Biomedical subjects

Michael Ujiki

Publications and source records attributed to Michael Ujiki.

7 recordsLinked to original sources

PubMed2006

Decreased incidence of left common iliac vein compression in patients with abdominal aortic aneurysms.

OBJECTIVE: Compression of the left common iliac vein (LCIV) by the right common iliac artery is an anatomic variant that may increase the risk for LCIV thrombosis. The incidence of LCIV compression in patients with abdominal aortic aneurysms (AAA) is unknown, however. The aim of this descriptive anatomic study was to determine (1) the incidence of LCIV compression in patients with and without AAA and (2) if endovascular AAA repair acutely alters the incidence of LCIV compression and, hence, the risk of LCIV thrombosis. METHOD: A retrospective analysis of medical records and helical computed tomography (CT) scans was conducted in 100 AAA patients and 100 non-AAA patients (n = 200). Medical records were reviewed for symptoms and risk factors for deep vein thrombosis, and data were reported according to the Joint Society Reporting Standards for acute lower-extremity venous thrombosis. The minor diameters of the aorta, inferior vena cava, and common iliac arteries and veins were measured. For AAA patients, measurements were obtained from preoperative and 30-day postoperative CT scans. RESULTS: The mean age of the study cohort was 38 years (range, 17 to 85 years) for non-AAA subjects and 73 years (range, 51 to 89 years) for AAA subjects. The mean acute lower-extremity venous thrombosis risk factor score was low for both patient groups (non-AAA, 0.82 +/- 0.12; AAA, 2.63 +/- 0.14). Mean compression of the LCIV was 37.8% (range, 0% to 74.8%) for non-AAA patients but only 27.3% (range, 0% to 74.2%; P < .0006) for AAA patients. Of non-AAA patients with venous compression, the right common iliac artery was the compressing structure in 87% of cases. However, of AAA patients with venous compression, the left common iliac artery was the compressing structure in 76% of cases. There was no statistically significant change in the degree of compression of the LCIV before and after endovascular repair (27.3% vs 25.1%, respectively) nor was there a change in the structure that compressed the LCIV. CONCLUSION: Patients with AAA were found to have more tortuous iliac arteries that led to less anatomic compression of the LCIV compared with nonaneurysmal patients. Furthermore, the left common iliac artery was found to compress the LCIV in most of the AAA patients, and the right iliac artery was found to compress the LCIV in most non-AAA patients. Endovascular AAA repair did not acutely alter these anatomic findings. Patients with AAA may therefore be at lower risk of developing LCIV thrombosis owing to the nature of their anatomy.

Adolescent↗

PubMed2005

Pancreatic stellate cells (PSCs) express cyclooxygenase-2 (COX-2) and pancreatic cancer stimulates COX-2 in PSCs.

BACKGROUND: Cyclooxygenase 2 (COX-2), the inducible form of prostaglandin G/H synthase, is associated with several human cancers including pancreatic adenocarcinoma. Pancreatic stellate cells (PSCs) play a central role in the intense desmoplasia that surrounds pancreatic adenocarcinoma. The present study examined COX-2 expression in PSCs. PSCs isolated from normal rats, were cultured and exposed to conditioned medium (CM) from the human pancreatic cell line, PANC-1. METHODS: COX-2 expression was evaluated by immunostaining and western blotting. Proliferation of PSCs was determined by thymidine incorporation and cell counting. RESULTS: COX-2 was found to be constitutively expressed in PSCs, and COX-2 protein was up-regulated by PANC-1 CM. Moreover, the induction of COX-2 by PANC-1 CM was prevented by U0126, an extracellular signal-regulated kinase (ERK) 1/2 inhibitor suggesting that activation of ERK 1/2 is needed for stimulation of COX-2. Finally, NS398, a selective COX-2 inhibitor, reduced the growth of PSCs by PANC-1 CM, indicating that activation of COX-2 is required for cancer stimulated PSC proliferation. CONCLUSION: The results suggest that COX-2 may play an important role in the regulation of PSC proliferation in response to pancreatic cancer.

Animals↗

PubMed2005

N-methylsansalvamide a peptide analogues. Potent new antitumor agents.

Sansalvamide A, a cyclic depsipeptide isolated from a marine fungus of the genus Fusarium, is composed of four hydrophobic amino acids (Phe, two Leu, Val) and one hydroxy acid ((S)-2-hydroxy-4-methylpentanoic acid; O-Leu) with five stereogenic centers all having S-stereochemistry. We have recently synthesized the corresponding cyclic peptide (Gu, W.; Liu, S.; Silverman, R. B. Organic Lett. 2002, 4, 4171-4174) and found that it too has antitumor activity. N-Methylation can enhance potency and selectivity for peptides. Consequently, here we synthesize 12 different N-methylated sansalvamide A peptide analogues and show that for several different tumor cell lines three of these analogues are more potent than the natural product; in pancreatic cells, sansalvamide A shows little activity, but the N-methylsansalvamide peptides are potent cytotoxic agents.

Antineoplastic Agents↗

PubMed2005

Mesenteric ischemia.

Mesenteric ischemia is a morbid, potentially life-threatening disease that is associated with a relatively high mortality, often due to its late diagnosis. Currently, the incidence of mesenteric ischemia in the United States is low; however, the incidence is predicted to increase because of the aging population. Therefore, whether the presentation is acute or chronic in nature, the challenge for the physician remains early diagnosis through a high index of suspicion based on vague and often atypical presentations. Surgical intervention remains the mainstay of therapy. Despite ongoing investigations of the different treatment options, including single vs multivessel bypass, antegrade vs retrograde graft placement, autogenous vs prosthetic conduits, and endovascular vs open surgical repair, many questions remain unanswered. This review summarizes the clinical presentation, diagnosis, and treatment options, including both open and endovascular approaches, for acute and chronic mesenteric ischemia.

Acute Disease↗

PubMed2004

Pancreatic cancer stimulates pancreatic stellate cell proliferation and TIMP-1 production through the MAP kinase pathway.

Pancreatic adenocarcinoma is characterized by an intense desmoplastic reaction that surrounds the tumor. Pancreatic stellate cells (PSCs) are thought to be responsible for production of this extracellular matrix. When activated, PSCs have a myofibroblast phenotype and produce not only components of the extracellular matrix including collagen, fibronectin, and laminin, but also matrix metalloproteinases and tissue inhibitors of metalloproteinases (TIMPs). Since PSCs are found in the stroma surrounding human pancreatic adenocarcinoma, we postulate that pancreatic cancer could impact PSC proliferation and TIMP-1 production. Rat PSCs were isolated and cultured. Isolated PSCs were exposed to PANC-1 conditioned medium (CM) and proliferation, activation of the mitogen-activated protein (MAP) kinase pathway, and TIMP-1 gene induction were determined. Exposure to PANC-1 CM increased PSC DNA synthesis, cell number, and TIMP-1 mRNA (real-time PCR) as well as activating the extracellular-regulated kinase (ERK) 1/2. Inhibition of ERK 1/2 phosphorylation (U0126) prevented the increases in growth and TIMP-1 expression. PANC-1 CM stimulates PSC proliferation and TIMP-1 through the MAP kinase (ERK 1/2) pathway.

Adenocarcinoma↗

PubMed2004

Laparoscopic adhesiolysis for small bowel obstruction.

BACKGROUND: Historically, laparotomy and open adhesiolysis have been the treatment for patients requiring surgery for small bowel obstruction. Laparoscopic adhesiolysis has not gained wide acceptance. The indications and outcomes of laparoscopic adhesiolysis for small bowel obstruction are not well established. The purpose of this paper is to review the literature on laparoscopic adhesiolysis for small bowel obstruction and to discuss patient selection, surgical technique, and outcomes. DATA SOURCES: Medline search from 1980 to 2002. CONCLUSIONS: Laparoscopic adhesiolysis has been shown to be safe and feasible in experienced hands. For selected patients, laparoscopic adhesiolysis offers the advantages of decreased length of stay, faster return to full activity, and decreased morbidity. Patient selection and surgical judgment appear to be the most important factors for a successful outcome.

Algorithms↗

PubMed2004

Iliac vein compression in an asymptomatic patient population.

OBJECTIVE: May-Thurner syndrome is a well-recognized anatomic variant that is associated with the development of symptomatic acute venous thrombosis of the left iliac vein. However, the natural frequency of compression of the left iliac vein and its clinical significance in asymptomatic disease has not been established. Therefore the purpose of this descriptive anatomic study was to determine the incidence of left common iliac vein compression in an asymptomatic population. METHODS: A retrospective analysis of medical records and helical abdominal computed tomography scans was conducted in 50 consecutive patients evaluated in the emergency department because of abdominal pain. Medical records were reviewed for symptoms and risk factors for deep venous thrombosis, and data were collected and reported according to the Joint Society Reporting Standards for acute lower extremity venous thrombosis. All computed tomography was performed with intravenous contrast medium, and 2-mm to 5-mm axial images were obtained. The minor diameter of the common iliac arteries and veins was measured. The technique of transverse image measurement was validated with multiplanar reconstructions and orthogonal diameter measurements in a subset of subjects. Statistical analysis was performed with the Student t test or Spearman rank correlation. RESULTS: Mean age of subjects without symptoms was 40 years (range, 19-85 years), and 60% (n = 30) were female patients. The mean acute lower extremity venous thrombosis risk factor score was 1.16 +/- 0.23 (range, 0-6; maximum possible score, 28). It was surprising that 24% (n = 12) of patients had greater than 50% compression and 66% (n = 33) had greater than 25% compression. Mean compression of the left common iliac vein was 35.5% (range, -5.6%-74.8%). The structure most often compressing the left common iliac vein against the vertebral body was the right common iliac artery (84%). There was no strong correlation between patient age or common iliac artery size and compression of the left common iliac vein. However, women had greater mean compression of the left common iliac vein (women, 41.2% +/- 3.1%; men, 27.0% +/- 3.0%; P =.003). CONCLUSION: Hemodynamically significant left common iliac vein compression is a frequent anatomic variant in asymptomatic individuals. Therefore compression of the left iliac vein may represent a normal anatomic pattern that has thus far been thought of as a pathologic condition.

Adult↗