We isolated a 204-base pair carcinoembryonic antigen (CEA) promoter core region from a CEA-producing human colorectal carcinoma (CRC) and constructed retrovirus vectors carrying the expression cassette consisting of the CEA promoter core region and the cytosine deaminase (CD) gene. pCD2 retrovirus carrying the CD gene directed by the retrovirus long terminal repeat promoter served as a control vector. An in vitro study showed that the CEA promoter conferred CEA-producing cell-selective CD expression, specifically when the CD expression cassette was inserted into the 3' long terminal repeat of the retrovirus vector. CD-modified CRC xenografts in nude mice were sensitive to 5-fluorocytosine and caused a profound bystander effect on the unmodified CRC. When nude mice harboring intraperitoneally disseminated CRCs were injected intraperitoneally with the CD expression cassette-carrying retrovirus-producing cells, CD transduction into the disseminated CRCs and bone marrow (BM) was observed. CD expression was, however, restricted to CRCs, and it was observed in both CRCs and BM of mice injected with pCD2 retrovirus-producing cells, resulting in better therapeutic outcomes without BM suppression. These results indicate that effective and safe in vivo gene therapy for CRC may be feasible by transferring the CD gene controlled by the CEA promoter core region.

Animals↗

PubMedDate not supplied

Rapid molecular genetic subtyping of serotype M1 group A Streptococcus strains.

Serotype M1 group A Streptococcus, the most common cause of invasive disease in many case series, generally have resisted extensive molecular subtyping by standard techniques (e.g., multilocus enzyme electrophoresis, pulsed-field gel electrophoresis). We used automated sequencing of the sic gene encoding streptococcal inhibitor of complement and of a region of the chromosome with direct repeat sequences to unambiguously differentiate 30 M1 isolates recovered from 28 patients in Texas with invasive disease episodes temporally clustered and thought to represent an outbreak. Sequencing of the emm gene was less useful for M1 strain differentiation, and restriction fragment length polymorphism analysis with IS1548 or IS1562 as Southern hybridization probes did not provide epidemiologically useful subtyping information. Sequence polymorphism in the direct repeat region of the chromosome and IS1548 profiling data support the hypothesis that M1 organisms have two main evolutionary lineages marked by the presence or absence of the speA2 allele encoding streptococcal pyrogenic exotoxin A2.

Amino Acid Sequence↗

PubMedDate not supplied

Assessment of carotid artery stenosis by MR angiography: comparison with x-ray angiography and color-coded Doppler ultrasound.

PURPOSE: To compare magnetic resonance angiography (MRA) with duplex Doppler ultrasound (US) and x-ray angiography (XRA) in the evaluation of the carotid bifurcation. METHODS: The carotid arteries of 61 patients were studied using MRA, US, or XRA; 31 of the patients underwent all three examinations. MRA included both 2D and 3D time-of-flight sequences. Internal and external carotid artery origins were graded normal, mild, moderate, severe, or critical stenosis, or complete occlusion by each of the three studies. RESULTS: Spearman rank correlations of both internal and external carotid artery grades were 0.85 (MRA and XRA), 0.69 (MRA and US), and 0.73 (XRA and US). For internal carotid artery origins only, the correlations were 0.94 (MRA and XRA), 0.85 (MRA and US), and 0.82 (XRA and US). Of discrepancies in internal carotid artery interpretation greater than one grade, seven resulted from US error, three from MRA error, and one from XRA error. A 2-cm partially thrombosed aneurysm detected by US and MRA was missed by XRA. Of 16 possible ulcers on XRA, 11 were noted by MRA, none by US. CONCLUSIONS: MRA and XRA are similar in assessment of carotid bifurcation stenosis. MRA, like US, permits direct visualization of plaque. This preliminary study suggests that MRA may be used to clarify equivocal findings of US, or replace XRA in presurgical planning.

Aged↗

PubMedDate not supplied

Fatty mass in the inferior vena cava at CT: lipoma or normal variant?

Fatty mass in the intrahepatic portion of the inferior vena cava (IVC) is an unusual lesion. We describe two cases of fatty mass appearing in the lumen of the IVC on CT and MRI study. We assume that this can be regarded as a benign process, and is mostly a normal variant.

Adipose Tissue↗