Cryopreserved allografts versus end-to-end anastomosis for the reconstruction of a segment-resected portomesenteric vein during advanced pancreatic cancer surgery.

BACKGROUND: Porto-mesenteric vein (PMV) infiltration of pancreatic cancer is classified as borderline resectable cancer. For en-bloc resectability, the probability of PMV resection and reconstruction is the most decisive factor. The purpose of this study was to compare and analyze PMV resection and reconstruction during pancreatic cancer surgery using end-to-end anastomosis (EA) and a cryopreserved allograft (AG) and to verify the effectiveness of reconstruction using an AG. METHODS: Between May 2012 and June 2021, 84 patients (65 underwent EA, and 19 received AG reconstruction) underwent pancreatic cancer surgery with PMV reconstruction. An AG is a cadaveric graft with a diameter of 8-12 mm and is obtained from a liver transplant donor. Patency after reconstruction, disease recurrence, overall survival, and perioperative factors were assessed. RESULTS: The median age was higher in EA patients (p = .022) and neoadjuvant therapy (p = .02) was more in AG patients. Upon histopathological examination, the R0 resection margin did not show a significant difference by reconstruction method. During a 36-month survival analysis, primary patency was significantly superior in EA patients (p = .004), and there was no significant difference in recurrence-free survival (p = .628) or overall survival (p = .638) rates. CONCLUSION: Compared with EA, AG reconstruction after PMV resection during pancreatic cancer surgery showed a lower primary patency, but there was no difference in recurrence-free or overall survival rates. Therefore, the use of AG can be a viable option for borderline resectable pancreatic cancer surgery if the patient is properly followed-up postoperatively.

Fluorescence cholangiography for detection of a cystic duct drained into an accessory hepatic duct: A case report.

INTRODUCTION: Laparoscopic cholecystectomy is a safe and standard procedure, but serious bile duct injury may occur due to anatomical anomalies of the biliary tract, especially the accessory hepatic duct. The use of intraoperative fluorescence cholangiography with indocyanine green during laparoscopic cholecystectomy can reportedly prevent bile duct injury. PRESENTATION OF CASE: A 55-year-old woman with upper abdominal pain was referred to our hospital. Laboratory investigations revealed elevated leukocytes and biliary enzymes, while computed tomography demonstrated increased fatty tissue density around the gallbladder. Magnetic resonance cholangiopancreatography and drip infusion cholangiographic-computed tomography showed that the cystic duct drained into an accessory hepatic duct. Due to the diagnosis of cholelithiasis with a biliary anomaly, we performed laparoscopic cholecystectomy using fluorescence cholangiography with indocyanine green. We were able to recognize the accessory hepatic duct and cystic duct, then safely dissect the cystic duct without bile duct injury. DISCUSSION: Laparoscopic cholecystectomy is generally regarded as a safe procedure, but complications and even mortalities can arise in patients with anatomical anomalies of the biliary tract. The aid of intraoperative fluorescence cholangiography with indocyanine green allowed to recognize and identify the accessory hepatic duct and cystic duct, allowing us to operate without injury to the bile duct. CONCLUSIONS: Our experience supports the ease of use, safety, and effectivity of fluorescence cholangiography with indocyanine green. This may become the optimal standard technique to prevent bile duct injury.

Intensive endoscopic resection for downstaging of polyp burden in patients with familial adenomatous polyposis (J-FAPP Study III): a multicenter prospective interventional study.

BACKGROUND: Total colectomy is the standard treatment for familial adenomatous polyposis (FAP). Recently, an increasing number of young patients with FAP have requested the postponement of surgery or have refused to undergo surgery. We aimed to evaluate the effectiveness of intensive endoscopic removal for downstaging of polyp burden (IDP) in FAP. METHOD: A single-arm intervention study was conducted at 22 facilities. Participants were patients with FAP, aged ≥ 16 years, who had not undergone colectomy or who had undergone colectomy but had ≥ 10 cm of large intestine remaining. For IDP, colorectal polyps of ≥ 10 mm were removed, followed by polyps of ≥ 5 mm. The primary end point was the presence/absence of colectomy during a 5-year intervention period. RESULTS: 222 patients were eligible, of whom 166 had not undergone colectomy, 46 had undergone subtotal colectomy with ileorectal anastomosis, and 10 had undergone partial resection of the large intestine. During the intervention period, five patients (2.3 %, 95 % confidence interval [CI] 0.74 %-5.18 %) underwent colectomy, and three patients died. Completion of the 5-year intervention period without colectomy was confirmed in 150 /166 patients who had not undergone colectomy (90.4 %, 95 %CI 84.8 %-94.4 %) and in 47 /56 patients who had previously undergone colectomy (83.9 %, 95 %CI 71.7 %-92.4 %). CONCLUSION: IDP in patients with mild-to-moderate FAP could have the potential to be a useful means of preventing colorectal cancer without implementing colectomy. However, if the IDP protocol was proposed during a much longer term, it may not preclude the possibility that a large proportion of colectomies may still need to be performed.

Impact of pathological complete response following neoadjuvant chemotherapy (gemcitabine, nab-paclitaxel, S-1) and radiation for borderline resectable pancreatic cancer: a case report and review of literature.

BACKGROUND: Pancreatic cancer (PC) is a highly lethal malignancy, even if surgical resection is possible (median survival: < 30 months). The prognosis of borderline resectable pancreatic cancer (BR-PC) is even worse. There is no clear consensus on the optimal treatment strategy, including pre/postoperative therapy, for BR-PC. We report a patient with BR-PC who achieved clinical partial response with neoadjuvant chemoradiation therapy (NACRT) and underwent curative resection, resulting in pathological complete response (pCR). CASE PRESENTATION: A 71-year-old man with jaundice and liver dysfunction was referred to our department because of a 48-mm hypo-vascular mass in the pancreatic head with obstruction of the pancreatic and bile ducts and infiltration of superior mesenteric vein and portal vein. The lesion was identified as atypical cells which suggested adenocarcinoma by biopsy, and he was administered NACRT: gemcitabine and nab-paclitaxel, following S-1 and intensity modulated radiation therapy. After reduction in the tumor size (clinical partial response), pancreaticoduodenectomy was performed, and pCR achieved. Postoperative adjuvant chemotherapy with S-1 was initially administered and the patient is currently alive with no recurrence as of 2 years after surgery. CONCLUSIONS: NACRT is a potentially useful treatment for BR-PC that may lead to pCR and help improve prognosis.

A successful operation for giant intra-abdominal desmoid tumors associated with familial adenomatous polyposis: A case report.

Desmoid tumors are benign proliferations of spindle cells originating in fibro-aponeurotic tissue. Many patients with familial adenomatous polyposis (FAP) die from desmoid tumors, which can arise spontaneously but often appear to be surgically induced by prophylactic colectomy. Desmoid tumors are the second most common cause of death in patients with FAP, second to colorectal cancer. Many patients can live a long life with desmoid tumors without symptoms, but when symptoms (ranging from bowel or ureteric obstruction to bowel perforation with abscess and fistula) appear or there is a risk of functional impairment, a wide spectrum of therapies (local and systemic) are valuable in improving the symptoms and controlling the disease. A half-Japanese, half-Caucasian male, who had been diagnosed with intra-abdominal desmoid tumors associated with FAP at age 13, was treated using abdominal wall incision for decompression and chemotherapy from the age of 38. The therapeutic outcome was progressive disease, based on the modified response evaluation criteria in solid tumors (mRECIST), and when he visited our hospital at age 41 the desmoid tumor had invaded the small bowel with a fistula to the abdominal wall. We performed a palliative operation to improve his symptoms, which were fever, abdominal pain, vomiting, and difficulty eating. As the tumor was extremely large and had invaded the small intestine, massive resection including the small intestine was required. To prepare for anticipated massive bleeding, a balloon catheter was placed in the superior mesenteric artery just prior to surgery. Although the operation was extremely difficult, following surgery the patient regained his ability to eat and when discharged was ambulatory and without short-bowel syndrome. We report our experience treating one of the largest reported intraperitoneal desmoid tumors. Resection resulted in a good postoperative course, with improved quality of life and prognosis.

[A Case of Gallbladder Cancer with Long Survival Treated with Resection after Downstaging with GC Therapy].

A 68-year-old woman with a chief complaint of obstructive jaundice was referred to our hospital. She was diagnosed with gallbladder cancer with invasion to the liver, extrahepatic bile duct, right hepatic artery and portal vein. After endoscopic retrograde biliary drainage, she received chemotherapy with gemcitabine and cisplatin. After 9 courses, the size of the tumor and the lymph nodes decreased, and we planned surgery. There were no unresectable factors, and the right hepatic artery and portal vein were detached from the tumor. We performed a subtotal stomach-preserving pancreaticoduodenectomy and gallbladder bed resection. We then performed adjuvant chemotherapy with S-1 for 1 year. The patient remains alive without recurrence, 5 years after the surgery. We report the case of advanced gallbladder cancer with downstaging after GC therapy.

Mesh repair under the anterior lamina of the rectus sheath (MUAR) for abdominal incisional hernia.

PURPOSE: Abdominal incisional hernia is a frequent complication of major abdominal operations. Our method of performing mesh repair under the anterior lamina of the rectus sheath (MUAR) involves placing mesh between the dorsal surface of the anterior rectus sheath and the rectus abdominis muscle. We evaluated the short-term and long-term outcomes of our MUAR method. METHODS: The subjects of this retrospective study were 80 patients with abdominal incisional hernia, who underwent MUAR at our hospital between August, 2009 and September, 2018. We investigated the rate of recurrence and postoperative complications in these patients, who were followed-up postoperatively for at least 18 months. Patients who completed all visits were then followed-up further with questionnaires. RESULTS: The recurrence rate after MUAR was 0%. Postoperative complications consisted of subcutaneous wound infections in two patients (2.5%), successfully treated with wound cleansing and antibiotics; and subcutaneous hematoma in three patients (3.8%), which was spontaneously absorbed in two patients, and removed in one. There were no other complications, such as seroma, intestinal obstruction, mesh infection and bulging, or prolonged postoperative pain. CONCLUSION: Mesh repair under the anterior lamina of the rectus sheath is simple and safe with positive short-term and long-term outcomes, suggesting that it is a good option for incisional hernia repair.

Clinical outcomes of laparoscopic radiofrequency ablation of single primary or recurrent hepatocellular carcinoma (≤3 cm).

PURPOSE: Percutaneous radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC) has some limitations such as poor sonic window and injury to adjacent organs. The laparoscopic approach has been suggested as an alternative option. The aim of this study was to show the safety and efficacy of laparoscopic RFA for single, small (≤3 cm), and primary or recurrent HCC that is not suitable for percutaneous RFA or surgical resection. METHODS: We reviewed the cases of 37 patients (32 men and 5 women, mean age 61 ± 8.1 years) who underwent laparoscopic RFA for single, small HCC (≤3 cm) that was unsuitable for percutaneous RFA or surgical resection. RESULTS: The technical success rate was 94.6% and 34 patients (95%) had no complications. There were no conversions to open RFA and no operative mortality. The primary effectiveness rate 1 month after the procedure was 100%. The overall recurrence rates at 3, 6, 12, and 24 months after the laparoscopic RFA were 8.1%, 14.4%, 25%, and 35.7%, respectively. The local tumor progression rate was 4.2% at 6 months and 8.7% at 9 months. CONCLUSION: Laparoscopic RFA is a safe and effective treatment for HCC cases that are unsuitable for percutaneous RFA.

Nonanatomical resection is comparable with anatomical resection in solitary hepatocellular carcinoma <5 cm in the right posterior section.

Anatomical resection (AR) is superior to nonanatomical resection (NAR) in theory, but the actual clinical benefit of AR for hepatocellular carcinoma (HCC) is controversial due to the substantial heterogeneity of HCC. Here, we retrospectively compared AR and NAR outcomes for solitary hepatocellular carcinoma (HCC) <5 cm in the right posterior section (RPS) and investigated the risk factors for HCC recurrence and liver-related mortality.The study included 99 consecutive patients who underwent curative surgical resection of an HCC in the RPS (S6 and S7) between January 2003 and December 2009. Each patient had a solitary HCC <5 cm and a noncirrhotic liver.The median estimated blood loss during operation and median operative time were significantly worse in the AR group. In addition, the median tumor size and incidence of microvascular invasion were significantly worse in the AR group. The 1-, 3-, and 5-year disease-free survival rates were 74.1%, 66.3%, and 58.2% in the AR group and 84.7%, 64.4%, and 48.2% in the NAR group, respectively (P = 0.172). The corresponding liver-related overall survival rates were 96.3%, 84.7%, and 77.0% in the AR group and 97.2%, 90.1%, and 88.7% in the NAR group, respectively (P = 0.335). NAR was not associated with HCC recurrence or liver-related mortality in multivariate analysis.The outcomes of NAR for a solitary HCC <5 cm in the RPS are comparable to those achieved with AR with respect to long-term liver-related overall survival and disease-free survival.

miR-34a inhibits differentiation of human adipose tissue-derived stem cells by regulating cell cycle and senescence induction.

MicroRNAs (miRNAs) are critical in the maintenance, differentiation, and lineage commitment of stem cells. Stem cells have the unique property to differentiate into tissue-specific cell types (lineage commitment) during cell division (self-renewal). In this study, we investigated whether miR-34a, a cell cycle-regulating microRNA, could control the stem cell properties of adipose tissue-derived stem cells (ADSCs). First, we found that the expression level of miR-34a was increased as the cell passage number was increased. This finding, however, was inversely correlated with our finding that the overexpression of miR-34a induced the decrease of cell proliferation. In addition, miR-34a overexpression decreased the expression of various cell cycle regulators such as CDKs (-2, -4, -6) and cyclins (-E, -D), but not p21 and p53. The cell cycle analysis showed accumulation of dividing cells at S phase by miR-34a, which was reversible by co-treatment with anti-miR-34a. The potential of adipogenesis and osteogenesis of ADSCs was also decreased by miR-34a overexpression, which was recovered by co-treatment with anti-miR-34a. The surface expression of stem cell markers including CD44 was also down-regulated by miR-34a overexpression as similar to that elicited by cell cycle inhibitors. miR-34a also caused a significant decrease in mRNA expression of stem cell transcription factors as well as STAT-3 expression and phosphorylation. Cytokine profiling revealed that miR-34a significantly modulated IL-6 and -8 production, which was strongly related to cellular senescence. These data suggest the importance of miR-34a for the fate of ADSCs toward senescence rather than differentiation.

Non-thermal atmospheric pressure plasma preferentially induces apoptosis in p53-mutated cancer cells by activating ROS stress-response pathways.

Non-thermal atmospheric pressure plasma (NTAPP) is an ionized gas at room temperature and has potential as a new apoptosis-promoting cancer therapy that acts by generating reactive oxygen species (ROS). However, it is imperative to determine its selectivity and standardize the components and composition of NTAPP. Here, we designed an NTAPP-generating apparatus combined with a He gas feeding system and demonstrated its high selectivity toward p53-mutated cancer cells. We first determined the proper conditions for NTAPP exposure to selectively induce apoptosis in cancer cells. The apoptotic effect of NTAPP was greater for p53-mutated cancer cells; artificial p53 expression in p53-negative HT29 cells decreased the pro-apoptotic effect of NTAPP. We also examined extra- and intracellular ROS levels in NTAPP-treated cells to deduce the mechanism of NTAPP action. While NTAPP-mediated increases in extracellular nitric oxide (NO) did not affect cell viability, intracellular ROS increased under NTAPP exposure and induced apoptotic cell death. This effect was dose-dependently reduced following treatment with ROS scavengers. NTAPP induced apoptosis even in doxorubicin-resistant cancer cell lines, demonstrating the feasibility of NTAPP as a potent cancer therapy. Collectively, these results strongly support the potential of NTAPP as a selective anticancer treatment, especially for p53-mutated cancer cells.

The preventive effects of low-dose enteric-coated aspirin tablets on the development of colorectal tumours in Asian patients: a randomised trial.

OBJECTIVE: To evaluate the influence of low-dose, enteric-coated aspirin tablets (100 mg/day for 2 years) on colorectal tumour recurrence in Asian patients with single/multiple colorectal tumours excised by endoscopy. DESIGN: A double-blinded, randomised, placebo-controlled multicentre clinical trial was conducted. PARTICIPANTS: 311 subjects with single/multiple colorectal adenomas and adenocarcinomas excised by endoscopy were enrolled in the study (152 patients in the aspirin group and 159 patients in the placebo group). Enrolment began at the hospitals (n=19) in 2007 and was completed in 2009. RESULTS: The subjects treated with aspirin displayed reduced colorectal tumourigenesis and primary endpoints with an adjusted OR of 0.60 (95% CI 0.36 to 0.98) compared with the subjects in the placebo group. Subgroup analysis revealed that subjects who were non-smokers, defined as those who had smoked in the past or who had never smoked, had a marked reduction in the number of recurrent tumours in the aspirin-treated group. The adjusted OR for aspirin treatment in non-smokers was 0.37 (CI 0.21 to 0.68, p<0.05). Interestingly, the use of aspirin in smokers resulted in an increased risk, with an OR of 3.44. In addition, no severe adverse effects were observed in either group. CONCLUSIONS: Low-dose, enteric-coated aspirin tablets reduced colorectal tumour recurrence in an Asian population. The results are consistent with those obtained from other randomised controlled trials in Western countries. THE CLINICAL TRIAL REGISTRY WEBSITE AND THE CLINICAL TRIAL NUMBER: http://www.umin.ac.jp (number UMIN000000697).

[A case of synchronous cancer of the gall bladder, common bile duct, and the papilla of vater].

A 58-year-old man was diagnosed with liver dysfunction during a health exam and subsequently visited a doctor. Abdominal ultrasonography revealed space-occupying lesions in the gall bladder and bile duct, and he was hospitalized for further examination and treatment. Computed tomography (CT), endoscopic retrograde cholangiopancreatography (ERCP), and magnetic resonance cholangiopancreatography (MRCP) revealed double cancer of the gall bladder and bile duct with pancreaticobiliary maljunction (PBM), and we performed a pancreatoduodenectomy. Pathological examination revealed gall bladder and bile duct cancer, and severe dysplasia of the papilla of Vater. We diagnosed synchronous triple cancer because none of the cancers had continuity or vascular invasion. Each cancer was at Stage I, and the patient has survived for 2 years and 6 months without recurrence and no additional treatment. PBM is a mutation of the junction of the pancreatic and bile ducts outside of the duodenal wall, and is a known complication of biliary tract cancer due to the reflux of pancreatic juice and bile. Because K-ras and p53 gene mutations occur in the biliary tract mucosal epithelium, PBM increases the risk of developing multicentric cancer. It is important to consider the existence of double cancer when biliary tract cancer is detected in a PBM patient.

[A case of postpancreaticoduodenectomy local recurrence successfully treated with extended resection].

A 68 -year-old man underwent a pancreaticoduodenectomy after being diagnosed with primary duodenal cancer. The postoperative pathological diagnosis was tub2, SE, ly1, v1, panc3, pn+, N0. Although adjuvant chemotherapy was administered, local recurrence in the portal region was detected 18 months later. The recurrent tumor pressed against the region of the bile duct anastomosis, which caused obstructive jaundice. After serum bilirubin levels were reduced, resection of the recurrent tumors was performed. This required resection of the transverse colon, parts of the portal vein, and the inferior vena cava. The bile duct anastomotic region, which had been infiltrated by the tumor, was excised and rebuilt. The postoperative pathological diagnosis was tub2. The patient continued to receive adjuvant chemotherapy and showed no signs of recurrence 9 months after surgery. Extended resection for local recurrences of primary duodenal cancer may be an effective means of disease control.

[A case of extragastrointestinal stromal tumor with peritoneal dissemination].

Here, we present the case of a 60-year-old man in whom abdominal computed tomography showed a solid abdominal tumor (11 cm in diameter) in the pelvic space, with widely disseminated nodular lesions. Emergency surgery was performed following the rapid onset of intense abdominal pain. Peritoneal disseminations were widespread and the tumor was confirmed to be in the pelvic space. The tumor was not connected to any segment of the intestinal tract but rather to the retroperitoneum. Immunohistochemical staining was positive for c-kit (exon 11 mutation) and CD34 but negative for S-100 protein. Careful postoperative examination did not reveal any lesions in the upper or lower alimentary tract. On the basis of these findings we diagnosed the tumor as an extragastrointestinal stromal tumor (EGIST) originating from the retroperitoneum. After surgery, intravenous infusion of imatinib was started at a full dose of 400mg/day; however, owing to strong adverse effects, the dose was reduced to 200mg/day. Despite halving the dose, the patient has remained lesion-free according to computed tomography for 36 months after the operation. Low-dose imatinib chemotherapy remained efficacious in controlling progression in this case.

Cyclin-dependent kinase 4 signaling acts as a molecular switch between syngenic differentiation and neural transdifferentiation in human mesenchymal stem cells.

Multipotent mesenchymal stem/stromal cells (MSCs) are capable of differentiating into a variety of cell types from different germ layers. However, the molecular and biochemical mechanisms underlying the transdifferentiation of MSCs into specific cell types still need to be elucidated. In this study, we unexpectedly found that treatment of human adipose- and bone marrow-derived MSCs with cyclin-dependent kinase (CDK) inhibitor, in particular CDK4 inhibitor, selectively led to transdifferentiation into neural cells with a high frequency. Specifically, targeted inhibition of CDK4 expression using recombinant adenovial shRNA induced the neural transdifferentiation of human MSCs. However, the inhibition of CDK4 activity attenuated the syngenic differentiation of human adipose-derived MSCs. Importantly, the forced regulation of CDK4 activity showed reciprocal reversibility between neural differentiation and dedifferentiation of human MSCs. Together, these results provide novel molecular evidence underlying the neural transdifferentiation of human MSCs; in addition, CDK4 signaling appears to act as a molecular switch from syngenic differentiation to neural transdifferentiation of human MSCs.

Cross-talk between BubR1 expression and the commitment to differentiate in adipose-derived mesenchymal stem cells.

BubR1 mitotic checkpoint kinase monitors attachment of microtubules to kinetochores and links regulation of the chromosome-spindle attachment to mitotic checkpoint signaling. Defects in BubR1-mediated signaling severely perturb checkpoint control and are linked to diseases such as cancer. Studies using BubR1 mouse models suggest that BubR1 activities prevent premature aging and infertility. In this study, we show that BubR1 depletion in human adipose-derived mesenchymal stem cells (ASCs) precedes loss of the differentiation potential and induction of replicative senescence. These effects occur independently of p16(INK4A) expression and may involve DNA methylation. Our results reveal a new and unsuspected feature of BubR1 expression in regulation of adult stem cell differentiation.

Obesity as a risk factor for GERD in Japan.

BACKGROUND: In Europe and the United States, it is known that obesity, which is increasing, is closely associated with gastroesophageal reflux disease (GERD), but in Japan no definite consensus has been reached on this relationship. Clarification of the relationship between the two is an important issue. METHODS: After screening, gastrointestinal endoscopic examinations were conducted on 1813 subjects who were surveyed using a questionnaire in which they recorded body weight, height, weight loss or gain, chief complaints, and underlying disease to prospectively examine the relationship between obesity and GERD. Differences in GERD prevalence and esophageal hiatal hernia prevalence in thin (body mass index less than 18.5 kg/m2), normal (18.5 to 25.0), and obese (greater than 25.0) subjects were examined, and the differences in GERD prevalence in patients with weight loss or gain were also investigated. RESULTS: GERD prevalence was 20.96% in the thin group, 24.42% in the normal group, and 31.86% in the obese group, indicating a significantly higher prevalence in the obese group compared with the other groups. The prevalence of hernia was also significantly higher in the obese group. GERD prevalence in the weight gain group was significantly higher than in the unchanged weight group and weight loss group. CONCLUSIONS: Both GERD prevalence and the prevalence of hernia were significantly higher in obese subjects, and the prevalence of GERD in subjects who had gained weight was also significantly higher. From these results, it was concluded that obesity is a risk factor for GERD in Japan.

Cervical heterotopic pregnancy after assisted reproductive technology successfully treated with only simple embryo aspiration: a case report.

BACKGROUND: The etiology of cervical heterotopic pregnancy is unknown, but most are associated with assisted reproductive techniques. Various types of conservative management to save the intrauterine pregnancy have been attempted. CASE: A 35-year-old woman conceived after in vitro fertilization/embryo transfer for primary malefactor infertility. At 7(3/7) weeks of gestation, only the embryo was aspirated without fluid. Delivery of a healthy infant at 35 weeks was successful. CONCLUSION: Simple embryo aspiration under transvaginal ultrasonography guidance can be used in cervical heterotopic pregnancy.

Gene expression profiling of the pre-implantation mouse embryo by microarray analysis: comparison of the two-cell stage and two-cell block.

To improve our understanding of the molecular mechanisms underlying early embryo development, further characterization of gene activity in oocytes and embryos is urgently required. The transition from the two-cell to four-cell stage is particularly important in pre-implantation embryonic development, as it involves transcriptional reprogramming and cellular differentiation. In this study, we used a 7.4 K cDNA microarray to screen mRNA transcript levels in the pre-implantation mouse embryo. Real-time PCR was used to confirm microarray data. We profiled 7,410 genes and identified 4,562 genes that were differentially expressed in the pre-implantation embryo. We selected a total of 248 genes with significant expression changes that are functionally involved in the two-cell and two-cell block embryo. Of these genes, 114 were down-regulated and the remainder (n=134) were up-regulated in the two-cell embryo. This study provides a developmental map of a large number of genes in the pre-implantation mouse embryo with particular emphasis on gene expression in the two-cell embryo and two-cell block embryo. Further investigations based on this data will provide a better understanding of the effects of various external conditions and may facilitate comparative analysis of pre-implantation development in other mammalian species, including human.