Regulation of the association between PSTPIP and CD2 in murine T cells

Prominent in T cells and natural killer cells, CD2 binding protein 1 (CD2BP1) plays an important role in CD2-mediated adhesion and signal transduction. In the current study, we investigated CD2 and PSTPIP (proline, serine, threonine phosphatase interacting protein, murine homologue of CD2BP1) interactions in purified mouse splenic T cells. PSTPIP associated with CD2 in both resting and activated T cells. Following various stimuli, such as concanavalin A, anti-TCRbeta, anti-CD3epsilon, anti-CD3epsilon/phorbol myristate acetate (PMA), IL-2, or PMA/ionomycin, PSTPIP and CD2 expression, as well as their association, increased in a time-dependent fashion. While PSTPIP expression and CD2 expression were comparable across most groups, the PSTPIP-CD2 association stimulated by anti-CD3epsilon alone was significantly greater than with other stimuli. Stimulation by anti-CD3epsilon plus anti-CD28 induced even greater PSTPIP-CD2 association than anti-CD3epsilon treatment alone, indicating that CD28 initiated signals are involved in regulating this interaction. There was no direct association between CD3epsilon or CD28 and PSTPIP. Tyrosine phosphorylated PSTPIP bound poorly to CD2 compared to dephosphorylated PSTPIP, and protein tyrosine phosphatase was shown to affect both phosphorylation of PSTPIP and the CD2-PSTPIP association. In addition to CD2, PSTPIP associated with CD4, CD8, CD54, and CD62L. CD2 and CD4 ligation reciprocally regulated their association with PSTPIP. These findings indicate that T cell activation, particularly through the CD3 and CD28 signal transduction pathways, regulates PSTPIP-CD2 interactions. PSTPIP likely has additional broader effects through interactions with CD4, CD8, CD54, and CD62L, and this may influence T cell responses to antigen.

Association of pulmonary artery catheter use with in-hospital mortality

OBJECTIVE

To determine the association of pulmonary artery catheter (PAC) use with in-hospital mortality.

DESIGN

Prospective, observational study.

SETTING

The medical intensive care units (MICU) of two teaching hospitals.

METHODS

The study included 751 adults who were admitted to the MICU, excluding those who stayed for <24 hrs. Demographics and the worst Acute Physiology and Chronic Health Evaluation (APACHE) II score within the first 24 hrs of MICU admission were obtained. Daily logistic organ dysfunction system (LODS) scores were calculated. The associations of in-hospital mortality with the admission source, admission disease category, APACHE II scores, the worst LODS scores, mechanical ventilation, and PAC use were determined using chi-square, Mann-Whitney U, and multiple logistic regression analysis tests. p Values < 0.05 were considered significant.

RESULTS

Mean patient age was 52.6 +/- 17.1 yrs; 425 (57%) were male; 464 (62%) were African-American, 275 (37%) Caucasian, 6 (1%) Asian, and 6 (1%) Hispanic. PAC was used in 119/751 (16%). The median APACHE II and worst LODS scores were 19 and 4, respectively. The in-hospital mortality rate was 159/751 (21%). The median APACHE II score for survivors was 17.5, compared with 28.0 for nonsurvivors (p <.0001). The worst median LODS score was 4 for survivors, compared with 11 for nonsurvivors (p <.0001). Sixty-four (54%) of the 119 patients with PAC died, compared with 95 (15%) of the 632 without PAC (p <.0001). Multiple logistic regression analysis showed that higher APACHE II-predicted mortality rate (p =.0088) and worst daily LODS score (p <.0001) were associated with increased mortality. The admission source, admission disease category, PAC use, and mechanical ventilation were not associated with in-hospital mortality.

CONCLUSIONS

This study could not detect an association between PAC use and mortality. The APACHE II-predicted mortality rate and the development of multiple organ dysfunction were the main determinants of poor outcome in critically ill patients admitted to MICU.

CrkL is an adapter for Wiskott-Aldrich syndrome protein and Syk

Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia are caused by mutations of the WAS protein (WASP) gene. WASP may be involved in the regulation of podosome, an actin-rich dynamic cell adhesion structure formed by various types of cells. The molecular links between WASP and podosomes or other cell adhesion structures are unknown. Platelets express an SH2-SH3 adapter molecule, CrkL, that can directly associate with paxillin, which is localized in podosomes. The hypothesis that CrkL binds to WASP was, therefore, tested. Results from coprecipitation experiments using anti-CrkL and GST-fusion proteins suggest that CrkL binds to WASP through its SH3 domain and that the binding was not affected by WASP tyrosine phosphorylation. The binding of GST-fusion SH3 domain of PSTPIP1 in vitro was also not affected by WASP tyrosine phosphorylation, suggesting that the binding of the SH3 domains to WASP is not inhibited by tyrosine phosphorylation of WASP. Anti-CrkL also coprecipitates a 72-kd protein, which was identified as syk tyrosine kinase, critical for collagen induced-platelet activation. CrkL immunoprecipitates contain kinase-active syk, as evidenced by an in vitro kinase assay. Coprecipitation experiments using GST-fusion CrkL proteins suggest that both SH2 and SH3 domains of CrkL are involved in the binding of CrkL to syk. WASP, CrkL, syk, and paxillin-like Hic-5 incorporated to platelet cytoskeleton after platelet aggregation. Thus, CrkL is a novel molecular adapter for WASP and syk and may potentially transfer these molecules to the cytoskeleton through association with cytoskeletal proteins such as Hic-5.

Thalamic volumes in patients with first-episode schizophrenia

OBJECTIVE

The thalamus, a highly evolved sensory and motor gateway to the cortex, has been implicated in the pathophysiology of several illnesses, including schizophrenia. Several studies have suggested thalamic volume differences in patients with schizophrenia, although only a few studies have examined thalamic structure in new-onset patients.

METHOD

The authors used magnetic resonance imaging to measure thalamic volumes in previously untreated patients with first-episode schizophrenia (N=16) relative to those of healthy comparison subjects (N=25). The age range of the patients and comparison subjects was 15 to 45 years of age. Thalamic volumes in the right and left hemispheres were segmented and analyzed, both separately and as total thalamic volume, by a rater blind to clinical data. The thalamus was further segmented into regions that roughly reflected individual thalamic nuclei. Analysis of covariance was used to control for intracranial volume.

RESULTS

Right, left, and total thalamic volumes of the patients with schizophrenia were significantly smaller than those of the comparison subjects. Significantly smaller volumes were found in the left central medial subdivision of the patients as well as a smaller volume in the right central medial subdivision that approached significance. These regions primarily comprised the dorsomedial nucleus, a thalamic nucleus thought to be an important component of aberrant circuitry in schizophrenia. Significant volume differences were also seen in the left anterior, right anterior, and right posterior medial subdivisions.

CONCLUSIONS

These findings suggest significant thalamic volumetric differences between patients with newly diagnosed schizophrenia and healthy comparison subjects. Future analysis of individual thalamic nuclei may reveal important, specific relationships between thalamic abnormalities and schizophrenia.

Brain lithium concentrations in bipolar disorder patients: preliminary (7)Li magnetic resonance studies at 3 T

BACKGROUND

This study was conducted to investigate the feasibility of human brain (7)Li MRS investigations at a high magnetic field (3 T), and to further explore the relationship between brain and serum lithium measures in lithium-treated bipolar patients.

METHODS

Eight bipolar disorder type I patients (5 males, 3 females; mean age +/- SD = 33 +/- 9 years) were studied. A 3-T scanner, using a dual-tuned ((1)H and (7)Li) echoplanar imaging (EPI) compatible radiofrequency (RF) birdcage coil was used. (7)Li magnetic resonance spectroscopy (MRS) signal was acquired at the frequency of 49.64 MHz using an imaging selective in vivo spectroscopy (ISIS) sequence (TR = 15 sec, 128 averages), and quantitation was obtained in reference to an external standard.

RESULTS

The mean +/- SD oral lithium dose was 1265 +/- 442 mg/day, and the mean +/- SD 12-hour serum level was 0.69 +/- 0.19 mEq/L. The measured brain lithium concentrations varied from 0.23 to 0.55 mEq/L (mean +/- SD = 0.35 +/- 0.11 mEq/L). The brain-serum ratios varied from 0.30 to 0.80 (mean +/- SD = 0.52 +/- 0.16). Subjects on single daily doses of lithium at bedtime (n = 5) had higher brain-serum lithium ratios compared with those on twice-a-day schedules (n = 3) (0.61 +/- 0.12 and 0.37 +/- 0.07, respectively; Mann--Whitney U test, Z = -2.24, p =.03).

CONCLUSIONS

This study demonstrated for the first time the feasibility of (7)Li MRS human studies at 3 T. Future studies should examine a possible role for this methodology in investigations of lithium refractoriness and prediction of treatment outcome in bipolar patients.

Scabrous complexes with Notch to mediate boundary formation

The mechanisms that establish and sharpen pattern across epithelia are poorly understood. In the developing nervous system, the first pattern elements appear as 'proneural clusters' In the morphogenetic furrow of the immature Drosophila retina proneural clusters emerge in a wave as a patterned array of 6-10-cell groups, which are recognizable by expression of Atonal, a basic helix-loop-helix transcription factor that is required to establish and pattern the first cell fate. The establishment and subsequent patterning of Atonal expression requires activity of the signalling transmembrane receptor Notch. Here we present in vivo and biochemical evidence that the secreted protein Scabrous associates with Notch, and can stabilize Notch protein at the surface. The result is a regulation of Notch activity that sharpens proneural cluster boundaries and ensures establishment of single pioneer neurons.

Health status deterioration in patients with chronic obstructive pulmonary disease

This study examined health status decline in patients with chronic obstructive pulmonary disease (COPD). Data are from the Inhaled Steroids in Obstructive Lung Disease (ISOLDE) trial. After an 8-wk run-in, 751 patients (566 male), mean age 64 yr, were randomized to receive fluticasone propionate (FP) 500 microg twice daily (376 patients) or placebo (375 patients). Mean baseline postbronchodilator FEV1 was 50 +/- 15% predicted. Patients completed the St George's Respiratory Questionnaire (SGRQ) and the Short-Form 36 (SF-36) at baseline and every 6 mo for 3 yr. FEV1 and smoking status were assessed at baseline and at 3-mo intervals. A total of 387 (212 FP) patients completed the trial. All SGRQ components (p = 0.03 to 0.004) and Physical Function, Mental Health, Energy/ Vitality, and Physical Role Limitation scales of the SF-36 (p = 0.05 to 0.005) deteriorated faster in the placebo group. FEV1 and SGRQ scores correlated at baseline values (r = -0.25, p < 0.0001), as did change in FEV1 and change in SGRQ (Delta r = -0.24, p < 0.0001). At baseline values smokers had worse SGRQ Total, Symptoms, and Impacts scores than ex-smokers. This difference was maintained throughout the study. Smoking status did not influence the rate of decline in health status. The SGRQ Total scores of FP-treated patients took 59% longer than placebo to deteriorate by a clinically significant amount. We conclude that health status decline in moderate to severe COPD can be reduced by high-dose fluticasone.

Cytoskeletal protein PSTPIP1 directs the PEST-type protein tyrosine phosphatase to the c-Abl kinase to mediate Abl dephosphorylation

A search for c-Abl interacting proteins resulted in the recovery of PSTPIP1, originally identified as a binding protein of the PEST-type protein tyrosine phosphatases (PTP). PSTPIP1 was phosphorylated by c-Abl, and growth factor-induced PSTPIP1 phosphorylation was diminished in Abl null fibroblasts. PSTPIP1 was able to bridge c-Abl to the PEST-type PTPs. Several experiments suggest that the PEST-type PTPs negatively regulate c-Abl activity: c-Abl was hyperphosphorylated in PTP-PEST-deficient cells; disruption of the c-Abl-PSTPIP1-PEST-type PTP ternary complex by overexpression of PSTPIP1 mutants increased c-Abl phosphotyrosine content; and PDGF-induced c-Abl kinase activation was prolonged in PTP-PEST-deficient cells. Dephosphorylation of c-Abl by PEST-type PTP represents a novel mechanism by which c-Abl activity is regulated.

Interaction of the tumor suppressor PTEN/MMAC with a PDZ domain of MAGI3, a novel membrane-associated guanylate kinase

PTEN/MMAC is a phosphatase that is mutated in multiple human tumors. PTEN/MMAC dephosphorylates 3-phosphorylated phosphatidylinositol phosphates that activate AKT/protein kinase B (PKB) kinase activity. AKT/PKB is implicated in the inhibition of apoptosis, and cell lines and tumors with mutated PTEN/MMAC show increased AKT/PKB kinase activity and resistance to apoptosis. PTEN/MMAC contains a PDZ domain-binding site, and we show here that the phosphatase binds to a PDZ domain of membrane-associated guanylate kinase with inverted orientation (MAGI) 3, a novel inverted membrane-associated guanylate kinase that localizes to epithelial cell tight junctions. Importantly, MAGI3 and PTEN/MMAC cooperate to modulate the kinase activity of AKT/PKB. These data suggest that MAGI3 allows for the juxtaposition of PTEN/MMAC to phospholipid signaling pathways involved with cell survival.

N-Acetylaspartate concentration in the anterior cingulate of maltreated children and adolescents with PTSD

OBJECTIVE

Anterior cingulate dysfunction has been implicated in the pathophysiology of posttraumatic stress disorder (PTSD). The authors hypothesized that integrity of the anterior cingulate may be affected in childhood PTSD.

METHOD

Single voxel proton magnetic resonance spectroscopy (proton MRS) was used to measure the relative concentration of N-acetylaspartate and creatine, a marker of neural integrity, in the anterior cingulate of 11 children and adolescents who met DSM-IV criteria for PTSD secondary to maltreatment and 11 healthy matched comparison subjects.

RESULTS

The ratio of N-acetylaspartate to creatine was significantly lower in the maltreated subjects with PTSD than in the comparison subjects.

CONCLUSIONS

The lower N-acetylaspartate/creatine ratio in subjects with PTSD suggests that anterior cingulate neuronal metabolism may be altered in childhood PTSD.

Randomised, double blind, placebo controlled study of fluticasone propionate in patients with moderate to severe chronic obstructive pulmonary disease: the ISOLDE trial

OBJECTIVES

To determine the effect of long term inhaled corticosteroids on lung function, exacerbations, and health status in patients with moderate to severe chronic obstructive pulmonary disease.

DESIGN

Double blind, placebo controlled study.

SETTING

Eighteen UK hospitals.

PARTICIPANTS

751 men and women aged between 40 and 75 years with mean forced expiratory volume in one second (FEV(1)) 50% of predicted normal.

INTERVENTIONS

Inhaled fluticasone propionate 500 microgram twice daily from a metered dose inhaler or identical placebo.

MAIN OUTCOME MEASURES

Efficacy measures: rate of decline in FEV(1) after the bronchodilator and in health status, frequency of exacerbations, respiratory withdrawals. Safety measures: morning serum cortisol concentration, incidence of adverse events.

RESULTS

There was no significant difference in the annual rate of decline in FEV(1 )(P=0.16). Mean FEV(1) after bronchodilator remained significantly higher throughout the study with fluticasone propionate compared with placebo (P<0.001). Median exacerbation rate was reduced by 25% from 1.32 a year on placebo to 0.99 a year on with fluticasone propionate (P=0.026). Health status deteriorated by 3.2 units a year on placebo and 2.0 units a year on fluticasone propionate (P=0.0043). Withdrawals because of respiratory disease not related to malignancy were higher in the placebo group (25% v 19%, P=0.034).

CONCLUSIONS

Fluticasone propionate 500 microgram twice daily did not affect the rate of decline in FEV(1) but did produce a small increase in FEV(1). Patients on fluticasone propionate had fewer exacerbations and a slower decline in health status. These improvements in clinical outcomes support the use of this treatment in patients with moderate to severe chronic obstructive pulmonary disease.

Pressure relieving interventions for preventing and treating diabetic foot ulcers

BACKGROUND

Foot ulceration is thought to affect 15% of all people with diabetes at some time during their life.

OBJECTIVES

To assess the effectiveness of pressure relieving interventions in the prevention and treatment of diabetic foot ulcers.

SEARCH STRATEGY

Searches of 19 databases, hand searching of journals, bibliographies and identification of unpublished work by written communication with recognised experts in the diabetic foot.

SELECTION CRITERIA

Randomised controlled trials evaluating pressure relieving interventions either in the prevention or the treatment of diabetic foot ulcers. There was no restriction on articles/trials based on language or publication status.

DATA COLLECTION AND ANALYSIS

Data extraction and assessment of study quality was undertaken by two reviewers independently. Each trial was analysed separately, no pooling of results was possible due to the difference in patients, comparisons and outcomes.

MAIN RESULTS

Prevention 4 RCTs of pressure relieving interventions were identified. Interventions for the prevention of diabetic foot ulcers indicated that in-shoe orthotics are of benefit. The relative merits of different in-shoe orthotics are unclear; cushioning and pressure redistribution appear of equal benefit. Other pressure relieving interventions such as running shoes have not been adequately evaluated and removable casts (Scotchcast or Hope) or foam inlays do not appear to have been evaluated at all in randomised controlled studies. Treatment 1 RCT of total contact casting indicated that it was effective in the treatment of diabetic ulcers although the evidence was limited.

REVIEWER'S CONCLUSIONS

Prevention There is limited evidence of the effectiveness of orthotic interventions over removal of callus. There is some evidence evaluating the relative effectiveness of two types orthotic devices. There is very limited evidence of the effectiveness of therapeutic shoes. Treatment There is very limited evidence of the effectiveness of total contact casts in the treatment of diabetic foot ulcers. Overall there is a need to measure the effectiveness of the range of pressure relieving interventions for the prevention and treatment of diabetic foot ulcers as there is a small amount of poor quality research in this area.

The animal scientist in a changing society

Despite the lack of any credible scientific evidence to oppose the use of animal performance-enhancing agents, acceptance of performance enhancers seems no closer than it was a decade ago--at least among the European Community and its major trading partners. Consumers are suspicious of new technologies, and politicians are wary of legalizing growth promoters when the relative price of animal products has never been cheaper. Among the factors that have recently re-fuelled consumer concerns over farming methods are: bovine spongiform encephalopathy, cloning of farm animals, and genetic manipulation of crops. Meanwhile, politicians try to balance the interests of the environmentalist, farming, and welfare lobbies with the politico-economic realities of an expanding European Community and the demands of the GATT agreement. In the United States, where corporate influence over political actions is more overtly established than in Europe, some new technologies have been introduced. This has further antagonized many consumers. As scientists with a direct interest in animal performance enhancers, we need to re-assess our positions--if for no other reason than to protect our research (and personal) incomes. We could probably better protect our own interests--and those of the farming community--if we raised our eyes from the microscope to look at the wider view. There are two challenges for animal production scientists: to identify truly acceptable ways of enhancing animal performance and to be highly active in bringing scientific consensus to the attention of both the public and the political establishments.

UFT/oral calcium folinate plus radiation in pancreatic cancer

A phase I, single-center, open-label, dose-escalation study (University of Alabama [UAB] 9614) has been undertaken to evaluate the feasibility and safety of uracil and tegafur (in a molar ratio of 4:1 [UFT]) plus oral calcium folinate (Orzel) plus radiotherapy in patients with pancreatic cancer. A total of 11 patients with a median age of 59 years have been treated for 35 days with 150 mg/m2/day of UFT and 90 mg/day of oral calcium folinate, divided into three daily doses. Radiotherapy began on day 1, to a total dose of 45 Gy at 1.8 Gy per day (for approximately 5 weeks). Dose escalation of UFT will be performed until the maximum tolerated dose is defined. Overall, therapy has been well tolerated and the maximum tolerated dose has not yet been reached.

Investigation into the role of the response regulator NtrC in the metabolism and virulence of Brucella suis

During infection, Brucella species have to adapt to a range of different environments. Environmental sensing in bacteria often involves the concerted action of two-component regulatory systems consisting of sensor and response regulator components. In this study, we identified, cloned and sequenced four independent response regulator gene fragments from Brucella melitensis. One amplified gene fragment showed nearly 90% identity to the response regulator subfamily of NtrC transcriptional activators, and further analysis revealed the presence of an adjacent gene encoding the sensor protein NtrB. The NtrBC two-component regulatory system has been shown to play varying roles in nitrogen metabolism and potentially in virulence in other bacterial species. A B. suis ntrC isogenic mutant was constructed which showed no significant differences in growth rates compared to the wild-type strain when grown at different temperatures in vitro. However, the mutant exhibited a reduction in metabolic activity in the presence of many amino acids. The mutation did not affect survival or multiplication of B. suis in macrophages, but during the initial stages of infection in the murine brucellosis model, the ntrC mutant showed a reduced ability to multiply rapidly in splenic tissue.

Chemoradiotherapy of locally advanced esophageal cancer: long-term follow-up of a prospective randomized trial (RTOG 85-01). Radiation Therapy Oncology Group

CONTEXT

Carcinoma of the esophagus traditionally has been treated by surgery or radiation therapy (RT), but 5-year overall survival rates have been only 5% to 10%. We previously reported results of a study conducted from January 1986 to April 1990 of combined chemotherapy and RT vs RT alone when an interim analysis revealed significant benefit for combined therapy.

OBJECTIVE

To report the long-term outcomes of a previously reported trial designed to determine if adding chemotherapy during RT improves the survival rate of patients with esophageal carcinoma.

DESIGN

Randomized controlled trial conducted 1985 to 1990 with follow-up of at least 5 years, followed by a prospective cohort study conducted between May 1990 and April 1991.

SETTING

Multi-institution participation, ranging from tertiary academic referral centers to general community practices.

PATIENTS

Patients had squamous cell or adenocarcinoma of the esophagus, T1-3 N0-1 M0, adequate renal and bone marrow reserve, and a Karnofsky score of at least 50. Interventions Combined modality therapy (n = 134): 50 Gy in 25 fractions over 5 weeks, plus cisplatin intravenously on the first day of weeks 1, 5, 8, and 11, and fluorouracil, 1 g/m2 per day by continuous infusion on the first 4 days of weeks 1, 5, 8, and 11. In the randomized study, combined therapy was compared with RT only (n = 62): 64 Gy in 32 fractions over 6.4 weeks.

MAIN OUTCOME MEASURES

Overall survival, patterns of failure, and toxic effects.

RESULTS

Combined therapy significantly increased overall survival compared with RT alone. In the randomized part of the trial, at 5 years of follow-up the overall survival for combined therapy was 26% (95% confidence interval [CI], 15%-37%) compared with 0% following RT. In the succeeding nonrandomized part, combined therapy produced a 5-year overall survival of 14% (95% CI, 6%-23%). Persistence of disease (despite therapy) was the most common mode of treatment failure; however, it was less common in the groups receiving combined therapy (34/130 [26%]) than in the group treated with RT only (23/62 [37%]). Severe acute toxic effects also were greater in the combined therapy groups. There were no significant differences in severe late toxic effects between the groups. However, chemotherapy could be administered as planned in only 89 (68%) of 130 patients (10% had life-threatening toxic effects with combined therapy vs 2% in the RT only group).

CONCLUSION

Combined therapy increases the survival of patients who have squamous cell or adenocarcinoma of the esophagus, T1-3 N0-1 M0, compared with RT alone.

Monoclonal antibodies as potentiators of radiotherapy and chemotherapy in the management of head and neck cancer

The overall survival of patients with squamous cell cancer of the head and neck has not significantly improved over the past 2 decades. Preclinical studies suggest that combining a monoclonal antibody to the epidermal growth factor receptor with irradiation or chemotherapy agents active in squamous cell cancer of the head and neck could increase treatment efficacy. Completed phase I studies have shown these combinations to be both feasible and tolerable. Phase III studies are now beginning to establish firmly the efficacy of this innovative new approach.

Multimodality therapy of patients with locally advanced squamous cell cancer of the head and neck: preliminary results of two pilot trials using paclitaxel and cisplatin

Chemotherapy has been integrated into the initial treatment of patients with locally advanced squamous cell cancer of the head and neck to improve locoregional control and survival. Two strategies for improving these outcomes are the use of new, potentially more effective drugs either with concurrent radiotherapy or as induction regimens. Because of its inherent activity against squamous cell cancer of the head and neck and its radiation-sensitizing properties, paclitaxel may be a valuable agent in the treatment of this patient population. We describe the preliminary results of two trials that evaluated the combination of paclitaxel and cisplatin in patients with locally advanced disease: a phase I trial of weekly paclitaxel and cisplatin with concurrent postoperative radiation therapy in patients with high-risk disease and a phase I/II trial of paclitaxel as a 96-hour infusion in combination with cisplatin as induction therapy. These studies identified tolerable doses of paclitaxel and cisplatin administered in these settings, with apparent clinical activity. These trials formed the basis for subsequent evaluation of induction paclitaxel and cisplatin followed by definitive radiotherapy and concurrent weekly paclitaxel and cisplatin plus radiotherapy.

Protein tyrosine phosphatase-PEST regulates focal adhesion disassembly, migration, and cytokinesis in fibroblasts

In this article, we show that, in transfected COS-1 cells, protein tyrosine phosphatase (PTP)-PEST translocates to the membrane periphery following stimulation by the extracellular matrix protein fibronectin. When plated on fibronectin, PTP-PEST (-/-) fibroblasts display a strong defect in motility. 3 h after plating on fibronectin, the number and size of vinculin containing focal adhesions were greatly increased in the homozygous PTP-PEST mutant cells as compared with heterozygous cells. This phenomenon appears to be due in part to a constitutive increase in tyrosine phosphorylation of p130(CAS), a known PTP-PEST substrate, paxillin, which associates with PTP-PEST in vitro, and focal adhesion kinase (FAK). Another effect of this constitutive hyperphosphorylation, consistent with the focal adhesion regulation defect, is that (-/-) cells spread faster than the control cell line when plated on fibronectin. In the PTP-PEST (-/-) cells, an increase in affinity for the SH2 domains of Src and Crk towards p130(CAS) was also observed. In (-/-) cells, we found a significant increase in the level of tyrosine phosphorylation of PSTPIP, a cleavage furrow-associated protein that interacts physically with all PEST family members. An effect of PSTPIP hyperphosphorylation appears to be that some cells remain attached at the site of the cleavage furrow for an extended period of time. In conclusion, our data suggest PTP-PEST plays a dual role in cell cytoskeleton organization, by promoting the turnover of focal adhesions required for cell migration, and by directly or indirectly regulating the proline, serine, threonine phosphatase interacting protein (PSTPIP) tyrosine phosphorylation level which may be involved in regulating cleavage furrow formation or disassembly during normal cell division.

Why do foot ulcers recur in diabetic patients?

AIM

To investigate factors predisposing to recurrent foot ulceration in patients with diabetes mellitus.

METHODS

Two groups of patients who had attended a specialist Diabetes Foot Centre were assessed: relapsers (n = 26), whose foot ulceration had recurred at least twice, and nonrelapsers (n = 25), whose initial ulcer had not recurred for at least 2 years.

RESULTS

In the relapser group 10/26 patients waited at least 24 h before reporting symptoms compared with only 2/25 in the nonrelapser group (P < 0.05). Vibration perception threshold (volts) was 38 +/- 12 (mean +/- SD) in relapsers compared with 25 +/- 13 in nonrelapsers (P < 0.005). Cold perception threshold (degrees C) was 9.1 +/- 4.6 in relapsers compared with 5.1 +/- 3.5 in nonrelapsers (P<0.005). HbA1c (%) was significantly raised at 8.5 +/- 1.7 in relapsers compared with 7.6 +/- 1.2 in nonrelapsers (P = 0.03). Alcohol intake was 0.5 (median, interquartile range 0-2) units per day in relapsers compared with 0.0 (median, interquartile range 0-0.25) units in nonrelapsers (P = 0.04). Smoking habits, housing conditions, visual acuity, threshold for warm perception and the Doppler pressure index were not significantly different in the two groups.

CONCLUSIONS

Patients who develop recurrent foot ulceration delay in reporting symptoms, when compared with diabetic patients whose foot ulceration does not recur. The relapsers also have evidence of poorer glycaemic control, more neuropathy and increased alcohol intake.