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Biomedical subjects

J M Chang

Publications and source records attributed to J M Chang.

At least 73 records · Page 4Linked to original sources
PubMed1989

Gene transfer into hemopoietic stem cells using retroviral vectors.

Gene transfer to hemopoietic cells offers a variety of new approaches to the experimental hematologist as well as potentially providing a means for correcting a number of genetic disorders of humans. From the experimental viewpoint, gene transfer utilizing retroviral vectors introduces new methods for analyzing hemopoietic cell lineages, and the effects of over-expression of genes affecting hemopoietic cell proliferation and differentiation. The unique properties of retroviral vectors and the optimized methods currently in use to infect hemopoietic cells are represented as a brief review of a rapidly expanding new field of experimental hematology.

Animals↗
PubMed1989

Transcatheter arterial chemoembolization for hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) was treated with transcatheter arterial chemoembolization (TACE) in a sample of 129 patients. The cumulative survival rate was 49% at 1 year and 22% at 2 years. The median survival time was 11.9 months. The survival rates at 1 year of 84 patients in Child's group A and 27 in Child's group B were 56% and 40%; out of 52 HCC patients with portal vein patent and 77 with portal vein invasion 75% and 40% survived, and the 1-year survival rates for 33 HCC patients with capsule intact, 14 with capsule broken and 82 with no capsule were 85%, 65% and 40% respectively. From the above results there were statistically significant differences in survival time in those with good clinical performance status by Child's classification, those showing patency of the portal vein and those where the capsule was present. Therefore, we would like to recommend, TACE of HCC in well-selected patients presenting with good clinical status, patency of the portal vein and without broken capsule, in order to achieve better clinical results.

Adult↗
PubMed1989

Long-term exposure to retrovirally expressed granulocyte-colony-stimulating factor induces a nonneoplastic granulocytic and progenitor cell hyperplasia without tissue damage in mice.

Murine marrow cells infected with a retroviral vector (MPZen) bearing a granulocyte-colony-stimulating factor (G-CSF) cDNA insert were transplanted into lethally irradiated recipients to study the effects of autocrine production of G-CSF in normal hemopoietic cells. Most animals remained healthy with no evidence of tissue damage throughout the observation period (4-30 wk) despite high circulating G-CSF levels (range 2,000-26,000,000 U/ml). A dramatic neutrophilic granulocytosis was observed in all hemopoietic tissues with neutrophilic infiltration occurring in the lung and liver. Spleen, peritoneal, and peripheral blood cellularity increased approximately three-, two-, and eightfold, respectively, but total bone marrow cell counts remained unchanged. Progenitor cell numbers granulocyte-macrophage colony-forming cell (GM-CFC), granulocyte colony-forming cell (G-CFC), burst-forming unit-erythroid (BFU-E), colony-forming unit-erythroid (CFU-E) and mixed colony-forming cells (Mix-CFC) were elevated between 10-100-fold in the spleen, peritoneal cavity, and peripheral blood, but were unaffected or slightly depressed in the marrow. No tumors developed in syngeneic recipients transplanted with bone marrow or spleen cells from such mice, confirming the nonneoplastic nature of the hyperplasia induced by chronic G-CSF stimulation. These experiments also indicated the stable integration of MPZen vectors in infected cells, as evident from the continuous expression of the inserted gene for at least 6 mo, and from the ability of infected stem cells from the primary recipients to express the gene in lethally irradiated secondary recipients.

Animals↗
PubMed1981

The effect of daily low dose gamma irradiation on growth and differentiation of human myeloid leukaemic bone marrow in diffusion chambers.

Bone marrow from each of 8 untreated patients with myeloproliferative disorders was grown in diffusion chambers in 760 rad total body irradiated rats. Rats were then exposed to 11.5, 57.5, or 108.5 rad daily for 14-2l d and cell growth compared to that detected in unirradiated chambers. Cells from acute myelogenous leukaemia patients exposed to 11.5 rad per d grew for 11-21 d and there was no consistent stimulation of differentiation of immature granulocytic cells to mature granulocytes that was attributable to irradiation. Cells from a chronic myeloid leukaemia patient in chronic phase or blast crisis, and a polycythaemia vera patient with myeloid metaplasia showed significant morphologic differentiation from immature to mature granulocytes in control chambers with no additional effect of daily irradiation. Marrow specimens from 2 AML patients exposed to each of 3 daily dose fractions over 14 d revealed a dose-dependent decrease in immature granulocytes with no persistent increase in mature granulocytes. In both irradiated and control chambers, macrophages increased over 21 d. Thus, cells from patients with myeloproliferative disorders may not necessarily differentiate to mature granulocytes following in vivo exposure to ionizing irradiation.

Adult↗
PubMedDate not supplied

CT of the duodenojejunal junction.

To determine the location of the duodenojejunal junction (DJJ) at computed tomography (CT), we retrospectively reviewed 309 consecutive CT examinations. These included 162 men and 127 women (mean age = 57 years old, range = 11-85 years old). Some people received more than one examination. The clinical indications included various kinds of neoplasms, inflammations, congenital lesions, trauma, and other conditions. The DJJ was defined as the first sectioned ascending duodenum whose major part lies to the right side of the crossing part of the inferior mesenteric vein over the immediate beginning of the jejunum. Forty-nine examinations were excluded due to distortion of the DJJ by contiguous pathologic processes or nonadministration of intravenous contrast medium. In 36 examinations, the junctions were not identified. In the successfully identified 224 examinations, the DJJ was located to the left in 75 (33.5%), in the left half in 87 (38.8%), and in the right half or to the right of the vertebral body in 4 (1.8%) examinations. The midline of the DJJ was along the left margin and in the midline of the vertebral body in 53 (23.7%) and 5 (2.2%) examinations. In the anteroposterior direction, it was totally in front of the aorta in 189 (84.4%) and within the projected contour of the aorta in 11 (4.9%) examinations. The midline of the DJJ was along the anterior margin of the aorta in 24 (10.7%) examinations. Its cephalocaudal position was at the upper L1 in 36 (16.1%), lower L1 in 70 (31.3%), upper L2 in 75 (33.5%), and lower L2 in 21 (9.4%) examinations even though it ranged from upper T12 to upper L3.(ABSTRACT TRUNCATED AT 250 WORDS)

Contrast Media↗
PubMedDate not supplied

CT of gastritis cystica polyposa.

Gastritis cystica polyposa (GCP) is an uncommon lesion that usually occurs at the gastroenterostomy site, although occasionally it can be found in an unoperated stomach. We present a rare case of GCP which presented as a large polypoid mass in the gastric fundus and contained cystic components demonstrable on preoperative computed tomography.

Cysts↗
PubMedDate not supplied

CT of small bowel ischemia.

We evaluated the computed tomographic (CT) features of small bowel (SB) ischemia and necrosis and correlated the findings with clinical outcome or patient prognosis. Sixty-eight surgically or angiographically proved cases of SB ischemia were retrospectively reviewed. The CT features of intestinal ischemia were divided into three groups: (A) thinned bowel wall with poor enhancement, intramural gas, or portal venous gas; (B) thickened SB wall without superior mesenteric vein thrombosis; and (C) thickened SB wall with superior mesenteric vein thrombosis or intussusception. The evaluated factors included bowel wall or mucosal enhancement pattern, SB dilatation, mesenteric edema, and CT evidence of narrowing or occlusion of the superior mesenteric artery or vein. The bowel necrosis rates and mortalities were compared with chi-square test. Oral contrast material was not administered. Intramural gas and SB dilatation were associated with a higher bowel necrosis rate (eight of eight, 100%, and 17 of 21, 81%, respectively) in group A. Poor mucosal enhancement of the thickened bowel wall indicated a higher bowel necrosis rate in groups B (six of seven, 86%) and C (12 of 12, 100%) than did normal mucosal enhancement. Only intramural gas was accompanied with a higher mortality (six of eight, 75%). Intramural gas of a thinned bowel wall and poor mucosal enhancement of a thickened small bowel wall are useful signs of bowel necrosis. Intramural gas would indicate poor patient prognosis.

Aged↗
PubMedDate not supplied

CT of the mesenteric vascular anatomy.

BACKGROUND: To evaluate the appearance of the arrangement of the superior mesenteric artery (SMA) and superior mesenteric vein (SMV) on computed tomography (CT) in normal patients and in patients with abdominal masses. METHODS: One hundred seventy-seven consecutive abdominal CT examinations of 143 adults and two children were reviewed. The relationship of the SMV to the SMA was recorded at four locations: the beginning of the mesenteric vessels and levels 3 cm, 6 cm, and 9 cm caudad to the beginning. The relationship of the SMV to the SMA was divided into four quadrants in relation to the SMA: I, ventral right or directly ventral; II, dorsal right or directly right; III, dorsal left or directly dorsal; and IV, ventral left or directly left. RESULTS: In the beginning of the SMV-SMA complex and levels 3 cm, 6 cm, and 9 cm caudal to the beginning, the SMV was located in quadrant I in 146, 84, 69, and 43 examinations, in quadrant II in 31, 93, 71, and 27 examinations, in quadrant III in zero, zero, five, and three examinations, and in quadrant IV in zero, zero, nine, and 15 examinations, respectively. The cases with SMV inversion had neither malrotation nor adjacent tumor compression. All the cases with an adjacent tumor-induced compression of the SMV-SMA complex had a normal SMV-SMA relationship. CONCLUSION: In the first 3 cm, the SMV is always to the right of the SMA. Caudal to the level of 6 cm, the SMV may be located to the left of the SMA without evidence of malrotation. A midgut nonrotation is more likely to be present when a proximal SMV inversion is coexistent with a rightward direction of the proximal jejunal vessels. A hypothetical depiction of the step-by-step change of the SMV-SMA relationship during embryologic development may explain the arrangement patterns of the mesenteric vessels in normal rotation and midgut nonrotation.

Abdominal Neoplasms↗
PubMedDate not supplied

CT of large small-bowel diverticulum.

The previous reports concerning the computed tomographic (CT) appearances of small bowel diverticulum are usually limited to those of diverticulitis. We present the CT findings of uncomplicated, large small bowel diverticulum in five patients. An interesting coexistence of large small bowel diverticulum and small bowel volvulus will be mentioned. Four patients had recurrent abdominal pain in the past 2 years.

Aged↗
PubMedDate not supplied

CT of agenesis and atrophy of the right hepatic lobe.

BACKGROUND: To identify and differentiate agenesis and severe atrophy of the right hepatic lobe on computed tomography (CT). METHODS: The CT examinations of three cases of agenesis and 11 cases of severe atrophy of the right hepatic lobe were reviewed. We evaluated visibility of the three hepatic veins, the two main portal veins (including their branches if necessary), the dilated intrahepatic ducts, enlargement of the medial and lateral segments of the left lobe and caudate lobe of the liver, presence of a retrohepatic gallbladder, hyperattenuation of the atrophic liver parenchyma, posterolateral interposition of the hepatic flexure of the colon, and upward migration of the right kidney. RESULTS: In the three cases of agenesis, no structure can be recognized as the right hepatic vein, right portal vein, or dilated right intrahepatic ducts. In the 11 cases of severe lobar atrophy, the right portal vein (or its branches) was recognized in eight cases, the right hepatic vein in four cases, and the dilated right intrahepatic ducts in 11 cases. The degree of enlargement of the lateral segment does not necessarily change inversely with the size of the medial segment and the caudate lobe. The retrohepatic gallbladder is present in eight cases (two in agenesis and six in atrophy). The phenomenon of hyperattenuation of the atrophic liver parenchyma was noted in six cases. CONCLUSION: Even though a retrohepatic gallbladder and a severely distorted hepatic morphology due to compensatory hypertrophy of the left and caudate lobes may raise a suspicion of agenesis of the right lobe of the liver, absence of visualization of all of the right hepatic vein, right portal vein and its branches, and dilated right intrahepatic ducts is a prerequisite of the diagnosis of agenesis of the right hepatic lobe on CT. In severe lobar atrophy, at least one of these structures is recognizable.

Adult↗
PubMedDate not supplied

MR measurement of blood flow in the true and false channel in chronic aortic dissection.

Velocity encoded (VEC) cine MR imaging is a new noninvasive technique for the quantification of blood flow velocity in the cardiovascular system. Six patients with type B aortic dissection underwent VEC cine MR imaging at 1.5 T. This technique provides cine MR magnitude and VEC phase images at approximately 16 equally spaced intervals during an average cardiac cycle. A region of interest encompassing a vascular structure, i.e., false channel, provides a spatially averaged velocity for the time interval at which the image was acquired. Interpretation of velocity values from the 16 intervals during the cardiac cycle provides a temporally average velocity. Velocity mapping across the aortic lumen in these six cases showed average spatial and temporal velocity of 13.4 +/- 1.49 cm/s in the true channel and 3.1 +/- 0.84 cm/s in the false channel (p less than 0.05). The peak systolic velocity (temporal peak) was 43.6 +/- 7.20 cm/s in the true channel and 14.3 +/- 2.30 cm/s in the false channel (p less than 0.05). The flow volume per cardiac cycle was not significantly different between the ture (23.1 +/- 5.04 ml/cycle) and false channel (27.1 +/- 10.14 ml/cycle). There was substantial retrograde flow in the false channel of two patients. The intraobserver and interobserver variability was less than 10% (r = 0.98 to 0.99) for the measurement of flow parameters in both the true and the false channel. We conclude that VEC cine MR imaging demonstrates substantial differences in the hemodynamic pattern in the true and false channel in aortic dissection.

Adult↗