Mechanisms contributing to the deficits in hippocampal synaptic plasticity in mice lacking amyloid precursor protein

Abnormal processing of amyloid precursor protein (APP), in particular the generation of beta-amyloid (Abeta) peptides, has been implicated in the pathogenesis of Alzheimer's disease. This study examined the consequences of deleting the APP gene on hippocampal synaptic plasticity, and upon the biophysical properties of morphologically identified neurones in APP-null mice. The hippocampus of APP-null mice had a characteristic increase in gliosis throughout the CA1 region and a disruption of staining for the dendritic marker MAP2 and the presynaptic marker synaptophysin. The disruption of MAP2 staining was associated with a significant reduction in overall dendritic length and projection depth of biocytin labeled CA1 neurones. In two groups of APP-null mice that were examined at 8-12 months, and 20-24 months of age, there was an impairment in the formation of long-term potentiation (LTP) in the CA1 region compared to isogenic age matched controls. This LTP deficit was not associated with an alteration in the amplitude of EPSPs at low stimulus frequencies (0.033 Hz) or facilitation during a 100 Hz stimulus train, but was associated with a reduction in post-tetanic potentiation. Paired-pulse depression of GABA-mediated inhibitory post-synaptic currents was also attenuated in APP-null mice. These data demonstrate that the impaired synaptic plasticity in APP deficient mice is associated with abnormal neuronal morphology and synaptic function within the hippocampus.

Safety and biological efficacy of an adeno-associated virus vector-cystic fibrosis transmembrane regulator (AAV-CFTR) in the cystic fibrosis maxillary sinus

OBJECTIVE

The host immune response and low vector efficiency have been key impediments to effective cystic fibrosis transmembrane regulator (CFTR) gene transfer for cystic fibrosis (CF). An adeno-associated virus vector (AAV-CFTR) was used in a phase I dose-escalation study to transfer CFTR cDNA into respiratory epithelial cells of the maxillary sinus of 10 CF patients.

STUDY DESIGN

A prospective, randomized, unblinded, dose-escalation, within-subjects, phase I clinical trial of AAV-CFTR was conducted.

PATIENTS

Ten patients with previous bilateral maxillary antrostomies were treated.

MAIN OUTCOME MEASURES

Safety, gene transfer as measured by semiquantitative polymerase chain reaction (PCR), and sinus transepithelial potential difference (TEPD) were measured.

RESULTS

The highest level of gene transfer was observed in the range of 0.1-1 AAV-CFTR vector copy per cell in biopsy specimens obtained 2 weeks after treatment. When tested, persistence was observed in one patient for 41 days and in another for 10 weeks. Dose-dependent changes in TEPD responses to pharmacologic intervention were observed following treatments. Little or no inflammatory or immune responses were observed.

CONCLUSION

AAV-CFTR administration to the maxillary sinus results in successful, dose-dependent gene transfer to the maxillary sinus and alterations in sinus TEPD suggestive of a functional effect, with little or no cytopathic or host immune response. Further study is warranted for AAV vectors as they may prove useful for CFTR gene transfer and other in vivo gene transfer therapies. A prospective, randomized, double-blind, placebo-controlled, within-subjects, phase II clinical trial of the effect AAV-CFTR on clinical recurrence of sinusitis will determine the clinical efficacy of AAV gene therapy for CF.

Development and validation of the Burton Score: a tool for nutritional assessment

This paper describes the development and validation of the Burton Score, a nutritional assessment tool based on the Waterlow score, with the rationale that since nurses already collect data for one score, it would only lead to unnecessary duplication of effort if a totally different scoring scheme were to be used for nutritional assessment. Initial cut offs were determined by a pilot study of 26 patients on an elderly care ward and validated by comparing the nutritional status of 263 patients estimated by the Burton score with a dietitian's assessment of nutrition. The validation study showed that although there was significant correlation between the Burton and Waterlow scores the Burton score correlated more closely with the dietitian's assessments. The King's Fund report of 1992 stated that all patients should have assessment of nutritional status on admission to hospital: we believe the Burton score could provide a simple tool to achieve this goal.

Pharmacokinetics and pharmacodynamics of sibrafiban (Ro 48-3657), an orally active IIb/IIIa antagonist, administered alone or in combination with heparin, aspirin, and recombinant tissue-type plasminogen activator in beagles

This study characterized the pharmacokinetics (PK) and pharmacodynamics (PD) of sibrafiban (Ro 48-3657) in the presence of aspirin, heparin, and recombinant tissue-type plasminogen activator (rt-PA) in beagles. Sibrafiban is a double prodrug that undergoes bioconversion to the inactive prodrug Ro 48-3656 and to the active IIb/IIIa antagonist, Ro 44-3888, after oral administration. After oral sibrafiban, peak Ro 48-3656 plasma concentrations were observed earlier than Ro 44-3888 and were five- to sixfold higher than Ro 44-3888 peak concentrations. Administration of sibrafiban with heparin and aspirin or heparin and rt-PA did not alter sibrafiban PK. Ro 48-3656 and Ro 44-3888 PK and inhibition of platelet-aggregation profiles in groups treated with sibrafiban and heparin/aspirin or sibrafiban and heparin/rt-PA were similar to those of the group receiving sibrafiban alone. Sibrafiban resulted in >80% inhibition of adenosine diphosphate (ADP)-mediated platelet aggregation and an approximate sixfold increase in bleeding time (BT) compared with baseline measurements. The BT increase was greater in the sibrafiban, heparin, and rt-PA-treated group, during rt-PA administration, compared with the group treated with sibrafiban alone. The recovery of platelet aggregation may be slower after administration of sibrafiban with heparin and rt-PA. Sibrafiban had no effect on rt-PA PK or heparin PD.

Effect of troglitazone on fibrinolysis and activated coagulation in patients with non-insulin-dependent diabetes mellitus

The objective of this study was to determine if treatment of non-insulin-dependent diabetes mellitus (NIDDM) patients with the "insulin sensitizer" troglitazone, both as monotherapy and in combination with insulin, corrects the impaired fibrinolysis and activated coagulation associated with NIDDM. Patients participating in two clinical trials comparing troglitazone and placebo in patients with NIDDM were studied at the time of randomization and after 26 weeks of treatment. Eighteen patients were treated with troglitazone (ten in combination with insulin and eight as monotherapy) and eight were treated with placebo (four in each trial). Plasma concentrations of plasminogen activator inhibitor (PAI-1), prothrombin fragment F1+2, fibrinogen, and von Willebrand Factor (vWF) activity were measured. Plasma PAI-1 concentrations fell significantly from a mean of 68.8 +/- 32.3 ng/mL to 40.4 +/- 20.4 in the troglitazone treated group, but did not change significantly in the placebo treated group. Plasma PAI-1 concentrations were elevated in 15 patients treated with troglitazone and fell to normal in eight of them. There was no significant change in plasma F1+2, vWF, and fibrinogen, but plasma C-peptide and triglyceride concentrations fell significantly with troglitazone. This study demonstrates that troglitazone treatment is associated with a significant fall in plasma PAI-1 antigen concentrations in patients with NIDDM and, therefore, may have a beneficial effect on fibrinolysis.