The osteoclast functional antigen, implicated in the regulation of bone resorption, is biochemically related to the vitronectin receptor

We have defined the structure of the Osteoclast Functional Antigen (OFA) by immunological and biochemical means. OFA is an abundant surface antigen in human and animal osteoclasts and has been characterized previously by monoclonal antibodies 13C2 and 23C6, one of which mimicks the inhibitory activity of calcitonin on osteoclastic bone resorption. By the following criteria we show that OFA is a member of the integrin family of extracellular matrix receptors and is identical, or at least highly related, to the vitronectin receptor (VNR) previously isolated from placenta and melanoma cells. Immunoprecipitation analysis demonstrates that OFA from osteoclasts and a monkey kidney cell line Vero is a heterodimeric molecule of 140 kD (alpha chain) and 85 kD (beta chain) under nonreducing conditions; on reduction at least one low molecular mass (alpha') species (of approximately 30-kD size) is released, resulting in a 120/100-kD dimer. Immunoblots of OFA isolated from osteoclasts and Vero cells and VNR purified from placenta and probed with heterosera to OFA and monoclonal antibodies to platelet gp111a (VNR beta chain) show immunological cross-reactivity between the alpha chains of OFA and VNR and the use of gp111a as a beta chain by both. OFA from Vero cells binds to an Arg-Gly-Asp containing peptide (GRGDSPPK) isolating a heterodimer recognized by anti-OFA monoclonal antibodies, 13C2 and 23C6. Immunohistochemical analysis showed a similar tissue distribution in humans for the antigen recognized by anti-OFA antibodies, a monoclonal antibody, LM142, raised to melanoma VNR, polyclonal antibodies to the placental VNR and a monoclonal antibody to the presumptive VNR beta chain, platelet glycoprotein 111a. Finally, NH2 terminal amino acid sequencing showed that the amino-terminus of the monkey alpha chain was identical in the 12 assigned residues to that of human VNR alpha chain. The beta chain sequence of OFA differed at least 1 (and up to 4) positions from platelet gp111a (VNR beta) in the first 18 amino acids sequenced. These, and other, data provide the first indication of a function for the VNR and suggest that cell-cell and cell-extracellular matrix interactions involving integrins may play an important role in bone physiology.

Gas chromatographic, mass spectrometric and stable carbon isotopic investigations of organic residues of plant oils and animal fats employed as illuminants in archaeological lamps from Egypt

Man's use of illuminants in lamps or as torches to extend the working day and range of environments accessible to him would have been a major technological advance in human civilisation. The most obvious evidence for this in the archaeological record comes from pottery and stone vessels showing sooting due to the use of a wick in conjunction with a lipid-based fuel or illuminant. A wide range of potential fuels would have been exploited depending upon availability and burning requirements. Reported herein are the results of chemical investigations of a number of lamps recovered from excavations of the site of Qasr Ibrim, Egypt. Gas chromatographic, mass spectrometric and stable carbon isotopic analyses of both free (solvent extractable) and 'bound'(released from solvent extracted pottery by base treatment) lipids have revealed a wide range of saturated fatty acids, hydroxy fatty acids and alpha, omega-dicarboxylic acids. Examination of the distributions of compounds and comparisons with the fatty acid compositions of modern plant oils have allowed a range of fats and oils to be recognised. Specific illuminants identified include Brassicaceae (Cruciferae) seed oil (most likely radish oil, Raphanus sativus), castor oil (from Ricinus communis), animal fat, with less diagnostic distributions and delta(13)C values being consistent with low stearic acid plant oils, such as linseed (Linum usitatissimum) or sesame (Sesamum indicum) oils. The identifications of the various oils and fats are supported by parallel investigations of illuminant residues produced by burning various oils in replica pottery lamps. The findings are entirely consistent with the classical writers including Strabo, Pliny and Theophrastrus.

Unusual abscess patterns following dropped gallstones during laparoscopic cholecystectomy

BACKGROUND

Laparoscopic cholecystectomy has become the standard treatment for symptomatic cholelithiasis. Numerous clinical trials have deemed it a safe procedure, regardless of the known increased risk of bile duct injury. However, the consequences and incidence of less well-known complications are still being addressed.

METHODS

Between 1993 and 1995, 1,130 laparoscopic cholecystectomies were performed at two major metropolitan medical centers. Of these patients, we know of 3 (0.3%) who subsequently developed abscesses as a consequence of dropped stones during the laparoscopic cholecystectomy. One additional patient who underwent prior laparoscopic cholecystectomy at another institution developed late infection as well.

RESULTS

All 4 patients developed late purulent abscesses that ultimately required open surgical drainage, and 1 patient developed trocar site "tumor" masses that were secondary to inflammatory tissue around gallstone fragments. All patients were successfully treated by surgical drainage, stone removal, and antibiotics. Trocar site inflammatory masses required excision only. Significant costs were involved in the diagnosis, management, and duration of therapy for these problems.

CONCLUSIONS

This experience closely resembles that of other centers and points out the existence of a late postoperative complication following laparoscopic cholecystectomy that was rarely encountered with open cholecystectomy. Strategies for avoiding this problem are discussed. Whether dropped stones are an indication for conversion to open cholecystectomy remains unclear. Thorough irrigation at time of laparoscopic cholecystectomy with or without placement of a drain in the subhepatic space does not prevent this complication.

Influence of age, renal and liver impairment on the pharmacokinetics of risperidone in man

The pharmacokinetics of the antipsychotic agent risperidone were investigated in healthy young and elderly subjects, cirrhotic patients and patients with moderate and severe renal insufficiency. In a comparative trial, a single oral 1-mg dose was administered to fasting subjects. Plasma and urine concentrations of the parent compound risperidone and the active moiety (i.e. risperidone plus 9-hydroxy-risperidone) were measured by radioimmunoassays. No or only small changes in plasma protein binding were observed in hepatic and renal disease, whereas the protein binding was not influenced by aging. The inter-individual variability in plasma concentrations of the active moiety was much less than the variability in plasma concentrations of risperidone. Three out of six subjects, behaving like poor metabolizers, were on medication (thiethylperazine, amitriptyline, metoprolol) that may inhibit risperidone metabolism by CYP2D6 (debrisoquine 4-hydroxylase). The pharmacokinetics of risperidone in elderly and cirrhotic patients were comparable to those in young subjects, whereas total oral clearance was reduced in renal disease patients. The elimination rate and clearance of 9-hydroxy-risperidone was reduced in elderly and renal disease patients because of a diminished creatinine clearance. The CL(oral) of the active moiety, which is primarily 9-hydroxy-risperidone, was reduced by about 30% in the elderly and by about 50% in renal disease patients. In addition, the t1/2 of the active moiety was prolonged (19 h in young subjects versus about 25 h in elderly and renal disease patients). Based upon the pharmacokinetics of the active moiety, a dose reduction and a cautious dose titration is advised in the elderly and in patients with renal disease. In cirrhotic patients, the single-dose pharmacokinetics were comparable to those in healthy young subjects.

Hepatic cryotherapy: double-freeze cycles achieve greater hepatocellular injury in man

Hepatic cryotherapy is a relatively new technique used to treat both primary and secondary tumors. This paper concerns the changes in serum aspartate transaminase (AST) in 45 patients following both single and double freeze with partial thaw cycles. There was considerable elevation in serum AST, greatest on the day of operation, and there was a significantly higher peak AST following the double-freeze cycles (1159; SE, 117.5) compared with single-freeze/thaw procedures (437; SE, 61.7). This finding indicates greater hepatocellular disruption which may be important both in planning clinical hepatic cryosurgery to achieve adequate destruction and also to avoid the morbidity of the cryoshock phenomenon.

Smooth muscle cell matrix metalloproteinase production is stimulated via alpha(v)beta(3) integrin

This study tests the hypothesis that alpha(v)beta(3) integrin receptors play a critical role in smooth muscle cell (SMC) migration after arterial injury and facilitate migration through the upregulation of matrix metalloproteinase (MMP) activity. We showed that beta(3) integrin mRNA was upregulated by SMCs in the balloon-injured rat carotid artery in coincidence with MMP-1 expression and early SMC migration. Treatment with the beta(3) integrin-blocking antibody F11 significantly decreased SMC migration into the intima at 4 days after injury, from 110.8+/-30.8 cells/mm(2) in control rats to 10.29+/-7.03 cells/mm(2) in F11-treated rats (P=0.008). By contrast, there was no effect on medial SMC proliferation or on medial SMC number in the carotid artery at 4 days. In vitro, we found that human newborn SMCs produced MMP-1 but that adult SMCs did not. This was possibly due to the fact that newborn SMCs expressed alpha(v)beta(3) integrin receptors, whereas adult SMCs did not. Stimulation of newborn (alpha(v)beta(3)+) SMCs with osteopontin, a matrix ligand for alpha(v)beta(3), increased MMP-1 production from 114.4+/-35.8 ng/mL at 0 nmol/L osteopontin to 232.5+/-57.5 ng/mL at 100 nmol/L osteopontin. Finally, we showed that stimulation of newborn SMCs with platelet-derived growth factor-BB and osteopontin together increased the SMC production of MMP-9. Thus, our results support the hypothesis that SMC alpha(v)beta(3) integrin receptors play an important role in regulating migration by stimulating SMC MMP production.

Survival advantage of stentless aortic bioprostheses

BACKGROUND

Bioprostheses (BPs) are used to avoid anticoagulation after aortic valve replacement (AVR) in patients over 65 years of age. Stentless BPs offer established hemodynamic benefits. We sought to determine whether these advantages translate into improved survival.

METHODS

Between 1993 and 1997, follow-up data (for Food and Drug Administration submission) were collected prospectively for 160 consecutive, unselected hospital survivors who received the Freestyle valve (FS). Equivalent data were collected for 247 Carpentier-Edwards (CE) porcine xenograft patients. Detailed comparative statistical analysis was used to compare events and survival between the groups. Follow-up was 100% complete for the FS (5.2 years maximum; mean 3.2+/-1.0 years) group and 98% (7.2 years maximum; mean 3.8+/-2.0 years) for CE.

RESULTS

The groups were well matched in age (FS, 73+/-6 years; CE, 74+/-6 years), gender (FS, 58% male; CE, 62% male), ventricular function, and number of patients requiring coronary grafts (FS, 41%; CE, 37%). Actuarial survival at 5 years was 84% for FS versus 69% for CE (p = 0.023 Kaplan Meier, p = 0.009 Cox). Annual mortality rates were 3.6% for FS versus 7.1% for CE (p = 0.001). Thromboembolic rate was 0.8% per year for FS and 2.4% for CE (p = 0.024) without a difference in cardiac rhythm. Incidence of nonstructural dysfunction (paravalvular leak) was 0.2% for FS versus 1.3% for CE (p = 0.020).

CONCLUSIONS

By 5 years, the stentless valve patients had improved survival and reduced adverse events. Though differences in durability are yet to be proved, our findings support the use of stentless bioprostheses in this age group.

ADAM gene expression and regulation during human osteoclast formation

In this study, we identified the expression and the regulation of ADAM members (a disintegrin and metalloprotease) at both gene and protein levels during human osteoclast differentiation and activity. Human peripheral blood monocytes (HPBMC) treated with M-CSF and RANKL were used as an in vitro fusion model. In parallel, we used human osteoclastoma (OCL) tumor as a source of mature osteoclasts, and human osteoblastic cells as a control representing nonfusing and non-resorbing bone cells. RT-PCR using ADAM-specific primers enabled us to identify the expression of ADAM 8, 9, 10, 15, 17, and 28 in both osteoclasts and osteoblasts. Using primers specific for each ADAM 12 isoform (L and S), we observed a strong signal for both forms (ADAM 12L and ADAM 12S) in osteoblastic cells, while only ADAM 12S was detectable in HPBMC-derived osteoclasts and osteoclastoma. Gene regulation was studied using real-time PCR analysis performed during HPBMC differentiation; this showed a progressive increase of ADAM 12 mRNA level from day 1 to 8 of the culture, while at around day 9, ADAM 12 mRNA level decreased 2-fold. We also showed that ADAM 8, ADAM 17, and ADAM 28 decreased according to the stage of HPBMC differentiation or fusion. ADAM 10 was unaltered during cell fusion. However, confocal immunolocalization showed that ADAM 10 protein re-localized from the nuclei and cytoplasm to the plasma membrane during culture and to the ruffled border in resorbing cells. The same re-localization process was observed using an ADAM 12S-specific antibody during HPBMC differentiation. Between days 12 and 14, ADAM 12 co-localized with the F-actin ring, and at day 15, a strong signal was also present in ruffled border or sealing zone area of osteoclasts. Our results describe the expression and regulation of various ADAMs in human bone cells and the selective expression of ADAM 12L in osteoblasts. Our gene regulation and protein localization studies suggest a function for ADAM 10 and ADAM 12S in the formation of osteoclasts from HPBMC and resorption activity.

Renal dysfunction does not alter the pharmacokinetics or LDL-cholesterol reduction of atorvastatin

The objective of this study was to determine the effects of renal dysfunction on the steady-state pharmacokinetics and pharmacodynamics of atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor. Nineteen subjects with calculated creatinine clearances ranging from 13 mL/min to 143 mL/min were administered 10 mg atorvastatin daily for 2 weeks. Pharmacokinetic parameters and lipid responses were analyzed by regression on calculated creatinine clearance. Correlations between steady-state atorvastatin pharmacokinetic or pharmacodynamic parameters and creatinine clearance were weak and, in general, did not achieve statistical significance. Although the elimination rate constant, lambda z (0.579), was significantly correlated with creatinine clearance, neither maximum plasma concentration (Cmax, -0.361) nor oral clearance (Cl/F, 0.306) were; thus, steady-state exposure is not altered. Renal impairment has no significant effect on pharmacodynamics and pharmacokinetics of atorvastatin.

Opinions and experiences in general practice on osteoporosis prevention, diagnosis and management

We determined to survey the general practice population regarding their attitudes to and knowledge of osteoporosis as a baseline prior to publication of national guidelines for the management of osteoporosis. All 2515 general practitioners registered in the 10 Health Authorities of the North Thames region, London, UK were surveyed by a postal questionnaire. Responses relating to epidemiology, public health and education on osteoporosis were analyzed. The overall response was 1153 (46%). General practitioners who responded were younger, predominantly female and in group practice. There is considerable awareness of the importance of preventing osteoporosis. General practitioners are active in identifying groups at risk, particularly those who are aged 40 years and older. A prevention strategy for osteoporosis is viewed as effective. However, two thirds of general practitioners remain unconvinced about the efficacy of drug therapy. Education on osteoporosis is considered inadequate. General practitioners would welcome further information on management issues and access to osteoporosis services. In conclusion, educational initiatives will be important both at undergraduate and postgraduate levels to increase awareness and knowledge of osteoporosis. General practitioners are aware of the public health impact of this condition and express a preference for educational material of direct relevance to the care of their patients. Therefore better cooperation between primary and secondary care should lead to ways of breaking down barriers to change in clinical practice and promoting fully integrated care of patients with osteoporosis.

Cryotherapy of liver tumours--a practical guide

The use of cryotherapy for the treatment of some unresectable liver tumours has been clearly established as a therapeutic option. Intra-operative ultrasound has enhanced the process by enabling the surgeon to identify hepatic lesions and to allow visualisation of the freezing process to ensure that the cryolesion will include the tumour mass. The purpose of this paper is to provide a practical guide to surgeons who wish to perform cryotherapy of liver tumours. Patient selection and anaesthetic considerations are important. The surgeon should be able to deal with the complications of cryotherapy, particularly the intra-operative haemorrhage which may arise from cracking of the hepatic parenchyma as the iceball thaws. Follow-up is based on tumour marker assay and imaging of the liver and repeat cryotherapy can be considered for selected cases.

High dose cytosine arabinoside in the initial treatment of adults with acute lymphoblastic leukaemia

In a study conducted at St Bartholomew's Hospital between 1972 and 1982, using moderately intensive therapy (OPAL/HEAV'D), a low blast count at presentation (less than 10 x 10(9) 1(-1)) and common ALL (C-ALL) phenotype correlated favourably with duration of remission. Fifty-four patients (age range 15-57, median 32) subsequently received a modification of the previous treatment programme which included high-dose ara-C 2 g m-2 b.d. for 6 days as cycle 3 (OPAL + HD ARA-C). CR was achieved in 36/54 (67%) patients, response correlating favourably with younger age (15-30 years vs 31-57 years, P = 0.02). Three patients died in CR. Overall, there was no difference in survival or remission duration between patients who received high dose ara-C and those in the control group. However, in contrast to the early results, there was a reversal in the relevance of the prognostic factors with a trend in favour of high blast count (greater than 10 x 10(9) 1(-1)) and T-cell phenotype in terms of remission duration. Moreover, comparison of duration of remission for the previously defined prognostic groups according to therapy suggests that the prognosis of patients with 'high risk' disease (T, B, null ALL or high blast count) is improved with more intensive therapy. In contrast, those with 'low risk' disease (C-ALL and low blast count) have a better prognosis with less intensive therapy. These observations confirm those of others and allow for individualization of therapy on the basis of pre-treatment variables.

Blocking monoclonal antibodies to alpha V beta 3 integrin: a unique epitope of alpha V beta 3 integrin is present on human osteoclasts

Integrins are a family of cell surface glycoproteins that promote cell adhesion. The integrin alpha V beta 3, vitronectin receptor, is a major integrin expressed by osteoclasts. To further investigate the role of alpha V beta 3 in cell adhesion, we generated and characterized monoclonal antibodies to alpha V beta 3 by immunizing BALB/c mice with purified alpha V beta 3 protein. Three monoclonal antibodies (mAbs), 9D4.9.1, 9G2.1.3, and 10C4.1.3, from a total of more than 1100 positive cultures which bound alpha V beta 3, were characterized extensively: mAbs 9G2.1.3 and 10C4.1.3 recognize the alpha V beta 3 complex whereas mAb 9D4.9.1 reacts with the beta 3-chain shared between the alpha V beta 3 complex and gpIIbIIIa. Further epitope mapping using flow microfluorometry analysis and histochemical staining of various tissues showed that 9D4.9.1 and 10C4.1.3 recognized distinct epitopes. Ligand-binding studies using cell-bound and purified alpha V beta 3 demonstrated that all three mAbs blocked fibrinogen binding. Vitronectin binding was blocked by mAb 9D4.9.1 and, less effectively, by mAb 10C4.1.3; mAb 9G2.1.3 was without effect. All three mAbs recognized osteoclasts from human tissues; mAb 9G2.1.3 also stained osteoclasts from a wide range of nonhuman species. Monoclonal antibodies 9D4.9.1 and 9G2.1.3 bound to a panel of cultured cell lines and various tissues. In contrast, mAb 10C4.1.3 bound only weakly or not at all to tissues expressing alpha V beta 3 with the exception of osteoclasts. Thus, mAb 10C4.1.3 showed a very narrow tissue specificity being restricted to high-level expression on human osteoclasts.

A method for evaluating computer programs for electrocardiographic interpretation. 3. Reproducibility testing and the sources of program errors

A simple method for testing reproducibility in ECG computer program performance results from using two digital representations of the same analog ECG tracing. Each digital representation is separated from the other by one millisecond in time. When the digital representations are processed by the Mayo Clinic program (1968), the diagnostic statements are identically reproduced in only 60% of 33 tracings. When the method is applied to version D of the PHS program and to the newly released IBM program of 1973, identical reproducibility is 43.3% and 76.0%, respectively, of 217 tracings. After analog filtering these figures are improved to 49.8% and 79.7%, respectively. These results show that reproducibility is most affected by a program's algorithms for pattern recognition, measurement, consistency checking, and noise handling. Reproducibility is less affected by attenuation of high frequency noise at the analog level. The relationship of reproducibility to program error rate in previous studies is discussed. Hence poor performance on this test obviates the need for a more time-consuming clinical evaluation. The need for human overview and quality checking is re-emphasized.

The pharmacokinetics of ziprasidone in subjects with normal and impaired renal function

AIMS

To assess whether renal impairment influences the pharmacokinetics of ziprasidone, and to determine whether ziprasidone is cleared via haemodialysis.

METHODS

Thirty-nine subjects with varying degrees of renal impairment were enrolled into an open-label, multicentre, multiple-dose study and assigned to four groups according to their renal function: normal (group 1, creatinine clearance > 70 ml min(-1); mildly impaired (group 2, creatinine clearance 30-60 ml min(-1); moderately impaired (group 3, creatinine clearance 10-29 ml min(-1), and severely impaired (group 4, requiring haemodialysis three times-a-week). Subjects received ziprasidone 40 mg day(-1), given orally with food, as two divided daily doses for 7 days and a single 20 mg dose on the morning of day 8. Pharmacokinetic variables were determined from multiple venous blood samples collected on days 1 and 8 (haemodialysis day for subjects with severe renal impairment). Additional samples were collected from subjects with severe renal impairment on day 7 (nonhaemodialysis day).

RESULTS

On day 1 there were no statistically significant differences in the pharmacokinetics (AUC(0, 12 h), Cmax, tmax) of ziprasidone among subjects with normal renal function and those with mild, moderate and severe renal impairment. The AUC(0,12 h) and Cmax in subjects with mildly impaired renal function were statistically significantly greater than in those with moderately impaired renal function (P = 0.0163-0.0385). The mean AUC(0,12 h) was 272, 370, 250 and 297 ng ml(-1) h in groups 1, 2, 3 and 4, respectively. Corresponding mean Cmax values were 47, 61, 41 and 50 ng ml(-1) and corresponding mean tmax values were 5, 6, 5 and 5 h. On day 8 there were no statistically significant differences in the pharmacokinetics (AUC(0,12 h), Cmax, tmax, lambda(z), Fb) of ziprasidone among subjects with normal renal function and those with moderate or severe renal impairment. The AUC(0,12 h) in subjects with mild renal impairment was statistically significantly greater than those in the other three groups (P = 0.0025-0.0221), but this was not considered clinically significant. The mean AUC(0,12 h) were 446, 650, 389 and 427 ng ml(-1) h in groups 1, 2, 3 and 4, respectively. Corresponding mean Cmax values were 68, 93, 54 and 70 ng ml(-1), corresponding mean tmax values were 4, 5, 4 and 5 h and corresponding mean lambda(z) were 0.14, 0.11, 0.14 and 0.17 h(-1). The mean percentage Fb was 99.84-99.88% across all groups and the mean t(1/2),z ranged from 4.2 to 6.4 h. Comparison of the mean AUC(0,12 h) and Cmax values in subjects with severe renal impairment on day 7 with those on day 8 suggested that haemodialysis does not have a clinically significant effect on the pharmacokinetics of ziprasidone.

CONCLUSIONS

The findings of this study indicate that mild-to-moderate impairment of renal function does not result in clinically significant alteration of ziprasidone pharmacokinetics and therefore does not necessitate dose adjustment.

Impact of land drainage on peatland hydrology

There is a long history of drainage of blanket peat but few studies of the long-term hydrological impact of drainage. This paper aims to test differences in runoff production processes between intact and drained blanket peat catchments and determine whether there have been any long-term changes in stream flow since drainage occurred. Hillslope runoff processes and stream discharge were measured in four blanket peat catchments. Two catchments were drained with open-cut ditches in the 1950s. Ditching originally resulted in shorter lag times and flashier storm hydrographs but no change in the annual catchment runoff efficiency. In the period between 2002 and 2004, the hydrographs in the drained catchments, while still flashy, were less sensitive to rainfall than in the 1950s and the runoff efficiency had significantly increased. Drains resulted in a distinctive spatial pattern of runoff production across the slopes. Overland flow was significantly lower in the drained catchments where throughflow was more dominant. In the intact peatlands, matrix throughflow produced by peat layers below 10 cm was rare and produced <1% of the runoff. However, in drained peatlands, matrix throughflow in deeper peat layers was common and provided around 23% of the runoff from gauged plots. Macropore flow, the density of soil piping, and pipeflow were significantly greater in drained peatlands than in intact basins. Gradual changes to peat structure could explain the long-term changes in river flow, which are in addition to those occurring in the immediate aftermath of peatland drainage.

Neuropeptide Y receptor Y5 as an inducible pro-survival factor in neuroblastoma: implications for tumor chemoresistance

Neuroblastoma (NB) is a pediatric tumor of neural crest origin with heterogeneous phenotypes. While low stage tumors carry a favorable prognosis, over 50% of high risk NB relapses after treatment with a fatal outcome. Thus, developing therapies targeting refractory NB remains an unsolved clinical problem. Brain-derived neurotrophic factor (BDNF) and its TrkB receptor are known to protect NB cells from chemotherapy-induced cell death, while neuropeptide Y (NPY), acting via its Y2 receptor (Y2R), is an autocrine proliferative and angiogenic factor crucial for maintaining NB tumor growth. Here, we show that in NB cells, BDNF stimulates the synthesis of NPY and induces expression of another one of its receptors, Y5R. In human NB tissues, the expression of NPY and Y5R positively correlated with the expression of BDNF and TrkB. Functionally, BDNF triggered Y5R internalization in NB cells, while Y5R antagonist inhibited BDNF-induced p44/42-MAPK activation and its pro-survival activity. These observations suggested TrkB-Y5R transactivation that resulted in cross-talk between their signaling pathways. Additionally, NPY and Y5R were up-regulated in a BDNF-independent manner in NB cells under pro-apoptotic conditions, such as serum deprivation and chemotherapy, as well as in cell lines and tissues derived from post-treatment NB tumors. Blocking Y5R in chemoresistant NB cells rich in this receptor sensitized them to chemotherapy-induced apoptosis and inhibited their growth in vivo by augmenting cell death. In summary, the NPY/Y5R axis is an inducible survival pathway activated in NB by BDNF or cellular stress. Upon such activation, Y5R augments the pro-survival effect of BDNF via its interactions with TrkB receptor and exerts an additional BDNF-independent anti-apoptotic effect, both of which contribute to NB chemoresistance. Therefore, the NPY/Y5R pathway may become a novel therapeutic target for patients with refractory NB, thus far an incurable form of this disease.

Effect of selective or combined inhibition of integrins alpha(IIb)beta(3) and alpha(v)beta(3) on thrombosis and neointima after oversized porcine coronary angioplasty

BACKGROUND

Thrombosis and neointima formation limit the efficacy of coronary angioplasty (PTCA). Clinical trials have implicated the adhesion molecules integrin alpha(IIb)beta(3) and integrin alpha(v)beta(3) in these processes. The roles of these molecules in vascular smooth muscle cell adhesion, platelet aggregation, and the thrombotic and neointimal response to oversize porcine PTCA was investigated by use of a selective alpha(IIb)beta(3) antagonist (lamifiban), a selective alpha(v)beta(3) antagonist (VO514), and a combined alpha(IIb)beta(3)/alpha(v)beta(3) antagonist (G3580).

METHODS AND RESULTS

In vitro, both alpha(v)beta(3) inhibitors caused dose-dependent inhibition of porcine vascular smooth muscle cell adhesion to vitronectin but not to collagen type IV, fibronectin, or laminin, whereas selective alpha(IIb)beta(3) inhibition had no effect. Intravenous infusions of either alpha(IIb)beta(3) inhibitor in swine profoundly inhibited ex vivo platelet aggregation to ADP, whereas selective alpha(v)beta(3) inhibition had no effect. In a porcine PTCA model, intravenous infusions of the integrin antagonists were administered for 14 days after oversized balloon angioplasty injury. After PTCA, there was regional upregulation of integrin alpha(v)beta(3) in the developing neointima, as assessed by immunohistochemistry. Six hours after PTCA, obstruction of lumen by thrombus was reduced significantly by alpha(IIb)beta(3) inhibition compared with either control or alpha(v)beta(3) inhibition (mean control, 18.7%; VO514, 18.5%; lamifiban, 6.4%; G3580, 7.9%). Twenty-eight days after PTCA, there was a significant reduction of neointima with inhibitors of either integrin (mean intima/media ratio: control, 3.08; VO514, 1.33; lamifiban, 0.97; G3580, 1.32).

CONCLUSIONS

We conclude that both integrin alpha(IIb)beta(3) and integrin alpha(v)beta(3) participate in neointima development after experimental angioplasty.

Targeting of biotinylated compounds to its target tissue using a low-density lipoprotein receptor–avidin fusion protein

The very high binding affinity of avidin to biotin is one of the highest to occur in nature. We constructed a fusion protein composed of avidin and the endocytotic LDL receptor in order to target biotinylated molecules to cells of the desired tissues. In addition to the native avidin, charge-mutated and nonglycosylated avidins were utilized as part of the fusion proteins, in order to modify its properties. All of the fusion protein versions retained the biotin-binding capacity. Although the specificity was not increased, however, fusion proteins composed of natural avidin and nonglycosylated avidin bound most efficiently to the biotinylated ligands. Fluorescence microscopy and atomic force microscopy studies revealed the expression of the fusion protein on cell membranes, and demonstrated specific and high-affinity binding of biotin to the low-density lipoprotein receptor (LDLR)-avidin fusion protein in vitro. Additionally, systemically administered biotinylated ligand targeted with high specificity the intracerebral tumors of rats that were expressing fusion protein after the virus-mediated gene transfer. These results suggest that local gene transfer of the fusion protein to target tissues may offer a novel tool for the delivery of biotinylated molecules in vitro and in vivo for therapeutic and imaging purposes.