Inducible transgene expression in CHO cells using an artificial transcriptional activator with estrogen-binding domain

Biopharmaceuticals, including therapeutic antibodies, are rapidly growing products in the pharmaceutical market. Mammalian cells, such as Chinese hamster ovary (CHO) cells, are widely used as production hosts because recombinant antibodies require complex three-dimensional structures modified with sugar chains. Recombinant protein production using mammalian cells is generally performed with cell growth. In this study, we developed a technology that controls cell growth and recombinant protein production to induce recombinant protein production with predetermined timing. Expression of green fluorescent protein (GFP) gene and a single-chain antibody fused with the Fc-region of the human IgG1 (scFv-Fc) gene can be induced and mediated by the estrogen receptor-based artificial transcription factor Gal4-ERT2-VP16 and corresponding inducer drugs. We generated CHO cells using an artificial gene expression system. The addition of various concentrations of inducer drugs to the culture medium allowed control of proliferation and transgene expression of the engineered CHO cells. Use of 4-hydroxytamoxifen, an antagonist of estrogen, as an inducing agent yielded high gene expression at a concentration more than 10-fold lower than that of β-estradiol. When scFv-Fc was produced under inducing conditions, continuous production was possible for more than 2 weeks while maintaining high specific productivity (57 pg cell-1 day-1 ). This artificial gene expression control system that utilizes the estrogen response of estrogen receptors can be an effective method for inducible production of biopharmaceuticals.

High-Level Production of scFv-Fc Antibody Using an Artificial Promoter System with Transcriptional Positive Feedback Loop of Transactivator in CHO Cells

With the increasing demand for therapeutic antibodies, CHO cells have become the de facto standard as producer host cells for biopharmaceutical production. High production yields are required for antibody production, and developing a high-titer production system is increasingly crucial. This study was established to develop a high-production system using a synthetic biology approach by designing a gene expression system based on an artificial transcription factor that can strongly induce the high expression of target genes in CHO cells. To demonstrate the functionality of this artificial gene expression system and its ability to induce the high expression of target genes in CHO cells, a model antibody (scFv-Fc) was produced using this system. Excellent results were obtained with the plate scale, and when attempting continuous production in semi-continuous cultures using bioreactor tubes with high-cell-density suspension culture using a serum-free medium, high-titer antibody production at the gram-per-liter level was achieved. Shifting the culture temperature to a low temperature of 33 °C achieved scFv-Fc concentrations of up to 5.5 g/L with a specific production rate of 262 pg/(cell∙day). This artificial gene expression system should be a powerful tool for CHO cell engineering aimed at constructing high-yield production systems.

Primary ileal volvulus in neonates: radiologic findings in two cases

Two cases of primary small bowel volvulus in neonates are presented. On abdominal plain radiographs pseudotumor sign was seen in both cases. CT showed intensely distended fluid-filled small bowel loops on the right side of the abdomen and diffuse distention of the proximal small bowel loops with air-fluid levels. US also showed distended fluid-filled loops containing echogenic foci without peristalsis. We consider that CT and US can play important roles in the diagnosis of small bowel volvulus in neonates.

[CT findings of non-traumatic colorectal perforation]

We retrospectively analyzed CT scans from 23 patients with non-traumatic colorectal perforation. We compared the sensitivity of CT and plain film radiography in the detection of free gas. Free gas was observed in 7 of the 23 cases (30.4%) on plain film radiography and 16 of the 23 cases (69.6%) on CT. Retroperitoneal abscess was demonstrated in 6 of the 7 patients without free gas on CT. Extraluminal air and abscess covered by the omentum and mesenterium were demonstrated in the remaining one patient. The site of perforation was identified in 19 of the 23 patients (82.6%) on CT. CT was useful for demonstrating retroperitoneal free gas, changes in mesenteric fat, extraluminal feces, and tumors. We conclude that CT is indicated in cases of suspected colorectal perforation.

Longitudinal changes in peritoneal equilibration test with or without peritonitis in children

This study was conducted to evaluate longitudinal changes in the peritoneal equilibration test (PET) in children treated with continuous peritoneal dialysis (CPD). The effects of prolonged CPD and episodes of peritonitis on the PET were examined. PET was repeated up to five times in 12 paediatric patients who were subdivided into groups with and without peritonitis. In the peritonitis group (n = 6), the dialysate/plasma (D/P) creatinine ratio at a 4-h dwell time decreased progressively with time on CPD in five of six patients. In a comparison of the initial and final PETs performed at a mean interval of 22.8 +/- 11.6 months, the D/P creatinine ratio in the final PET was significantly lower than in the initial PET (P < 0.01). In contrast, in the non-peritonitis group (n = 6), the D/P creatinine ratio in the final PET was unchanged for 28.2 +/- 12.3 months from the initial PET. The D/Do glucose ratio at a 4-h dwell time was unchanged over time in each group. Thus, repeated PET measurements revealed that membrane permeability for creatinine was not affected by prolonged CPD itself, but decreased with time after episodes of peritonitis. Although the protocol for PET is not standardised in children, PET was useful for determining the sequential changes in peritoneal function in such patients on CPD.

A case of congenital nephrotic syndrome associated with positive C1q immunofluorescence

We present a 1-month-old girl with a congenital nephrotic syndrome and unusual histological findings. Immunofluorescence microscopy demonstrated granular mesangial deposition of C1q and electron microscopy revealed electron-dense mesangial deposits. Her heavy proteinuria gradually decreased and the steroid therapy did not have a significant effect. Her renal function was normal throughout the entire period of observation. The clinical evidence and histopathological features of this patient were compatible with C1q nephropathy.

Therapeutic ethanol injection of hepatocellular carcinomas undetectable by angiography and Lipiodol computed tomography

Seven smaller than 2 cm in diameter hepatocellular carcinomas (HCC) undetectable by hepatic arteriography and computed tomography (CT) after intraarterial injection of iodized oil (Lipiodol CT) were diagnosed by ultrasonography-guided fine-needle biopsy in 6 patients. All lesions were treated by percutaneous ethanol injection (PEI) in 1-3 weekly intervals. No recurrences have been demonstrated after 7-15 months. The treatment of HCCs undetectable by angiography and Lipiodol CT presents a problem as transcatheter arterial embolization is considered ineffective due to poor vascularity. PEI appears to be an excellent treatment for these small HCCs.

Multiseptate gallbladder: computed tomographic appearance

We report a case of multiseptate gallbladder in a 43-year-old female with ultrasonographic and computed tomographic (CT) findings. The postcontrast CT delineated multiple septations with honeycomb appearance in the gallbladder. This finding should raise the suspicion of multiseptate gallbladder.

Five-year clinical course of aortic regurgitation without coronary aneurysm following Kawasaki disease

Kawasaki disease has recently been considered as a major cause of acquired valvular diseases in infants and children. But there have been few reports on the clinical course of the lesions caused by this disease, particularly aortic regurgitation. In February 1982, we examined a six-month-old male infant who had Sellers third degree aortic regurgitation (AR) and Sellers first degree mitral regurgitation (MR) without discernible dilatation, aneurysm formation or stenosis of the coronary arteries, and in January 1987 we performed a second cardiac catheterization in order to estimate the progress of these lesions. The results were: 1) His AR showed no apparent worsening; 2) His MR had completely recovered; 3) His volume and pressure studies were almost normal. The catheterization data were compatible with those of other clinical examinations. He no longer had cardiac enlargement as seen on a chest roentgenogram, and there were no signs of left ventricular hypertrophy on an electrocardiogram (ECG).

[Effective radiation therapy of two cases of primary Ewing's sarcoma of the rib]

Two cases of primary Ewing's sarcoma of the rib are reported, in which radiation therapy was quite effective. Case 1 was an 18-year-old female who had had an operation and radiation therapy for Ewing's sarcoma of the left 7th rib. She was referred to our hospital after a recurrent tumor was found. Radiation therapy (tumor dose 46.2 Gy) and chemotherapy were given. The tumor disappeared and there has been no relapse for 1 year and 3 months after the treatment. Case 2 was a 2-year-old-infant. Radiation therapy (tumor dose 74 Gy) was given for primary Ewing's sarcoma of the left 6th rib. The tumor became small and was successfully removed at operation. There has been no relapse or distant metastasis for 8 months following the operation. We emphasize the importance of multidisciplinary treatment in case 1 and the usefulness of preoperative radiotherapy in case 2.

Congenital internal mammary artery-to-pulmonary artery fistulas: a case report

A case of congenital internal mammary artery-to-pulmonary artery fistulas is reported. The patient was a 7-year-old boy in whom this condition was suspected from an abnormal shadow in the left upper lung field upon chest X-ray examination and continuous murmur. A definite diagnosis was made by selective angiography of the internal mammary artery. This condition is extremely rare. Our patient is the youngest among the 16 cases which have been reported so far in the English literature. Surgical treatment may be indicated because there is a risk of rupture of the fistula, endarteritis, and congestive heart failure.

Membranous obstruction of the inferior vena cava associated with intrahepatic portosystemic shunt

Two cases of membranous obstruction of the IVC at hepatic portion associated with intrahepatic portosystemic shunts, which presumably represent the persistent vitelline sinusoids, are presented. The association of these two conditions has not been previously reported and may support the congenital etiology of the membranous obstruction of the IVC. The caval membrane was successfully dilated percutaneously with a balloon catheter in each case.

Spontaneous resolution of bilateral renal artery dissection: a case report

We report a case of simultaneous bilateral dissection of the renal arteries with partial renal infarction. Of interest is the fact that the dissection resolved spontaneously during the 1-year followup. The radiology, including angiography, computerized tomography and ultrasonography, findings are described. The etiology and treatment of isolated dissection of the renal artery also are discussed.

Mesenteric varices demonstrated by transhepatic portography

A case of mesenteric varices draining into the left renal vein is reported. The varices were well demonstrated by percutaneous transhepatic portography and were obliterated. This disease entity should be considered in the differential diagnosis of patients with lower gastrointestinal tract hemorrhage and portal hypertension.

Double aortic arch: axial angiography with concomitant esophagogram: report of a case

A case of functioning double aortic arch in a 6-month-old boy is presented. The value of angled-view angiography with concomitant esophagogram is stressed, because it offers exact anatomical diagnosis and helps in determining the location of surgical division.

Computed tomography of multicystic kidney

A case of multicystic kidney diagnosed by computed tomography (CT) and confirmed at surgery is presented. On CT, the lesion appeared as an abnormal mass composed of numerous walled, low density areas of varying sizes consistent with the surgical finding of congenital multicystic kidney.

Right-sided cervical aortic arch associated with tetralogy of Fallot and peculiar tortuosity of the descending aorta

A right-sided cervical aortic arch, tetralogy of Fallot, and a peculiar tortuosity of the descending aorta in which the aorta formed triple loops were diagnosed by angiocardiography in a 12-year-old girl. Histologic examination of the biopsied wall of the left subclavian artery, taken at the time of a Blalock-Taussig anastomosis, revealed no elastic-tissue defect.