Patterns of Internet use by gastroenterologists in the management and education of patients with inflammatory bowel disease.

AIMS: To define the patterns of Internet use among physicians who treat inflammatory bowel disease (IBD) and physicians' perceptions of their patients' Internet use. METHODS: An online survey about physician and patient use of the Internet was created and e-mailed to gastroenterologists nationwide. Surveys were distributed and collected via an online database and a subsequent statistical analysis was performed. RESULTS: Of the 1000 e-mail invitations sent to practicing gastroenterologists in the United States, 223 participants (22.3%) completed the survey. A total of 183 (82.1%) physicians reported using an Internet-based reference to assist them in deriving management strategies for their patients with IBD, with the most commonly utilized resource being UpToDate followed by PubMed and the Crohn's and Colitis Foundation of America Web site. Although nearly 80% of gastroenterologists believed that using the Internet helped them facilitate clinical discussions, 183 participants (82.1%) believed that inaccurate information found online could sometimes result in increased clinic time because physicians must spend more time dispelling misleading information. CONCLUSIONS: Despite a study design biased toward selecting gastroenterologists who commonly used the Internet, we demonstrated that only 60% of the providers routinely refer their patients to the Internet. This underscores the fact that it is important to have a centralized "physician-certified" online resource to which physicians could readily refer their patients to navigate through various disease-specific resources without concern that their patients are receiving unreliable or misleading information.

Potassium-chloride cotransporter 3 interacts with Vav2 to synchronize the cell volume decrease response with cell protrusion dynamics.

Loss-of-function of the potassium-chloride cotransporter 3 (KCC3) causes hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC), a severe neurodegenerative disease associated with defective midline crossing of commissural axons in the brain. Conversely, KCC3 over-expression in breast, ovarian and cervical cancer is associated with enhanced tumor cell malignancy and invasiveness. We identified a highly conserved proline-rich sequence within the C-terminus of the cotransporter which when mutated leads to loss of the KCC3-dependent regulatory volume decrease (RVD) response in Xenopus Laevis oocytes. Using SH3 domain arrays, we found that this poly-proline motif is a binding site for SH3-domain containing proteins in vitro. This approach identified the guanine nucleotide exchange factor (GEF) Vav2 as a candidate partner for KCC3. KCC3/Vav2 physical interaction was confirmed using GST-pull down assays and immuno-based experiments. In cultured cervical cancer cells, KCC3 co-localized with the active form of Vav2 in swelling-induced actin-rich protruding sites and within lamellipodia of spreading and migrating cells. These data provide evidence of a molecular and functional link between the potassium-chloride co-transporters and the Rho GTPase-dependent actin remodeling machinery in RVD, cell spreading and cell protrusion dynamics, thus providing new insights into KCC3's involvement in cancer cell malignancy and in corpus callosum agenesis in HMSN/ACC.

Loss of neuronal potassium/chloride cotransporter 3 (KCC3) is responsible for the degenerative phenotype in a conditional mouse model of hereditary motor and sensory neuropathy associated with agenesis of the corpus callosum.

Disruption of the potassium/chloride cotransporter 3 (KCC3), encoded by the SLC12A6 gene, causes hereditary motor and sensory neuropathy associated with agenesis of the corpus callosum (HMSN/ACC), a neurodevelopmental and neurodegenerative disorder affecting both the peripheral nervous system and CNS. However, the precise role of KCC3 in the maintenance of ion homeostasis in the nervous system and the pathogenic mechanisms leading to HMSN/ACC remain unclear. We established two Slc12a6 Cre/LoxP transgenic mouse lines expressing C-terminal truncated KCC3 in either a neuron-specific or ubiquitous fashion. Our results suggest that neuronal KCC3 expression is crucial for axon volume control. We also demonstrate that the neuropathic features of HMSN/ACC are predominantly due to a neuronal KCC3 deficit, while the auditory impairment is due to loss of non-neuronal KCC3 expression. Furthermore, we demonstrate that KCC3 plays an essential role in inflammatory pain pathways. Finally, we observed hypoplasia of the corpus callosum in both mouse mutants and a marked decrease in axonal tracts serving the auditory cortex in only the general deletion mutant. Together, these results establish KCC3 as an important player in both central and peripheral nervous system maintenance.

Transit defect of potassium-chloride Co-transporter 3 is a major pathogenic mechanism in hereditary motor and sensory neuropathy with agenesis of the corpus callosum.

Missense and protein-truncating mutations of the human potassium-chloride co-transporter 3 gene (KCC3) cause hereditary motor and sensory neuropathy with agenesis of the corpus callosum (HMSN/ACC), which is a severe neurodegenerative disease characterized by axonal dysfunction and neurodevelopmental defects. We previously reported that KCC3-truncating mutations disrupt brain-type creatine kinase-dependent activation of the co-transporter through the loss of its last 140 amino acids. Here, we report a novel and more distal HMSN/ACC-truncating mutation (3402C → T; R1134X) that eliminates only the last 17 residues of the protein. This small truncation disrupts the interaction with brain-type creatine kinase in mammalian cells but also affects plasma membrane localization of the mutant transporter. Although it is not truncated, the previously reported HMSN/ACC-causing 619C → T (R207C) missense mutation also leads to KCC3 loss of function in Xenopus oocyte flux assay. Immunodetection in Xenopus oocytes and in mammalian cultured cells revealed a decreased amount of R207C at the plasma membrane, with significant retention of the mutant proteins in the endoplasmic reticulum. In mammalian cells, curcumin partially corrected these mutant protein mislocalizations, with more protein reaching the plasma membrane. These findings suggest that mis-trafficking of mutant protein is an important pathophysiological feature of HMSN/ACC causative KCC3 mutations.

TNF-alpha antagonism with etanercept decreases glucose and increases the proportion of high molecular weight adiponectin in obese subjects with features of the metabolic syndrome.

CONTEXT AND OBJECTIVE: Obesity is associated with activation of the TNF-α system, increased inflammatory markers, and insulin resistance. Although studies in rodents suggest that attenuation of TNF activity improves glucose homeostasis, the effect of prolonged inhibition of TNF-α with etanercept on inflammation and glucose homeostasis in a human model of obesity is not known. DESIGN AND PARTICIPANTS: Forty obese subjects with features of metabolic syndrome were randomized to etanercept or placebo, 50 mg twice weekly for 3 months, followed by 50 mg once weekly for 3 months. OUTCOME MEASURES: Subjects underwent oral glucose tolerance testing and measurement of serum inflammatory biomarkers and adipokines. Subcutaneous fat biopsy was performed in a subset for measurement of adipokine and TNF-α mRNA expression. RESULTS: Visceral adiposity was significantly associated with serum concentrations of TNF receptor 1 (TNFR1), TNFR2, and vascular cell adhesion molecule-1 and adipose tissue expression of TNF-α and SOCS-3 (all P < 0.05). Insulin resistance as assessed by homeostasis model assessment was significantly associated with TNFR1, C-reactive protein, IL-6, and soluble intracellular adhesion molecule-1 (sICAM-1) (all P < 0.05). Etanercept significantly improved fasting glucose (treatment effect vs. placebo over 6 months, -10.8 ± 4.4%, P = 0.02). Etanercept also increased the ratio of high molecular weight adiponectin to total adiponectin (+22.1 ± 9.2% vs. placebo, P = 0.02), and decreased levels of sICAM-1 (-11 ± 2% vs. placebo, P < 0.0001). In contrast, body composition, lipids, C-reactive protein, and IL-6 were unchanged after 6 months. CONCLUSIONS: Prolonged therapy with etanercept improved fasting glucose, increased the ratio of high molecular weight to total adiponectin, and decreased sICAM-1 in obese subjects with abnormal glucose homeostasis and significant subclinical inflammation.