Reactivation of heat-inactivated Ku proteins by heat shock cognate protein HSC73

Purpose: Mouse double-stranded DNA-dependent protein kinase (DNA-PK) activity is heat sensitive. Recovery of heat-inactivated DNA repair activity is a problem after combination therapy with radiation and heat. We investigated the mechanism of recovery of heat-inactivated DNA-PK activity.

Methods: Hybrid cells containing a fragment of human chromosome 8 in scid cells (RD13B2) were used. DNA-PK activity was measured by an in vitro assay. Immunoprecipitation of the nuclear extract was performed with an anti-Ku80 antibody. Proteins co-precipitated with Ku80 were separated by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis and detected by Western blotting using anti-heat shock protein (HSP)72 and anti-heat shock cognate protein (HSC)73 antibodies. HSC73 was overexpressed with the pcDNA3.1 vector. Short hairpin (sh)RNA was used to downregulate HSC73 and HSP72.

Results: The activity of heat-inactivated DNA-PK recovered to about 50% of control during an additional incubation at 37?°C after heat treatment at 44?°C for 15?min in the presence of cycloheximide (which inhibits de novo protein synthesis). Maximal recovery was observed within 3?h of incubation at 37?°C after heat treatment. Constitutively expressed HSC73, which folds newly synthesized proteins, reached maximal levels 3?h after heat treatment using a co-immunoprecipitation assay with the Ku80 protein. Inhibiting HSC73, but not HSP72, expression with shRNA decreased the recovery of DNA-PK activity after heat treatment.

Conclusions: These results suggest that de novo protein synthesis is unnecessary for recovery of some heat-inactivated DNA-PK. Rather, it might be reactivated by the molecular chaperone activity of HSC73, but not HSP72.     

Postoperative development of sarcopenia is a strong predictor of a poor prognosis in patients with adenocarcinoma of the esophagogastric junction and upper gastric cancer

Background

There were few studies assessed the postoperative sarcopenia in patients with cancers. The objective of present study was to assess whether postoperative development of sarcopenia could predict a poor prognosis in patients with adenocarcinoma of esophagogastric junction, (AEG) and upper gastric cancer (UGC).

Systemic arterial supply to the left basal segment without the pulmonary artery: four consecutive cases.

Systemic arterial supply from the descending thoracic aorta to the basal segment of the left lower lobe without a pulmonary artery supply is a rare congenital anomaly within the spectrum of pulmonary sequestration cases. We encountered four consecutive cases, which were treated successfully by three basalectomies and one lower lobectomy to preserve lung function.     

Treatment strategy for synchronous metastases of colorectal cancer: is hepatic resection after an observation interval appropriate?

Background In cases of synchronous colorectal hepatic metastases, the primary colorectal cancer strongly influences on the metastases. Our treatment policy has been to conduct hepatic resection for the metastases at an interval of 3 months after colorectal resection. We examined the appropriateness of interval hepatic resection for synchronous hepatic metastasis. Materials and methods The subjects were 164 patients who underwent resection of hepatic metastasis of colorectal cancer (synchronous, 70 patients; metachronous, 94 patients). Background factors for hepatic metastasis and postoperative results were compared for synchronous and metachronous cases. Results The cumulative survival rate for 164 patients at 3, 5, and 10 years postoperatively was 71.9%, 51.8%, and 36.6%, and the post-resection recurrence rate in remnant livers was 26.8%. Interval resection for synchronous hepatic metastases was conducted in 49 cases after a mean interval of 131 days. No difference was seen in postoperative outcome between synchronous and metachronous cases. Conclusion The outcome was similarly favorable in cases of synchronous hepatic metastasis and in cases of metachronous metastasis. Delaying resection allows accurate understanding of the number and location of hepatic metastases, and is beneficial in determining candidates for surgery and in selecting surgical procedure.     

Binding profile of SM-9018, a novel antipsychotic candidate

The present study employed various receptor-binding assays to clarify the biochemical characteristics of SM-9018. SM-9018 possessed very high affinity for 5-HT2, D2 and 5-HT1A receptors (Ki = 0.61, 1.4 and 2.9 nM, respectively), and it had moderate affinity for alpha 1 and D1 receptors (Ki = 17 and 41 nM, respectively). However, SM-9018 had only negligible affinity for alpha 2, opiate, glutamate, phencyclidine, benzodiazepine and GABAA receptors. These results suggest that SM-9018 may be a novel antipsychotic agent with binding affinity for 5-HT2 and 5-HT1A receptors.     

EFFECTS OF BKCa CHANNELS ON THE REDUCTION OF CYTOSOLIC Ca2+ IN cGMP-INDUCED RELAXATION OF GUINEAPIG TRACHEA

1. In order to examine the mechanisms of cGMP-induced relaxation in airway smooth muscle, the effects of atrial natriuretic peptide (ANP) and 8-brom cGMP on muscle tone were studied by measuring isometric tension, while the effects on cytosolic Ca²⁺ concentrations were studied by measuring the spectra of fura-2 loaded in guinea-pig tracheal strips. 2. Atrial natriuretic peptide and 8-brom cGMP caused a concentration-dependent inhibition of spontaneous tone in the guinea-pig trachea. The relaxant effects of these agents on spontaneous tone were markedly suppressed in the presence of iberiotoxin (IbTX), a selective inhibitor of large-conductance Ca²⁺-activated K⁺ (BKca) channels. Iberiotoxin (30 nmol/L) markedly affected the maximal effect induced by ANP and 8-brom cGMP and augmented EC₇₀ values for ANP and EC₅₀values for 8-brom cGMP approximately 27- and 17-fold, respectively. The inhibitory effects of IbTX on relaxation induced by these agents were diminished in the presence of 1 μmol/L nifedipine, an antagonist of voltage-operated Ca²⁺channels (VOCC). 3. The inhibitory action of ANP and 8-brom cGMP on spontaneous tone was not affected by the presence of 10 μmol/L glibenclamide, an inhibitor of ATP-sensitive K⁺ channels, and 100 nmol/L apamin, an inhibitor of small-conductance Ca²+-activated K⁺ channels. When these agents were applied to tissues precontracted by high (40mmol/L) K⁺, the relaxant effects of these agents markedly diminished. 4. The extracellular Ca²⁺-dependent contraction was inhibited in the presence of 0.3 μmoI/L ANP or 0.1 mmol/L 8-brom cGMP. Concentration—response curves to extracellular Ca²⁺ (0.03—2.4 mmol/L) were markedly diminished by exposure to these agents. The maximal effect induced by extracellular Ca²⁺ was affected by these agents. 5. Atrial natriuretic peptide caused an inhibition of spontaneous tone accompanied by a reduction in the intracellular Ca²⁺ concentration. In the presence of IbTX, the elimination of both muscle tone and cytosolic Ca²⁺ by ANP was suppressed. 6. We conclude that ANP and 8-brom cGMP activate BKca channels and that the inhibition of Ca²⁺ influx through VOCC, mediated by BKca channel activation, may be involved in cGMP-dependent bronchodilation.     

Gliomatosis cerebri with good prognosis

A 52-year-old man was admitted to our clinic with severe headache and bilateral papilledema. Magnetic resonance (MR) images on admission demonstrated diffuse swelling of the cerebral cortex without formation of a tumor mass. Biopsy revealed diffuse infiltration with neoplastic glial cells. After radiation and chemotherapy, the MR images returned to normal. The morphological and neurological features of the present case met the criteria for gliomatosis cerebri. However, this patient showed an unusually good response to radiation and chemotherapy.