A novel approach to assessing family history in the prevention of coronary heart disease

Family history serves as the most important risk factor in prevention of coronary heart disease from youth. Prevalent methods of assessing family history, however, have serious drawbacks: a sudden rise of risk when a family member develops the disease; insufficient control for age among family members. We propose a simple quantitative method overcoming such drawbacks. Data on family history were obtained by questionnaires sent to 2,393 male high school students and their cholesterol levels were measured. Family risk from each family member was calculated by (30/Risk age)4, where the risk age was age at onset expressed by decade; if absent, it was replaced by present age or age at death. A mean score in a family served as the family risk. A total of 1,584 students and 17,127 family members were analyzed. The proposed method yielded a statistically significant association (Odds ratio = 1.60; 95% confidence interval: 1.15-2.25) between the family risk (above or below the median) and the student's atherogenic index (above or below the 90th percentile) calculated from cholesterols. This association was stronger than those by conventional methods. The proposed method may be useful in prevention activities and its efficiency needs to be confirmed in other studies.

Fluoroquinolone treatment failure in gonorrhea. Emergence of a Neisseria gonorrhoeae strain with enhanced resistance to fluoroquinolones

BACKGROUND AND OBJECTIVES

Although emergence of clinical isolates of Neisseria gonorrhoeae with decreased susceptibilities to fluoroquinolones and treatment failures in gonorrhea have been reported, there have been no clinical reports that fluoroquinolone treatments actually select quinolone-resistant strains, nor have isolates that exhibited clinically significant resistance been analyzed for resistance mechanisms.

GOALS

To report a case of fluoroquinolone treatment failure in gonorrhea and emergence of a posttreatment isolate with enhanced resistance to fluoroquinolones; and to study mechanisms of quinolone resistance in the isolates from this patient.

STUDY DESIGN

A patient with gonococcal urethritis treated with ofloxacin, 200 mg, three times daily for 5 days is described. Pretreatment and posttreatment isolates were tested for minimum inhibitory concentrations (MICs) of antimicrobial agents and analyzed for alterations in DNA gyrase and topoisomerase IV. They were also examined for ofloxacin uptake.

RESULTS

Treatment failure with multiple doses of ofloxacin was observed in this case of gonorrhea. The pretreatment isolate showed decreased susceptibilities to fluoroquinolones (MIC of ofloxacin, 1.0 mg/l; MIC of ciprofloxacin, 0.25 mg/l), and had amino acid changes of Ser-91-->Phe in GyrA and Ser-87-->Ile in ParC. The posttreatment isolate exhibited an increase in resistance to fluoroquinolones (MIC of ofloxacin, 8.0 mg/l; MIC of ciprofloxacin, 1.0 mg/l). This isolate had identical alterations in GyrA and ParC, but exhibited significantly reduced uptake of ofloxacin. This isolate also showed a small decrease in susceptibilities to cephalosporins.

CONCLUSIONS

Alterations in DNA gyrase and topoisomerase IV confer clinically significant resistance to fluoroquinolones in N. gonorrhoeae strains. Treatment with multiple doses of fluoroquinolones is likely to bring about selection of more fluoroquinolone-resistant strains of N. gonorrhoeae and to influence susceptibilities to cephalosporins.

New indices of ischemic heart disease and aging: studies on the serum levels of soluble intercellular adhesion molecule-1 (ICAM-1) and soluble vascular cell adhesion molecule-1 (VCAM-1) in patients with hypercholesterolemia and ischemic heart disease

It is known that the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) on the surface of vascular endothelial cells is closely related to the formation of early atherosclerotic lesions. In this study, serum soluble ICAM-1(sICAM-1) and soluble VCAM-1(sVCAM-1) were determined by sandwich ELISA both in normal healthy individuals (n = 114) and in patients with hypercholesterolemia (HC, n = 112) or ischemic heart disease (IHD, n = 38) to clarify the significance of the soluble forms of the adhesion molecules in the development of atherosclerotic diseases. IHD patients, not HC patients, showed significant elevation of sICAM-1, but not of sVCAM-1, compared with controls in age and sex-matched subjects. In addition, multiple linear regression analysis showed that sICAM-1 was correlated only to the presence of IHD but not to age and lipids. Multiple logistic regression analysis revealed that sICAM-1 was the most powerful independent predictor of the presence of IHD. On the other hand, sVCAM-1, not sICAM-1, was positively correlated to age. Multiple linear regression analysis showed that age was the most powerful independent predictor of the level of sVCAM-1. These data suggest that sICAM-1 and sVCAM-1 are useful as indices of clinical manifestations of atherosclerosis and aging, respectively.

Identification of alpha-fodrin as a candidate autoantigen in primary Sjögren's syndrome

It is unclear whether organ-specific autoantigens are critical for the development of primary Sjögren's syndrome (SS). A 120-kilodalton organ-specific autoantigen was purified from salivary gland tissues of an NFS/sld mouse model of human SS. The amino-terminal residues were identical to those of the human cytoskeletal protein alpha-fodrin. The purified antigen induced proliferative T cell responses and production of interleukin-2 and interferon-gamma in vitro. Neonatal immunization with the 120-kilodalton antigen prevented the disease in mice. Sera from patients with SS reacted positively with purified antigen and recombinant human alpha-fodrin protein, whereas those from patients with systemic lupus erythematosus and rheumatoid arthritis did not. Thus, the immune response to 120-kilodalton alpha-fodrin could be important in the initial development of primary SS.

Elevated levels of substance P in tears of patients with allergic conjunctivitis and vernal keratoconjunctivitis

BACKGROUND

Recent studies have suggested that the nervous system may participate in inflammatory processes. Substance P (SP) acts as a chemical mediator as well as a neurotransmitter.

OBJECTIVE

In order to clarify the pathogenesis of ocular allergic diseases, we assessed the concentration of SP in tears.

METHODS

Using a highly sensitive and specific double-antibody enzyme immunoassay (EIA), we determined the SP concentration in tears of 10 patients with seasonal allergic conjunctivitis, 10 with atopic dermatitis without keratoconjunctivitis (AD), 13 with vernal keratoconjunctivitis (VKC) and 65 normal controls. Giemsa's staining for brush cytology samples and histocytological study by immunocytochemical staining of giant papillary conjunctival cells from VKC and normal controls was conducted.

RESULTS

The mean SP level was low in the normal controls and AD, whereas patients with seasonal allergic conjunctivitis and VKC showed significant elevation of SP (P < 0.01). Brush cytology samples showed conjunctival epithelial cells with lymphocytes, neutrophils and eosinophils that were not seen in normal subjects. Histocytological examination demonstrated SP positive cells in the conjunctiva of patients with VKC, but not in normal controls.

CONCLUSION

This study suggests that the increased level of SP in tears may contribute to the pathogenesis and severity of ocular allergic diseases.

Rapid screening of point mutations of the Neisseria gonorrhoeae parC gene associated with resistance to quinolones

To detect quinolone resistance-associated mutations within the Asp-86, Ser-87, Ser-88, and Glu-91 codons of the Neisseria gonorrhoeae parC gene, we developed a rapid and simple assay based on amplification of the regions of the parC gene containing the mutations sites by PCR and digestion of the PCR products with restriction enzymes. By using the method of primer-specified restriction site modification, artificial SalI, PstI, EcoRI, and HinfI restriction sites were created in the regions containing the Asp-86, Ser-87, Ser-88, and Glu-91 codons, respectively. The mutations generating alterations at Asp-86, Ser-87, Ser-88, and Glu-91 were detected as failures of SalI, PstI, EcoRI, and HinfI to digest the respective PCR products. Fifty-five clinical strains of N. gonorrhoeae were examined for mutations in the parC gene by this assay. Appropriate mutations at either the Asp-86, Ser-87, Ser-88, or Glu-91 codon were detected in each of 11 strains in which a mutation had previously been observed by DNA sequencing. This rapid and simple assay could be a useful device for screening genetic alterations in the parC gene associated with resistance to quinolones in N. gonorrhoeae.

Heart disease deaths on death certificates re-evaluated by clinical records in a Japanese city

In order to estimate the number of deaths from ischemic heart disease (IHD) in a Japanese city, we reevaluated heart disease deaths among residents aged 25-74 years by examining their clinical records. During the 2-year period from 1987 to 1988, 271 deaths among this population were attributed to heart disease. The recorded underlying cause of death was IHD in 96 cases, heart failure in 123 cases, and other heart disease in 52 cases. Re-evaluation of the cause of death yielded 57 cases of acute myocardial infarction (AMI), 85 cases of sudden death, 37 cases of heart disease other than IHD, and 63 cases of non-heart disease. In the remaining cases, there was insufficient information for evaluation. According to some autopsy studies, about 50% of sudden deaths are due to IHD. Thus, 50% of the number of sudden death cases may be added to the total number of IHD deaths. Accordingly, the total number of IHD deaths may have been 100, ie, 57 cases of AMI plus 43 cases of sudden death. The difference between the number of IHD deaths after re-evaluation and the number for which IHD was recorded as the underlying cause was small, with the former only 4% higher than the latter. The number of false-positives was equal to the number of false-negatives, and hence the number of IHD deaths recorded in this area seems to be close to the actual figure. We speculate that more accurate death certification will result in a decrease in the total number of deaths attributable to heart disease, as in 23% of deaths attributed to heart disease the underlying cause of death was not in fact heart disease.

Structures of cobalt(III)-pepleomycin and cobalt(III)-deglycopepleomycin (green forms) determined by NMR studies

Pepleomycin (PEP) is a metalloglycopeptide that has stronger anticancer activity and less pulmonary toxicity than bleomycin (BLM). PEP, like BLM, exerts its action by binding to and degrading DNA in the presence of oxygen and certain metals. Obtaining detailed structural information of PEP and PEP-DNA complexes is crucial to understanding its anticancer activity. The structures of two green forms of cobalt-PEP species, HO2-Co(III)-PEP (denoted CoPEP) and deglycosylated HO2-Co(III)-PEP (denoted CodPEP) have been obtained by NOE restrained refinements. Earlier studies of the related HO2-Co(III)-BLM A2 proposed that two chiral conformers (form A or B) could exist with either the beta-aminoalanine primary amine (A,NH2) or the mannose carbamoyl nitrogen (M,NH2) as the axial ligand. Analysis of our NOESY data shows convincingly that form A is the most probable conformer with the mannose carbamoyl M,NH2 and the beta-aminoalanine primary amine A,NH2 as the axial ligands in CoPEP and CodPEP, respectively. The NOE cross-peaks resulting from the interactions between the N-terminus (i.e., the metal-binding domain) and the C-terminus of CoPEP and CodPEP have similar patterns, suggesting that they both adopt compact structures with the bithiazole group folded back over the N-terminus.

Retrovirus in salivary glands from patients with Sjögren's syndrome

AIMS

To investigate the possibility of an immune response to retroviral antigens or of detecting retrovirus in Sjögren's syndrome.

METHODS

Retroviruses were sought in labial salivary glands and peripheral blood mononuclear cells from patients with Sjögren's syndrome by immunoblotting assay, immunohistochemical assay, polymerase chain reaction (PCR), reverse transcriptase (RT) activity assay, and transmission electron microscopy.

RESULTS

Sera from five of 15 patients with Sjögren's syndrome (33%) reacted against p24 group specific antigen (gag) of human immunodeficiency virus (HIV). Labial salivary gland biopsy specimens from seven of the 15 patients with Sjögren's syndrome (47%) contained an epithelial cytoplasmic protein reactive with a monoclonal antibody to p24 of HIV. PCR was performed to detect HIV and human T lymphotropic virus type I (HTLV-I) genes from salivary gland tissues and peripheral blood mononuclear cells from patients with Sjögren's syndrome. Mn2+ dependent, Mg2+ independent RT activity was detected in the salivary gland tissues in three of 10 patients. A-type-like retroviral particles were observed in epithelial cells of salivary glands by transmission electron microscopy. Target genes for HIV and HTLV-I were not found in any of the salivary gland tissues or peripheral blood mononuclear cells from Sjögren's syndrome patients.

CONCLUSIONS

The data suggest the presence of an unknown retrovirus similar to HIV in the salivary gland which might be involved in the pathogenesis of a subpopulation in Sjögren's syndrome.

Treatment of branch retinal arterial occlusion with sodium ozagrel, a thromboxane A2 synthetase inhibitor

A 47-year-old woman with branch retinal arterial occlusion treated with sodium ozagrel is described. The patient presented with acute visual field loss in her right eye. Blood tests demonstrated the elevation of beta-thromboglobulin and platelet factor 4. Sodium ozagrel, a thromboxane A2 synthetase inhibitor, 160 mg daily was administered for 14 days. This treatment prevented exacerbation of retinal arterial thrombosis and produced a marked improvement in the visual field loss. Sodium ozagrel may be a useful drug in the treatment of acute retinal arterial occlusion thought to be caused by thrombosis.

[Expression of HGF and c-met/HGF receptor mRNA in brains of normal rats and in phaeochromocytoma cells PC-12 of rats treated with NGF]

Gene expression of HGF and c-met proto-oncogene was examined during rat brain development and in cultured PC-12 cells, using reverse-transcriptase (RT)-polymerase chain reaction (PCR) technique. The both mRNAs of HGF and c-met proto-oncogene were remained at low levels in the middle and late stages of gestation (E-13 and E-18). After birth, and the level of both mRNA expression suddenly increased. During P-1 and P-12, their high level of expression continued and then decreased in P-20 and adult brain. Both HGF mRNA and c-met photo-oncogene mRNA were transiently expressed between day 2 and day 5, and disappeared in cultured PC-12 cells treated with NGF. The neurites of PC-12 cells that were treated with anti-sense oligonucleotides of HGF and c-met proto-oncogene, were shorter and fewer in number than untreated control cells. We conclude that neurite extension of PC-12 cells treated with NGF may ensue by way of c-MET protein activation and signal transduction pathways. Thus, c-MET protein activation and up-regulation of the two mRNAs may also play an important role in neuronal maturation in the developing rat brain.

Expression of aquaporins in the rat ocular tissue

The aquaporins (AQPs) are a rapid growing family of water channel proteins found in animals, plants and microorganisms that raise plasma membrane water permeability required for efficient isosmotic fluid transport. Five homologs of aquaporins (AQP1, AQP2, AQP3, AQP4 and AQP5) have been identified from various mammalian tissues; the expression of these aquaporins in ocular tissues was studied. Semiquantitative expression levels of these aquaporins were determined in ciliary body, cornea, lens, retina, iris and choroid using RT-PCR. Expression levels of AQP1 are highest among the known aquaporins in each rat ocular tissue examined. In cornea, AQP1 is expressed approximately three-fold higher than AQP3 and 2.5 fold higher than AQP5. However, the highest intraocular expressions of AQP3 and AQP5 are in the cornea. In the iris, expression levels of AQP1 are approximately 600-700 fold higher than AQP4 and AQP5. In the ciliary body, the expression levels of AQP1 are approximately ten-fold higher than AQP4, the only other aquaporin expressed. In the lens, the major water channel is AQP1 with detectable levels of AQP4 and AQP5 that are approximately 1000-fold lower than AQP1. In choroid, AQP1 is the only water channel expressed. In retin, AQP1 is expressed approximately six-fold higher than AQP4, the only other aquaporin expressed. However, the highest ocular expression of AQP4 is in retina. AQP2 is not detected in the eye. Finally, the possible physiological roles of aquaporins in maintaining and regulating the aqueous flow, and corneal and lens transparency are discussed.

Antimicrobial activity of a new fluoroquinolone, DU-6859a, against quinolone-resistant clinical isolates of Neisseria gonorrhoeae with genetic alterations in the GyrA subunit of DNA gyrase and the ParC subunit of topoisomerase IV

The in-vitro antimicrobial activity of DU-6859a, a new fluoroquinolone, was tested against 55 clinical isolates of Neisseria gonorrhoeae. The MIC of DU-6859a inhibiting 90% (MIC90) of the isolates with genetic alterations of both the GyrA subunit of DNA gyrase and the ParC subunit of topoisomerase IV was 0.125 mg/L. The MIC90 for isolates with alterations of GyrA alone or without alterations of GyrA or ParC was 0.03 mg/L and 0.004 mg/L, respectively. The potency of DU-6859a against clinical isolates bearing genetic alterations associated with quinolone resistance was significantly greater than that of currently available fluoroquinolones.

Cooperative alkylation by duocarmycin A-distamycin A heterodimer

Duo A (Duo) normally alkylates adenine N3 at the 3' end of A + T-rich sequence in DNA. The addition of another minor groove binder, dist A (Dist), dramatically modulate the site of DNA alkylation by Duo with great acceleration of the reaction rate. In order to examine the mode of alkylation, the kinetics of the reaction under various conditions were examined. Based on the simulation of experimental data, a new reaction pathway was proposed.

Increased blood plasminogen activator inhibitor-1 and intercellular adhesion molecule-1 as possible risk factors of atherosclerosis in Werner syndrome

Werner syndrome is a rare premature aging syndrome accompanied by severe atherosclerosis. The etiology of atherosclerosis is suspected to be due to its complications, namely diabetes mellitus, hyperinsulinemia and hyperlipidemia. But from an autopsy case we found that some other risk factors may be involved in the mechanism of atherosclerosis in this syndrome. Previously we revealed that the plasminogen activator inhibitor-1 (PAI-1) gene was being overexpressed in skin fibroblasts from a patient with this syndrome. PAI-1 is a potent inhibitor of tissue plasminogen activator and a possible risk factor of atherosclerosis. This led us to assess the plasma concentration of PAI-1. Our working hypothesis was that the PAI-1 gene was upregulated or not fully suppressed in cells responsible for the production of PAI-1 in plasma as well as in fibroblasts. The results show a high concentration of plasma PAI-1. One of the well-known physiological substances that induce the PAI-1 gene is tumor necrosis factor-alpha, which also induces other possible risk factors of atherosclerosis, intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1. We found the serum concentrations of ICAM-1 to be elevated in patients with this syndrome. We conclude that high concentrations of PAI-1 and ICAM-1 in blood may be one of the potent causes of severe atherosclerosis in Werner syndrome.

Interleukin-2 gene transduction into freshly isolated lung adenocarcinoma cells with adenoviral vectors

We evaluated the efficiency of gene transduction and of gene expression by adenoviral vectors in human lung adenocarcinoma cells. Freshly isolated cancer cells were collected from pleural effusions in adenocarcinoma patients by centrifugation with a Percoll gradient. Adenoviral vectors resulted in effective gene transduction into human lung cancer cell lines and into freshly isolated lung adenocarcinoma cells. In an experiment using the beta-galactosidase (LacZ) gene, the Adex1CA vector with a regulatory sequence of chicken beta-actin as promoter and an enhancer derived from cytomegalovirus produced a higher transduction ratio and greater expression levels than adenoviral vectors with other promoter systems. Transduction with Adex1CA vectors containing the human interleukin-2 (IL-2) gene (Adex1CAhIL-2) resulted in enhanced secretion of IL-2 from gene-modified lung cancer cells. Treatment with normal human serum inhibited gene transduction by Adex1CAhIL-2 but did not inhibit gene expression after transduction by Adex1CAhIL-2. The secretion of IL-2 from the gene-modified cells, which were irradiated at 100 Gy before transduction, continued for 8 days. In a mouse model, the intrapleural injection of IL-2 gene-modified 3LL cells transduced by Adex1CAhIL-2 could cure the pre-existing lung tumours with malignant pleural effusions to induce tumor-specific immunity. But these therapies did not show any therapeutic benefit on the pre-existing tumor in subcutaneous region. These data suggest a potentially useful but limited clinical role of Adex1CAhIL-2 in gene therapy for lung cancer patients.

Transplantation of genetically marked cardiac muscle cells

We examined the possibility that cardiomyocytes could be genetically marked or modified before being grafted to the heart under conditions applicable to the clinical setting. We used a replication-defective recombinant adenovirus carrying the beta-galactosidase reporter gene, and delivered it to cultured murine fetal cardiac myocytes. Virtually all fetal cardiomyocytes in a primary culture expressed beta-galactosidase 24 hours after recombinant adenovirus infection. These cells were transplanted to the hearts of syngenic adult recipient mice. Expression of the beta-galactosidase gene in the grafted cells was demonstrated by staining with 5-bromo-4-chloro-3-indoyl-beta-D-galactosidase, resulting in a blue color at the histochemical level and an electron-dense deposit on transmission electron microscopic analysis. Gene expression was recognized from 7 days to 12 weeks after transplantation. Implanted cardiomyocytes aligned themselves along the layers of the host myocardium. Formation of gap junctions was demonstrated by transmission electron microscopy. Neither inflammation nor fibrous scar tissue was detectable by histologic analysis. This study demonstrates that ex vivo gene transfer to the heart by means of the adenoviral vector is possible.

In vivo correction with recombinant adenovirus of 4-hydroxyphenylpyruvic acid dioxygenase deficiencies in strain III mice

Tyrosinemia type 3, caused by a genetic deficiency of 4-hydroxyphenylpyruvic acid dioxygenase (HPD) in tyrosine catabolism, is characterized by convulsion, ataxia, and mental retardation. The III mouse is a model of tyrosinemia type 3. HPD activity and protein are defective in the liver and its blood tyrosine levels are elevated, the range being between 1,100 and 1,656 microM. We constructed a recombinant adenoviral vector bearing the human HPD cDNA (AdexCAGhHPD), which is expressed under the control of a potent CAG promoter. III mice were injected with 1.0 x 10(8) to 1.0 x 10(9) pfu of AdexCAGhHPD through the tail vein. When 3.0 x 10(8) - 1.0 x 10(9) pfu were injected, blood tyrosine levels decreased within 3 hr, reached a normal range (under 300 microM), and remained at a low level for 2-6 weeks. Hepatic HPD activities also increased as early as 3 hr after the injection of 5.0 x 10(8) pfu, reached the levels comparable to the control mice in 3-7 days, and then decreased, and correlated well to blood tyrosine. Hepatic HPD expression was confirmed by Northern blot and immunoblot analyses. Histology revealed no difference (gross or microscopic) between the liver injected with AdexCAGhHPD and the control. No significant changes in blood tyrosine levels were noted after the second injection of 5.0 x 10(8) pfu of AdexCAGhHPD. Thus, the intravenous administration of the adenoviral vector bearing a foreign gene seems suitable for transient, early gene transfer into the liver.

Distamycin A modulates the sequence specificity of DNA alkylation by duocarmycin A

Duocarmycin A (Duo) normally alkylates adenine N3 at the 3' end of A + T-rich sequences in DNA. The efficient adenine alkylation by Duo is achieved by its monomeric binding to the DNA minor groove. The addition of another minor groove binder, distamycin A (Dist), dramatically modulates the site of DNA alkylation by Duo, and the alkylation switches preferentially to G residues in G + C-rich sequences. HPLC product analysis using oligonucleotides revealed a highly efficient G-N3 alkylation via the cooperative binding of a heterodimer between Duo and Dist to the minor groove. The three-dimensional structure of the ternary alkylated complex of Duo/Dist/d(CAGGTGGT).d(ACCACCTG) has been determined by nuclear Overhauser effect (NOE)-restrained refinement using 750 MHz two-dimensional NOE spectroscopy data. The refined NMR structure fully explains the sequence requirement of such modulated alkylations. This is the first demonstration of Duo DNA alkylation through cooperative binding with another structurally different natural product, and it suggests a promising new way to alter or modify the DNA alkylation selectivity in a predictable manner.

Soluble CD14 mediates lipopolysaccharide-induced intercellular adhesion molecule 1 expression in cultured human gingival fibroblasts

Intercellular adhesion molecule 1 (ICAM-1) is involved in the accumulation and activation of leukocytes in inflammatory diseases such as periodontitis. As reported previously, ICAM-1 is up-regulated on cultured human gingival fibroblasts (HGF) by exposure to lipopolysaccharide (LPS), suggesting a specific LPS recognition mechanism. We therefore investigated the role of CD14, an LPS receptor, in stimulation of HGF by LPS. Cell surface CD14 antigen was not observed on HGF by flow cytometric analysis. In addition, expression of CD14 mRNA in HGF was not detected by reverse transcription-PCR analysis. Since HGF did not express endogenous CD14, we investigated the role of human serum-derived soluble CD14 (sCD14) in ICAM-1 induction on HGF by LPS. The serum-dependent ICAM-1 induction by LPS was observed in HGF. In medium containing human serum, anti-CD14 antibody inhibited ICAM-1 induction on HGF by LPS. Depletion of sCD14 from human serum markedly reduced ICAM-1 expression on HGF in response to LPS. Supplementation of the serum-free medium with sCD14 alone restored the capacity of HGF to respond to LPS. These results show that induction of ICAM-1 in HGF by LPS does not involve binding to cell surface CD14 but is mediated by serum-derived sCD14.

Efficient gene activation system on mammalian cell chromosomes using recombinant adenovirus producing Cre recombinase

To develop a method for activating genes located on cell chromosomes, an on/off switching unit regulated by the site-specific recombinase Cre was constructed. The switching unit was designed to express firstly the neo gene and secondly the reporter lacZ gene by Cre-mediated excisional deletion of the neo gene. CV1 cell lines bearing the switching unit on a cell chromosome were isolated and activation of the lacZ gene was examined after infection with a Cre-producing recombinant adenovirus. In one cell line virtually 100% of the cells stably expressed the lacZ gene, whereas in another cell line lacZ-expressing cell populations reached only to about 90% and decreased after cell divisions. The Southern blot analyses showed that the latter type of cells contained a head-to-tail array of the switching units, and that consequently the lacZ-expressing units were excised from a cell chromosome and present as extrachromosomal circular DNAs. These results showed that the system offers efficient activation of genes introduced into cell chromosomes and that the organization of the reporter units are important for efficiency and duration of the activated gene expression.

Risk of clot formation with ionic and nonionic contrast media in cerebral angiography. Tama Contrast Media Study Group

RATIONALE AND OBJECTIVES

The introduction of low-osmolality contrast media has improved patient tolerance to angiographic procedures. However, nonionic contrast media may be associated with an increase in the risk of clot formation. The objective of this study was to test whether there is more clotting with nonionic agents than with ionic agents.

METHODS

Ninety-eight patients undergoing transfemoral cerebral angiography were randomly assigned to receive ionic (ioxaglate) (n = 62) or nonionic (iopamidol or iohexol) (n = 36) contrast material. Incidence of clot formation was examined by observation of catheters.

RESULTS

Clot formation was found in 4.8% of patients in the ionic contrast material group and 22.2% of patients in the nonionic contrast material group (P < .05).

CONCLUSION

Nonionic contrast media resulted in a statistically significantly higher incidence of clot formation than ionic media during cerebral catheter angiography. These results suggest that ionic contrast media are preferable in patients with risk of thrombosis.