with rhOP-1. The functional unit stability and histologic osteointegration evidenced by the BAK/rhOP-1 complex shows this interbody arthrodesis technique to be a viable alternative toconventional autologous iliac crest, thereby obviating the need for an iliac crest donor site and associated patient morbidity.

Sildenafil for iatrogenic serotonergic antidepressant medication-induced sexual dysfunction in 4 patients

OBJECTIVE

To evaluate the effect of sildenafil on iatrogenic serotonergic antidepressant-induced sexual dysfunction.

METHOD

Four outpatients (2 men, 2 women) who developed sexual dysfunction (erectile impotence, anorgasmia) during treatment with a serotonin reuptake inhibitor antidepressant for psychiatric disorder were selected. Each subject was initially prescribed sildenafil 50 mg to be taken approximately 1 hour before sexual activity. The dose was increased to 100 mg for a partial or failed response.

RESULTS

Four cases are detailed in case report fashion. All 4 had rapid reversal of their sexual dysfunction, usually with the first dose. Reversal equates to 1 successful use of sildenafil in each of 2 patients and 3 uses in 2 patients.

CONCLUSION

Sildenafil may be an effective treatment for serotonergic antidepressant-induced sexual dysfunction and deserves further evaluation in randomized placebo-controlled studies.

Short-chain fatty acids inhibit intestinal trefoil factor gene expression in colon cancer cells

Intestinal trefoil factor (ITF) gene expression was detected in five colon cancer cell lines. ITF was synthesized by mucous cells of LIM 1215 and LIM 1863 lines, from which it is secreted constitutively. The ITF mRNA transcript was estimated to be 0.6 kb. In LIM 1215 cells, the expression of ITF was potently and dose-dependently inhibited by short-chain fatty acids (butyrate > propionate > acetate) within 8 h of application. The inhibitory effect of butyrate was ablated by actinomycin D and preceded its effects on differentiation of LIM 1215 cells as indicated by induction of alkaline phosphatase activity and counting of periodic acid-Schiff-positive cells. The human ITF promoter contained an 11-residue consensus sequence with high homology to the butyrate response element of the cyclin D1 gene. Mobility shift assays show specific binding of this response element to nuclear protein extracts of LIM 1215 cells. We conclude that butyrate inhibits ITF expression in colon cancer cells and that this effect may be mediated transcriptionally and independently of its effects on differentiation.

The effects of rigid spinal instrumentation and solid bony fusion on spinal kinematics. A posterolateral spinal arthrodesis model

STUDY DESIGN

Spinal kinematics after the implementation of rigid spinal instrumentation or the achievement of a solid fusion was studied using a sheep posterolateral spinal arthrodesis model.

OBJECTIVE

To investigate the effects of rigid spinal instrumentation or solid fusion on spinal kinematic parameters.

SUMMARY OF BACKGROUND DATA

Numerous studies have attempted to define spinal instability in terms of kinematics. Recent in vitro studies have documented the neutral zone, or a measure of spinal laxity, as more sensitive to spinal instability than the range of motion.

METHODS

Seven skeletally mature sheep underwent a single-level posterolateral lumbar arthrodesis using autologous bone graft augmented with transpedicular screw fixation. The animals were killed 4 months after surgery. The identical surgical procedures were performed in seven sheep cadaveric spines, which served as acute postoperative controls. Each functional spinal unit was tested biomechanically before and after hardware removal. The experimental control groups consisted of destabilized spines and spines that underwent transpedicular screw fixation alone, whereas the fusion groups included spines that underwent posterolateral fusion alone or posterolateral fusion with instrumentation.

RESULTS

Rigid instrumentation and solid fusion significantly decreased the neutral zone and range of motion in all testing modes. In axial rotation and lateral bending, solid fusion reduced the range of motion significantly more than transpedicular screw fixation alone. However, in all testing modes, the neutral zones showed no statistical difference between transpedicular screw fixation alone and fusion groups.

CONCLUSIONS

The range of motion was an equivalent or better indicator of fixation or fusion stability compared with the neutral zone. Moreover, the immediate postoperative fixation stability, even if using transpedicular screw fixation, was less than the stability present after a solid fusion.

Maturation of the posterolateral spinal fusion and its effect on load-sharing of spinal instrumentation. An in vivo sheep model

We investigated the temporal relationship among the biomechanical, radiographic, and histological properties of a posterolateral spinal fusion mass to elucidate the changes in load-sharing of the spinal instrumentation and that of the fusion mass throughout the healing process. Destabilization of the posterior spinal column and transpedicular screw fixation at the segments between the third and fourth and the fifth and sixth lumbar vertebrae was performed in twenty-four sheep. A posterolateral spinal arthrodesis with use of autologous corticocancellous bone graft was done randomly at one of the two segments; the other segment (without bone graft) served as the instrumented control. Six animals each were killed at four, eight, twelve, and sixteen weeks postoperatively. Biomechanical testing showed that the posterolateral fusion mass had increased mechanical stiffness after the fourth week. The strain on the hardware, measured with use of rods instrumented with strain-gauges, decreased significantly (p < 0.01) beginning at eight weeks. Radiographically, three independent observations of each of the six animals at each time-period showed that, although all of the fusion masses were considered solid unions at sixteen weeks, bridging of trabecular bone was noted during only ten of eighteen observations at twelve weeks, three of eighteen observations at eight weeks, and none of eighteen observations at four weeks. Computerized tomography and histomorphometric analyses demonstrated that mineralization in the fusion mass increased in a linear fashion even after eight weeks. Histologically, the fusion mass consisted predominantly of woven bone at eight weeks; thereafter, it was gradually trabeculated.

CLINICAL RELEVANCE

We found a great discrepancy between biomechanical stability and histological maturation of the posterolateral fusion mass. The biomechanical properties of a stable spinal fusion preceded the radiographic appearance of a solid fusion by at least eight weeks, suggesting that immature woven bone provided substantial stiffness to the fusion mass. The spinal instrumentation was subjected predominantly to bending stress rather than to axial stress, and the load-sharing of the spinal instrumentation decreased concurrently with the development of the spinal fusion.

The outcome of posterolateral fusion in highly selected patients with discogenic low back pain

STUDY DESIGN

A prospective analysis of the clinical outcome of a consecutive series of patients treated with posterior lumbar arthrodesis. Preoperative data were collected retrospectively by chart review.

OBJECTIVES

To measure by independent review the clinical outcome of posterolateral intertransverse fusion as a treatment for discogenic low back pain in a highly selected group of patients.

SUMMARY OF BACKGROUND DATA

Although numerous studies have reported on the surgical management of degenerative disc disease, they have been difficult to interpret because they lack patient-oriented outcome assessment and objective pain measurement criteria, independent review, and include patients with diagnoses other than degenerative disc disease.

METHODS

Between 1991 and February 1993 all patients seen by a single surgeon, evaluated with magnetic resonance imaging and discography, and treated with posterolateral lumbar fusion were reviewed by independent investigation. Outcome was assessed in the areas of radiographic fusion, pain, function, and patient satisfaction.

RESULTS

Twenty-three patients (12 women, 11 men; 100% follow-up an average of 47 months after surgery [range, 24-84 months]) met the inclusion criteria. Overall, 39% had a good or excellent result, 13% fair, and 48% poor. Nine of 10 patients receiving worker's compensation had a poor result, four of five patients with radiographic pseudarthrosis had a poor result. Statistically significant improvement in the visual analogue scale was noted in the good and excellent group (P = 0.0001) and the fair group (P = 0.002) with no change in the poor group. Patients out of work more than 3 months before surgery tended to have poor results. Overall, 56% of patients were extremely satisfied with the result of their surgery.

CONCLUSION

Posterolateral intertransverse fusion can be used to successfully manage chronic discogenic back pain. However, patient selection remains a challenge, and successful outcome appears to be limited in the subset of patients receiving worker's compensation and those chronically disabled. Prospective and randomized study with objective pain criteria, independent review, and patient-oriented outcome is recommended.

Minimally invasive surgical techniques to treat spine infections

Minimally invasive techniques including closed laparoscopy and thoracoscopy as well as video-assisted procedures using limited open incisions provide an excellent alternative for treating vertebral osteomyelitis and tuberculous infections in the thoracic and lumbar spine. The traditional principles of surgical debridement and a stable interbody fusion are unchanged when applying endoscopic techniques. In the future, the spinal endoscopist will have available a larger selection of endoscopic instruments, more sophisticated video technology, and the development of anterior instrumentation systems to allow for rigid internal fixation. These advances, along with the surgeon's endoscopic experience and refined techniques, will further establish minimally invasive surgical techniques in the field of spinal surgery.

Endocrine and cytotoxic therapies for the management of advanced local breast cancer. Current clinical investigation

There is a need for more clinical investigation in advanced local breast cancer. Both chemotherapy and endocrine therapy improve disease-free and overall survival and are now a routine part of standard patient care. Dose-intensive chemotherapy should be reserved for younger patients in large, controlled clinical trials. For operable patients, adequate surgical therapy of the breast and axilla remains a standard of care and provides the most important piece of prognostic information (i.e., the number of involved axillary lymph nodes). Tamoxifen treatment of the estrogen receptor-positive postmenopausal patient remains the standard, although chemotherapy may add a further increment to disease-free survival.

The distal biceps tendon. Two potential mechanisms involved in its rupture: arterial supply and mechanical impingement

The purpose of this anatomic study was to evaluate potential causes of rupture of the distal biceps tendon, to assess the dynamic relationship of the proximal radioulnar joint during pronation and supination, and to identify potential sites of impingement of the distal biceps tendon. For the anatomic study specimens were evaluated by light microscopy, multiplanar gross dissections, and Spalteholz vascular injection. For the radiographic study computed tomography was used to assess dynamic changes in the radioulnar space in pronation, neutral position, and supination. Three vascular zones were identified in the distal biceps tendon. Vascular contributions were consistently noted from the brachial artery proximally and from the posterior recurrent artery distally. A hypovascular zone averaging 2.14 cm was evident between the proximal and distal zones. On sectioning through the proximal radioulnar joint 85% of the space was occupied by the distal tendon in full pronation. In addition, computed tomography imaging revealed a 50% reduction in the radioulnar joint at the radial tuberosity from full supination to full pronation. Mechanical impingement on the biceps tendon during forearm rotation and hypovascularity within sections of the tendon may contribute to attritional ruptures of the distal biceps tendon.