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2.
Support Care Cancer ; 26(1): 261-267, 2018 01.
Article in English | MEDLINE | ID: mdl-28785864

ABSTRACT

While advances in biomedicine exist for cancer, its diagnosis and treatment still bring the threat of mortality to the forefront of spouses' lives. Family conflict is largely due to unmet expectations that generate a lot of physical and emotional distress for spouses, as the primary surrogates. Moreover, older individuals in Hong Kong tend to lack control of where they die and who is present at the end of their lives. Deeper understanding of Chinese spouses' perspectives is needed to generate new insights, particularly in how spouses cope with caregiving. The aim of the study was to explore the Chinese spousal experience with their dying loved ones suffering from terminal cancer. A qualitative study using interpretive description was conducted. Spousal caregivers were purposively recruited through a hospice unit of two regional hospitals in Hong Kong, China. Documentary sources were used as secondary data. Fifteen individuals, consisting of seven men and eight women, participated in individual interviews. The overarching theme was a socially constructed "we" experience of confronting mortality, characterized by five subthemes: (a) balancing end-of-life tension between cure and comfort, (b) prioritizing the family goals and concerns, (c) de-medicalizing caregiving, (d) working for mutuality, and (e) creating a legacy of love. The study suggests that clinicians might consider harnessing the capacity of spouses to help work through confronting experiences of mortality and transforming events for goals that go beyond death. This places a major emphasis on salutary strategies surrounding transitions from curative to palliative care.


Subject(s)
Adaptation, Psychological/physiology , Death , Neoplasms/psychology , Palliative Care/psychology , Spouses/psychology , Terminal Care/psychology , Adult , Aged , Asian People , Female , Humans , Male , Middle Aged , Neoplasms/mortality
3.
Hong Kong Med J ; 21(5): 394-400, 2015 Oct.
Article in English | MEDLINE | ID: mdl-26273016

ABSTRACT

OBJECTIVES: To identify the diagnostic, therapeutic, and prognostic values of transforaminal epidural steroid injection as interventional rehabilitation for lumbar radiculopathy. SETTING: Regional hospital, Hong Kong. PATIENTS: A total of 232 Chinese patients with lumbar radiculopathy attributed to disc herniation or spinal stenosis received transforaminal epidural steroid injection between 1 January 2007 and 31 December 2011. INTERVENTIONS: Transforaminal epidural steroid injection. MAIN OUTCOME MEASURES: Patients' immediate response, response duration, proportion of patients requiring surgery, and risk factors affecting the responses to transforaminal epidural steroid injection for lumbar radiculopathy. RESULTS: Of the 232 patients, 218 (94.0%) had a single level of radiculopathy and 14 (6.0%) had multiple levels. L5 was the most commonly affected level. The immediate response rate to transforaminal epidural steroid injection was 80.2% in 186 patients with clinically diagnosed lumbar radiculopathy and magnetic resonance imaging of the lumbar spine suggesting nerve root compression. Of patients with single-level radiculopathy and multiple-level radiculopathy, 175 (80.3%) and 11 (78.6%) expressed an immediate response to transforaminal epidural steroid injection, respectively. The analgesic effect lasted for 1 to <3 weeks in 35 (15.1%) patients, for 3 to 12 weeks in 37 (15.9%) patients, and for more than 12 weeks in 92 (39.7%) patients. Of the 232 patients, 106 (45.7%) were offered surgery, with 65 (61.3%) undergoing operation, and with 42 (64.6%) requiring spinal fusion in addition to decompression surgery. Symptom chronicity was associated with poor immediate response to transforaminal epidural steroid injection, but not with duration of pain reduction. Poor response to transforaminal epidural steroid injection was not associated with a preceding industrial injury. CONCLUSIONS: The immediate response to transforaminal epidural steroid injection was approximately 80%. Transforaminal epidural steroid injection is a useful diagnostic, prognostic, and short-term therapeutic tool for lumbar radiculopathy. Although transforaminal epidural steroid injection cannot alter the need for surgery in the long term, it is a reasonably safe procedure to provide short-term pain relief and as a preoperative assessment tool.


Subject(s)
Intervertebral Disc Displacement/complications , Lumbar Vertebrae , Radiculopathy/drug therapy , Steroids/administration & dosage , Adult , Aged , Chronic Disease , Decompression, Surgical , Female , Humans , Injections, Epidural , Magnetic Resonance Imaging , Male , Middle Aged , Radiculopathy/etiology , Radiculopathy/surgery , Spinal Fusion , Spinal Stenosis/complications , Time Factors , Treatment Outcome
5.
Int J Tuberc Lung Dis ; 9(6): 627-32, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15971389

ABSTRACT

SETTING: Long-stay prisoners are not regularly screened for TB in Hong Kong. OBJECTIVE: To evaluate tuberculosis (TB) screening in prison. METHOD: All prisoners in a maximum security prison as of 31 October 2001 were screened by chest radiograph (CXR), except for those being followed up for TB or examined by CXR in the last 6 months. RESULTS: A total of 814 male prisoners aged 34.6 +/- 9.6 (mean +/- SD) years were successfully screened. Of 53 cases (6.51%) with radiographic abnormalities, 10 active TB cases (8 culture-negative, 2 culture-positive) were diagnosed, giving an overall yield of 1.23% (95%CI 0.59-2.26). There was no statistical difference in age, ethnicity, place of birth or residency status between those with and those without TB (all P > 0.05). Incarceration > or = 2 years, being in current prison > or = 2 years and not having CXR in last 2 years were associated with TB in univariate analysis (all P < 0.05), but only the last remained an independent predictor in multiple logistic regression (OR 16.8, 95%CI 2.1-132.9, P = 0.008). In that group, the yield was 3.1% (95%CI 1.42-5.89). No further cases were detected in the subsequent 2 years. CONCLUSION: CXR screening of long-stay prisoners gave a high yield in this study.


Subject(s)
Mass Screening , Prisoners , Prisons , Tuberculosis, Pulmonary/prevention & control , Adult , Cohort Studies , Cost-Benefit Analysis , Hong Kong/epidemiology , Humans , Male , Mass Screening/economics , Pilot Projects , Prevalence , Radiography , Risk Factors , Tuberculosis, Pulmonary/diagnostic imaging , Tuberculosis, Pulmonary/epidemiology
6.
Mol Biol Cell ; 12(8): 2257-74, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11514615

ABSTRACT

Polarized epithelial cells maintain the asymmetric composition of their apical and basolateral membrane domains by at least two different processes. These include the regulated trafficking of macromolecules from the biosynthetic and endocytic pathway to the appropriate membrane domain and the ability of the tight junction to prevent free mixing of membrane domain-specific proteins and lipids. Cdc42, a Rho family GTPase, is known to govern cellular polarity and membrane traffic in several cell types. We examined whether this protein regulated tight junction function in Madin-Darby canine kidney cells and pathways that direct proteins to the apical and basolateral surface of these cells. We used Madin-Darby canine kidney cells that expressed dominant-active or dominant-negative mutants of Cdc42 under the control of a tetracycline-repressible system. Here we report that expression of dominant-active Cdc42V12 or dominant-negative Cdc42N17 altered tight junction function. Expression of Cdc42V12 slowed endocytic and biosynthetic traffic, and expression of Cdc42N17 slowed apical endocytosis and basolateral to apical transcytosis but stimulated biosynthetic traffic. These results indicate that Cdc42 may modulate multiple cellular pathways required for the maintenance of epithelial cell polarity.


Subject(s)
Cell Membrane/metabolism , Cell Polarity , Protein Transport/physiology , Tight Junctions/metabolism , cdc42 GTP-Binding Protein/metabolism , Actins/metabolism , Animals , Cell Line , Cytoskeleton/metabolism , Dogs , Electric Impedance , Endocytosis/physiology , Epidermal Growth Factor/metabolism , Golgi Matrix Proteins , Immunoblotting , Immunoglobulin A/metabolism , Inulin/metabolism , Membrane Proteins/metabolism , Microscopy, Fluorescence , Occludin , Phosphoproteins/metabolism , Recombinant Fusion Proteins/metabolism , Tight Junctions/ultrastructure , Zonula Occludens-1 Protein , cdc42 GTP-Binding Protein/genetics
7.
Mol Biol Cell ; 11(6): 2131-50, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10848634

ABSTRACT

When fluid-phase markers are internalized from opposite poles of polarized Madin-Darby canine kidney cells, they accumulate in distinct apical and basolateral early endosomes before meeting in late endosomes. Recent evidence suggests that significant mixing of apically and basolaterally internalized membrane proteins occurs in specialized apical endosomal compartments, including the common recycling endosome and the apical recycling endosome (ARE). The relationship between these latter compartments and the fluid-labeled apical early endosome is unknown at present. We report that when the apical recycling marker, membrane-bound immunoglobulin A (a ligand for the polymeric immunoglobulin receptor), and fluid-phase dextran are cointernalized from the apical poles of Madin-Darby canine kidney cells, they enter a shared apical early endosome (

Subject(s)
Endosomes/metabolism , Animals , Biomarkers , Cell Compartmentation , Cell Line , Cell Polarity/physiology , Centrioles/metabolism , Cytoskeleton/metabolism , Dextrans/metabolism , Dogs , Immunoglobulin A/metabolism , Intracellular Fluid/metabolism , Intracellular Membranes/metabolism , Membrane Proteins/metabolism , Microtubules/metabolism , Rabbits , Temperature , Vesicular Transport Proteins , rab GTP-Binding Proteins/metabolism
8.
J Biol Chem ; 275(32): 24341-7, 2000 Aug 11.
Article in English | MEDLINE | ID: mdl-10825156

ABSTRACT

Polyphosphoinositides regulate numerous steps in membrane transport. The levels of individual phosphatidylinositols are controlled by specific lipid kinases, whose activities and localization are in turn regulated by a variety of effectors. Here we have examined the effect of overexpression of frequenin, a modulator of phosphatidylinositol 4-kinase activity, on biosynthetic and postendocytic traffic in polarized Madin-Darby canine kidney cells. Endogenous frequenin was identified in these cells by polymerase chain reaction, Western blotting, and indirect immunofluorescence. Adenoviral-mediated overexpression of frequenin had no effect on early Golgi transport of membrane proteins, as assessed by acquisition of resistance to endoglycosidase H. However, delivery of newly synthesized influenza hemagglutinin from the trans-Golgi network to the apical cell surface was severely inhibited in cells overexpressing frequenin, whereas basolateral delivery of the polymeric immunoglobulin receptor was unaffected. Overexpression of frequenin did not affect postendocytic trafficking steps including apical and basolateral recycling and basal-to-apical transcytosis. We conclude that frequenin, and by inference, phosphatidylinositol 4-kinase, plays an important and selective role in apical delivery in polarized cells.


Subject(s)
1-Phosphatidylinositol 4-Kinase/metabolism , Calcium-Binding Proteins/metabolism , Hemagglutinin Glycoproteins, Influenza Virus/biosynthesis , Nerve Tissue Proteins/metabolism , Adenoviridae , Animals , Brain/metabolism , Calcium-Binding Proteins/genetics , Cell Line , Cell Polarity , Dogs , Fluorescent Antibody Technique, Indirect , Genetic Vectors , Golgi Apparatus/metabolism , Hemagglutinin Glycoproteins, Influenza Virus/genetics , Kidney , Kinetics , Nerve Tissue Proteins/genetics , Neuronal Calcium-Sensor Proteins , Neuropeptides , Rats , Recombinant Proteins/biosynthesis , Recombinant Proteins/metabolism , Transfection
9.
Mol Biol Cell ; 11(1): 287-304, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10637309

ABSTRACT

Madin-Darby canine kidney (MDCK) cells expressing constitutively active Rac1 (Rac1V12) accumulate a large central aggregate of membranes beneath the apical membrane that contains filamentous actin, Rac1V12, rab11, and the resident apical membrane protein GP-135. To examine the roles of Rac1 in membrane traffic and the formation of this aggregate, we analyzed endocytic and biosynthetic trafficking pathways in MDCK cells expressing Rac1V12 and dominant inactive Rac1 (Rac1N17). Rac1V12 expression decreased the rates of apical and basolateral endocytosis, whereas Rac1N17 expression increased those rates from both membrane domains. Basolateral-to-apical transcytosis of immunoglobulin A (IgA) (a ligand for the polymeric immunoglobulin receptor [pIgR]), apical recycling of pIgR-IgA, and accumulation of newly synthesized GP-135 at the apical plasma membrane were all decreased in cells expressing Rac1V12. These effects of Rac1V12 on trafficking pathways to the apical membrane were the result of the delivery and trapping of these proteins in the central aggregate. In contrast to abnormalities in apical trafficking events, basolateral recycling of transferrin, degradation of EGF internalized from the basolateral membrane, and delivery of newly synthesized pIgR from the Golgi to the basolateral membrane were all relatively unaffected by Rac1V12 expression. Rac1N17 expression had little or no effect on these postendocytic or biosynthetic trafficking pathways. These results show that in polarized MDCK cells activated Rac1 may regulate the rate of endocytosis from both membrane domains and that expression of dominant active Rac1V12 specifically alters postendocytic and biosynthetic membrane traffic directed to the apical, but not the basolateral, membrane.


Subject(s)
Endocytosis/physiology , Membrane Glycoproteins/metabolism , Nerve Tissue Proteins/metabolism , rac1 GTP-Binding Protein/biosynthesis , Actins/metabolism , Animals , Biological Transport , Biomarkers , Cell Line , Cell Polarity , Contactin 1 , Cytoskeleton/metabolism , Dogs , Endosomes , Epithelial Cells/cytology , Epithelial Cells/drug effects , Epithelial Cells/metabolism , Gene Expression , Membrane Glycoproteins/biosynthesis , Mutagenesis , Nerve Tissue Proteins/biosynthesis , Nocodazole/pharmacology , rac1 GTP-Binding Protein/genetics
10.
Mol Biol Cell ; 10(12): 4369-84, 1999 Dec.
Article in English | MEDLINE | ID: mdl-10588664

ABSTRACT

Efficient postendocytic membrane traffic in polarized epithelial cells is thought to be regulated in part by the actin cytoskeleton. RhoA modulates assemblies of actin in the cell, and it has been shown to regulate pinocytosis and phagocytosis; however, its effects on postendocytic traffic are largely unexplored. To this end, we expressed wild-type RhoA (RhoAWT), dominant active RhoA (RhoAV14), and dominant inactive RhoA (RhoAN19) in Madin-Darby canine kidney (MDCK) cells expressing the polymeric immunoglobulin receptor. RhoAV14 expression stimulated the rate of apical and basolateral endocytosis, whereas RhoAN19 expression decreased the rate from both membrane domains. Polarized basolateral recycling of transferrin was disrupted in RhoAV14-expressing cells as a result of increased ligand release at the apical pole of the cell. Degradation of basolaterally internalized epidermal growth factor was slowed in RhoAV14-expressing cells. Although apical recycling of immunoglobulin A (IgA) was largely unaffected in cells expressing RhoAV14, transcytosis of basolaterally internalized IgA was severely impaired. Morphological and biochemical analyses demonstrated that a large proportion of IgA internalized from the basolateral pole of RhoAV14-expressing cells remained within basolateral early endosomes and was slow to exit these compartments. RhoAN19 and RhoAWT expression had little effect on these postendocytic pathways. These results indicate that in polarized MDCK cells activated RhoA may modulate endocytosis from both membrane domains and postendocytic traffic at the basolateral pole of the cell.


Subject(s)
Endocytosis/physiology , rhoA GTP-Binding Protein/metabolism , 3,3'-Diaminobenzidine/pharmacology , Actins/metabolism , Animals , Cell Line , Cell Polarity/physiology , Cytoskeleton/metabolism , Dogs , Endosomes/metabolism , Epidermal Growth Factor/metabolism , Fluorescent Antibody Technique , Immunoglobulin A/metabolism , Microscopy, Confocal , Mutation , Receptors, Fc/metabolism , rhoA GTP-Binding Protein/genetics
11.
Prostate Cancer Prostatic Dis ; 2(5-6): 264-276, 1999 12.
Article in English | MEDLINE | ID: mdl-12497173

ABSTRACT

Improving early detection, diagnosis, treatment monitoring and prognosis of cancer will require rapid and high throughput detection, identification, and measurement of multiple biomarkers. In this study, we demonstrate the versatility of the innovative SELDI ProteinChip(R) MS technology for the rapid, reproducible and simultaneous identification of four well-characterized prostate cancer-associated (PCA) biomarkers, prostate specific antigen (free and complexed forms), prostate specific peptide, prostate acid phophatase and prostate specific membrane antigen in cell lysates, serum and seminal plasma. Proteins corresponding to the mass of these biomarkers could readily be captured and detected using either chemically defined or antibody coated ProteinChip(R) arrays. Several (yet to be identified) proteins were found upregulated in cell lysates of pure populations of PCA cells procured by laser capture microdissection (LCM) when compared with mass spectra of normal cell lysates. Coupling LCM with SELDI provides tremendous opportunities to discover and identify the signature proteins associated with each stage of tumor development. Collectively, these observations demonstrate the potential of SELDI for the discovery and simultaneous detection of and clinical assay development for PCA biomarkers in complex biological mixtures.

12.
Hear Res ; 123(1-2): 201-5, 1998 Sep.
Article in English | MEDLINE | ID: mdl-9745967

ABSTRACT

This normative study investigates the efficiency of using the maximum length sequence (MLS) technique applied to auditory brainstem evoked response (ABR) testing to estimate hearing thresholds. Using a commercially available system, ABRs were recorded in sixteen subjects at two conventional rates--9.1 and 33.3 clicks/s--and six MLS rates between 88.8 and 1000 clicks/s. Each subject was tested at five stimulus levels from 60 down to 10 dBnHL. The wave JV amplitude input-output (I/O) functions, relative signal to noise ratio (SNR) and speed of test were calculated for all conditions. The JV amplitude and detectability decrease as the stimulus rate increases and level decreases. The latency of JV increases as the stimulus rate increases and the intensity decreases. While the slope of the amplitude I/O function was maximal at 200 clicks/s, at 300 clicks/s it was comparable with that obtained at conventional rates. At higher rates, the slope of the I/O function decreases. When compared with the conventional recording rate of 33.3 clicks/s there is a small improvement in SNR for MLS rates between 200 and 600 clicks/s at levels above 30 dBnHL. The calculated speed improvement at 300 clicks/s is a factor between 1.4 to 1.6 at a screening level of 30-40 dBnHL. It is felt therefore that there may be a small advantage to using MLS in screening and that the optimal rate for this lies at around 200 to 300 clicks/s. However even at these rates, as a consequence of the adaptation of the response with both rate and level, the improvement in SNR or speed of test would be modest when estimating threshold.


Subject(s)
Auditory Threshold/physiology , Evoked Potentials, Auditory, Brain Stem/physiology , Acoustic Stimulation , Adult , Female , Humans
13.
J Biol Chem ; 273(28): 17732-41, 1998 Jul 10.
Article in English | MEDLINE | ID: mdl-9651373

ABSTRACT

Fusion of recycling and transcytotic vesicles with the apical and basolateral plasma membrane domains of Madin-Darby canine kidney (MDCK) cells requires the N-ethylmaleimide-sensitive factor and is sensitive to botulinum neurotoxin serotype E (BoNT/E). BoNT/E is thought to selectively proteolyze the 25,000-dalton synaptosomal associated protein (SNAP-25), a protein found in neurons or cells of neuroendocrine origin. However, SNAP-25 is not found in MDCK cells. One possible target for BoNT/E in MDCK cells is SNAP-23, a newly described SNAP-25 homolog that is found in several organs including kidney. Currently, the function of SNAP-23 is unknown. We have reconstituted transferrin recycling in permeabilized MDCK cells to assess the role of SNAP-23 in the endocytic traffic of this protein. We find that: (i) SNAP-23 is expressed in MDCK cells and is found both at the basolateral plasma membrane and associated with apical and basolateral vesicles, (ii) canine SNAP-23 is cleaved by BoNT/E, (iii) transferrin recycling is N-ethylmaleimide-sensitive factor-dependent and BoNT/E-sensitive, and (iv) addition of either exogenous SNAP-23 or anti-SNAP-23 antibodies inhibits ligand recycling. Our observations suggest that SNAP-23 may be required for fusion of recycling vesicles with the basolateral membrane of polarized MDCK cells.


Subject(s)
Carrier Proteins/metabolism , Transferrin/metabolism , Animals , Base Sequence , Cell Line , Cell Membrane/metabolism , DNA Primers , Dogs , Endocytosis , Humans , Kidney/cytology , Kidney/metabolism , Qb-SNARE Proteins , Qc-SNARE Proteins , Streptolysins
14.
J Biol Chem ; 272(5): 2607-14, 1997 Jan 31.
Article in English | MEDLINE | ID: mdl-9006893

ABSTRACT

Cytoplasmic Hsc70 is a multifunctional molecular chaperone. It is hypothesized that accessory proteins are used to specify the diverse chaperone activities of Hsc70. A 16-kDa cytosolic protein (p16) co-purified with Hsc70 obtained from a fish hepatocyte cell line, PLHC-1. Hsc70 also co-immunoprecipitated with p16 from PLHC-1 cells and fish liver. p16 was identified as a member of the Nm23/nucleoside diphosphate (NDP) kinase family based on its amino acid sequence similarity, NDP kinase activity, and recognition by anti-human NDP kinase-A antibody. This antibody also co-immunoprecipitated Hsc70 and NDP kinase from human HepG2 cells. p16 monomerized Hsc70 and released Hsc70 from pigeon cytochrome c peptide (Pc) but not from FYQLALT, a peptide specifically designed for high affinity binding. Therefore, p16 may modulate Hsc70 function by maintaining Hsc70 in a monomeric state and by dissociating unfolded proteins from Hsc70 either through protein-protein interactions or by supplying ATP indirectly through phosphate transfer. p16 did not affect basal or unfolded protein-stimulated ATPase activity of bovine brain Hsc70 using in vitro assays. Interestingly, bovine liver NDP kinase did not dissociate the Hsc70.Pc complex. In addition, two nonconservative amino acid subsitutions were found near the amino terminus of p16. Therefore, p16 may be a unique Nm23/NDP kinase that functions as an accessory protein for cytosolic Hsc70 in eukaryotes.


Subject(s)
Adenosine Triphosphatases/metabolism , Carrier Proteins/metabolism , HSP70 Heat-Shock Proteins , Liver/metabolism , Monomeric GTP-Binding Proteins , Nucleoside-Diphosphate Kinase/metabolism , Transcription Factors/metabolism , Adenosine Triphosphatases/isolation & purification , Amino Acid Sequence , Animals , Antibodies , Binding Sites , Carcinoma, Hepatocellular , Carrier Proteins/isolation & purification , Cattle , Cell Line , Chromatography, Affinity , Cyprinidae , Cytochrome c Group/chemistry , Cytoplasm/metabolism , Electrophoresis, Polyacrylamide Gel , HSC70 Heat-Shock Proteins , Humans , Liver Neoplasms , Macromolecular Substances , Models, Biological , Molecular Chaperones/metabolism , Molecular Sequence Data , Molecular Weight , NM23 Nucleoside Diphosphate Kinases , Peptide Fragments/chemistry , Sequence Homology, Amino Acid , Transcription Factors/chemistry , Transcription Factors/isolation & purification , Tumor Cells, Cultured
15.
Cell Stress Chaperones ; 1(1): 78-89, 1996 Apr.
Article in English | MEDLINE | ID: mdl-9222592

ABSTRACT

Differential scanning calorimetry was used to monitor the thermal transitions of the 70 kDa heat shock cognate protein (Hsc70). Hsc70 had endothermic transitions with midpoints (Tm) at 59 degrees C and 63 degrees C in the absence and presence of ATP, respectively, and a similar increase in Tm was observed using intrinsic fluorescence of tryptophan. Combined with increased exposure at 60 degrees C of non-polar residues of Hsc70 to which the hydrophobic, fluorescent probe ANS bound, these data indicate that the endotherms represent thermal denaturation and that bound nucleotide stabilizes Hsc70. An exothermic transition (Tm = 66 degrees C) was detected by calorimetry for Hsc70-apocytochrome c (apo c) complexes. An increase in intrinsic fluorescence with the same Tm and increased turbidity indicated aggregation of the denatured Hsc70-apo c. A novel finding was an exothermic transition of Hsc70 beginning at about 30 degrees C (Tm = 41 degrees C). No changes in either intrinsic fluorescence or ANS fluorescence attributable to protein transitions were detected in this temperature range. Examination of samples run on native polyacrylamide gels indicated that this exothermic transition was not due to Hsc70 aggregation or multimer formation. However, Hsc70 was protease-resistant at 20 degrees C, sensitive at 40 degrees C and resistant when returned to 20 degrees C, indicating that this exotherm is associated with a reversible conformational change. As an assay for Hsc70 chaperoning function, complex formation was measured as a function of temperature using a variety of substrates including the model unfolded protein apo c, a pigeon cytochrome c fragment, a representative hydrophobic-aromatic peptide FYQLALT, and a representative hydrophobic-basic motif NIVRKKK. For all of these substrates, the amount of complex formed increased with increasing temperature over the same range as the 41 degrees C exotherm. It is proposed that a conformational change exposes polar and charged residues in Hsc70 which subsequently become hydrated, resulting in an active chaperone. Hsc70 may be a thermal sensor that matches the supply of chaperoning activity with demand for it over the physiological temperature range of mammalian cells. Thermal activation of Hsc70 may also have a role in acquired thermotolerance.


Subject(s)
Body Temperature/physiology , Carrier Proteins/physiology , Escherichia coli Proteins , HSP70 Heat-Shock Proteins/physiology , Heat-Shock Response/physiology , Amino Acid Sequence , Animals , Apolipoproteins C/metabolism , Calorimetry, Differential Scanning , Carrier Proteins/analysis , Cattle , Fluorometry , HSC70 Heat-Shock Proteins , HSP70 Heat-Shock Proteins/analysis , Molecular Chaperones/analysis , Molecular Structure , Protein Conformation , Silver Staining , Tryptophan
16.
J Biol Chem ; 270(34): 19839-44, 1995 Aug 25.
Article in English | MEDLINE | ID: mdl-7649995

ABSTRACT

A 15-mer phage display random peptide library was screened with purified bovine Hsc70, and nucleotide sequence analysis of the selected clones showed a large enrichment for peptides containing basic sequences with at least KK, KR, or RR. Binding affinity for Hsc70 of representative peptides increased dramatically for heptamers compared with hexamers. The peptide NIVRKKK had the highest affinity for Hsc70, and substitution analyses showed that hydrophobic residues followed by basic residues play important roles in maintaining this affinity. In contrast, NIVRKKK was a weaker stimulator of the Hsc70 ATPase activity compared with pigeon cytochrome c peptide and FYQLALT, a peptide optimized for binding to Hsc70. FYQLALT effectively blocked the binding of NIVRKKK to Hsc70, possibly by causing a conformational change that masked Hsc70's binding site for the basic peptide. Two hypotheses are offered to explain the two different peptide motifs. First, it is proposed that Hsc70 recognizes two different amino acid sequence motifs in its dual roles of chaperoning proteins to organelles (NIVRKKK-like sequences) and facilitating protein folding (FYQLALT-like sequences). Second, the NIVRKKK motif may be used to bind certain folded proteins with which Hsc70 interacts, such as itself, p53, and Dnaj2.


Subject(s)
Carrier Proteins/genetics , Carrier Proteins/metabolism , HSP70 Heat-Shock Proteins , Oligopeptides/genetics , Oligopeptides/metabolism , Peptides/genetics , Peptides/metabolism , Amino Acid Sequence , Animals , Binding Sites , Binding, Competitive , Cattle , Cytochrome c Group/genetics , Gene Library , HSC70 Heat-Shock Proteins , In Vitro Techniques , Inovirus/genetics , Molecular Sequence Data , Organelles/metabolism , Protein Binding , Protein Conformation , Protein Folding
18.
Child Health Care ; 13(2): 89-91, 1984.
Article in English | MEDLINE | ID: mdl-10268933

ABSTRACT

The function of "Senior Therapist" was developed by the social worker and the head nurse at the Inpatient Child Psychiatry Unit of the British Columbia Children's Hospital. The role of the Senior Therapist lead to a modification of the usual medical model by involving other professionals in primary patient care, discharge planning, and follow-up services for the young patients and their families. The program serves as a model of innovative clinical services.


Subject(s)
Child, Hospitalized/psychology , Patient Care Team , Psychiatric Department, Hospital , British Columbia , Child , Child, Preschool , Humans
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