State of research, feasibility, safety, acceptability, and outcomes examined on remotely delivered exercises using technology for older adult with cancer: a scoping review.

INTRODUCTION: Technology-based exercise is gaining attention as a promising strategy for increasing physical activity (PA) in older adults with cancer (OACA). However, a comprehensive understanding of the interventions, their feasibility, outcomes, and safety is limited. This scoping review (1) assessed the prevalence and type of technology-based remotely delivered exercise interventions for OACA and (2) explored the feasibility, safety, acceptability, and outcomes in these interventions. METHODS: Studies with participant mean/median age ≥ 65 reporting at least one outcome measure were included. Databases searched included the following: PubMed, CINAHL, Embase, Cochrane Library Online, SPORTDiscus, and PsycINFO. Multiple independent reviewers completed screening and data abstractions of articles in English, French, and Spanish. RESULTS: The search yielded 2339 citations after removing duplicates. Following title and abstract screening, 96 full texts were review, and 15 were included. Study designs were heterogeneous, and sample sizes were diverse (range 14-478). The most common technologies used were website/web portal (n = 6), videos (n = 5), exergaming (n = 2), accelerometer/pedometer with video and/or website (n = 4), and live-videoconferencing (n = 2). Over half (9/15) of the studies examined feasibility using various definitions; feasibility outcomes were reached in all. Common outcomes examined include lower body function and quality of life. Adverse events were uncommon and minor were reported. Qualitative studies identified cost- and time-savings, healthcare professional support, and technology features that encourage engagement as facilitators. CONCLUSION: Remote exercise interventions using technology appear to be feasible and acceptable in OACA. IMPLICATIONS FOR CANCER SURVIVORS: Some remote exercise interventions may be a viable way to increase PA for OACA.

Associations with response to Poly(ADP-ribose) Polymerase (PARP) inhibitors in patients with metastatic breast cancer.

PARP inhibitors (PARPi) have modest antitumor activity in patients with advanced breast cancer and mutation in BRCA. It is unclear whether some subgroups derive greater benefit from treatment. MEDLINE and EMBASE were searched from inception to March 2021 to identify trials of PARPi in patients with metastatic breast cancer. Objective response rate (ORR) and clinical benefit rate (CBR) to PARPi were extracted and pooled in a meta-analysis using the Mantel Haenszel random effects model. Meta-regression explored the influence of patient and tumor characteristics on ORR and CBR. For randomized trials, hazard ratio comparing PARPi to control therapy were pooled using inverse variance and random effects. Analysis included 43 studies comprising 2409 patients. Among these, 1798 (75%) patients had BRCA mutations and 1146 (48%) were triple negative. In 10 studies (28%; n = 680 patients), the PARPi was given in combination with platinum-based chemotherapy. Weighted mean ORR was 45%; 64% when combined with platinum vs 37% with PARPi monotherapy (p < 0.001). Previous platinum-based chemotherapy was associated with lower ORR (p = 0.02). Compared to standard chemotherapy, progression-free survival was improved (HR 0.64, p < 0.001), but there was no difference in overall survival (HR 0.87, p = 0.06). There were no differences in ORR or CBR between BRCA1 and BRCA2 mutations. PARPi are more active in combination with platinum than as monotherapy, with lower response if given as monotherapy after platinum exposure. Significant improvements in ORR translated to modest improvement in progression-free, but not overall survival. There was no association between ORR and BRCA mutations.

Shoulder orthoses for the prevention and reduction of hemiplegic shoulder pain and subluxation: systematic review.

OBJECTIVES: To determine whether shoulder orthoses prevent or reduce gleno-humeral subluxation and hemiplegic shoulder pain. DATA SOURCES: OVID SP, MEDLINE, AMED, CINAHL, PEDro and the Cochrane Central Register of Controlled Trials. REVIEW METHODS: We included: randomised or quasi-randomised controlled trials, controlled before and after studies and observational studies. Two reviewers independently screened, critically appraised papers using the PEDro tool, and extracted data. A descriptive synthesis was performed as there were insufficient data for meta-analysis. RESULTS: Eight studies were included, totalling 186 participants: One randomised controlled trial with 41 participants, one quasi-randomised with 14 participants, one before and after controlled study with 40 participants and five observational studies with 91 participants met the inclusion criteria. Findings suggest that applying an orthosis to an already subluxed shoulder immediately reduced vertical subluxation on X-ray but improvements were not maintained when orthosis was removed. Orthoses with both proximal and distal attachments improved shoulder pain in the majority of stroke patients when worn for four weeks (starting several days or weeks post-stroke). There was no increase in adverse effects of contracture, spasticity or hand oedema when compared to no orthosis. Orthoses were generally well-tolerated and most patients rated the orthosis as comfortable to wear. CONCLUSION: Observational studies suggest that orthoses reduce vertical subluxation whilst in-situ. Available evidence from heterogeneous studies after stroke suggests that orthoses may reduce pain and are well-tolerated with prolonged use. No studies have tested whether subluxation and pain can be prevented by immediate post-stroke application of orthoses.

Hepatic venous outflow obstruction in pediatric liver transplantation: technical considerations in prevention, diagnosis, and management.

HVOO creates significant diagnostic and management dilemmas in pediatric liver transplant recipients, particularly with TVGs (split or reduced-size grafts). Numerous technical variations for the hepatic vein to IVC anastomosis have been described to minimize the incidence of this complication, but no consensus for an optimal anastomotic technique exists. One hundred and thirty-four liver transplants (70 TVGs) were performed in 124 patients between 1994 and 2011. These were divided into two cohorts. Group 1 (95 transplants, 41 TVGs) utilized a continuous running anastomosis. Group 2 (39 transplants, 29 TVGs) implemented a triangulated (three-stitch) anastomosis. All were reviewed for demographics, diagnostics, interventions, and outcome. The overall HVOO incidence was seven of 134 transplants (5.2%) and six of 70 transplants utilizing TVGs (8.6%). Group 1 incidence was five of 41 (12.2%) compared with one of 29 (3.4%; p = 0.20, OR 3.89) in Group 2. Liver Doppler was employed in all patients, and only three suggested HVOO. All patients with HVOO underwent venogram, at a median of 81 days post-transplant. All underwent percutaneous venoplasty and required 1-6 treatments, all resulting in HVOO resolution. Incidence of HVOO has improved since adopting the triangulated anastomosis, although not to a level of statistical significance. US is not adequately sensitive to exclude HVOO. Venogram is recommended in patients with prolonged ascites, and venoplasty has been highly successful in HVOO treatment.

The role of liver transplantation for hepatic adenomatosis in the pediatric population: case report and review of the literature.

Hepatic adenomas are benign lesions often found in young women during childbearing age. These tumors are often solitary but can also be multiple in which case this is referred to as hepatic adenomatosis (HA). HA is defined as having greater than or equal to ten adenomas within an otherwise normal liver. We present a case of a teenager with HA who underwent an orthotopic liver transplant for complications of her HA. To date there are only four reports of teenagers, without an underlying glycogen storage disease, who have undergone a liver transplant for HA. Liver transplantation within the pediatric population is an acceptable treatment for HA that are deemed unresectable.

The effect of recipient-specific surgical issues on outcome of liver transplantation in biliary atresia.

Biliary atresia (BA), the most common reason for orthotopic liver transplantation (OLT) in children, is often accompanied by unique and challenging anatomical variations. This study examines the effect of surgical-specific issues related to the presence of complex vascular anatomic variants on the outcome of OLT for BA. The study group comprised 944 patients who were enrolled in the Studies of Pediatric Liver Transplantation (SPLIT) registry and underwent OLT for BA over an 11-year period. 63 (6.7%) patients met the study definition of complex vascular anomalies (CVA). Patient survival, but not graft survival, was significantly lower in the CVA group, (83 vs. 93 % at 1-year post-OLT). The CVA group had a significantly higher incidence of all reoperations, total biliary tract complications, biliary leaks and bowel perforation. The most frequent cause of death was infection, and death from bacterial infection was more common in the CVA group. Pretransplant portal vein thrombosis and a preduodenal portal vein were significant predictors of patient survival but not graft survival. This study demonstrates that surgical and technical factors have an effect on the outcome of BA patients undergoing OLT. However, OLT in these complex patients is technically achievable with an acceptable patient and graft survival.

Risk factors for rejection and infection in pediatric liver transplantation.

Rejection and infection are important adverse events after pediatric liver transplantation, not previously subject to concurrent risk analysis. Of 2291 children (<18 years), rejection occurred at least once in 46%, serious bacterial/fungal or viral infections in 52%. Infection caused more deaths than rejection (5.5% vs. 0.6% of patients, p < 0.001). Early rejection (<6 month) did not contribute to mortality or graft failure. Recurrent/chronic rejection was a risk in graft failure, but led to retransplant in only 1.6% of first grafts. Multivariate predictors of bacterial/fungal infection included recipient age (highest in infants), race, donor organ variants, bilirubin, anhepatic time, cyclosporin (vs. tacrolimus) and era of transplant (before 2002 vs. after 2002); serious viral infection predictors included donor organ variants, rejection, Epstein-Barr Virus (EBV) naivety and era; for rejection, predictors included age (lowest in infants), primary diagnosis, donor-recipient blood type mismatch, the use of cyclosporin (vs. tacrolimus), no induction and era. In pediatric liver transplantation, infection risk far exceeds that of rejection, which causes limited harm to the patient or graft, particularly in infants. Aggressive infection control, attention to modifiable factors such as pretransplant nutrition and donor organ options and rigorous age-specific review of the risk/benefit of choice and intensity of immunosuppressive regimes is warranted.

Capsule endoscopy for the evaluation of patients with chronic abdominal pain.

BACKGROUND AND STUDY AIMS: Chronic abdominal pain is a common complaint and in many patients even an extensive work-up does not reveal the cause for the pain. Given Imaging wireless capsule endoscopy is a new method for visualization of the entire small bowel. The aim of our study was to determine the role of capsule endoscopy in the evaluation of patients with unexplained chronic abdominal pain. PATIENTS AND METHODS: 20 patients with chronic abdominal pain of 6 - 96 months' duration were enrolled in the study. They had had an extensive diagnostic work-up which was negative. Capsule endoscopy was performed in all patients. RESULTS: Imaging of the small intestine was excellent and the colon was reached in 16 patients. In 14 patients the study was completely normal; in six patients the procedure revealed findings which were considered to be clinically insignificant. All patients tolerated the capsule well and had no adverse effects. CONCLUSION: Capsule endoscopy did not seem to have any significant clinical value in the evaluation of our patients with obscure chronic abdominal pain.

Diuretic induced hyponatraemia in elderly hypertensive women.

Diuretics are recommended as first-line antihypertensive treatment in elderly patients. Although attention is usually paid to prevent hypokalaemia with diuretic therapy, risk of hyponatraemia is often ignored. We performed this study to characterise hypertensive patients at increased risk to develop hyponatraemia. We reviewed charts of hypertensive patients hospitalised in Chaim Sheba Medical Center for hyponatraemia from 1990 to 1997. Patients with other causes of hyponatraemia were excluded. The General Practice Maccabi database was used to estimate age and sex distribution of patients prescribed diuretics for hypertension. We identified 180 hypertensive patients (149 F, 31 M; mean age 76.4 +/- 9.2 years) hospitalised because of hyponatraemia. Across all age groups, odds ratio (OR) to develop hyponatraemia was three times higher for women vs men (OR 3.10, 95% confidence interval (CI): 2.07-4.67). One hundred and sixty-two patients (90%) were older than 65 years. Patients of both sexes older than 65 years were 10 times (and if they were older than 75 years 16 times) more likely to develop hyponatraemia than those younger than 65 years (OR 9.87, 95%, CI: 5.93-16.64). Most patients (74.5%) used a thiazide-based diuretic; only 10% used a low dose (<25 mg/day). In 37% of patients diuretics were used for more than 1 year before hyponatraemia developed. Diuretic-induced hyponatraemia may be insidious and appear even after prolonged diuretics use. Elderly women seem to be at particularly high risk. In this population diuretic use should be associated with close monitoring of sodium and potassium levels.

Long-term efficacy and safety of ritonavir/indinavir at 400/400 mg twice a day in combination with two nucleoside reverse transcriptase inhibitors as first line antiretroviral therapy.

OBJECTIVE: To determine the long-term antiretroviral efficacy and tolerability of dual protease inhibitor (PI) therapy with indinavir (IDV)/ritonavir (RTV) at 400/400 mg twice a day (BID) in combination with two nucleoside reverse trancriptase inhibitors (NRTIs). DESIGN AND METHODS: In an open-label, uncontrolled multicentre clinical trial, antiretroviral therapy naive patients (n = 93) with a high median baseline HIV-1 RNA level of 210 000 copies/mL (range 17 000-2 943 000) and a median CD4 cell count of 195 copies/microL (range 4-656 copies/microL) were started on a regimen of either zidovudine (ZDV)/lamivudine (3TC) (49%), stavudine (d4T)/3TC (38%) or d4T/didanosine (ddI) (14%) plus RTV and IDV, each at 400 mg BID. CD4 cell counts and HIV RNA were determined at 4-week intervals for a duration of 72 weeks. Statistical analysis was performed on treatment as well as by intent to treat, where missing values were counted as failures. RESULTS: HIV RNA levels below the limit of detection were achieved in 59.5% (< 80 copies/mL) and 63% (< 500 copies/mL) of patients according to the intent to treat analysis at week 72. In the on treatment analysis, the proportion of patients reaching an undetectable viral load was 94.5% (< 80 copies/mL) and 100% (< 500 copies/mL), respectively. Apart from diarrhoea and nausea, serum lipid abnormalities were identified as the most prominent adverse reaction. No cases of nephrotoxicity occurred during the entire observation period of 72 weeks. CONCLUSIONS: Our results demonstrate that quadruple therapy with RTV/IDV and two NRTIs induces potent, durable and safe HIV suppression and might be particularly beneficial as a first line therapy for patients with a high baseline viral load.

LTRPC7 is a Mg.ATP-regulated divalent cation channel required for cell viability.

The molecular mechanisms that regulate basal or background entry of divalent cations into mammalian cells are poorly understood. Here we describe the cloning and functional characterization of a Ca2+- and Mg2+-permeable divalent cation channel, LTRPC7 (nomenclature compatible with that proposed in ref. 1), a new member of the LTRPC family of putative ion channels. Targeted deletion of LTRPC7 in DT-40 B cells was lethal, indicating that LTRPC7 has a fundamental and nonredundant role in cellular physiology. Electrophysiological analysis of HEK-293 cells overexpressing recombinant LTRPC7 showed large currents regulated by millimolar levels of intracellular Mg.ATP and Mg.GTP with the permeation properties of a voltage-independent divalent cation influx pathway. Analysis of several cultured cell types demonstrated small magnesium-nucleotide-regulated metal ion currents (MagNuM) with regulation and permeation properties essentially identical to the large currents observed in cells expressing recombinant LTRPC7. Our data indicate that LTRPC7, by virtue of its sensitivity to physiological Mg.ATP levels, may be involved in a fundamental process that adjusts plasma membrane divalent cation fluxes according to the metabolic state of the cell.

Acquisition of a new motor skill is accompanied by changes incutaneomuscular reflex responses recorded from finger muscles in man.

Cutaneomuscular reflex (CMR) responses and motor unit synchronisation have been recorded to investigate possible reorganisation of central nervous pathways in six healthy adults learning a novel skill with the non-dominant hand. Multi-unit surface EMG signals were recorded from first dorsal interosseous (1DI) and abductor digiti minimi (ADM) muscles during sustained flexion of the index finger and abduction of the little finger (flex/ab) and during bilateral controlled finger abduction (ab/ab). CMR responses were elicited by concomitant stimulation of the digital nerves of the index finger at 2.5 times threshold for perception. For training purposes the subject practised the novel flex/ab task phasically at a rate of 1 Hz for 10 min daily for 12 days. Cortically mediated components of the CMR responses recorded from 1DI and ADM were significantly larger in both muscles during training. Taking the data for all subjects together, when subjects performed sustained flex/ab (novel task), the size of the I1 and E2 components were increased by 25 and 55% in IDI and 192 and 167% in ADM (Mann-Whitney U-test, P<0.05). Corresponding values for sustained ab/ab were more modest: 31 and 16% in 1DI and 88 and 54% in ADM. Changes in the size of the spinal E1 component were not the same in each muscle: values for sustained flex/ab and ab/ab were 33 and 31% smaller in 1DI and 89 and 59% larger in ADM. No significant changes were found in the amount of synchrony of motor unit firing between 1DI and ADM when subjects performed either task during training. These results suggest that learning a new motor skill produces changes which take place predominantly in the cortical pathways of the CMR and these may be due to changed connectivity within motor and/or sensory cortex which has previously been shown in the monkey.

Efficacy and safety of twice daily first-line ritonavir/indinavir plus double nucleoside combination therapy in HIV-infected individuals. German Ritonavir/Indinavir Study Group.

OBJECTIVE: To evaluate the virological efficacy and safety of quadruple therapy with two nucleoside analogues and ritonavir (400 mg twice daily) plus indinavir (400 mg twice daily) combination in antiretroviral therapy-naive patients. DESIGN AND METHODS: An open-label, uncontrolled multicentre trial. Antiretroviral therapy-naive patients (n = 90) with high median baseline HIV RNA levels of 220,000 copies/ml (range, 36,000-2,943,000 copies/ml) and median CD4 cell count of 189 x 10(6)/l (range, 4-656 x 10(6)/l) were started on a twice daily regimen of either zidovudine/lamivudine (49%), stavudine/lamivudine (38%) or stavudine/didanosine (13%) plus ritonavir 400 mg twice daily and indinavir 400 mg twice daily combination therapy. CD4 cell counts and HIV RNA were determined at weeks 0, 4, 8, 12, 16, 20, and 24. Statistical analysis was performed on treatment as well as intent-to-treat, where missing values were accounted for as failure. RESULTS: In the intent-to-treat analysis at week 24, the proportion of patients with HIV RNA of < 500 copies/ml, and < 80 copies/ml was 86.7% and 71.1%, respectively. In the on-treatment analysis at week 24, 80.0% of patients had undetectable viral load in the ultrasensitive assay (< 80 copies/ml; n = 80). The quadruple therapy was well tolerated except for mild diarrhoea, initial nausea and increased triglyceride levels. Treatment was stopped in seven (7.7%) patients because of adverse events and three (3.3%) were lost to follow-up. CONCLUSIONS: Our preliminary data suggest that the protease inhibitor combination ritonavir/indinavir plus double nucleoside therapy appears to be effective and safe in short-term treatment (up to 24 weeks).

Astrocytes interact intimately with degenerating motor neurons in mouse amyotrophic lateral sclerosis (ALS).

Astrocytic proliferation and hypertrophy (astrogliosis) are associated with neuronal injury. However, neither the temporal nor the spatial relationship between astrocytes and injured neurons is clear, especially in neurodegenerative diseases. We investigated these questions in a mouse amyotrophic lateral sclerosis (ALS) model. The initial increase in astrogliosis coincided with the onset of clinical disease and massive mitochondrial vacuolation in motor neurons. After disease onset, astrogliosis increased further in parallel with the number of degenerating motor neurons. Examination of individual astrocytes by three-dimensional reconstruction revealed that astrocytes extended their processes toward, wrapped around, and sometimes penetrated vacuoles derived from neuronal mitochondria. These results show a close temporal correlation between the onset of neuronal degeneration and the beginning of astrogliosis in this neurodegenerative disease and reveal a novel spatial relationship that is consistent with the view that astrocytes play an active role in the neuronal degeneration process.

The B-cell transmembrane protein CD72 binds to and is an in vivo substrate of the protein tyrosine phosphatase SHP-1.

BACKGROUND: Signals from the B-cell antigen receptor (BCR) help to determine B-cell fate, directing either proliferation, differentiation, or growth arrest/apoptosis. The protein tyrosine phosphatase SHP-1 is known to regulate the strength of BCR signaling. Although the B-cell co-receptor CD22 binds SHP-1, B cells in CD22-deficient mice are much less severely affected than those in SHP-1-deficient mice, suggesting that SHP-1 may also regulate B-cell signaling by affecting other signaling molecules. Moreover, direct substrates of SHP-1 have not been identified in any B-cell signaling pathway. RESULTS: We identified the B-cell transmembrane protein CD72 as a new SHP-1 binding protein and as an in vivo substrate of SHP-1 in B cells. We also defined the binding sites for SHP-1 and the adaptor protein Grb2 on CD72. Tyrosine phosphorylation of CD72 correlated strongly with BCR-induced growth arrest/apoptosis in B-cell lines and in primary B cells. Preligation of CD72 attenuated BCR-induced growth arrest/death signals in immature and mature B cells or B-cell lines, whereas preligation of CD22 enhanced BCR-induced growth arrest/apoptosis. CONCLUSIONS: We have identified CD72 as the first clear in vivo substrate of SHP-1 in B cells. Our results suggest that tyrosine-phosphorylated CD72 may transmit signals for BCR-induced apoptosis. By dephosphorylation CD72. SHP-1 may have a positive role in B-cell signaling. These results have potentially important implications for the involvement of CD72 and SHP-1 in B-cell development and autoimmunity.

Identification of major binding proteins and substrates for the SH2-containing protein tyrosine phosphatase SHP-1 in macrophages.

The protein tyrosine phosphatase SHP-1 is a critical regulator of macrophage biology, but its detailed mechanism of action remains largely undefined. SHP-1 associates with a 130-kDa tyrosyl-phosphorylated species (P130) in macrophages, suggesting that P130 might be an SHP-1 regulator and/or substrate. Here we show that P130 consists of two transmembrane glycoproteins, which we identify as PIR-B/p91A and the signal-regulatory protein (SIRP) family member BIT. These proteins also form separate complexes with SHP-2. BIT, but not PIR-B, is in a complex with the colony-stimulating factor 1 receptor (CSF-1R), suggesting that BIT may direct SHP-1 to the CSF-1R. BIT and PIR-B bind preferentially to substrate-trapping mutants of SHP-1 and are hyperphosphorylated in macrophages from motheaten viable mice, which express catalytically impaired forms of SHP-1, indicating that these proteins are SHP-1 substrates. However, BIT and PIR-B are hypophosphorylated in motheaten macrophages, which completely lack SHP-1 expression. These data suggest a model in which SHP-1 dephosphorylates specific sites on BIT and PIR-B while protecting other sites from dephosphorylation via its SH2 domains. Finally, BIT and PIR-B associate with two tyrosyl phosphoproteins and a tyrosine kinase activity. Tyrosyl phosphorylation of these proteins and the level of the associated kinase activity are increased in the absence of SHP-1. Our data suggest that BIT and PIR-B recruit multiple signaling molecules to receptor complexes, where they are regulated by SHP-1 and/or SHP-2.

B cell antigen receptor-evoked calcium influx is enhanced in CD22-deficient B cell lines.

CD22 is a B cell membrane glycoprotein that, upon Ag receptor engagement, becomes rapidly tyrosyl phosphorylated and associates with several signaling molecules including Lyn, Syk, PLCgamma1, and the protein-tyrosine phosphatase, SHP-1. Two allelic forms of murine CD22 exist: CD22.1 is expressed in strains such as NZB and DBA/2, whereas CD22.2 is expressed in BALB/c and most other strains. WEHI-231 cells, which derive from a (BALB/c x NZB)F1 mouse, express one copy of each allele. Previous studies have proposed both positive and negative functions for CD22. We explored the role of CD22 in surface IgM Ag receptor signal transduction by examining signaling in three clonally independent WEHI-231 variants that have lost expression of the CD22.2 allele. This experimental design allowed us to assess the signaling functions of CD22 independent of its developmental role. These variants, which exhibit a 50% reduction of total surface CD22, are hyper-responsive to Ag receptor stimulation: several cellular proteins are hyperphosphorylated on tyrosyl residues and surface IgM-mediated calcium flux is markedly increased. Interestingly, the increased calcium response observed in CD22-deficient cells is due largely to enhanced calcium influx. Reconstitution of CD22 expression reduces these changes. The SHP-1/CD22 association is reduced in CD22-deficient cell lines and is restored by re-expression of CD22. Our results demonstrate that CD22 is a cell autonomous negative regulator of B cell Ag receptor signaling, and suggest that it regulates calcium entry via a mechanism downstream from or independent of calcium release from intracellular stores.

Protein-tyrosine phosphatase SHP-1 is dispensable for FcgammaRIIB-mediated inhibition of B cell antigen receptor activation.

The inhibitory Fc receptor, FcgammaRIIB, provides a signal that aborts B cell antigen receptor activation, blocking extracellular calcium influx. Because the protein-tyrosine phosphatase SHP-1 binds tyrosyl phosphorylated FcgammaRIIB and FcgammaRIIB-mediated inhibition is defective in motheaten (me/me) mice, which do not express SHP-1, it was proposed that SHP-1 mediates FcgammaRIIB signaling in B cells (D'Ambrosio, D., Hippen, K. L., Minskoff, S. A., Mellman, I., Pani, G., Siminovitch, K. A., and Cambier, J. C. (1995) Science 268, 293-297). However, SHP-1 is dispensable for FcgammaRIIB-mediated inhibition of FcepsilonRI signaling in mast cells (Ono, M., Bolland, S., Tempst, P., and Ravetch, J. V. (1996) Nature 383, 263-266), prompting us to re-examine the role of SHP-1 in FcgammaRIIB signaling in B cells. We generated immortalized sIgM+, FcgammaRIIB+ cell lines from me/me mice and normal littermates. Co-ligation of FcgammaRIIB and the sIgM antigen receptor inhibits calcium influx in both cell lines. Inhibition is reversed by preincubation with anti-FcgammaRIIB antibodies, indicating that it is mediated by FcgammaRIIB. The inositol 5' phosphatase SHIP is recruited to tyrosyl-phosphorylated FcgammaRIIB in both cell lines. FcgammaRIIB-mediated CD19 dephosphorylation also occurs in the presence or the absence of SHP-1. Our results establish that SHP-1 is dispensable for FcgammaRIIB-mediated inhibition of sIgM antigen receptor signaling.

Posttranslational acylation of the transferrin receptor in LSTRA cells with myristate, palmitate and stearate: evidence for distinct acyltransferases.

When incubated with [3H]myristate or [3H]palmitate, LSTRA cells, a murine T cell line, incorporated radiolabel into a protein of 95 kDa as analyzed by SDS-polyacrylamide gel electrophoresis. This dually acylated protein was identified as the transferrin receptor by immunoprecipitation with a monoclonal anti-transferrin receptor antibody. Acylation of the transferrin receptor was posttranslational and occurred via ester or thioester linkages. Analysis of radiolabeled transferrin receptor protein from [3H]myristate-labeled cells by acid hydrolysis followed by thin layer chromatography revealed the exclusive presence of [3H]myristate. Labeled transferrin receptor protein from [3H]palmitate-labeled cells contained predominantly [3H]stearate and smaller amounts of [3H]palmitate. This is in contrast to the protein-tyrosine kinase p56lck, which in [3H]palmitate-treated LSTRA cells, incorporated primarily [3H]palmitate. An analog of myristic acid, 5-nonanyloxyfuran-2-carboxylic acid, inhibited the incorporation of [3H]myristate, but not [3H]palmitate or [3H]stearate into transferrin receptor protein, suggesting that these acylation events are distinct. These studies indicate that the murine transferrin receptor is acylated posttranslationally with myristate, palmitate and stearate and suggest that more than one acyltransferase activity is responsible for its acylation.