Distribution of Droplets and Immune Responses After Aerosol and Intra-Nasal Delivery of Influenza Virus to the Respiratory Tract of Pigs.

Recent evidence indicates that local immune responses and tissue resident memory T cells (TRM) are critical for protection against respiratory infections but there is little information on the contributions of upper and lower respiratory tract (URT and LRT) immunity. To provide a rational basis for designing methods for optimal delivery of vaccines to the respiratory tract in a large animal model, we investigated the distribution of droplets generated by a mucosal atomization device (MAD) and two vibrating mesh nebulizers (VMNs) and the immune responses induced by delivery of influenza virus by MAD in pigs. We showed that droplets containing the drug albuterol, a radiolabel (99mTc-DTPA), or a model influenza virus vaccine (S-FLU) have similar aerosol characteristics. 99mTc-DTPA scintigraphy showed that VMNs deliver droplets with uniform distribution throughout the lungs as well as the URT. Surprisingly MAD administration (1ml/nostril) also delivered a high proportion of the dose to the lungs, albeit concentrated in a small area. After MAD administration of influenza virus, antigen specific T cells were found at high frequency in nasal turbinates, trachea, broncho-alveolar lavage, lungs, tracheobronchial nodes, and blood. Anti-influenza antibodies were detected in serum, BAL and nasal swabs. We conclude that the pig is useful for investigating optimal targeting of vaccines to the respiratory tract.

Simultaneous Measurement of Gastric Emptying of a Soup Test Meal Using MRI and Gamma Scintigraphy.

Measurement of gastric emptying is of clinical value for a range of conditions. Gamma scintigraphy (GS) has an established role, but the use of magnetic resonance imaging (MRI) has recently increased. Previous comparison studies between MRI and GS showed good correlation, but were performed on separate study days. In this study, the modalities were alternated rapidly allowing direct comparison with no intra-individual variability confounds. Twelve healthy participants consumed 400 g of Technetium-99m (99mTc)-labelled soup test meal (204 kcal) and were imaged at intervals for 150 min, alternating between MRI and GS. The time to empty half of the stomach contents (T1/2) and retention rate (RR) were calculated and data correlated. The average T1/2 was similar for MRI (44 ± 6 min) and GS (35 ± 4 min) with a moderate but significant difference between the two modalities (p < 0.004). The individual T1/2 values were measured, and MRI and GS showed a good positive correlation (r = 0.95, p < 0.0001), as well as all the RRs at each time point up to 120 min. Gastric emptying was measured for the first time by MRI and GS on the same day. This may help with translating the use of this simple meal, known to elicit reliable, physiological, and pathological gastrointestinal motor, peptide, and appetite responses.

Glycaemic, gastrointestinal, hormonal and appetitive responses to pearl millet or oats porridge breakfasts: a randomised, crossover trial in healthy humans.

Whole-grain cereal breakfast consumption has been associated with beneficial effects on glucose and insulin metabolism as well as satiety. Pearl millet is a popular ancient grain variety that can be grown in hot, dry regions. However, little is known about its health effects. The present study investigated the effect of a pearl millet porridge (PMP) compared with a well-known Scottish oats porridge (SOP) on glycaemic, gastrointestinal, hormonal and appetitive responses. In a randomised, two-way crossover trial, twenty-six healthy participants consumed two isoenergetic/isovolumetric PMP or SOP breakfast meals, served with a drink of water. Blood samples for glucose, insulin, glucagon-like peptide 1, glucose-dependent insulinotropic polypeptide (GIP), peptide YY, gastric volumes and appetite ratings were collected 2 h postprandially, followed by an ad libitum meal and food intake records for the remainder of the day. The incremental AUC (iAUC2h) for blood glucose was not significantly different between the porridges (P > 0·05). The iAUC2h for gastric volume was larger for PMP compared with SOP (P = 0·045). The iAUC2h for GIP concentration was significantly lower for PMP compared with SOP (P = 0·001). Other hormones and appetite responses were similar between meals. In conclusion, the present study reports, for the first time, data on glycaemic and physiological responses to a pearl millet breakfast, showing that this ancient grain could represent a sustainable alternative with health-promoting characteristics comparable with oats. GIP is an incretin hormone linked to TAG absorption in adipose tissue; therefore, the lower GIP response for PMP may be an added health benefit.

Nasal Administration and Plasma Pharmacokinetics of Parathyroid Hormone Peptide PTH 1-34 for the Treatment of Osteoporosis.

Nasal delivery of large peptides such as parathyroid 1-34 (PTH 1-34) can benefit from a permeation enhancer to promote absorption across the nasal mucosa into the bloodstream. Previously, we have published an encouraging bioavailability (78%), relative to subcutaneous injection in a small animal preclinical model, for a liquid nasal spray formulation containing the permeation enhancer polyethylene glycol (15)-hydroxystearate (Solutol® HS15). We report here the plasma pharmacokinetics of PTH 1-34 in healthy human volunteers receiving the liquid nasal spray formulation containing Solutol® HS15. For comparison, data for a commercially manufactured teriparatide formulation delivered via subcutaneous injection pen are also presented. Tc-99m-DTPA gamma scintigraphy monitored the deposition of the nasal spray in the nasal cavity and clearance via the inferior meatus and nasopharynx. The 50% clearance time was 17.8 min (minimum 10.9, maximum 74.3 min). For PTH 1-34, mean plasma Cmax of 5 pg/mL and 253 pg/mL were obtained for the nasal spray and subcutaneous injection respectively; relative bioavailability of the nasal spray was ≤1%. Subsequently, we investigated the pharmacokinetics of the liquid nasal spray formulation as well as a dry powder nasal formulation also containing Solutol® HS15 in a crossover study in an established ovine model. In this preclinical model, the relative bioavailability of liquid and powder nasal formulations was 1.4% and 1.0% respectively. The absolute bioavailability of subcutaneously administered PTH 1-34 (mean 77%, range 55-108%) in sheep was in agreement with published human data for teriparatide (up to 95%). These findings have important implications in the search for alternative routes of administration of peptides for the treatment of osteoporosis, and in terms of improving translation from animal models to humans.

PEGylation and biodistribution of an anti-MUC1 aptamer in MCF-7 tumor-bearing mice.

Aptamers are characterized by a rapid renal clearance leading to a short in vivo circulating half-life. In order to use aptamers as anticancer therapeutic agents, their exposure time to the tumor has to be enhanced via increasing residency in the bloodstream. A way to achieve this goal is by conjugating the aptamer to poly(ethylene glycol) (PEG). Herein, we present the conjugation of a bifunctionalized anti-MUC1 aptamer (NH(2)-AptA-SR) with the (99m)Tc coordinating moiety MAG2 and either a conventional branched PEG or the comb-shaped PolyPEG via a two-step synthesis. The isolated products were radiolabeled with (99m)Tc and their biodistribution and tumor-targeting properties in MCF-7 tumor bearing mice were analyzed and compared.

Abnormalities of serotonin metabolism and their relation to symptoms in untreated celiac disease.

BACKGROUND AND AIMS: Serotonin (5-hydroxytryptamine [5-HT]) is a key modulator of gut function that in excess causes nausea, vomiting, and diarrhea. We recently showed that patients with post-infective irritable bowel syndrome have increased postprandial release of 5-HT associated with low-grade T-cell mediated inflammation. Celiac disease is another common disease in which a T-cell enteropathy is associated with increased mucosal 5-HT levels. Our aim was to determine how this inflammatory lesion influenced 5-HT bioavailability and how changes in 5-HT related to the symptoms of nausea, vomiting, and diarrhea seen in untreated celiac patients. METHODS: Fasting plasma and platelet 5-HT and postprandial plasma 5-HT levels were measured after a high-carbohydrate meal in celiac patients (n = 18) and healthy controls (n = 18) using high-pressure liquid chromatography. Dyspepsia was assessed during the postprandial period using a questionnaire. Finally, we compared the histology and mucosal 5-HT levels in duodenal biopsy specimens from celiac patients and controls. RESULTS: Celiac patients had increased 5-HT-containing enterochromaffin cell numbers and significantly higher peak plasma 5-HT levels (P = .0002), postprandial area under the curve (P = .0006), and platelet 5-HT stores (P = .031) than controls. Peak 5-HT levels correlated significantly with postprandial dyspepsia scores (P = .005). Celiac patients had higher duodenal 5-HT levels (P = .007) than controls. CONCLUSIONS: Celiac disease is associated with increased mucosal 5-HT content and enhanced 5-HT release from the upper small bowel, which correlates with postprandial dyspepsia. Serotonin excess may mediate dyspeptic symptoms in untreated celiac disease.

Abnormalities of 5-hydroxytryptamine metabolism in irritable bowel syndrome.

BACKGROUND & AIMS: 5-hydroxytryptamine-3 (5-HT 3 ) receptor antagonists improve symptoms in patients with diarrhea-predominant irritable bowel syndrome (D-IBS), 5-HT 4 agonists help those with constipation-predominant IBS (C-IBS). These data suggest excess or deficiency in 5-HT in D-IBS or C-IBS, respectively. Mucosal 5-HT-containing enterochromaffin cells (EC) are increased in postinfectious IBS (PI-IBS). Our aim was to define the postprandial release of 5-HT in PI-IBS and C-IBS patients and to relate this to mucosal 5-HT turnover. METHODS: Fifteen PI-IBS patients with diarrhea-predominant symptoms, 15 C-IBS patients, and 15 healthy controls underwent serial (platelet-poor) plasma 5-HT measurement for 3 hours after a standard 520-kcal meal. Rectal biopsy specimens were assayed for 5-HT and its metabolite 5-hydroxindoleacetic acid (5-HIAA). Colonic transit was measured using radio-opaque markers. RESULTS: Colonic transit was prolonged in C-IBS patients (mean +/- SEM) (49.4 +/- 3.8 h) compared with PI-IBS (26.7 +/- 4.5) and control patients (34.1 +/- 4.5) ( P < .02). Release of 5-HT assessed by area under the curve (AUC) of platelet-poor plasma 5-HT from 0 to 180 minutes postprandially was significantly lower in C-IBS patients (2593 +/- 309 mmol/L . min) compared with P-IBS (5623 +/- 721) and control patients (4822 +/- 598) ( P < .001). PI-IBS patients showed significantly higher peak postprandial plasma 5-HT values (median, range) (71.7, 43.4-125.3) ng/L compared with C-IBS patients (31.2, 15.2-40.5) and control patients (43.6, 26.7-50.1) ( P < .01). Mucosal 5-HT turnover as assessed by mucosal 5-HIAA/5-HT ratio was decreased in both C-IBS and PI-IBS patients, .14 (.01-.6) and .21 (.02-2.5), respectively, compared with control patients 1.12 (.17-3.1) ( P < .002). CONCLUSIONS: C-IBS patients show impaired postprandial 5-HT release whereas PI-IBS patients have higher peak levels, abnormalities that may be related to their different symptoms.

Abnormalities of GI transit in bloated irritable bowel syndrome: effect of bran on transit and symptoms.

OBJECTIVES: Bloating is an important but poorly understood symptom in irritable bowel syndrome (IBS) that is often aggravated by bran. The aim of our study was to determine whether IBS patients with bloating responded to bran differently from healthy controls. METHODS: A total of 12 patients with IBS (according to Rome I criteria), all with moderate to severe bloating, and 12 healthy controls participated in a two way, double blind, randomized, cross-over trial of bran versus placebo (crushed biscuits) 15 g b.i.d. An average daily pain index and bloating score were derived from daily symptom diaries. On day 14, gastric emptying, small bowel transit, percent remaining in ascending colon, and geometric center of a meal marker at 24 h were calculated from scintigraphic images obtained after ingesting a Tc99m-labeled rice pudding meal with 15 g of either placebo or coarse bran. RESULTS: Results are given as median (range). Bran significantly increased the pain index and bloating (p < 0.02) in IBS patients but not controls. The most striking finding was that the small bowel transit time of the meal without bran was markedly faster in IBS patients than in controls, being 203 min (range 109-313) versus 367 min (219-543), p < 0.001. Although in controls bran accelerated small bowel transit time to 262 min (180-380), p = 0.03, and significantly reduced % remaining in the ascending colon from 22% (0-46) to 3% (0-25), p = 0.03, this was not seen in the IBS patients. Bran accelerated whole gut transit as assessed by geometric center at 24 h in both IBS patients and controls. CONCLUSIONS: Bran accelerates small bowel transit and ascending colon clearance without causing symptoms in controls. Small bowel transit is rapid in IBS patients with bloating and, unlike in healthy control subjects, cannot be further accelerated by bran, which nevertheless aggravates symptoms of pain and bloating. We speculate that bran-induced bloating may originate in the colon rather than the small bowel.

Evaluation of Pulsincap to provide regional delivery of dofetilide to the human GI tract.

Pulsincap formulations designed to deliver a dose of drug following a 5-h delay were prepared to evaluate the capability of the formulation to deliver dofetilide to the lower gastrointestinal (GI) tract. By the expected 5-h release time, the preparations were well dispersed throughout the GI tract, from stomach to colon. Plasma analysis permitted drug absorption to be determined as a function of GI tract site of release. Dofetilide is a well-absorbed drug, but showed a reduction in observed bioavailability when delivered from the Pulsincap formulations, particularly at more distal GI tract sites. Dispersion of the drug from the soluble excipient used in this prototype formulation relies on a passive diffusion mechanism and the relevance of this factor to the reduced extent and consistency of absorption from the colon is discussed. In these studies the effects of the degree of dispersion versus the site of dispersion could not be ascertained; nevertheless the scintigraphic analysis demonstrated good in vitro-in vivo correlation for time of release from Pulsincap preparations. The combination of scintigraphic and pharmacokinetic analysis permits identification of the site of drug release from the dosage form and pharmacokinetic parameters to be studied in man in a non-invasive manner.