843 research outputs found
Attracting non-executive directors to the board
Companies that are performing poorly from a commercial
perspective and are struggling to tap into the advice and
guidance of well-qualified non-executive directors need to
consider new board members’ intrinsic motivations and the
potential for enhancing their reputation if they are to improve
the effectiveness of their board
To serve and protect: Enzyme inhibitors as radiopeptide escorts promote tumor targeting
Radiolabeled octreotide analogs are most successfully being applied today in clinical cancer imaging and treatment. Propagation of this paradigm to other radiopeptide families has been greatly hampered by the inherent poor metabolic stability of systemically administered peptide analogs. We hypothesized that the in vivo coadministration of specific enzyme inhibitors would improve peptide bioavailability and hence tumor uptake. Through single coinjection of the neutral endopeptidase inhibitor phosphoramidon (PA), we were able to provoke remarkable rises in the percentages of circulating intact somatostatin, gastrin, and bombesin radiopeptides in mouse models, resulting in a remarkable increase in uptake in tumor xenografts in mice. Methods: The peptide conjugates [DOTA-Ala1]SS14 (DOTA-Ala-Gly-c[Cys-Lys- Asn-Phe-Phe-Trp-Lys-Thr-Phe- Thr-Ser-Cys]-OH), PanSB1 (DOTAPEG2- DTyr-Gln-Trp-Ala-Val-βAla- His-Phe-Nle-NH2), and DOTA-MG11 (DOTA-DGlu-Al
Expression of Integrin α6β4 in Junctional Epidermolysis Bullosa
The integrin α6β4 is a member of the integrin family of adhesion receptors. The integrin α6β4 is preferentially expressed in stratified squamous epithelia, where it is localized in hemidesmosomes. A reduced number of rudimentary he- midesmosomes is often found in skin from patients with junctional epidermolysis bullosa (JEB). In this study we have investigated the expression of α6β4 in skin specimens of patients with junctional (one non-lethal, two lethal) and dystrophic (two) epidermolysis bullosa, using immunofluorescent (IF) staining with five different monoclonal antibodies against the α6 and β4 subunits. The intensity of IF staining of the integrin α6β4 and bullous pemphigoid antigen (BPA) was unreduced along the epidermal basement membrane zone (EBMZ) of all EB patients, compared to that in skin of healthy human controls. However, in the skin of two patients with lethal (Herlitz) JEB, who did not express GB3, IF staining of integrin α6β4 and BPA showed a “stitchy” discontinuous linear pattern along the EBMZ with interruptions at the borders of adjoining basal keratinocytes. The same results were obtained by immunoelectron microscopy. They corresponded with freeze-induced partial cell detachment from the basement membrane at the ultimate baso-lateral edge ot the basal keratinocytes in lethal JEB skin. The basal lamellipodia at that location almost completely lacked tonofilaments and hemidesmosomes. Furthermore, in JEB there was a split between the intra- and extracellular epitopes of the integrin α6β4 receptor, whereas the integrin remains intact in salt-split skin. This suggests that the defect is in α6β4 itself or perhaps its ligand
How does the general public balance convenience and cognitive pharmaceutical services in community pharmacy practice
Background: Community pharmacy is shifting its focus from traditional, product-focused roles to the provision of cognitive pharmaceutical services (CPS). Previous research has indicated that community pharmacists predominantly want to devote their capacity to CPS. Ideally, services provided also address users' needs. The general public's preferences regarding the services provided by community pharmacists are currently less understood. Aim: This study investigates the general public's preferences and perceived importance of CPS versus convenience in community pharmacy practice. Method: An online survey of 1.500 members of the Dutch Health Care Consumer Panel containing questions regarding preferences for CPS and convenience was distributed. Descriptive statistics and linear regression analysis were performed to investigate the relationship between preferences and participant characteristics. Results: 516 panel members completed all questions regarding preferences and importance of the availability of services. The majority preferred convenience (68.2%) and a smaller proportion preferred CPS (27.7%). However, participants considered it important from a societal viewpoint that CPS is provided (45.0%). Participants who preferred CPS over convenience were generally older (p < 0.001) and used more medicines (p < 0.001). Conclusion: Convenience of community pharmacy services is most preferred by the general public. However, CPS is perceived as important, especially for elderly who use more medicines. Elderly patients who use more medicines more often rate CPS as more important than convenience. These findings suggest that community pharmacists should ensure that pharmacy logistics are organized efficiently before focusing on the provision of CPS
Testicular cancer: Determinants of cisplatin sensitivity and novel therapeutic opportunities:Determinants of cisplatin sensitivity and novel therapeutic opportunities
Testicular cancer (TC) is the most common solid tumor among men aged between 15 and 40 years. TCs are highly aneuploid and the 12p isochromosome is the most frequent chromosomal abnormality. The mutation rate is of TC is low, with recurrent mutations in KIT and KRAS observed only at low frequency in seminomas. Overall cure rates are high, even in a metastatic setting, resulting from excellent cisplatin sensitivity of TCs. Factors contributing to the observed cisplatin sensitivity include defective DNA damage repair and a hypersensitive apoptotic response to DNA damage. Nonetheless, around 10–20% of TC patients with metastatic disease cannot be cured by cisplatin-based chemotherapy. Resistance mechanisms include downregulation of OCT4 and failure to induce PUMA and NOXA, elevated levels of MDM2, and hyperactivity of the PI3K/AKT/mTOR pathway. Several pre-clinical approaches have proven successful in overcoming cisplatin resistance, including specific targeting of PARP, MDM2 or AKT/mTOR combined with cisplatin. Finally, patient-derived xenograft models hold potential for mechanistic studies and pre-clinical validation of novel therapeutic strategies in TC. While clinical trials investigating targeted drugs have been disappointing, pre-clinical successes with chemotherapy and targeted drug combinations fuel the need for further investigation in clinical setting
Adaptive changes in transmembrane transport and metabolism of triiodothyronine in perfused livers of fed and fasted hypothyroid and hyperthyroid rats
The transport and subsequent metabolism of triiodothyronine (T3) were studied in isolated perfused livers of euthyroid, hypothyroid, and hyperthyroid rats, both fed and 48-hour-fasted. T3 kinetics (transport and metabolism) during perfusion were evaluated by a two-pool model, whereas the metabolism of T3 was also investigated by determination of T3 breakdown products by chromatography of medium and bile. For comparison of groups, metabolism was corrected for differences in transport. Transport parameters in fed hypothyroid livers were not significantly changed as compared with euthyroid livers, whereas metabolism was decreased. In fed hyperthyroid livers, fractional transfer rate constants for influx (k21) and efflux (k12) were decreased and metabolism, corrected for differences in intracellular mass transfer, was increased. Furthermore, for transport in hyperthyroid livers it was shown that only total mass transfer (TMT) into the metabolizing liver compartment (not into the nonmetabolizing liver compartment) was decreased. Transport and metabolic parameters in fasted hypothyroid livers were decreased as compared with euthyroid fed livers. In fasted hyperthyroid livers, transport and metabolism were not significantly different as compared with that in euthyroid fed livers, so transport was increased versus hyperthyroid fed livers. It appeared therefore that fasting normalized the effects of hyperthyroidism on both the transport and metabolic processes of T3 in the liver. The present study demonstrates normal transport and decreased metabolism in livers of hypothyroid fed rats and decreased transport and increased metabolism in livers of hyperthyroid fed rats. In livers of hypothyroid fasted rats transport and metabolism were decreased, whereas in livers of hyperthyroid fasted rats transport and metabolism were not significantly different from that in euthyroid fed livers. These changes might favor tissue euthyroidism despite the altered thyroid and nutritional state, and can therefore be seen as adaptation mechanisms to these altered states at the tissue level
Iodine-131 labelled octreotide: Not an option for somatostatin receptor therapy
Gamma-emitting radiopeptides are useful for scintigraphy of tumours on the basis of receptor binding. Likewise, β-emitting radiopeptides may be used in radionuclide therapy of such tumours. As iodine-131 suggested to be suitable for this purpose, experiments were performed using three somatostatin analogues, in which the effects of coupling of a therapeutic dose of 131I to such peptides were investigated. This study deals with the radioiodination of very small amounts of peptide on a therapeutic scale, the required purification procedures after radioiodination, and the influence of high beta fluxes from 131I. On a peptide during radioiodination and purification. Based on the regularly used therapeutic doses of 131I in cancer treatment and our previous experience with [111In-DTPA-D-Phe1]-octreotide, it was assumed that a minimal effective therapeutic dose of 3.7 GBq 131I has to be coupled to a maximum of ≃ 100 μg peptide, representing only a slight excess of peptide over 131I. This contrasts with non-peptide radiopharmaceuticals in which high compound to radionuclide ratios are usually used. Labelling at low peptide to radionuclide ratios (low labelling yields) results in the formation of di-iodinated compounds, whereas at high peptide to radionuclide ratios (high labelling yields) mono-iodinated products of low specific activity are formed. Thus, after radioiodination the desired mono-iodinated peptide has to be separated from unreacted iodide, and from di-iodinated and unreacted peptide, as both compounds compete for the receptors. Possible radiolysis of the peptide during labelling and separation steps were investigated by irradiating 30 μg unlabelled peptide with 370 MBq 131I in a small volume. The peptide composition of the incubation mixtures was investigated by high-performance liquid chromatography after irradiation for 30 min to 24 h. The results showed that the peptide was degraded with a half-life of less than 1 h. During the preparation of a real therapeutic dose (at much higher β-flux) the peptide will be degraded even faster during the various steps required. In conclusion, intact mono-iodinated 131I-labelled somatostatin analogues for peptide receptor therapy will be difficult to obtain
The putative proteinase maturation protein A of Streptococcus pneumoniae is a conserved surface protein with potential to elicit protective immune responses
Surface-exposed proteins often play an important role in the interaction
between pathogenic bacteria and their host. We isolated a pool of
hydrophobic, surface-associated proteins of Streptococcus pneumoniae. The
opsonophagocytic activity of hyperimmune serum raised against this protein
fraction was high and species specific. Moreover, the opsonophagocytic
activity was independent of the capsular type and chromosomal genotype of
the pneumococcus. Since the opsonophagocytic activity is presumed to
correlate with in vivo protection, these data indicate that the protein
fraction has the potential to elicit species-specific immune protection
with cross-protection against various pneumococcal strains. Individual
proteins in the extract were purified by two-dimensional gel
electrophoresis. Antibodies raised against three distinct proteins
contributed to the opsonophagocytic activity of the serum. The proteins
were identified by mass spectrometry and N-terminal amino acid sequencing.
Two proteins were the previously characterized pneumococcal surface
protein A and oligopeptide-binding lipoprotein AmiA. The third protein was
the recently identified putative proteinase maturation protein A (PpmA),
which showed homology to members of the family of peptidyl-prolyl
cis/trans isomerases. Immunoelectron microscopy demonstrated that PpmA was
associated with the pneumococcal surface. In addition, PpmA was shown to
elicit species-specific opsonophagocytic antibodies that were
cross-reactive with various pneumococcal strains. This antibody
cross-reactivity was in line with the limited sequence variation of ppmA.
The importance of PpmA in pneumococcal pathogenesis was demonstrated in a
mouse pneumonia model. Pneumococcal ppmA-deficient mutants showed reduced
virulence. The properties of PpmA reported here indicate its potential for
inclusion in multicomponent protein vaccines
Increased extracellular matrix synthesis by smooth-muscle cells obtained from in vivo restenotic lesions by directional coronary atherectomy.
Investigation of particle accumulation, chemosensitivity and thermosensitivity for effective solid tumor therapy using thermosensitive liposomes and hyperthermia
Doxorubicin (Dox) loaded thermosensitive liposomes (TSLs) have shown promising results for hyperthermia-induced local drug delivery to solid tumors. Typically, the tumor is heated to hyperthermic temperatures (41-42 °C), which induced intravascular drug release from TSLs within the tumor tissue leading to high local drug concentrations (1-step delivery protocol). Next to providing a trigger for drug release, hyperthermia (HT) has been shown to be cytotoxic to tumor tissue, to enhance chemosensitivity and to increase particle extravasation from the vasculature into the tumor interstitial space. The latter can be exploited for a 2-step delivery protocol, where HT is applied prior to i.v. TSL injection to enhance tumor uptake, and after 4 hours waiting time for a second time to induce drug release. In this study, we compare the 1- and 2-step delivery protocols and investigate which factors are of importance for a therapeutic response. In murine B16 melanoma and BFS-1 sarcoma cell lines, HT induced an enhanced Dox uptake in 2D and 3D models, resulting in enhanced chemosensitivity. In vivo, therapeutic efficacy studies were performed for both tumor models, showing a therapeutic response for only the 1-step delivery protocol. SPECT/CT imaging allowed quantification of the liposomal accumulation in both tumor models at physiological temperatures and after a HT treatment. A simple two compartment model was used to derive respective rates for liposomal uptake, washout and retention, showing that the B16 model has a twofold higher liposomal uptake compared to the BFS-1 tumor. HT increases uptake and retention of liposomes in both tumors models by the same factor of 1.66 maintaining the absolute differences between the two models. Histology showed that HT induced apoptosis, blood vessel integrity and interstitial structures are important factors for TSL accumulation in the investigated tumor types. However, modeling data indicated that the intraliposomal Dox fraction did not reach therapeutic relevant concentrations in the tumor tissue in a 2-step delivery protocol due to the leaking of the drug from its liposomal carrier providing an explanation for the observed lack of efficacy
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