Imaging activation of peptidergic spinal afferent varicosities within visceral organs using novel CGRP{alpha}-mCherry reporter mice

In vertebrates, visceral pain from internal organs is detected by spinal afferents, whose cell bodies lie in dorsal root ganglia (DRG). Until now, all recordings from spinal afferents have been restricted to recording transmission of action potentials along axons, or from cell bodies lying outside their target organ, which is not where sensory transduction occurs. Our aim was to record directly from a major class of spinal afferent within visceral organs, where transduction of sensory stimuli into action potentials occurs. Using novel calcitonin gene-related peptide (CGRP)α reporter mice, DRG neurons expressed mCherry, including nerve axons within viscera. In colon, a minority of total CGRP immunoreactivity was attributed CGRPα. In isolated unstretched colon, calcium imaging from CGRPα-expressing varicose axons did not detect resolvable calcium transients. However, noxious levels of maintained circumferential stretch to the colon induced repetitive calcium transients simultaneously in multiple neighboring varicosities along single mCherry-expressing axons. Discrete varicosities could generate unitary calcium transients independently of neighboring varicosities. However, axons expressing mCherry only generated coordinated calcium transients when accompanied by simultaneous activation of multiple varicosities along that axon. Simultaneous imaging from different classes of myenteric neurons at the same time as mCherry-expressing axons revealed coordinated calcium transients in multiple myenteric neurons, independent of activity in mCherry-expressing axons. CGRPα-expressing axon terminals preferentially responded to heat, capsaicin, and low pH. We show that direct recordings can be made from the major class of peptidergic spinal afferent that contributes to visceral nociception. This approach can provide powerful insights into transduction of stimuli in viscera.

From: Spencer, N. J., Sorensen, J., Travis, L., Wiklendt, L., Costa, M., Hibberd, T. http://ajpgi.physiology.org/cgi/content/abstract/311/5/G880?rss=1

A novel transgenic mouse model of lysosomal storage disorder

Knockout technology has proven useful for delineating functional roles of specific genes. Here we describe and provide an explanation for striking pathology that occurs in a subset of genetically engineered mice expressing a rat Ca_Vβ2a transgene under control of the cardiac α-myosin heavy chain promoter. Lesions were limited to mice homozygous for transgene and independent of native Cacnb2 genomic copy number. Gross findings included an atrophied pancreas; decreased adipose tissue; thickened, orange intestines; and enlarged liver, spleen, and abdominal lymph nodes. Immune cell infiltration and cell engulfment by macrophages were associated with loss of pancreatic acinar cells. Foamy macrophages diffusely infiltrated the small intestine's lamina propria, while similar macrophage aggregates packed liver and splenic red pulp sinusoids. Periodic acid-Schiff-positive, diastase-resistant, iron-negative, Oil Red O-positive, and autofluorescent cytoplasm was indicative of a lipid storage disorder. Electron microscopic analysis revealed liver sinusoids distended by clusters of macrophages containing intracellular myelin "swirls" and hepatocytes with enlarged lysosomes. Additionally, build up of cholesterol, cholesterol esters, and triglycerides, along with changes in liver metabolic enzyme levels, were consistent with a lipid processing defect. Because of this complex pathology, we examined the transgene insertion site. Multiple transgene copies inserted into chromosome 19; at this same site, an approximate 180,000 base pair deletion occurred, ablating cholesterol 25-hydroxylase and partially deleting lysosomal acid lipase and CD95. Loss of gene function can account for the altered lipid processing, along with hypertrophy of the immune system, which define this phenotype, and serendipitously provides a novel mouse model of lysosomal storage disorder.

From: Ortiz-Miranda, S., Ji, R., Jurczyk, A., Aryee, K.-E., Mo, S., Fletcher, T., Shaffer, S. A., Greiner, D. L., Bortell, R., Gregg, R. G., Cheng, A., Hennings, L. J., Rittenhouse, A. R. http://ajpgi.physiology.org/cgi/content/abstract/311/5/G903?rss=1

Functional physiology of the human terminal antrum defined by high-resolution electrical mapping and computational modeling

High-resolution (HR) mapping has been used to study gastric slow-wave activation; however, the specific characteristics of antral electrophysiology remain poorly defined. This study applied HR mapping and computational modeling to define functional human antral physiology. HR mapping was performed in 10 subjects using flexible electrode arrays (128–192 electrodes; 16–24 cm²) arranged from the pylorus to mid-corpus. Anatomical registration was by photographs and anatomical landmarks. Slow-wave parameters were computed, and resultant data were incorporated into a computational fluid dynamics (CFD) model of gastric flow to calculate impact on gastric mixing. In all subjects, extracellular mapping demonstrated normal aboral slow-wave propagation and a region of increased amplitude and velocity in the prepyloric antrum. On average, the high-velocity region commenced 28 mm proximal to the pylorus, and activation ceased 6 mm from the pylorus. Within this region, velocity increased 0.2 mm/s per mm of tissue, from the mean 3.3 ± 0.1 mm/s to 7.5 ± 0.6 mm/s (P < 0.001), and extracellular amplitude increased from 1.5 ± 0.1 mV to 2.5 ± 0.1 mV (P < 0.001). CFD modeling using representative parameters quantified a marked increase in antral recirculation, resulting in an enhanced gastric mixing, due to the accelerating terminal antral contraction. The extent of gastric mixing increased almost linearly with the maximal velocity of the contraction. In conclusion, the human terminal antral contraction is controlled by a short region of rapid high-amplitude slow-wave activity. Distal antral wave acceleration plays a major role in antral flow and mixing, increasing particle strain and trituration.

From: Berry, R., Miyagawa, T., Paskaranandavadivel, N., Du, P., Angeli, T. R., Trew, M. L., Windsor, J. A., Imai, Y., O'Grady, G., Cheng, L. K. http://ajpgi.physiology.org/cgi/content/abstract/311/5/G895?rss=1

Acetylcholine-producing T cells in the intestine regulate antimicrobial peptide expression and microbial diversity

The cholinergic anti-inflammatory pathway reduces systemic tumor necrosis factor (TNF) via acetylcholine-producing memory T cells in the spleen. These choline acetyltransferase (ChAT)-expressing T cells are also found in the intestine, where their function is unclear. We aimed to characterize these cells in mouse and human intestine and delineate their function. We made use of the ChAT-enhanced green fluorescent protein (eGFP) reporter mice. CD4^Cre mice were crossed to ChAT^fl/fl mice to achieve specific deletion of ChAT in CD4⁺ T cells. We observed that the majority of ChAT-expressing T cells in the human and mouse intestine have characteristics of Th17 cells and coexpress IL17A, IL22, and RORC. The generation of ChAT-expressing T cells was skewed by dendritic cells after activation of their adrenergic receptor β₂. To evaluate ChAT T cell function, we generated CD4-specific ChAT-deficient mice. CD4ChAT^–/– mice showed a reduced level of epithelial antimicrobial peptides lysozyme, defensin A, and ang4, which was associated with an enhanced bacterial diversity and richness in the small intestinal lumen in CD4ChAT^–/– mice. We conclude that ChAT-expressing T cells in the gut are stimulated by adrenergic receptor activation on dendritic cells. ChAT-expressing T cells may function to mediate the host AMP secretion, microbial growth and expansion.

From: Dhawan, S., De Palma, G., Willemze, R. A., Hilbers, F. W., Verseijden, C., Luyer, M. D., Nuding, S., Wehkamp, J., Souwer, Y., de Jong, E. C., Seppen, J., van den Wijngaard, R. M., Wehner, S., Verdu, E., Bercik, P., de Jonge, W. J. http://ajpgi.physiology.org/cgi/content/abstract/311/5/G920?rss=1

Measurement of strains experienced by viscerofugal nerve cell bodies during mechanosensitive firing using digital image correlation

Mechanosensory neurons detect physical events in the local environments of the tissues that they innervate. Studies of mechanosensitivity of neurons or nerve endings in the gut have related their firing to strain, wall tension, or pressure. Digital image correlation (DIC) is a technique from materials engineering that can be adapted to measure the local physical environments of afferent neurons at high resolution. Flat-sheet preparations of guinea pig distal colon were set up with arrays of tissue markers in vitro. Firing of single viscerofugal neurons was identified in extracellular colonic nerve recordings. The locations of viscerofugal nerve cell bodies were inferred by mapping firing responses to focal application of the nicotinic receptor agonist 1,1-dimethyl-4-phenylpiperazinium iodide. Mechanosensory firing was recorded during load-evoked uniaxial or biaxial distensions. Distension caused movement of surface markers which was captured by video imaging. DIC tracked the markers, interpolating the mechanical state of the gut at the location of the viscerofugal nerve cell body. This technique revealed heterogeneous load-evoked strain within preparations. Local strains at viscerofugal nerve cell bodies were usually smaller than global strain measurements and correlated more closely with mechanosensitive firing. Both circumferential and longitudinal strain activated viscerofugal neurons. Simultaneous loading in circumferential and longitudinal axes caused the highest levels of viscerofugal neuron firing. Multiaxial strains, reflecting tissue shearing and changing area, linearly correlated with mechanosensory firing of viscerofugal neurons. Viscerofugal neurons were mechanically sensitive to both local circumferential and local longitudinal gut strain, and appear to lack directionality in their stretch sensitivity.

From: Palmer, G., Hibberd, T. J., Roose, T., Brookes, S. J. H., Taylor, M. http://ajpgi.physiology.org/cgi/content/abstract/311/5/G869?rss=1

Hepatic aberrant glycosylation by N-acetylglucosaminyltransferase V accelerates HDL assembly

Glycosylation is involved in various pathophysiological conditions. N-Acetylglucosaminyltransferase V (GnT-V), catalyzing β1–6 branching in asparagine-linked oligosaccharides, is one of the most important glycosyltransferases involved in cancer and the immune system. Recent findings indicate that aberrant N-glycan structure can modify lipid metabolism. In this study, we investigated the effects of aberrant glycosylation by GnT-V on high-density lipoprotein cholesterol (HDL) assembly. We used GnT-V transgenic (Tg) mice and GnT-V Hep3B cell (human hepatoma cell line) transfectants. The study also included 96 patients who underwent medical health check-ups. Total serum cholesterol levels, particularly HDL-cholesterol (HDL-C) levels, were significantly increased in Tg vs. wild-type (WT) mice. Hepatic expression of apolipoprotein AI (ApoAI) and ATP-binding cassette subfamily A member 1 (ABCA1), two important factors in HDL assembly, were higher in Tg mice compared with WT mice. ApoAI and ABCA1 were also significantly elevated in GnT-V transfectants compared with mock-transfected cells. Moreover, ApoAI protein in the cultured media of GnT-V transfectants was significantly increased. Finally, we found a strong correlation between serum GnT-V activity and HDL-C concentration in human subjects. Multivariate logistic analyses demonstrated that GnT-V activity was an independent and significant determinant for serum HDL-C levels even adjusted with age and gender differences. Further analyses represented that serum GnT-V activity had strong correlation especially with the large-size HDL particle concentration. These findings indicate that enhanced hepatic GnT-V activity accelerated HDL assembly and could be a novel mechanism for HDL synthesis.

From: Kamada, Y., Kida, S., Hirano, K.-i., Yamaguchi, S., Suzuki, A., Hashimoto, C., Kimura, A., Sato, M., Fujii, H., Sobajima, T., Yamamoto, A., Ebisutani, Y., Takamatsu, S., Shinzaki, S., Yoshida, Y., Yamada, M., Nagasaka, H., Takehara, T., Miyoshi, E. http://ajpgi.physiology.org/cgi/content/abstract/311/5/G859?rss=1

TLR9 activation suppresses inflammation in response to Helicobacter pylori infection

Helicobacter pylori (H. pylori) induces chronic gastritis in humans, and infection can persist for decades. One H. pylori strain-specific constituent that augments disease risk is the cag pathogenicity island. The cag island encodes a type IV secretion system (T4SS) that translocates DNA into host cells. Toll-like receptor 9 (TLR9) is an innate immune receptor that detects hypo-methylated CpG DNA motifs. In this study, we sought to define the role of the H. pylori cag T4SS on TLR9-mediated responses in vivo. H. pylori strain PMSS1 or its cagE^– mutant, which fails to assemble a T4SS, were used to infect wild-type or Tlr9^–/– C57BL/6 mice. PMSS1-infected Tlr9^–/– mice developed significantly higher levels of inflammation, despite similar levels of colonization density, compared with PMSS1-infected wild-type mice. These changes were cag dependent, as both mouse genotypes infected with the cagE^– mutant only developed minimal inflammation. Tlr9^–/– genotypes did not alter the microbial phenotypes of in vivo-adapted H. pylori strains; therefore, we examined host immunological responses. There were no differences in levels of T_H1 or T_H2 cytokines in infected mice when stratified by host genotype. However, gastric mucosal levels of IL-17 were significantly increased in infected Tlr9^–/– mice compared with infected wild-type mice, and H. pylori infection of IL-17A^–/– mice concordantly led to significantly decreased levels of gastritis. Thus loss of Tlr9 selectively augments the intensity of IL-17-driven immune responses to H. pylori in a cag T4SS-dependent manner. These results suggest that H. pylori utilizes the cag T4SS to manipulate the intensity of the host immune response.

From: Varga, M. G., Piazuelo, M. B., Romero-Gallo, J., Delgado, A. G., Suarez, G., Whitaker, M. E., Krishna, U. S., Patel, R. V., Skaar, E. P., Wilson, K. T., Algood, H. M. S., Peek, R. M. http://ajpgi.physiology.org/cgi/content/abstract/311/5/G852?rss=1

Could loneliness be an early sign of Alzheimer's?

People with "biomarkers" for the brain disease were more likely to feel socially detached, a new study finds

From: http://www.cbsnews.com/news/could-loneliness-be-an-early-sign-of-alzheimers/

Scientists study if Pap smear could spot birth defects

Cells captured during this common test in early pregnancy could one day help spot genetic defects early on

From: http://www.cbsnews.com/news/pap-smear-test-early-pregnancy-spot-birth-defects/

Heavy Drinking May Mean Hefty Health Tab Later

Study suggests alcohol might harm brain, body even if one stops abusing by age 30

From: http://www.webmd.com/mental-health/addiction/news/20161102/heavy-drinking-while-young-may-mean-hefty-health-tab-later?src=RSS_PUBLIC

​How young should kids get screened for obesity?

The latest guidelines recommend counseling to help children manage weight

From: http://www.cbsnews.com/news/kids-age-6-and-up-should-be-screened-for-obesity/

Live Webinar: Hypertrophic Cardiomyopathy and the Surgical Treatment Apical Myectomy

From: Mayo Clinic http://www.youtube.com/watch?v=H7gINCUxmS4

Could Loneliness Be an Early Sign of Alzheimer's?

People with 'biomarkers' for the brain disease were more likely to feel socially detached, study finds

From: http://www.webmd.com/alzheimers/news/20161102/could-loneliness-be-an-early-sign-of-alzheimers?src=RSS_PUBLIC

Menopause and a Decline in Intimacy

Researchers identify timing, but it can vary by race and ethnicity

From: http://www.webmd.com/menopause/news/20161102/menopause-and-a-decline-in-intimacy?src=RSS_PUBLIC

The confusing state of food allergy labels

Food labels warning about allergens aren't required by law, and the messages are often misunderstood

From: http://www.cbsnews.com/news/the-confusing-state-of-food-allergy-labels/