Iron deficiency linked to altered bile acid metabolism promotes Helicobacter pylori-induced inflammation-driven gastric carcinogenesis

Gastric carcinogenesis is mediated by complex interactions among Helicobacter pylori, host, and environmental factors. Here, we demonstrate that H. pylori augmented gastric injury in INS-GAS mice under iron-deficient conditions. Mechanistically, these phenotypes were not driven by alterations in the gastric microbiota; however, discovery-based and targeted metabolomics revealed that bile acids were significantly altered in H. pylori-infected mice with iron deficiency, with significant upregulation of deoxycholic acid (DCA), a carcinogenic bile acid. The severity of gastric injury was further augmented when H. pylori-infected mice were treated with DCA, and, in vitro, DCA increased translocation of the H. pylori oncoprotein CagA into host cells. Conversely, bile acid sequestration attenuated H. pylori-induced injury under conditions of iron deficiency. To translate these findings to human populations, we evaluated the association between bile acid sequestrant use and gastric cancer risk in a large human cohort. Among 416,885 individuals, a significant dose-dependent reduction in risk was associated with cumulative bile acid sequestrant use. Further, expression of the bile acid receptor transmembrane G protein-coupled bile acid receptor 5 (TGR5) paralleled the severity of carcinogenic lesions in humans. These data demonstrate that increased H. pylori-induced injury within the context of iron deficiency is tightly linked to altered bile acid metabolism, which may promote gastric carcinogenesis.

Secondary recurrent carotid stenosis

PURPOSE

Recurrent carotid stenosis after carotid endarterectomy has been extensively reported. The occurrence, however, of another ipsilateral restenosis that requires a third carotid operation is rare. The purpose of this study was to evaluate possible risk factors and the most efficacious management of the patient with "secondary" recurrent carotid stenosis.

METHODS

A survey of the Southern Association for Vascular Surgery was performed, and 31 patients who had had surgery for secondary recurrent carotid stenosis were identified.

RESULTS

The mean interval between the recurrent stenosis operation and secondary recurrent carotid stenosis was 39.8 months (range, 9 to 83 months). At the third operation, 21 patients underwent carotid patch angioplasty and 10 underwent carotid resection with an interposition saphenous vein graft. No postoperative strokes or deaths occurred; three patients (10%) had a peripheral nerve injury. Nine early (< 24 mo) secondary recurrent carotid stenoses occurred, and these patients underwent patch angioplasty. Twenty-three female, cigarette-smoking patients and 20 patients with elevated lipid levels had early restenosis and were identified as being at high risk for the development of another stenosis. A fourth significant stenosis developed in five of these high-risk patients who had saphenous vein patch angioplasty at their third carotid operation; eight other high-risk patients had carotid resection with an interposition saphenous vein graft, and no other stenosis developed.

CONCLUSION

Patients who have secondary recurrent carotid stenoses can safely undergo a third carotid operation. Female habitual smokers with elevated lipid levels and an early restenosis appear to be at high risk of secondary recurrent carotid stenoses. When surgery is necessary, carotid resection with an interposition saphenous vein graft appears more durable than patch angioplasty.

Calponin and smooth muscle regulation

Calponin has been implicated in the regulation of smooth muscle contraction as a result of its ability to inhibit the actin-activated Mg ATPase of smooth muscle myosin. This inhibitory effect is abolished by phosphorylation of calponin by Ca2+/calmodulin-dependent protein kinase II or protein kinase C, and restored following dephosphorylation by a type 2A protein phosphatase. Confocal immunofluorescent images of isolated smooth muscle cells colabeled with antibodies to calponin and actin or to calponin and tropomyosin indicate that calponin is present on thin filaments throughout the cell cytoplasm. Both calponin phosphorylation and myosin light chain phosphorylation increased in intact smooth muscle tissue strips when they contracted in response to carbachol or the phosphatase inhibitor okadaic acid. These results support the hypothesis that calponin phosphorylation-dephosphorylation plays a role in regulating smooth muscle contraction.

Management of coexistent carotid and coronary artery disease

Simultaneous coronary artery bypass grafting (CABG) and carotid endarterectomy (CE) were done on 133 patients over an 8-year period. Twenty-seven patients (20%) had previous transient ischemic attacks (TIAs), 12 (9%) had previous strokes, and the remainder (71%) were asymptomatic. All asymptomatic patients had greater than 85% stenosis of the internal carotid artery demonstrated by noninvasive ultrasonography and four-vessel angiography. CE was performed prior to the sternotomy for coronary artery bypass, under the same anesthesia. Nineteen patients had bilateral carotid artery disease. Postoperatively, three patients (2.3%) suffered strokes, an additional three patients (2.3%) suffered transient upper extremity weakness, and one patient from each of these groups died. There were no postoperative strokes or TIAs in patients with bilateral carotid artery disease. Average length of hospital stay was 10 days. Our experience leads us to conclude that the morbidity and mortality of the simultaneous procedure are not affected by bilateral carotid artery disease. In patients with symptomatic coronary artery disease and symptomatic carotid artery disease or asymptomatic carotid artery disease with a high-grade stenosis, we think that simultaneous repair of both lesions should be done.

Characterization and confocal imaging of calponin in gastrointestinal smooth muscle

Calponin isolated from chicken gizzard smooth muscle binds in vitro to actin in a Ca(2+)-independent manner and thereby inhibits the actin-activated Mg(2+)-adenosinetriphosphatase of smooth muscle myosin. This inhibition is relieved when calponin is phosphorylated by protein kinase C or Ca2+/calmodulin-dependent protein kinase II, suggesting that calponin is involved in thin filament-associated regulation of smooth muscle contraction. To further examine this possibility, calponin was isolated from toad stomach smooth muscle, characterized biochemically, and localized in intact isolated cells. Toad stomach calponin had the same basic biochemical properties as calponin from other sources. Confocal immunofluorescence microscopy revealed that calponin in intact smooth muscle cells was localized to long filamentous structures that were colabeled by antibodies to actin or tropomyosin. Preservation of the basic biochemical properties of calponin from species to species suggests that these properties are relevant for its in vivo function. Its colocalization with actin and tropomyosin indicates that calponin is associated with the thin filament in intact smooth muscle cells.

Carotid surgery in the community hospital: 467 consecutive operations

Over a 12-year period, 467 consecutive operations for carotid disease were performed on 424 patients in community hospitals. Of all the patients, 0.2% died within 30 days of surgery and 3% had a stroke within 30 days. One third of these strokes were disabling. No cerebral monitoring equipment was used and an indwelling carotid shunt was only rarely used.