Purified Escherichia coli recA protein catalyzes homologous pairing of superhelical DNA and single-stranded fragments.

Purified Escherichia coli recA protein catalyzed ATP-dependent pairing of superhelical DNA and homologous single-stranded fragments. The product of the reaction: (i) was retained by nitrocellulose filters in 1.5 M NaCl/0.15 M Na citrate at pH 7, (ii) was dissociated at pH 12.3 but was not dissociated by heating at 55 degrees C for 4 min or by treatment with 0.2% sodium dodecyl sulfate and proteinase K, (iii) contained covalently closed circular double-stranded DNA (form I DNA), (iv) contained single-stranded fragments associated with replicative form (RF) DNA, and (v) contained a significant fraction of D-loops as judged by electron microscopy. Linear and nicked circular double-stranded DNA did not substitute well for superhelical DNA; intact circular single-stranded DNA did not substitute well for single-stranded fragments. Homologous combinations of single-stranded fragments and superhelical DNA from phages phiX174 and fd reacted, whereas heterologous combinations did not. The reaction required high concentrations of protein and MgCl2. The ATPase activity of purified recA protein was more than 98% dependent on the addition of single-stranded DNA. In 1 mM MgCl2, the ability of superhelical DNA to support the ATPase activity was two-thirds as good as that of single-stranded DNA.     

Near-fatal cerebral edema associated with adenovirus type 2 infection in a previously healthy infant

We report a near-fatal case of cerebral edema associated with adenovirus type 2 infection in a previously healthy 19-month-old boy. After 3 to 4 d of high fever and a series of seizures, he developed persistent loss of consciousness and irreversible respiratory arrest. Adenovirus type 2 infection was diagnosed by virus isolation from his stool and serology.     

Adrenergic regulation of clock gene expression in mouse liver

A main oscillator in the suprachiasmatic nucleus (SCN) conveys circadian information to the peripheral clock systems for the regulation of fundamental physiological functions. Although polysynaptic autonomic neural pathways between the SCN and the liver were observed in rats, whether activation of the sympathetic nervous system entrains clock gene expression in the liver has yet to be understood. To assess sympathetic innervation from the SCN to liver tissue, we investigated whether injection of adrenaline/noradrenaline (epinephrine/norepinephrine) or sympathetic nerve stimulation could induce mPer gene expression in mouse liver. Acute administration of adrenaline or noradrenaline increased mPer1 but not mPer2 expression in the liver of mice in vivo and in hepatic slices in vitro. Electrical stimulation of the sympathetic nerves or adrenaline injection caused an elevation of bioluminescence in the liver area of transgenic mice carrying mPer1 promoter-luciferase. Under a light-dark cycle, destruction of the SCN flattened the daily rhythms of not only mPer1, mPer2, and mBmal1 genes but also noradrenaline content in the liver. Daily injection of adrenaline, administered at a fixed time for 6 days, recovered oscillations of mPer2 and mBmal1 gene expression in the liver of mice with SCN lesion on day 7. Sympathetic nerve denervation by 6-hydroxydopamine flattened the daily rhythm of mPer1 and mPer2 gene expression. Thus, on the basis of the present results, activation of the sympathetic nerves through noradrenaline and/or adrenaline release was a factor controlling the peripheral clock.     

Ability of myeloma cells to secrete macrophage inflammatory protein (MIP)-1alpha and MIP-1beta correlates with lytic bone lesions in patients with multiple myeloma

Macrophage inflammatory protein (MIP)-1alpha and MIP-1beta have been identified as candidates for multiple myeloma (MM)-derived bone-resorbing factors. To validate the clinical relevance of these observations, we investigated correlations between the ability of MM cells to secrete these chemokines and the extent of MM bone lesions as well as levels of biochemical bone markers in patients with MM. Patients with multiple bone lesions exhibited higher MIP-1alpha and MIP-1beta secretion from MM cells along with elevated urinary deoxypyridinoline (Dpd), without significant elevation of serum bone-specific alkaline phosphatase (BALP) or osteocalcin compared with those with minimal bone lesions. MIP-1alpha and MIP-1beta levels correlated positively with urinary Dpd and serum BALP but not with serum osteocalcin. These results provide further evidence for a causal role of MIP-1alpha and MIP-1beta in the development of lytic bone lesions, and suggest that MM cells suppress osteoblastic bone formation to cause an imbalance of bone turnover and development of destructive bone lesions.     

Malignant serous cystic neoplasm of the pancreas: report of a case and review of the literature

BACKGROUND: In general, serous cystic neoplasms of the pancreas are thought to be benign. Malignant serous cystic neoplasm of the pancreas is a rare clinical entity. CASE REPORT: We report the case of an 87-year-old woman with a serous microcystic neoplasm in the tail of the pancreas that behaved in a malignant fashion. The neoplasm had also invaded the colonic mesentery and splenic hilum. The pancreatic lesion was diagnosed as a large malignant serous cystic neoplasm, and the patient underwent distal pancreatectomy with splenectomy and segmental colectomy. The resected specimen contained a large tumor, 12 x 9 x 8 cm, which occupied the body and tail of the pancreas. Histologically, the tumor was indistinguishable from serous cystadenoma. However, the tumor had invaded surrounding tissues including the splenic vein, and there were splenic invasion and a regional lymph node metastasis. The postoperative course was uneventful. DISCUSSION: There are few reported cases of malignant serous cystic neoplasm, in which malignancy was histologically confirmed in the resected specimen. There are no reports of a negative outcome with complete resection of the tumor. Surgical treatment should be considered for serous cystic neoplasms, especially large ones, because of the malignant potential.