Intraoperative monitoring with pulse Doppler ultrasonography in transsphenoidal surgery: technique application

We describe an intraoperative use of pulse Doppler ultrasonography in transsphenoidal surgery to prevent mechanical vascular injury, particularly to the intracavernous portion of the internal carotid artery. This system is integrated by connection to a video processor. The use of Doppler sonography provided real-time measurement of arterial or venous flow velocity and source of flow by both real-time sonograms and sound frequencies. With the use of a microprobe, 1 mm in diameter, vessels located within 7 mm from the tip of the probe could be easily, rapidly, and noninvasively detected, without disturbing operative field. Furthermore, both the size and the distance of a vessel could be measured by turning the dial of Doppler signal gain from initially waxing to waning Doppler sounds, because the acoustic sounds were adjusted to the axial flow of each vessel in 0.1-mm increments. Our intraoperative monitoring enhanced operative safety with technical simplicity and reliability.

Explorations into development of a neurally regulated cardiac pacemaker

Although the artificial cardiac pacemaker has contributed to the management of patients with serious arrhythmias, its rate-responsive function is not sufficient to provide physiological regulation of heart rate (HR). To achieve truly physiological rate response in any given patient, we propose a framework to develop a pacemaker directly regulated by sympathetic nerve activity (SNA). In eight anesthetized rabbits, we quantified the dynamic transduction characteristics from SNA to HR as a transfer function. We then characterized the decoding rule as an impulse response, that is the transfer characteristics in the time domain. The transfer function was approximated by a first-order, low-pass filter with lag time (corner frequency: 0.024 +/- 0.013 Hz, lag time: 0.98 +/- 0.09 s). Predicted HR correlated well with measured HR (r = 0.80-0.98). The standard error of the prediction relative to mean HR was only 1.2 +/- 0.7%, indicating that the prediction was reasonably accurate. Direct decoding of SNA to predict instantaneous HR is possible through this analysis. This framework should enable development of a neurally regulated artificial pacemaker.

[Relation of life style, working posture and job category to body mass index change in young male workers]

The relationships of change in body mass index (BMI) on blood pressure, blood and serum tests, and of life style, working posture and job category on change in BMI after age twenty were investigated in a cross sectional study. A total of 771 male employees aged 21 or older (mean age 29.9 +/- 9.1 years) of a semiconductor factory were examined in December 1993. BMI change of each subject was expressed as percent increase after age twenty. BMI value at age twenty was calculated from self-reported body weight at twenty and height measured at the 1993 health examination. Prevalences of high blood pressure (systolic blood pressure > or = 160 mmHg or diastolic blood pressure > or = 95 mmHg), high blood pressure including borderline hypertension (systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg) and abnormal values of serum GOT, GPT, gamma-GPT, total cholesterol, triglyceride, HDL-cholesterol, uric acid and fasting blood glucose were greater in the high BMI change group than in the low BMI change group (Chi-square test, P < 0.1). With the exception of hypertension, these associations remained virtually unchanged after adjusting for age, alcoholic consumption, smoking habits and BMI at 20 years of age by multiple logistic regression analysis. After adjustment for age by the Mantel-Henszael method, increases in BMI after 20 years of age were positively associated with the following eight items (p < 0.05): shorter standing time, shorter walking time, lower meal skipping frequency, shorter meal time, longer sitting time during work, larger meal size, greater frequency of salad consumption, and sedentary work such as clerk and engineer. Greater rice consumption and higher frequency of instant foods consumption were weakly associated with the increase in BMI (0.05 < p < 0.1). Job categories such as clerk and engineer were significantly associated with longer sitting time and shorter meal time, resulting in greater BMI increase after 20 years of age. Multiple logistic regression analysis revealed that shorter standing time, shorter meal time, larger meal size, greater frequency of instant foods consumption and greater frequency of salad consumption were independently correlated with the increase in BMI (p < 0.05). Larger rice consumption was slightly correlated with increasing BMI (0.05 < p < 0.1). This study showed that job category, working posture and food intake patterns were strongly associated with BMI change after age 20 in young male workers. This study provides useful information for health care and health promotion programs in young male workers.

Somatostatin inhibits cholecystokinin-induced contraction of isolated gallbladder smooth muscle cells

A close relation between the hyperhormonism of somatostatin and gallstone disease suggested to us the hypothesis that somatostatin inhibits cholecystokinin (CCK)-induced gallbladder contraction on the level of target organs. To investigate this hypothesis, smooth muscle cells were isolated from human and canine gallbladders and the direct inhibitory effects of somatostatin on the CCK-induced cell contraction were examined in vitro. Somatostatin alone had no effect on the cell motility, while it significantly inhibited the cholecystokinin-octapeptide (10(-10) M)-induced cell contraction at the concentration of 10(-6) M (P < 0.01) in both human and canine gallbladders. The results demonstrate for the first time that somatostatin has a direct inhibitory action against cholecystokinin-induced gallbladder contraction. This may partly account for the high frequency of gallstone disease in patients with somatostatinoma.

[Intratumoral pharmacokinetics following intraarterial administration of MCNU in patients with malignant gliomas]

This clinical study was undertaken to examine intratumoral (i.t.) pharmacokinetics after intraarterial (i.a.) administration of MCNU (80mg/m2) in 5 patients with glioblastoma (GB) and 2 with anaplastic astrocytoma (AA). After resection or stereotactic biopsy of the cystic lesion, an Ommaya reservoir was placed into the tumor cavity in all patients. The distribution of MCNU in blood was compatible with a two-compartment model, and the half life of the alpha-phase and beta-phase was 4.1 minutes and 160.4 minutes, respectively. MCNU was detected in the i.t. fluid in 5 cases, 4 of GB and 1 of AA. The concentration of i.t. MCNU gradually increased during the 5 to 30 minutes after i.a. injection to a level about 20.0% of its blood concentration. However, no MCNU was detected in patients showing partial response (3 of GB and 1 of AA) or no change (1 of GB) after the i.a. infusion of MCNU during maintenance chemotherapy. These results suggests that MCNU may transfer into the tumor tissues. Further investigation is warranted.

[Effects of the nitric oxide donor SIN-1 on the membrane potential of mouse neuroblastoma-rat glioma hybrid cells]

The effect of the nitric oxide donor SIN-1 on the membrane potential of cultured mouse neuroblastoma-rat glioma hybrid NG108-15 cells was investigated using the whole cell patch method. It has been reported that neurite formation can be induced in NG108-15 cells by adding of dibutyryl cyclic AMP to the culture medium. Using this system we found that SIN-1 has a selective inhibitory effect on the membrane potential of the calcium current which is concentration-dependent in the 1 mu M-100 microM range. This effect was transient and reversible, the same as seen with the calcium channel blocker nilvadipine at concentrations of 10 microM to 10 microM. At higher concentrations, ranging from 500 microM to 1 mM, however, SIN-1 also caused prolonged inhibition of the membrane potential of the sodium current. However, this effect was also reversible. These findings suggest that SIN-1 has a reversible inhibitory action on the membrane potentials of neurons.

[The efficacy of granisetron as a prophylactic anti-emetic agent used in conjunction with MCNU and VP16 chemotherapeutic regimens in the management of a pediatric case of hypothalamic anaplastic astrocytoma]

The management of a 12-year-old boy with hypothalamic anaplastic astrocytoma is reported herein. The pediatric patient underwent a subtotal removal of his brain tumor, and subsequently received multimodal treatment comprising radiotherapy (30.6 Gy to the whole brain and 50.4 Gy to the local lesion) and immunochemotherapy with MCNU (80 mg/m2, day 1), VP 16 (50 mg/day, days 2 to 6), and interferon-beta (3 x 10(6) units/day, initiating on day 2 for 4 weeks). The immunochemotherapy was given as of 4 weeks after radiotherapy. The administration of anti-cancer drugs caused severe nausea and vomiting, the intra-carotid infusion of MCNU being particularly emetogenic. The multi-modal treatment was then discontinued for a few weeks. A partial response was obtained, and the patient subsequently received 3 courses of maintenance therapy at six-month intervals using the same protocol as for the initial immunochemotherapy. During maintenance therapy, granisetron (40 micrograms/kg) was given intravenously 30 minutes before and one day after the injection of MCNU. Owing to the anti-emetic management of this patient, there were no complications throughout the chemotherapy. The patient has now survived for more than 3 years with a good quality of life, showing a Karnofsky performance score of 90.

Primary malignant lymphoma of the central nervous system--report of four long-term survivors

Four of 47 patients treated between 1977 and 1993 for histologically confirmed primary malignant lymphoma of the central nervous system (non-Hodgkin's type of B-cell origin) achieved long-term survival for more than 5 years with a good quality of life. Three have remained disease-free for 9-12.5 years. The fourth achieved complete remission for more than 5 years before death from tumor recurrence. All four patients were treated with a standard therapeutic regimen, consisting of radiotherapy (50-60 Gy local and 30-40 Gy whole brain irradiation) followed by four to six courses of chemotherapy with cyclophosphamide, vincristine, adriamycin, and prednisolone at 4- to 8-week intervals. No further treatment was performed after remission had been obtained. No specific predictors for long-term survival including sex, age, tumor location, multiplicity of lesions, histology, or treatment modality was identified. All four patients showed an immediate tumor response to radiation. We recommend chemotherapy at increasing intervals as part of the post-therapeutic management of long-term, disease-free patients.

[Glial tumor cell proliferation and immune response in the brain]

The mechanism of glial tumor cell proliferation and the immune response to glioma cells in the brain were examined both in vitro and in vivo experimental systems, using mouse malignant glioma cell line, 203-glioma. A fura-2 fluorescence image showed marked rise in the intracellular calcium ion concentration in mechanically stimulated single cells. The increased calcium spread to adjacent cells, probably due to some stimulating factor released from cells. Dye microinjection revealed no gap junction between cells. Antagonists of voltage-dependent calcium channels did not act on the calcium response. These suggest that calcium signaling in the glioma cells may be mediated via a membrane receptor but not through a gap junction. Depletion of extracellular calcium ion and addition of intracellular calcium blocker demonstrated that calcium signaling in stimulated cells may be related to both an influx of extracellular calcium and a redistribution of intracellular calcium from internal stores, whereas calcium transmission to adjacent cells may involve calcium influx alone. The splenic cytotoxic T lymphocyte (CTL) activity in intracerebral tumor-bearing hosts increased with a peak 2 weeks after tumor cell inoculation, but rapidly decreased concurrently with increased intracranial pressure. The major histocompatibility complex, MHC, class I antigen expression on tumor cells grafted intracerebrally was found to enhance markedly, resulting in an increase in susceptibility to CTL. It was suggested that there may be a positive correlation between the cell surface MHC class I antigen expression and sensitivity to CTL in glioma cells.

[Detection and quantitation of cytomegalovirus DNA in plasma from patients with cytomegalovirus pneumonia]

Detection and semiquantitation of cytomegalovirus (CMV) DNA in plasma from 17 immunocompromised patients with CMV pneumonia diagnosed histopathologically, 15 CMV seropositive patients without CMV pneumonia and 24 CMV-seropositive healthy volunteers were evaluated, using the polymerase chain reaction (PCR). CMV DNA was detected in plasma from all of 17 patients with CMV pneumonia, from 1 of 15 patients without CMV disease, but from none of healthy volunteers. One patient without CMV disease exhibited positive CMV DNA by PCR 2 days before death. Plasma CMV DNA was negative at the time of admission in all patients, however, it became positive 1-28 days (mean, 14 days) before the onset of CMV pneumonia in 16 patients. The amount of viral DNA in plasma were 10(3) - 10(5) copies/ml (mean, 10 (4.0) copies/ml) when first detected by PCR. At the onset of CMV pneumonia, they were 10(4)-10(6)(mean, 10(5.3) copies/ml), and increased with disease progression and decreased with disease improvement because of treatment with antiviral agents. We succeeded in detection of CMV DNA in plasma before the development of CMV pneumonia, and showed the amount of viral DNA reflected the extent of active CMV pneumonia. Thus, PCR amplification of CMV DNA in plasma is a useful tool for early diagnosis and monitoring of immunocompromised patients.

Interleukin-2 receptor positive T and B cells in children with acute severe asthmatic attack

Subpopulations of interleukin-2 receptor (IL-2R)-positive CD4 and CD8 T cells and IL-2R+CD20 B cells in the peripheral blood lymphocytes as well as serum concentrations of soluble IL-2R (sIL2R) were measured in children aged 1-7 years who suffered acute severe asthmatic attack. Subpopulations of CD4+IL-2R+ cells, CD8+IL-2R+ cells and CD20+IL-2R+ cells in the peripheral blood lymphocytes at acute severe asthmatic attack phase were significantly higher than those at non-asthmatic attack phase (P < 0.02, P < 0.03 and P < 0.02, respectively). Subpopulations of CD20+IL-2R+ cells in the peripheral blood lymphocytes significantly decreased 5-10 days after acute severe asthmatic attack (at recovery phase, P < 0.02) and were significantly correlated with clinical severity of asthmatic attack (P < 0.05). These results indicated that activation of both T cells and B cells was important in the pathogenesis of acute asthmatic attack in young children.

[Microbiological and clinical study of fungemia between 1981 and 1992]

Fungi were isolated from 113 (14.2%) of 789 patients with positive blood cultures at Oita Medical University Hospital between 1981 and 1992. The rates of fungemia increased in recent years, 13.9% (1981-1985), 12.1% (1986-1988) and 16.9% (1989-1992). The isolated fungi were Candida parapsilosis (25.7%), C. albicans (24.8%), C. tropicalis (14.2%), Trichosporon beigelii (10.6%), C. glabrata (8.0%) and so on. The major fungi were T. beigelii and C. glabrata in patients with hematologic malignancies, whereas they were C. albicans and C. parapsilosis in patients with non-hematologic diseases and C. glabrata increased in both groups. Prophylactic or emiric administration of antifungal agents probably influenced the difference of the causative organisms in the two groups.

Measurements of thoron progeny concentration using a potential alpha-energy monitor in Japan

It is reported that thoron concentration in Japanese dwellings may be higher than in other dwellings. Therefore, in order to assess the risk for indoor thoron progeny, the portable potential alpha-energy monitor has been developed. The monitor detects alpha-particles from the 212Po collected on the filter using a piece of cellulose nitrate film. The detection efficiency of the alpha-particles has been estimated by Monte Carlo calculation. From the results of measurements, the mean indoor thoron progeny concentration in the dwellings was 1.5 Bq m-3 (ECTn), and ranged from 0.04 to 8.2 Bq m-3. The effects of three typical interior walls (soil-based plaster, concrete, and modern materials) on the thoron progeny supply were considered. The mean annual effective dose equivalent was 0.45 mSv.

[Role of nitric oxide produced by activated macrophages in their cytocidal activity against glial tumor cells]

This study investigated the role of activated macrophages (M phi) in nitric oxide (NO) production and the tumoricidal effect of NO on glioma cells. Induced peritoneal M phi were prepared 6 days following the injection of thioglycollate broth into C3H/He N (H-2 kappa) mice. M phi were activated in vitro recombinant human interferon-gamma (IFN gamma) and lipopolysaccharide (LPS) into the culture medium of the elicited M phi. Two kinds of murine malignant glioma cell lines, RSV-M glioma (H-2 kappa) and VM-glioma (H-2b) were used as targets. P815 mastocytoma cells (H-2d) were used as a control target, since they are insensitive to tumor necrosis factor-alpha, but susceptible to NO derived from M phi. L-arginine-depleted medium was used to inhibit NO-mediated cytocidal activity against tumor cells. Cytotoxicity was assayed at various effector-to-target ratios using an admixture of M phi and 1.5 x 10(4) 125I-labeled target cells 48 hours following co-culture. NO was measured in culture medium using Griess reagent, and the concentration of NO was expressed as mu mol/ml NaNO2. Peritoneal M phi induced only 10% and 15% lysis of RSV-M glioma and VM glioma cells, respective, and LPS augmented this killing activity of M phi to a maximum of 1.2 to 1.4 fold in a dose-dependent manner with dosages from 1 to 50 ng/ml. LPS demonstrated a synergistic action on M phi-mediated cytotoxicity 4 hours following pretreatment with IFN gamma. Alternatively, low doses of IFN gamma alone had no enhancing effect on M phi tumoricidal activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-CD40 monoclonal antibody induces the proliferation of murine B cells as a B-cell mitogen through a distinct pathway from receptors for antigens or lipopolysaccharide

To study the activation and differentiation of murine B cells, we prepared a hybridoma secreting monoclonal antibody, LB429, which can directly induce the proliferation of murine B cells in vitro. LB429 recognizes a B cell specific surface molecule of 45 kDa. It recognizes an epitope of murine CD40 produced as a soluble fusion protein with glutathione S-transferase. LB429 stains COS-7 transfectant with murine CD40 cDNA and mature B-cell lines but does not stain pre-B cell lines. Two color staining demonstrated that the epitope recognized with LB429 appears on the surface of B220+ cells of spleen and bone marrow. LB429 can induce a strong proliferation of murine B cells from spleen in the absence of initial triggering with anti-IgM antibody or with anti-IgM antibody + IL-4. LB429 induced the cell size enlargement and the cell cycle transition of resting B cells as well as lipopolysaccharide (LPS). LB429 and LPS stimulate B cells synergistically in vitro by accumulating 44.7% of cells in S/G2/M phases of cell cycle. However, stimulation of spleen B cells with LB429 resulted in the increase of sIgM high+ sIgD(high)+ B cells, in contrast LPS showed the proliferation of both sIgM(high)+ sIgD(high)+ B cells and sIgM(low)+ sIgD(high)+ B cells. These results suggested that LB429 and LPS cause the proliferation of B cells through different stimulatory pathways. This anti-mouse CD40 antibody (LB429) is a very useful reagent to study the activation and differentiation of B cells in vitro.

Hepatic nuclear factor 3- and hormone-regulated expression of the phosphoenolpyruvate carboxykinase and insulin-like growth factor-binding protein 1 genes

The rate of transcription of the hepatic phosphoenolpyruvate carboxykinase (PEPCK) and insulin-like growth factor-binding protein 1 (IGFBP-1) genes is stimulated by glucocorticoids and inhibited by insulin. In both cases, the effect of insulin is dominant, since it suppresses both basal and glucocorticoid-stimulated PEPCK or IGFBP-1 gene transcription. Analyses of both promoters by transfection of PEPCK or IGFBP-1-chloramphenicol acetyltransferase fusion genes into rat hepatoma cells has led to the identification of insulin response sequences (IRSs) in both genes. The core IRS, T(G/A)TTTTG, is the same in both genes, but the PEPCK promoter has a single copy of this element whereas the IGFBP-1 promoter has two copies arranged as an inverted palindrome. The IGFBP-1 IRS and PEPCK IRS both bind the alpha and beta forms of hepatic nuclear factor 3 (HNF-3), although the latter does so with a sixfold-lower relative affinity. Both the PEPCK and the IGFBP-1 IRSs also function as accessory factor binding sites required for the full induction of gene transcription by glucocorticoids. A combination of transient transfection and DNA binding studies suggests that HNF-3 is the accessory factor that supports glucocorticoid-induced gene transcription. In both genes, the HNF-3 binding site overlaps the IRS core motif(s). A model in which insulin is postulated to mediate its negative effect on glucocorticoid-induced PEPCK and IGFBP-1 gene transcription indirectly by inhibiting HNF-3 action is proposed.

Measurement of arterial tracer concentrations from cardiac PET images

OBJECTIVE

Cardiac PET imaging offers the potential capability for the noninvasive measurement of arterial input function. This capability is somewhat limited, however, because of partial volume and spillover effects. The purpose of this study was to validate arterial tracer concentration measurements using PET images by assigning a region of interest (ROI) to the left ventricle, left atrium (LA), and ascending aorta.

MATERIALS AND METHODS

We selected [11C]CO and [13N]ammonia as tracers, because the activity of [11C]CO is primarily in the blood pool and that of [13N]ammonia primarily in myocardial tissue. Six [11C]CO and 11 [13N]ammonia PET scans were obtained in 17 subjects. Arterial tracer concentrations determined by PET were compared with those measured by well counting of arterial blood sampling obtained at the midpoint of each image acquisition.

RESULTS

Arterial tracer concentrations as determined by LA-PET imaging correlated closely with those measured by blood sampling (r = 0.996, slope = 1.00 for [11C]CO; r = 0.841, slope = 0.974 for [13N]ammonia). Partial volume and spillover effects were minimized by assigning an ROI to the LA.

CONCLUSION

Arterial tracer concentrations can be measured noninvasively with cardiac PET.

[Pharmacokinetics of intratumoral interferon-gamma activity following subcutaneous administration of recombinant interferon-gamma in a patient with metastatic brain tumor derived from renal cancer]

Pharmacokinetic studies of intratumoral interferon (IFN)-gamma activity were performed 1 week and 1 month after subcutaneous (s.c.) administration of recombinant IFN-gamma (specific activity = 1 x 10(7) units/mg protein) to a patient with metastatic brain tumor in the right occipital lobe derived from primary renal cancer. The patient, a 54-year-old man, underwent total removal of the lesion on April 10, 1991, with placement of an indwelling Ommaya Reservoir in the tumor cavity. The histological diagnosis was clear-cell carcinoma. His postoperative course was uneventful. Due to detection of a new ring-like enhancing mass in the right temporal lobe on serial CT examination on May 27, radiotherapy was discontinued immediately after delivery of a total dose of 30 Gy. Recombinant IFN-gamma was then administered s.c. at a dose of 3 x 10(6) units/day for 6 weeks, and induced a partial response. During IFN-gamma therapy, IFN-gamma activity in intratumoral fluid was measured 0 min, 30 min, 90 min and 6 hours after s.c. injection of IFN-gamma. The level of IFN activity was determined by an enzyme-linked immunosorbent assay. Intra-tumoral IFN-gamma activity gradually increased, and showed the highest of measured values at 6 hours after administration, while serum IFN activity decreased rapidly with a half-life of 30 min. The patient was discharged on July 30, but died from complications of aspiration pneumonia on September 2, 1991.

Phosphofructokinase deficiency: recent advances in molecular biology

Phosphofructokinase (PFK) plays a major role in glycolysis. Deficiency of PFK-M is characterized by muscle weakness due to fuel crisis in exercising muscles. To elucidate the gene defect of PFK-deficient patients, we have cloned and determined the complete structure and transcription mechanism of human PFK-M mRNA and gene. Molecular defects were investigated in three unrelated Japanese family cases. The first case was characterized by a point mutation at the donor site of intron 15 of the PFK-M gene. Cryptic splicing resulted in a 25 amino acid truncation in the patient's PFK-M. The second case possessed a point mutation at the donor site of intron 19, resulting in the skipping of exon 19 and the truncation of 55 amino acids. In the third case, a missense mutation was identified in the coding region. The review of an updated mutation repertoire indicates the heterogeneity of the molecular mechanism of the disease.

Hepatic resection for hepatolithiasis and long-term results

BACKGROUND

Hepatic resection is an established procedure for treating patients with hepatolithiasis. The long-term results after hepatic resection for hepatolithiasis were appraised.

STUDY DESIGN

Of 127 patients with hepatolithiasis seen between 1973 and 1993, 43 patients underwent hepatic resection, and constituted the basis of this study.

RESULTS

There was one operative death (operative mortality rate of 2.3 percent) and three deaths as a result of concomitantly associated cholangiocellular carcinoma. Of the remaining 39 patients, the complete stone clearance rate was 67 percent with operation alone, but reached 87 percent when cholangioscopy was used. Operative morbidity was recorded in five patients (12 percent), but they recovered with conservative therapy. Stones recurred in 15 percent of patients after a mean follow-up period of four years (range of three to six years). Eleven (28 percent) of 39 patients died after hepatectomy as a result of related diseases after a mean follow-up of 6.2 years. These 11 patients had associated biliary drainage procedures. They experienced a higher mortality rate (p < 0.05) than patients who did not have biliary drainage.

CONCLUSIONS

We conclude that hepatic resection is adequate treatment for hepatolithiasis. The patients having additional biliary drainage procedures had a higher mortality, but one cannot reach conclusions about the negative effect of the drainage procedures because the drainage procedures were done in a selected and not a randomized manner.

Potential convergence of insulin and cAMP signal transduction systems at the phosphoenolpyruvate carboxykinase (PEPCK) gene promoter through CCAAT/enhancer binding protein (C/EBP)

Adenosine 3',5'-monophosphate (cAMP) stimulates phosphoenolpyruvate carboxykinase (PEPCK) gene transcription, whereas insulin has the opposite effect. In H4IIE cells, the effect of insulin is dominant since it represses cAMP-stimulated transcription. Discrete cis-acting elements in the PEPCK promoter that serve as an insulin response sequence (IRS) and cAMP response element (CRE) have been identified. Here we show that common proteins can bind both elements, since: (i) an almost identical pattern of protein binding is seen when oligonucleotides representing either the IRS or the CRE are used as the labeled probe in a gel retardation assay and (ii) the unlabeled wild-type, but not mutated, CRE oligonucleotide competes for protein binding to the labeled IRS probe, and vice versa. Six homo- and heterodimer complexes interact with these DNA elements; the complexes are composed of three individual protein species: (a) 42-kDa C/EBP alpha, (b) 30-kDa C/EBP alpha, and (c) an unidentified 20-kDa factor termed p20- CRE/IRS Binding Protein (p20-C/IBP). These proteins have a 30-fold greater affinity for the CRE at room temperature, a difference explained by the rapid dissociation rate of protein bound to the IRS, since the association rate of protein binding to both the IRS and CRE is the same. Protease digestion experiments suggest that the proteins bind to the CRE and IRS in different conformations. The IRS and CRE both function in the context of a heterologous promoter to mediate effects of insulin and cAMP, respectively, but, although the PEPCK IRS and CRE bind common proteins, the PEPCK CRE is not a functional IRS and the PEPCK IRS is not a functional CRE.