Functional and Morphological Characteristics of Pancreatic Islet Lesions Induced by Quinolone Antimicrobial Agent Gatifloxacin in Rats.

We characterized pancreatic islet lesions induced by several quinolones using functional and morphological examinations of the pancreatic islets in male rats orally administered gatifloxacin, lomefloxacin, or levofloxacin at 300 mg/kg for 14 consecutive days. Consequently, in contrast to lomefloxacin or levofloxacin, gatifloxacin increased serum glucose and glycosylated albumin on day 14 and elevated serum glucose tended to decrease insulin in the intravenous glucose tolerance test. Microscopically, only gatifloxacin induced cytoplasmic vacuoles containing eosinophilic homogenous contents in islet cells. Immunohistochemical examination revealed that vacuolated islet cells were positively stained for insulin, demonstrating they were pancreatic ß cells. Electron microscopy showed that the cytoplasmic vacuoles represented dilated cisterna of the rough endoplasmic reticulum filled with electron-lucent materials in pancreatic ß cells. Moreover, insulin secretory granules were drastically decreased in vacuolated islet cells, suggesting impaired insulin synthesis and/or transport. This gatifloxacin-induced pancreatic toxicity in rats was considered to be associated with high pancreatic drug distribution. These results demonstrated that gatifloxacin provoked functional and morphological pancreatic ß cell alteration associated with impaired insulin synthesis and/or transport, leading to hyperglycemia.

Plasma citrulline is a sensitive safety biomarker for small intestinal injury in rats.

Plasma citrulline is decreased in cases of severe intestinal injury with apparent villus and cellular atrophy. However, the fluctuation of plasma citrulline in slight intestinal injury remains to be investigated. To clarify this, irinotecan at 30 mg/kg or 60 mg/kg was administered intravenously to rats. Irinotecan reduced plasma citrulline concentrations compared to those in the pair-fed control, being concurrent with slight single cell necrosis and mucosal epithelium regeneration in the small intestine without apparent villus and cellular atrophy. Gene expression of enzymes converting glutamine to citrulline was decreased in the small intestine of the injury model. Moreover, citrulline and arginine levels in the ileum were decreased without alterations to glutamine and glutamate levels, indicating that citrulline synthesis from glutamine was impaired. Metabolome analysis revealed that plasma citrulline and arginine levels were decreased, while there were no marked alterations in other amino acids, metabolites of glycolysis, ketone bodies, or fatty acids. These results suggested that a decreased plasma citrulline level was unlikely to result from amino acid catabolism in response to malnutrition. In conclusion, plasma citrulline concentration reflects slight intestinal injury without apparent villus and cellular atrophy, and thus, it would be a sensitive biomarker for the small intestinal injury.

Optimum conditions for detecting hepatic micronuclei caused by numerical chromosome aberration inducers in mice.

To ascertain an optimum condition for detecting micronuclei in the liver caused by numerical aberration inducers, either carbendazim (125-1000mg/kg, p.o.), colchicine (0.375-1.5mg/kg, i.v.), cytochalasin B (2.5-20mg/kg, i.v.), diazepam (3.13-25mg/kg, i.v.), noscapine (7.8-62.5mg/kg, i.v.), paclitaxel (1-100mg/kg, i.v.) or trichlorfon (18.75-150mg/kg, i.v.) was administered once to male Slc:ddY mice 1 day before or after partial hepatectomy (PH, Day 1). Five days after PH (on Day 6), hepatic micronuclei were determined in conjunction with classifications of the main nuclei and relative liver weights as a proliferative indicator or a dysfunction marker of cell division. Additionally, hepatocyte proliferation index (HPI) was calculated by using mono-, bi- and multinucleated cell counts. Treatment of mice with six compounds, except for colchicine, after PH showed higher incidence of micronucleated hepatocytes (MNH) than that before PH, and also increases in binucleated and multinucleated cells. Especially for carbendazim, diazepam, noscapine and trichlorfon, the dosing after PH was essential for the detecting numerical aberration. Colchicine evidently increased HPI and decreased relative liver weights without MNH induction on Day 6. On Day 8 when HPI and relative liver weights almost returned to the basal range, a significant increase in MNH was noted. This implied that the strong inhibition of colchicine on hepatocyte proliferation may obstruct the induction of MNH on Day 6. In conclusion, to detect the potential numerical aberration, exposure of mice to test chemicals should be performed 1 day after PH, during which enhanced proliferation of hepatocytes was seen, and it would be better to analyze the liver specimens on Day 6 or more post-PH.

Illness experiences of patients with ischemic heart disease during their transitional phase from hospitalization to discharge in Japan.

The purpose of this study was to explore the experience of patients with ischemic heart disease (IHD) during the transitional phase from hospitalization to discharge. Twenty-four patients who experienced IHD for the first time comprised the sample of the study. Semi-structured interviews were conducted during the transitional phase. The results of the qualitative inductive analysis showed two categories of illness experience: (i) the connection of heart attack experience with the self, and (ii) the instability of the self as a patient with heart disease. The participants were found to vacillate between the self as patient with a heart disease and the typical self before the disease onset. The transitional phase is the time when patients experience changes in their symptoms and physical conditions rather than a condition of stability signifying recovery. Patients are expected to manage the symptoms of their heart disease by themselves; however the participants showed signs and symptoms of confusion and anxiety about facilitating their own care. These findings suggest the importance of outpatient nursing practice focusing on the support and emphasis on nursing interventions for patient anxiety and alleviation of confusion through the management of symptoms of heart disease after discharge.

Different responses in mutagenesis induced by quinolone antibacterial agents in two Escherichia coli WP2uvrA/ pKM101 strains.

Escherichia coli WP2uvrA/pKM101 strain obtained from a different supplier had a lower response to quinolone antibacterial agents (quinolones) when compared to an ordinary responsive strain. The present study was designed to examine the mechanism of lower susceptibility of the new strain to quinolones. A reverse mutation assay showed the new strain was low responsive to six quinolones compared to a responsive strain, while there was no difference in sensitivity to antibacterial activity of quinolones or the mutagenic activity of the positive control compounds in both strains. The sequence of mucA and B genes, which involve chemical and ultraviolet (UV) -induced mutagenesis through error-prone repair, and the total length of plasmid pKM101 in both strains were identical. Furthermore, transformed WP2uvrA/pKM101 strains, which were made by separately electroporating pKM101 extracted from these two strains into WP2uvrA, showed almost the same responses to the mugatenic- and antibacterial- activity of quinolones as the original responsive strain. The two original strains and the recipient WP2uvrA were proven to have proper genetic characteristics. It was demonstrated that the lower susceptibility of the new WP2uvrA/pKM101 strain to the mutagenesis of quinolones was not due to any changes in either plasmid pKM101 or the characteristics of the host detected by a routine check (tryptophan requirements, sensitivity to UV light and cell membrane permeability) of their genetic characteristics.

Early pathophysiological features in canine renal papillary necrosis induced by nefiracetam.

To ascertain the early pathophysiological features in canine renal papillary necrosis (RPN) caused by the neurotransmission enhancer nefiracetam, male beagle dogs were orally administered nefiracetam at 300 mg/kg/day for 4 to 7 weeks in comparison with ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), at 50 mg/kg/day for 5 weeks. During the dosing period, the animals were periodically subjected to laboratory tests, light-microscopic, immunohistochemical, and electron-microscopic examinations and/or cyclooxygenase (COX)-2 mRNA analysis. In laboratory tests, a decrease in urinary osmotic pressure and increases in urine volume and urinary lactate dehydrogenase (LDH) level were early biomarkers for detecting RPN. Light-microscopically, nefiracetam revealed epithelial swelling and degeneration in the papillary ducts in week 7, while ibuprofen displayed degeneration and necrosis in the papillary interstitium in week 5. In immunohistochemical staining with COX-2 antibody, nefiracetam elicited a positive reaction within interstitial cells around the affected epithelial cells in the papillary ducts (upper papilla) in week 7, and ibuprofen positively reacted within interstitial cells adjacent to the degenerative and/or necrotic lesions in week 5. Ultrastructurally, nefiracetam exhibited reductions of intracellular interdigitation and infoldings of epithelial cells in the papillary ducts, whereas ibuprofen showed no changes in the identical portions. Thus, the early morphological change in the papilla brought about by nefiracetam was quite different from that elicited by ibuprofen. By the renal papillary COX-2 mRNA expression analysis, nefiracetam exceedingly decreased its expression in week 4, but markedly increased it in week 7, suggesting an induction of COX-2 mRNA by renal papillary lesions. These results demonstrate that the epithelial cell in the papillary ducts is the primary target site for the onset of RPN evoked by nefiracetam.