1. Discharges of lumbar dorsal horn neurons were evoked by noxious radiant skin heating, and inhibition of the heat-evoked responses by stimulation of the mesencephalic periaqueductal gray was investigated in N2O-anesthetized cats. 2. Thirty-seven units selected on the basis of receiving afferent C-fiber input from the posterior tibial and/or superficial peroneal nerves responded vigorously to 50 degrees C heating of the plantar surface of the ipsilateral hindpaw. All discharges were inhibited by periaqueductal gray stimulation (PAGS) at current strengths of 300--900 microA; the mean threshold for inhibition was 167 microamperemeter. The mean frequency of the inhibited discharge was 39% of the control response. 3. Effective PAGS sites were distributed throughout the ventral PAG bilaterally. Stimulus current-distance estimates indicate that small (0.5--1.2 mm diameter) volumes of tissue within the PAG were stimulated. 4. A monotonic relationship between temperature and unitary discharge was found for skin heating from threshold to about 50 degrees C. PAGS resulted in a decrease in the slope of the curve plotting discharge against temperature, without altering the threshold. 5. Inhibition of the heat-evoked discharges rarely outlasted the PAGS. 6. Possible neural substrates for descending inhibition and correlates with neural mechanisms of analgesia are discussed.

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Objective Few studies have reported the influence of clinical background factors on the outcome of Helicobacter pylori eradication therapy in primary care practice. We aimed to determine which clinical background factors influence the outcome of eradication therapy in a primary care setting. Methods This was a retrospective study of patients who received H pylori eradication therapy at Higashiohmi City Gamo Medical Center, Shiga, Japan, from January 2012 to December 2015. We investigated clinical background factors associated with success, failure, and self‐interruption of H pylori eradication therapy: patients’ age, gender, first‐ or second‐line treatment, reasons for receiving gastroenterological endoscopic examination, method of drug administration, and attending physicians’ age and their specialties. Results There were 369 patients (208 females, 161 male), with a mean age of 59 years (range 30‐88 years). The middle‐aged group (50‐69 years) was associated with successful eradication therapy compared with the young group (30‐49 years). The elderly group (>70 years) was associated with eradication therapy failure compared with the middle‐aged group. The young group was associated with self‐interruption of eradication therapy. There was a marginally significant association between male patients and self‐interruption. Older attending physicians (>50 years) were also associated with failure compared with younger physicians. There was no difference in outcome of eradication therapy between generalists and gastroenterology specialists. Conclusion We have identified clinical factors associated with success, failure, and self‐interruption of H pylori eradication therapy in a primary care setting.

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