Francis Seow

The 13C-caffeine breath test distinguishes significant fibrosis in chronic hepatitis B and reflects response to lamivudine therapy

Background : The 13C‐caffeine breath test is a non‐invasive, quantitative test of liver function.

c-Fos immunoreactivity in the brain after esophageal acid stimulation

The goal of this study was to use c-Fos immunohistochemistry to establish a rat model for studying the central projection of the esophageal afferent neurons during acid exposure. A cannula was placed in the esophagus of anesthetized Wistar rats with the tip approximately 2 cm above the lower esophageal sphincter (LES). Hydrochloric acid (0.1 N HCl, 50 mmol/L) with pepsin (3,200-4,500 U/mL), at pH 1.6, was then perfused into the esophagi of the experimental rats (n = 8) at 10 mL/hr continuously for 50 minutes. Normal saline solution (0.9% NaCl) was used in control rats (n = 6), and home cage control animals (n = 6) were given no stimulation. Thirty minutes after the perfusion, the rat was killed and the brain was removed and processed for c-Fos immunohistochemistry. A transverse section of the esophagus, 2 cm above the LES, was stained with hematoxylin and eosin stain for light microscopy. c-Fos immunoreactivity was significantly increased in a number of brain regions in the rats receiving the acid plus pepsin perfusion. These areas included the central amygdala, the Kölliker-Fuse nucleus, the nucleus of the solitary tract (NTS), the medial part of the NTS, the interstitial part of the NTS, the commissural part of the NTS, the paratrigeminal nucleus, the ambiguus nucleus, and the rostroventrolateral recticular nucleus. Perfusion with acid-pepsin solution also resulted in morphologic changes in the esophagus on light microscopy. This study suggests that acid plus pepsin perfusion of esophagus results in both neural activation in areas of the central nervous system and damage to the esophagus in an animal model.

Non-invasive estimation of liver fibrosis in non-alcoholic fatty liver disease using the 13 C-caffeine breath test.

Background and Aim:  Fibrotic progression in non‐alcoholic fatty liver disease (NAFLD) is associated with impaired hepatic function. The 13C‐caffeine breath test (CBT) is a non‐invasive, quantitative test of liver function. We sought to determine the utility of the CBT in detecting hepatic fibrosis in NAFLD.

Acute cisplatin nephrotoxicity in the rat

The earliest phase of cisplatin nephrotoxicity involves natriuresis due to impaired sodium reabsorption by the proximal tubule. To define the cell mechanism of this transport lesion, electron microprobe X-ray analysis was used to determine changes in the electrolyte composition of proximal tubule cells in kidneys taken from rats treated acutely with cisplatin (1 mg/100 g body weight). Compared to control animals injected with vehicle, cisplatin treated rats developed significant natriuresis, the fractional excretion of sodium rising over sevenfold. In kidneys removed 90 min following cisplatin, sodium concentration in proximal tubule cells was reduced by 4.2 mmol/kg wet weight, or 19%, compared to control values. When allowance was made for cell shrinkage in cisplatin-treated kidneys by deriving the cell content of sodium (mmol/kg dry weight), the reduction was even greater (28%). These data suggest that cisplatin reduces proximal tubule sodium reabsorption by inhibiting the entry of sodium into the cells across the apical membrane.