Alternative splicing of transcripts expressed by the Manduca sexta allatotropin (Mas-AT) gene is regulated in a tissue-specific manner

The Manduca allatotropin (Mas-AT) gene is expressed as at least three mRNA isoforms that differ from each other by alternative splicing. The location at which the alternative exons are included in the mature mRNAs occur within the open reading frame, so that three different propeptides are predicted as translation products. In the pharate adult insect, the major mRNA isoform expressed in the brain and frontal ganglion differs from that expressed in the nerve cord. Examination of the deduced translations of the alternative exons reveals the presence of three additional Mas-AT-like sequences that are flanked by basic amino acid residues. Therefore, the Mas-AT-like sequences present within the gene may be derived from a duplication of an ancestral Mas-AT-like sequence followed by divergence.

Increase in rat plasma antioxidant activity after E. coli lipopolysaccharide administration

It is well recognized that the sensitivity of animals to lipopolysaccharide (LPS) endotoxin varies tremendously. And, it has been recently observed that Sprague-Dawley rats dramatically increase the activity of hepatic endogenous antioxidative enzyme systems after LPS administration. This finding suggests that the relative resistance of rats to LPS may be related to a concomitant increase in the activities of the hepatic antioxidant systems. This study was designed to examine if the above reported hepatic change in rats given LPS could be observed at the systemic level. Male Sprague-Dawley or Wistar rats, weighing 250 - 350 g, were given increasing doses (10 - 100 mg/kg) of LPS i.p. under 1.0% isoflurane anesthesia. Antioxidant capacity (AOC), blood gas analysis, and the cardiovascular parameters of the arterial blood of animals were determined over a 4 hour period following LPS administration. In addition, we studied the effect of pretreatment with the non-specific nitric oxide synthase inhibitor, L-N(G)-Nitroarginine methyl ester hydrochloride (L-NAME), given 50 mg/kg s.c. one and 24 hours before the administration of 20 mg/kg LPS i.p. in Sprague-Dawley rats. Rats given sufficiently high doses of E. coli LPS to produce behavioral effects also showed increased plasma AOCs in the early period after the administration of LPS. Similar changes were noted in Sprague-Dawley and Wistar rat strains, but at different doses that reflect their differential sensitivities to the LPS induced inflammatory response. Also, the resistance of the Sprague-Dawley strain of rats to LPS was not altered by the prior administration of L-NAME, nor was the plasma AOC altered. In conclusion, our study suggests that the rat strains are relatively resistant to develop the toxic signs of LPS in the early period after the administration of LPS, especially in Sprague-Dawley rats. Moreover, endotoxin-induced increases in plasma AOC may contribute to the rats' resistance to LPS intoxication.

Successful interferon alpha therapy in atopic dermatitis of Besnier's prurigo pattern with normal serum IgE and blood eosinophil fraction: randomized case-controlled study

A randomized case-controlled study was carried out to investigate for interferon alpha therapy in atopic dermatitis (AD) of Besnier's prurigo pattern with normal serum IgE and normal blood eosinophil fraction. Interferon alpha therapy was conducted on 14 non-responders to interferon gamma and subsequent thymopentin therapy among 100 atopic dermatitis patients. Eight patients who improved significantly, showed skin lesions of the Besnier's prurigo pattern with normal serum IgE and normal blood eosinophil fraction. For the randomized prospective case-controlled study, 44 patients with the above characteristics were selected. Thirteen Besnier's prurigo patients were treated with interferon alpha therapy, ten with interferon gamma, ten with thymopentin, and the remaining 11 were untreated as the control group. With interferon alpha therapy, 11 out of 13 Besnier's prurigo patients with normal IgE and normal blood eosinophil fraction improved significantly, two out of ten improved with interferon gamma therapy, and none improved with thymopentin therapy or in the untreated control group. Interferon alpha therapy was effective on AD of Besnier's prurigo pattern with normal serum IgE and normal blood eosinophil fraction. These results suggest the possibility of non-IgE-mediated AD and the heterogeneity of atopic dermatitis.

Triptolide and chemotherapy cooperate in tumor cell apoptosis. A role for the p53 pathway

Triptolide (PG490), a diterpene triepoxide, is a potent immunosuppressive agent extracted from the Chinese herb Tripterygium wilfordii. We have previously shown that triptolide blocks NF-kappaB activation and sensitizes tumor necrosis factor (TNF-alpha)-resistant tumor cell lines to TNF-alpha-induced apoptosis. We show here that triptolide enhances chemotherapy-induced apoptosis. In triptolide-treated cells, the expression of p53 increased but the transcriptional function of p53 was inhibited, and we observed a down-regulation of p21(waf1/cip1), a p53-responsive gene. The increase in levels of the p53 protein was mediated by enhanced translation of the p53 protein. Additionally, triptolide induced accumulation of cells in S phase and blocked doxorubicin-mediated accumulation of cells in G(2)/M and doxorubicin-mediated induction of p21. Our data suggest that triptolide, by blocking p21-mediated growth arrest, enhances apoptosis in tumor cells.

Varying expression levels of colony stimulating factor receptors in disease states and different leukocytes

Administration of G-CSF may not always respond in rise of neutrophil counts in different patient population. In order to understand a possible inter-relationship between the G-CSF and GM-CSF induced leukocyte responses and expression levels of receptors for G-CSF (G-CSFr) and GM-CSF (GM-CSFr), the levels of each receptor and CSF were measured in patients with basophilia (8), eosinophilia (14) and bacterial infection showing neutrophilia (12) in comparison with normal healthy adults (12) and children (14). G-CSFr was expressed in neutrophils in the largest amount followed by monocytes, but GM-CSFr was expressed more in monocytes than neutrophils. Lymphocytes and basophils did not express G-CSFr or GM-CSFr. The amount of GM-CSFr in neutrophils was present less in patients with infection than normal control (P = 0.031). The neutrophils expressed more G-CSFr than GM-CSFr. The quantity of G-CSFr in eosinophil showed marked interval change, higher in acute stage. The plasma concentrations of G-CSF in patients with infection were much higher than normal adults or children (117.95 +/- 181.16 pg/ml, P < 0.05). Binding assay with excess amount of CSFs could discriminate the patient who did not show any response to G-CSF or GM-CSF administration. After incubation with excess CSFs, more receptors were blocked in children than in adults (G-CSF P = 0.024, GM-CSF P = 0.006). These results indicate that the amount of CSFr in leukocyte varies in different types of leukocyte, and changes according to the patients' condition even in the same type of leukocyte, and the CSFrs of children bind to CSFs more than those of adults.

Controlled growth factor release from synthetic extracellular matrices

Polymeric matrices can be used to grow new tissues and organs, and the delivery of growth factors from these matrices is one method to regenerate tissues. A problem with engineering tissues that exist in a mechanically dynamic environment, such as bone, muscle and blood vessels, is that most drug delivery systems have been designed to operate under static conditions. We thought that polymeric matrices, which release growth factors in response to mechanical signals, might provide a new approach to guide tissue formation in mechanically stressed environments. Critical design features for this type of system include the ability to undergo repeated deformation, and a reversible binding of the protein growth factors to polymeric matrices to allow for responses to repeated stimuli. Here we report a model delivery system that can respond to mechanical signalling and upregulate the release of a growth factor to promote blood vessel formation. This approach may find a number of applications, including regeneration and engineering of new tissues and more general drug-delivery applications.

Facile and efficient total synthesis of (+)-preussin

[structure] The enantioselective total synthesis of (+)-preussin, a potent antifungal agent, has been achieved. The key steps are a Pd(0)-catalyzed oxazoline-forming reaction from L-phenylalanine, hydrogenolysis, and subsequent diastereoselective reductive cyclization of the intermediate aminoketone to pyrrolidine using Pearlman's catalyst.

Identification and characterization of the major allergens of buckwheat

BACKGROUND

Buckwheat (BW) has been recognized as a common food allergen in Korea, Japan, and other countries. Until now, serologic findings of BW food-allergic patients and its major allergenic components have not been clarified. In this study, we analyzed the serologic findings of BW food allergy and characterized its major allergenic components.

METHODS

Nineteen BW-allergic subjects with symptoms after BW ingestion and 15 asymptomatic control subjects with positive skin prick test to BW were recruited. BW-specific IgE was measured with the Pharmacia CAP kit. Allergenic components of BW were analyzed by IgE immunoblotting, periodate oxidation, two-dimensonal PAGE, and sequencing of N-terminal amino acids.

RESULTS

From the BW-allergic patients and asymptomatic controls, the sensitivity (100%), specificity (53%), and negative (100%) and positive predictive values (73%) of Pharmacia CAP specific IgE for diagnosis were estimated. The prevalence of IgE binding to 24-kDa (pI 8.3), 16-kDa (pI 5.6), and 9-kDa (pI 5.0/ 6.0) allergens was higher than 50% in BW-allergic and asymptomatic subjects. However, the specific IgE to split 19-kDa (pI 6.5/7.0) allergens were more specifically found in BW-allergic patients than in asymptomatic subjects (78% vs 7%). N-terminal amino-acid sequences of 19-kDa and 16-kDa allergens showed moderate and weak homology to the 19-kDa globulin protein of rice and alpha-amylase/trypsin inhibitor of millet, respectively. The N-terminus of the 9-kDa isoallergens were not different from each other and were identified as the reported trypsin inhibitors of BW. Attenuation of the IgE binding to the 9-kDa allergen was found with periodate oxidation.

CONCLUSIONS

The allergens of 24, 19, 16, and 9 kDa are strong candidates to be major allergens, and the 19-kDa allergen was relatively specific for BW-allergic patients. Moreover, measurement of BW-specific IgE and the features of immunoblotting should be very useful tools in the diagnosis of BW allergy.

Prevalence of gynecologic cancers among female Vietnam veterans

The possibility of a gender-specific health problem associated with the Vietnam War has been a concern since the war. We targeted 4140 female Vietnam veterans and 4140 veteran controls to complete a structured telephone interview that included questions regarding any history of gynecologic cancer. As a measure of association between the risk of cancer and military service in Vietnam, odds ratios and 95% confidence intervals were calculated using multiple logistic regression models that yielded estimates of potential cofounders. Although 8% of Vietnam veterans and 7.1% of non-Vietnam veterans reported a history of gynecologic cancers, namely, breast, ovary, uterus, or cervix, the difference was not statistically significant either for the individual site or for the gynecologic cancers as a group. Female Vietnam veterans have not experienced a higher prevalence of gynecologic cancer in the 30 years since the conflict.

Effects of prednisolone on eosinophils, IL-5, eosinophil cationic protein, EG2+ eosinophils, and nitric oxide metabolites in the sputum of patients with exacerbated asthma

Corticosteroids are considered to be one of the most effective medicine for asthma by suppressing airway inflammation. This study was carried out to investigate the effects of prednisolone in the sputum of exacerbated asthmatics. Clinical severity, cell differentials, levels of interleukin (IL)-5, eosinophil cationic protein (ECP), EG2+ eosinophils, and nitric oxide (NO) metabolites were measured. Sputum was examined 2 weeks apart in 13 exacerbated asthmatics before and after prednisolone treatment, and once in 12 stable asthmatics. We used a sandwich ELISA for IL-5, fluoroimmunoassay for ECP, immunohistochemical staining for EG2+ eosinophils, a NO metabolites assay using modified Griess reaction. Exacerbated asthmatics, in comparison with stable asthmatics, had significantly higher proportion of eosinophils, higher level of ECP, higher percentage of EG2+ eosinophils, and NO metabolites. Exacerbated asthmatics after treatment with prednisolone had reduced the proportions of eosinophils, reduced level of IL-5, ECP and percentage of EG2+ eosinophils. FEV1 was correlated with the proportion of eosinophils, ECP, and IL-5 respectively. These findings suggest that prednisolone is considered to be effective medicine for asthma by suppressing eosinophil activation through IL-5.

Pregnancy outcomes among U.S. women Vietnam veterans

BACKGROUND

Since the 1965-1975 Vietnam War, there has been persistent concern that women who served in the U.S. military in Vietnam may have experienced adverse pregnancy outcomes.

METHODS

We compared self-reported pregnancy outcomes for 4,140 women Vietnam veterans with those of 4,140 contemporary women veterans who were not deployed to Vietnam. As a measure of association, we calculated odds ratios (OR) and 95% confidence intervals (CI) using logistic regression adjusting for age at conception, race, education, military nursing status, smoking, drinking and other exposures during pregnancy.

RESULTS

There was no statistically significant association between military service in Vietnam and index pregnancies resulting in miscarriage or stillbirth, low birth weight, pre-term delivery, or infant death. The risk of having children with "moderate-to-severe" birth defects was significantly elevated among Vietnam veterans (adjusted OR = 1.46, 95% CI = 1.06-2.02).

CONCLUSIONS

The risk of birth defects among index children was significantly associated with mother's military service in Vietnam.

Purification of dual-tagged intact recombinant proteins

Large-scale purification of recombinant proteins has been used extensively to assist numerous protein studies, including investigation of function, substrate identification and protein-protein interaction of low abundance proteins. Genetic fusion of affinity tags to these proteins has also been widely used for ease of purification by affinity chromatography. However, this technique sometimes yields unstable and degraded protein products limiting its application. In this study, we show a facile and straightforward method of dual-tagged recombinant protein purification that eliminates contamination by degraded protein products. A 6His-containing BamHI-HindIII fragment from pQE12 was ligated into the pGEX-KG BamHI-HindIII fragment and the protein of interest (p25(nck5a), which is highly susceptible to proteolytic degradation when expressed and purified from bacteria) was cloned into the BamHI site without a termination codon. The resulting plasmid construct, designated as pGST-p25(nck5a)-6His, with GST at the N-terminal and 6His at the C-terminal was expressed in Escherichia coli DH5alpha and purified using a two-step procedure. We show that using Ni(2+)-NTA chromatography as a first purification step and GSH-agarose chromatography as a second step, rather than vice-versa, yields a highly purified intact protein that is free of any contaminating degraded protein product. The purified fusion protein is soluble and fully active.

The expression of cytokeratin 18 in transitional cell carcinoma comparing with hepatoma

The epithelium in kidneys and urinary bladders contain CK18 as in liver cells. The modulation of cytokeratin 18 during tumor transformation in hepatoma had been previously recognized through a series of biochemical and immunological approaches. A 14 KD hepatoma related molecules was found in the previous studies. We would like to utilize the hepatoma transformation model to study the changes in CK18 in transitional cell carcinoma, using immunoblotting and western blotting techniques. The result is that transitional cell carcinoma retain their CK18 molecule. Furthermore, CK18 related molecules similar to those seen in hepatoma also present in transitional cell carcinoma. The conclusions are transitional cell carcinoma contains CK18 related proteins similar to those seen in hepatoma tissues. We suggest that this element would be responsible for the change during the malignant transformation processes.

Stabilizing of cytokeratin in PLC/PRF/5 cells

There are two sorted groups of cytokeratin 18 (CK18) in forms of assembly and disassembly in PLC/PRF/5 cells. A subcellular shifting is found in association with conditions of microtubule networks. The finding shows that CK18 mostly in forms of assembly, when microtubule networks are in status. The result also reveals that CK18 is relatively in forms of disassembly, while microtubule networks are disrupted in steps. It indicates that intact microtubule networks are probably a stabilizing factor of assembled CK18. It implies that CK18 is not a stable molecule when the cell is under environmental stress.

Sustained and controlled release of daunomycin from cross-linked poly(aldehyde guluronate) hydrogels

We have incorporated daunomycin, an antineoplastic agent, into a biodegradable hydrogel through a labile covalent bond. In brief, sodium alginate was chemically broken down to low molecular weight and followed by oxidation to prepare poly(aldehyde guluronate). Adipic dihydrazide was used to incorporate the drug into the polymer backbone and cross-link the polymer to form hydrogels. Daunomycin can be released from the hydrogel after the hydrolysis of the covalent linkage between the drug and the polymer. A wide range of release profiles of daunomycin (e.g., from 2 days to 6 weeks) has been achieved using these materials, and the biological activity of the released daunomycin was maintained.

Solubility changes in shelf-aged ultra-high molecular weight polyethylene acetabular liners

Crosslinking of extruded, air-packaged, irradiated, shelf-aged (10 consecutive years) polyethylene acetabular liners was measured versus time and material location by using a hot xylene extraction protocol. Insolubility (crosslinking) of new polyethylene liners was 87%, but decreased to 45% after 10 years of shelf-aging. This degradation is similar to that observed from retrieved (aged in vivo) acetabular cups. Crosslinking varied with depth in the aged liners and with radial location in the unaged liners. Given that crosslinking improves polyethylene's wear resistance, crosslinking degradation of polyethylene orthopaedic components must be controlled to improve the long-term clinical performance of total joint implants.

Activated phenoloxidase from Tenebrio molitor larvae enhances the synthesis of melanin by using a vitellogenin-like protein in the presence of dopamine

One of the biological functions of activated phenoloxidase in arthropods is the synthesis of melanin around invaded foreign materials. However, little is known about how activated phenoloxidase synthesizes melanin at the molecular level. Even though it has been suggested that the quinone derivatives generated by activated phenoloxidase might use endogenous protein components for melanin synthesis in arthropods, there is no report of protein components engaged in melanin synthesis induced by activated phenoloxidase. In this study, to isolate and characterize proteins involved in melanin synthesis, we prepared in vitro prophenoloxidase activating solution (designated G-100 solution), specifically showing phenoloxidase activity in the presence of Ca2+ and beta-1, 3-glucan, from the hemolymph of larvae of the coleopteran Tenebrio molitor by using a Sephadex G-100 column. When G-100 solution was incubated with dopamine to induce melanin synthesis in the presence of Ca2+ and beta-1,3-glucan, four types of protein (160 kDa, prophenoloxidase, phenoloxidase and 45 kDa) disappeared from SDS/PAGE under reducing conditions. Under identical conditions, but including phenylthiourea as a phenoloxidase inhibitor added to the G-100 solution, three of these proteins (160 kDa, phenoloxidase and 45 kDa) did not disappear. To characterize these melanization-engaging proteins, we first purified the 160-kDa melanization-engaging protein to homogeneity and raised a polyclonal antibody against it. Analysis of the cDNA revealed that it consisted of 1439 amino-acid residues and showed partial homology with Caenorhabditis elegans vitellogenin precursor-6 (19.7%). Western blot analysis showed that it disappeared when active phenoloxidase induced melanin synthesis. Furthermore, when the purified 160-kDa melanization-engaging protein was added to a G-100 solution deficient in it, melanin synthesis was enhanced compared with the same solution without the protein. These data support the conclusion that the 160-kDa vitellogenin-like protein is involved in arthropod melanin synthesis.

Acute respiratory distress syndrome associated with scrub typhus: diffuse alveolar damage without pulmonary vasculitis

Pathologic findings of scrub typhus have been characterized by vasculitis of the microvasculature of the involved organ resulting from a direct invasion by Orientia tsutsugamushi. We experienced a case of acute respiratory distress syndrome (ARDS) associated with scrub typhus. The case was proven by eschar and high titer of serum IgM antibody (positive at 1:1280). Open lung biopsy showed diffuse alveolar damage (DAD) in the organizing stage without evidence of vasculitis. Immunofluorescent antibody staining and polymerase chain reaction for O. tsutsugamushi failed to demonstrate the organism in the lung tissue. The patient expired due to progressive respiratory failure despite doxycycline therapy. Immunologic mechanism, without direct invasion of the organism, may participate in the pathogenesis of ARDS associated with scrub typhus.

Basilar artery vasospasm in postpartum cerebral angiopathy

The reason cerebral edema in postpartum cerebral angiopathy (PPCA) occurs preferentially in the posterior brain is poorly understood. The authors present two patients with PPCA who showed vasospasm occurring earlier and more severely in the basilar artery than in the middle cerebral artery. Our patients demonstrate the difference in vascular change between the anterior and posterior cerebral vessels, explaining the susceptibility of the posterior brain to PPCA.

Novel induction of alpha-lactalbumin-mediated lacdiNAc-R expression in vivo

alpha-Lactalbumin (alpha-LA) is a regulatory protein by which the mammalian beta1,4-galactosyltransferase (beta1,4-galT) is induced to utilize glucose as an acceptor instead of N-acetylglucosamine (GlcNAc) during lactose synthesis in mammary gland. alpha-LA can also modulate beta1,4-galT to utilize UDP-N-acetylgalactosamine (UDP-GalNAc) as a donor towards GlcNAc acceptor substrate with high efficiency in vitro [Do, Do and Cummings (1995) J. Biol. Chem. 270, 18447-18451]. In the present study we transfected cDNA encoding bovine alpha-LA into Lec8 cells and examined whether nucleotide sugar switching of UDP-galactose (UDP-Gal) into UDP-GalNAc occurred in vivo and whether the neo-glycosylation of GalNAcbeta1,4GlcNAc-R structure was synthesized in alpha-LA-stable transfectants. Our studies demonstrate that the stable expression of alpha-LA in Lec8 cells induces the formation of GalNAcbeta1,4GlcNAc-R in vivo through the nucleotide sugar switching of beta1,4-galT.

Two-spotted spider mite (Tetranychus urticae): an important allergen in asthmatic non-farmers symtomatic in summer and fall months

BACKGROUND

The Tetranychus urticae (two-spotted spider mite, TSM) is a spider mite commonly found on fruit trees, herbaceous plants, and greenhouse flowers.

OBJECTIVE

To evaluate the clinical significance of TSM-derived allergens in non-farmers with asthma living around pear orchards, and to assess the allergenic relationship with house dust mite.

METHODS

Skin prick tests with TSM were performed in 50 asthmatic non-farmers living around pear orchards. The serum TSM-specific IgE was measured in the 16 asthmatics with a positive skin response to TSM. To diagnose TSM-induced asthma, specific bronchial challenges with TSM were performed in the 16 asthmatics. ELISA inhibition tests were performed to assess the allergenic cross-reactivity with house dust mites.

RESULTS

Ten of the 16 asthmatics with positive skin responses to TSM showed a significant bronchoconstriction following inhalation of TSM. Eight of the ten TSM-induced asthmatics had high serum TSM-specific IgE and one showed a positive skin response only to TSM. Their asthmatic symptoms were aggravated seasonally, especially in summer and early fall. On ELISA inhibition tests, partial inhibitions with D. pteronyssinus antigens were noted in sera from five asthmatics with positive skin responses to both TSM and D. pteronyssinus, although no inhibition was noted in serum from an asthmatic with a positive skin response only to TSM.

CONCLUSION

Tetranychus urticae may be an important allergen in asthmatic non-farmers living around pear orchards and TSM extracts contain species-specific allergens as well as commonly shared allergens with house dust mite.

Illnesses among United States veterans of the Gulf War: a population-based survey of 30,000 veterans

Despite numerous studies on veterans of the 1990 to 1991 Gulf War, the fundamental questions of how healthy they are and how their health compares with that of their military peers who were not deployed to the Gulf have not been fully answered. We conducted a health survey in which the health outcomes of a population-based sample of 15,000 Gulf veterans representing various military branches and unit components (regular, reserve, National Guard) were compared with those of 15,000 non-Gulf veterans who were randomly sampled to mirror the number in the same military strata in the Gulf veteran group. In comparison with their peers, Gulf veterans had a higher prevalence of functional impairment, health care utilization, symptoms, and medical conditions and a higher rate of low general health perceptions. A longitudinal follow-up of the health of these veterans will be needed to detect changes in health status and to detect diseases with a long latency period.

Pilot study of IFN-gamma-induced specific hyposensitization for house dust mites in atopic dermatitis: IFN-gamma-induced immune deviation as a new therapeutic concept for atopic dermatitis

IFN-gamma/IL-4 imbalance is a central immunologic defect which is responsible for increased IgE antibody response in atopic dermatitis. Effects of hyposensitization were controversial in atopic dermatitis. Reversed IFN-gamma/IL-4 balance was induced using IFN-gamma in atopic dermatitis and specific hyposensitization with house dust mites (HDM) was tried in the status of IFN-gamma-induced immune deviation. A total of 58 atopic dermatitis patients who had obvious allergy to HDM were selected in this study. IFN-gamma-induced hyposensitization for HDM was tried in 10 patients. Twenty-two patients received IFN-gamma therapy and six were treated by simple hyposensitization. Twenty were enrolled as control subjects. The clinical severity scores decreased effectively only by IFN-gamma-induced hyposensitization for HDM. Specific hyposensitization for HDM in the status of IFN-gamma-induced immune deviation successfully improved atopic dermatitis. HDM might play a pathogenic role in subpopulation of atopic dermatitis.

Factors influencing vascular and hepatic enhancement at CT: experimental study on injection protocol using a canine model

PURPOSE

The purpose of this work was to evaluate the effects of contrast medium injection parameters on aortic, portal vein, and hepatic enhancement at spiral CT and to assess optimal injection protocol for hepatic CT.

METHOD

Ten 15 kg dogs underwent single level dynamic CT through the hepatic hilum at 5 s intervals just after the injection of contrast medium for 3 min. With use of different volumes (1, 2, and 3 ml/kg), injection rates (0.5, 1, and 2 ml/s), and concentrations (150, 200, and 300 mg/ml), a total of 270 spiral CT scans were performed. In each scan, time-attenuation curves of aorta, portal vein, and liver were obtained. The degree of maximum contrast enhancement (Imax), time to maximum enhancement (Tmax), and time to equilibrium phase (Teq) for to each injection protocol were analyzed.

RESULTS

Alterations in contrast material volume, injection rate, and concentration had significant impact on contrast enhancement of the liver. With increasing volume of contrast medium, Imax, Tmax, and Teq of aorta, portal vein, and liver increased (p < 0.005). With increasing rate of injection, on the other hand, Imax of aorta and liver increased (p < 0.05), but Tmax and Teq decreased (p < 0.005). Change of concentration of contrast medium had a significant effect on Imax of vessels (p < 0.05).

CONCLUSION

Maximum contrast enhancement of liver and vessels was influenced mainly by injection volume of contrast medium and the time to peak enhancement by injection rate of contrast medium. Under given amounts of contrast medium, therefore, the strategy of increasing volume by dilution and faster injection might give better Imax values without penalty for the duration of an optimal temporal window (Tmax and Teq).