Development and characterization of two novel 68 Ga-labelled neuropeptide Y short analogues with potential application in breast cancer imaging

In vivo receptor targeting with radiolabelled peptide-based probes is an attractive approach for the development of novel radiotracers for molecular imaging. This work presents the development and characterization of two novel neuropeptide Y analogues labelled with a positron emitter 68 Ga, for potential use in breast cancer imaging. Both analogues share the same amino acid sequence and were derivatized with NOTA through either a lysine linker (L1) or an acetylated lysine (L2). In both cases, a single product with radiochemical purity higher than 95% was obtained. The two complexes were hydrophilic, showed remarkable in vitro stability, good cellular uptake, binding affinity in the nanomolar range and high cellular internalization rate. Biodistribution studies revealed low blood uptake and elimination through the urinary tract. The addition of an acetyl group in the spacer increased the lipophilicity of C2 and modified the reactivity of the ε-amino group of the lysine which resulted in lower protein binding and lower percentage of injected dose in bladder and urine. The tumour versus muscle ratio was (3.8 ± 0.4) for 68 Ga-L1 and (4.7 ± 0.4) for 68 Ga-L2. These results encourage performing further studies in order to complete the evaluation of both tracers as potential radiopharmaceutical for breast cancer imaging.

Exercise and variations in neuropeptide concentrations in rheumatoid arthritis

The aim of the present study was to investigate the influence of an exercise program on neuropeptide concentrations, disease activity, impairments and disabilities in rheumatoid arthritis (RA). Eleven females (median age 60 years, median disease duration 6.5 years, ARA functional classes I or II) exercised 30 min daily for 4 weeks. The urine concentrations of calcitonin gene-related peptide-like immunoreactivity (CGRP-LI) and neuropeptide Y-like immunoreactivity (NPY-LI) were analyzed 1 week prior to exercise start, at exercise start, after 2 and 4 weeks of exercise, and after a 4-week follow-up period. Measurements of disease activity, aerobic capacity, grip force, limb muscle function, and activities of daily living (ADL) were also undertaken. The results indicate a decrease (md 5.64 pM to md 3.48 pM, P</=0.05) of CGRP-LI concentrations after 4 weeks' exercise. NPY-LI concentrations remained unchanged, as did disease activity and aerobic capacity. Muscle function and ADL capacity improved significantly (P</=0.05) after the exercise period. Only the improved grip force remained after the follow-up period. In conclusion the results indicate that decreased CGRP-LI concentration, probably reflecting a decreased sympathetic tone, follows physical exercise and suggest that regular physical activity might be important among individuals with RA to maintain a decreased sympathetic tone and less symptoms from their disease.

Elevated plasma immunoreactive neuropeptide Y concentrations and its increased urinary excretion in patients with advanced diabetic nephropathy

Neuropeptide Y (NPY) is a potent vasoconstrictor peptide that is abundant in the brain and the peripheral sympathetic nervous system. In the present study we investigated possible changes in plasma immunoreactive (IR)-NPY concentrations and urinary IR-NPY excretion in patients with non-insulin dependent diabetes mellitus (NIDDM) and the relationship to diabetic complications, such as nephropathy and neuropathy. IR-NPY in plasma and urine was measured by radioimmunoassay in 69 patients with NIDDM. Plasma IR-NPY concentrations in patients with advanced nephropathy (creatinine clearance <30 ml/min) (100.5 +/- 10.3 pmol/l, n=9, mean +/- SEM) were higher than in the control subjects (55.0 +/- 6.8 pmol/l, n=15) (P<0.02). Urinary excretion of IR-NPY and fractional excretion of NPY were also increased in the patients with advanced nephropathy. Sephadex G-50 column chromatography of the urine extracts obtained from healthy subjects, diabetic patients with renal failure and non-diabetic patients with renal failure showed an immunoreactive peak eluting in the NPY position. On the other hand, neither plasma nor urinary IR-NPY was high in patients with retinopathy, or in patients with peripheral neuropathy. The present study has, for the first time, shown high plasma IR-NPY concentrations and urinary IR-NPY excretion in NIDDM patients with advanced nephropathy.

Increased basal concentrations of plasma endothelin in borderline hypertension

BACKGROUND

There is evidence for an altered endothelial function in established hypertension but little is known about endothelial function in borderline hypertension. It has also been suggested that the early stages of hypertension are characterized by an increased sympathetic drive.

OBJECTIVE

To investigate whether alterations in endothelin, neuropeptide Y (NPY) and calcitonin gene-related peptide (CGRP) are already present in the borderline hypertensive stage.

DESIGN

A case-control study of age-matched men recruited from a population screening programme.

METHODS

Seventy-five men with stable borderline hypertension [diastolic blood pressure (DBP), 85-94 mmHg] and 75 age- and sex-matched normotensive controls (DBP < or = 80 mmHg) were investigated. Plasma samples were drawn in a standardized fashion, and extracted and analysed using competitive radio immunoassays.

RESULTS

Basal concentrations of NPY and CGRP were similar in the two groups (28.4 versus 26.7 pmol/l and 24.2 versus 21.7 pmol/l, respectively). Basal concentrations of endothelin were significantly higher in the borderline hypertensive group (2.0 versus 1.5 pmol/l, P < 0.0001).

CONCLUSIONS

These results suggest that a disturbed endothelial function, represented by endothelin, could be involved in the early hypertensive processes. They also suggest that these changes could be present before the basal sympathetic/parasympathetic drive alters, warranting further research into this area.

Plasma concentrations and urinary excretion of regulatory peptides in patients with urticaria pigmentosa

Patients with urticaria pigmentosa were investigated during symptom-free interval regarding plasma concentrations and urinary excretion of immunoreactive regulatory peptides: calcitonin gene-related peptide (CGRP), gastrin, neurokinin A (NKA), neuropeptide Y (NPY), somatostatin (SOM), substance P (SP) and vasoactive intestinal peptide (VIP). The plasma concentrations of these peptides, except for CGRP, were below the detection limit. The urinary excretion of the regulatory peptides were not higher in the patient group than in the controls, but in individual patients there was high urinary excretion of SP and VIP. A lower urinary excretion of CGRP was found in the patient group in addition to a tendency to a lower plasma concentration.