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1.  Regioselective Nitration of Nα,N1-Bis(trifluoroacetyl)-L-Tryptophan Methyl Ester: Efficient Synthesis of 2-Nitro and 6-Nitro-N-Trifluoroacetyl-L-Tryptophan Methyl Ester 
Nitration of Nα,N1-bis(trifluoroacetyl)-L-tryptophan methyl ester with HNO3 in acetic anhydride at 0° C provides Nα-trifluoroacetyl-2-nitro-L-tryptophan methyl ester in 67% yield, whereas nitration in trifluoroacetic acid at 0° C gives Nα-trifluoroacetyl-6-nitro-L-tryptophan methyl ester in 69% yield.
PMCID: PMC4335804  PMID: 18851915
2.  Sympathetic axonopathies and hyperinnervation in the small intestine smooth muscle of aged Fischer 344 rats 
Autonomic neuroscience : basic & clinical  2013;179(0):10.1016/j.autneu.2013.09.002.
It is well documented that the intrinsic enteric nervous system of the gastrointestinal (GI) tract sustains neuronal losses and reorganizes as it ages. In contrast, age-related remodeling of the extrinsic sympathetic projections to the wall of the gut is poorly characterized. The present experiment, therefore, surveyed the sympathetic projections to the aged small intestine for axonopathies. Furthermore, the experiment evaluated the specific prediction that catecholaminergic inputs undergo hyperplastic changes. Jejunal tissue was collected from 3-, 8-, 16-, and 24-month-old male Fischer 344 rats, prepared as whole mounts consisting of the muscularis, and processed immunohistochemically for tyrosine hydroxylase, the enzymatic marker for norepinephrine, and either the protein CD163 or the protein MHCII, both phenotypical markers for macrophages. Four distinctive sympathetic axonopathy profiles occurred in the small intestine of the aged rat: (1) swollen and dystrophic terminals, (2) tangled axons, (3) discrete hyperinnervated loci in the smooth muscle wall, including at the bases of Peyer's patches, and (4) ectopic hyperplastic or hyperinnervating axons in the serosa/subserosal layers. In many cases, the axonopathies occurred at localized and limited foci, involving only a few axon terminals, in a pattern consistent with incidences of focal ischemic, vascular, or traumatic insult. The present observations underscore the complexity of the processes of aging on the neural circuitry of the gut, with age-related GI functional impairments likely reflecting a constellation of adjustments that range from selective neuronal losses, through accumulation of cellular debris, to hyperplasias and hyperinnervation of sympathetic inputs.
PMCID: PMC3844004  PMID: 24104187
CD163; Gastrointestinal; MHCII; Muscularis; Myenteric; Resident Macrophages
3.  Architecture of Vagal Motor Units Controlling Striated Muscle of Esophagus: Peripheral Elements Patterning Peristalsis? 
Autonomic neuroscience : basic & clinical  2013;179(0):10.1016/j.autneu.2013.08.069.
Little is known about the architecture of the vagal motor units that control esophageal striated muscle, in spite of the fact that these units are necessary, and responsible, for peristalsis. The present experiment was designed to characterize the motor neuron projection fields and terminal arbors forming esophageal motor units. Nucleus ambiguus compact formation neurons of the rat were labeled by bilateral intracranial injections of the anterograde tracer dextran biotin. After tracer transport, thoracic and abdominal esophagi were removed and prepared as whole mounts of muscle wall without mucosa or submucosa. Labeled terminal arbors of individual vagal motor neurons (n = 78) in the esophageal wall were inventoried, digitized and analyzed morphometrically. The size of individual vagal motor units innervating striated muscle, throughout thoracic and abdominal esophagus, averaged 52 endplates per motor neuron, a value indicative of fine motor control. A majority (77%) of the motor terminal arbors also issued one or more collateral branches that contacted neurons, including nitric oxide synthase-positive neurons, of local myenteric ganglia. Individual motor neuron terminal arbors co-innervated, or supplied endplates in tandem to, both longitudinal and circular muscle fibers in roughly similar proportions (i.e., two endplates to longitudinal for every three endplates to circular fibers). Both the observation that vagal motor unit collaterals project to myenteric ganglia and the fact that individual motor units co-innervate longitudinal and circular muscle layers are consistent with the hypothesis that elements contributing to peristaltic programming inhere, or are “hardwired,” in the peripheral architecture of esophageal motor units.
PMCID: PMC3844123  PMID: 24044976
deglutition; enteric; motor neuron; myenteric plexus; NOS neurons; peristalsis; swallowing
5.  Protocol for a systematic review of reductions in therapy for children with low-risk febrile neutropenia 
Systematic Reviews  2014;3:119.
Febrile neutropenia is a common complication of therapy in children with cancer. Some patients are at low risk of complications, and research has considered reduction in therapy for these patients. A previous systematic review broadly considered whether outpatient treatment and oral antibiotics were safe in this context and concluded that this was likely to be the case. Since that review, there has been further research in this area. Therefore, we aim to provide a more robust answer to these questions and to additionally explore whether the exact timing of discharge, including entirely outpatient treatment, has an impact on outcomes.
The search will cover MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, CDSR, CENTRAL, LILACS, HTA and DARE. A full search strategy is provided. Key conference proceedings and reference lists of included papers will be hand searched. Prominent authors/clinicians in the field will be contacted. We will include randomised and quasi-randomised controlled trials along with prospective single-arm studies that examine the location of therapy and/or the route of administration of antibiotics in children or young adults (aged less than 18 years) who attend paediatric services with fever and neutropenia due to treatment for cancer and are assessed to be at low risk of medical complications. Studies will be screened and data extracted by one researcher and independently checked by a second. All studies will be critically appraised using tools appropriate to the study design. Data from randomised controlled trials (RCTs) will be combined to provide comparative estimates of treatment failure, safety and adequacy. Information from quasi-randomised trials and single-arm studies will provide further data on the safety and adequacy of regimes. Random effects meta-analysis will be used to combine studies. A detailed analysis plan, including assessment of heterogeneity and publication bias, is provided.
This study will aim to specifically define the features of a low-risk strategy that will maintain levels of safety and adequacy equivalent to those of traditional treatments. This will both inform the development of services and provide patients and families with data to help them make an informed decision about care.
Systematic review registration
PROSPERO CRD42014005817
PMCID: PMC4234526  PMID: 25336249
Fever; Neutropenia; Cancer; Children; Outpatient
6.  Vagal Afferent Innervation of the Lower Esophageal Sphincter 
To supply a fuller morphological characterization of the vagal afferents innervating the lower esophageal sphincter (LES), specifically to label vagal terminals in the tissues forming the LES in the gastroesophageal junction, the present experiment employed injections of dextran biotin into the nodose ganglia of rats. Four types of vagal afferents innervated the LES. Clasp and sling muscle fibers were directly and prominently innervated by intramuscular arrays (IMAs). Individual IMA terminals subtended about 16° of arc of the esophageal circumference, and, collectively, the terminal fields were distributed within the muscle ring to establish a 360° annulus of mechanoreceptors in the sphincter wall. 3D morphometry of the terminals established that, compared to sling muscle IMAs, clasp muscle IMAs had more extensive arbors and larger receptive fields. In addition, at the cardia, local myenteric ganglia between smooth muscle sheets and striated muscle bundles were innervated by intraganglionic laminar endings (IGLEs), in a pattern similar to the innervation of the myenteric plexus throughout the stomach and esophagus. Finally, as previously described, the principle bundle of sling muscle fibers that links LES sphincter tissue to the antropyloric region of the lesser curvature was innervated by exceptionally long IMAs as well as by unique web ending specializations at the distal attachment of the bundle. Overall, the specialized varieties of densely distributed vagal afferents innervating the LES underscore the conclusion that these sensory projections are critically involved in generating LES reflexes and may be promising targets for managing esophageal dysfunctions.
PMCID: PMC3749274  PMID: 23583280
antrum; cardia; GERD; lesser curvature; mechanoreceptor; nodose ganglion; pylorus; visceral afferent
7.  Effects of hydrostatic pressure on the conformational equilibrium of tryptophan synthase from Salmonella typhimurium 
A wide range of parameters influence allosteric communications between the α- and β-subunits of the Trp synthase α2β2 multienzyme complex with L-Ser, including monovalent cations, pH, temperature, ligands, organic solvents, and hydrostatic pressure. The conformational change from closed to open can be monitored either by absorbance at 423 nm or fluorescence at 495 nm from the pyridoxal-5′-phosphate-L-Ser complex. Pressure perturbation was used to quantify the effects of monovalent cations, ligands, and mutations on the conformational equilibrium of Trp synthase. P-jump kinetics in the presence of Na+, NH4+, and Na+ together with benzimidazole were also examined. The plots of lnk versus P are nonlinear and require a compressibility (β‡o) term to obtain a good fit. β‡o is positive for the Na+ enzyme but negative for NH4+ and Na+ with benzimidazole. These results suggest that there is a large contribution of solvation to the kinetics of the conformational change of Trp synthase. The relaxation kinetics are also different if the P-jumps are made by increasing or decreasing pressure, suggesting that the enzyme conformations are ensembles of microstates.
PMCID: PMC4156104  PMID: 20233374
tryptophan synthase; allostery; pyridoxal-5′-phosphate; compressibility; solvation
8.  Towards Graduate Medical Education (GME) Accountability: Measuring the Outcomes of GME Institutions 
Graduate medical education (GME) plays a key role in the U.S. health care workforce, defining its overall size and specialty distribution, and influencing physician practice locations. Medicare provides nearly $10 billion annually to support GME, and faces growing policymaker interest in creating accountability measures. The purpose of this study was to develop and test candidate GME outcome measures related to physician workforce.
The authors performed a secondary analysis of data from the American Medical Association Physician Masterfile, National Provider Identifier file, Medicare claims, and National Health Service Corps, measuring the number and percentage of graduates from 2006 to 2008 practicing in high-need specialties and underserved areas aggregated by their U.S. GME program.
Average overall primary care production rate was 25.2% for the study period, although this is an overestimate since hospitalists could not be excluded. Of 759 sponsoring institutions, 158 produced no primary care graduates, and 184 produced more than 80%. An average of 37.9% of Internal Medicine residents were retained in primary care, including hospitalists. Mean general surgery retention was 38.4%. Overall, 4.8% of graduates practiced in rural areas; 198 institutions produced no rural physicians, and 283 institutions produced no Federally Qualified Health Center or Rural Health Clinic physicians.
GME outcomes are measurable for most institutions and training sites. Specialty and geographic locations vary significantly. These findings can inform educators and policy-makers during a period of increased calls to align the GME system with national health needs.
PMCID: PMC3761381  PMID: 23752037
9.  Toward Defining and Measuring Social Accountability in Graduate Medical Education: A Stakeholder Study 
Since 1965, Medicare has publically financed graduate medical education (GME) in the United States. Given public financing, various advisory groups have argued that GME should be more socially accountable. Several efforts are underway to develop accountability measures for GME that could be tied to Medicare payments, but it is not clear how to measure or even define social accountability.
We explored how GME stakeholders perceive, define, and measure social accountability.
Through purposive and snowball sampling, we completed semistructured interviews with 18 GME stakeholders from GME training sites, government agencies, and health care organizations. We analyzed interview field notes and audiorecordings using a flexible, iterative, qualitative group process to identify themes.
Three themes emerged in regards to defining social accountability: (1) creating a diverse physician workforce to address regional needs and primary care and specialty shortages; (2) ensuring quality in training and care to best serve patients; and (3) providing service to surrounding communities and the general public. All but 1 stakeholder believed GME institutions have a responsibility to be socially accountable. Reported barriers to achieving social accountability included training time constraints, financial limitations, and institutional resistance. Suggestions for measuring social accountability included reviewing graduates' specialties and practice locations, evaluating curricular content, and reviewing program services to surrounding communities.
Most stakeholders endorsed the concept of social accountability in GME, suggesting definitions and possible measures that could inform policy makers calls for increased accountability despite recognized barriers.
PMCID: PMC3771174  PMID: 24404308
10.  Alpha-synuclein expression patterns in the colonic submucosal plexus of the aging Fischer 344 rat: Implications for biopsies in aging and neurodegenerative disorders? 
This experiment assessed normative expression patterns of alpha-synuclein (SYNC), including ganglionic remodeling and development of SYNC pathologies, in the submucosal plexus (SMP) of the colon during healthy aging. The observations address age-associated changes in bowel function and are relevant to evaluations of SMP-containing colonic biopsies for SYNC or synucleinopathies associated with aging and peripheral neurodegenerative diseases.
Colonic submucosal whole mounts from groups of virgin male Fischer 344 rats (n ≥ 8 per group) at 4, 8, 16 and 24 months of age were processed immunohistochemically for SYNC and the pan-neuronal marker HuC/D. Additionally, macrophages immunoreactive for MHCII were examined. Stereological protocols were used to generate unbiased estimates of neuron density, neurons per ganglion, neurons per ganglionic area, and neuron size.
Key Results
The protein SYNC was expressed in a subpopulation of SMP neurons, in both nucleus and cytoplasm. The general age-associated pattern across different cell counts was an increase in the number of SYNC+ neurons between 4 and 8 months of age, with progressively decreasing numbers of both SYNC+ and SYNC− neurons over the remaining lifespan. The soma size of SYNC+ neurons increased progressively with age. Aggregated SYNC occurred in the aging SMP, and macrophages with alternatively activated profiles were located adjacent to pathological SYNC deposits, consistent with ongoing phagocytosis.
Conclusions & Inferences
Changes in SYNC expression with age, including a baseline of accumulating synucleopathies in the healthy aging SMP, need to be considered when interpreting either functional disturbances or biopsies of the aging colon.
PMCID: PMC3735646  PMID: 23809578
Colon; Enteric; MHCII; Calbindin; Parkinson's disease
11.  Prostaglandin pathway gene expression in human placenta, amnion and choriodecidua is differentially affected by preterm and term labour and by uterine inflammation 
Elucidation of the biochemical pathways involved in activation of preterm and term human labour would facilitate the development of effective management and inform judgements regarding the necessity for preterm tocolysis and post-term induction. Prostaglandins act at all stages of human reproduction, and are potentially activators of labour.
Expression of 15 genes involved in prostaglandin synthesis, transport and degradation was measured by qPCR using tissue samples from human placenta, amnion and choriodecidua at preterm and full-term vaginal and caesarean delivery. Cellular localisation of eight prostaglandin pathway proteins was determined by immunohistochemistry.
Expression of prostaglandin pathway genes was differentially affected by factors including gestational age at delivery, and the incidence and duration of labour. Chorioamnionitis/deciduitis was associated with upregulation of PTGS2 (prostaglandin-endoperoxide synthase 2 (prostaglandin G/H synthase and cyclooxygenase)), along with the inflammatory genes IL8 (interleukin 8), S100A8 (S100 calcium binding protein A8) and TLR2 (toll-like receptor 2), in amnion and choriodecidua, and with downregulation of CBR1 (carbonyl reductase 1) and HPGD (hydroxyprostaglandin dehydrogenase 15-(NAD)) in choriodecidua. Protein localisation differed greatly between the various maternal and fetal cell types.
Preterm and term labour are associated with distinct prostaglandin pathway expression profiles; inflammation provokes specific changes, unrelated to the presence of labour; spontaneous and induced term labour are indistinguishable.
PMCID: PMC4223419  PMID: 25048443
Parturition; Inflammation; Pregnancy; Uterus
Anatomical record (Hoboken, N.J. : 2007)  2013;296(4):10.1002/ar.22675.
With age, alpha-synuclein (α-SYNC) misfolds and forms insoluble deposits of protein in the myenteric plexus, leading presumably to dystrophy and degeneration in the circuitry controlling gastrointestinal (GI) function. The present experiment examined aggregates of α-SYNC in the aging small intestine and investigated how macrophages in the wall of the GI tract respond to these aberrant deposits. Groups of adult and aged Fisher 344 rats were studied. Whole mounts of duodenal, jejunal and ileal smooth muscle wall, including the myenteric plexus, were prepared. Double labeling immunohistochemistry was used to stain α-SYNC protein and the phenotypic macrophage antigens CD163 and MHCII. Alpha-synuclein accumulated in dense aggregates in axons of both postganglionic and preganglionic neurons throughout the small intestine. Staining patterns suggested that deposits of protein occur initially in axonal terminals and then spread retrogradely towards the somata. Macrophages that were adjacent to dystrophic terminal processes were swollen and contained vacuoles filled with insoluble α-SYNC, and these macrophages commonly had the phenotype of alternatively activated phagocytes. The present results suggest that macrophages play an active phagocytotic role in removing α-SYNC aggregates that accumulate with age in the neural circuitry of the gut. Our observations further indicate that this housekeeping response does not clear the protein sufficiently to eliminate all synucleinopathies or their precursor aggregates from the healthy aging GI tract. Thus, accumulating deposits of insoluble α-SYNC in the wall of the GI tract may contribute, especially when compounded by disease or inflammation, to the age-associated neuropathies in the gut that compromise GI function.
PMCID: PMC3851024  PMID: 23441091
Aging; Enteric; Myenteric; Resident Macrophage
13.  Increasing value and reducing waste in biomedical research regulation and management 
Lancet  2014;383(9912):176-185.
After identification of an important research question and selection of an appropriate study design, waste can arise from the regulation, governance, and management of biomedical research. Obtaining regulatory and governance approval has become increasingly burdensome and disproportionate to the conceivable risks to research participants. Regulation and governance involve interventions that are assumed to be justified in the interests of patients and the public, but they can actually compromise these interests. Inefficient management of the procedural conduct of research is wasteful, especially if it results in poor recruitment and retention of participants in well designed studies addressing important questions. These sources of waste can be minimised if the following four recommendations are addressed. First, regulators should use their influence to reduce other causes of waste and inefficiency in research. Second, regulators and policy makers should work with researchers, patients, and health professionals to streamline and harmonise the laws, regulations, guidelines, and processes that govern whether and how research can be done, and ensure that they are proportionate to the plausible risks associated with the research. Third, researchers and research managers should increase the efficiency of recruitment, retention, data monitoring, and data sharing in research through use of research designs known to reduce inefficiencies, and further research should be done to learn how efficiency can be increased. Finally, everyone, particularly those responsible for health-care systems, should promote integration of research into everyday clinical practice. Regulators and researchers should monitor adherence to each of these recommendations and publish metrics.
PMCID: PMC3952153  PMID: 24411646
14.  Salmonella Utilizes d-Glucosaminate via a Mannose Family Phosphotransferase System Permease and Associated Enzymes 
Journal of Bacteriology  2013;195(18):4057-4066.
Salmonella enterica is a globally significant bacterial food-borne pathogen that utilizes a variety of carbon sources. We report here that Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) uses d-glucosaminate (2-amino-2-deoxy-d-gluconic acid) as a carbon and nitrogen source via a previously uncharacterized mannose family phosphotransferase system (PTS) permease, and we designate the genes encoding the permease dgaABCD (d-glucosaminate PTS permease components EIIA, EIIB, EIIC, and EIID). Two other genes in the dga operon (dgaE and dgaF) were required for wild-type growth of S. Typhimurium with d-glucosaminate. Transcription of dgaABCDEF was dependent on RpoN (σ54) and an RpoN-dependent activator gene we designate dgaR. Introduction of a plasmid bearing dgaABCDEF under the control of the lac promoter into Escherichia coli strains DH5α, BL21, and JM101 allowed these strains to grow on minimal medium containing d-glucosaminate as the sole carbon and nitrogen source. Biochemical and genetic data support a catabolic pathway in which d-glucosaminate, as it is transported across the cell membrane, is phosphorylated at the C-6 position by DgaABCD. DgaE converts the resulting d-glucosaminate-6-phosphate to 2-keto-3-deoxygluconate 6-phosphate (KDGP), which is subsequently cleaved by the aldolase DgaF to form glyceraldehyde-3-phosphate and pyruvate. DgaF catalyzes the same reaction as that catalyzed by Eda, a KDGP aldolase in the Entner-Doudoroff pathway, and the two enzymes can substitute for each other in their respective pathways. Examination of the Integrated Microbial Genomes database revealed that orthologs of the dga genes are largely restricted to certain enteric bacteria and a few species in the phylum Firmicutes.
PMCID: PMC3754740  PMID: 23836865
Hypertension  2012;61(1):82-88.
The objective of our study was to determine the effects of two antihypertensive drug dose schedules (‘PM dose’ and ‘Add on dose’) on nocturnal blood pressure (BP) in comparison to usual therapy (‘AM dose’) in African Americans with hypertensive chronic kidney disease (CKD) and controlled office BP. In a three period, cross-over trial, former participants of the African American Study of Kidney Disease were assigned to receive the following three regimens, each lasting 6 weeks, presented in random order: AM dose (once daily antihypertensive medications taken in the morning), PM dose (once daily antihypertensives taken at bedtime) and ‘Add on dose’ (once daily antihypertensives taken in the morning and an additional antihypertensive medication before bedtime [diltiazem 60–120 mg, hydralazine 25 mg, or additional ramipril 5 mg]). Ambulatory BP monitoring was performed at the end of each period. The primary outcome was nocturnal systolic BP. Mean age of the study population (n=147) was 65.4 years, 64% were male, mean estimated GFR was 44.9 ml/min/1.73 m2. At the end of each period, mean (SE) nocturnal systolic BP was 125.6 (1.2) mm Hg in the AM dose, 123.9 (1.2) mm Hg in the PM dose, and 123.5(1.2) mm Hg in the Add-on dose. None of the pairwise differences in nocturnal, 24-hour and daytime systolic BP were statistically significant. Among African Americans with hypertensive CKD, neither PM (bedtime) dosing of once daily antihypertensive nor the addition of drugs taken at bedtime significantly reduced nocturnal BP compared to morning dosing of anti-hypertensive medications.
PMCID: PMC3523681  PMID: 23172931
Nocturnal blood pressure; chronic kidney disease; hypertension
16.  Risk of Hyperkalemia in Nondiabetic Patients With Chronic Kidney Disease Receiving Antihypertensive Therapy 
Transplantation  2011;92(7):10.1097/TP.0b013e31822dc36b.
The incidence and factors associated with hyperkalemia in patients with chronic kidney disease (CKD) treated with angiotensin converting enzyme inhibitors (ACEIs) and other antihypertensive drugs was investigated using the African American Study of Kidney Disease and Hypertension (AASK) database.
A total of 1094 nondiabetic adults with hypertensive CKD (glomerular filtration rate [GFR], 20–65 mL/min/1.73 m2) were followed for 3.0 to 6.4 years in the AASK trial. Participants were randomly assigned to ACEI, β-blocker (BB), or dihydropyridine calcium channel blocker (CCB). The outcome variables for this analysis were a serum potassium level higher than 5.5 mEq/L (to convert to millimoles per liter, multiply by 1.0), or a clinical center initiated hyperkalemia stop point.
A total of 6497 potassium measurements were obtained, and 80 events in 51 subjects were identified (76 events driven by a central laboratory result and 4 driven by a clinical center–initiated hyperkalemia stop point). Compared with a GFR higher than 50 mL/min/1.73 m2, after multivariable adjustment, the hazard ratio (HR) for hyperkalemia in patients with a GFR between 31 and 40 mL/min/1.73 m2 and a GFR lower than 30 mL/min/1.73 m2 was 3.61 (95% confidence interval [CI], 1.42–9.18 [P=.007]) and 6.81 (95% CI, 2.67–17.35 [P<.001]), respectively; there was no increased risk of hyperkalemia if GFR was 41 to 50 mL/min/1.73 m2. Use of ACEIs was associated with more episodes of hyperkalemia compared with CCB use (HR, 7.00; 95% CI, 2.29–21.39 [P<.001]) and BB group (HR, 2.85; 95% CI, 1.50–5.42 [P=.001]). Diuretic use was associated with a 59% decreased risk of hyperkalemia.
In nondiabetic patients with hypertensive CKD treated with ACEIs, the risk of hyperkalemia is small, particularly if baseline and follow-up GFR is higher than 40 mL/min/1.73 m2. Including a diuretic in the regimen may markedly reduce risk of hyperkalemia.
PMCID: PMC3831506  PMID: 21832957
17.  Vagal Sensory Innervation of the Gastric Sling Muscle and Antral Wall: Implications for GERD? 
The gastric sling muscle has not been investigated for possible sensory innervation, in spite of the key roles the structure plays in lower esophageal sphincter (LES) function and gastric physiology. Thus, the present experiment used tracing techniques to label vagal afferents and survey their projections in the lesser curvature.
Sprague Dawley rats received injections of dextran biotin into the nodose ganglia. Fourteen days post-injection, animals were euthanized and their stomachs were processed to visualize the vagal afferent innervation. In different cases, neurons, muscle cells, or interstitial cells of Cajal were counterstained.
Key Results
The sling muscle is innervated throughout its length by vagal afferent intramuscular arrays (IMAs) associated with interstitial cells of Cajal. In addition, the distal antral attachment site of the sling muscle is innervated by a novel vagal afferent terminal specialization, an antral web ending. The muscle wall of the distal antrum is also innervated by conventional IMAs and intraganglionic laminar endings (IGLEs), the two types of mechanoreceptors found throughout stomach smooth muscle.
Conclusions & Inferences
The innervation of sling muscle by IMAs, putative stretch receptors, suggests that sling sensory feedback may generate vago-vagal or other reflexes with vagal afferent limbs. The restricted distribution of afferent web endings near the antral attachments of sling fibers suggests the possibility of specialized mechanoreceptor functions linking antral and pyloric activity to the operation of the LES. Dysfunctional sling afferents could generate LES motor disturbances, or normative compensatory sensory feedback from the muscle could compromise therapies targeting only effectors.
PMCID: PMC3776304  PMID: 22925069
interstitial cells of Cajal; lower esophageal sphincter; mechanoreceptor; reflux; vagus
18.  Macrophages Associated with the Intrinsic and Extrinsic Autonomic Innervation of the Rat Gastrointestinal Tract 
Autonomic Neuroscience  2012;169(1):12-27.
Interactions between macrophages and the autonomic innervation of gastrointestinal (GI) tract smooth muscle have received little experimental attention. To better understand this relationship, immunohistochemistry was performed on GI whole mounts from rats at three ages. The phenotypes, morphologies, and distributions of gut macrophages are consistent with the cells performing extensive housekeeping functions in the smooth muscle layers. Specifically, a dense population of macrophages was located throughout the muscle wall where they were distributed among the muscle fibers and along the vasculature. Macrophages were also associated with ganglia and connectives of the myenteric plexus and with the sympathetic innervation. Additionally, these cells were in tight registration with the dendrites and axons of the myenteric neurons as well as the varicosities along the length of the sympathetic axons, suggestive of a contribution by the macrophages to the homeostasis of both synapses and contacts between the various elements of the enteric circuitry. Similarly, macrophages were involved in the presumed elimination of neuropathies as indicated by their association with dystrophic neurons and neurites which are located throughout the myenteric plexus and smooth muscle wall of aged rats. Importantly, the patterns of macrophage-neuron interactions in the gut paralleled the much more extensively characterized interactions of macrophages (i.e., microglia) and neurons in the CNS. The present observations in the PNS as well as extrapolations from homologous microglia in the CNS suggest that GI macrophages play significant roles in maintaining the nervous system of the gut in the face of wear and tear, disease, and aging.
PMCID: PMC3361649  PMID: 22436622
aged; alpha-synuclein; CD163; myenteric; MHCII; muscularis; resident macrophage; sympathetic
19.  A needs-based method for estimating the behavioral health staff needs of community health centers 
Federally Qualified Health Centers are expanding to increase access for millions of more Americans with a goal of doubling capacity to serve 40 million people. Health centers provide a lot of behavioral health services but many have difficulty accessing mental health and substance use professionals for their patients. To meet the needs of the underserved and newly insured it is important to better estimate how many behavioral health professionals are needed.
Using health center staffing data and behavioral health service patterns from the 2010 Uniform Data System and the 2010 National Survey on Drug Use and Health, we estimated the number of patients likely to need behavioral health care by insurance type, the number of visits likely needed by health center patients annually, and the number of full time equivalent providers needed to serve them.
More than 2.5 million patients, 12 or older, with mild or moderate mental illness, and more than 357,000 with substance abuse disorders, may have gone without needed behavioral health services in 2010. This level of need would have required more than 11,600 full time providers. This translates to approximately 0.9 licensed mental health provider FTE, 0.1 FTE psychiatrist, 0.4 FTE other mental health staff, and 0.3 FTE substance abuse provider per 2,500 patients. These estimates suggest that 90% of current centers could not access mental health services or provide substance abuse services to fully meet patients’ needs in 2010. If needs are similar after health center expansion, more than 27,000 full time behavioral health providers will be needed to serve 40 million medical patients, and grantees will need to increase behavioral health staff more than four-fold.
More behavioral health is seen in primary care than in any other setting, and health center clients have greater behavioral health needs than typical primary care patients. Most health centers needed additional behavioral health services in 2010, and this need will be magnified to serve 40 million patients. Further testing of these workforce models are needed, but the degree of current underservice suggests that we cannot wait to move on closing the gap.
PMCID: PMC3750356  PMID: 23816353
20.  Intensive Blood-Pressure Control in Hypertensive Chronic Kidney Disease 
The New England journal of medicine  2010;363(10):918-929.
In observational studies, the relationship between blood pressure and end-stage renal disease (ESRD) is direct and progressive. The burden of hypertension-related chronic kidney disease and ESRD is especially high among black patients. Yet few trials have tested whether intensive blood-pressure control retards the progression of chronic kidney disease among black patients.
We randomly assigned 1094 black patients with hypertensive chronic kidney disease to receive either intensive or standard blood-pressure control. After completing the trial phase, patients were invited to enroll in a cohort phase in which the blood-pressure target was less than 130/80 mm Hg. The primary clinical outcome in the cohort phase was the progression of chronic kidney disease, which was defined as a doubling of the serum creatinine level, a diagnosis of ESRD, or death. Follow-up ranged from 8.8 to 12.2 years.
During the trial phase, the mean blood pressure was 130/78 mm Hg in the intensive-control group and 141/86 mm Hg in the standard-control group. During the cohort phase, corresponding mean blood pressures were 131/78 mm Hg and 134/78 mm Hg. In both phases, there was no significant between-group difference in the risk of the primary outcome (hazard ratio in the intensive-control group, 0.91; P = 0.27). However, the effects differed according to the baseline level of proteinuria (P = 0.02 for interaction), with a potential benefit in patients with a protein-to-creatinine ratio of more than 0.22 (hazard ratio, 0.73; P = 0.01).
In overall analyses, intensive blood-pressure control had no effect on kidney disease progression. However, there may be differential effects of intensive blood-pressure control in patients with and those without baseline proteinuria. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases, the National Center on Minority Health and Health Disparities, and others.)
PMCID: PMC3662974  PMID: 20818902
21.  Enzyme-Synthesized Highly Branched Maltodextrins Have Slow Glucose Generation at the Mucosal α-Glucosidase Level and Are Slowly Digestible In Vivo 
PLoS ONE  2013;8(4):e59745.
For digestion of starch in humans, α-amylase first hydrolyzes starch molecules to produce α-limit dextrins, followed by complete hydrolysis to glucose by the mucosal α-glucosidases in the small intestine. It is known that α-1,6 linkages in starch are hydrolyzed at a lower rate than are α-1,4 linkages. Here, to create designed slowly digestible carbohydrates, the structure of waxy corn starch (WCS) was modified using a known branching enzyme alone (BE) and an in combination with β-amylase (BA) to increase further the α-1,6 branching ratio. The digestibility of the enzymatically synthesized products was investigated using α-amylase and four recombinant mammalian mucosal α-glucosidases. Enzyme-modified products (BE-WCS and BEBA-WCS) had increased percentage of α-1,6 linkages (WCS: 5.3%, BE-WCS: 7.1%, and BEBA-WCS: 12.9%), decreased weight-average molecular weight (WCS: 1.73×108 Da, BE-WCS: 2.76×105 Da, and BEBA-WCS 1.62×105 Da), and changes in linear chain distributions (WCS: 21.6, BE-WCS: 16.9, BEBA-WCS: 12.2 DPw). Hydrolysis by human pancreatic α-amylase resulted in an increase in the amount of branched α-limit dextrin from 26.8% (WCS) to 56.8% (BEBA-WCS). The α-amylolyzed samples were hydrolyzed by the individual α-glucosidases (100 U) and glucogenesis decreased with all as the branching ratio increased. This is the first report showing that hydrolysis rate of the mammalian mucosal α-glucosidases is limited by the amount of branched α-limit dextrin. When enzyme-treated materials were gavaged to rats, the level of postprandial blood glucose at 60 min from BEBA-WCS was significantly higher than for WCS or BE-WCS. Thus, highly branched glucan structures modified by BE and BA had a comparably slow digesting property both in vitro and in vivo. Such highly branched α-glucans show promise as a food ingredient to control postprandial glucose levels and to attain extended glucose release.
PMCID: PMC3615069  PMID: 23565164
22.  The Cellular Generation and a New Risk Environment: Implications for Texting-Based Sexual Health Promotion Interventions among Minority Young Men Who Have Sex with Men 
African American and Latino young men who have sex with men (YMSM) are at the forefront of the U.S. HIV epidemic. As members of the “cellular generation,” these youth are very likely to use text messaging; yet, relatively little research has explored use of text messaging as a tool for sexual health promotion, particularly among racial ethnic minorities who are also sexual minorities. We report on the results of ten focus groups conducted among African American and Latino YMSM, aged 18–25, regarding their current texting practices and the feasibility/acceptability of text messaging as a means of conducting sexual health promotion. Our analyses revealed four main themes around their texting behaviors, texting preferences, perceived advantages/disadvantages of texting, and the “etiquette” of texting. We consider implications of these findings for the development of texting-based sexual health promotion interventions, particularly in conjunction with other existing interventions operating in a new risk environment.
PMCID: PMC3540519  PMID: 23304294
23.  Structure, Mechanism, and Substrate Specificity of Kynureninase 
Biochimica et biophysica acta  2010;1814(11):1481-1488.
The kynurenine pathway is the major route for tryptophan catabolism in animals and some fungi and bacteria. The procaryotic enzyme preferentially reacts with L-kynurenine, while eucaryotic kynureninases exhibit higher activity with 3-hydroxy-L-kynurenine. Crystallography of kynureninases from Pseudomonas fluorescens (PfKyn) and Homo sapiens (HsKyn) shows that the active sites are nearly identical, except that His-102, Asn-333, and Ser-332 in HsKyn are replaced by Trp-64, Thr-282 and Gly-281 in PfKyn. Site-directed mutagenesis of HsKyn shows that these residues are, at least in part, responsible for the differences in substrate specificity, since the H102W/S332G/N333T triple mutant shows activity with kynurenine but not 3-hydroxykynurenine. PfKyn is strongly inhibited by analogues of a proposed gem-diolate intermediate, dihydrokynurenine and S-(2-aminophenyl)-L-cysteine S,S-dioxide, with Ki values in the low nM range. Stopped-flow kinetic experiments show that a transient quinonoid intermediate is formed on mixing, which decays to a ketimine at 740 s−1. Quench experiments show that anthranilate, the first product, is formed in a stoichiometric burst at 50 s−1, and thus the rate-determining step in the steady state is the release of the second product, L-Ala. β-Benzoylalanine is also a good substrate for PfKyn, but does not show a burst of benzoate formation, indicating that the rate-determining step for this substrate is benzoate release. A Hammett plot of rate constants for substituted β-benzoylalanines is non-linear, suggesting that carbonyl hydration is rate-determining for electron-donating groups, but Cβ-Cγ cleavage is rate-determining for electron-withdrawing groups.
PMCID: PMC3102132  PMID: 21167323
Pyridoxal-5′-phosphate; tryptophan; reaction mechanism; crystallography; mutagenesis
24.  Vagal intramuscular array afferents form complexes with interstitial cells of Cajal in gastrointestinal smooth muscle: Analogues of muscle spindle organs? 
Neuroscience  2011;186:188-200.
Intramuscular arrays (IMAs), vagal mechanoreceptors that innervate gastrointestinal smooth muscle, have not been completely described structurally or functionally. To delineate more fully the architecture of IMAs and to consider the structure-function implications of the observations, the present experiment examined the organization of the IMA terminal arbors and the accessory tissue elements of those arbors. IMA terminal fields, labeled by injection of biotinylated dextran into the nodose ganglia, were examined in whole mounts of rat gastric smooth muscle double-labeled with immunohistochemistry for interstitial cells of Cajal (ICCs; c-Kit) and/or inputs of different neuronal efferent transmitter (markers: TH, VChAT, and NOS) or afferent neuropeptidergic (CGRP) phenotypes. IMAs make extensive varicose and lamellar contacts with ICCs. In addition, axons of the multiple efferent and afferent phenotypes examined converge and articulate with IMA terminal arbors innervating ICCs. This architecture is consistent with the hypothesis that IMAs, or the multiply innervated IMA-ICC complexes they form, can function as stretch receptors. The tissue organization is also consonant with the proposal that those units can operate as functional analogues of muscle spindle organs. For electrophysiological assessments of IMA functions, experiments will need protocols that preserve both the complex architecture and the dynamic operations of IMA-ICC complexes.
PMCID: PMC3110524  PMID: 21530617
mechanosensitive afferents; mechanoreceptors; smooth muscle; stomach; stretch receptors; vagus nerve
25.  Updated Systematic Review and Meta-Analysis of the Performance of Risk Prediction Rules in Children and Young People with Febrile Neutropenia 
PLoS ONE  2012;7(5):e38300.
Febrile neutropenia is a common and potentially life-threatening complication of treatment for childhood cancer, which has increasingly been subject to targeted treatment based on clinical risk stratification. Our previous meta-analysis demonstrated 16 rules had been described and 2 of them subject to validation in more than one study. We aimed to advance our knowledge of evidence on the discriminatory ability and predictive accuracy of such risk stratification clinical decision rules (CDR) for children and young people with cancer by updating our systematic review.
The review was conducted in accordance with Centre for Reviews and Dissemination methods, searching multiple electronic databases, using two independent reviewers, formal critical appraisal with QUADAS and meta-analysis with random effects models where appropriate. It was registered with PROSPERO: CRD42011001685.
We found 9 new publications describing a further 7 new CDR, and validations of 7 rules. Six CDR have now been subject to testing across more than two data sets. Most validations demonstrated the rule to be less efficient than when initially proposed; geographical differences appeared to be one explanation for this.
The use of clinical decision rules will require local validation before widespread use. Considerable uncertainty remains over the most effective rule to use in each population, and an ongoing individual-patient-data meta-analysis should develop and test a more reliable CDR to improve stratification and optimise therapy. Despite current challenges, we believe it will be possible to define an internationally effective CDR to harmonise the treatment of children with febrile neutropenia.
PMCID: PMC3365042  PMID: 22693615

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