Frequent loss of copy number on the long arm of chromosome 21 in human esophageal squamous cell carcinoma

To understand the molecular pathogenesis of human esophageal cancer, we performed a comparative genomic hybridization (CGH) analysis using 10 esophageal squamous cell carcinomas. Frequent gains of 1q, 3q, 7p, 7q, 8q, 11q, and 20q and losses of 3p, 4p, 4q, 5q, 9p, 11p, 11q, 13q, 18q, 21q, and Y were observed. Among these regions, 21q has not yet been investigated in detail. We performed an allelotype study using 55 squamous cell carcinomas of the esophagus and 20 microsatellite markers on 21q and found LOH in 36 cases (65%): 22 (61%) of 36 cases with LOH indicated allelic loss in all informative loci, suggesting loss of the whole chromosome arm 21q, and five smallest regions of overlap were found. Our present results suggest the existence of a tumor suppressor gene(s) that plays a role in the genesis of squamous cell carcinoma of the esophagus.

Effects of Nd:YAG laser irradiation on morphometry and lung function in elastase-induced emphysema in rats

BACKGROUND & OBJECTIVE

Although thoracoscopic laser ablation therapy has been hailed as an effective surgical treatment for diffuse emphysema, no one has as yet made an in-depth study of the efficacy of this treatment. This investigation was undertaken to research the effects of laser pneumoplasty on an animal model of emphysema.

STUDY DESIGN/MATERIALS AND METHODS

Eight weeks after elastase treatment, the rats' left lungs were irradiated using contact Nd:YAG laser. Pulmonary function tests were performed 4 weeks after irradiation and the lungs were prepared for histologic examination.

RESULTS

Dense fibrous scars beneath the pleura were observed at 4 weeks after irradiation. Although mean linear intercept values of irradiated lungs were not much lower than those in the non-irradiated elastase-treated group, laser irradiation caused a significant decrease in lung volume. While there was no significant difference in quasistatic compliance, elastic recoil pressure of the lung increased to control levels at total lung capacity volume.

CONCLUSION

We conclude that laser therapy does not cause normalization of compliance, or improvement in the deeper part of the emphysematous lung, but rather a peripheral volume reduction and "encasement effect" on the lungs as a result of fibrotic scars.

[Clinical efficacy of low-dose weekly docetaxel combined with oral 5'-deoxy-5-fluorouridine (5'-DFUR) in advanced or metastatic breast cancer: a pilot trial]

Docetaxel (TXT) has been shown to be an up-regulator of human pyrimidine nucleoside phosphorylase (PyNPase) in tumors. We have tried to use the combination of low-dose weekly TXT with 5'-DFUR (LD + D) in patients with advanced or metastatic breast cancer. In this study, we compared the clinical efficacy of LD + D with that of conventional full-dose TXT (FD) and that of low-dose weekly TXT (LD). Twenty-one patients received 3 or 4 cycles of FD 60 mg/m2 every 3 or 4 weeks (group I), 14 patients received 8 cycles of LD 20-30 mg/m2 every week (group II) and 25 patients received 8 cycles of LD 20-30 mg/m2 weekly with oral 5'-DFUR 600-1,200 mg per day (group III). The overall response rates of groups I, II and III were 29%, 29% and 52% (p = 0.24), respectively. Grade 3-4 neutropenia was observed in 91% of group I, 6% of group II and 3% of group III. Nausea was present in 27% of group I, 28% of group II and 40% of group III. Higher incidence of gastrointestinal symptoms was found in LD + D, but the symptoms abated when the doses of 5'-DFUR were reduced. Low-dose weekly TXT with oral 5'-DFUR produced a higher response rate, but less hematologic toxicity than full-dose TXT, suggesting that this combination therapy is clinically useful and may be effective for patients with advanced or metastatic breast cancer.

Primary hepatic carcinoid tumor: a case report

A case of primary hepatic carcinoid tumor is reported. A 57-year-old woman had no endocrine symptoms. Light microscopic findings revealed tumor cells forming trabecular or insular structures and demonstrating diffuse positive staining by the Grimelius method. Mucin stained with Periodic acid-Schiff (PAS) and alcian-blue was partially present in the tumor cells. Immunohistochemically, most tumor cells stained positive with chromogranin A and cytokeratin stains. Intensive and careful investigation before and after the operation revealed no other origin of the tumor. We present this rare case, describe the clinical features of hepatic carcinoid, and discuss its diagnosis.

17 beta-Hydroxysteroid dehydrogenase type 1 and type 2 in ductal carcinoma in situ and intraductal proliferative lesions of the human breast

17 beta-hydroxysteroid dehydrogenases (17 beta-HSDs) are involved in the interconversion of biologically active and inactive sex steroids and are considered to play important roles in the in situ metabolism of estrogen in various estrogen dependent tissues. 17 beta-HSD type 1 catalyzes primarily the reduction of estrone (E1) to estradiol (E2), whereas 17 beta-HSD type 2 catalyzes primarily the oxidation of E2 to E1. However, the possible biological roles of these estrogen metabolizing isozymes in human breast cancer, especially in carcinogenesis of the human breast, have not been examined in detail. Because of the potential roles of estrogens in the early stages of human breast carcinogenesis, we have examined the immunolocalization of 17 beta-HSD type 1 and type 2 isozymes and estrogen receptor alpha(ER alpha) in both normal human breast tissue and in breast cancers, including ductal carcinoma in situ (DCIS), proliferative disease without atypia (PDWA) or fibrocystic disease and atypical ductal hyperplasia (ADH). We also correlated these findings with clinicopathological findings, Ki67 antigen, progesterone receptor (PR), c-erbB-2, and p53. 17 beta-HSD type 2 immunoreactivity was sporadically detected in non-proliferative or Ki67 negative ductal epithelia of normal breast, but rarely in breast carcinoma cells. 17 beta-HSD type 1 immunoreactivity was detected in 12/22 (54.5%) PDWA cases, 8/26 (30.8%) ADH cases, and 25/40 (62.5%) DCIS cases, respectively. 17 beta-HSD type 1 immunoreactivity was not statistically correlated with the age of the patients, Ki67 labeling index (LI), and PR LI, p-53 and c-erbB-2 immunoreactivity. There was no significant correlation between ER alpha LI and 17 beta-HSD type 1 immunoreactivity. There was a positive correlation between ER alpha and Ki67 LI in PDWA, whereas a negative correlation was detected between ER alpha and Ki67 LI in DCIS. There was no correlation between ER alpha and Ki67 LI in ADH. These results suggest that in human breast epithelial cells, development of ADH and DCIS may be associated with the loss and/or deviation of oestrogen dependent regulation of cell proliferation.

Correlation of three-dimensional magnetic resonance imaging with precise histopathological map concerning carcinoma extension in the breast

This study was initiated to clarify the ability of magnetic resonance imaging (MRI) in defining breast carcinoma extension by comparing MRI to detailed histopathological analysis. Mastectomy (n = 14) or quadrantectomy (n = 44) specimens were sub-serially sectioned and mapped in detail in 58 breast cancer patients. Morphologically, we classified the lesions utilizing MRI into three patterns in relation to their histology. Numerically, we assessed the maximum distance of carcinoma extension using MRI, mammography, and ultrasonography (US). Linear regression was calculated for each of the three imaging measurements versus histopathological measurements. Three imaging patterns were observed by MRI, (1) localized (n = 30), (2) segmentally extended (n = 19), and (3) irregularly extended (n = 5). The localized pattern showed a distinct focal mass, but in 10 cases, microscopic ductal carcinoma in situ (DCIS), or invasive lobular carcinoma, which were not depicted by MRI, existed. The segmentally extended pattern showed diffuse enhancement along duct-lobular segments, forming a 'cone' shape. Histologically, pure (n = 4) or predominant (n = 10) DCIS was distributed segmentally. The irregularly extended pattern showed thick branches extending out from the index tumor which were histologically revealed to be stromal invasion of ductal carcinoma. From the results of linear regressions, MRI was the most accurate modality in histologically measuring the extent of the cancer. When cases were limited to patients who were classified into segmentally or irregularly extended pattern by MRI (n = 24), MRI was more accurate than mammography and US, even if they were combined (P < 0.05). MRI may provide additional information concerning carcinoma extension prior to surgery, especially in patients classified into 'extended patterns' by MRI.

LOH analyses of premalignant and malignant lesions of human breast: frequent LOH in 8p, 16q, and 17q in atypical ductal hyperplasia

The number of breast cancer patients is increasing yearly, and it is important to establish effective methods for clinical management. We investigated loss of heterozygosity (LOH) in tumors derived from 23 patients that harbored synchronous lesions of atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS), and invasive ductal carcinoma (IDC). Fourteen selected microsatellite markers that were mapped to and/or very close to the tumor suppressor genes or regions with frequent LOH in breast cancer. Our results suggested that i) losses of chromosomal regions 8p, 16q, and 17q are early genetic changes, and ii) ADH is a premalignant lesion for the development of breast cancer.

Probiotic bacteria stimulate gut epithelial cell proliferation in rat

Probiotics are used for various intestinal diseases. However, their effects on gut epithelial cell proliferation have not been investigated. We administered 10(7) colony-forming units of Lactobacillus casei or Clostridium butyricum, or no probiotics (control) by gastric intubation once a day for seven days to rats fed an elemental diet. We estimated the crypt cell production rate of the jejunum, ileum, cecum, and distal colon. We also quantified cecal bacteria. Both probiotics increased the crypt cell production rate of the jejunum and ileum by 25-40%, of the cecum by 70%, and of the distal colon by more than 200% compared with control. Only minor variance in the cecal bacterial composition existed among the three groups. Probiotics enhanced gut epithelial cell proliferation in rats fed an elemental diet.

Correlation of unilateral thoracoscopic lung volume reduction with improvement in lung function and exercise performance in patients with severe pulmonary emphysema

This study was conducted to investigate the correlation of thoracoscopic lung volume reduction to changes in pulmonary function and exercise performance in patients with pulmonary emphysema. Unilateral thoracoscopic lung volume reduction treatment was performed in 30 patients with severe pulmonary emphysema. If large bullae were present, they were excised using an endoscopic stapling device, and the emphysematous pleura was contracted by neodymium:yttrium-aluminium-garnet laser to reduce the volume of nonfunctional lung air space. Pulmonary function and incremental exercise tests were performed before and at least 3 months after treatment. Follow-up functional evaluation showed a highly significant improvement in the forced expiratory volume in 1s (FEV1), forced vital capacity, static compliance, and maximal oxygen uptake. The functional residual capacity as measured by the gas dilution method (FRCgas), was unchanged; however, it was found to be decreased significantly when measured by body plethysmograph (FRCbox). Positive correlations existed between the reduction in FRCbox and the increase in FEV1 (r = 0.586, P = 0.0042) and maximal oxygen uptake (r = 0.550, P = 0.018). Pulmonary ventilation and exercise ability in patients with pulmonary emphysema were improved in a volume-dependent manner by thoracoscopic lung volume reduction. These findings indicate that patients with a preoperative trapped gas volume level exceeding 11 would be ideal candidates for thoracoscopic lung volume reduction.

Identification of a 5-cM region of common allelic loss on 8p12-p21 in human breast cancer and genomic analysis of the hEXT1L/EXTR1/EXTL3 gene in this locus

The short arm of chromosome 8 is frequently lost in many human carcinomas including breast cancer, suggesting the presence of a tumor suppressor gene(s) in this region. We identified a gene termed hEXT1L/EXTR1/EXTL3 (hEXT1L hereinafter) that was mapped to chromosome bands 8p12-p21 where frequent LOHs of this region was reported in breast cancer. The existence of the third breast cancer susceptibility gene was also suggested in this region by linkage analysis. We further performed LOH analysis in 8p12-p21 in 34 breast cancers and identified a 5-cM region of common allelic loss that overlapped with the locus for positive lod score in familial breast cancer. We further analyzed genomic alterations of hEXT1L in tumors in which frequent LOHs of 8p were reported. A total of 327 cancers (313 primary tumors and 14 cancer cell lines) including 22 primary breast cancers were analyzed, but none of the tumors had somatic mutations: only one thyroid cancer patient without any family history of cancer had a 9-bp insertion in the constitutional DNA. These results suggest that mutations of hEXT1L do not play a major role in the development of sporadic cancers including breast cancer, and that other tumor suppressor gene(s) exists in the 5-cM region identified in this study.

[Effects of low dose pimobendan in patients with cor-pulmonale]

The acute and chronic efficacy of low dose pimobendan (1.25 mg x 2/day) was evluated in patients with cor-pulmonale. Fifteen patients (12 men, 3 women, mean age 73 +/- 5 yr) with right ventricular dysfunction judged by Tei's Doppler index (> or = 0.4) and poor working capacity (exercise tolerance: 2.2-6.6 MET) were studied. Mean pulmonary artery pressure, cardiac output, total pulmonary resistance using Swan-Ganz catheter, and arterial oxygen and carbon dioxide pressure (PaO2, PaCO2) were measured before and 24 hr after pimobendan administration. Maximal oxygen intake (MET), saturation of arterial blood oxygen at rest and desaturation by treadmill stress test were measured before and 1 month after pimobendan administration. Pulmonary artery pressure decreased (17.6 +/- 4.7 to 10.2 +/- 2.3 mmHg, p < 0.001) and cardiac output increased (3.5 +/- 0.6 to 5.1 +/- 0.9 l/min, p < 0.001), resulting in decreased total pulmonary resistance (5.0 +/- 1.3 to 2.1 +/- 0.7 U, p < 0.001), and a mild decrease in PaO2 (74 +/- 8 to 70 +/- 10 mmHg, p < 0.05). Exercise tolerance improved significantly (4.8 +/- 1.7 to 6.8 +/- 2.2 MET, p < 0.001), without deterioration of PaO2 and desaturation. These results indicate that low dose pimobendan is useful for the treatment of patients with cor-pulmonale.

Elimination of Kupffer cells and nafamostat mesilate rinse prevent reperfusion injury in liver grafts from agonal non-heart-beating donors

BACKGROUND

We hypothesized that microcirculatory disturbance was an obstacle to liver transplantation (LTx) from non-heart-beating donors (NHBDs) and that it was attributed mainly to a deterioration of sinusoidal endothelial cells (SECs) and sinusoidal narrowing. This study was designed to examine porcine orthotopic LTx using livers obtained from pretreated agonal NHBDs, and to determine whether the maintenance of the liver microcirculation would result in successful LTx from agonal NHBDs.

METHODS

Pigs were allocated to five groups: (i) control group; (ii) NM group, in which grafts were rinsed with nafamostat mesilate (NM) rinse; (iii) LD group, in which Kupffer cells in grafts were eliminated by liposome-encapsulated dichloromethylene diphosphonate (L-DMDP); (iv) LDNM group, in which grafts pretreated with L-DMDP were rinsed with NM rinse; (v) heart-beating donor (HBD) group. In all groups, but the HBD group, the livers were pretreated with FK506 and prostaglandin I2 analogue, and were preserved in University of Wisconsin solution after cardiac arrest. Thereafter orthotopic LTx was performed.

RESULTS

After reperfusion, it was histologically demonstrated that elimination of Kupffer cells prevented SECs deterioration and NM rinse prevented sinusoidal narrowing. The hepatic energy charge recovered in all groups except the control group. In the LDNM group, three of four recipients survived more than 7 days.

CONCLUSIONS

For a successful LTx from agonal NHBDs, it is important to prevent microcirculatory disturbance caused by SEC deterioration and sinusoidal narrowing after reperfusion. Combination therapy consisting in the elimination of Kupffer cells and NM rinse prevented primary graft non-function in liver grafts from agonal NHBDs.

A case control study on the effectiveness of breast cancer screening by clinical breast examination in Japan

A case-control study was conducted in Miyagi and Gunma prefectures, Japan, to evaluate the effectiveness of breast cancer screening by clinical breast examination (CBE) alone in reducing breast cancer mortality. Case subjects, who were female and had died of breast cancer, were collected from residential registry files and medical records. Control subjects matched in sex, age and residence were randomly selected from residential registry files. The screening histories during 5 years prior to the cases having been diagnosed as breast cancer were surveyed using the examinee files of the screening facilities. Finally, the data of 93 cases and 375 controls were analyzed. The odds ratio (OR) of breast cancer death for participating in screening at least once during 5 years was 0.93 (95% confidence interval (95% CI) 0.48-1.79). The cases were more symptomatic than the controls when screened. If the participants who had had symptoms in their breasts were classified as not screened, the OR decreased to 0.56 (95% CI 0.27-1.18). The case control study suggests that the current screening modality (CBE) lacks effectiveness (OR = 0.93), although it might be effective for an asymptomatic population (OR = 0.56). The number of cases was small, and a larger case-control study is desirable to define whether CBE is effective or not. However, it is necessary to consider the introduction of mammographic screening to reduce breast cancer mortality in Japan.

Risk of breast cancer in Japanese women with benign breast disease

To investigate the risk of breast cancer development in women with benign breast disease (BBD), 387 screen-detected BBD women and 1,489 normal women, taken from participants in the breast cancer screening program during 1978-1986, were followed through 1991. While 2,811 person-years in the BBD group and 11,018 person-years in the normal group were accumulated, 5 women in the BBD group and 6 women in the normal group developed breast cancer. Using the Mantel-Haenszel method, relative risks (RR) were estimated for all women with BBD and women in some BBD types. Significantly elevated risk of breast cancer was observed in all women with BBD (RR = 3.26, 95% confidence interval (CI) 1.08-9.83). Women with proliferative BBD were at high risk of breast cancer (RR = 8.48, 95% CI 2.99-24.10), but no increased risk was observed for women with non-proliferative BBD (RR = 0.93, 95% CI 0.11-7.66). These results are consistent with those in high-risk countries for breast cancer. In the management of women with BBD, histopathological diagnosis of the breast lesion is essential and women with proliferative BBD should be followed up carefully.

Cell cycle inhibitory protein p27 in esophageal squamous cell carcinoma

BACKGROUND

p27 protein is one of the cdk inhibitors which regulates the progression from G1 to S phase of the cell cycle. Reduced expression of p27 protein has been reported to be correlated with poor clinical outcome in patients with various cancers.

MATERIALS AND METHODS

We performed immunohistochemistry of both p27 and Ki67 in 136 cases of resected human esophageal squamous cell carcinoma, and evaluated the association between p27 immunoreactivity and clinicopathological features including clinical outcome in these patients. We also examined the correlation between labeling index or the percentage of positive tumor cells for p27 and Ki67 in serial tissue sections in these cases.

RESULTS

Cases with invasion of the muscularis propria or adventitia had significantly (p < 0.05) higher p27 LI (65.0 +/- 23.7) than those with invasion limited to mucosa or submucosa and those with carcinoma in situ (58.9 +/- 18.3). There were no significant correlations between p27 and other clinicopathological factors such as sex, age, tumor size, differentiation type, nodal status and histological stage. The cases with p27 LI below 40% tended to have a worse prognosis than those with p27 LI above 40%. There was no significant correlation between Ki67 and p27 LIs.

CONCLUSIONS

Reduced expression of p27 may be correlated with the biological behavior of esophageal squamous cell carcinoma and may play an important role in the early stages of cancer.

Topoisomerase II alpha expression in esophageal squamous cell carcinoma

BACKGROUND

DNA topoisomerase II alpha (topo II alpha) is associated with active cell proliferation of mammalian cells. Topo II alpha overexpression has been reported in a number of human malignancies and is considered to be related to their biological behaviors.

MATERIALS AND METHODS

We examined the expression of topo II alpha immunohistochemically in 136 cases of human esophageal squamous cell carcinoma, 10 foci of squamous dysplasia and 10 non-pathologic squamous epithelium. We calculated the labeling index (LI) or the percentage of immunopositive cells for Topo II alpha and Ki67, and Topo II alpha LI/Ki67 LI (T/K ratio). These findings were then correlated with clinicopathological features of the patients including their clinical outcome.

RESULTS

Both topo II alpha and Ki67 immunoreactivity were detected in the nuclei. A significant positive correlation was obtained between Topo II alpha and Ki67 LIs in all the specimens examined. Topo II alpha LI and T/K ratio were 24.5 +/- 8.0% and 1.04 +/- 0.64 for carcinoma, 19.1 +/- 15.2% and 0.68 +/- 0.29 for dysplasia and 14.0 +/- 14.1% and 0.55 +/- 0.17 for non-pathologic epithelium, respectively. Topo II alpha LI and T/K ratio in carcinoma cases were significantly higher than those of normal epithelium. Topo II alpha LI alone did not correlate with any of clinicopathological parameters examined but among carcinoma cases, cases with lymph nodes metastasis or higher histological stages had significantly higher T/K ratio than those without lymph node metastasis or lower histological stages. In addition, carcinoma cases with T/K ratio of greater than 0.8 demonstrated significantly worse prognosis than those with T/K ratio of smaller than 0.8.

CONCLUSIONS

The relative overexpression of topo II alpha as compared with Ki67, i.e., increased T/K ratio was detected in esophageal squamous cell carcinoma and is considered to represent a dysregulation or qualitative alteration in topo II alpha, possibly associated with malignances, as reported in other human cancers. In addition, topo II alpha overexpression may also be correlated with the aggressive biological behavior of the patients with esophageal squamous cell carcinoma.

Fragility of the electron transport chain and superoxide generation in mitochondria of the liver graft after cold ischemia

BACKGROUND

After cold ischemia, electrons transferred in the electron transport chain may leak out of the mitochondria in proportion to the deterioration of mitochondrial oxidative phosphorylation. This seems to be one major cause of the lipid peroxidation that occurs mainly in the hepatocytes at reperfusion in liver transplantation. To examine this hypothesis, we investigated superoxide generation and the amount of oxidative phosphorylation in the mitochondria isolated from rat livers after cold preservation.

METHODS

Rat liver was preserved in University of Wisconsin solution at 4 degrees C for 24 hr. The mitochondrial fraction was prepared, and the amount of ATP synthesis and superoxide generation was investigated. Superoxide generation in the electron transport chain of submitochondrial particles was also measured by a chemiluminescence recorder.

RESULTS

The amount of ATP synthesis was significantly decreased after 12 hr of cold preservation. In the whole mitochondria, superoxide production in the presence of succinate was approximately 1/2000 to 1/3000 less than that observed in the submitochondrial particles at any determination point, and superoxide production was not affected by cold preservation. In the presence of antimycin A, superoxide production in the mitochondria after 18 hr of preservation increased significantly.

CONCLUSION

These results indicate that the electron transfer in the complex III of the mitochondrial membrane becomes leaky after long periods of cold ischemia, but that leakage of superoxide anion did not increase, although the mitochondrial respiratory phosphorylation was deteriorated. We conclude that superoxide through the mitochondrial membrane cannot cause lipid peroxidation in hepatocytes at reperfusion even after a long period of cold ischemia.

Aromatase and sex steroid receptors in human vena cava

Among sex steroids, especially estrogen metabolism has been considered to play a role in the function and pathology of human veins. We investigated the expression and activity of the estrogen-producing enzyme aromatase and estrogen receptor (ER) in human vena cava to assess possible in situ biosynthesis of estrogens and their modes of action. We first examined aromatase expression by immunohistochemistry in human inferior vena cava obtained from 29 autopsy cases (11 males, 18 females, 63.6 +/- 3.0 years old). We then semiquantitated the level of aromatase mRNA by reverse transcriptase-polymerase chain reaction in 24 cases and aromatase activity by 3H-water assay in 15 cases to examine whether or not and in which cell types aromatase was expressed. We also studied alternative use of multiple exon 1s of its gene and immunolocalization of 17beta-hydroxysteroid dehydrogenase type I (17beta-HSD I), which converts estrone produced by aromatase to estradiol, a biologically active estrogen and ER. Aromatase and 17beta-HSD I immunoreactivity were both detected in smooth muscle cells (SMC) of the media in all the cases and in endothelial cells (EC) in 20 and 22 cases, respectively. ER immunoreactivity was detected in SMC of vena cava in 21 cases. The amount of aromatase mRNA was significantly greater in the cases utilizing 1c (I.3) or 1d (P.II) of exon 1 (9 cases, 191.1 +/- 26.3 attomol/ng total RNA) than those utilizing 1b (I.4) as the promoter (14 cases, 50.6 +/- 13.0 attomol/ng total RNA) (p < 0.01). Significant correlation (p < 0.05) was observed between the amount of aromatase mRNA and aromatase activity in 15 cases examined. No significant correlation was detected between the amount of aromatase mRNA or aromatase labeling index and the ER status. These results suggest that estrone and estradiol are produced in the human vena cava and that their production is mediated by aromatase and 17beta-HSD I, respectively but not all of these locally synthesized estrogens may not work directly in situ.

The mechanism of injury in a steatotic liver graft during cold preservation

BACKGROUND

Fatty livers are more prone to primary nonfunction after transplantation. It is known that cell injury is strongly associated with alterations in the content and composition of membrane lipids. We assumed that plasma membrane (PM) fluidity, which is the most important property of the membrane, differed between fatty and normal livers.

METHODS

The livers from obese and lean Zucker rats were flushed with cold Ringer's lactate and University of Wisconsin (UW) solution via the portal vein and preserved in cold UW solution for 24 hr. Histological examinations of electron microscopy were performed to investigate of sinusoidal lining cells (SLCs). PMs were isolated using a discontinuous density gradient of Percoll, and the lipid compositions were determined by chromatography.

RESULTS

SLCs of fatty livers were markedly injured compared with control livers even after short preservation time. Moreover, many blebs were observed in the obese rats even after short preservation time. As for PM lipid composition, the cholesterol/phospholipid (PL) ratio of total PM was 0.14+/-0.03 in the obese rats and 0.21+/-0.03 in the lean rats (P<0.05). The relative proportions of polyunsaturated fatty acids among PLs in PM were 35.7+/-1.2% vs. 45.9+/-1.5% (P<0.0001). These results indicated that the fluidity of the PM in the obese rats is decreased after exposure to low temperatures.

CONCLUSIONS

Our results suggest that steatotic livers from obese donors are more susceptible to cold preservation injury than livers without steatosis because of the severe deterioration of SLCs, and it is associated with PM fluidity even after short-term cold preservation.