PubMed Health⌕ Search

Biomedical subjects

B Press

Publications and source records attributed to B Press.

11 recordsLinked to original sources
PubMed1998

Mutant Rab7 causes the accumulation of cathepsin D and cation-independent mannose 6-phosphate receptor in an early endocytic compartment.

Stable BHK cell lines inducibly expressing wild-type or dominant negative mutant forms of the rab7 GTPase were isolated and used to analyze the role of a rab7-regulated pathway in lysosome biogenesis. Expression of mutant rab7N125I protein induced a dramatic redistribution of cation-independent mannose 6-phosphate receptor (CI-MPR) from its normal perinuclear localization to large peripheral endosomes. Under these circumstances approximately 50% of the total receptor and several lysosomal hydrolases cofractionated with light membranes containing early endosome and Golgi markers. Late endosomes and lysosomes were contained exclusively in well-separated, denser gradient fractions. Newly synthesized CI-MPR and cathepsin D were shown to traverse through an early endocytic compartment, and functional rab7 was crucial for delivery to later compartments. This observation was evidenced by the fact that 2 h after synthesis, both markers were more prevalent in fractions containing light membranes. In addition, both were sensitive to HRP-DAB- mediated cross-linking of early endosomal proteins, and the late endosomal processing of cathepsin D was impaired. Using similar criteria, the lysosomal membrane glycoprotein 120 was not found accumulated in an early endocytic compartment. The data are indicative of a post-Golgi divergence in the routes followed by different lysosome-directed molecules.

Animals↗
PubMed1996

B cell antigen receptor signaling links biochemical changes in the class II peptide-loading compartment to enhanced processing.

In B cells, processing of antigens in the context of MHC class II molecules is initiated by the binding of antigen to the B cell antigen receptor (BCR). BCR-mediated processing is highly efficient, as a consequence of the BCR's linked roles of delivering antigen to the class II peptide-loading compartment and of signaling for increased antigen-processing activity. Evidence is emerging that receptor signaling regulates intracellular transport through the activities of kinases. These in turn have been implicated in the regulation of small mol. wt GTPases which govern membrane transport. Therefore, we investigated the changes in the phosphoprotein and GTPase profiles associated with the class II peptide-loading compartment following BCR cross-linking. We first show that protein kinase inhibitors, known to block BCR signal transduction, inhibit BCR-enhanced antigen processing, demonstrating the critical dependence of enhanced processing on the signaling activity of the BCR. Consistent with this observation, the phosphoprotein profile of the class II peptide-loading compartment underwent rapid and transient changes following BCR cross-linking. We also observed a marked increase in the low mol. wt GTPases associated with the class II peptide-loading compartment within 5 min of BCR cross-linking. The observed changes in both the phosphoprotein and GTPase profiles associated with the peptide-loading compartment were blocked by kinase inhibitors and were not accompanied by overall gross changes in the protein composition of the subcellular compartments. Thus, signal cascades initiated by BCR cross-linking at the plasma membrane are translated into changes in specific subsets of regulatory proteins associated with the peptide-loading compartment.

Animals↗
PubMed1995

Rab 7: an important regulator of late endocytic membrane traffic.

Rab5 and rab7 proteins belong to a superfamily of small molecular weight GTPases known to be associated with early and late endosomes, respectively. The rab5 protein plays an important regulatory role in early endocytosis, yet the function of rab7 protein was previously uncharacterized. This question was addressed by comparing the kinetics of vesicular stomatitis virus (VSV) G protein internalization in baby hamster kidney cells overexpressing wild-type or dominant negative mutant forms of the rab7 protein (rab7N125I and rab7T22N). Overexpression of wild-type rab7 protein allowed normal transport to late endosomes (mannose 6-phosphate receptor positive), while the rab7N125I mutant caused the VSV G protein to accumulate specifically in early (transferrin receptor positive) endosomes. Horseradish peroxidase and paramyxovirus SV5 hemagglutinin-neuraminidase (HN) were used in quantitative biochemical assays to further demonstrate that rab7 function was not required for early internalization events, but was crucial in downstream degradative events. The characteristic cleavage of SV5 HN in the late endosome distinguishes internalization from transport to later stages of the endocytic pathway. Mutant rab7N125I or rab7T22N proteins had no effect on the internalization of either horseradish peroxidase or SV5 HN protein. In contrast, the mutant proteins markedly inhibited the subsequent cleavage of the SV5 HN protein. Taken together, these data support a key role for rab7, downstream of rab5, in regulating membrane transport leading from early to late endosomes. We compare our findings to those obtained for the yeast homologues Ypt51p, Ypt52p, Ypt53p, and Ypt7p.

Animals↗
PubMed1990

Outpatient or short-stay skin grafting with early ambulation for lower-extremity burns.

Lower-extremity burns and skin grafts to these wounds have traditionally required extended hospitalization. We have used early tangential excision of the burn wounds and application of an Unna boot to fresh skin grafts in an attempt to shorten the hospitalization for such patients. Over a six-month period, 9 patients were treated with Unna boots to fresh skin grafts on the lower extremity. The average hospital stay was 0.9 days (range, 0 to 3 days). Graft take was 85% to 100%; no regrafting was required. Ambulation was begun 24 hours postoperatively. The technique described is a safe, effective, and inexpensive alternative to prolonged immobilization and hospitalization in patients with lower-extremity skin grafts.

Ambulatory Care↗
PubMed1976

[Clinical aspects and pathogenesis of paramyloidosis in plasmacytoma].

In the first phase of inhalation due to the sedimentation of droplets against the walls of the atomizer arises a high loss of fluid in the apparatus. When the air flow was regular a high scattering volume of the consumed fluid quantity from the remedy store container was obtained. In the short-time inhalation this method cannot be used for the estimation of the quantity of medicaments applied to the patient. An exact dosage is possible only by measuring the fog flow and when the exact density of fog is known. When the presuppositions mentioned are not given, the informations about the virtual density of fog which was calculated by means of the analysis of regression, may be obtained.

Adult↗