Graft replacement of transverse aortic arch using the arch vessels first technique

In surgical treatment of aortic arch aneurysm or aortic dissection, we have been employing retrograde cerebral perfusion (RCP). In the present study, we have developed "arch vessels first technique" to shorten perfusion time and achieved an excellent clinical outcome. The surgical procedure "arch vessels first technique" is outlined as follows. RCP is initiated following circulatory arrest, while a woven dacron graft (12 mm in diameter, the dacron graft must be prepared in advance) with two side arms (12 mm in diameter, i.e., with the same diameter) is anastomosed left subclavian artery, left common carotid artery and right brachiocepharic artery in a sequential manner. Then, brain circulation is initiated via one end of the dacron graft. Subsequently, in patients with aortic dissection, a 26 mm woven dacron tubular prosthesis is inserted, using an elephant trunk procedure, to perform "distal anastomose". A partial clamp is applied to the 12 mm woven dacron graft mentioned above, while this 26 mm graft is anastmosed to the 12 mm woven dacron graft side to side, thus reinitiating systemic circulation. While rewarming, the 26 mm woven dacron tubular prosthesis is proximal anastomosed. Mean RCP time was 79.4 minutes, using the conventional procedure "aortic arch distal anastomose", whereas the RCP time was shortened by this procedure "arch vessels first technique", as evidenced by mean RCP time of 57 minutes for patient with aortic dissection and of 39 minutes for patient with saccular aneurysm.     

The effect of androgen on the retention of extinction memory after conditioned taste aversion in mice

Conditioned taste aversion (CTA) induced by the application of a novel taste such as sodium saccharin (Sac) as the conditioned stimulus (CS) and a malaise-inducing agent as the unconditioned stimulus (US), results in acquisition of CTA memory to Sac. In contrast, CTA is extinguished by repeated presentations of the CS without the US, resulting in acquisition of the extinction memory. We examined the effects of androgenic hormones on acquisition and retention of extinction memory in mice. We gonadectomized sexually immature mice and continuously administered androgens to these animals. After sexual maturation, the mice underwent a conditioning period followed by an extinction period. Retrieval tests revealed that the androgen-treated group showed significantly greater retention of extinction memory than the non-treated group 5 weeks later, whereas such significant difference was not observed in acquisition of extinction memory. These results demonstrate the enhancing effect of androgens on retention of extinction memory.     

Spontaneous amphophilic focus in the liver of a young Sprague-Dawley rat

Altered hepatocellular focus was histopathologically observed in the liver of a 6-week-old Sprague-Dawley rat. The hepatocytes within this lesion had diffusely eosinophilic cytoplasm with scattered basophilia and slightly enlarged nuclei with prominent nucleoli. Based on these cytological characteristics, the lesion of these hepatocytes was classified as an amphophilic focus. This is the first report to describe spontaneous amphophilic focus in a young rat.     

Diet modification and its influence on metabolic and related pathological alterations in the SHR/NDmcr-cp rat,an animal model of the metabolic syndrome

SHR/NDmcr-cp (SHR/NDcp) rats, which carry a nonsense mutation of the leptin receptor gene, are known to spontaneously develop hypertension, obesity and hyperlipidemia, and have therefore found use as an animal model of the metabolic syndrome and type 2 diabetes. However, some recent studies on SHR/NDcp rats revealed only mild elevation of blood glucose levels. To investigate whether metabolic factors including blood glucose and histopathological alterations of SHR/NDcp rats deteriorate with a diabetogenic diet, biochemical and histopathological examinations were conducted with animals fed normal or diabetogenic diets for 20 weeks. SHR/NDcp rats receiving the normal diet displayed obesity, hypertension, hyperlipidemia, and mild elevation of blood glucose and HbA1c levels. Urinary glucose excretion was noted in only 1 out of 6 animals. Histologically, macro- and micro-vesicular steatosis in the liver, glomerular and tubular damages in the kidney and islet hyperplasia mainly of beta cells in the pancreas were characteristically noted. In SHR/NDcp rats fed the diabetogenic diet, obesity was more severe, with higher blood glucose and HbA1c levels, increased numbers of animals with urinary glucose excretion, and more pronounced hepatic steatosis and renal tubular changes. However, elevation of blood glucose levels and urinary glucose excretion proved transient. These observations indicate that the diabetic state and associated histopathological alterations in SHR/NDcp rats are exacerbated by feeding a diabetogenic diet, but the effects are limited. Elevated islet function with compensative insulin secretion might be related to amelioration of the hyperglycemic state. Further diet modification could be needed to induce a more prominent and persistent diabetic state in SHR/NDcp rats.