Premature termination codons destabilize ferredoxin-1 mRNA when ferredoxin-1 is translated.

Ferredoxin-1 (Fed-1) mRNA is poorly translated in dark-treated tobacco (Nicotiana tabacum) leaves, resulting in destabilization of Fed-1 mRNA and a differential light/dark accumulation of the mRNA. Insertion of nonsense codons within the Fed-1 coding sequence disrupts the light regulation of Fed-1 mRNA abundance. Here we show that the nonsense codon effect results primarily from lowering the Fed-1 mRNA stability in light-treated leaf tissue and in rapidly growing tobacco cell cultures, but not in dark-treated leaf tissue. These results suggest that nonsense codons trigger a decay pathway distinct from that seen for Fed-1 mRNA in the dark. We propose that nonsense-mediated decay of nonsense-containing Fed-1 mRNA occurs in light-treated leaves and in non-photosynthetic tobacco culture cells where Fed-1 mRNA is being actively translated.

Lipids closely associated with bone morphogenetic protein (BMP)--and induced heterotopic bone formation. With preliminary observations of deficiencies in lipid and osteoinduction in lathyrism in rats.

An extensive literature on bone morphogenetic protein (BMP) induced generation and regeneration shows general agreement about one observation. The incidence and quantity of bone were greatest when BMP was delivered with a carrier of various biologic and non biologic polymers. In the present research, neutral lipids either endogenous in demineralized bone matrix (DBM) or exogenous in orign were employed as a delivery system for induced heterotopic bone formation in the rectus muscle in rats. Total neutral lipids including cholesterol were measured by correlated gravimetric and Sudan Black B dye binding methods. The heterotopic bone was measured by computer assisted radiomorphometric and histologic methods. Bone formation was measured by total calcium, DNA-P, and alkaline phosphatase activity. Composites of BMP and neutral lipids, separable from phospholipids by extraction with absolute acetone, were consistently osteoinductive. A significant quantity of the total bone lipid was closely associated with and extractable from the bone matrix non-collagenous protein fraction which had high levels of BMP activity. Lathyritic matrix was very low both in dye binding and osteoinductive activity. These observations suggest the possibility that lipids may serve as a BMP carrier in the process of induced bone development.

Evaluation of the accuracy and reproducibility of ambulatory blood pressure monitoring in the very elderly using the Takeda TM-2420.

The accuracy and reproducibility of ambulatory blood pressure monitoring (ABPM) were evaluated in the healthy elderly (> or = 75 years) using the Takeda TM-2420 ambulatory BP monitor (A & D Mercury, Australia). Accuracy was assessed from 90 standardised sphygmomanometer and simultaneously recorded TM-2420 BP measurements in 28 subjects with a BP range of 60-210 mmHg. Reproducibility was determined in 19 subjects who underwent four separate days of ABPM by calculating the standard deviation of the mean differences between pairs of recording days (sdd) and the coefficient of reliability (R). Adaptation was also assessed using R. Of 3471 BP measurements in 19 subjects over 76 recording days, 76% were valid readings. The TM-2420 overestimated simultaneously recorded sphygmomanometer measurements with a bias (mean difference, d +/- sdd) of 13.9 +/- 13.9 mmHg for SBP and 7.5 +/- 6.4 mmHg for DBP. The mean sdd between pairs of recording days was greater for SBP (20.0) than for DBP (9.4) but R was very high for both SBP (0.914) and DBP (0.904). Adaptation effects were not detected. ABPM with the TM-2420 is highly reproducible in the elderly. The TM-2420 performs acceptably in 'field' testing and as it overestimates cuff measurements consistently, appropriate adjustment of recorded TM-2420 BP should be possible in elderly individuals.

Milacemide enhances memory storage and alleviates spontaneous forgetting in mice.

The objective of this study was to evaluate the effectiveness of milacemide as a memory-enhancing drug in mice. Experiment 1 showed that forgetting of active avoidance learning produced by a 14-day training to test delay could be alleviated by milacemide (10 mg/kg) administered before the retention test. Experiment 2 demonstrated that the same dose of milacemide could also attenuate spontaneous forgetting of passive avoidance learning, thereby ruling out nonspecific effects as an explanation for the enhancement of performance following pretesting drug administration. A third experiment showed that the facilitation of retrieval induced by milacemide could be blocked by the NMDA receptor antagonist AP-7, suggesting that the effects of milacemide on memory may be mediated by NMDA receptor activation. A final experiment demonstrated that retention was improved when milacemide was administered immediately following active avoidance training, indicating that the drug can also facilitate remembering by its actions on consolidation and storage processes.