Insulin-like growth factor-binding protein (IGFBP)-3 and IGFBP-5 share a common nuclear transport pathway in T47D human breast carcinoma cells

Insulin-like growth factor-binding proteins (IGFBPs) play an integral role in modifying insulin-like growth factor actions in a wide variety of cell types. Recent evidence suggests that IGFBP-3 and IGFBP-5 also have effects on cell growth that are insulin-like growth factor-independent. In investigating possible mechanisms for this effect, the intracellular trafficking of IGFBP-3 and IGFBP-5, both of which contain sequences with the potential for nuclear localization, was studied in T47D cells. Nuclear uptake of fluorescently labeled IGFBP-3 and IGFBP-5 was observed in a proportion of T47D cells that appeared to be rapidly dividing. IGFBP-1 and IGFBP-2, which do not possess the putative domain for nuclear translocation, were not transported to the nuclei of T47D cells. When T47D cells were preincubated with excess unlabeled IGFBP-3, nuclear localization of labeled IGFBP-3 or IGFBP-5 was not detected, indicating that their nuclear translocation involves a common pathway. Inhibition of receptor-mediated endocytosis did not affect nuclear uptake of IGFBP-3, suggesting that it uses an alternative non-classical import pathway for transport across the plasma membrane. In addition, a variant form of IGFBP-3 with a mutation in the putative nuclear localization sequence was unable to translocate to the nuclei of T47D cells, suggesting that nuclear translocation of IGFBP-3 was dependent on these carboxyl-terminal basic residues.     

Clinical evaluation of aminocaproic acid for managing traumatic hyphema in children

PURPOSE: The purpose of this study is to determine the incidence of secondary hemorrhage after traumatic hyphema in children and to evaluate the efficacy of epsilon aminocaproic acid in reducing this incidence. METHODS: In a prospective, randomized, double-blind study performed between November 1987 and February 1994, 94 children admitted for traumatic hyphema were assigned to receive either aminocaproic acid (n = 48) (100 mg/kg every 4 hours; maximum, 30 g daily) or placebo (n = 46) for 5 days. Patients who had ingested aspirin in the week preceding admission were excluded from the study. RESULTS: Mean age of the patients was 9.4 years. Black patients comprised 4% of the study population. Secondary hemorrhage occurred in only three patients (3.2%), two from the placebo group and one from the aminocaproic acid group, none of whom had any complications. The duration of hospital stay and the clot resorption times were increased significantly in the aminocaproic acid group (P < 0.001). CONCLUSIONS: The authors report a very low incidence of secondary hemorrhage compared with most previous studies. This difference is likely related to the small proportion of black patients in our study and to the exclusion of patients having ingested aspirin, two factors that seem to be associated with higher rates of rebleeding. The efficacy of aminocaproic acid could not be determined due to the low incidence of hemorrhage. The results of this study, however, suggest that the incidence of secondary hemorrhage in white patients without prior ingestion of aspirin is insufficient to justify routine use of aminocaproic acid in managing traumatic hyphema. Rather, an individualized decision based on the risk factors of each patient would seem more appropriate to avoid a slower clot resorption time and possible side effects of this medication.     

High bit density (100 Mb/cm2) with single-layer Co-Crmedia and ring heads in perpendicular magnetic recording

The signal and noise of single-layer Co₇₉Cr₂₁ media are measured with ring heads to estimate the area density that can be achieved. Densities as high as 100 Mb/cm² (1 μm²/bit) are expected when a signal-to-noise ratio sufficient for an error probability less than 10 ^-5 is required. As a comparison, densities estimated from data from metal-evaporated tape and CrO₂ tape are given. In the frequency response of the single-layer media, an additional minimum was observed for a wavelength slightly larger than the gap length. This is probably caused by the bipolar nature of the perpendicular recording field of a ring head     

Phosphorylation changes the spatial relationship between Glu124-Arg143 and Cys18 and Cys165 of the regulatory light chain in smooth muscle myosin

Regulatory light chain (RLC) mutants, RLC-C18 and RLC-C165, containing a single cysteine at positions 18 and 165 near the N and C terminus, respectively, were each labeled with benzophenone 4-iodoacetamide and exchanged into myosin in their phosphorylated or unphosphorylated forms and then photolyzed. SDS-PAGE showed that, for RLC-C18, the intrachain photo-cross-linking in myosin was inhibited by phosphorylation. For myosin containing RLC-C165, the yield of one intrachain cross-linked band decreased significantly whereas the other was unaffected by phosphorylation. Peptide mapping in conjunction with mass spectrometry showed that Cys165 was cross-linked to site(s) within Ala17-Lys34 independent of the phosphorylation of Ser19. This clearly demonstrates that the proximity between the N- and C-terminal regions of RLC is not affected by phosphorylation. In addition, Cys165 could also be cross-linked to the region of Phe133-Arg143; however, this type of cross-linking was inhibited in the phosphorylated state. For RLC-C18, the cross-linking took place with the region of Glu124-Arg132 or Phe133-Arg143, also only in the unphosphorylated state. Thus, phosphorylation changes the spatial relationship between the region of Glu124-Arg143 and Cys18 and Cys165. In scallop myosin, the region corresponding to Glu124-Arg143 is located at the interfaces between RLC and the essential light chain as well as the heavy chain [Xie, X. , et al. (1994) Nature 368, 306-312]. In light of that work, our results suggest that the region of Glu124-Arg143 is involved in the phosphorylation-dependent signaling and the change in its spatial relationship with respect to the N and C termini of RLC may underlie the activation of the smooth muscle myosin.     

A role for cAMP in long-term depression at hippocampal mossy fiber synapses

Mossy fiber synapses on hippocampal CA3 pyramidal cells, in addition to expressing an NMDA receptor-independent form of long-term potentiation (LTP), have recently been shown to express a novel presynaptic form of long-term depression (LTD). We have studied the mechanisms underlying mossy fiber LTD and present evidence that it is triggered, at least in part, by a metabotropic glutamate receptor-mediated decrease in adenylyl cyclase activity, which leads to a decrease in the activity of the cAMP-dependent protein kinase (PKA) and a reversal of the presynaptic processes responsible for mossy fiber LTP. The bidirectional control of synaptic strength at mossy fiber synapses by activity therefore appears to be due to modulation of the cAMP-PKA signaling pathway in mossy fiber boutons.     

Sexual behaviour and multiple infections in drug abusers

We have studied the prevalence and the serological profile of HBV, HCV, HDV and HIV infections in 137 Italian subjects addicted to the intravenous use of heroine and correlated the virological findings with sexual behaviour. HBV and HCV viremia were also measured in 114 patients. Anti-HCV was detected in 81% of the addicts, and one or more markers of HBV infection were detected in 62.8% (4.4% were carriers of HBsAg, 58.4% had evidence of past HBV infection and 13.1% of the latter also had HDV markers). Anti-HIV was positive in 23.4%; 26% of those positive for anti-HCV and 4.6% of those positive for HBV markers had no other viral marker: none had only anti-HIV. HBV-DNA was negative in the carriers of HBsAg, and HCV-RNA was not detected in any of the HBsAg carriers who also had circulating anti-HCV. Overall, 34% of the anti-HCV positive addicts had HCV-RNA in their blood. The prevalence of the virus infection correlated with the duration of drug addiction but not with sexual behaviour, and sexual behaviour did not influence the acquisition of any virus. HCV infection was most frequent and probably the first infection to occur, but exposure to HBV was also common despite a low rate of HBsAg carriage. The prevalence of HDV infection was high (50%) in the HBsAg carriers, while the overall prevalence of HIV was lower (23%) than expected. Lack of HBV-DNA and HCV-RNA in carriers of HBV with anti-HCV in serum may indicate that HBV and HCV mutually inhibit their own replication.